WO1995014259A1 - Apparatus for biasing the curvature of an image carrier on a transfer medium - Google Patents
Apparatus for biasing the curvature of an image carrier on a transfer medium Download PDFInfo
- Publication number
- WO1995014259A1 WO1995014259A1 PCT/US1994/013340 US9413340W WO9514259A1 WO 1995014259 A1 WO1995014259 A1 WO 1995014259A1 US 9413340 W US9413340 W US 9413340W WO 9514259 A1 WO9514259 A1 WO 9514259A1
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- WIPO (PCT)
- Prior art keywords
- paper
- roller
- drum
- nip
- layer
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H5/00—Feeding articles separated from piles; Feeding articles to machines
- B65H5/06—Feeding articles separated from piles; Feeding articles to machines by rollers or balls, e.g. between rollers
- B65H5/062—Feeding articles separated from piles; Feeding articles to machines by rollers or balls, e.g. between rollers between rollers or balls
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
- G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
- G03G15/1695—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer with means for preconditioning the paper base before the transfer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2511/00—Dimensions; Position; Numbers; Identification; Occurrences
- B65H2511/10—Size; Dimensions
- B65H2511/17—Deformation, e.g. stretching
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2515/00—Physical entities not provided for in groups B65H2511/00 or B65H2513/00
- B65H2515/30—Forces; Stresses
- B65H2515/34—Pressure, e.g. fluid pressure
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
- G03G2215/00367—The feeding path segment where particular handling of the copy medium occurs, segments being adjacent and non-overlapping. Each segment is identified by the most downstream point in the segment, so that for instance the segment labelled "Fixing device" is referring to the path between the "Transfer device" and the "Fixing device"
- G03G2215/00409—Transfer device
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
- G03G2215/00535—Stable handling of copy medium
- G03G2215/00687—Handling details
- G03G2215/00704—Curl adding, bending
Definitions
- the present invention pertains in general to electrophotographic print engines, and more particular, to the feeding mechanism for feeding paper to an electrostatic drum or transfer belt.
- the voltage is typically applied at such a level that adherence of the paper to the drum is adequate.
- the voltage is reduced below a certain level, some difficulty exists in adhering the paper to the drum or transfer belt. This is due to the fact that the paper has a tendency to lay flat, whereas the drum or transfer belt has an arcuate surface.
- the paper has been on the drum for a sufficient amount of time, it will conform to the shape of the surface.
- high speed copiers at present do not allow the paper to reside on the drum for very long.
- electrophotographic equipment it is necessary to provide various moving surfaces which are periodically charged to attract toner particles and discharged to allow the toner particles to be transferred.
- the conventional insulating drum technology is one technology that grips the paper for multiple transfers.
- a second method is the semi-conductive belt that passes all the toner to the paper in a single step.
- the third technology is the single transfer to paper multipass charge, expose and development approach.
- the conventional paper drum technology has superior image quality and transfer efficiency.
- hardware complexity eg., paper gripping, multiple coronas, etc.
- media variability and drum resistivity add to the cost and reduce the reliability of the equipment.
- the single transfer paper-to-paper system that utilizes belts has an advantage of simpler hardware and more reliable paper handling.
- it suffers from reduced system efficiency and the attendant problems with belt tracking, belt fatigue and handling difficulties during service.
- it is difficult to implement the belt system to handle multi-pass to paper configuration for improved efficiency and image quality.
- the third technique the single transfer-to-paper system, is operable to build the entire toner image on the photoconductor and then transfer it. This technique offers simple paper handling, but at the cost of complex processes with image quality limitations and the requirement that the photoconductor surface be as large as the largest image.
- the present invention disclosed and claimed herein comprises a paper feed device for feeding paper onto a rotating image carrier.
- a directing device is provided for directing a sheet of paper along a defined path.
- a precurl device then deforms the sheet of paper to have an arcuate deformation.
- a precurl control controls the amount of arcuate deformation imparted to the paper by the precurl device.
- An attachment device then attaches the paper to the image carrier after arcuate deformation thereof by the precurl device.
- the image carrier has a curvature associated therewith that is in the same direction as the arcuate deformation of the paper.
- the precurl device is operable to provide this arcuate deformation tlirough two adjacent rollers having a nip disposed therebetween.
- the nip is disposed along the paper path, with the durometer of the first roller being greater than the durometer of the second roller. This results in the second roller being deformed by the first roller, at least one of the first and second rollers being driven.
- the precurl control is operable to impart a variable pressure to the nip such that the predetermined pressure can be varied. This is done such that the first roller has substantially no deformation associated therewith due to the variable pressure applied to the rollers at the nip.
