US20070223061A1 - Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction - Google Patents
Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction Download PDFInfo
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- US20070223061A1 US20070223061A1 US11/689,115 US68911507A US2007223061A1 US 20070223061 A1 US20070223061 A1 US 20070223061A1 US 68911507 A US68911507 A US 68911507A US 2007223061 A1 US2007223061 A1 US 2007223061A1
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- Prior art keywords
- original
- image reading
- image
- reference member
- image sensor
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
- H04N1/203—Simultaneous scanning of two or more separate pictures, e.g. two sides of the same sheet
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
- H04N1/203—Simultaneous scanning of two or more separate pictures, e.g. two sides of the same sheet
- H04N1/2032—Simultaneous scanning of two or more separate pictures, e.g. two sides of the same sheet of two pictures corresponding to two sides of a single medium
- H04N1/2034—Simultaneous scanning of two or more separate pictures, e.g. two sides of the same sheet of two pictures corresponding to two sides of a single medium at identical corresponding positions, i.e. without time delay between the two image signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
- H04N2201/04—Scanning arrangements
- H04N2201/0402—Arrangements not specific to a particular one of the scanning methods covered by groups H04N1/04 - H04N1/207
- H04N2201/044—Moving a scanning element into cooperation with a calibration element, e.g. a grey-wedge mounted on the document support, or vice versa
Definitions
- the present invention relates to an image reading apparatus configured to read an image formed on an original, while conveying the original, an image reading unit thereof, and a reference member thereof for shading correction.
- an image reading apparatus configured to read an image formed on an original, while conveying the original, the original is illuminated with light from a light source, and reflected light from the original is focused by a rod lens array or the like, whereby the image on the original is read e.g. by a line image sensor.
- image data obtained from an output signal from the line image sensor when an original image is read is corrected using shading correction data formed based on an output signal from the line image sensor obtained when a white reference member is read.
- shading correction for optimizing the amount of light emitted from the light source to illuminate an original
- gain adjustment for optimizing an amplification factor for amplifying image signal output from the line image sensor
- the correction including the light amount adjustment and the gain adjustment performed so as to enable the line image sensor to uniformly read image information from the original will be referred to as “shading correction”.
- a member disposed in an original image reading position where the line image sensor reads an image on an original, for supporting a conveyed original from the reverse side of the same original has a color (black in general) other than white for the purpose of detection of a boundary between the original image and the background image, detection of a skew-feeding of the original, and prevention of lack of hiding of a reverse side image of the original.
- the image reading apparatus 1000 shown in FIG. 22 is configured to read image information on an original D by a line image sensor 110 through a contact glass 150 while conveying the original D.
- the image reading apparatus 1000 includes a pickup roller 2 for picking up originals D, a feed roller 3 for feeding the originals D picked up by the pickup roller 2 , a retard roller 4 for separating the picked-up originals D one from another, and a registration roller pair 5 and a convey roller pair 7 each formed by a pair of rollers disposed at respective opposed locations, for conveying the originals D.
- the image reading apparatus 1000 moves the line image sensor 110 in a direction indicated by an arrow S in FIG. 18 and causes the line image sensor 110 to read a reference member 170 .
- the reference member 170 is disposed at a location opposed to the line image sensor 110 having been moved in the direction indicated by the arrow S.
- image data obtained based on an output from the line image sensor 110 when the line image sensor 110 has read the reference member 170 is stored, as shading correction data for shading correction, in association with each pixel of the line image sensor 110 .
- the image reading apparatus 1000 returns the line image sensor 110 to its original position (original image reading position), and causes the line image sensor 110 to read the image on the original D, while conveying the original D.
- the image data obtained from the output of the line image sensor 110 is corrected by shading correction performed with reference to the correction data stored in advance. It should be noted that whether or not the line image sensor 110 has been moved to a reference member reading position for reading the reference member 170 can be determined based on an output from a position sensor 120 .
- the position sensor 120 is a means for detecting the position of the line image sensor 110 .
- Some image reading apparatuses are configured such that not a line image sensor but a reference member is moved between original reading position and escape position.
- a technique has been proposed in which the reference member is exposed into an original conveying path during a period of reference member reading, and is retracted to a position where the reference member does not contact with a conveyed original, during a period of original reading (see e.g. Japanese Laid-Open Patent Publication (Kokai) No. 2005-102017).
- the reference member is disposed on the far side of the original conveying path from the line image sensor, at a location which enables the line image sensor to read the reference member.
- a second countermeasure has conventionally been proposed in which the reference member is disposed at a location which does not face the original conveying path and where dust and dirt are difficult to attach, and the reference member is moved to a reading position of the line image sensor when acquisition of shading correction data is performed using the line image sensor (see e.g. Japanese Laid-Open Patent Publications (Kokai) No. H10-304195 and No. 2005-102017).
- a conventional image reading apparatus of another type has an image reading unit which causes the line image sensor 110 to slidably move in a direction parallel to the contact glass 150 thereby enable the reading position of the image sensor to move between the original reading position and the reference member reading position.
- This type of image reading apparatus reads image information from an original D by the line image sensor 110 through the contact glass 150 while conveying the original D in a direction indicated by an arrow ‘a’ in FIG. 23 .
- a light source incorporated in the line image sensor 110 illuminate the original D through the contact glass 150 .
- the image reading apparatus moves the line image sensor 110 in a direction indicated by an arrow b in FIG.
- the image reading apparatus generates shading correction data for use in shading correction, based on a signal output from the line image sensor 110 having read the reference surface, and stores the generated shading correction data on a pixel-by-pixel basis.
- the image reading apparatus returns the line image sensor 110 to its original position to read the image on the original D while conveying the original D in the direction of the arrow a.
- the image reading apparatus performs shading correction on image data generated based on an output signal from the line image sensor 110 , by referring to the shading correction data stored in advance.
- the reference member 170 used here is implemented e.g. by a white film formed by silk printing or the like.
- Japanese Laid-Open Patent Publication (Kokai) No. S62-098861 discloses a flat bed scanner which uses the aforementioned white film as the reference member.
- Japanese Laid-Open Patent Publication (Kokai) No. 2005-102017 is advantageous in that originals do not rub against the reference member during conveyance, and hence the reference member is difficult to be scratched or soiled.
- paper powder produced and wafted during an original conveying period can be deposited on the reference member, which necessitates periodic cleaning of the reference member.
- paper powder is very fine, it is difficult to remove the paper powder deposited on the reference member completely.
- a mechanism for causing the reference member to be exposed to the original conveying path is necessitated, which can cause an increase in the number of component parts and make the construction of the apparatus complicated.
- the reference member 170 can be scratched, or dust, such as paper powder and swarf from rollers, can be attached to the reference member 170 . Therefore, if shading correction is performed with reference to the reference member 170 deprived of whiteness by being scratched or soiled, lines or streaks appear on read original images.
- white films formed by coating are liable to differ in thickness between individual units thereof, and even an individual white film is apt to have variation in thickness depending on the location thereon.
- the use of such a white film as a white reference leads to a single image which is partially degraded due to partial degradation of the image reading performance or occurrence of an image reading apparatus degraded in image reading performance.
- the present invention provides an image reading apparatus which is capable of performing accurate shading correction with simple arrangement while preventing a reference member from being scratched and paper powder and the like dust from being deposited on the reference member, and an image reading unit thereof, as well as a shading correction reference member thereof.
- an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to move the image sensor so as to enable the image sensor to alternatively read the original conveyed on the image reading location and the reference member, wherein arrangement of the image sensor and the reference member is so designed as to make the reference surface of said reference member isolated from the conveying path.
- the image sensor and the reference member are arranged such that the reference surface of the reference member is isolated from the conveying path. More specifically, the reference member is provided on the original conveying path-side surface of the contact glass. Further, the reference surface of the reference member is held in close contact with the contact glass. As a consequence, it is possible to perform accurate shading correction with the simple arrangement while preventing the reference member from being scratched and paper powder and the like dust from being attached to the reference member.
- the reference surface of the reference member can be held in close contact with the contact glass.
- the reference member can be disposed on the glass holding member.
- the reference member can be disposed on the glass holding member.
- the reference surface of the reference member can be protected from being soiled by paper powder and the like dust. Therefore, it is possible to perform accurate shading correction and dispense with cleaning of the reference member.
- an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to relatively move the image sensor and the reference member so as to enable the image sensor to alternatively read the original conveyed to the image reading location and the reference member, wherein arrangement of the image sensor and the reference member is so designed as to make the reference surface isolated from the conveying path, and the reference member is disposed on an original conveying path-side surface of the contact glass.
- an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to relatively move the image sensor and the reference member so as to enable the image sensor to alternatively read the original conveyed on the image reading location and the reference member, wherein arrangement of the image sensor and the reference member is so designed as to make the reference surface isolated from the conveying path, and the reference member is fixed to an opposite surface of the contact glass from an original conveying path-side surface thereof.
- the reference member is fixed to the opposite surface of the contact glass from the original conveying path-side surface thereof.
- the reference surface of the reference member is protected from being soiled by paper powder and the like dust. Therefore, it is possible to perform accurate shading correction and dispense with cleaning of the reference member.
- an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to relatively move the image sensor and the reference member so as to enable the image sensor to alternatively read the original conveyed on the image reading location and the reference member, wherein the reference member comprises a white coating film formed on an original conveying path-side surface of the contact glass, and a protective member covering at least a portion of the white coating film, for protection of the white coating film.
- an image reading apparatus configured to read an image formed on an original, comprising an image reading unit including a frame that has an opening formed in an original conveying path side thereof, and rotatably supports a pivot shaft of an image sensor housed in the frame, a contact glass disposed on the opening of the frame, configured to guide the original to an image reading location thereon, and a reference member disposed within the frame.
- the image reading unit provided in the image reading apparatus includes a frame that has an opening formed in an original conveying path side thereof, and rotatably supports a pivot shaft of an image sensor housed in the frame, a contact glass disposed on the opening of the frame, for guiding the original to an image reading location thereon, and a reference member disposed within the frame. Therefore, it is possible to prevent paper powder and the like dust attached to the upper surface of the contact glass i.e. attached to originals being conveyed out of the frame from entering the frame and from attaching to the white reference member. Thus, accurate shading correction can be achieved without necessitating cleaning of the reference member.
- an image reading unit provided in the image reading apparatus according to the fifth aspect of the present invention.
- an image reading apparatus for reading an image formed on an original, while conveying the original, comprising a contact glass configured to have an original conveying surface on which an original reading position and a reference member reading position exist, and guide the original on the original conveying surface, an image sensor configured to be capable of moving a reading position thereof between the original reading position and the reference member reading position, and read the image formed on the original guided on the original conveying surface, through the contact glass, and a shading correction reference member as a white reference for the image sensor, wherein the shading correction reference member comprises a white coating film formed on an original conveying path-side surface of the contact glass, and a protective member covering at least a portion of the white coating film, for protection of the white coating film.
- the reference member is formed by affixing the protective member, such as a white tape, to the white coating film, so that even if the thickness of the white coating film formed by painting or printing method is not uniform, the protective member, such as a white tape, or the two-sided tape for affixing the protective member to the white coating film functions like a back light to reflect light having passed through the white coating film, which makes it possible to maintain uniform whiteness of the reference member, as viewed through the contact glass. This enhances accuracy in shading correction, and therefore it is possible to maintain stable image reading performance.
- the white coating film does not require high hardness and is allowed to have a non-uniform thickness, so that it is possible to form the white coating film by an inexpensive method.
- the protective member suffices if only it can reflect light having passed through the white coating film, and is not required to be formed high dimensional accuracy.
- a durable protective member formed e.g. of metal it is not necessary to carry out replacement of the protective member, which provides an image reading apparatus that is easy to manufacture and maintain.
- the protective member can be a substantially white adhesive tape.
- the protective member can be substantially white, and the shading correction reference member can have a transparent fixing member provided between the protective member and the white coating film, for fixing the protective member to a surface of the white coating film.
- the shading correction reference member can have a substantially white fixing member provided between the protective member and the white coating film, for fixing the protective member to a surface of the white coating film.
- the shading correction reference member has a two-sided adhesive tape for fixing the protective member, in a manner opposed to the white coating film, to at least one of a portion of the white coating film and a portion of the contact glass other than a portion close to the reference member reading location.
- the fixing member can be a two-sided adhesive tape.
- the fixing member can be an adhesive.
- the protective member can be a sheet form member.
- the protective member is a sheet metal member.
- a shading correction reference member disposed at a reference member reading location on a contact glass provided in an image reading apparatus, comprising a white coating film formed on an original conveying path-side surface of the contact glass, and a protective member covering at least a portion of the white coating film, for protection of the white coating film.
- FIG. 1 is a schematic side cross-sectional view showing the internal construction of an image reading apparatus according to a first embodiment of the present invention.
- FIG. 2 is a schematic block diagram showing the electrical configuration of the image reading apparatus in FIG. 1 .
- FIGS. 3A and 3B are cross-sectional views of an image reading unit appearing in FIG. 1 , in a state during an original reading period, in which:
- FIG. 3A shows the image reading unit as viewed vertically
- FIG. 3B shows the image reading unit as viewed horizontally.
- FIGS. 4A and 4B are cross-sectional views of the image reading unit in a state during a reference member reading period, in which:
- FIG. 4A shows the image reading unit as viewed vertically
- FIG. 4B shows the image reading unit as viewed horizontally.
- FIGS. 5A and 5B are views of a drive section appearing in FIG. 1 and component parts associated therewith as viewed from above, in which:
- FIG. 5A shows a state during the original reading period
- FIG. 5B shows a state during the reference member reading period.
- FIGS. 6A and 6B are views of the drive section and component parts associated therewith, as viewed in an original conveying direction, in which:
- FIG. 6A shows a state in which the apparatus is closed during the original reading period
- FIG. 6B shows a state in which the apparatus is open during the reference member reading period.
- FIG. 7 is a diagram showing an output waveform obtained when an image reading operation is performed by a line image sensor while a pulse motor is rotated at a constant speed.
- FIGS. 8A and 8B are partial vertical cross-sectional views showing another example of the image reading unit, in which:
- FIG. 8A shows a state during the original reading period
- FIG. 8B shows a state during the reference member reading period.
- FIGS. 9A and 9B are partial vertical cross-sectional views showing still another example of the image reading unit, in which:
- FIG. 9A shows a state during the original reading period
- FIG. 9B shows a state during the reference member reading period.
- FIGS. 10A to 10D are partial cross-sectional views showing an example of the layout of a reference member, in which:
- FIG. 10A shows a case where the reference member is disposed on an opposite surface of a contact glass from an original conveying surface thereof;
- FIG. 10B shows a case where the reference member is disposed on an original conveying surface of a glass holding member
- FIG. 10C shows a case where the reference member is disposed on an opposite surface of the glass holding member from the original conveying surface thereof.
- FIG. 10D shows a case where a junction part is omitted from the layout shown in FIG. 10B .
- FIG. 11 is a schematic view of an image reading apparatus according to a second embodiment of the present invention.
