US3861306A

US3861306A - Combined electrostatic-lithographic duplicating process and apparatus

Info

Publication number: US3861306A
Application number: US453274A
Authority: US
Inventors: Robert Clark Dubois; Jr Philip Pollak; William A Ross
Original assignee: Pitney Bowes Inc
Current assignee: Pitney Bowes Inc
Priority date: 1974-03-21
Filing date: 1974-03-21
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21
Also published as: CA1029790A; JPS50125814A; DE2503149A1; GB1458149A

Abstract

A combined electrostatic-lithographic duplicating process and apparatus is disclosed in which an electrostatic master copy of an original document is made in a zerographic copying unit and the master copy is subsequently converted to a lithographic master from which ink copies are made in a lithograph press. The process is carried out as a continuous operation from the making of the electrostatic master copy through the making of the lithographic ink copies in a series of interrelated steps. Also disclosed is a preferred embodiment of an apparatus for carrying out the above process in which the various instrumentalities for performing the specific steps of the process are so interrelated and arranged that the entire process is carried out by the apparatus disclosed in a continuous operation. The various instrumentalities are modular in construction to facilitate shipping, service and replacement of components.

Description

United States Patent [191 DuBois et al.

[451 Jan. 21, 1975 COMBINED ELECTROSTATIC-LlTHOGRAPHlC DUPLICATING PROCESS AND APPARATUS [75] Inventors: Robert Clark DuBois, Fairfield;

Philip Pollak, Jr., Westport; William A. Ross, Darien, all of Conn.

[52] US. Cl 101/450, l01/132.5, 101/471, 355/17, 355/18 [51] Int. Cl B4lm l/00 [58] Field of Search lO1/l32.5, 450, 451, 463, lO1/471;355/l7, 18,97, 85

[56] References Cited UNITED STATES PATENTS 3,426,678 2/1969 Carper et al 101/450 X 3,648,603 3/1972 Kaminstein 101/l32.5

Primary Examiner-Richard L. Moses Attorney, Agent, or FirmWilliam D. Soltow, Jr.;

Albert A. Scribner; Martin D. Wittstein [57] ABSTRACT A combined electrostatic-lithographic duplicating process and apparatus is disclosed in which an electrostatic master copy of an original document is made in a zerographic copying unit and the master copy is subsequently converted to a lithographic master from which ink copies are made in a lithograph press. The process is carried out as a continuous operation from the making of the electrostatic master copy through the making of the lithographic ink copies in a series of interrelated steps. Also disclosed is a preferred embodiment of an apparatus for carrying out the above process in which the various instrumentalities for performing the specific steps of the process are so interrelated and arranged that the entire process is carried out by the apparatus disclosed in a continuous operation. The various instrumentalities are modular in construction to facilitate shipping, service and replacement of components.

8 Claims, 3 Drawing Figures PATENIEI] JANE] I975 saw 1 or 2 PATENTEB JAN 2 I I975 SHEET 2 [IF 2 COMBINED ELECTROSTATIC-LITIIOGRAPIIIC DUPLICATING PROCESS AND APPARATUS BACKGROUND OF THE INVENTION In the art of grahic reproduction, it has long been well known to make copies of documents by two techniques, lithographic reproduction and electrostatic copying, the former being the older technique. In this technique, a master is prepared by any one ofa number of suitable processes, so that the image areas are oleophilic or ink receptive and the background or nonimage areas are hydrophilic or water receptive to thereby repel ink from the non-image areas. The master is applied to the rotary cylinder or flat bed of a printing press, moistening fluid and ink are applied to the master and copy paper is pressed thereagainst to transfer the ink image from the master to the copy paper. This technique requires that a reverse image be formed on the master. On the other hand, if the image on the master is right reading, the ink image is first transferred from the master to a transfer or blanket roll or plate and from there to the copy paper to provide a right reading image thereon. This technique is known as offset printing and is generally preferred to direct printing for the reason that it produces clearer and sharper copies with less smudging, particularly with fine line images.

In the more recently developed electrostatic technique, a photoconductor consisting of a photoconductive substance coated on an electrically conductive substrate or support has an electrostatic charge uniformly applied to the surface thereof by any suitable means, after which the photoconductor is exposed to illumination in accordance with an image pattern on the document to be copied. The photoconductor then becomes discharged in the light-struck or non-image areas but remains charged in the non-light-struck or image areas so that the thus formed latent electrostatic image will attract and retain electroscopic toner particles applied to the photoconductor by various techniques. The developed visible toner image may either be transferred to plain paper and fixed thereon or it may be retained on the photoconductor and used as such as the final copy if the photoconductive substance is coated on a thin flexible substrate such as paper.

Since it is relatively difficult and expensive to make a lithographic master and to manufacture and operate a lithographic press, it is not economical to utilize the lithographic technique unless an exceedingly large number of copies of the same master are to be made. On the other hand, it is not practical to use the electrostatic technique unless only one or a relatively small number of copies of a document are to be made. Thus, there is a very substantial intermediate duplicating volume need which can be filled by a process and an apparatus according to the present invention in which the electrostatic technique is utilized to make one master Copy of a document and the lithographic technique is utilized to make many ink copies from the master.