- FIGURE 1 illustrates a perspective view of the buried electrode drum of the present invention
- FIGURE 2 illustrates a selected cross section of the drum of FIGURE 1;
- FIGURE 3 illustrates the interaction of the photoconductor drum and the buried electrode drum of the present invention
- FIGURE 4 illustrates a cutaway view of the electrodes at the edge of the drum
- FIGURES 5 a and 5b illustrate alternate techniques for electrifying the surface of the drum
- FIGURES 6a-6c illustrate the distributed resistance of the buried electrode drum of the present invention
- FIGURES 7a and 7b illustrate the arrangement of the electrifying rollers to the edge of the drum
- FIGURE 8 illustrates a side view of a multi-pass-to-paper electrophotographic print engine utilizing the buried electrode drum
- FIGURE 9 illustrates a cross section of a single pass-to-paper print engine utilizing the varied electrode drum
- FIGURE 10 illustrates an alternate embodiment of the overall construction of the drum assembly
- FIGURE 11 illustrates another embodiment wherein a resilient layer of the insulating material is disposed over the aluminum core with electrodes disposed on the surface thereof;
- FIGURE 12 illustrates another embodiment of the present invention wherein the core of the drum is covered by an insulating layer with a conducting layer disposed on the upper surface thereof;
- FIGURE 13 illustrates another embodiment of the transfer drum
- FIGURE 14 illustrates another embodiment of the transfer drum construction
- FIGURE 15 illustrates another embodiment of the transfer drum construction
- FIGURE 16 illustrates another embodiment of the transfer drum
- FIGURE 17 illustrates an embodiment illustrating the interdigitated electrodes described above with respect to FIGURE 15;
- FIGURE 18 illustrates a detail of the physical layers in a section of the BED drum with the paper attached thereto;
- FIGURE 19 illustrates a diagrammatic view of the paper layer, the film layer and the uniform electrode layer
- FIGURE 20 illustrates a schematic representation of the paper and film layers
- FIGURE 21 illustrates a schematic diagram of the overall operation of the transfer drum
- FIGURE 22 illustrates a cross sectional diagram of the structure of FIGURE 19, when it passes under a photoconductor drum, which is in a discharge mode;
- FIGURE 23 illustrates another view of the spatial difference between the photoconductor drum and the paper attach electrode disposed about the buried electrode drum;
- FIGURE 24 illustrates a plot of simulated voltage vs. time for an arbitrary section of paper as it travels around the drum 48 four times in a four pass (i.e., color) print;
- FIGURE 25 illustrates a simulated voltage vs. time plot of a single pass
- FIGURE 25a illustrates a graph of decay voltages
- FIGURE 26 illustrates a simulated voltage vs. time plot of a four pass operation
- FIGURE 27 illustrates a simulated voltage vs. time plot of a four pass operation
- FIGURE 27a illustrates an alternate simulated voltage vs. time plot of a four pass operation utilizing Mylar
- FIGURE 28 illustrates a simulated voltage versus time plot for an arbitrary section of paper as it travels around the drum four times during a four pass color print with no discharge before attack;
- FIGURE 29 illustrates the operation of FIGURE 29 with discharge
- FIGURE 30 illustrates a side-view of the overall electrophotographic printer mechanism
- FIGURE 31 illustrates a detail of the pre-curl device
- FIGURE 31a illustrates a detail of the pre-curl operation for the pre-curl rollers
- FIGURES 32a and 32b illustrate devices to measure paper droop and curl
- FIGURE 33 illustrates a view of the pre-curl rollers.
- the buried electrode drum is comprised of an inner core 10 that provides a rigid support structure.
- This inner core 10 is comprised of an aluminum tube core of a thickness of approximately 2 millimeters (mm).
- the next outer layer is comprised of a controlled durometer layer 12 which is approximately 2-3 mms and fabricated from silicon foam or rubber.
- This is covered with an electrode layer 14, comprised of a plurality of longitudinally disposed electrodes 16, the electrodes being disposed a distance of 0.10 inch apart, center line to center line, approximately 0.1 mm.
- a controlled resistivity layer 18 is then disposed over the electrode layer to a thickness of approximately 0.15 mm, which layer is fabricated from carbon filled polymer material.
- FIGURE 2 there is illustrated a more detailed cross-sectional diagram of the buried electrode drum. It can be seen that at the end of the buried electrode drum, the electrodes 16 within electrode layer 14 are disposed a predetermined distance apart. However, the portion of the electrodes 16, proximate to the ends of the drum on either side thereof are "skewed" relative to the longitudinal axis of the drum. As will be described hereinbelow, this is utilized to allow access thereto.
- FIGURE 3 there is illustrated a side view of the buried electrode drum illustrating its relationship with a photoconductor drum 20.
- the photoconductor drum 20 is operable to have an image disposed thereon.
- a latent image is first disposed on the photoconductor drum 20 and then transferred to the surface of the buried electrode drum in an electrostatic manner. Therefore, the appropriate voltage must be present on the surface at the nip between the photoconductor drum 20 and the buried electrode drum. This nip is defined by a reference numeral 22.
- a roller electrode 24 is provided that is operable to contact the upper surface of the buried electrode drum at the outer edge thereof, such that it is in contact with the controlled resistivity layer 18. Since the electrodes 16 are skewed, the portion of the electrode 16 that is proximate to the roller electrode 24 and the portion of the electrode 16 that is proximate to the nip 22 on the longitudinal axis of the photoconductor drum 20 are associated with the same electrode 16, as will be described in more detail hereinbelow.
- the buried electrodes 16 are typically formed by etching a pattern on the outer surface of the controlled durometer layer 12.
- the electrodes 16 are initially formed by disposing a layer of thin, insulative polymer, such as mylar, over the surface of the controlled durometer layer 12.
- An electrode structure is then bonded or deposited on the surface of the mylar layer.
- the electrode pattern is predetermined and disposed in a single sheet on the mylar.
- a layer of insulative material is disposed down and then patterned and etched to form the electrode structure.
- a roller electrode comprising a cylindrical roller 24 that is pivoted on an axle 26.
- a voltage V is disposed through a line 28 to contact the roller 24.
- the roller 24 is disposed on the edge of the buried electrode drum . ,oh that a portion of it contacts the upper surface of the controlled resistivity layer lb and forms a nip 30 therewith.
- a conductive path is formed from the outer surface of the roller electrode 24 through the controlled resistivity layer 18 to electrode 16 in the electrode layer 14. In this manner, a conductive path is formed.
- the electrodes 16 in the electrode layer 14, as will be described hereinbelow, are operable to provide a low conductivity path along the longitudinal axis of the buried electrode drum to evenly distribute the voltage along the longitudinal axis.
- FIGURE 5b illustrates a configuration utilizing a brush 32.
- the brush 32 is connected through the voltage V through a line 34 and has conductive bristles 36 disposed on one surface thereof for contacting the outer surface of the control resistivity layer 18 on the edge of the buried electrode drum.
- the bristles 36 conduct current to the surface of the controlled resistivity layer 18 and therethrough to the electrodes 16 in the electrode layer 14. This operates identical to the system of FIGURE 5 a, in that the electrode 16 in the electrode layer 14 distributes the voltage along the longitudinal axis of the buried electrode drum.
- the buried electrode drum is illustrated in a planar view with the electrode layer "unwrapped" from the controlled durometer layer 12 for simplification purposes.
- the electrode roller 40 is operable to dispose a voltage V on the electrode directly therebeneath, which voltage is conducted along the longitudinal axis of the drum at the portion of the controlled resistivity layer 18 overlying the electrode 16 having the highest voltage thereon. Since the electrode rollers
- the electrode roller 40 disposed at the edge of the buried electrode drum is operable to form a potential at the edge of the buried electrode drum that is reflected along the surface of the buried electrode drum in accordance with the pattern formed by the underlying electrode 16.