- FIG. 12 is a schematic view of a variation of the image reading apparatus in FIG. 11 .
- FIG. 13 is a schematic view of another variation of the image reading apparatus in FIG. 11 .
- FIG. 14 is a schematic view of a line image sensor provided in an image reading unit appearing in FIG. 11 .
- FIGS. 15A and 15B are cross-sectional views showing the image reading unit and its surrounding, in which:
- FIG. 15A shows a state during the original reading period
- FIG. 15B shows a state during a shading correction data acquisition period.
- FIG. 16 is a perspective view of the image reading unit.
- FIG. 17 is a flowchart of a shading correction process executed by a CPU.
- FIGS. 18A and 18B are cross-sectional views showing the image reading unit according to a variation and its surrounding, in which:
- FIG. 18A shows a state during the original reading period
- FIG. 18B shows a state during the shading correction data acquisition period.
- FIG. 19 is a schematic side view of an image reading apparatus according to a third embodiment of the present invention.
- FIG. 20 is a schematic side view of a reference member appearing in FIG. 19 .
- FIG. 21 is a schematic side view of a variation of the reference member in FIG. 20 .
- FIG. 22 is a side view showing the internal construction of a conventional image reading apparatus.
- FIG. 23 is a schematic side view of an image reading unit of the conventional image reading apparatus.
- FIG. 1 is a schematic side cross-sectional view showing the internal construction of an image reading apparatus according to a first embodiment of the present invention.
- the arrangement of the image reading apparatus shown in FIG. 1 is given only by way of example, but it is not limitative.
- the image reading apparatus 1 is comprised of a pickup roller 2 that picks up originals D, a feed roller 3 that feeds the originals D picked up by the pickup roller 2 into the apparatus 1 , a retard roller 4 that separates the picked-up originals D one by one, a pair of registration rollers 5 disposed at respective locations opposed to each other for conveying an original D, an image reading unit 61 that reads image information on the upper surface (surface on a front side) of each original D conveyed by the registration roller pair 5 , an image reading unit 62 that reads image information on the lower surface (surface on a reverse side) of each conveyed original D, and a pair of convey rollers 7 disposed at respective locations downstream of the image reading units 61 and 62 in a manner opposed to each other for conveying the original D.
- the image reading apparatus 1 has an upper frame 81 pivotally movable about a pivot shaft 81 a and a lower frame 82 supporting the pivot shaft 81 a , and coveys the original D through a space enclosed by the upper frame 81 and the lower frame 82 .
- the upper frame 81 can be turned (opened/closed) manually so as to allow an original D conveyed and jammed in the apparatus 1 to be removed from the apparatus 1 .
- the upper frame 81 accommodates the feed roller 3 , one of the registration rollers 5 , the image reading unit 61 , and one of the convey rollers 7
- the lower frame 82 accommodates the retard roller 4 , the other one of the registration rollers 5 , the image reading unit 62 , and the other one of the convey rollers 7
- Portions (not shown) supporting the pivot shaft 81 a are integrally formed with the lower frame 82 , and extend from the respective sides (toward and away from the viewer viewing FIG. 1 ) in a manner sandwiching the upper frame 81 .
- the image reading unit 62 is fixed to the lower frame 82 .
- the image reading unit 61 is movably supported on the upper frame 81 by a plurality of swing arms 9 .
- Each of the swing arms 9 has one end thereof supported on the upper frame 81 , and the other end thereof supported on the image reading unit 61 .
- the one end of each swing arm 9 has a snap-fit structure, which facilitates assembly.
- a driving unit 10 is comprised of a drive mechanism and a drive motor accommodated in the vicinity of the portions of the lower frame 82 supporting the pivot shaft 81 a , for driving the protruding portions 18 x and 18 y of the respective slide cams 18 that protrude from the side surfaces of the respective image reading units 61 and 62 in the same direction (toward the viewer as viewed in FIG. 1 ).
- the pushing member 19 presses the protruding portions 18 x and 18 y to drive these, whereby the image reading units 61 and 62 are each switched from a state during the original reading period to a state during the reference member reading period.
- the pushing member 19 as one of component parts forming the driving unit 10 is caused to press the protruding portions 18 x and 18 y to thereby cause the respective image reading units 61 and 62 to move to the position where the reference members, referred to hereinafter, are read by the line image sensors, respectively.
- the image reading apparatus 1 generates shading correction data, based on reading signals obtained by the reading, and stores the generated shading correction data on a pixel-by-pixel basis. Thereafter, pressing of the protruding portions 18 x and 18 y by the pushing member 19 is stopped, and then originals D are fed into the apparatus 1 by the pickup roller 2 and the feed roller 3 and are separated one by one by the retard roller 4 .
- each original D is repeatedly scanned by the image reading units 61 and 62 in a main scanning direction (i.e. in a direction substantially orthogonal to the original conveying direction), whereby images on the respective upper and lower surfaces of the original D are read.
- image data generated based on an output signal from the line image sensor of each of the image reading units 61 and 62 is subjected to shading correction with reference to the stored shading correction data.
- the original D is nipped and conveyed by the convey roller pair 7 and discharged out of the apparatus 1 .
- Generation and storage of the shading correction data may be performed once for all loaded originals D at the start of reading operation or may be repeatedly performed for every several originals D.
- FIG. 2 is a schematic block diagram showing the electrical configuration of the image reading apparatus 1 in FIG. 1 .
- reference numeral 11 designates the line image sensor (image sensor) provided in each of the image reading units 61 and 62 .
- Reference numeral 111 designates a light source incorporated in the line image sensor 11 .
- Reference numeral 100 designates an A/D converter section that performs analog processing, such as amplification and black level clamp, on the image signals received from the respective line image sensors 11 and then A/D converts the signals.
- Reference numeral 101 designates an image processing section that controls the line image sensors 11 , the light sources 111 , the A/D converter section 100 , and so forth, and performs various kinds of image processing (including shading correction) on image data obtained by A/D conversion of the image signals.
- Reference numeral 102 designates an image storage section (image memory) that stores image data.
- Reference numeral 103 designates an interface section that connects the image processing section 101 to an external host apparatus, a network, and so forth via a signal line 109 .
- Reference numeral 104 designates a control section (CPU) that controls the overall operation of the image reading apparatus 1 .
- Reference numeral 105 designates a storage section (working memory) used by the CPU 104 for operation.
- the image processing section 101 , the CPU 104 , and the working memory 105 are interconnected by a bus 108 .
- the CPU 104 is configured to be able to access the image memory 102 via the image processing section 101 . Therefore, the CPU 104 can perform processing using image data stored in the image memory 102 , according to a program written in the working memory 105 .
- Reference numeral 112 designates a conveying motor for conveying originals D.
- the conveying motor 112 operates under the control of a motor driver 107 responsive to an instruction from the CPU 104 .
- a pulse motor 21 is one of the component parts forming the driving unit 10 .
- the pulse motor 21 causes rotating motion of the pushing member 19 to thereby slide the slide cam 18 , whereby each of the line image sensors 11 is moved between an original image reading position for reading an image on an original D and a reference member reading position for reading the reference member.
- the pulse motor 21 operates under the control of a motor driver 106 responsive to an instruction from the CPU 104 .
- FIG. 1 Next, the arrangement of the image reading unit 62 appearing in FIG. 1 will be described with reference to FIGS. 3A and 3B and FIGS. 4A and 4B .
- FIG. 3A is a vertical partial cross-sectional view of the image reading unit 62 during the original reading period, while FIG. 3B is a horizontal partial cross-sectional view of the same.
- FIG. 4A is a vertical partial cross-sectional view of the image reading unit 62 during the reference member reading period, while FIG. 4B is a horizontal partial cross-sectional view of the same.
- the image reading unit 61 and the image reading unit 62 are identical in construction, and hence a description will be given of the image reading unit 62 alone.
- the image reading unit 62 is comprised of the line image sensor 11 that reads images, a frame 12 that accommodates the line image sensor 11 , a printed circuit board 13 that causes the line image sensor 11 to operate, a flat cable 14 that connects between the line image sensor 11 and the printed circuit board 13 , a contact glass 15 that guides an original D to an original image reading location 15 a , a glass holding member 16 that holds the contact glass 15 , the reference member 17 having a white reference surface, the slide cam 18 that moves the line image sensor 11 to a predetermined position, and a tension spring 22 that urges the slide cam 18 to return the line image sensor 11 from the predetermined position to its home position.
- the frame 12 is formed with a through hole 12 a through which the flat cable 14 extends.
- the through hole 12 a is formed to have an eaves shape so as to prevent the entry of dirt and dust.
- the reference member 17 is disposed on the original conveying surface of the contact glass 15 at a location different from the original image reading location 15 a .
- the white reference lower surface of the reference member 17 as a portion close to the location corresponding to the reference member reading position, is held in intimate contact with the contact glass 15 by bonding, adhesion using an adhesive tape, or any other suitable method.
- the reference member 17 may be formed on the contact glass 15 by coating (painting or printing). Therefore, the white reference surface is prevented from being damaged even when a conveyed original D rubs against the reference member 17 , or from losing whiteness due to attachment of paper powder or dirt thereto.
- the line image sensor 11 has protrusions 11 a and 11 b each protruding rearward as viewed in FIG. 3B .
- the protrusion 11 a is fitted in a cam groove 18 a formed in the slide cam 18 . Further, the protrusion 11 a is fitted through an elongated hole 12 b formed in the frame 12 , whereby the movement of the line image sensor 11 in the main scanning direction is restricted.
- the protrusion 11 b is fitted in a cam groove 18 b also formed in the slide cam 18 .
- the slide cam 18 is formed with the cam grooves 18 a and 18 b in which the protrusions 11 a and 11 b are fitted, respectively, elongated holes 18 c and 18 d in which protrusions 12 c and 12 d protruding from the frame 12 are fitted, respectively, and a hook part 18 e to which the tension spring 22 is hooked.
- the slide cam 18 is under tension by the tension spring 22 held on a holding part 12 e of the frame 12 by the tension spring 22 under tension acting in a direction indicated by an arrow f in FIGS. 3B and 4B .
- the protruding portion 18 y as one end of the slide cam 18 (the protruding portion 18 x in the case of the image reading unit 61 ) is held in a state protruding from the frame 12 .
- the reference member reading period as shown in FIG.
- the protruding portion 18 y as one end of the slide cam 18 (the protruding portion 18 x in the case of the image reading unit 61 ) is held in a state retracted in the frame 12 of the image reading units 62 .
- the slide cam 18 is thus slidably engaged with the line image sensor 11 , and is driven in the main scanning direction i.e. the longitudinal direction of the line image sensor 11 , whereby the line image sensor 11 can be moved according to the shapes of the cam grooves 18 a and 18 b in the sub scanning direction to one of the original image reading position and the reference member reading position.
- FIG. 1 the arrangement of the driving unit 10 appearing in FIG. 1 will be described with reference to FIGS. 5A and 5B and FIGS. 6A and 6B .
- FIGS. 5A and 5B are views of the driving unit 10 and component parts associated therewith, as viewed from above, in which FIG. 5A shows a state during the original reading period, and FIG. 5B shows a state during the reference member reading period.
- the protruding portion 18 x is an end portion of the slide cam 18 protruding from a side surface of the image reading unit 62
- the protruding portion 18 y is an end portion of the slide cam 18 protruding from a side surface of the image reading unit 61 .
- the driving unit 10 is comprised of the pushing member 19 for pushing in the protruding portions 18 x and 18 y , an eccentric cam 20 for transmitting a driving force to the pushing member 19 , and the pulse motor 21 for rotating the eccentric cam 20 about a pivot shaft 20 b to actuate the pushing member 19 .
- the pushing member 19 has a contact surface 19 a held in contact with an eccentric cylindrical surface 20 a of the eccentric cam 20 , and the contact surface 19 b for being brought into contact with the protruding portions 18 x and 18 y .
- the pushing member 19 is configured such that the contact surface 19 a held in contact with the eccentric cylindrical surface 20 a is pushed by the rotation of the eccentric cam 20 about the axis of the pivot shaft 20 b and is rotated about the axis of the pivot shaft 19 d .
- the image reading unit 61 and the image reading unit 62 are arranged such that the protruding portion 18 x of the image reading unit 61 is positioned farther from the pivot 19 d than the protruding portion 18 y of image reading unit 62 so as to make a difference between the distance from the pivot 19 d to the protruding portion 18 x and that from the pivot 19 d to the protruding portion 18 y . Since the image reading units 61 and 62 are thus positioned, during the original reading period, the pushing member 19 is brought into contact with the protruding portion 18 y as shown in FIG. 5A , but on the other hand, the contact surface 19 b is kept from contact with the protruding portion 18 x . As a consequence, the image reading unit 61 movably supported by the swing arms 9 is allowed to vertically move smoothly in accordance with the varying thickness of originals.
- FIGS. 6A and 6B are views of the driving unit 10 and component parts associated therewith, as viewed in the original conveying direction, in which FIG. 6A shows a state in which the apparatus 1 is in closed state during the reference member reading period, and FIG. 6B shows a state in which the apparatus 1 is opened during the reference member reading period.
- the state where the apparatus 1 is closed is defined as a state in which the upper frame 81 and the lower frame 82 are held in meeting contact with each other as shown in FIG. 1 and the original conveying passage can normally function.
- the state where the apparatus 1 is open is defined as a state in which the upper frame 81 is in a lifted position by being turned upward around the pivot shaft 81 a , whereby the conveying passage is kept open for cleaning.
- the pushing member 19 has a sloping surface part 19 c formed on a contact portion thereof facing toward the image reading units 61 and 62 , and for contact with the protruding portion 18 x .
- the protruding portion 18 x pressed in by the pushing member 19 protrudes from the image reading unit 61 in a state freed from the pressing force of the pushing member 19 .
- the apparatus 1 is closed in this state, there is a fear that the protruding portion 18 x and the pushing member 19 collides with each other, causing breakage, unless the sloping surface part 19 c is not formed on the pushing member 19 .
- the pushing member 19 is formed with the sloping surface part 19 c , the protruding portion 18 x protruding from the image reading unit 61 is pressed in by being brought into abutment with the sloping surface part 19 c during the process of closing the apparatus 1 , which makes it possible to prevent breakage due to collision between the protruding portion 18 x and the pushing member 19 .
- the end of the protruding portion 18 x for contact with the sloping surface part 19 c to have a round shape (angle R), it is possible to further enhance the effect of preventing breakage due to collision between the protruding portion 18 x and the pushing member 19 .
- the image reading apparatus 1 can drive the slide cams 18 of the respective two image reading units 61 and 62 by the single driving unit 10 .
- a space required for arranging the motor and the driving force-transmitting mechanism can be reduced to thereby achieve reduction of the size of the apparatus 1 .
- the slide cams 18 can be externally driven from outside the respective image reading units 61 and 62 to thereby shift the position of the associated line image sensor 11 , so that in a case where the image reading apparatus is a single-sided reading apparatus, it is possible to form the apparatus 1 by the upper frame 81 accommodating an image reading unit and the lower frame 82 without an image reading unit, and provide the driving unit 10 in the lower frame 82 .