These two techniques have been heretofore carried out independently in separate operations and by separate and independent instrumentalities. Thus, it is known to utilize an electrostatic copying machine to make a master which is then manually placed in a lithographic press after having been etched or treated to render the image areas oleophilic and the background areas hydrophilic as discussed above. With the exeption of one machine as disclosed by US. Pat. No. 3,451,336 to Mignone. it is not presently known that a process and apparatus for carrying out the process has been successfully developed for making masters and copies in a continuous, uninterrupted operation. It is, of course, totally unsatisfactory from a practical standpoint to resort to this interrupted process and to require the use of two separate reproducing instrumentalities in an attempt to fullfill the need for intermediate volume duplicating, particularly in an office environment where relatively unskilled personnel are called upon to do the duplicating.

The prior art machine referred to above is the result of an attempt to combine both the electrostatic and lithographic techniques into one continuous process and to provide a unitary machine for carrying out the process. However, the process and apparatus disclosed in the Mignone patent suffer a number ofdisadvantages from a practical standpoint; for one, the original document is illuminated by a scan technique in which the document is fed through the machine, thereby eliminating the possibility of copying from books; for another, the developing of the latent image is accomplished with the use of dry powder toner particles, thereby requiring a fixing or fusing step; for still another, the etching solution is applied by an independent apparatus located between the copier unit and the press unit, thereby necessitating physical handling of the master sheet and instrumentalities not required or utilized in the present invention.

A British Pat. No. 1,215,513 to Kabushiki Kaisha Richo of Japan discloses an improvement on the machine shown in the Mignone patent in that the machine shown in the British patent is capable of copying from books and also discloses the idea of etching the master sheet after it has been applied to the master cylinder of the lithographic press. However, this machine utilizes a moving optics arrangement for scanning a document as distinguished from flash illumination, the former being a slower and requiring additional mechanism and controls to stop the photoconductive sheet while it is being exposed. In addition the Richo patent does not disclose any orienting step or apparatus for properly orienting the master sheet before it is applied to the master cylinder. The present invention eliminates these disadvantages and provides other advantages over the machines disclosed in both of these patents as more fully explained hereinafter.

SUMMARY OF THE INVENTION The present invention is directed generally toward a novel process and apparatus for duplicating and more particularly to a process and apparatus for duplicating through a combination of electrostatic and lithographic techniques which utilizes the best advantages of each technique.

To this end, the process of the present invention comprises basically the steps of providing a flexible master copy sheet having a layer of photoconductive material on an electrically conductive substrate, unifonnly electrostatically charging the master sheet, thereafter exposing the master sheet by subjecting the master sheet to a pattern of illumination corresponding in contrast to the image of indicia on an original document to be copied, thereby leaving a latent electrostatic image of the original document on said master sheet, thereafter moving the master sheet through an orienting zone in which the master sheet is properly aligned, both longitudinally and laterally with respect to the master cylinder of a rotary printing press, after which the master sheet is transferred from the orienting zone to the master cylinder, thereafter applying an etching solution to the master sheet while the latter is held to the master cylinder to render the non-image areas of the master sheet hydrophilic, sequentially applying a moistening fluid and lithographic ink to the master sheet during rotation of the master cylinder, and sequentially feeding copy sheets from a supply thereof to a transfer zone wherein ink deposited on the image areas of the master sheet is transferred to the copy sheets.

In some of the more preferred aspects of the invention, the exposing of the master sheet is carried out by uniformly illuminating the original document from a source of high intensity flash illumination while moving the master sheet through the light pattern reflected from the original document. Also, the development of the latent electrostatic image is accomplished by passing the master sheet through a developing solution of electrostatically attractable toner particles suspended in an insulating carrier solution.

The apparatus of'the present invention comprises the combination, in a single apparatus, of the several electrostatic copying and lithographic duplicating instrumentalities hereinafter fully described which operatively cooperate in the unique and novel manner set forth to accomplish the novel process of this invention.

The apparatus, a significant feature of which is the modular form of construction, comprises generally a first upstanding, generally rectangular frame, a copying apparatus mounted in said frame and having a series of processing instrumentalities in which an image of an original document is produced on a sheet of master copy material, the last in the series of processing instrumentalities being a developing apparatus having means defining an inlet and an outlet through which the sheet of master copy material is fed for development of the image and means for feeding the sheet of master copy material through the series of processing instrumentalities, a second upstanding, generally rectangular frame, a sheet conveying structure mounted in the second frame, the'sheet conveying structure having means defining an inlet end and an outlet end and wherein the orientation of said conveying structure in the second frame is such that the inlet end of the conveying structure is disposed proximate the outlet of said developing apparatus when the first and second frames are connected together, a copy paper storing and feeding apparatus mounted in the second frame which has means for feeding sheets of copy paper seriatim from a supply thereof, a third upstanding, generally rectangular frame, a lithographic press mounted in the third frame, the lithographic press having a series of processing instrumentalities in which an ink image is produced on the sheet of master copy material and is sequentially transferred from the sheet of master copy material to sheets of copy paper which are fed to the lithographic press by the copy paper feeding means, guide means defining a first inlet into the press for receiving a sheet of master copy material from the sheet conveying structure, guide means defining a second inlet into the press for receiving sheets of copy paper from the copy paper feeding apparatus, and wherein the orientation of the lithographic press in the third frame and the orientation of the copy paper feeding apparatus in the second frame are such that the first and second inlets to the lithographic press are disposed proximate the outlet from the conveying structure and the copy paper feeding apparatus respectively when the second and third frames are connected together.