- the roller electrode 40 in conjunction with the electrode 16, act as individual activatable charging devices, which devices can be arrayed around the drum merely by providing additional electrode rollers at various potentials, although only one voltage profile is illustrated, many segments could be formed to provide any number of different voltage profiles. Additionally, local extremum voltages occur between electrode strips 16 and overall extremum voltages occur between rollers 40, 42 and 44.
- FIGURE 6b illustrates the potential along the length of the controlled resistivity layer 18. It can be seen that the highest potential is at the electrode 16 underlying the electrode roller 40, since this is the highest potential. Each adjacent electrode 16 has a decreasing potential disposed thereon, with the potential decreasing down to a zero voltage at each of the electrode rollers 42 and 44. The voltage profile shown in FIGURE
- FIGURE 6c illustrates a detailed view of the electrode roller 40 and the resistance associated therewith.
- each of the adjacent electrodes 16 also has a resistance from the surface thereof upward to the upper surface of the controlled resistivity layer 18. Since the resistance along the longitudinal axis of the buried electrode drum with respect to each of the electrodes 16 is minimal, the potential at the surface of the controlled resistivity layer
- each of the electrodes 16 will be substantially the same. It is only necessary for a resistive path to be established between the surface of the roller 40 and each of the electrodes. This current path is then transmitted along the electrode 16 to the upper surface of the controlled resistivity layer 18 in accordance with the pattern formed by buried electrodes 16.
- the buried electrode drum referred to by a reference numeral 48
- the buried electrode drum has two rollers 50 and 52 disposed at the edges thereof and a predetermined distance apart.
- the distance between the rollers 50 and 52 is a portion of the buried electrode drum 48 that contacts the photoconductor drum.
- a voltage V is disposed on each of the rollers 50 and 52 such that the voltage on the surface of the drum 48 is substantially equal over that range.
- a brush 54 is disposed on substantially the remaining portion of the circumference at the edge of the drum 48 such that conductive bristles contact all of the remaining surface at the edge of the drum 48
- the electrode brush 54 is connected through a multiplexed switch 56 to either a voltage
- V on a line 58 or a ground potential on a line 60 The switch 56 is operable to switch between these two lines 58 and 60.
- one mode could be provided wherein the drum 48 was utilized as a transfer drum such that multiple images could be disposed on the drum in a multi-color process.
- the switch 56 selects the ground potential 60 such that when the drum rotates past the electrode roller 52, the voltage is reduced to ground potential at the electrodes 16 that underlie the brush 54.
- FIGURE 7b illustrates the drum 48 and rollers 50 and 52 for disposing the positive voltage therebetween.
- a brush 54 that is disposed around the remaining portion at the edge of the drum 48
- two ground potential electrode rollers 62 and 64 are provided, having a transfer region disposed therebetween. Therefore, an image disposed on the buried electrode drum 48 can be removed from the portion of the line between rollers 62 and 64, since this region is at a ground potential.
- the print engine includes an imaging device 68 that is operable to generate a latent image on the surface of the PC drum 20.
- the PC drum 20 is disposed adjacent the buried electrode drum 48 with the contact thereof provided at the nip 22.
- Supporting brackets [not shown] provide sufficient alignment and pressure to form the nip 22 with the correct pressure and positioning.
- the nip 22 is formed substantially midway between the rollers 50 and 52, which rollers 50 and 52 are disposed at the voltage V.
- a scorotron 70 is provided for charging the surface of the photoconductor drum 20, with three toner modules, 72, 74 and 76 provided for a three-color system, this being conventional.
- Each of the toner modules 72, 74 and 76 are disposed around the periphery of the photoconductor drum 20 and are operable to introduce toner particles to the surface of the photoconductor drum 20 which, when a latent image passes thereby, picks up the toner particles.
- Each of the toner modules 72-76 is movable relative to the surface of the photoconductor drum 20.
- a fourth toner module 78 is provided for allowing black and white operation and also provides a fourth color for four color printing.
- Each of the toner modules 72-78 has a reservoir associated therewith for containing toner.
- a cleaning blade 80 is provided for cleaning excess toner from the surface of the photoconductor drum 20 after transfer thereof to the buried electrode drum 48. In operation, a three color system requires three exposures and three transfers after development of the exposed latent images. Furthermore, the modules 72-76 are connected together as a single module for ease of use.
- the buried electrode drum 48 has two rollers 53 and 54 disposed on either side of a pick up region, which rollers 53 and 54 are disposed at the positive potential V by switch 56 during the transfer operation.
- a cleaning blade 84 and waste container 86 are provided on a cam operated mechanism 88 such that cleaning blade 84 can be moved away from the surface of the buried electrode drum 48 during the initial transfer process.
- paper or similar transfer medium
- the now complete multi-layer image will have been transferred onto the paper on the surface of the buried electrode drum 48.
- the paper is transferred from a supply reservoir 88 through a nip formed by two rollers 90 and 92.
- the paper is then transferred to a feed mechanism 94 and into adjacent contact with the surface of the drum 48 prior to the first transfer step wherein the first layer of the multi-layer image is formed.
- the rollers 53 and 54 are disposed at ground potential and then the paper and multi-layer image are then rotated around to a stripper mechanism 96 between rollers 53 and 54.
- the stripper mechanism 96 is operable to strip the paper from the drum 48, this being a conventional mechanism.
- the stripped paper is then fed to a fuser
- Fuser 100 is operable to fuse the image in between two fuse rollers 102 and 104, one of which is disposed at an elevated temperature for this purpose. After the fusing operation, the paper is feed to the nip of two rollers 106 and 108, for transfer to a holding plate 110, or to the nip between two rollers 112 and 114 to be routed along a paper path 116 to a holding plate 118.
- FIG. 9 there is illustrated a side view of an intermediate transfer print engine.
- the three layers of the image are first disposed on the buried electrode drum 48 and then, after formation thereof, transferred to the paper.
- the surface of the drum is disposed at a positive potential by rollers 50 and 52 in the region between rollers 50 and 52.
- the first exposure is made, toner from one of the toner modules disposed on the latent image and then the latent image transferred to the actual surface of the buried electrode drum 48.
