GB2272866A - Non-photographic production of planographic printing plates. - Google Patents

Abstract

A hydrophilic surface is imaged by writing (eg using an ink-jet printer) with a photocurable oleophilic ink, and subsequently curing the ink by exposure to radiation of an appropriate wavelength. The imaging may be performed "on-machine" (by a printing head mounted on the press itself) or "off-machine" upon either a cylindrical surface of a plated roller, or by using an X - Y plotter on a flat plate. <IMAGE>

Description

1 I- DIRECT IMAGING BY JET OR OTHER SCANNING PRINTER ONTO PRINTING PLATES

OF A PHOTOREACTIVE MATERIAL 2272866

BACKGROUND OF THE INVENTION

The present invention relates to a system and related method for cr(ating graphics and/or text on plates to be used in a iithographic printing press, and deals more particularly with such a system and related method wherein the printing plates are imaged using a jet printer which deposits a photocurable material onto the receiving surface of the printing plate at locations prescribed by digitized data representing the graphic and/or text to be printed.

On off-set printing presses, printing plates are used for printing an image and/or text on a substrate, such as paper, by causing the plate to first be inked and subsequently pressed against a rubber blanket to transfer ink which is split to the substrate to transfer the ink from select regions on the plate and onto the substrate. Fabrication of the printing plates can be accomplished in a number of ways. One of the most common ways of making such plates is the use of a standard photolithographic process. The plates used in this process are 2 commonly formed from a self-supporting material, usually a metal, i.e. aluminum, on which is coated a layer which is soluble to a solvent, such as water, but which becomes insoluble after it is exposed to light. A negative image mask transparency is placed in contact over the coated plate, usually in a vacuum frame, and the underlying soluble material is thereafter selectively exp9sed to light. Light passes through the transparent areas of the mask and polymerizes or otherwise modifies the coating making it insoluble. As such, the masked portions of the plate can be and are washed away with the subsequent application of an appropriate solvent leaving the light-affected material as distinct image areas on the plate. Dissolving away coating is often the source of problems. This process undesirably requires the complete removal of the soluble layer from the non-image area of the plate. The complete removal of the soluble layer from the non-image area of the plate is often not entirely obtainable, thus resulting in the contamination of these areas with residues which remain from the solubilized material. The washing solvents often are harmful to human breathing and/or ingestion. Also, in the case where a printing press is being used for publishing a newspaper and the urgency of the article going to 3 print is of high priority, this washing step undesirably adds time to this already time consuming process. Therefore, it is highly important that the material deposited have a quick set up capability with minimal use of solvents.

Hitherto, attempts have been made to simplify the preparation of printing plates. one such attempt has been-madein the fabrication of waterless lithographic plates as disclosed in U.S. Patent 4,003,312, issued on January 18, 1977 to Gunther. In one method of this patent, a printing plate fabrication process is disclosed wherein light sensitive curable silicone is applied as a layer to a master and the layer is selectively covered with an opaque substance such that the uncovered porti ons are subsequently cured by exposure to radiant energy. Thereafter, removal of the uncured silicone is accomplished by conventional means, such as, by washing with a suitable solvent. The step of removing the silicone layer by washing it with a suitable solvent often involves using pollutants inherent in solvents which are used to wash the plate. Also, while such washing steps, for the most part, adequately remove most of the deposited layer, often trace or residual material remains on the plate, especially where the plate has been roughened 4 by graining, thereby causing scumming and lessening of line definitions of the print. In another embodiment, it is disclosed to coat silicone on a master, cure the silicone and then image the silicone with a photopolymer which combines with the cured silicone to create ink receiving areas thereon. Again, the process of coating and subsequently curing the silicone are steps which add both time and expense to the plate fabrication process. As well, certain characteristics of the cured silicone coating, such as surface tension, may vary from plate to plate, thereby introducing uncertainty to the printing process.

In an attempt to create plates having regions designated by digitized data that are to be made oleophilic (oil accepting) thereby leaving the remaining portions hydrophilic (water accepting), ink jet printers have been used to deposit, for example, an oleophilic ink onto a plate in accordance with data representing point by point placement of where the oleophilic ink should and should not be deposited. An example of one such device is disclosed in U.S. Patent 4,833,486 issued on May 23, 1989 to Zerillo. The oleophilic ink imaged on the plates does not lend itself well to extensive A repeated use, as compared to an imaging material which is a hardened polymer or resin.

While imaging of plates need not necessarily occur with the plate mounted in the printing press, there are several favorable aspects to imaging in this manner. One benefit is that there is no movement of the plate to proper alignment which must occur subsequent to the plate having been mounted in the machine. Also, since the plate is imaged on the roller or cylinder in position on the press, registration between the plate and the roller is always maintained. This is particularly beneficial in the case of a multicolored printing press wherein a plurality of plate rollers are provided, each for applying a designated colored ink onto a substrate in a specified region.