The apparatus is further arranged and constructed to have the developing apparatus of the copying apparatus located within the space defined by the second frame even though the developing apparatus is mounted on the first frame. In addition, the lithographic press includes an orienting device for the master sheets and this is also located within the space defined by the second frame even though it is mounted on the third frame. By this arrangement, considerable saving in space in the overall size of the duplicating machine is achieved.

Having briefly described the background and general nature of the present invention, it is a principal object thereof to provide a process for making multiple copies of an original document utilizing electrostatic and lithographic techniques in a simple and expeditious manner with regard to the advantages of each technique.

It is another object of the present invention to provide a process for making multiple copies of an original document which is carried out in a continuous and uninterrupted manner in which a master copy is first prepared by electrostatically copying an original document onto a sheet of flexible photoconductive material and is then converted into a lithographic master sheet which is utilized to make ink copies.

It is still another object of the present invention to provide an apparatus for carrying out the process of this invention which incorporates into a single apparatus all of the instrumentalities necessary to carry out the process.

Other objects and advantages of the present invention in addition to those mentioned above will be more readily appreciated from an understanding of the details of procedure and structure set forth in the specification hereinafter, with particular reference to the accompanying drawings in which:

FIG. 1 is a longitudinal schematic view of an apparatus for carrying out the process of the present invention and showing the features of the novel apparatus of the invention;

FIG. 2 is an enlarged perspective view of the means for supporting the liquid toner developing unit of the copier component of the machine; and

FIG. 3 is an enlarged perspective view of the sheet conveying structure for transferring master copy sheets from the developing unit to the lithographic press.

DETAILED DESCRlPTlON OF THE INVENTION The process of the present invention commences with the step of providing a sheet of flexible master material comprising a layer of photoconductive material on a conductive substrate, generally called a photoconductor. The master sheet is well known in the art and may comprise any of a variety of substrate materials having the required characteristics of flexibility, strength and electrical conductivity. The photoconductive material may consist of any of a variety of known photoconductive materials of which selenium and zinc oxide are the most typical, although organic photoconductive materials have more recently come into use.

The photoconductive material has the characteristic of being highly electrically insulative in the dark but becoming electrically conductive when exposed to illumination of sufficient intensity.

The next step in the process is to uniformly electro statically charge a sheet of the photoconductor. This may be accomplished by any of a variety of techniques known in the art for depositing a uniform layer of electrostatic charges on the surface of the photoconductive material, most typical of which is by subjecting the photoconductive material to a corona charging device which has a high voltage applied thereto. The polarity of the charge placed on the photoconductive surface will be a function of the type of photoconductive material being utilized, and generally the charging must be carried out in the absence of light while the photoconductive material is in its insulating condition.

The next step in the process is to expose the charged master sheet by subjecting it to a pattern of illumination corresponding in contrast to the image of indicia on an original document to be copied. More particularly, the original document is illuminated by any suitable means in such a way that the light background or non-image areas of the original cause the light to reach the photoconductive material, while the dark image areas of the original prohibit the illumination from reaching the photoconductive material, thereby causing the photoconductive material to become conductive in the light struck non-image areas. This allows the charge residing in these areas to dissipate through the conductive substrate which is generally grounded, thereby leaving a latent electrostatic image of the original document on the master sheet. Several techniques are known for exposing the photoconductor to the pattern of illumination, including the reflex technique shown in the aforementioned Mignone patent as well as the line scan technique in which there is relative motion between the illuminated original and an optical system consisting of a lens and one or more mirrors. These systems are relatively slow and suffer the major drawback that it is impossible to copy from books or any original document other than a flat sheet. In the present invention it is preferred to expose the master sheet by illuminating the original document from a source of high intensity flash illumination while moving the master sheet through the light pattern reflected from the original document. Thus, the document, which may be either a flat sheet or a book, is placed on a suitable transparent support, exposed to a momentary flash of illumination and the master sheet is thereby exposed without the necessity of stopping its movement through the copying instrumentality.

The next step in the process is that of developing the latent electrostatic image by applying electrostatically attractable toner particles to the latent image thereby rendering the image visible. It is possible, however, to use a non-pigmented developing material in which case the developed image is not visible. It is merely a convenience to make the image visible but not a necessity to the process, the only function of the developing material being to provide an oleophilic image area. To accomplish this, it is possible to use either dry powder or liquid toner; the former procedure requires more complex apparatus to apply the powder because of the difficult handling problems involved with this type of developer material. Also, it is necessary to fix the powder to the master sheet, and this requires an additional step and further apparatus for applying the necessary heat and/or pressure. in the present invention, it is preferred to utilize a liquid toning solution containing electrostatically attractable toner particles suspended in an insulating carrier solution, and it is simply a matter of passing the imaged master sheet through a suitable tank containing the developer solution to allow the toner particles to adhere to the latent electrostatic image. The toner particles carry a charge of opposite polarity to the charge on the photoconductive material so that the toner particles are attracted to and adhere to the latent image by electrostatic attraction as is well known in the art. The toner particles remain on the master sheet merely by wiping the excess toner solution from the master sheet as it passes out of the developer tank and drying the master sheet by any suitable means.