- a third toner is utilized to form a latent image and this image transferred to the drum 48.
- the third layer of the image is formed as a latent image using the second toner, which latent image is then transferred over the previous two images on the drum 48 to form the complete multi-layer image.
- paper is fed from the tray 88 through the nip between rollers 90 and 92 along a paper path 124 between a nip formed by a roller 126 and the drum 48.
- the roller 126 is moved into contact with the drum 48 by a cam operation.
- the paper is moved adjacent to the drum 48 and thereafter into the fuser 100.
- two rollers 130 and 132 are provided on either side of the nip formed between the roller 126 and the drum 48. These two rollers 130 and 132 are operable to be disposed at a positive voltage by multiplexed switches 134 and 136 during the initial image formation procedure.
- rollers 130 and 132 are disposed at a ground voltage with the switches 134 and 136.
- these voltages could be a negative voltage to actually repulse the image from the surface of the drum 48.
- the aluminum support layer 10 comprises the conductive layer in this embodiment, which aluminum core 10 is attached to a voltage supply 140.
- the voltage supply 140 provides the gripping and transfer function, as will be described hereinbelow.
- the voltage supply 140 is applied such that it provides a uniform application of the voltage from the voltage supply 140 to the underside of a resilient layer 142.
- the resilient layer 142 is a conductive resilient layer with a volume resistivity under 10 10 Ohm-cm.
- the layer 142 is fabricated from carbon filled elastomer or material such as butadiene acrylonitrile. The thickness of the layer 142 is
- a controlled resistivity layer 144 which is composed of a thin dielectric layer of material with a thickness of between 50 and 100 microns.
- the layer 144 has a non-linear relationship between the discharge (or relaxation) time and the applied voltage such that, as the voltage increases, the discharge time changes as a function thereof.
- a layer of support material 146 which is typically paper. The photoconductor drum 20 contacts the paper 146.
- a resilient layer 148 of an insulating material comprised of Neoprene is disposed over the aluminum core 10 with electrodes 14 disposed on the surface thereof.
- the electrodes 14 are disposed in a layer, each of the electrodes 14 comprised of an array of conductors separated by a predetermined distance.
- the conductors 14 are covered by a controlled resistivity layer 150, similar to the controlled resistivity layer 144 in FIGURE 10, the gripping layer 150 covered by a controlled resistivity layer with a surface resistivity of between 10 6 -10 10 Ohm/sq.
- the controlled resistivity layer 152 is fabricated from FLEX
- the distance between the electrodes 14 is defined by the following equation:
- v d is the allowable voltage droop between electrodes
- s is the spacing of the electrodes
- r is the sum of the surface resistivity and volume resistance of the layer 150
- w is the overall length of the electrode, which is nominally the width of the drum 10.
- the voltage source 140 is connected to the electrodes 14, as described hereinabove, wherein a conductive brush or roller directly contacts an exposed portion of the electrodes on the edge of the drum or conducts through the upper conductive layers.
- FIGURE 12 there is illustrated another embodiment of the present invention wherein the core of the drum 10 is covered by an insulating layer 154 of a thickness 3mm and of a material utilizing Neoprene, with a conducting layer 156 disposed on the upper surface thereof.
- the conductive layer 156 is connected to the voltage source 140.
- This layer provides the advantage of separating the electrical characteristics of the material from the mechanical characteristics.
- This is covered by an insulative layer 158, similar to the gripping layer 144, with the paper 146 disposed on the upper surface thereof.
- a voltage source 160 is connected to the core 10 and the core 10 then has a conductive resilient layer 162 disposed on the surface thereof.
- the electrodes 14 are disposed in a layer on the upper surface of the layer 162 with the voltage source 164 connected thereto through a conductive brush or such.
- FIGURE 14 there is illustrated another embodiment of the transfer drum construction.
- an insulating core 170 is provided, similar to the dimension of the core 10 but fabricated from insulating material such as polycarbonate.
- the electrode layer with electrodes 14 is then disposed on the surface of the insulating core 170 and the voltage source 140 connected thereto.
- a conducting resilient layer 172 is disposed on the surface of the electrodes 14 to a thickness of 3 mm and fabricated from butylacrylonitrile.
- a gripping layer 174 similar to the gripping layer 144 is disposed on top of the resilient layer 172, with the paper 146 disposed on the upper surface thereof.
- FIGURE 15 there is illustrated another embodiment of the transfer drum construction.
- the conducting layer 156 in FIGURE 11 is removed such that a layer of interdigitated electrodes 176 can be utilized between the gripping layer 152 and the resilient layer 148.
- This resilient layer as described above, is an insulating layer.
- the voltage source 140 is connected to the electrodes 176.
- the interdigitated electrodes increase the value of w in Equation 1, thus allowing a much higher value of r in Equation 1.
- the interdigitated electrodes are illustrated below in FIGURE 17.
- the con 10 has disposed thereon a first resilient layer 180, covered by the electrode layer having electrodes 14 disposed therein.
- the electrodes 14 are connected to a voltage source 140 through conductive brushes or the such.
- a second resilient layer 182 is disposed over the electrodes 14 with the paper 146 disposed on the surface thereof.
- the layer 180 can be a resilient layer that is resistive or insulative.
- the resilient layer 182 is resistive with a resistivity of less than 10 10 Ohms/cm.
- the advantage provided by this configuration is that the physical effects (i.e., nip pressure variations) of the electrode layer are reduced by enclosing the electrodes 14 in two resilient layers 180 and 182.
- interdigitated electrodes each have a plurality of longitudinal arms 184 with extended or interdigitated electrodes 186 and 188 extending from either side thereof Adjacent electrodes will have the interdigitated arms or electrodes 186 and 188 offset along the longitudinal arm 184 such that they will interdigitate with each other, thereby effectively increasing apparent "w" of Equation 1, such that the controlled resistivity layer can be at a higher resistivity to the point that it can be eliminated.
- FIGURE 18 there is illustrated a detail of the physical layers in a section of the BED drum 48 with the paper 146 attached thereto.
- An electrode strip
- the controlled durometer layer 192 represents the resilient layer 142 in FIGURE 10 and subsequent figures.
- the controlled resistivity layer 194 represents the gripping layer 144 in FIGURE 10.