Digitally formatted data representing the image to be printed is very suitable for driving an automatic spray jet printer. To begin with, an original which is scanned and input into a computer in digital format may be scaled to desired sizes using an appropriate software program to obtain the size change. The digitized data further is stored in memory thus avoiding the need to keep original films which are often large and take up file space. Furthermore, the stored data is not subject to change 6 due to shrinkage or other variables which could otherwise act on it, such as at times in the case where a negative film is placed in storage. Further, as digitized data, the image is capable of being disseminated to plural field printing stations, including plural imaging stations in a multicolored printing press as previously discussed above. Finally, the benefits derived from digitally formatted graphics allow enhanced color separation to be carried out by appropriate software to discriminate along paths between colors. However, when colored pictures are put through scanners which separate colors for the yellow, magenta, cyan and black inks used in printing, a transparency for each plate responsible for applying a different color is ordinarily required, which is not-the case for digitally stored data for directly imaging lithographic plates.

Accordingly, it is an object of the present invention to provide a predictable, low cost system for creating imaging plates to be used in an off-set printing apparatus wherein means are provided in the system for the quick set up of the imaged material without the need for chemicals or other pollutants known hitherto to be used in the plate production processy and/Or 7 to provide a system of the aforementioned type which eliminates the step of removing areas of the coatings originally deposited on the plates by using a spray jet printing device to deposit an ink receiving material on an uncoated plate, and/or to eliminate the use of transparencies which otherwise would be used to expose a plate and to thereby eliminate the related costs of handling and developing the film used to create the transparency, and/or to provide a system and related method of the aforementioned type for imaging offset printing plates wherein the art work, graphic and/or text to be imaged is digitally formatted in machine usable code for driving an imaging device or being altered mathematically to accommodate size considerations for the plate that is being imaged, and/or to reduce inaccuracies resulting from changes in size of photographic film during development, misalignment of film during exposure, and other handling of film during the plate making process, and/or to provide improvements generally.

8 SUMMARY OF THE INVENTION

The invention resides in a system and related method simplifying and reducing the time to prepare and make plates to be used in an off-set printer. The method of making a printing plate of the type where a material is imaged onto one surface of the plate for the purpose of receiving and subsequently allowing transfer of ink onto a substrate comprises the steps of: providing a plate having a top base surface and providing a jet printing apparatus having a jet head capable of covering selected portions of the top surface of the plate with an image forming material while leaving other portions of the top surface of the plate bare. Providing a source of liquid photoreactive material in the jet printing apparatus and using it as the image forming material. Providing data defining a graphic and/or text to be printed on a substrate and processing the data in a computer to generate machine operating data defining selected portions of the plate top base surface to be covered with the imaging forming material and other portions not to be covered by that material. Using the machine operating data to control the jet printing apparatus to deposit some of the liquid image forming material onto the top base surface so as to cover selected portions of the 9 top base surface of the plate with the liquid image forming material, and exposing the image forming material to radiant energy to form a hardened image. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a partially fragmentary perspective view showing a system embodying the present invention.

Fig. 2 is a vertical sectional view taken I through the apparatus of Fig. 1.

Fig. 3 is a perspective view of the print head and associated plate roller, with the plate roller being shown separate from its supporting structure.

Fig. 4 is an alternative embodiment of the system of the present invention wherein the pr inting press is capable of multicolored printing.

Fig. 5 is a perspective view of one embodiment of a plate imaging plotter of the drum type.

Fig. 6 illustrates in perspective view another embodiment of a plotter used for imaging printing plates.

Fig. 7 is a side elevation view of a third embodiment of the printing plate plotter.

Figs. 8a-8c illustrate different embodiments for digital formatting of art work.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 shows a printing system 2 embodying the invention having a jet printer 4 and an associated controller 6. In the embodiment shown in Fig. 1, the jet printer 4 is mounted in an offset printing press 8 for the purpose of imaging directly onto the outwardly directed print face 3 of a plate 1 that has previously been mounted in the machine.

The offset press 8 includes a plate cylinder or roller 10 which carries the printing plate 1 using a conventional mounting means 5 which includes means to pull the plate tightly over the roller 10, an impression roller 9 and a blanket roller 12 interposed between the plate roller 10 and the impression roller 9 and coacting with the cylinder roller 10 for engaging a substrate therebetween. Inking rollers 14 are also provided for coating selected areas of the plate roller 10 with ink while fountain rollers 16 are provided for wetting the other areas of the plate roller with a noninking liquid during a printing operation. The plate roller 10, the blanket roller 12, and the impression roller 9 are each drivingly coupled to a printing drive motor 7 in such a way as to cause the blanket roller to counterrotate synchronously relative to both the plate and impression rollers 1 11 when the drive motor 7 is operating. In this way, the plate roller splits ink to the blanket roller and thereafter the blanket roller prints on the substrate 18 as the substrate is caused to pass between the blanket and impression rollers. The fountain rollers 16 and the inking rollers 14 are freely rotatably mounted to the press and combine to selectively coat respective areas of the plate 1 with a an ink rejecting material and an ink receiving material. In the case of the inking rollers 14, an ink adheres to only those areas of the plate 1 which are previously made ink receiving by spraying photoreactive liquid with the jet printer 4 followed by exposure to actinic radiation as will hereinafter be discussed. The fountain rollers 16 are responsible for applying a liquid solution to the plate I to enhance line definitions and to reduce scumming, i.e. ink acceptance of the non-image areas of the plate. A gumming roller 17 is also provided where it is desired to coat the plate I with gum arabic, after the plate 1 has been sprayed by the printer 4 and exposed. The gumming roller 17 is moveably mounted on the press 8 between retracted and extended positions, in which extended position the gumming roller contacts the plate roller 10 to apply the gum to the accepting regions of the plate.