After developing, the master sheet is moved through an orienting zone in which the master sheet is mechanically aligned, both longitudinally and laterally, with re spect to the master cylinder of a rotary printing press, after which the master sheet is transferred from the orienting zone to the master cylinder. When it is possible to feed the master sheet directly from a conveyor to the master cylinder, it is considerably more difficult to obtain proper registration of the master sheet on the cylinder by this technique; it has been found that mechanically orienting the master sheet increases the reliability of proper loading of the master sheet on the cylinder and permits loading at higher speeds thereby increasing the overall speed of the duplicating process. This result will be more clearly apparent after consideration of the description hereinbelow of the instrumentality by which this is accomplished.

After the master sheet is transferred to the master cylinder, an etching solution is applied to the master sheet while it is held to the master cylinder. The purpose of the etching solution is to render the non-image areas of the master sheet hydrophilic while the toner image remains oleophilic. The specific chemistry by which this change occurs need not be explained in detail herein since it forms no part of the present invention and is well known in the art. It is sufficient for the purpose of this invention to understand that the photoconductive material and the toner particles used to develop the latent image are both normally oleophilic in nature, that is, they will accept oil base substances but repel water base substances. The lithographic ink used in the press is an oil base ink and therefore will be accepted by the toner particle image when applied to the master sheet in the press. However, it is necessary to convert the background areas of the master sheet from oleophilic to hydrophilic so that these areas will be water receptive and ink repellant. This is accomplished by the etching solution which chemically converts the photoconductive material in the background areas to a hydrophilic material, the toner image being resistant to the etching solution.

After the master sheet has been etched as above described, a moistening fluid and lithographic ink are sequentially applied to the master sheet during each revolution of the master cylinder. The moistening solution moistens the background areas of the master sheet which have been made hydrophilic so that these areas in the presence of moistening fluid will not accept any ink. The image areas on the other hand, accept the ink which is applied to the master sheet after the moistening fluid is applied thereto.

The final step in the process is to transfer the ink image from the master sheet to a sheet of copy paper. This may be accomplished either by direct transfer in which the ink is transferred directly from the master sheet to the copy paper by bringing the copy into direct pressure contact with the master sheet; or by offset transfer in which the ink image is transferred first from the master sheet to an intermediate transfer or blanket roll and then from this roll to the copy sheet which is brought into pressure contact with the transfer roll. The particular mode of transfer selected determines whether a right reading or reverse image is placed on the master in the master sheet imaging step. If direct ink transfer is used, the image on the master must be a reverse image of the indica on the original document so that a right reading ink image will be reproduced on the copy sheets. On the other hand, if the offset transfer mode is used, the image on the master sheet must be right reading since the ink image transferred to the blanket roll will be reversed in this transfer step and will be reversed again when the ink image is transferred from the blanket roll to the copy sheets so as to appear right reading thereon. The orientation of the image on the master sheet is controlled merely by appropriate selection of the number of mirrors in the optical path as is well known in the art. In the present invention, a right reading image is projected onto the master sheet since it is preferred to use the offset mode of transfer of the ink image from the master sheet to the copy sheets in view of the well recognized advantages of this type of transfer over direct transfer.

The duplicating apparatus of the present invention will now be described in relation to the above described duplicating process as well as to the novel features of construction embodied in the apparatus. The apparatus 10 comprises a first upstanding generally rectangular frame 12 conveniently supported by casters 14 which serve to make the frame and the structure supported thereby portable. The first frame supports a copying apparatus generally designated by the numeral 15 and comprising atransparent support member 16 on which a document is placed for copying. A plurality of high intensity flash lamps 18 are disposed usually adjacent the four corners of the document support member 16 to illuminate the entire document support member when they are energized. A suitable lens 20 is supported by a box-like structure 22 which confines the light from the lamps 18 to the vicinity of the document support member. The lens 20 focuses the rays of light reflected from the document and from a mirror 24 onto an image plane 26 so that the full image of the document is projected onto the image plane 26.

A pair of supply rolls 28 of master material are conveniently mounted in the frame 12. Each roll 28 has associated therewith a pair of intermittently, driven feed rollers 30, a cut-off device 32 for severing sheets of master material from the rolls 28 and continuously driven feed rollers 34 for conveying a severed sheet of master material into a common feed path which commences with a pair of feed rollers 36. Suitable sheet guide plates are provided for'directing the lead edge of the master material through the structure thus far described which guide plates are well known in the art and need not be further described.