- the degree of freedom in configuration of the apparatus 1 can be enhanced.
- FIG. 7 is a diagram showing an output waveform obtained when an image reading operation is performed by the line image sensor 11 while the pulse motor 21 is rotated at a constant speed. Specifically, the diagram shows changes in the output value common to light-receiving elements of the line image sensor 11 with respect to the number of steps of the pulse motor 21 (driving amount of the driving unit 10 ) counted when an image reading operation is performed by the line image sensor 11 while rotating the pulse motor 21 at a constant speed.
- the line image sensor 11 moves from the position not opposed to the reference member 17 as shown in FIG. 3A to a position opposed to the reference member 17 as shown in FIG. 4A , and then returns to the position not opposed to the reference member 17 as shown in FIG. 3A .
- a reading operation is performed by the line image sensor 11 , and the line image sensor output value as shown in FIG. 7 is stored in the image memory 102 .
- the line image sensor output value is obtained by converting the line image sensor output as an analog signal into digital data by the A/D converter section 100 and then subjecting the digital data to offset correction.
- the CPU 104 performs processing for detecting a boundary between image data obtained by reading the reference member 17 in the position opposed to the reference member 17 and image data read in the position not opposed to the reference member 17 , from the image data stored in the image memory 102 .
- the CPU 104 stores information on which pulse of the pulse motor 21 corresponds to the detected boundary, and calculates a desirable stop position, whereby it is possible to know the number of steps of the pulse motor 21 required for moving the line image sensor 11 from the current operation starting position to the original image reading position or the reference member reading position. This step count is equal to the driving amount of the driving unit 10 .
- a midpoint ( 1 ) between a boundary (A) detected when the line image sensor 11 has moved from a position not opposed to the reference member 17 as shown in FIG. 3A to a position opposed to the reference member 17 as shown in FIG. 4A and a boundary (B) detected when the line image sensor 11 has moved from the position opposed to the reference member 17 to a position which ceases to be opposed to the reference member 17 as shown in FIG. 3A can be regarded as an optimum position for causing the line image sensor 11 to be opposed to the reference member 17 .
- a midpoint ( 2 ) between the boundary (B) detected when the line image sensor 11 has moved from the position opposed to the reference member 17 as shown in FIG. 4A to the position not opposed to the reference member 17 as shown in FIG. 3A and a boundary (C) detected when the line image sensor 11 has moved from the position not opposed to the reference member 17 to the position opposed to the reference member 17 as shown in FIG. 4A can be regarded as an optimum position for causing the line image sensor 11 to be not opposed to the reference member 17 .
- the reading operation is performed while rotating the pulse motor 21 at a constant speed, and driving amounts L 1 and L 2 of the pulse motor 21 required for moving the line image sensor 11 between the boundaries are each determined as respective step counts based on the changes in the output value shown in FIG. 7 .
- driving amounts L+L 1 ′ and L+L 1 +L 2 ′ of the pulse motor 21 required for moving the line image sensor 11 from the current operation starting position of the pulse motor 21 to the positions corresponding to the respective midpoints ( 1 ) and ( 2 ) can be each determined as respective step counts.
- the driving amount for moving the line image sensor 11 to the midpoint ( 1 ) as a driving amount for positioning the line image sensor 11 for the reference member reading operation and the driving amount for moving the line image sensor 11 to the midpoint ( 2 ) as a driving amount for positioning the line image sensor 11 for the original image reading operation, respectively.
- a light amount set value of the light source, a gain set value of the A/D converter section 100 , and the shading correction data are each set to a preset initial value (particularly suitably, immediately after assembling the apparatus 1 in a factory, for example).
- a method of utilizing the difference in magnitude between an output from the line image sensor 11 and a predetermined threshold value can be exemplified as an easy method to employ.
- the influence of variation in the amount of light from the light source or the like can make it impossible to discriminate between the scan image from the reference member 17 and that from the portion other than the reference member 17 using the preset initial values or the predetermined threshold value.
- the gain set value may be changed by adjusting an amplifier that amplifies an analog signal before A/D conversion, or by computing digital data after A/D conversion.
- the image reading apparatus 1 rotates the pulse motor 21 to bring the pushing member 19 and the slide cam 18 into the state shown in FIG. 5B , thereby moving the line image sensor 11 to the position opposed to the reference member 17 (see FIG. 4A ). Then, when the line image sensor 11 and the reference member 17 are opposed to each other such that the reading effective range of the line image sensor 11 is covered by the reference member 17 , the line image sensor 11 reads the reference member 17 . As a consequence, correction data generated based on the output from the line image sensor 11 is stored on a pixel-by-pixel basis, as shading correction data for use in shading correction. Thereafter, the image reading apparatus 1 rotates the pulse motor 21 to bring the pushing member 19 and the slide cam 18 into the state shown in FIG. 5A , thereby moving the line image sensor 11 to the position not opposed to the reference member 17 (see FIG. 3A ).
- the line image sensor 11 and the reference member 17 are arranged such that the reference surface of the reference member 17 is isolated from the conveying path for originals D. More specifically, the reference member 17 is disposed on the original conveying surface of the contact glass 15 , with the reference surface thereof held in intimate contact with the contact glass 15 . This prevents the reference surface from being scratched, and prevents deposition of paper powder or the like, which obviates the necessity of cleaning the reference member 17 . This makes it possible to acquire shading correction data without suffering from degradation of the whiteness of the reference surface, and perform shading correction with accuracy.
- the line image sensor 11 and the glass holding member 16 may be relatively moved to thereby shift the line image sensor 11 between the position opposed to the reference member 17 and the position not opposed to the reference member 17 .
- the image reading unit may be configured such that only the glass holding member 16 is moved during a transition period between the original reading period shown in FIG. 8A and the reference member reading period shown in FIG. 8B , or alternatively such that the line image sensor 11 and the glass holding member 16 are both moved during the transition period between the original reading period shown in FIG. 9A and the reference member reading period shown in FIG. 9B .
- the reference member 17 is provided on the original conveying surface of the contact glass 15 , this is not limitative. More specifically, the reference member 17 can be disposed at any location on the contact glass 15 or on the glass holding member 16 insofar as it is off the original image reading location 15 a .
- the reference member 17 may be disposed on the opposite side of the contact glass 15 from the original conveying surface thereof.
- the reference member 17 may be disposed on the original conveying surface of the glass holding member 16 as shown in FIG. 10B , or on the opposite side of the glass holding member 16 from the original conveying surface of the same as shown in FIG. 10C . In the case shown in FIG.
- the line image sensor 11 has to move over a junction part 16 a connecting between the contact glass 15 and the reference member 17 , which increases the distance of travel of the line image sensor 11 . Therefore, the junction part 16 a may be omitted as shown in FIG. 10D .
- the reference member 17 disposed as shown in FIGS. 10B and 10D requires sufficient strength and thickness for preventing the white reference surface thereof from being damaged by conveyed originals D.
- the white reference surface of the reference member 17 and the upper surface of the contact glass 15 as the surface for reading originals D are different in location from each other, and hence it is desirable to select a thickness of the contact glass 15 and a shape of the glass holding member 16 such that the surfaces of the two are both brought into focus.
- one of unevenesses which must be corrected by shading correction is variation in the amount of light from a rod lens array (not shown), but the profile of the variation in the light amount (i.e. light amount distribution profile) becomes different in a position away from a position in focus, which makes the shading correction inaccurate.
- the reference member reading operation can be performed in a position out of focus.
- the sloping surface part 19 c is formed on the pushing member 19 so as to prevent the protruding portion 18 x of the slide cam 18 from being broken when the apparatus 1 is opened during the reference member reading period
- the image reading apparatus 1 may be configured such that when the apparatus 1 is opened/closed during the reference member reading period, the opening/closing of the apparatus 1 is detected, and the pulse motor 21 is caused to rotate to bring the pushing member 19 into the state shown in FIG. 5A , thereby preventing breakage of the protruding portion 18 x.
- Detect means for detecting the opening/closing of the apparatus 1 may be implemented by any type of detector, including a microswitch, a photo-detector switch, and a magnetic detector switch. Alternatively, determination as to the opening/closing of the apparatus 1 may be performed by detecting that the read output from the line image sensor 11 has assumed a value quite different from one in the normal state. It is also possible to use a control means implemented e.g. by the CPU or a combination of the control means and a special-purpose electric circuit as a detect means for detecting the opening/closing of the apparatus 1 .
- the image reading apparatus is capable of double-sided reading of an original D
- the present invention can be applied to an image reading apparatus for single-sided reading.
- FIG. 11 is a schematic view of an image reading apparatus according to a second embodiment of the present invention.
- the arrangement of the image reading apparatus in FIG. 11 is illustrated by way of example, and hence this is not limitative.
- the image reading apparatus 1 ′ is comprised of a pickup roller 2 ′ that picks up originals D, a feed roller 3 ′ that feeds the originals D picked up by the pickup roller 2 ′ into the apparatus 1 ′, a retard roller 4 ′ that pairs with the feed roller 3 ′ to separate the picked-up originals D one by one, a registration roller pair 5 ′ for conveying the originals D while correcting skew of ones conveyed thereto in a skewed state, a pair of image reading units 61 ′ and 62 ′ that read images on the respective upper and lower surfaces of each of the originals D, convey roller pairs 7 ′ that further convey the originals D, and a discharge roller pair 8 ′ that discharges the originals D out of the apparatus.
- the image reading units 61 ′ and 62 ′ may be disposed at respective different locations in the original conveying direction instead of being disposed at the same location as shown in FIG. 11 .
- the image reading apparatus 1 ′ is divided into an upper frame 81 ′ and a lower frame 82 ′ by a conveying path along which originals D are conveyed.
- This construction makes it possible to open the conveying path by rotating the upper frame 81 ′ around a pivot shaft 81 a ′ manually when jamming of a original D has occurred in the image reading apparatus 1 ′ during conveyance thereof, and take out the jammed original from the conveying path.
- each of the two image reading units 61 ′ and 62 ′ reads images on respective originals conveyed, one by one, by the associated line image sensor in an original reading position.
- the present invention is not limited to the present embodiment insofar as the apparatus is provided with at least one image reading means requiring shading correction.
- the height of an original discharging position with respect to an original stack position is not particularly limited.
- the original discharging position may be provided below the original stack position as shown in FIG. 12 , or alternatively on the opposite side of the image reading apparatus 1 ′ from the original stack position as shown in FIG. 13 .
- each original is passed between the image reading units 61 ′ and 62 ′ by horizontally moving the original therethrough
- the image reading apparatus 1 ′ may be configured such that original D is passed between the image reading units 61 ′ and 62 ′ by vertically moving the original D therethrough.
- FIG. 14 is a schematic view of a line image sensor 44 provided in the image reading unit 62 ′ appearing in FIG. 11 .
- the image reading unit 61 ′ is identical in construction to the image reading unit 62 ′ except that the image reading unit 61 ′ reads not an image on the lower surface of the original D but an image on the upper surface of the same, and hence description thereof is omitted.
- the line image sensor 44 incorporates an LED 442 as a light source, a lens array 443 , and a light receiving element 441 .
- the line image sensor 44 causes reflected light from the original illuminated by the LED 442 to form an image on the light receiving element 441 by the lens array 443 and converts the image into an electric signal to thereby generate an image reading signal.
- FIGS. 15A and 15B are cross-sectional views showing the image reading unit 62 ′ and its surrounding in this embodiment, in which FIG. 15A shows a state during the original reading period, and FIG. 15B shows a state during a shading correction data acquisition period.
- the image reading unit 62 ′ has a frame 42 that has an opening formed on a side thereof along which an original D is conveyed, i.e. an upper side thereof, and pivotally supports a pivot shaft 45 of the line image sensor 44 accommodated therein.
- the image reading unit 62 ′ is further comprised of a contact glass 41 fitted in the opening of the frame 42 , for guiding the original D to the original reading location, and a white reference member 43 for shading correction (hereinafter simply referred to as “the white reference member 43 ) disposed within the frame 42 .
- This arrangement makes it possible to prevent paper powder and the like dust deposited on an original D conveyed to the upper surface of the contact glass 41 , i.e.
- the arrangement makes it possible to carry out a shading correction process, described in detail hereinafter, accurately without necessitating cleaning of the white reference member 43 .
- the white reference member 43 is disposed such that when the line image sensor 44 is rotated through 900 , the reference surface of the white reference member 43 faces a reading position of the line image sensor 44 .
- the line image sensor 44 is disposed such that the distance from the line image sensor 44 to the white reference member 43 during the shading correction data acquisition period (see FIG. 15B ) becomes equal to an optical distance from the line image sensor 44 to the surface of an original D (i.e. a distance corrected in view of the glass thickness of the contact glass 15 disposed between the line image sensor 44 and the surface of the original D) in the original image reading period (see FIG. 15A ).
- This is to equalize the reading conditions of the line image sensor 44 , i.e. the focal position and the amount of illuminating light, between during the original image reading period and during the shading correction data period.
- the difference in the amount of reflected light due to the difference in the optical distance may be corrected, instead of disposing the line image sensor 44 such that the optical distance is equalized as described above. Reading of the reference member 43 can be performed even in a position out of focus, and therefore it is assumed that the reading position includes positions deviated from the position in focus.
- FIG. 16 is a perspective view of the image reading unit 62 ′.
- the image reading unit 62 ′ has a sensor rotating mechanism comprised of the pivot shaft 45 and a motor 46 , and is capable of rotating the reading position of the line image sensor 44 through a desired angle.
- the sensor rotating mechanism may include a transmission mechanism comprised of gears or the like.
- the motor 46 may be replaced by a solenoid, a rotary solenoid, or the like actuator.
- FIG. 17 is a flowchart showing the shading correction process executed by the CPU.
- a control means detects that a power switch, not shown, of the image reading apparatus 1 ′ has been pressed by the user, it turns on the power supply to the electrical sections and components of the apparatus.
- a motor control section drives the motor 46 to rotate the line image sensor 44 into a state for acquisition of shading correction data (step S 702 ).
- the motor 46 starts rotation to rotate the line image sensor 44 until the reading position of the line image sensor 44 reaches the position for shading correction data acquisition (step S 703 ).
- a sensor control section delivers to the line image sensor 44 a control signal for causing the line image sensor 44 to read the white reference member 43 (step S 704 ).
- the line image sensor 44 starts reading the white reference member 43 , and generates a reading signal through the reading operation (step S 705 ).
- the sensor control section converts the reading signal into digital data at an A/D converter section, not shown, to thereby acquire the digital data as shading correction data for each pixel corresponding to each elements of the light receiving element 441 (step S 706 ).
- the shading correction data may be obtained by performing some computation on the digital data generated through the A/D conversion.
- the motor control section drives the motor 46 to rotate the line image sensor 44 into a state for reading of an original (step S 707 ).
- the motor 46 resumes the rotation to rotate the line image sensor 44 until the reading position of the line image sensor 44 returns to the position for original reading (step S 708 ).