- the controlled durometer layer 192 is disposed between the electrode strip layer 190 and the aluminum drum 10, the electrode strip layer 190 either comprising a plurality of electrodes in strips, as described above, or a single continuous layer.
- FIGURE 19 there is illustrated a diagrammatic view of the paper layer 146, the film layer 194 and the uniform electrode 196 layer, which comprises the electrode strip layer 190.
- a paper attach electrode 198 is provided, which is operable to contact the paper and dispose a potential thereon which, in the preferred embodiment, is ground. At the point the electrode 198 contacts the paper 146, a nip 200 is formed.
- a first capacitor 202 represents a paper layer
- FIGURE 21 there is illustrated a schematic diagram of a simulator circuit capable of simulating the overall operation of the transfer drum 48.
- the schematic representation shows a switch 212 that is labelled K P which is the charge relay, which is operable to connect the upper surface of a paper layer 146, represented by the capacitor 206 and resistor 204, to ground when the switch 212 is closed.
- K P is the charge relay
- attach/transfer voltage source 214 is provided, having the positive voltage terminal thereof connected to the most distal side of resistor 210 and essentially to the uniform electrode layer 197. The other side of the supply 214 is connected to ground.
- a switch 216 is provided which is labelled K F , which is operable to connect the positive side of the supply 214 to the top of the film layer 194. This is a discharge operation that will be described in more detail hereinbelow.
- FIGURE 19 When paper is first presented to the drum in the nip 200 for attachment, the charge distribution of FIGURE 19 is illustrated wherein positive charges are attracted to the upper surface of the paper and negative charges attracted to the lower surface thereof. Similarly, the positive charges are attracted to the upper surface of the film layer 194 and negative charges attracted to the lower surface thereof, with positive charges attracted to the surface of the uniform electrode 196.
- the dielectric layers, layers 146 and 194 most of these charges are just below the surfaces of the respective layers and cannot cross the interface boundary between the film.
- the charges are strongly attracted to each other and provide the attractive force which holds the paper on the drum. This attractive force is normal to the surface of the drum and directly bonds the paper layer 146 to the drum in that direction. Additionally, this normal force is operable for generating the frictional forces that secure the paper to the drum in the remaining two axis, preventing paper slip.
- the source charge for the paper attachment is the attach/ transfer supply 214.
- the switch 212 represents the paper attach electrode 198.
- the composite capacitor formed by the paper and film layers is charged in a manner similar to the charging of C P and C F as illustrated in FIGURE 21 when the relay K P is closed. If the dwell time of a section of paper in the attach nip 200 is sufficiently long relative to the time constant of the resistor 210 (R E ) and the series connected pair capacitor C P and C F , this composite capacitor will charge to a voltage very nearly equal to that of the attach/transfer supply 214. Fully charging the paper film composite capacitor results in the maximum transfer of charge and therefore the generation of the maximum attractive or bonding force of the paper to the drum assembly.
- the capacitance that is associated with the paper and film layers begins to discharge.
- the paper layer then discharges at a rate determined by its dielectric content and volume resistivity, with near complete discharge, i.e., to only a small voltage across the paper, occurring in less than 300 milliseconds.
- the film layer 194 may require more than 200 seconds for near complete discharge, and does so in a manner that is similar to the discharge characteristics of C F and R F in
- FIGURE 4 The larger discharge time of the film layer 94 accounts for the ability of the transfer drum to grip paper much longer than the discharge time of the paper would indicate. Even though the voltage across the paper collapses relatively quickly, the trapped charges that were induced at the paper's surface are trapped at the paper surface by the residual voltage on the film layer. The trapped charges eventually migrate back into the bulk of the paper, but only after the film layer 194 has discharged significantly.
- the operation of the layered structure of FIGURE 18 will be described in more detail as to its effect on the paper gripping operation.
- the resistance of resistor 210 (R E ) is much less than the resistance of the paper R P
- the resistance of resistor 210 (R E ) is much less than resistor R F .
- the composite capacitor will charge to the applied voltage with the time constant R E C EQ , where:
- V CF V A (C P / ( C P + C F ) ) (4 )
- ⁇ F dielectric constant of the film
- Equation 2 Equation 2 can be rewritten as:
- Equation 5 indicate that, during attach, most of the voltage will be developed across the paper, a desirable condition for good gripping.
- V P V A (R P / (R P + RE ) ) (8)
- Equation 8 indicates that, to maximize the voltage across the paper, R E should be selected such that R E is much less than R P . Additionally, it is equally important that C F be selected such that C P is much less than C F .
- Equation 8 shows that very little voltage will be developed across the paper. Thus, only a very small gripping force will be generated.
- toner must then be transferred from the photoconductor to the paper. Since toner transfer efficiency is a function of applied voltage in the transfer nip, it is desirable that the dielectric composed of the paper and film layers have no memory of the attach operation
- FIGURE 22 there is illustrated a cross sectional diagram of the structure of FIGURE 19, when it passes under a photoconductor drum 218 which is in a discharge mode, i.e., there is ground potential applied thereto.
- Toner particles 222 are disposed on the photoconductor drum 218 and have a negative charge placed thereon. This is a conventional transfer operation.
- a transfer nip 220 is formed. Since the electrode layer 196 is a uniform electrode, the voltage of the layer 196 is that of the attach/transfer voltage source 214. This will result in a strong force of attraction at the film and paper interface, represented by a reference numeral 224.
- FIGURE 23 there is illustrated another view of the spatial difference between the photoconductor drum 218 and the paper attach electrode 20 disposed about the buried electrode drum 48. It can be seen that the distance between the paper attach electrode 20 and the photoconductor 218 requires a time T ATT for the paper to move from the paper attach nip 200 to the transfer nip 220. Additionally, the time for the paper to traverse the entire circumference of the drum 48 is the time T REV . Additionally, a discharge roller 201 is provided which is connected to ground for completely discharging the surface.
- FIGURE 24 there is illustrated a simulated voltage versus time plot for an arbitrary section of paper as it travels around the drum 48 four times in a four pass (i.e., color) print.
- the first transition to zero potential is caused by the paper attach electrode 20 contacting the drum and the paper passing into the paper attach nip 200, this represented by the relay 212 (K P ) in FIGURE 21 closing. This is represented by a point 223.