The master material is any suitable, photoconductor which comprises a photoconductive material such as zinc oxide coated on an electrically conductive substrate such as paper. A sheet of photoconductor is fed through a suitable charging device such as the corona charger 38 in which the photoconductor receives a uniform electrostatic charge. The sheet is fed by feed rollers 40 past a curved guide plate 42 where further movement of the sheet is taken over by a vacuum conveyor 44 which moves the sheet across the image plane 26. When the sheet of master material is properly centered in the image plane 26, the flash lamps 18 are energized and the master copy sheet is thereby exposed to a pattern of light corresponding in contrast to the image of indicia on the original document. As is well known in the electrophotographic copying technique. the charge is dissipated in the non-image areas thereby leaving a latent electrostatic image on the master sheet. The intensity of the illumination from the flash lamps 18 is sufficiently high and of sufficiently short duration that the sheet of master material can be exposed in the manner described while it is being moved by the vacuum conveyor 44. V

The vacuum conveyor 44 feeds the master sheet to a pair of feed rollers 46 which assure proper withdrawal of the master sheet from the vacuum conveyor 44. A second pair of feed rollers 48 feed the sheet into a substantially U-shaped guide 50 which directs the master sheet into a developing apparatus generally designated by the numeral 52. The specific construction of the developing apparatus is not critical to the present invention and may be any well known form of liquid toner applying device. Generally, the device comprises a tank 54 for holding a supply of liquid toner and a guide means 56 defining an inlet 58 and an outlet 60, the outlet 60 being closely adjacent a pair of squeegee rollers 62 for wiping off excess liqiud as the master sheet passes therebetween. The developing device also includes a rotating cylinder 64 which assists in guiding the master sheet through the developing apparatus. Generally, the master sheet is either passed through a pool of toner solution or the solution is pumped through a manifold and sprayed onto the surface of the photoconductive material.

As clearly seen in FIG. 1, the entire developing apparatus 52 is located within the space defined by a second upstanding, generally rectangular frame 66 which is also supported by casters 68 for mobility. As best seen in FIG. 2, the first frame 12 is provided with a bracket 70 which is bolted to an upright leg of the frame 12 as by the bolt 71. The bracket 70 has a portion 70a which extends inwardly of the machine and another portion 70b which extends toward the copier components contained within the frame 12. As best seen in FIG. 1, the bracket 70 is essentially U-shaped and extends upwardly to a higher location where it is again connected to the upright leg of the frame 66. A second identical bracket is similarly mounted on the opposite side of the machine. The brackets 70 may be connected by crossmembers (not shown) if desired for the purpose of stability or strength. Each bracket 70 has connected thereto an upstanding elongate support plate 73 as by the bolts 74, the support plates being connected at both upper and lower portions of the brackets 70. Each support plate 73 has supporting extensions 75 located at an intermediate point along the support plates and at the upper end thereof (note FIG. 1) and which extend inwardly of the space defined by the frame 66. The developing apparatus 52 includes any suitable form of frame which can be bolted or otherwise secured to the upper supporting extensions 75 of the plates 73. An elevating mechanism 77 rests upon a plate 79 which extends between the lower supporting extensions 75 so that the toner tank 54 can be raised or lowered for service of the tank. By this construction, the developing apparatus remains an integral portion of the copying component of the overall duplicating machine while actually occupying otherwise unused space within the second frame 66.

Referring back to FIG. 1, the second frame 66 above mentioned is removably secured to the first frame 12 by any suitable means such as latches or bolts 76; locating pins and holes as is well known in the art may also be provided if desired. A master sheet conveying structure, generally designated by the numeral 85, is mounted on the frame 66 by means of brackets 67 (FIG. 3) connected to a horizontal portion of the frame 66, the brackets 67 supporting a shaft 69 on which the side plates 81 of the conveying structure are pivotally mounted. The side plates are held in the position shown by latch assemblies 83. The sheet conveying structure 85 comprises a pair of juxtaposed perforated guide plates 78 between which the master sheet is fed by the sequeegee rollers 62 and a plurality of blotting feed rollers 80, these rollers being covered with any suitable absorbent material to partially dry the master sheet. A flared mouth 82 formed on the guide plates 78 defines an inlet into the sheet conveying structure, and another pair of feed rollers 87 defines an outlet from the sheet conveying structure. A plurality of fans 84 are conveniently mounted on opposite sides of the sheet conveying structure to direct air onto the master sheet passing between the perforated guides 78 in order to assure further drying of the master sheet. It will now be seen that the orientation of the sheet conveying structure in the second frame is such that the inlet 82 of the conveying structure is disposed proximate the outlet 60 of the developing apparatus when the first and second frames are connected together so that the master sheet moves directly from the developing apparatus into the conveying structure. I

The second frame 66 also includes the copy paper storing and feeding mechanism for the lithographic press. Thus, the frame 66 suitably supports a generally vertically oriented frame 86 which defines rails on opposite sides of the machine along which a paper supporting platform 88 rides when operated upon by a pulley system built into the frame 86 and driven by an electric motor 90. The specific details of this structure form no part of the present invention, and it is sufficient to a full understanding of the invention to understand that as sheets of copy paper are fed seriatim from the top of the stack of copy, the motor 90 drives the pulley system slowly to intermittently raise the paper support 88 so that the top of the stack is always substantially at the same height.

The individual sheets of copy paper are fed from the top of the stack 92 by a conventional pneumatic sheet separator mechanism 94 which lifts the top most sheet from the stack and advances the lead edge of the sheet into the nip of a pair of feed rollers 95 which advance the sheet toward the impression cylinder of the lithographic press yet to be described. Again it should be noted that the particular details of construction of the sheet separating and feeding mechanism form no part of the present invention, and any suitable mechanism which will accomplish the desired purpose may be used.

A third upstanding, generally rectangular frame 96 is provided, and is also mounted on casters 98 for mobility. The frame 96 is removably connected to the frame 66 in the same manner as the latter is connected to the frame 12, this is by any suitable combination of latches, bolts etc., preferably with locating pins and holes. One such connecting bolt is shown as at 100. The frame 96 contains the lithographic press component of the duplicating machine which can be any form of rotary direct or offset lithographic press modified as described hereinbelow to cooperate with the master sheet and copy paper feeding components described above.