- the sensor control section delivers to the line image sensor 44 a control signal for causing the line image sensor 44 to sequentially read conveyed originals (step S 710 ).
- the line image sensor 44 starts reading the originals, and sequentially generates reading signals by reading images on the respective originals D (step S 711 ).
- the sensor control section converts the reading signals into digital data at the A/D converter section, not shown, to thereby acquire the digital data as original image data (step S 712 ).
- shading correction is performed on the original image data based on the acquired shading correction data (step S 713 ), followed by terminating the present process. It should be noted that the shading correction data acquisition process may be started before reading of all the originals to be scanned is completed.
- the line image sensor 44 is rotated until the reading position thereof reaches the position for shading correction data acquisition (step S 703 ), and acquires shading correction data by reading the white reference member 43 (step S 706 ). Thereafter, the line image sensor 44 is rotated until the reading position thereof returns to the position for original reading (step S 711 ), and reads originals D (step S 711 ). This makes it possible to achieve accurate shading correction.
- the sensor rotating mechanism may have a pivot shaft 45 ′ having a pivotal axis thereof positioned apart from the longitudinal axis of the line image sensor 44 , in place of the pivot shaft 45 having a pivotal axis thereof positioned close to the longitudinal axis of the line image sensor 44 . This makes it possible to swing the line image sensor 44 about the pivot shaft 45 ′.
- the line image sensor 44 is configured to perform rotation or swing motion without performing linear motion. This makes the movement range of the line image sensor 44 smaller than that in a case where the line image sensor 44 is configured to perform linear motion, and hence it is possible to reduce the size of the image reading unit 62 ′.
- the pivotal axis exists as fixed points of the line image sensor 44 , so that by leading a signal line from an area close to the fixed point, it is possible to prevent occurrence of a trouble due to a disconnection as a problem to be solved when using such an apparatus that has a cable led out from the movable part thereof.
- FIG. 19 is a schematic side view of an image reading apparatus according to a third embodiment of the present invention. It should be noted that the arrangement of the image reading apparatus in FIG. 19 is schematically illustrated by way of example, and hence this is not limitative.
- the image reading apparatus 1 ′′ is comprised of a pickup roller 2 ′′ that picks up originals D, a feed roller 3 ′′ that feeds the originals D picked up by the pickup roller 2 ′′ into the apparatus 1 ′′, a retard roller 4 ′′ that separates the picked-up originals D one by one, a registration roller pair 5 ′′ provided for conveying the originals D, a contact glass 15 ′′ for guiding each original D to an image reading location 15 a on an original conveying surface thereof, a reference member 17 ′′ provided as a white reference in a reference member reading location 8 b on the original conveying surface of the contact glass 15 ′′, and a line image sensor 11 ′′ that reads image information on the original D through the contact glass 15 ′′. Further, the image reading apparatus 1 ′′ has a convey roller pair 7 ′′ disposed downstream of the line image sensor 11 ′′.
- the image reading apparatus 1 ′′ is formed by an upper frame 81 ′′ and a lower frame 82 ′′, and the line image sensor 11 ′′ is supported in the lower frame 82 ′′ in a manner movable between the image reading location 15 a and the reference member reading location 8 b.
- the image reading apparatus 1 ′′ performs the following operation for reading images on respective original D.
- the image reading apparatus 1 ′′ causes a drive mechanism, not shown, to move the line image sensor 11 ′′ in a direction indicated by an arrow b from a position opposed to the image reading location 15 a , and reads the reference member 17 ′′ by the line image sensor 11 ′′ through the contact glass 15 ′′ when the line image sensor 11 ′′ is brought to a position opposed to the reference member reading location 8 b .
- a portion of the lower surface of the reference member 17 ′′ corresponding to the reference member reading location 8 b and the vicinity of the portion provide the reference surface.
- Shading correction data generated based on an output from the line image sensor 11 ′′ having read the reference member 17 ′′ is stored on a pixel-by-pixel basis. Thereafter, the image reading apparatus 1 ′′ causes the drive mechanism, not shown, to return the line image sensor 11 ′′ to the home position i.e. the image reading location 15 a.
- the image reading apparatus 1 ′′ takes in the originals D by the pickup roller 2 ′′ and the feed roller 3 ′′, and separates the originals D, one by one, by the retard roller 4 ′′. While being nipped and conveyed (sub-scanned) by the registration roller pair 5 and the convey roller pair 7 , each original D has image information on its lower surface read by the line image sensor 11 ′′ in a main scanning direction (i.e. in a direction substantially orthogonal to the original conveying direction). During the image reading operation, image data generated based on an output from the line image sensor 11 ′′ is subjected to shading correction with reference to the aforementioned shading correction data. After image reading is completed, the original D which nipped and conveyed by the convey roller pair 7 ′′ is discharged out of the apparatus 1 ′′.
- FIG. 20 is a schematic side view of the reference member 17 ′′ appearing in FIG. 19 .
- the reference member 17 ′′ is comprised of a white film 71 formed on the original conveying surface of the contact glass 15 ′′ by silk printing (a kind of coating method) and a tape member (adhesive tape) 72 having one adhesive face and affixed to the upper surface of the white film 71 so as to prevent the white film 71 from being worn by contact with conveyed originals D.
- the tape member 72 there is used a member which looks white as viewed from the adhesive-face side.
- a light source incorporated in the line image sensor 11 ′′ irradiates light onto the white film 71 through the contact glass 15 ′′
- the tape member 72 reflects only light having passed through the white film 71 .
- the whiteness of the reference member 17 ′′ becomes uniform.
- the white film 71 is formed on the surface of the contact glass 15 ′′ by silk printing, other methods, such as painting or spray painting (also included in coating method), may be employed to form the white film 71 on the surface of the contact glass 15 ′′.
- the contact glass 15 ′′ may be subjected to surface processing e.g. for roughening the surface of the contact glass 15 ′′ so as to obtain excellent adhesion of the white film 71 to the contact glass 15 ′′.
- the reference member 17 ′′ is formed by affixing the white tape member 72 to the white film 71 , it suffices that the color of the tape member 72 is substantially white. Further, as shown in FIG. 21 , the reference member 17 ′′ may be formed by affixing a sheet form member 74 as a protective member to the white film 71 using a double-sided adhesive tape 73 . In this case, when the sheet form member 74 is substantially white, a transparent or white double-sided adhesive tape 73 is used, and when the sheet form member 74 has a color other than white, a substantially white double-sided adhesive tape 73 is used.
- the sheet form member 74 may be bonded to the white film 71 by an adhesive. In this case, however, it is required to use a substantially white sheet form member 74 so as to reduce the influence of non-uniform application of the substantially white adhesive. And transparent adhesive also require to use substantially white sheet form member 74 .
- the sheet form member 74 may be formed by a member of sheet metal, such as stainless, so as to suppress wear of the sheet form member 74 due to rubbing with originals.
- a sheet metal member having a sufficient thickness is used, the sheet metal member is fixed to a member other than the contact glass 15 ′′, and hence it is not required to affix or bond the sheet form member 74 to the white film 71 . In this case, it is more suitable if the lower surface of the sheet metal is machined so as to cause diffuse reflection of light. Further, a substantially white sheet or film may be provided on the lower surface of the sheet metal. Even when a sheet metal is laid on a white film, as mentioned above, and no affixing or bonding to the white film is effected, the combination of the white film and the sheet metal should be considered to be included in the category of the reference member 17 ′′.
- the sheet form member 74 may be fixed by affixing the double-sided adhesive tape 73 to a portion of the white film 71 or the contact glass 15 ′′ around the vicinity of the reference member reading location 15 a without affixing the double-sided adhesive tape 73 to the white film 71 in the vicinity of the reference member reading location 15 a .
- the double-sided adhesive tape 73 can have any color.
- the protective member such as the metal plate or the sheet metal member, is not required to cover the whole of the white film 71 , but it suffices that the protective member covers at least a portion thereof corresponding to reading position of the line image sensor 11 ′′ in the reference member reading position.
- the image reading apparatus 1 ′′ may be configured such that the line image sensor 11 ′′ is fixed and the contact glass is movable, or both can be moved.
- the present invention can also be applied to a flat bed scanner provided with an original conveying function.
- the image reading apparatus 1 ′′ may be configured such that the line image sensor 11 ′′ can move its reading position not by transition or parallel displacement but by performing rotation or other motion.
- the object of the present invention may also be accomplished by supplying a system or an apparatus with a storage medium in which a program code of software, which realizes the functions of either of the above described embodiments is stored, and causing a computer (or CPU or MPU) of the system or apparatus to read out and execute the program code stored in the storage medium.
- the program code itself read from the storage medium realizes the functions of either of the above described embodiments, and therefore the program code and the storage medium in which the program code is stored constitute the present invention.
- Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, a magnetic-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, a DVD-RW, a DVD+RW, a magnetic tape, a nonvolatile memory card, and a ROM.
- the program may be downloaded via a network.
Abstract
An image reading apparatus which is capable of performing accurate shading correction with simple arrangement while preventing a reference member from being scratched and paper powder and the like dust from being deposited on the reference member. The image reading apparatus comprises an image reading unit. In the image reading unit, a contact glass guides an original on an image reading location. The contact glass is held by a glass holding member. A line image sensor reads the image on the original conveyed on the image reading location, through the contact glass. The image reading unit further comprises a reference member whose image is readable by the image sensor, and a moving mechanism to move the image sensor so as to enable the image sensor to alternatively read the original and a reference surface of the reference member.
Description
- 1. Field of the Invention
- The present invention relates to an image reading apparatus configured to read an image formed on an original, while conveying the original, an image reading unit thereof, and a reference member thereof for shading correction.
- 2. Description of the Related Art
- In general, in an image reading apparatus configured to read an image formed on an original, while conveying the original, the original is illuminated with light from a light source, and reflected light from the original is focused by a rod lens array or the like, whereby the image on the original is read e.g. by a line image sensor. However, due to variations in the amounts of light from the light source and the variations in the performance of the rod lens array and variations in the sensitivity of the line image sensor, it is impossible to perform uniform image reading without any correction.
- To enable uniform image reading, image data obtained from an output signal from the line image sensor when an original image is read is corrected using shading correction data formed based on an output signal from the line image sensor obtained when a white reference member is read. When correction data for use in the correction is captured, light amount adjustment for optimizing the amount of light emitted from the light source to illuminate an original, and gain adjustment for optimizing an amplification factor for amplifying image signal output from the line image sensor are carried out. Further, it is a general practice to perform shading correction for correcting the variations in the amounts of light from the light source and the variations in the performance of the rod lens array and the variations in the sensitivity of the line image sensor in association with each pixel thereof. Hereafter, the correction including the light amount adjustment and the gain adjustment performed so as to enable the line image sensor to uniformly read image information from the original will be referred to as “shading correction”.
- In an image reading apparatus of the above-mentioned type, a member disposed in an original image reading position where the line image sensor reads an image on an original, for supporting a conveyed original from the reverse side of the same original has a color (black in general) other than white for the purpose of detection of a boundary between the original image and the background image, detection of a skew-feeding of the original, and prevention of lack of hiding of a reverse side image of the original.
- A description will be given of the schematic arrangement and operation of a conventional typical image reading apparatus with reference to
FIG. 22 . - The
image reading apparatus 1000 shown inFIG. 22 is configured to read image information on an original D by aline image sensor 110 through acontact glass 150 while conveying the original D. Theimage reading apparatus 1000 includes apickup roller 2 for picking up originals D, afeed roller 3 for feeding the originals D picked up by thepickup roller 2, aretard roller 4 for separating the picked-up originals D one from another, and aregistration roller pair 5 and aconvey roller pair 7 each formed by a pair of rollers disposed at respective opposed locations, for conveying the originals D. - First, before reading an image on an original D, the
image reading apparatus 1000 moves theline image sensor 110 in a direction indicated by an arrow S inFIG. 18 and causes theline image sensor 110 to read areference member 170. Thereference member 170 is disposed at a location opposed to theline image sensor 110 having been moved in the direction indicated by the arrow S. - Then, image data obtained based on an output from the
line image sensor 110 when theline image sensor 110 has read thereference member 170 is stored, as shading correction data for shading correction, in association with each pixel of theline image sensor 110. Thereafter, theimage reading apparatus 1000 returns theline image sensor 110 to its original position (original image reading position), and causes theline image sensor 110 to read the image on the original D, while conveying the original D. During the operation for reading the original D, the image data obtained from the output of theline image sensor 110 is corrected by shading correction performed with reference to the correction data stored in advance. It should be noted that whether or not theline image sensor 110 has been moved to a reference member reading position for reading thereference member 170 can be determined based on an output from aposition sensor 120. Theposition sensor 120 is a means for detecting the position of theline image sensor 110. - In the
image reading apparatus 1000 configured as above, if theline image sensor 110 deviates from the exact original image reading position when theline image sensor 110 returns from the reference member reading position to the original image reading position, registration error occurs in original reading. This registration error is generally prevented by positioning theline image sensor 110 using theposition sensor 120. The above-described sequential operation is commonly performed in response to an instruction from a control means, such as a CPU (Control Processing Unit). - Some image reading apparatuses are configured such that not a line image sensor but a reference member is moved between original reading position and escape position. For example, a technique has been proposed in which the reference member is exposed into an original conveying path during a period of reference member reading, and is retracted to a position where the reference member does not contact with a conveyed original, during a period of original reading (see e.g. Japanese Laid-Open Patent Publication (Kokai) No. 2005-102017).
- Conventionally, the reference member is disposed on the far side of the original conveying path from the line image sensor, at a location which enables the line image sensor to read the reference member.
- However, in the above-described prior art, paper powder and the like dust comes to stay between the reference member and the line image sensor as originals are conveyed, to make the reference member soiled, which can often hinder accurate shading correction. In such a case, a shading mechanism originally configured to correct the variations in the sensitivity of the line image sensor and the variations in the amount of light emitted from the light source and the variations in the performance of the lens array cannot operate accurately, causing variations in color and brightness in a read image. This is a serious problem for an image forming apparatus.
- For this reason, when accurate shading correction cannot be performed on images due to the above-mentioned soiling, a first countermeasure is conventionally taken in which a user cleans the reference member, and then reading is resumed.
- Further, a second countermeasure has conventionally been proposed in which the reference member is disposed at a location which does not face the original conveying path and where dust and dirt are difficult to attach, and the reference member is moved to a reading position of the line image sensor when acquisition of shading correction data is performed using the line image sensor (see e.g. Japanese Laid-Open Patent Publications (Kokai) No. H10-304195 and No. 2005-102017).