- the paper will then move to the toner transfer nip 220, where the voltage will again go to a zero potential, as represented by a point 225, the time difference between points 223 and 225 being T ATT . This will be a toner transfer point.
- the paper traverses around the drum and the voltage will increase to a higher voltage level (relative to ground potential) at a point 226 after time T REV , at which time the paper will again arrive at the toner transfer nip 220 and the potential will again go to zero as represented by a point 228.
- the paper attach electrode 20 has been removed after the last portion of the paper was attached to the drum 48, in the first pass, this being a single pass. This will continue for three more passes up to a point 230.
- Each of the transitions at the transfer nip 220 are also represented by closure of the relay 214 in the simulation of FIGURE 21.
- the photoconductor drum 218 Because the surface of the photoconductor drum 218 is either discharged or at a low potential (relative to the applied transfer voltage of source 214), the photoconductor drum 218 performs much like the attach electrode 20 in an electrical sense. Although not discussed or shown in detail, the voltage of source 214 is stepped up slightly for each successive toner transfer to account for the thickness of the previous toner layer, this being a conventional operation.
- the surface of the paper is held at a zero potential for the entire time that it is in either the paper attach nip 200 or the transfer nip 220.
- the paper and film composite capacitor (C EQ ) becomes very nearly charged to the full potential of the attach/transfer source 214.
- the capacitance C EQ begins to discharge.
- the first portion of the discharge occurs between points 223 and 225 and is quite rapid, approximately 170 milliseconds, this due primarily to the paper discharging. This is equivalent to the capacitance C P discharging through the resistance R P and is illustrated in more detail in FIGURE 25.
- the voltage on the electrode layer 196 is held at a constant voltage of 1500 volts for the curves of FIGURE 24 and FIGURE 25.
- the voltage available for transfer of toner is the difference between the voltage at the surface of the paper and ground potential, just before the paper enters the transfer nip
- the amount that the film layer discharges between each successive toner transfer pass determines the amount of voltage available for toner transfer.
- the amount of time available for the paper/film discharge after the paper is attached is the time T ATT for the first layer of toner.
- the amount of time available for the paper/film discharge is the time T REV as illustrated in FIGURE 23.
- This time is required for the subsequent layers of toner and, therefore, the voltage across the film layer 194 must not discharge to a level too low to maintain attraction, but it must discharge sufficiently to allow a voltage difference at the transfer nip 220.
- the film layer 194 should have a discharge time constant approximately equal to T ATT to minimize the effect of the residual voltage on the film layer during transfer of the first layer of toner, and yet reserve sufficient potential across the film to maintain gripping of the paper (if R F C F is much less than T ATT , gripping cannot be maintained).
- T ATT T REV 4 and gripping must be maintained for at least as long as T REV .
- the film layer should have a voltage dependant discharge time constant; that is, the RC time constant (or relaxation time constant) of the film should be small for high potentials and large for low potentials.
- a voltage dependent characteristic of this type would allow large potentials to be used for paper attach and toner transfer and allow a small but sufficient residual potential in the film layer for paper gripping maintenance. Because the residual would be small, effects of previous paper attach and toner transfer operations on those subsequent thereto would be minimized.
- V V o * e - ( t/RC) ( 10)
- V is the voltage across a film
- V o is the initial voltage
- R is the resistance of the film.
- the characteristic discharge time is that time that equals the product of RC, and so the exponential term is unity. Specifically the discharge time is given by the equation:
- the behavior of the film discharge time constant is a function of voltage as well as R and C, or more specifically R and/or C are a function of voltage and not constant for the film material. And more specifically, for the improved performance of the gripping layer, the discharge time for the film decreases with increasing voltage:
- V V o * e - ( t/f ⁇ R, C, V) ) ( 12 )
- the exponent is a function that is dependent on V.
- This "nonlinear" behavior is important for the gripping layer to decay sufficient for transfer voltage and yet retain sufficient voltage for gripping. This is shown graphically in the graph of FIGURE 25a. Note that the preferred nonlinear characteristic in the nonlinear decay curve is reflected in quicker initial discharge characteristics for good transfer and then a slowing to a higher value for improved gripping.
- Tables 1 and 2 illustrate discharge characteristics for two films whose dielectric contents are very nearly equal.
- the film associated with Table 1 is an extruded tube of Elf Atochem Kynar Flex 2800, a proprietary copolymer formed using polyvinylidene fluoride (PVDF) and hexafluoropropolene (HFP).
- the average wall thickness was approximately 4 mils.
- the manufacturer's specification for the dielectric for the film is (9.4 - 10.6) ⁇ O .
- the volume resistivity is specified as 2.2 ⁇ 10 14 Ohm-centimeters.
- the film associated with Table 2 was obtained from DuPont as cast 8.5" ⁇ 11 " sheets of Tedlar (TST20SG4), a polyvinyl fluoride (PVF) polymer. The average thickness was approximately 2 mils.
- the manufacture's specifications for the dielectric constant of the film is (8 - 9) ⁇ O .
- the volume resistivity is specified as 1.8 ⁇ 10 14 Ohm-centimeter
- FIGURE 26 illustrates a response for a film such as Mylar, which response illustrates that insufficient voltage is available for subsequent (multiple) passes. Film voltage is held at a constant 2200 volts for each type.
- FIGURE 26 The discharge characteristics of FIGURE 26 are preferred.
- the film of FIGURE 27a the film was manufactured by Apollo as a transparency material. Its chemical and electrical properties are unknown, but the dielectric constant approximates that of Mylar®, approximately 3 ⁇ O . The thickness is approximately 6 mils.
- FIGURE 28 there is illustrated a simulated voltage versus time plot for a sheet of paper as it travels around the drum four times during a four pass color print. The attach and transfer voltage transition shown in the center of the figure are for a single page of a multi-page print job. The voltage available for paper attach or toner transfer is the difference between the voltage at the surface of the paper and ground potential.