The lithographic press shown in FIG. 1 is of the offset type and comprises a master cylinder 102 to which master sheets are transferred from the sheet conveyor structure by an orienter device which will be more fully described below. Positioned around the master cylinder 102 is an etching solution applicator 104 which applies etching solution to the master sheet by means of a movable applicator roller during the first few revolutions of the master cylinder after the sheet is secured thereon. The etching solution converts the background areas of the master from oleophilic to hydrophilic so that these areas will readily accept dampening fluid and will not accept ink. The image areas on the master sheet will accept ink due to the fact that the toner particles in the developing solution are oleophilic by nature. The chemistry of this operation is well known in the lithographic art.

A water or dampening fluid unit 108 is disposed adjacent the master cylinder and includes an applicator roller 110 which applies a properly regulated amount of dampening solution to the master sheet during rotation of the master cylinder after the application of the etching solution has been completed. The dampening fluid unit 108 remains in operation during the time that lithographic copies are being produced.

An inking unit 112 is also disposed adjacent the master cylinder and includes a pair of applicator rollers 114 which apply a properly regulated supply of ink to the master sheet during rotation of the master cylinder after the application of the etching solution has been completed.

A blanket cylinder 116 is mounted for rotation to have its peripheral surface in contact with the surface of the master cylinder so that during rotation of these cylinders the ink image formed on the master sheet is transferred to the blanket cylinder. An impression cylinder 118 is mounted for rotation in position to receive sheets of copy paper from the copy paper feeding mechanism and to have its peripheral surface in contact with the peripheral surface of the blanket cylinder so that the ink image on the blanket cylinder is transferred to the copy paper as the sheet of paper passes through the nip of the blanket and impression cylinders. Finally, a delivery cylinder 120 is positioned adjacent the impression cylinder and operates to take the printed copy sheet from the impression cylinder and transfer it to a delivery chute 122, which in turn deposits the copies into a collection tray 124 for retrieval by an operator.

It should be understood that all of the structure described above commencing with the master cylinder 102 is mounted between a pair of upstanding supporting plates one of which is designated in phantom lines by the numeral 125. These plates are provided with appropriate bearings and brackets, as the case may be, which are required to support the above described components. The upstanding supporting plates are mounted in the third frame 96 in any convenient manner, and the specific construction of the plates and the manner in which they are mounted in the frame 96 are not significant to the present invention except as hereinafter described.

Referring to FIG. 1, the upper portion of the plates designated as 126 are provided with lateral extensions 130 which extend away from the frame 96 on the side thereof normally adjacent the frame 66 so that when the two frames are connected, the extensions 130 project into the space defined by the frame 66 and overlie a portion of the copy paper storage and feeding mechanism. The extensions 130 removably support a master sheet orienting device which is shown schematically in FIG. 1 and indicated by the numeral 134. The master sheet orienting device is fully disclosed and claimed in a separate copending U.S. Pat. application Ser. No. 413,836 filed on Nov. 8, 1973 by the assignee of this application and only so much of the orienting device as is hereinbelow described is pertinent to the present invention. The function of the orienting device is to receive master sheets from the sheet conveyor and to shift the sheet laterally and/or longitudinally of its direction of travel in order to properly orient the sheet with respect to a transfer mechanism, which is part of the lithographic press and functions to transfer the master sheet from the orienting device 134 to the master cylinder 102.

The orienting device 134 has an infeed end 136 which is positioned to receive master sheets from the discharge end 87 of the sheet conveyor. The infeed end 136 defines in effect a guide means defining an inlet into the lithographic press for receiving master sheets from the sheet conveying structure 85, since the orienting device is effectively a part of the press component. The orienting device has an outlet end 138 which is disposed adjacent the gripping fingers 140 of the aforementioned transfer mechanism. The gripper fingers 140 open in a manner well known in the art and grasp the lead edge of the master sheet and then swing in an arc to bring the lead edge of the master sheet into contact with grippers fingers 142 which are mounted on the master cylinder. Again, in a well known manner in the press art, the lead edge of the master sheet is transferred from the transfer grippers 140 to the master cylinder grippers 142 and is thereafter rotated with the master cylinder 102 for making ink copies in the manner described above.

A pair of

guide plates

143 and 145 are also suitably mounted on the press frame 126 and form a guide means defining an inlet into the lithographic press for receiving sheets of copy paper from the feed rollers 95 of the copy paper feeding apparatus 94. It will be apparent from the foregoing that the orientation of the lithographic press in the frame 96 and the orientation of the conveying structure 85 and the copy paper feeding apparatus 94 in the frame 66 are all such that the inlet 136 of the orienting device 134 and the inlet defined by the

guide plates

143 and 145 to the press are disposed proximate the outlet 87 from the sheet conveying structure 85 and the outlet 95 from the copy paper feeding apparatus respectively when the frame 66 and the frame 96 are connected together.

When the required member of copies have been made, the master cylinder grippers 142 release the master sheet, and the lead edge of the master sheet is directed into a conveyor guide 144 and transported by

feed rollers

146 and 148 to a collection tray 150 which serves to store the used master sheets until they are removed and discarded.