- A conventional image reading apparatus of another type has an image reading unit which causes the
line image sensor 110 to slidably move in a direction parallel to thecontact glass 150 thereby enable the reading position of the image sensor to move between the original reading position and the reference member reading position. This type of image reading apparatus reads image information from an original D by theline image sensor 110 through thecontact glass 150 while conveying the original D in a direction indicated by an arrow ‘a’ inFIG. 23 . During this operation, a light source incorporated in theline image sensor 110 illuminate the original D through thecontact glass 150. First, before starting the reading of the original D, the image reading apparatus moves theline image sensor 110 in a direction indicated by an arrow b inFIG. 23 , and causes the same to read a surface (reference surface), which faces thecontact glass 150, of thereference member 170. Then, the image reading apparatus generates shading correction data for use in shading correction, based on a signal output from theline image sensor 110 having read the reference surface, and stores the generated shading correction data on a pixel-by-pixel basis. - Thereafter, the image reading apparatus returns the
line image sensor 110 to its original position to read the image on the original D while conveying the original D in the direction of the arrow a. During this image reading operation, the image reading apparatus performs shading correction on image data generated based on an output signal from theline image sensor 110, by referring to the shading correction data stored in advance. - The
reference member 170 used here is implemented e.g. by a white film formed by silk printing or the like. - Japanese Laid-Open Patent Publication (Kokai) No. S62-098861 discloses a flat bed scanner which uses the aforementioned white film as the reference member.
- The image reading apparatus disclosed in
- Japanese Laid-Open Patent Publication (Kokai) No. 2005-102017 is advantageous in that originals do not rub against the reference member during conveyance, and hence the reference member is difficult to be scratched or soiled. However, paper powder produced and wafted during an original conveying period can be deposited on the reference member, which necessitates periodic cleaning of the reference member. In addition, since paper powder is very fine, it is difficult to remove the paper powder deposited on the reference member completely. Further, a mechanism for causing the reference member to be exposed to the original conveying path is necessitated, which can cause an increase in the number of component parts and make the construction of the apparatus complicated.
- On the other hand, in the conventional image reading apparatus shown in
FIG. 22 , since an original D rubs against thereference member 170 during conveyance, thereference member 170 can be scratched, or dust, such as paper powder and swarf from rollers, can be attached to thereference member 170. Therefore, if shading correction is performed with reference to thereference member 170 deprived of whiteness by being scratched or soiled, lines or streaks appear on read original images. - Insofar as the first countermeasure is concerned, image degradation due to maladjustment of shading correction cannot be recognized until the read image is viewed. For this reason, in a case where a large number of originals are continuously read, it is difficult to recognize image degradation at an early stage of the reading operation, and it is only after a long time that the reading operation is restarted. Further, the user has to clean the reference member manually, which is a nuisance to the user.
- On the other hand, in the case of the second countermeasure, a traveling path along which the reference member extends continuous with the original conveying path and a standby location of the reference member, and hence a tiny amount of dust, such as paper powder, produced by conveyance of originals can enter the traveling path and stay thereon. In this case, there is a fear that the reference member moved into the original conveying path for shading correction might be soiled by the remaining dust.
- Further, white films formed by coating (painting or printing) are liable to differ in thickness between individual units thereof, and even an individual white film is apt to have variation in thickness depending on the location thereon. The use of such a white film as a white reference leads to a single image which is partially degraded due to partial degradation of the image reading performance or occurrence of an image reading apparatus degraded in image reading performance.
- The present invention provides an image reading apparatus which is capable of performing accurate shading correction with simple arrangement while preventing a reference member from being scratched and paper powder and the like dust from being deposited on the reference member, and an image reading unit thereof, as well as a shading correction reference member thereof.
- In a first aspect of the present invention, there is provided an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to move the image sensor so as to enable the image sensor to alternatively read the original conveyed on the image reading location and the reference member, wherein arrangement of the image sensor and the reference member is so designed as to make the reference surface of said reference member isolated from the conveying path.
- With the arrangement of the first aspect of the present invention, the image sensor and the reference member are arranged such that the reference surface of the reference member is isolated from the conveying path. More specifically, the reference member is provided on the original conveying path-side surface of the contact glass. Further, the reference surface of the reference member is held in close contact with the contact glass. As a consequence, it is possible to perform accurate shading correction with the simple arrangement while preventing the reference member from being scratched and paper powder and the like dust from being attached to the reference member.
- The reference surface of the reference member can be held in close contact with the contact glass.
- The reference member can be disposed on the glass holding member.
- With the arrangement of this embodiment, the reference member can be disposed on the glass holding member. As a consequence, in a state isolated from the conveying path, the reference surface of the reference member can be protected from being soiled by paper powder and the like dust. Therefore, it is possible to perform accurate shading correction and dispense with cleaning of the reference member.
- In a second aspect of the present invention, there is provided an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to relatively move the image sensor and the reference member so as to enable the image sensor to alternatively read the original conveyed to the image reading location and the reference member, wherein arrangement of the image sensor and the reference member is so designed as to make the reference surface isolated from the conveying path, and the reference member is disposed on an original conveying path-side surface of the contact glass.
- With the arrangement of the second aspect of the present invention, it is possible to obtain the same advantageous effects as provided by the first aspect of the invention.
- In a third aspect of the present invention, there is provided an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to relatively move the image sensor and the reference member so as to enable the image sensor to alternatively read the original conveyed on the image reading location and the reference member, wherein arrangement of the image sensor and the reference member is so designed as to make the reference surface isolated from the conveying path, and the reference member is fixed to an opposite surface of the contact glass from an original conveying path-side surface thereof.
- With the arrangement of the third aspect of the invention, the reference member is fixed to the opposite surface of the contact glass from the original conveying path-side surface thereof. As a consequence, in a state isolated from the conveying path, the reference surface of the reference member is protected from being soiled by paper powder and the like dust. Therefore, it is possible to perform accurate shading correction and dispense with cleaning of the reference member.
- In a fourth aspect of the present invention, there is provided an image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold the contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through the contact glass, a reference member whose image is readable by the image sensor, and a moving mechanism configured to relatively move the image sensor and the reference member so as to enable the image sensor to alternatively read the original conveyed on the image reading location and the reference member, wherein the reference member comprises a white coating film formed on an original conveying path-side surface of the contact glass, and a protective member covering at least a portion of the white coating film, for protection of the white coating film.
- With the arrangement of the fourth aspect of the present invention, it is possible to obtain the same advantageous effects as provided by the first aspect of the invention.
- In a fifth aspect of the present invention, there is provided an image reading apparatus configured to read an image formed on an original, comprising an image reading unit including a frame that has an opening formed in an original conveying path side thereof, and rotatably supports a pivot shaft of an image sensor housed in the frame, a contact glass disposed on the opening of the frame, configured to guide the original to an image reading location thereon, and a reference member disposed within the frame.
- With the arrangement of the fifth aspect of the present invention, the image reading unit provided in the image reading apparatus includes a frame that has an opening formed in an original conveying path side thereof, and rotatably supports a pivot shaft of an image sensor housed in the frame, a contact glass disposed on the opening of the frame, for guiding the original to an image reading location thereon, and a reference member disposed within the frame. Therefore, it is possible to prevent paper powder and the like dust attached to the upper surface of the contact glass i.e. attached to originals being conveyed out of the frame from entering the frame and from attaching to the white reference member. Thus, accurate shading correction can be achieved without necessitating cleaning of the reference member.
- In a sixth aspect of the present invention, there is provided an image reading unit provided in the image reading apparatus according to the fifth aspect of the present invention.
- With the arrangement of the sixth aspect of the present invention, it is possible to obtain the same advantageous effects as provided by the first aspect of the invention.
- In a seventh aspect of the present invention, there is provided an image reading apparatus for reading an image formed on an original, while conveying the original, comprising a contact glass configured to have an original conveying surface on which an original reading position and a reference member reading position exist, and guide the original on the original conveying surface, an image sensor configured to be capable of moving a reading position thereof between the original reading position and the reference member reading position, and read the image formed on the original guided on the original conveying surface, through the contact glass, and a shading correction reference member as a white reference for the image sensor, wherein the shading correction reference member comprises a white coating film formed on an original conveying path-side surface of the contact glass, and a protective member covering at least a portion of the white coating film, for protection of the white coating film.
- With the arrangement of the seventh aspect of the present invention, the reference member is formed by affixing the protective member, such as a white tape, to the white coating film, so that even if the thickness of the white coating film formed by painting or printing method is not uniform, the protective member, such as a white tape, or the two-sided tape for affixing the protective member to the white coating film functions like a back light to reflect light having passed through the white coating film, which makes it possible to maintain uniform whiteness of the reference member, as viewed through the contact glass. This enhances accuracy in shading correction, and therefore it is possible to maintain stable image reading performance. Further, the white coating film does not require high hardness and is allowed to have a non-uniform thickness, so that it is possible to form the white coating film by an inexpensive method. The protective member suffices if only it can reflect light having passed through the white coating film, and is not required to be formed high dimensional accuracy. When a durable protective member formed e.g. of metal is used, it is not necessary to carry out replacement of the protective member, which provides an image reading apparatus that is easy to manufacture and maintain.
- The protective member can be a substantially white adhesive tape.
- The protective member can be substantially white, and the shading correction reference member can have a transparent fixing member provided between the protective member and the white coating film, for fixing the protective member to a surface of the white coating film.
- The shading correction reference member can have a substantially white fixing member provided between the protective member and the white coating film, for fixing the protective member to a surface of the white coating film.
- The shading correction reference member has a two-sided adhesive tape for fixing the protective member, in a manner opposed to the white coating film, to at least one of a portion of the white coating film and a portion of the contact glass other than a portion close to the reference member reading location.
- The fixing member can be a two-sided adhesive tape.
- The fixing member can be an adhesive.
- The protective member can be a sheet form member.
- The protective member is a sheet metal member.
- In an eighth aspect of the present invention, there is provided a shading correction reference member disposed at a reference member reading location on a contact glass provided in an image reading apparatus, comprising a white coating film formed on an original conveying path-side surface of the contact glass, and a protective member covering at least a portion of the white coating film, for protection of the white coating film.
- With the arrangement of the eighth aspect of the present invention, it is possible to obtain the same advantageous effects as provided by the seventh aspect of the invention.
- The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.
-
FIG. 1 is a schematic side cross-sectional view showing the internal construction of an image reading apparatus according to a first embodiment of the present invention. -
FIG. 2 is a schematic block diagram showing the electrical configuration of the image reading apparatus inFIG. 1 . -
FIGS. 3A and 3B are cross-sectional views of an image reading unit appearing inFIG. 1 , in a state during an original reading period, in which: -
FIG. 3A shows the image reading unit as viewed vertically; and -
FIG. 3B shows the image reading unit as viewed horizontally. -
FIGS. 4A and 4B are cross-sectional views of the image reading unit in a state during a reference member reading period, in which: -
FIG. 4A shows the image reading unit as viewed vertically; and -
FIG. 4B shows the image reading unit as viewed horizontally. -
FIGS. 5A and 5B are views of a drive section appearing inFIG. 1 and component parts associated therewith as viewed from above, in which: -
FIG. 5A shows a state during the original reading period; and -
FIG. 5B shows a state during the reference member reading period. -
FIGS. 6A and 6B are views of the drive section and component parts associated therewith, as viewed in an original conveying direction, in which: -
FIG. 6A shows a state in which the apparatus is closed during the original reading period; and -
FIG. 6B shows a state in which the apparatus is open during the reference member reading period. -
FIG. 7 is a diagram showing an output waveform obtained when an image reading operation is performed by a line image sensor while a pulse motor is rotated at a constant speed. -
FIGS. 8A and 8B are partial vertical cross-sectional views showing another example of the image reading unit, in which: -
FIG. 8A shows a state during the original reading period; and -
FIG. 8B shows a state during the reference member reading period. -
FIGS. 9A and 9B are partial vertical cross-sectional views showing still another example of the image reading unit, in which: -
FIG. 9A shows a state during the original reading period; and -
FIG. 9B shows a state during the reference member reading period. -
FIGS. 10A to 10D are partial cross-sectional views showing an example of the layout of a reference member, in which: -
FIG. 10A shows a case where the reference member is disposed on an opposite surface of a contact glass from an original conveying surface thereof; -
FIG. 10B shows a case where the reference member is disposed on an original conveying surface of a glass holding member; -
FIG. 10C shows a case where the reference member is disposed on an opposite surface of the glass holding member from the original conveying surface thereof; and -
FIG. 10D shows a case where a junction part is omitted from the layout shown inFIG. 10B . -
FIG. 11 is a schematic view of an image reading apparatus according to a second embodiment of the present invention. -
FIG. 12 is a schematic view of a variation of the image reading apparatus inFIG. 11 . -
FIG. 13 is a schematic view of another variation of the image reading apparatus inFIG. 11 . -
FIG. 14 is a schematic view of a line image sensor provided in an image reading unit appearing inFIG. 11 . -
FIGS. 15A and 15B are cross-sectional views showing the image reading unit and its surrounding, in which: -
FIG. 15A shows a state during the original reading period; and -
FIG. 15B shows a state during a shading correction data acquisition period. -
FIG. 16 is a perspective view of the image reading unit. -
FIG. 17 is a flowchart of a shading correction process executed by a CPU. -
FIGS. 18A and 18B are cross-sectional views showing the image reading unit according to a variation and its surrounding, in which: -
FIG. 18A shows a state during the original reading period; and -
FIG. 18B shows a state during the shading correction data acquisition period. -
FIG. 19 is a schematic side view of an image reading apparatus according to a third embodiment of the present invention. -
FIG. 20 is a schematic side view of a reference member appearing inFIG. 19 . -
FIG. 21 is a schematic side view of a variation of the reference member inFIG. 20 . -
FIG. 22 is a side view showing the internal construction of a conventional image reading apparatus. -
FIG. 23 is a schematic side view of an image reading unit of the conventional image reading apparatus. - The present invention will now be described in detail with reference to the drawings showing preferred embodiments thereof. It should be noted that the relative arrangement of the components, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise.