- FIGURE 28 it can be noted that the voltage available for paper attach is dependent on the voltage left on the film layer by the previous (and fourth toner layer) transfer. As a result, subsequent pages of a multi-page print job will not be gripped as firmly as the first page. This situation is remedied as illustrated in FIGURE 29 by applying a discharge voltage with the relay 216 labelled K F to the upper surface of the film layer 194. The voltage is approximately 1500 volts in the attach operation in the nip
- FIGURE 30 there is illustrated a side-view of the overall electrophotographic printer mechanism depicting an embodiment of the present invention utilizing a buried electrode drum 48 which utilizes a single electrode or multiple electrodes and the gripping layer described hereinabove with respect to FIGUREs 10, et seq.
- the paper is fed from a paper tray 238 into an inlet paper path 240. Further, it can be routed from a manual exterior paper path 242.
- the paper is then routed between two rollers, a lower roller 244 and an upper roller 246, which provide a "pre-curl" operation, which will be described in more detail hereinbelow.
- the paper is then fed into the nip 200 between the attached electrode roller 198 and the drum 48, as described above.
- a stripper arm 248 is provided that is operable to rotate down about a pivot point 250 onto the surface of the drum 48 to extract or "strip" the paper from the surface of the drum 48, since the paper is electrostatically held to the drum 48.
- the stripper arm 248 is rotated up away from the drum and the attach electrode roller 198 is also pulled away from the drum during the multiple passes.
- a cleaning roller 254 is provided which can be lowered onto the surface of the drum 48 for a cleaning operation after the paper has been stripped therefrom and prior to a new sheet being disposed thereon.
- a brush or roller similar to the roller 40 of FIGURE 6 A is utilized to supply voltage to the electrode layer.
- the rollers 244 and 246, as will be described in more detail hereinbelow, are utilized to place a "pre-curl" on the paper such that it curves upwards about the drum 48. This significantly lowers the voltage required in order to attach the paper with the attach electrode roller 198. If this is not utilized, a significantly higher voltage is required to properly grip paper or the paper will slip. It is necessary for the paper to go around at least one revolution before the paper relaxes onto the drum in the appropriate shape, after which the voltage could be lowered. However, by pre-curling the paper with the rollers 244 and 246, this is alleviated. This pre-curl operation is achieved by using slightly different durometers for the rollers 244 and 246.
- the fuser 100 incorporates two rollers 256 and 258, the roller 258 being the heated roller and the roller 256 being the mating roller to form a nip therebetween.
- the stripper arm 248 strips the paper off of the surface of the drum 248, this paper is routed into the nip between the rollers 258 and 256.
- the durometers of the rollers 258 and 256 are selected such that the roller 256 is softer than the roller 258 and such that the paper will tend to curl around the roller 258, thus providing a "de-curl" to the paper to allow the paper to again flatten out.
- the durometer of the roller 256 is approximately 30 mms and the durometer of the roller 258 is approximately 40 mms.
- the paper is then forwarded to either a transfer path 260 or a transfer path 262.
- the transfer path 260 feeds to the nip between two rollers 264 and 266 for output onto the platform 118.
- toner module 72 is the three color module containing all the required components for development of the color electrostatic latent image on the photoconductor. It is shown as a single inseparable unit to facilitate user handling and is separate from the black module 78, so that the black materials can be handled identically to a black and white only print engine. Furthermore, the color module uses a mechanism to withdraw the developer brush such that the entire unit does not need to be moved, thereby reducing the space and power required to operate the unit.
- a bracket (not shown) is operable to hold a pivot pin 272 about which a pivoting arm 274 pivots.
- the arm 274 has attached to a distal end thereof the attach electrode roller 198, with a protruding portion 276 on the diametrically opposite side of the pin 272 from the electrode roller 198 operable to interface with a cam 278.
- the cam 278 is operable to pivot about a fixed pivot point 280 on the bracket (not shown) to pivot the arm 274.
- the arm 274 is operable to be pivoted into two positions, a first position wherein the attach electrode roller 198 contacts the drum 48, and the second position (shown in phantom line) which pulls the attach electrode roller 198 away from the drum.
- a discharge electrode 284 is pivoted about a pivot pin 286 and has an electrode brush 288 disposed on one end thereof The discharge electrode 284 is operable to pivot in one position such that the electrode brush 288 contacts the surface of the drum 248 to provide a discharge operation prior to the surface of the drum rotating into contact with the nip 200 and, in the second position, to be pivoted away from the surface of the drum
- the protrusion 290 on the rear portion of the electrode 284 is operable to interface with the protrusion 276 on the pivoting arm 274.
- the discharge electrode 284 is spring-loaded (not shown) such that it is biased toward the surface of the drum 48 to contact the drum 48, such that when the pivoting arm 274 pivots to move the protrusion 276 away from the protrusion 290, the electrode brush 288 will pivot into contact with the drum 48.
- the protrusion 276 urges the protrusion 290 up and pivots the electrode 284 and the electrode brush 288 away from the surface of the drum 48.
- the discharge electrode 288 is connected to the same attach/transfer voltage supply, a supply 294, that the buried electrode layer of drum 48 is connected to.
- the paper is fed into a paper path 296, which paper path is comprised of two narrowing flat surfaces that direct the paper.
- the paper is directed to a nip 298 between the rollers 244 and 246.
- the roller 246 pivots about the pivot pin 272 and the roller 242 pivots about a slidable pin 300.
- the pin 300 slides in a slot 302 which is disposed in the bracket (not shown).
- the roller 244 has a durometer that is softer than the durometer of the soft roller 246 such that the paper will tend to roll around the roller 246.
- the size of the rollers 244 and 246 can be selected to determine the amount of pre-curl required.
- the durometers of the two rollers 244 and 246 can also be selected in order to accommodate various thicknesses and weights of paper.
- the durometer of roller 244 is 20 mms
- the roller 246 is a rigid material such as steel.
- a given size relationship between the rollers 244 and 246 and a given durometer relationship therebetween for a set force therebetween will not necessarily insure the appropriate pre-curl. If the attachment voltage on the drum 48 is reduced to as low a level as possible, this pre-curl adjustment may be critical to insure that the paper adequately adheres to the surface of the drum 48 for all weights of paper.
- the roller 244 has a collar 304 disposed on one end thereof that is rotatable with the roller 244 about pivot pin 300 and the collar 304 interacts with a lever 306.
- Lever 306 is pivoted at one end to a fixed pivot pin 308 and, at the other end, rests on the end of a piston 310.
- the piston 310 has a threaded end on the opposite end from the lever 306 which is threadedly engaged with a nut 310 that is secured in the frame.
- An adjustment wheel 312 is disposed about the piston 310 to allow hand adjustment thereof. In this manner, the pin 300 can be reciprocated within the slot 302. It should be noted that the pin 300 is biased downward against the lever by a spring attachment (not shown).
- FIGURE 31 A there is illustrated a detail of the pre-curl operation for the rollers 244 and 246. It can be seen that the paper is pre-curled by the deformation of the roller 244 such that the paper retains a memory of the curling operation. Thus, when the paper is fed to the attach nip 200, the paper will exhibit less of a normal force directed away from the surface of the drum 48.
- a mechanism comprised of a conductive roll is employed to urge the paper against the BED surface.
- a mechanism comprised of a conductive roll is employed to urge the paper against the BED surface.
- FIGURE 32a shows a method to measure the permanent curl or set that occurs in paper after it has been run through the precurling apparatus as shown in FIGURE 33.
- FIGURE 32b shows a method to measure the stiffness (or flexibility) of the paper. In this method, the paper is allowed to droop unsupported over a fixed length and the angle of repose (droop angle) is measured ( ⁇ d ).
- M is the sum of the paper's stiffness ("Droop Angle”, ⁇ d ) and its ability to be curled ("Curl Angle", ⁇ c ):
- k is a constant value determined to "normalize" a standard paper.
- the values Y c , X c , Y d , and X d are determined from measurements taken from the curl and droop experiments.
- Table 3 shows a chart of popular paper types in order of figure of merit. The figure of merit has been normalized to a value of 10 for a widely used paper type in laser printers.
- Tables 4 and 5 illustrate results of curl and droop experiments for the assortment of papers.
- FIGURE 33 illustrates the precurl configuration of a soft roller 300 and hard roller 302 that deflects paper through a subtended angle ⁇ (nip angle).
- Tables 4 and 5 illustrate the result of the precurl function combined with the stiffness of the paper versus the nip angle by radius of curvature quotient for various paper types. It is interesting to note that the some materials show little change as a function of ⁇ /r. This is due to the fact that these materials are observed to be very flexible and require no precurl to grip, (i.e., they are always above the threshold).
- the threshold of curl plus droop may increase to the fourth power of the proportionately to the decrease of the radius of curvature.
- the gripping threshold for a drum radius of 65 millimeters would increase by 34% (or (70/65) 4 ) to 20 degrees (3.3 degrees/mm for the stiffest material tested).
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7514622A JPH10502178A (en) | 1993-11-15 | 1994-11-15 | Apparatus for deflecting the curvature of an image carrier on a transfer medium |
EP95902608A EP0729600B1 (en) | 1993-11-15 | 1994-11-15 | A print engine paper feed device |
DE69424876T DE69424876D1 (en) | 1993-11-15 | 1994-11-15 | DEVICE FOR FEEDING PAPER ON A PRINTING MACHINE |
AU11818/95A AU1181895A (en) | 1993-11-15 | 1994-11-15 | Apparatus for biasing the curvature of an image carrier on a transfer medium |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/152,230 US5398107A (en) | 1992-09-30 | 1993-11-15 | Apparatus for biasing the curvature of an image carrier on a transfer drum |
US08/152,230 | 1993-12-06 | ||
US08/141,273 | 1993-12-06 | ||
US08/147,056 US5442429A (en) | 1992-09-30 | 1993-12-06 | Precuring apparatus and method for reducing voltage required to electrostatically material to an arcuate surface |
US08/147,056 | 1993-12-06 | ||
US08/141,273 US5459560A (en) | 1992-09-30 | 1993-12-06 | Buried electrode drum for an electrophotographic print engine with controlled resistivity layer |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995014259A1 true WO1995014259A1 (en) | 1995-05-26 |
Family
ID=27385626
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1994/013340 WO1995014259A1 (en) | 1993-11-15 | 1994-11-15 | Apparatus for biasing the curvature of an image carrier on a transfer medium |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0729600B1 (en) |
JP (1) | JPH10502178A (en) |
AU (1) | AU1181895A (en) |
DE (1) | DE69424876D1 (en) |
WO (1) | WO1995014259A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4475896A (en) * | 1981-12-02 | 1984-10-09 | Xerox Corporation | Curling/decurling method and mechanism |
US4926358A (en) * | 1987-05-20 | 1990-05-15 | Ricoh Company, Ltd. | System for controlling curls of a paper |
US5176373A (en) * | 1990-09-28 | 1993-01-05 | Sharp Kabushiki Kaisha | Sheet feeding unit incorporating a curl inducing mechanism |
-
1994
- 1994-11-15 DE DE69424876T patent/DE69424876D1/en not_active Expired - Lifetime
- 1994-11-15 AU AU11818/95A patent/AU1181895A/en not_active Abandoned
- 1994-11-15 WO PCT/US1994/013340 patent/WO1995014259A1/en active IP Right Grant
- 1994-11-15 JP JP7514622A patent/JPH10502178A/en active Pending
- 1994-11-15 EP EP95902608A patent/EP0729600B1/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4475896A (en) * | 1981-12-02 | 1984-10-09 | Xerox Corporation | Curling/decurling method and mechanism |
US4926358A (en) * | 1987-05-20 | 1990-05-15 | Ricoh Company, Ltd. | System for controlling curls of a paper |
US5176373A (en) * | 1990-09-28 | 1993-01-05 | Sharp Kabushiki Kaisha | Sheet feeding unit incorporating a curl inducing mechanism |
Non-Patent Citations (1)
Title |
---|
K.J. BUCK & R.A. HAMAKER: "PRE-CURL AND REGISTRATATION STRIPPING DEVICE", XEROX DISCLOSURE JOURNAL, vol. 4, no. 3, May 1979 (1979-05-01), pages 393 * |
Also Published As
Publication number | Publication date |
---|---|
DE69424876D1 (en) | 2000-07-13 |
JPH10502178A (en) | 1998-02-24 |
AU1181895A (en) | 1995-06-06 |
EP0729600B1 (en) | 2000-06-07 |
EP0729600A1 (en) | 1996-09-04 |
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