What is claimed is:

1. A method of making multiple lithographic copies of an original document comprising the steps of:

A. providing a sheet of flexible master material comprising a layer of photoconductive material on a conductive substrate.

B. uniformly electrostatically charging the master sheet,

C. thereafter exposing the master sheet by subjecting the master sheet to a pattern of illumination corresponding in contrast to the image of indicia on an original document to be copied, thereby leaving a latent electrostatic image of the original document on said master sheet,

D. thereafter developing the latent electrostatic image by applying electrostatically attractable toner particles to the latent image on said master sheet,

E. thereafter moving the master sheet through an orienting zone in which the master sheet is properly aligned, both longitudinally and laterally, with respect to the master cylinder of a rotary printing press, after which the master sheet is transferred from the orienting zone to the master cylinder,

F. thereafter applying an etching solution to the master sheet while the latter is held to the master cylinder to render the non-image areas of the master sheet hydrophilic,

G. sequentially applying a moistening fluid and lithographic ink to the master sheet during rotation of the master cylinder, and

H. sequentially feeding copy sheets from a supply thereof to a transfer zone wherein ink deposited on the image areas of the master sheet is transferred to the copy sheet.

2. The method of claim I wherein the exposing of the master sheet is accomplished by non-uniform illuminating the original document from a source of high intensity flash illumination while moving the master sheet through the light pattern reflected from the original document.

3. The method of claim 1 wherein the developing of the latent electrostatic image is accomplished by passing the master sheet through a developing solution of electrostatically attractable toner particles suspended in an insulating carrier liquid.

4. A method of making multiple lithographic copies of an original document comprising the steps of:

A. providing a flexible master copy sheet having a layer of photoconductive material on a conductive substrate,

B. uniformly electrostatically charging the master sheet,

C. thereafter exposing the master sheet by illuminating the original document from a source of high intensity flash illumination while moving the master sheet through the light pattern reflected from the original document, thereby leaving a right reading latent electrostatic image of the original document on said master sheet.

D. thereafter developing the latent electrostatic image by passing the master sheet through a developing solution of electrostatically attractable toner particles suspended in an insulating carrier liquid, E. thereafter moving the master sheet through an orienting zone in which the master sheet is properly aligned, both longitudinally and laterally, with respect to the master cylinder of an offset printing press, after which the master sheet is transferred from the orienting zone to the master cylinder, F. thereafter applying an etching solution to the master sheet while the latter is held to the master cylinder to render the non-image areas of the master sheet hydrophilic and the image areas oleophilic, G. sequentially applying a moistening fluid and lithographic ink to the master sheet during rotation of the master cylinder and transferring reverse reading images to a blanket roll, and H. sequentially feeding copy sheets from a supply thereof between the blanket roll and an impression cylinder to transfer the reverse ink images from the blanket roll to the copy sheets. 5. A duplicating apparatus comprising: A. a first upstanding, generally rectangular frame, B. a copying apparatus mounted in said first frame,

said copying apparatus having 1. a series of processing instrumentalities in which an image of an original document is produced on a sheet of master material, the last in said series of processing instrumentalities, being a developing apparatus having means defining an inlet and an outlet and through which the sheet of master material is fed for development of the image, and

2. means for feeding the sheet of master material through said series of processing instrumentalities,

C. a second upstanding, generally rectangular frame,

D. a sheet conveying structure mounted in said second frame, said conveying structure having means defining an inlet end and an outlet end and wherein the orientation of said conveying structure in said second frame is such that said inlet end of said conveying structure is disposed proximate said outlet of said developing apparatus when said first and second frames are connected together,

E. a copy paper storing and feeding apparatus mounted in said second frame, said apparatus having means for feeding sheets of copy paper seriatim from a supply thereof,

F. a third upstanding, generally rectangular frame,

G. a lithographic press mounted in said third frame,

said lithographic press having 1. a series of processing instrumentalities in which an ink image is produced on the sheet of master copy material and is sequentially transferred from the sheet of master copy material to sheets of copy paper which are fed to said lithographic press by said copy paper feeding means,

2. guide means defining a first inlet into said press for receiving the sheet of master material from said sheet conveying structure,

3. guide means defining a second inlet into said press for receiving the sheets of copy paper from said copy paper feeding apparatus,

and wherein the orientation of said lithographic press in said third frame and the orientation of said conveying structure and said copy paper feeding apparatus in said second frame are such that said first and second inlets to said lithographic press are disposed proximate said outlet from said conveying structure and said copy paper feeding apparatus respectively when said second and third frames are connected together.

6. A duplicating apparatus as set forth in claim 5, wherein said first, second and third frames include means for removably connecting said frames to each other.

7. A duplicating apparatus as set forth in claim 5, wherein said first frame includes bracket means secured to said first frame, said bracket means including supporting members extending from said first frame into the space defined by said second frame, said developing unit being mounted on said supporting members whereby said developing unit is supported in said space defined by said second frame when said first and second frames are connected together.

8. An apparatus as set forth in claim 5, wherein said lithographic press includes a pair of support plates mounted in said third frame on which said processing instrumentalities are mounted, said plates having lateral extensions located adjacent the upper end of said support plates and which extend into the space defined by said second frame when said second and third frames are connected together, and wherein said guide means defining said first inlet into said press for receiving master material is mounted on said extensions of said support plates so as to overlie said copy paper storing and feeding apparatus mounted in said second frame.