-
FIG. 1 is a schematic side cross-sectional view showing the internal construction of an image reading apparatus according to a first embodiment of the present invention. The arrangement of the image reading apparatus shown inFIG. 1 is given only by way of example, but it is not limitative. - As shown in
FIG. 1 , theimage reading apparatus 1 is comprised of apickup roller 2 that picks up originals D, afeed roller 3 that feeds the originals D picked up by thepickup roller 2 into theapparatus 1, aretard roller 4 that separates the picked-up originals D one by one, a pair ofregistration rollers 5 disposed at respective locations opposed to each other for conveying an original D, animage reading unit 61 that reads image information on the upper surface (surface on a front side) of each original D conveyed by theregistration roller pair 5, animage reading unit 62 that reads image information on the lower surface (surface on a reverse side) of each conveyed original D, and a pair of conveyrollers 7 disposed at respective locations downstream of theimage reading units - The
image reading apparatus 1 has anupper frame 81 pivotally movable about apivot shaft 81 a and alower frame 82 supporting thepivot shaft 81 a, and coveys the original D through a space enclosed by theupper frame 81 and thelower frame 82. Theupper frame 81 can be turned (opened/closed) manually so as to allow an original D conveyed and jammed in theapparatus 1 to be removed from theapparatus 1. - The
upper frame 81 accommodates thefeed roller 3, one of theregistration rollers 5, theimage reading unit 61, and one of the conveyrollers 7, while thelower frame 82 accommodates theretard roller 4, the other one of theregistration rollers 5, theimage reading unit 62, and the other one of the conveyrollers 7. Portions (not shown) supporting thepivot shaft 81 a are integrally formed with thelower frame 82, and extend from the respective sides (toward and away from the viewer viewingFIG. 1 ) in a manner sandwiching theupper frame 81. - The
image reading unit 62 is fixed to thelower frame 82. On the other hand, theimage reading unit 61 is movably supported on theupper frame 81 by a plurality ofswing arms 9. Each of theswing arms 9 has one end thereof supported on theupper frame 81, and the other end thereof supported on theimage reading unit 61. This makes theimage reading unit 61 vertically movable, so that reading of an image on a thick original and conveyance of the thick original can be performed smoothly. The one end of eachswing arm 9 has a snap-fit structure, which facilitates assembly. - A driving
unit 10 is comprised of a drive mechanism and a drive motor accommodated in the vicinity of the portions of thelower frame 82 supporting thepivot shaft 81 a, for driving the protrudingportions respective slide cams 18 that protrude from the side surfaces of the respectiveimage reading units FIG. 1 ). The pushingmember 19 presses the protrudingportions image reading units - Next, a description will be given of a sequence of operations carried out by the
image reading apparatus 1 for reading an image on an original D. - First, the pushing
member 19 as one of component parts forming the drivingunit 10 is caused to press the protrudingportions image reading units image reading apparatus 1 generates shading correction data, based on reading signals obtained by the reading, and stores the generated shading correction data on a pixel-by-pixel basis. Thereafter, pressing of the protrudingportions member 19 is stopped, and then originals D are fed into theapparatus 1 by thepickup roller 2 and thefeed roller 3 and are separated one by one by theretard roller 4. - While being nipped and conveyed (in a sub-scanning direction) by the
registration roller pair 5 and the conveyroller pair 7, each original D is repeatedly scanned by theimage reading units image reading units roller pair 7 and discharged out of theapparatus 1. Generation and storage of the shading correction data may be performed once for all loaded originals D at the start of reading operation or may be repeatedly performed for every several originals D. -
FIG. 2 is a schematic block diagram showing the electrical configuration of theimage reading apparatus 1 inFIG. 1 . - In
FIG. 2 ,reference numeral 11 designates the line image sensor (image sensor) provided in each of theimage reading units Reference numeral 111 designates a light source incorporated in theline image sensor 11. -
Reference numeral 100 designates an A/D converter section that performs analog processing, such as amplification and black level clamp, on the image signals received from the respectiveline image sensors 11 and then A/D converts the signals.Reference numeral 101 designates an image processing section that controls theline image sensors 11, thelight sources 111, the A/D converter section 100, and so forth, and performs various kinds of image processing (including shading correction) on image data obtained by A/D conversion of the image signals. -
Reference numeral 102 designates an image storage section (image memory) that stores image data.Reference numeral 103 designates an interface section that connects theimage processing section 101 to an external host apparatus, a network, and so forth via asignal line 109.Reference numeral 104 designates a control section (CPU) that controls the overall operation of theimage reading apparatus 1.Reference numeral 105 designates a storage section (working memory) used by theCPU 104 for operation. - The
image processing section 101, theCPU 104, and the workingmemory 105 are interconnected by abus 108. TheCPU 104 is configured to be able to access theimage memory 102 via theimage processing section 101. Therefore, theCPU 104 can perform processing using image data stored in theimage memory 102, according to a program written in the workingmemory 105. -
Reference numeral 112 designates a conveying motor for conveying originals D. The conveyingmotor 112 operates under the control of amotor driver 107 responsive to an instruction from theCPU 104. Apulse motor 21 is one of the component parts forming the drivingunit 10. Thepulse motor 21 causes rotating motion of the pushingmember 19 to thereby slide theslide cam 18, whereby each of theline image sensors 11 is moved between an original image reading position for reading an image on an original D and a reference member reading position for reading the reference member. Thepulse motor 21 operates under the control of amotor driver 106 responsive to an instruction from theCPU 104. - Next, the arrangement of the
image reading unit 62 appearing inFIG. 1 will be described with reference toFIGS. 3A and 3B andFIGS. 4A and 4B . -
FIG. 3A is a vertical partial cross-sectional view of theimage reading unit 62 during the original reading period, whileFIG. 3B is a horizontal partial cross-sectional view of the same.FIG. 4A is a vertical partial cross-sectional view of theimage reading unit 62 during the reference member reading period, whileFIG. 4B is a horizontal partial cross-sectional view of the same. Theimage reading unit 61 and theimage reading unit 62 are identical in construction, and hence a description will be given of theimage reading unit 62 alone. - As shown in
FIGS. 3A and 3B andFIGS. 4A and 4B , theimage reading unit 62 is comprised of theline image sensor 11 that reads images, aframe 12 that accommodates theline image sensor 11, a printedcircuit board 13 that causes theline image sensor 11 to operate, aflat cable 14 that connects between theline image sensor 11 and the printedcircuit board 13, acontact glass 15 that guides an original D to an originalimage reading location 15 a, aglass holding member 16 that holds thecontact glass 15, thereference member 17 having a white reference surface, theslide cam 18 that moves theline image sensor 11 to a predetermined position, and atension spring 22 that urges theslide cam 18 to return theline image sensor 11 from the predetermined position to its home position. - As shown in
FIGS. 3A and 4A , theframe 12 is formed with a throughhole 12 a through which theflat cable 14 extends. The throughhole 12 a is formed to have an eaves shape so as to prevent the entry of dirt and dust. - The
reference member 17 is disposed on the original conveying surface of thecontact glass 15 at a location different from the originalimage reading location 15 a. The white reference lower surface of thereference member 17, as a portion close to the location corresponding to the reference member reading position, is held in intimate contact with thecontact glass 15 by bonding, adhesion using an adhesive tape, or any other suitable method. Alternatively, thereference member 17 may be formed on thecontact glass 15 by coating (painting or printing). Therefore, the white reference surface is prevented from being damaged even when a conveyed original D rubs against thereference member 17, or from losing whiteness due to attachment of paper powder or dirt thereto. - The
line image sensor 11 hasprotrusions FIG. 3B . Theprotrusion 11 a is fitted in acam groove 18 a formed in theslide cam 18. Further, theprotrusion 11 a is fitted through anelongated hole 12 b formed in theframe 12, whereby the movement of theline image sensor 11 in the main scanning direction is restricted. On the other hand, theprotrusion 11 b is fitted in acam groove 18 b also formed in theslide cam 18. - The
slide cam 18 is formed with thecam grooves protrusions elongated holes frame 12 are fitted, respectively, and ahook part 18 e to which thetension spring 22 is hooked. - The
slide cam 18 is under tension by thetension spring 22 held on a holdingpart 12 e of theframe 12 by thetension spring 22 under tension acting in a direction indicated by an arrow f inFIGS. 3B and 4B . During the original reading period, as shown inFIG. 3B , the protrudingportion 18 y as one end of the slide cam 18 (the protrudingportion 18 x in the case of the image reading unit 61) is held in a state protruding from theframe 12. On the other hand, during the reference member reading period, as shown inFIG. 4B , the protrudingportion 18 y as one end of the slide cam 18 (the protrudingportion 18 x in the case of the image reading unit 61) is held in a state retracted in theframe 12 of theimage reading units 62. - The
slide cam 18 is thus slidably engaged with theline image sensor 11, and is driven in the main scanning direction i.e. the longitudinal direction of theline image sensor 11, whereby theline image sensor 11 can be moved according to the shapes of thecam grooves - Next, the arrangement of the driving
unit 10 appearing inFIG. 1 will be described with reference toFIGS. 5A and 5B andFIGS. 6A and 6B . -
FIGS. 5A and 5B are views of the drivingunit 10 and component parts associated therewith, as viewed from above, in whichFIG. 5A shows a state during the original reading period, andFIG. 5B shows a state during the reference member reading period. - As shown in
FIGS. 5A and 5B , the protrudingportion 18 x is an end portion of theslide cam 18 protruding from a side surface of theimage reading unit 62, and the protrudingportion 18 y is an end portion of theslide cam 18 protruding from a side surface of theimage reading unit 61. - The driving
unit 10 is comprised of the pushingmember 19 for pushing in the protrudingportions eccentric cam 20 for transmitting a driving force to the pushingmember 19, and thepulse motor 21 for rotating theeccentric cam 20 about apivot shaft 20 b to actuate the pushingmember 19. - The pushing
member 19 has acontact surface 19 a held in contact with an eccentriccylindrical surface 20 a of theeccentric cam 20, and thecontact surface 19 b for being brought into contact with the protrudingportions member 19 is configured such that thecontact surface 19 a held in contact with the eccentriccylindrical surface 20 a is pushed by the rotation of theeccentric cam 20 about the axis of thepivot shaft 20 b and is rotated about the axis of thepivot shaft 19 d. When the pushingmember 19 is rotated about thepivot 19 d, the ends of the slide cams 18 (protrudingportions image reading units image reading units - The
image reading unit 61 and theimage reading unit 62 are arranged such that the protrudingportion 18 x of theimage reading unit 61 is positioned farther from thepivot 19 d than the protrudingportion 18 y ofimage reading unit 62 so as to make a difference between the distance from thepivot 19 d to the protrudingportion 18 x and that from thepivot 19 d to the protrudingportion 18 y. Since theimage reading units member 19 is brought into contact with the protrudingportion 18 y as shown inFIG. 5A , but on the other hand, thecontact surface 19 b is kept from contact with the protrudingportion 18 x. As a consequence, theimage reading unit 61 movably supported by theswing arms 9 is allowed to vertically move smoothly in accordance with the varying thickness of originals. -
FIGS. 6A and 6B are views of the drivingunit 10 and component parts associated therewith, as viewed in the original conveying direction, in whichFIG. 6A shows a state in which theapparatus 1 is in closed state during the reference member reading period, andFIG. 6B shows a state in which theapparatus 1 is opened during the reference member reading period. - The state where the
apparatus 1 is closed is defined as a state in which theupper frame 81 and thelower frame 82 are held in meeting contact with each other as shown inFIG. 1 and the original conveying passage can normally function. On the other hand, the state where theapparatus 1 is open is defined as a state in which theupper frame 81 is in a lifted position by being turned upward around thepivot shaft 81 a, whereby the conveying passage is kept open for cleaning. - As shown in
FIGS. 6A and 6B , the pushingmember 19 has asloping surface part 19 c formed on a contact portion thereof facing toward theimage reading units portion 18 x. When theapparatus 1 is opened during the reference member reading period, since theslide cam 18 is under tension by thetension spring 22, the protrudingportion 18 x pressed in by the pushingmember 19 protrudes from theimage reading unit 61 in a state freed from the pressing force of the pushingmember 19. When theapparatus 1 is closed in this state, there is a fear that the protrudingportion 18 x and the pushingmember 19 collides with each other, causing breakage, unless thesloping surface part 19 c is not formed on the pushingmember 19. - However, according to the present embodiment, since the pushing
member 19 is formed with thesloping surface part 19 c, the protrudingportion 18 x protruding from theimage reading unit 61 is pressed in by being brought into abutment with thesloping surface part 19 c during the process of closing theapparatus 1, which makes it possible to prevent breakage due to collision between the protrudingportion 18 x and the pushingmember 19. It should be noted that by forming the end of the protrudingportion 18 x for contact with thesloping surface part 19 c to have a round shape (angle R), it is possible to further enhance the effect of preventing breakage due to collision between the protrudingportion 18 x and the pushingmember 19. - With this arrangement, the
image reading apparatus 1 can drive theslide cams 18 of the respective twoimage reading units single driving unit 10. This eliminates the need for providing each of the twoimage reading units apparatus 1. Further, it is possible to make the number of component parts of theapparatus 1 smaller than that of the conventional apparatus, thereby reducing the price of theapparatus 1. - Furthermore, the
slide cams 18 can be externally driven from outside the respectiveimage reading units line image sensor 11, so that in a case where the image reading apparatus is a single-sided reading apparatus, it is possible to form theapparatus 1 by theupper frame 81 accommodating an image reading unit and thelower frame 82 without an image reading unit, and provide the drivingunit 10 in thelower frame 82. Thus, the degree of freedom in configuration of theapparatus 1 can be enhanced. - Next, an operation for detecting an operation starting position of the
pulse motor 21 will be described with reference toFIG. 7 . -
FIG. 7 is a diagram showing an output waveform obtained when an image reading operation is performed by theline image sensor 11 while thepulse motor 21 is rotated at a constant speed. Specifically, the diagram shows changes in the output value common to light-receiving elements of theline image sensor 11 with respect to the number of steps of the pulse motor 21 (driving amount of the driving unit 10) counted when an image reading operation is performed by theline image sensor 11 while rotating thepulse motor 21 at a constant speed. - As the
pulse motor 21 is caused to perform one rotation, theline image sensor 11 moves from the position not opposed to thereference member 17 as shown inFIG. 3A to a position opposed to thereference member 17 as shown inFIG. 4A , and then returns to the position not opposed to thereference member 17 as shown inFIG. 3A . In the meantime, a reading operation is performed by theline image sensor 11, and the line image sensor output value as shown inFIG. 7 is stored in theimage memory 102. The line image sensor output value is obtained by converting the line image sensor output as an analog signal into digital data by the A/D converter section 100 and then subjecting the digital data to offset correction. - The
CPU 104 performs processing for detecting a boundary between image data obtained by reading thereference member 17 in the position opposed to thereference member 17 and image data read in the position not opposed to thereference member 17, from the image data stored in theimage memory 102. TheCPU 104 stores information on which pulse of thepulse motor 21 corresponds to the detected boundary, and calculates a desirable stop position, whereby it is possible to know the number of steps of thepulse motor 21 required for moving theline image sensor 11 from the current operation starting position to the original image reading position or the reference member reading position. This step count is equal to the driving amount of the drivingunit 10. - A midpoint (1) between a boundary (A) detected when the
line image sensor 11 has moved from a position not opposed to thereference member 17 as shown inFIG. 3A to a position opposed to thereference member 17 as shown inFIG. 4A and a boundary (B) detected when theline image sensor 11 has moved from the position opposed to thereference member 17 to a position which ceases to be opposed to thereference member 17 as shown inFIG. 3A can be regarded as an optimum position for causing theline image sensor 11 to be opposed to thereference member 17. - On the other hand, a midpoint (2) between the boundary (B) detected when the
line image sensor 11 has moved from the position opposed to thereference member 17 as shown inFIG. 4A to the position not opposed to thereference member 17 as shown inFIG. 3A and a boundary (C) detected when theline image sensor 11 has moved from the position not opposed to thereference member 17 to the position opposed to thereference member 17 as shown inFIG. 4A can be regarded as an optimum position for causing theline image sensor 11 to be not opposed to thereference member 17. - However, the size of the
reference member 17 varies with eachimage reading apparatus 1. Further, since the reading position of theline image sensor 11 is moved by thepulse motor 21 via the pushingmember 19 and theslide cam 18, the distance of travel of theline image sensor 11 varies. - To detect the optimum positions, the reading operation is performed while rotating the
pulse motor 21 at a constant speed, and driving amounts L1 and L2 of thepulse motor 21 required for moving theline image sensor 11 between the boundaries are each determined as respective step counts based on the changes in the output value shown inFIG. 7 . Thus, driving amounts L+L1′ and L+L1+L2′ of thepulse motor 21 required for moving theline image sensor 11 from the current operation starting position of thepulse motor 21 to the positions corresponding to the respective midpoints (1) and (2) can be each determined as respective step counts. - As described above, it is possible to calculate the driving amount for moving the