12 A supply of sheets of substrate material 18, usually paper, to be printed on is provided at 20 on the press and is advanced through it during a printing operation. As shown in Fig. 2, a single sheet of the substrate material 18 is driven through the press during a printing operation such that it is caused to pass between the impression roller 9 and the blanket roller 12 and is consequently pressed directly against the inked surface of the blanket roller to effect transfer of ink from theinked areas on the blanket roller to the substrate. In an alternative form, the press 8 may not include the blanket roller 9 interposed between the plate and the impression rollers 10 and 12, but rather only include the plate and impression rollers such that the substrate material is made to pass directly between the plate and impression rollers 10 and 12 to effect printing.

In accordance with the invention as best seen in Fig. 3, a jet printing head 22 is provided with each printer 4 and is mounted for movement transversely to the direction of paper flow T on ways 24,24 which straddle the associated plate roller 10. The jet head 22 is a standard commercially available jet printing head which may be a continuous pulse or a pressure pulse type device. one such commercially 1 13 available printer capable for such use is a Model 500 DESKJET made by Hewlett-Packard Co. Alternatively, the jet head 22 may be a piezo type jet, such as disclosed in U.S. Patent No. 4,599,626, entitled INK DROP EJECTING HEAD, issued on July 8, 1986 to Leonard G. Rich. The jet head is secured to a carriage 26 and is driven along the ways 24,24 by a carriage drive motor 28. A control,means 30 is provided for coordinating the transverse movement of the carriage 26 with the rotation of the plate roller 10 and in further coordination with controlled spraying of fluid from the jet head 22 to effect imaging of the plate 1. To this end, this means includes the controller or computer 6, a plate roller positioning motor 13, motor controls 33 and 37 linked to the computer 6 and associated respectively with the carriage positioning motor 28 and the plate positioning motor 13 for coordinating the imaging of the plate 1 in a line-by-line manner. The means 30 further includes a spray jet controller 27 linked to the computer 6 for modulating the spray pattern of liquid sprayed from the jet head in accordance with digitized machine operating data generated by the computer 6. As will hereinafter be discussed with reference to Figs. Sa-8c, the computer 6 generates the digitized operating data by first processing data 14 representing the image or text to be printed, which may be input to it in a variety of ways. This data is then converted into machine operating data to define selected portions of the surface 3 of the plate 1 to be covered with the image forming material and other portions not to be covered by such material. In this way, the print head 22 images the plate 1 by selectively sPrLying the photoreactive material 21 onto the plate surface 3 either as a positive or negative image.

During the imaging process, the computer 6 causes the positioning drive motor 13 to rotatably increment the plate roller 10 in a counterclockwise direction CC after each pass of the head 22 across the substrate. The jet head sprays a path having a width PW equal in dimension to the amount P by which the roller 10 is incremented after each pass of the head 22. The head begins its imaging operation at a known datum D, and from this datum, a plot is commenced and continues in coordination with the rotation of the drum until part or the entire surface 3 of the plate is covered. once imaging including light exposure of the plate 1 is completed, printing of the substrate 18 commences with the advancement of the substrate through the counter-rotating printing rollers 9 and 12. It is noted that the position 1 j drive motor 13 is drivingly rotatably coupled to the plate roller 10 through the intermediary of a one-way clutch which permits controlled rotation of the plate roller 10 by the positioning motor 13 in one direction, but which allows the plate roller 10 to be rotated by the drive motor 7 in the opposite direction independently of the positioning motor 13 during the printing operation.

In the embodiment of Fig. 1, only a single color printing operation is shown, and therefore only one plate roller and one set of printing and inking rollers are provided. However, in the case where a press 19 is used to print multicolored images and/or text on a substrate, there can be any number of plate and associated inking roller sets that may be used to print on a single unit of substrate material. For example, as shown in Fig. 4, the press 19 has a plurality of printing stations 11,11 each located along the travel path TT followed by the substrate 18. Each station in addition to having a blanket roller 121, a plate roller 101, an impression roller 91 and associated gumming, inking and fountain rollers 141,161,171, further includes a jet printer 41 having a print head 221 which images the plate mounted to an associated plate roller to create ink receiving areas corresponding to regions on the 16 substrate where the particular colored ink is to be applied. Each of the jet printers 41,41 in the multicolored press 19 is connected to a computer or controller 61 such that individual ones of the printers print on an associated plate under the control of a common computer. This arrangement is particularly well suited for multicolored printing presses in that once mounted in the press, the plates have a known registration which can be readily referenced by the common computer to direct each print head to deposit on the involved plate, the photoreactive material.