Claims

1. A METHOD OF MAKING MULTIPLE LITHOGRAPHIC COPIES OF AN ORIGINAL DOCUMENT COMPRISING THE STEPS OF: A. PROVIDING A SHEET OF FLEXIBLE MASTER MATERIAL COMPRISING A LAYER OF PHOTOCONDUCTIVE MATERIAL ON A CONDUCTIVE SUBSTRATE, B. UNIFORMLY ELECTROSTATICALLY CHARGING THE MASTER SHEET, C. THEREAFTER EXPOSING THE MASTER SHEET BY SUBJECTING THE MASTER SHEET TO PATTERN OF ILLUNINATION CORRESPONDING IN CONTRAST TO THE IMAGE OF INDICIA ON AN ORIGINAL DOCUMENT TO BE COPIED, THEREBY LEAVING A LATENT ELECTROSTATIC IMAGE OF THE ORIGINAL DOCUMENT ON SAID MASTER SHEET, D. THEREAFTER DEVELOPING THE LATENT ELECTROSTATIC IMAGE BY APPLYING ELECTROSTATICALLY ATTRACTABLE TONER PARTICLES TO THE LANTENT IMAGE ON SAID MASTER SHEET, E. THEREAFTER MOVING THE MASTER SHEET THROUGH AN ORIENTING ZONE IN WHICH THE MASTER SHEET IS PROPERLY ALIGNED , BOTH LONGITUDINALLY AND LATERALLY, WITH REPECT TO THE MASTER CYLINDER OF A ROTARY PRINTING PRESS, AFTER WHICH THE MASTER SHEET IS TRANSFERRED FROM THE ORIENTING ZONE TO THE MASTER CYLINDER, F. THEREAFTER APPLYING AN ETCHING SOLUTION TO THE MASTER SHEET WHILE THE LATTER IS HELD TO THE MASTER CYLINDER TO RENDER THE NON-IMAGE AREAS OF THE MASTER SHEET HYDROPHILIC, G. SEQUENTIALLY APPALYING A MOISETEING FLUID AND LITHOGRAPHIC INK TO THE MASTER SHEET DURING ROTATION OF THE MASTER CYLINDER, AND H. SEQUENTLY FEEDING COPY SHEETS FROM A SUPPLY THEREOF TO A TRANSFER ZONE WHEREIN INK DEPOSITED ON THE IMAGE AREAS OF A MASTER SHEET IS TRANSFERRED TO THE COPY SHEET.

2. The method of claim 1 wherein the exposing of the master sheet is accomplished by non-uniform illuminating the original document from a source of high intensity flash illumination while moving the master sheet through the light pattern reflected from the original document.

2. means for feeding the sheet of master material through said series of processing instrumentalities, C. a second upstanding, generally rectangular frame, D. a sheet conveying structure mounted in said second frame, said conveying structure having means defining an inlet end and an outlet end and wherein the orientation of said conveying structure in said second frame is such that said inlet end of said conveying structure is disposed proximate said outlet of said developing apparatus when said first and second frames are connected together, E. a copy paper storing and feeding apparatus mounted in said second frame, said apparatus having means for feeding sheets of copy paper seriatim from a supply thereof, F. a third upstanding, generally rectangular frame, G. a lithographic press mounted in said third frame, said lithographic press having

3. guide means defining a second inlet into said press for receiving the sheets of copy paper from said copy paper feeding apparatus, and wherein the orientation of said lithographic press in said third frame and the orientation of said conveying structure and said copy paper feeding apparatus in said second frame are such that said first and second inlets to said lithographic press are disposed proximate said outlet from said conveying structure and said copy paper feeding apparatus respectively when said second and third frames are connected together.

4. A method of making multiple lithographic copies of an original document comprising the steps of: A. providing a flexible master copy sheet having a layer of photoconductive material on a conductive substrate, B. uniformly electrostatically charging the master sheet, C. thereafter exposing the master sheet by illuminating the original document from a source of high intensity flash illumination while moving the master sheet through the light pattern reflected from the original document, thereby leaving a right reading latent electrostatic image of the original document on said master sheet, D. thereafter developing the latent electrostatic image by passing the master sheet through a developing solution of electrostatically attractable toner particles suspended in an insulating carrier liquid, E. thereafter moving the master sheet through an orienting zone in which the master sheet is properly aligned, both longitudinally and laterally, with respect to the master cylinder of an offset printing press, after which the master sheet is transferred from the orienting zone to the master cylinder, F. thereafter applying an etching solution to the master sheet while the latter is held to the master cylinder to render the non-image areas of the master sheet hydrophilic and the image areas oleophilic, G. sequentially applying a moistening fluid and lithographic ink to the master sheet during rotation of the master cylinder and transferring reverse reading images to a blanket roll, and H. sequentially feeding copy sheets from a supply thereof between the blanket roll and an impression cylinder to transfer the reveRse ink images from the blanket roll to the copy sheets.

5. A duplicating apparatus comprising: A. a first upstanding, generally rectangular frame, B. a copying apparatus mounted in said first frame, said copying apparatus having