line image sensor 11 to the midpoint (1) as a driving amount for positioning theline image sensor 11 for the reference member reading operation and the driving amount for moving theline image sensor 11 to the midpoint (2) as a driving amount for positioning theline image sensor 11 for the original image reading operation, respectively. This eliminates the need for additionally providing a position sensor for detecting the operation starting position of theline image sensor 11. - Even when the
line image sensor 11 is moved to the position not opposed to thereference member 17, if an original D or the like exists on thecontact glass 15, the difference in brightness between the surface of the original D and that of thereference member 17 becomes so small that the boundaries cannot be detected. Therefore, in this case, an error message may be displayed to instruct or urge a user to remove the original D. - By the way, immediately after the power of the
image reading apparatus 1 is turned on, it is impossible to recognize the current stop position of thepulse motor 21. This means that the position of theline image sensor 11 cannot be determined. For this reason, neither the light amount adjustment of the light source nor the gain adjustment of the A/D converter section 100 can be performed at this time point. - Therefore, in the operation for searching for the boundaries detected when the
line image sensor 11 passing over an area including a portion opposed to thereference member 17 and a portion not opposed to thereference member 17, a light amount set value of the light source, a gain set value of the A/D converter section 100, and the shading correction data are each set to a preset initial value (particularly suitably, immediately after assembling theapparatus 1 in a factory, for example). In discriminating between a scan image read at “the optimum position for causing theline image sensor 11 to be opposed to the reference member 17 (the midpoint (1))” as mentioned above (hereinafter referred to as “the scan image from thereference member 17”) and a scan image read at the other optimum position for causing theline image sensor 11 to be not opposed to the reference member 17 (the midpoint (2))” as mentioned above (hereinafter referred to as “the scan image from the portion other thanreference member 17”), a method of utilizing the difference in magnitude between an output from theline image sensor 11 and a predetermined threshold value can be exemplified as an easy method to employ. - However, the influence of variation in the amount of light from the light source or the like can make it impossible to discriminate between the scan image from the
reference member 17 and that from the portion other than thereference member 17 using the preset initial values or the predetermined threshold value. In such a case, it is possible to employ a method of storing the maximum and minimum values of the output from theline image sensor 11 during one rotation of thepulse motor 21, and setting the average value of the maximum and minimum values to the threshold value, or a method of changing the light amount set value of the light source and the gain set value of the A/D converter section 100 such that discrimination between the scan image from thereference member 17 and that from the portion other than thereference member 17 can be performed based on a predetermined threshold value. The gain set value may be changed by adjusting an amplifier that amplifies an analog signal before A/D conversion, or by computing digital data after A/D conversion. - With the above-described arrangement, during the reference member reading period before execution of the image reading operation, the
image reading apparatus 1 rotates thepulse motor 21 to bring the pushingmember 19 and theslide cam 18 into the state shown inFIG. 5B , thereby moving theline image sensor 11 to the position opposed to the reference member 17 (seeFIG. 4A ). Then, when theline image sensor 11 and thereference member 17 are opposed to each other such that the reading effective range of theline image sensor 11 is covered by thereference member 17, theline image sensor 11 reads thereference member 17. As a consequence, correction data generated based on the output from theline image sensor 11 is stored on a pixel-by-pixel basis, as shading correction data for use in shading correction. Thereafter, theimage reading apparatus 1 rotates thepulse motor 21 to bring the pushingmember 19 and theslide cam 18 into the state shown inFIG. 5A , thereby moving theline image sensor 11 to the position not opposed to the reference member 17 (seeFIG. 3A ). - According to the above-described embodiment, the
line image sensor 11 and thereference member 17 are arranged such that the reference surface of thereference member 17 is isolated from the conveying path for originals D. More specifically, thereference member 17 is disposed on the original conveying surface of thecontact glass 15, with the reference surface thereof held in intimate contact with thecontact glass 15. This prevents the reference surface from being scratched, and prevents deposition of paper powder or the like, which obviates the necessity of cleaning thereference member 17. This makes it possible to acquire shading correction data without suffering from degradation of the whiteness of the reference surface, and perform shading correction with accuracy. - Although in the above-described embodiment, only the
line image sensor 11 is moved, this is not limitative. More specifically, theline image sensor 11 and theglass holding member 16 may be relatively moved to thereby shift theline image sensor 11 between the position opposed to thereference member 17 and the position not opposed to thereference member 17. For example, the image reading unit may be configured such that only theglass holding member 16 is moved during a transition period between the original reading period shown inFIG. 8A and the reference member reading period shown inFIG. 8B , or alternatively such that theline image sensor 11 and theglass holding member 16 are both moved during the transition period between the original reading period shown inFIG. 9A and the reference member reading period shown inFIG. 9B . - Further, although in the above-described embodiment, the
reference member 17 is provided on the original conveying surface of thecontact glass 15, this is not limitative. More specifically, thereference member 17 can be disposed at any location on thecontact glass 15 or on theglass holding member 16 insofar as it is off the originalimage reading location 15 a. For example, as shown inFIG. 10A , thereference member 17 may be disposed on the opposite side of thecontact glass 15 from the original conveying surface thereof. Alternatively, thereference member 17 may be disposed on the original conveying surface of theglass holding member 16 as shown inFIG. 10B , or on the opposite side of theglass holding member 16 from the original conveying surface of the same as shown inFIG. 10C . In the case shown inFIG. 10B , theline image sensor 11 has to move over ajunction part 16 a connecting between thecontact glass 15 and thereference member 17, which increases the distance of travel of theline image sensor 11. Therefore, thejunction part 16 a may be omitted as shown inFIG. 10D . - The
reference member 17 disposed as shown inFIGS. 10B and 10D requires sufficient strength and thickness for preventing the white reference surface thereof from being damaged by conveyed originals D. In the cases shown inFIGS. 10A and 10C , the white reference surface of thereference member 17 and the upper surface of thecontact glass 15 as the surface for reading originals D are different in location from each other, and hence it is desirable to select a thickness of thecontact glass 15 and a shape of theglass holding member 16 such that the surfaces of the two are both brought into focus. This is because one of unevenesses which must be corrected by shading correction is variation in the amount of light from a rod lens array (not shown), but the profile of the variation in the light amount (i.e. light amount distribution profile) becomes different in a position away from a position in focus, which makes the shading correction inaccurate. When the variation in the amount of light from the rod lens array is small, the reference member reading operation can be performed in a position out of focus. - In the cases in
FIGS. 10A and 10D as well, insofar as theline image sensor 11 can be eventually moved between the position opposed to thereference member 17 and the position not opposed to thereference member 17, it doesn't matter whether theline image sensor 11, thereference member 17, theglass holding member 16 or the like moves in the vertical direction or any other direction, or even perform rotation in the course of travel. Further, in the cases inFIGS. 10A and 10D , the white reference surface of thereference member 17 is exposed to the inner side of the image reading unit 61 (62), and therefore there is no fear of the white reference surface being damaged or paper powder or dust being deposited on the white reference surface. - Although in the above-described embodiment, the sloping
surface part 19 c is formed on the pushingmember 19 so as to prevent the protrudingportion 18 x of theslide cam 18 from being broken when theapparatus 1 is opened during the reference member reading period, this is not limitative, but in another embodiment, theimage reading apparatus 1 may be configured such that when theapparatus 1 is opened/closed during the reference member reading period, the opening/closing of theapparatus 1 is detected, and thepulse motor 21 is caused to rotate to bring the pushingmember 19 into the state shown inFIG. 5A , thereby preventing breakage of the protrudingportion 18 x. - Detect means for detecting the opening/closing of the
apparatus 1 may be implemented by any type of detector, including a microswitch, a photo-detector switch, and a magnetic detector switch. Alternatively, determination as to the opening/closing of theapparatus 1 may be performed by detecting that the read output from theline image sensor 11 has assumed a value quite different from one in the normal state. It is also possible to use a control means implemented e.g. by the CPU or a combination of the control means and a special-purpose electric circuit as a detect means for detecting the opening/closing of theapparatus 1. - Further, although in the above-described embodiment, the image reading apparatus is capable of double-sided reading of an original D, it is to be understood that the present invention can be applied to an image reading apparatus for single-sided reading.
-
FIG. 11 is a schematic view of an image reading apparatus according to a second embodiment of the present invention. The arrangement of the image reading apparatus inFIG. 11 is illustrated by way of example, and hence this is not limitative. - As shown in
FIG. 11 , theimage reading apparatus 1′ is comprised of apickup roller 2′ that picks up originals D, afeed roller 3′ that feeds the originals D picked up by thepickup roller 2′ into theapparatus 1′, aretard roller 4′ that pairs with thefeed roller 3′ to separate the picked-up originals D one by one, aregistration roller pair 5′ for conveying the originals D while correcting skew of ones conveyed thereto in a skewed state, a pair ofimage reading units 61′ and 62′ that read images on the respective upper and lower surfaces of each of the originals D, conveyroller pairs 7′ that further convey the originals D, and adischarge roller pair 8′ that discharges the originals D out of the apparatus. It should be noted that theimage reading units 61′ and 62′ may be disposed at respective different locations in the original conveying direction instead of being disposed at the same location as shown inFIG. 11 . - The
image reading apparatus 1′ is divided into anupper frame 81′ and alower frame 82′ by a conveying path along which originals D are conveyed. This construction makes it possible to open the conveying path by rotating theupper frame 81′ around apivot shaft 81 a′ manually when jamming of a original D has occurred in theimage reading apparatus 1′ during conveyance thereof, and take out the jammed original from the conveying path. - In the following embodiment, each of the two
image reading units 61′ and 62′ reads images on respective originals conveyed, one by one, by the associated line image sensor in an original reading position. However, the present invention is not limited to the present embodiment insofar as the apparatus is provided with at least one image reading means requiring shading correction. - Further, in the following embodiment, the height of an original discharging position with respect to an original stack position is not particularly limited. For example, the original discharging position may be provided below the original stack position as shown in
FIG. 12 , or alternatively on the opposite side of theimage reading apparatus 1′ from the original stack position as shown inFIG. 13 . Further, although inFIG. 11 , each original is passed between theimage reading units 61′ and 62′ by horizontally moving the original therethrough, theimage reading apparatus 1′ may be configured such that original D is passed between theimage reading units 61′ and 62′ by vertically moving the original D therethrough. -
FIG. 14 is a schematic view of aline image sensor 44 provided in theimage reading unit 62′ appearing inFIG. 11 . - It should be noted that the
image reading unit 61′ is identical in construction to theimage reading unit 62′ except that theimage reading unit 61′ reads not an image on the lower surface of the original D but an image on the upper surface of the same, and hence description thereof is omitted. - As shown in
FIG. 14 , theline image sensor 44 incorporates anLED 442 as a light source, alens array 443, and alight receiving element 441. - In reading an original, the
line image sensor 44 causes reflected light from the original illuminated by theLED 442 to form an image on thelight receiving element 441 by thelens array 443 and converts the image into an electric signal to thereby generate an image reading signal. - Next, a description will be given of the arrangement and configuration of the
image reading unit 62′. -
FIGS. 15A and 15B are cross-sectional views showing theimage reading unit 62′ and its surrounding in this embodiment, in whichFIG. 15A shows a state during the original reading period, andFIG. 15B shows a state during a shading correction data acquisition period. - As shown in
FIGS. 15A and 15B , theimage reading unit 62′ has aframe 42 that has an opening formed on a side thereof along which an original D is conveyed, i.e. an upper side thereof, and pivotally supports apivot shaft 45 of theline image sensor 44 accommodated therein. Theimage reading unit 62′ is further comprised of acontact glass 41 fitted in the opening of theframe 42, for guiding the original D to the original reading location, and awhite reference member 43 for shading correction (hereinafter simply referred to as “the white reference member 43) disposed within theframe 42. This arrangement makes it possible to prevent paper powder and the like dust deposited on an original D conveyed to the upper surface of thecontact glass 41, i.e. the outer side of theframe 42, from contaminating the internal space of theframe 42 and attaching it to thewhite reference member 43. Further, the arrangement makes it possible to carry out a shading correction process, described in detail hereinafter, accurately without necessitating cleaning of thewhite reference member 43. - The
white reference member 43 is disposed such that when theline image sensor 44 is rotated through 900, the reference surface of thewhite reference member 43 faces a reading position of theline image sensor 44. - The
line image sensor 44 is disposed such that the distance from theline image sensor 44 to thewhite reference member 43 during the shading correction data acquisition period (seeFIG. 15B ) becomes equal to an optical distance from theline image sensor 44 to the surface of an original D (i.e. a distance corrected in view of the glass thickness of thecontact glass 15 disposed between theline image sensor 44 and the surface of the original D) in the original image reading period (seeFIG. 15A ). This is to equalize the reading conditions of theline image sensor 44, i.e. the focal position and the amount of illuminating light, between during the original image reading period and during the shading correction data period. - Alternatively, the difference in the amount of reflected light due to the difference in the optical distance may be corrected, instead of disposing the
line image sensor 44 such that the optical distance is equalized as described above. Reading of thereference member 43 can be performed even in a position out of focus, and therefore it is assumed that the reading position includes positions deviated from the position in focus. -
FIG. 16 is a perspective view of theimage reading unit 62′. - As shown in
FIG. 16 , theimage reading unit 62′ has a sensor rotating mechanism comprised of thepivot shaft 45 and amotor 46, and is capable of rotating the reading position of theline image sensor 44 through a desired angle. The sensor rotating mechanism may include a transmission mechanism comprised of gears or the like. Further, themotor 46 may be replaced by a solenoid, a rotary solenoid, or the like actuator. -
FIG. 17 is a flowchart showing the shading correction process executed by the CPU. - As shown in
FIG. 17 , first, when a control means, not shown, detects that a power switch, not shown, of theimage reading apparatus 1′ has been pressed by the user, it turns on the power supply to the electrical sections and components of the apparatus. When the power supply is turned on (YES to a step S701), a motor control section, not shown, drives themotor 46 to rotate theline image sensor 44 into a state for acquisition of shading correction data (step S702). When supplied with a driving current, themotor 46 starts rotation to rotate theline image sensor 44 until the reading position of theline image sensor 44 reaches the position for shading correction data acquisition (step S703). - Then, a sensor control section, not shown, delivers to the line image sensor 44 a control signal for causing the
line image sensor 44 to read the white reference member 43 (step S704). In response to this control signal, theline image sensor 44 starts reading thewhite reference member 43, and generates a reading signal through the reading operation (step S705). The sensor control section converts the reading signal into digital data at an A/D converter section, not shown, to thereby acquire the digital data as shading correction data for each pixel corresponding to each elements of the light receiving element 441 (step S706). The shading correction data may be obtained by performing some computation on the digital data generated through the A/D conversion. - When acquisition of the shading correction data is completed, the motor control section drives the
motor 46 to rotate theline image sensor 44 into a state for reading of an original (step S707). When supplied with a driving current, themotor 46 resumes the rotation to rotate theline image sensor 44 until the reading position of theline image sensor 44 returns to the position for original reading (step S708). - Then, when an instruction for starting original reading is input by the user (YES to a step S709), the sensor control section delivers to the line image sensor 44 a control signal for causing the
line image sensor 44 to sequentially read conveyed originals (step S710). Upon reception of this control signal, theline image sensor 44 starts reading the originals, and sequentially generates reading signals by reading images on the respective originals D (step S711). The sensor control section converts the reading signals into digital data at the A/D converter section, not shown, to thereby acquire the digital data as original image data (step S712). - When acquisition of original image data from entire surface of one original D to be read in response to the reading instruction from the user is completed, shading correction is performed on the original image data based on the acquired shading correction data (step S713), followed by terminating the present process. It should be noted that the shading correction data acquisition process may be started before reading of all the originals to be scanned is completed.