As set forth herein, the phrases "photoreactive material", "imaging material", and "photoreactive liquid" mean liquid compositions which are converted to solid material by exposure to radiant energy. Upon such conversion, the material forms a hardened image. Typically, such compositions are polymerized, cross-linked, or otherwise chemically reacted to form a hardened material by exposure to light. The light which causes the chemical reaction which hardens the material may be in any spectral range, but most typically is in the visible (wavelength between about 400 and 700 nm) and ultra-violet (wavelength less than about 400 nm) ranges.

17 Many photoreactive materials known to skilled practitioners may be utilized in the practice of the subject invention. Such materials are known by many names, including but not limited to positive working photopolymers, photoresiss, diazonium resins, and gelatins and polyvinyl alcohols. Photoresists and positive-working photopolymers are chemically very similar, in that they are water-soluble until polymerized or crosslinked by exposure to light. Such materials typically are based on, for example, esters of substituted acrylic acid, and contain photoinitiators. Upon exposure to light, the photoinitiators form free radicals which act on unsaturated parts of the ester molecule to cause polymerization. Photoresists also are based on phenolic resins containing photoinitiators such as iodoform. Photoresists often are used to resist acids, for example, in manufacture of computer chips. They are suitable for use in the present invention if the hardened material is sufficiently resistant to abrasion. Positive-working photopolymers are soluble in solvent, typically water, but polymerize or otherwise react to form hardened material which is essentially water-insoluble (and oleophilic) upon polymerization.

18 Other suitable photoreactive materials include diazonium resins, which comprise base resin made water soluble by combination with the diazonium moiety. Ultraviolet light causes the diazonium moiety to be replaced by a hydroxyl moiety,'thus rendering the base resin water-insoluble. Such materials are well-known to skilled practitioners. Commercially-available exaTples of such products include Diazo-4 powder, available from Fairmont Chemical Company of New Jersey.

In addition to these, other suitable photoreactive materials which typically are less durable and less shelf-stable than, for example, diazonium resins, also are suitable for use in the claimed invention. Examples of such materials include gelatin and polyvinyl alcohol-based systems. Such materials typically utilize dichromate or diazo photoreactive initiators.

The photoreactive materials suitable for application by jet spray apparatus in accordance with the invention are photoreactive liquids, typically solutions, suitable for application by such apparatus. Many of the known photoreactive materials described herein are highly viscous, often having a viscosity exceeding 500 cSt. Thus, skilled practitioners recognize that it may be necessary to 19 adjust the characteristics of photoreactive materials to accommodate application by spray jet. As set forth herein, various types of spray jets, including pressure pulse and piezo-type jet apparatus, can be used in practice of the invention. Thus, it may be necessary to adjust, inter alla, the solids concentration, the viscosity, the surface tension, or the pH, for example, of tho liquid to ensure proper operation of the spray jet mechanism and concomitant satisfactory application of the photoreactive material. Alternatively, or in conjunction therewith, it may be appropriate to adjust the operating characteristics of the spray jet apparatus. With the guidance provided herein, a skilled practitioner will be able to make the appropriate adjustment, whether to the characteristics of the photoreactive liquid, or to the spray jet apparatus itself, to suitably use photoreactive liquid in the spray jet apparatus.

As skilled practitioners recognize, commercially available photoreactive materials may contain additives, such as dyes and biocides. Such additives may be present in photoreactive material suitable for use in the present invention.

Typically, the hardened image formed by exposure of the photoreactive material described herein to light are oleophilic. Thus, they form inkreceiving surfaces for oleo-type inks. Although such photoreactive materials are preferred in the practice of the invention, a photoreactive liquid which forms a hydrophilic solid, thus forming an ink-receiving surface for water-based ink, also is suitable for use in the claimed invention where a printing system using an oleophilic ink reacting plate is desired.

The plate I employed by the method of the invention is a self-supporting sheet formed from a material possessing adequate mechanical stability, such as, creep resistance under stress, to permit use under varying conditions. The material selected is preferably one which is inexpensive and readily commercially available. The material suitable for these purposes are most commonly aluminum, but stainless steel may also be used. Additionally, the plate 1 can be comprised of a nonmetallic material, such as, heavy coated paper or an aluminum film-paper laminate. In the case where the plate is formed from paper, the material selected for it may be heavy gauge with a weight on the order of 80 pounds and preferably having a high clay content along with a coating, such-as filled polyvinyl alcohol/polyvinyl acetate to provide water absorbancy. In a preferred embodiment, utilizing photoreactive liquid which 21 forms an oleophilic ink receiving surface, the plate is washed with a gum arabic by the roller 17 subsequent to being imaged and exposed to atinic radiation to enhance desired hydrophilic areas on the plate. The plate 1 when formed from a metallic material has its print side or outer exposed surface 3 preferably roughened, such as by a graining processt to better hold thq imaged material sprayed from the print head 22.

The imaging material 21 deposited on the plate 1 by the jet head 22 is supplied in liquid form in a reservoir 42 carried by the head 22. The liquid is a photoreactive material that is sprayed in a microstream onto the print side 3 of the involved plate in a predetermined pattern and is thereafter caused to harden upon exposure to a radiant energy source. To this end, the press 8 includes an elongate ultraviolet lamp 40, fixed to the press so as to straddle the length of the plate roller. The lamp is also juxtaposed relative to the print head such that after a line is sprayed onto the plate 1, the roll 10 is incremented by an amount P to advance the deposited imaging material past the lamp 40 resulting in the material 21 curing to an insoluble coated area of the plate. Alternatively, the lamp 40 may be mounted to the head 22 in a trailing capacity 22 to expose the deposited material 21 as it is sprayed. This feature is important since it effects quick setting of the otherwise liquid imaging material 21.

The following example is illustrative of the imiention and the preferred embodiment.

1E - 1 A printing plate is formed and a substrate material is printed on as follows. An IBM PC using a windows-based software package was used to produce text of varying font sizes having a Helvetica1--ke type. The data representing this text was written to a disc-file in Postscript Page DeAcription format. A SCREENJET ink Jet printer, manufactured by Gerber Scientific Products, Inc., having a Hewlett-Packard DeskJet 500 thermal ink jet head,. was used to image the plate. The head is cartridge fed and writes with ink dots at-300/inch out of the ink-jet cartridge.

Imaging material, a solution of diazonium, resin, was prepared by dissolving in de-ionized water a quantity of Diazo-4 powder (Fairmont Chemical Company of New Jersey) sufficient to form a saturated 1 23 solution at room temperature. The saturated solution was then filtered twice and the resulting filtered solution was then diluted to a ratio of 3:1. This produced an aqueous solution of approximately 5% (by weight) diazonium resin. A 0.8 micron filter was attached to the output fitting of,the jet head. The ink jet head was emptied, flushed with deionized water, and then filled with the imaging solution.

An aluminum offset printing plate o f the type having a grained surface was provided and washed at least once with isopropyl alcohol to remove any scumming material existing on the grained surface. This surface was imaged by the SCREENJET and allowed to dry. The drying time was 3 minutes. Subsequently, the imaged areas of the plate were exposed to ultraviolet light for about 3 minutes using a metal-halide lamp. A slight change in the color of the imaged material was observed. The plate was gummed in the standard fashion, and then was used in an offset printer to print the image on the substrate sheets.

24 As set forth above, a commercially available photoresist may be used in place of the solution identified in Example 1. One such a material is sold commercially by London Chemical Company, Inc. of Bensenville, Illinois 60106 under the tradename KTI RESIST 930. This product has a viscosity, assupplied, of 510-625 cSt, and is crosslinked by 2.5 milliwatts/cM2 for 60 seconds of light having a wavelength of 400-420 nm. In cases where it is desirable to visually identify the imaged graphic, art work, or text on the plate, such as in the case where the plate has not been imaged in a printing press having imaging capabilities, but rather is imaged in a machine separate from the press, such as, by one of those shown in Figs. 8a-8c, the photoresist may be dyed for this purpose.

Once the imaging material 21 has hardened to form the graphic 44 disposed on the outwardly directed surface 3 of the plate 1, it is capable of either transferring ink to the blanket roller 3 or directly to the substrate, as in the case where only impression and plate rollers are used. In any case, it should be understood that the plate 1 after imaging and being moved past the radiant energy source 40, is ready for immediate Use. Also, to enhance the distinction between the hydrophilic and the oleophilic portions of the plate 1, the plate may be wetted at the fountain station 16 in a conventional manner during the printing operation with a gum, in the case where the oleophilic portions split ink, or with an oleophilic material in the case where the ink is hydrophilic. Alternatively, distilled water or another aqueous solution may be used.

In Figs. 5, 6 and 7, alternative plate imaging devices are shown which are separate, free standing units which stand apart from an offset printer. In Fig. 5, a drum printer 49 may be used, having internal components including a rotating drum 51 on which is mounted a plate 45 and cooperating print head 53. These components operate in a manner similar to the like components described with reference to Fig. 3 for imaging the involved plate. In Fig. 6, the imaging device is a flat bed plotter 46 having a support surface 48 on which is mounted a conveyor member 50. The conveyor 50 provides a means for on and off-loading a plate 58 in succession with another such plate ready to be imaged. Above the conveyor 50 is an X- carriage 52 which is capable of controlled movement in the indicated X coordinate direction. The X-carriage 52 also carries a Ycarriage 54 capable of moving in the indicated Y 26 coordinate direction and the Y-carriage also carries a jet print head 56 which sprays the photosensitive material 21 onto the plate 58. The plate 58 includes a plurality of openings 60,60 which receive registration pins 62,62 projecting upwardly from the conveyor 50. Housed within the carriage 52 is a radiant energy source 64 which moves with the carriage to subsequently e:pose the photoreactive imaging material 21 sprayed onto the plate 58.

In Fig. 7, a third embodiment of an imaging system is disclosed. A supply of plates 70,70 are maintained in a cassette 72 and are biased upwardly by a spring member 71 such that only a single plate is chambered at a time for handling. The system further includes a support surface 74 and a first beam 77 fixed above the support surface 74 along which is disposed a robotic handling means 80 which can be of the type disclosed in copending U.S. Application serial No. 07/660,280, entitled MEDIA HANDLING SYSTEM FOR PHOTOPLOTTER AND METHOD OF USE of Gerber Scientific Instruments Company. A second fixed beam 76 is also provided above the support surface 74 along which a jet print head 78 travels in a direction transversely to the direction A of plate advancement and on which is mounted the radiant energy source 64. A plate advancement means 82 is 27 provided for moving a plate to be imaged relative to the radiant energy source 64 and the head 78. The advancement means 82 includes for this purpose a rack and pinion type drive which moves the involved plate in coordinated movement relative to the head 78 during an imaging operation. In operation, a plate is picked up by the means 80 and moved from the cassette 72 and onto the sq port surface 74. The.P plate is then advanced relative to the radiant energy source 64 and the head 78 to concomitantly image and expose the photoreactive material 21.

Referring now to Figs. 8a-8c, and to the various different types of input devices used to convert graphic and/or textual matter into digital format, it should be seen that in the embodiment of Fig. 8a,-a lens 86 is used to focus an image of the art work or text 84 onto a scanning array 88. The graphic focused onto the scanning array is downloaded into a computer 90 in turn translated into machine useable code, i.e. digital form. The digital form of the data is then used to drive a jet plotter 92 of the type previously discussed. In the second embodiment of Fig. 8b, a machine scanner 94 is used to scan and encode art work or text 84 supported on a table. In the third embodiment of Fig. 8c, a composer 96 is provided and includes a conventional 28 viewing screen, mouse and keyboard 98,99, used to either type text and/or to draw art work which is then input into a processor 100 to drive a plotter 92.

From the foregoing detailed description, it will be apparent to those skilled in the art that the invention is described by way of illustration rather than limitatiori and is capLble of numerous modifications and/or substitutions. For example, the substrate material which is printed on may alternatively be a continuous web of material, rather than individual sheets of paper. Similarly, while the plates 1 have been disclosed as separate units it is possible to provide a web of plate material and advance it through a sprocket drive system, such as shown in Fig. 7, to deposit on the web an oleophilic image. Accordingly, the invention has been described by way of illustration rather than limitation.

29 CLATI45 1. A method of making a printing plate having a top base surface which is hydrophilic comprising the steps of providing data defining a graphic (44) and/or text to be printed on a subs-,:rate, processing said data in a computer (6) to generate machine operating data defining selected portions (44) of said top base surface to be covered with said image forming material and other portions not to be covered by said image forming material, providing a plate (1) having a top base surface (3), providing a jet printing apparatus (4) having a jet head (22) capable of covering selected portions of said top base surface of said plate with an image forming material whi-e leaving other portions of said top surface of sa-'d plate bare, said method being characterized by: providing a source (42) of photoreactive liquid. image forming material (21) in said jet printing apparatus which is hardenable to form oleophilic regions on said base structure, using said machine operating data to control said jet printing appe,ratus to deposit some of said liquid image forming - material onto said top base surface so as to cover said selected portions of said top base surface with said liquid imaging forming material 'and then expos'ng the image forming material so deposited it to radiant energy to form a hardened image.

2. A method as defined in claim-1 further characterized in that the hardened image is oleophilic.

3. A method as defined in claim 2 further characterized by providing the radiant energy as ultraviolet radiation.' 4. A method as defined in claim 3 further characterized in that said photoreactive liquid image forming material is mixed with a dye for coloring.

5. A method as defined in claim 4 further characterized in that said hardened image comprises a coloring matter.

6. A method as defined in claim 1 further characterized in that said plate is a non-metallic plate which carries a hydrophilic coating upon which the light hardenable image forming material is deposited.

1 31 7. A method as defined in claim 6 further characterized in that said plate is formed from heavy gauge paper with a hydrophilic coating.

8. A method as defined in claim 1 further characterized in that said plate is metallic and said top surface may be rendered hydrophilic by a coating after said image forming Mc-lterial is hardened.

9. A method as defined in claim 7 further characterized in that said plate is coated with filled polyvinyl alcohol/polyvinyl acetate.

10. A method as defined in claim 8 further characterized by said step of coating of said plate being done with a gum arabic.

11. A method as defined in claim 1 wherein the photoreactive liquid image forming material is selected from the group consisting of photopolymers, photoresists, diazonium resins, gelatin and polyvinyl alcohols.

12. A method as defined in claim 11 wherein the photopolymers are positive working photopolymers.

32 13. A method as defined in claim 11 wherein the photoreactive liquid image forming material comprises a photopolymer.

14. A method as defined in claim 11 wherein the photoreactive liquid image forming material comprises a diaza resin.

15. A method as defined in claim 8 further characterized in that the photoreactive liquid is a solution.

16. A method as defined in claim 15 -further characterized in that said solution comprises diazonium. resin and the solution is formed by initially dissolving said diaz6nium resin in water.

17. A method as defined in claim 1 further characterized by providing said jet printing apparatus (4) as part of an off-set printing machine (2) and using said jet print head to image said plate while it is mounted in the printing machine.

I.

33 18. A method as defined in claim 21 further characterized by fixing a radiant energy source (40,64) in said printing machine and juxtaposing it relative to the plate (1) mounted in the printing machine such that the involved plate is imaged in a line-by-line manner and the plate is advanced incrementally past the radiant energy source with each imaged line.

19. A method as defined in claim 18 further characterized by said data defining the image on said plate being created by focusing the image on a scanning array and thereafter inputting the information from the scanning array into said computer (Fig. 8a).

20. A method as defined in claim 18 further characterized by said data defining the image on said plate being created by mechanically scanning a graphic or text and thereafter inputting the information into said computer (Fig. 8b).

34 21. A method as defined in claim 18 further characterized by said data defining said image or said plate being created by a composer comprised of data input means connected directly to said computer (Fig. 8c).

22. A method as defined in claim 17 further characterized by providing a plurality of separate printing stations in said off-set printing machine each of which stations (111,111) include at least a plate roller (101, 101) and said plate mounted to it, providing each of said printing stations with a different colored ink to be printed on a substrate, providing each of said separate printing stations with said jet printing apparatus (41,41), and processing said data such that each jet printing apparatus associated with each of said inking stations is caused to cover the plate associated with that station with said image forming material to create ink receiving and ink rejecting regions corresponding respectively to where the involved color is to be printed and to where the involved color is not to be printed on the substrate (Fig. 4).

23. A method as defined in claim 22 further characterized by connecting said jet printing apparatus associated with each printing station to a common computer (61) and causing the computer to instruct each jet printing apparatus to image different regions of the plate.

1 36 24. A method of creating a printing plate comprising the steps of providing a metallic plate (1) having a hydrophilic top surface which is made up of the material of the metallic plate, providing data defining a graphic and/or text to be printed on a subst=ate, providing a jet printing apparatus (4) having a jet head (22) capable of covering selected portions of said top surface of said plate with an imag.i.ng material while leaving other portions of the top surface of said plate bare, processing said data to generate machine operating data defining selected portions of the top surface to be covered with said photareactive material and other portions not to be co,,e.red by said. photoreactive material, said method being characterized by:

providing a reservoir (42) of photoreactive.i mater-Jal which is hardenable to form oleophilic regions on the top surface of said metallic plate, usinc d jet 1 said machine operating data to control sai printing apparatus to deposit some of said phatoreactive material onto said top surface of said pr,.-r-t:ing plate so as to cover said selected portions of said top surface of said plate with said photoreactive material, and subjecting said te to photoreactive material on said printing pla,radiant energy (40,64) to cause it to harden and to form a hardenable oleophilic image.

37 25. A method of making or creating aprinting plate as described herein with reference to the accompanying drawings.

eo- e-2 g- - 17 Amendments to the claims have been filed as follows 1 A method of making a printing plate f or use in a lithographic press of the type using both inking and fountain rollers to selectively apply an ink and an ink rejecting material to the printing plate, respectively, and having a top base surface onto which is deposited a liquid image forming material comprising the steps of providing data defining a graphic (44) and/or text to be printed on a substrate, processing said data in a computer (6) to generate machine operating data defining selected portions (44) of said top base surface to be covered with said image forming material and other portions not to be covered by said image f orming material, providing a plate (1), providing a jet printing apparatus (4) having a jet head (22) capable of covering selected portions of said top base surface of said plate with an image forming material while leaving other portions of said top surface of said plate bare, said method being characterised by:

providing said plate made from a non resilient selfsupporting given material having an exposed top base surface defined by the same given material from which the plate is formed; providing a source (42) of photoreactive liquid image forming material (21) in said jet printing apparatus which is hardenable to form oleophilic regions of said base surface, using said machine operating data to control said jet printing apparatus to deposit some of said liquid image forming material onto said top base surface so as to cover said selected portions of said top base surface with said liquid imaging forming material, and then exposing the image forming material so deposited to radiant energy to cause the image forming material to harden and form an o leoph i 1 ic /hydrophobic ink receptive image and/or text on the exposed top base surface of the plate.

I- S - 2 A method as defined in claim 1 further characterised by providing the radiant energy as ultraviolet radiation.

3 A method as def ined in claim 2 further characterised in that said photoreactive liquid image forming material is mixed with a dye for colouring.

4 A method as defined in claim 3 further characterised in that said hardened image comprises a colouring matter.

A method as defined in claim 1 further characterised in that said plate is a non-metallic plate which carries a hydrophilic coating upon which the light hardenable image forming material is deposited.

6 A method as defined in claim 5 further characterised in that said plate is f ormed from heavy gauge paper with a hydrophilic coating.

7 A method as def ined in claim 1 further characterised in that said plate is metallic and said top surf ace may be rendered hydropilic by a coating after said image f orming material is hardened.

8 A method as defined in claim 6 further characterised in that said plate is coated with filled polyvinyl alcohollpolyvinyl acetate.

9 A method as def ined in claim 7 further characterised by said step of coating of said plate being done with a gum arabic.

A method as defined in claim 1 wherein the photoreactive liquid image forming material is selected from the group consisting of photopolymers, photorsists, diazonium I- 41D - resins, gelatin and polyvinyl alcohols.

11 A method as defined in claim 10 wherein the photopolymers are positive working photopolymers.

12 A method as defined in claim 10 wherein the photoreactive liquid image forming material comprises a photopolymer.

13 A method as defined in claim 10 wherein the photoreactive liquid image f orming material comprises a diazo resin.

14 A method as def ined in claim 7 further characterised in that the photoreactive liquid is a solution.

A method as defined in claim 14 further characterised in that said solution comprises diazonium resin and the solution is formed by initially dissolving said diazonium resin in water.

16 A method as def ined in claim 1 further characterised by providing said jet printing apparatus (4) as part of an off-set printing machine (2) and using said jet print head to image said plate while it is mounted in the printing machine.

17 A method as def ined in claim 21 further characterised by fixing a radiant energy source (40,64) in said printing machine and juxtaposing it relative to the plate (1) mounted in the printing machine such that the involved plate is imaged in a line-by-line manner and the plate is advanced incrementally past the radiant energy source with each imaged line.

18 A method as defined in claim 17 further 1 characterised by said data defining image on said plate being created by focusing the image on a scanning array and thereafter inputting the information from the scanning array into said computer (Fig 8a).

19 A method as def ined in claim 17 further characterised by said data defining the image on said plate being created by mechanically scanning a graphic or text and thereafter inputting the information into said computer (Fig 8b).

A method as def ined in claim 17 further characterised by said data defining said image or said plate being created by a composer comprised of data input means connected directly to said computer (Fig 8c).

21 A method as defined in claim 16 further characterised by providing a plurality of separate printing stations in said off-set printing machine each of which stations (111, 111) include at least a plate roller (101, 101) and said plate mounted to it, providing each of said printing stations with a different coloured ink to be printed on a substrate, providing each of said separate printing stations with said jet printing apparatus (41, 4 1), and processing said data such that each jet printing apparatus associated with each of said inking stations is caused to cover the plate associated with that station with said image forming material to create ink receiving and ink rejecting regions corresponding respectively to where the involved colour is to be printed and to where the involved colour is not to be printed on the substrate (Fig 4).

22 A method as def ined in claim 21 further characterised by connecting said jet printing apparatus associated with each printing station to be common computer -- tz- I-- (61) and causing the computer to instruct each jet printing apparatus to image different regions of the plate.

23 A method of creating a printing plate for use in a lithographic press of the type using both inking and fountain rollers to selectively apply an ink and an ink rejecting material to the printing plate, respectively, said method comprising the steps of providing a metallic plate (1) having a hydrophilic top surf ace which is made up of the material of the metallic plate, providing data defining a graphic and/or text to be printed on a substrate, providing a jet printing apparatus (4) having a jet head (22) capable of covering selected portions of said top surface of said plate with an imaging material while leaving other portions of the top surface of said plate bare, processing said data to generate machine operating data defining selected portions of the top surface to be covered with said photoreactive material and other portions not to be covered by said photoreactive material, said method being characterised by:

providing a reservoir (42) of photoreactive material which is hardenable to form oleophilic regions on the top surface of said metallic plate, using said machine operating data to control said jet printing apparatus to deposit some of said photoreactive material onto said top surface of said printing plate so as to cover said selected portions of said top surface of said plate with said photoreactive material, and subjecting said photoreactive material on said printing plate to radiant energy (40, 64) to cause it harden and to form on said top metallic surface of said plate a hardened oleophilic/hydrophobic image thereon.

24 A method of making or creating a printing plate as described herein with reference to the accompanying drawings.