- According to the present process, first, the
line image sensor 44 is rotated until the reading position thereof reaches the position for shading correction data acquisition (step S703), and acquires shading correction data by reading the white reference member 43 (step S706). Thereafter, theline image sensor 44 is rotated until the reading position thereof returns to the position for original reading (step S711), and reads originals D (step S711). This makes it possible to achieve accurate shading correction. - It should be noted, as shown in
FIGS. 18A and 18B, that the sensor rotating mechanism may have apivot shaft 45′ having a pivotal axis thereof positioned apart from the longitudinal axis of theline image sensor 44, in place of thepivot shaft 45 having a pivotal axis thereof positioned close to the longitudinal axis of theline image sensor 44. This makes it possible to swing theline image sensor 44 about thepivot shaft 45′. - As described above, according to the present embodiment, the
line image sensor 44 is configured to perform rotation or swing motion without performing linear motion. This makes the movement range of theline image sensor 44 smaller than that in a case where theline image sensor 44 is configured to perform linear motion, and hence it is possible to reduce the size of theimage reading unit 62′. Further, the pivotal axis exists as fixed points of theline image sensor 44, so that by leading a signal line from an area close to the fixed point, it is possible to prevent occurrence of a trouble due to a disconnection as a problem to be solved when using such an apparatus that has a cable led out from the movable part thereof. -
FIG. 19 is a schematic side view of an image reading apparatus according to a third embodiment of the present invention. It should be noted that the arrangement of the image reading apparatus inFIG. 19 is schematically illustrated by way of example, and hence this is not limitative. - As shown in
FIG. 19 , theimage reading apparatus 1″ is comprised of apickup roller 2″ that picks up originals D, afeed roller 3″ that feeds the originals D picked up by thepickup roller 2″ into theapparatus 1″, aretard roller 4″ that separates the picked-up originals D one by one, aregistration roller pair 5″ provided for conveying the originals D, acontact glass 15″ for guiding each original D to animage reading location 15 a on an original conveying surface thereof, areference member 17″ provided as a white reference in a referencemember reading location 8 b on the original conveying surface of thecontact glass 15″, and aline image sensor 11″ that reads image information on the original D through thecontact glass 15″. Further, theimage reading apparatus 1″ has a conveyroller pair 7″ disposed downstream of theline image sensor 11″. - The
image reading apparatus 1″ is formed by anupper frame 81″ and alower frame 82″, and theline image sensor 11″ is supported in thelower frame 82″ in a manner movable between theimage reading location 15 a and the referencemember reading location 8 b. - With the above-described arrangement, the
image reading apparatus 1″ performs the following operation for reading images on respective original D. First, before starting reading of the originals D, theimage reading apparatus 1″ causes a drive mechanism, not shown, to move theline image sensor 11″ in a direction indicated by an arrow b from a position opposed to theimage reading location 15 a, and reads thereference member 17″ by theline image sensor 11″ through thecontact glass 15″ when theline image sensor 11″ is brought to a position opposed to the referencemember reading location 8 b. A portion of the lower surface of thereference member 17″ corresponding to the referencemember reading location 8 b and the vicinity of the portion provide the reference surface. Shading correction data generated based on an output from theline image sensor 11″ having read thereference member 17″ is stored on a pixel-by-pixel basis. Thereafter, theimage reading apparatus 1″ causes the drive mechanism, not shown, to return theline image sensor 11″ to the home position i.e. theimage reading location 15 a. - After the above-described operation is completed, the
image reading apparatus 1″ takes in the originals D by thepickup roller 2″ and thefeed roller 3″, and separates the originals D, one by one, by theretard roller 4″. While being nipped and conveyed (sub-scanned) by theregistration roller pair 5 and the conveyroller pair 7, each original D has image information on its lower surface read by theline image sensor 11″ in a main scanning direction (i.e. in a direction substantially orthogonal to the original conveying direction). During the image reading operation, image data generated based on an output from theline image sensor 11″ is subjected to shading correction with reference to the aforementioned shading correction data. After image reading is completed, the original D which nipped and conveyed by the conveyroller pair 7″ is discharged out of theapparatus 1″. -
FIG. 20 is a schematic side view of thereference member 17″ appearing inFIG. 19 . - As shown in
FIG. 20 , thereference member 17″ is comprised of awhite film 71 formed on the original conveying surface of thecontact glass 15″ by silk printing (a kind of coating method) and a tape member (adhesive tape) 72 having one adhesive face and affixed to the upper surface of thewhite film 71 so as to prevent thewhite film 71 from being worn by contact with conveyed originals D. - For the
tape member 72, there is used a member which looks white as viewed from the adhesive-face side. When a light source incorporated in theline image sensor 11″ irradiates light onto thewhite film 71 through thecontact glass 15″, thetape member 72 reflects only light having passed through thewhite film 71. This makes thewhite film 71 of thereference member 17″, as viewed through thecontact glass 15″ from the side of theline image sensor 11″, look even whiter, thereby reducing variations in whiteness (variations within the member itself as well as between individual units thereof). As a consequence, the whiteness of thereference member 17″ becomes uniform. - Although in the above-described embodiment, the
white film 71 is formed on the surface of thecontact glass 15″ by silk printing, other methods, such as painting or spray painting (also included in coating method), may be employed to form thewhite film 71 on the surface of thecontact glass 15″. Thecontact glass 15″ may be subjected to surface processing e.g. for roughening the surface of thecontact glass 15″ so as to obtain excellent adhesion of thewhite film 71 to thecontact glass 15″. - Although in the above-described embodiment, the
reference member 17″ is formed by affixing thewhite tape member 72 to thewhite film 71, it suffices that the color of thetape member 72 is substantially white. Further, as shown inFIG. 21 , thereference member 17″ may be formed by affixing asheet form member 74 as a protective member to thewhite film 71 using a double-sidedadhesive tape 73. In this case, when thesheet form member 74 is substantially white, a transparent or white double-sidedadhesive tape 73 is used, and when thesheet form member 74 has a color other than white, a substantially white double-sidedadhesive tape 73 is used. - The
sheet form member 74 may be bonded to thewhite film 71 by an adhesive. In this case, however, it is required to use a substantially whitesheet form member 74 so as to reduce the influence of non-uniform application of the substantially white adhesive. And transparent adhesive also require to use substantially whitesheet form member 74. - The
sheet form member 74 may be formed by a member of sheet metal, such as stainless, so as to suppress wear of thesheet form member 74 due to rubbing with originals. When a sheet metal member having a sufficient thickness is used, the sheet metal member is fixed to a member other than thecontact glass 15″, and hence it is not required to affix or bond thesheet form member 74 to thewhite film 71. In this case, it is more suitable if the lower surface of the sheet metal is machined so as to cause diffuse reflection of light. Further, a substantially white sheet or film may be provided on the lower surface of the sheet metal. Even when a sheet metal is laid on a white film, as mentioned above, and no affixing or bonding to the white film is effected, the combination of the white film and the sheet metal should be considered to be included in the category of thereference member 17″. - The
sheet form member 74 may be fixed by affixing the double-sidedadhesive tape 73 to a portion of thewhite film 71 or thecontact glass 15″ around the vicinity of the referencemember reading location 15 a without affixing the double-sidedadhesive tape 73 to thewhite film 71 in the vicinity of the referencemember reading location 15 a. In this case, the double-sidedadhesive tape 73 can have any color. Further, the protective member, such as the metal plate or the sheet metal member, is not required to cover the whole of thewhite film 71, but it suffices that the protective member covers at least a portion thereof corresponding to reading position of theline image sensor 11″ in the reference member reading position. - Although in the above-described embodiment, the
line image sensor 11″ is movable, theimage reading apparatus 1″ may be configured such that theline image sensor 11″ is fixed and the contact glass is movable, or both can be moved. - Further, the present invention can also be applied to a flat bed scanner provided with an original conveying function.
- Furthermore, the
image reading apparatus 1″ may be configured such that theline image sensor 11″ can move its reading position not by transition or parallel displacement but by performing rotation or other motion. - It is to be understood that the object of the present invention may also be accomplished by supplying a system or an apparatus with a storage medium in which a program code of software, which realizes the functions of either of the above described embodiments is stored, and causing a computer (or CPU or MPU) of the system or apparatus to read out and execute the program code stored in the storage medium.
- In this case, the program code itself read from the storage medium realizes the functions of either of the above described embodiments, and therefore the program code and the storage medium in which the program code is stored constitute the present invention.
- Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, a magnetic-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, a DVD-RW, a DVD+RW, a magnetic tape, a nonvolatile memory card, and a ROM. Alternatively, the program may be downloaded via a network.
- Further, it is to be understood that the functions of either of the above described embodiments may be accomplished not only by executing the program code read out by a computer, but also by causing an OS (operating system) or the like which operates on the computer to perform a part or all of the actual operations based on instructions of the program code.
- Further, it is to be understood that the functions of either of the above described embodiments may be accomplished by writing a program code read out from the storage medium into a memory provided on an expansion board inserted into a computer or a memory provided in an expansion unit connected to the computer and then causing a CPU or the like provided in the expansion board or the expansion unit to perform a part or all of the actual operations based on instructions of the program code.
- While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions.
- This application claims the benefit of Japanese Applications Nos. 2006-79434 filed Mar. 22, 2006, 2006-79437 filed Mar. 22, 2006, and 2006-251041 filed Sep. 15, 2006, which are hereby incorporated by reference herein in their entirety.
Claims (18)
1. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move said image sensor so as to enable said image sensor to read alternatively the original conveyed on the image reading location and said reference member,
wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path.
2. An image reading apparatus according to claim 1 , wherein the reference surface of said reference member is held in close contact with said contact glass.
3. An image reading apparatus according to claim 1 , wherein said reference member is disposed on said glass holding member.
4. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,
wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path, and said reference member is disposed on an original conveying path-side surface of said contact glass.
5. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,
wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path, and said reference member is fixed to an opposite surface of an original conveying path-side surface of said contact glass.
6. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,
wherein said reference member comprises a white coating film formed on an original conveying path-side surface of said contact glass, and a protective member covering at least a portion of said white coating film, for protection of said white coating film.
7. An image reading apparatus configured to read an image formed on an original, comprising:
an image reading unit including a frame that has an opening formed in an original conveying path side thereof, and rotatably supports a pivot shaft of an image sensor housed in said frame, a contact glass disposed on the opening of said frame, configured to guide the original to an image reading location thereon, and a reference member disposed within said frame.
8. An image reading unit provided in an image reading apparatus as claimed in claim 7 .
9. An image reading apparatus for reading an image formed on an original, while conveying the original, comprising:
a contact glass configured to have an original conveying surface on which an original reading position and a reference member reading position exist, and guide the original on the original conveying surface;
an image sensor configured to be capable of moving a reading position thereof between a position opposed to the original reading position and a position opposed to the reference member reading position, and read the image formed on the original through said contact glass guided on the original conveying surface of said contact glass; and
a shading correction reference member as a white reference for said image sensor,
wherein said shading correction reference member comprises a white coating film formed on an original conveying path-side surface of said contact glass, and a protective member covering at least a portion of said white coating film, for protection of said white coating film.
10. An image reading apparatus according to claim 9 , wherein said protective member is a substantially white adhesive tape.
11. An image reading apparatus according to claim 9 , wherein said protective member is substantially white, and wherein said shading correction reference member has a transparent fixing member provided between said protective member and said white coating film, for fixing said protective member to a surface of said white coating film.
12. An image reading apparatus according to claim 9 , wherein said shading correction reference member has a substantially white fixing member provided between said protective member and said white coating film, for fixing said protective member to a surface of said white coating film.
13. An image reading apparatus according to claim 9 , wherein said shading correction reference member has a two-sided adhesive tape for fixing said protective member, in a manner opposed to said white coating film, to at least one of a portion of said white coating film and a portion of said contact glass other than a portion close to said reference member reading location.
14. An image reading apparatus according to claim 11 , wherein said fixing member is a two-sided adhesive tape.
15. An image reading apparatus according to claim 11 , wherein said fixing member is an adhesive.
16. An image reading apparatus according to claim 11 , wherein said protective member is a sheet form member.
17. An image reading apparatus according to claim 11 , wherein said protective member is a sheet metal member.
18. A shading correction reference member disposed at a reference member reading location on a contact glass provided in an image reading apparatus, comprising:
a white coating film formed on an original conveying path-side surface of the contact glass; and
a protective member covering at least a portion of said white coating film, for protection of said white coating film.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US13/163,646 US8164804B2 (en) | 2006-03-22 | 2011-06-17 | Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction |
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JP2006079434A JP2007258959A (en) | 2006-03-22 | 2006-03-22 | Image reading apparatus |
JP2006079437A JP2007258962A (en) | 2006-03-22 | 2006-03-22 | Image reading apparatus and its image reading section |
JP2006-079437 | 2006-03-22 | ||
JP2006-079434 | 2006-03-22 | ||
JP2006-251041 | 2006-09-15 | ||
JP2006251041A JP4922707B2 (en) | 2006-09-15 | 2006-09-15 | Image reading device |
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US13/163,646 Continuation US8164804B2 (en) | 2006-03-22 | 2011-06-17 | Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction |
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US11/689,115 Abandoned US20070223061A1 (en) | 2006-03-22 | 2007-03-21 | Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction |
US13/163,646 Active US8164804B2 (en) | 2006-03-22 | 2011-06-17 | Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction |
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US13/163,646 Active US8164804B2 (en) | 2006-03-22 | 2011-06-17 | Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction |
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Owner name: CANON DENSHI KABUSHIKI KAISHA, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TANAKA, JUN;MACHIDA, TAKASHI;KATO, SHINOBU;AND OTHERS;REEL/FRAME:019255/0005;SIGNING DATES FROM 20070412 TO 20070416 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |