Patent Application
20110249057
Lithographic and gravure printing techniques have been refined and improved for many years. The basic principle of lithography includes the step of transferring ink from a surface having both ink-receptive and ink-repellent areas. Offset printing incorporates an intermediate transfer of the ink. For example, an offset lithographic press may transfer ink from a plate cylinder to a rubber blanket cylinder, and then the blanket cylinder transfers the image to a surface (e.g., a paper web). In gravure printing, a cylinder with engraved ink wells makes contact with a web of paper and an electric charge may assist in the transfer of the ink onto the paper.
Early implementations of lithographic technology utilized reliefs of the image to be printed on the plate such that ink would only be received by raised areas. Modern lithographic processes take advantage of materials science principles. For example, the image to be printed may be etched onto a hydrophilic plate such that the plate is hydrophobic in the areas to be printed. The plate is wetted before inking such that oil-based ink is only received by the hydrophobic regions of the plate (i.e., the regions of the plate that were not wetted by the dampening process).
Conventionally, all of these printing techniques have a similar limitation in that the same image is printed over and over again. This is due to the fact that conventional lithographic printing uses plates wherein each plate has a static (i.e., unvarying) image, whether it be a relief image or an etched hydrophobic image, etc. Gravure printing also uses a static image which is engraved in ink wells on a cylinder. There is a substantial overhead cost involved in making the plates that are used by a lithographic press or cylinders/cylinder sleeves used by a gravure press. Therefore, it is not cost effective to print a job on a lithographic or gravure press that will have few copies produced (i.e., a short-run job). Also, conventional lithographic and gravure presses have not been used to print variable data (e.g., billing statements, financial statements, targeted advertisements, etc.) except in cases where such presses have been retrofitted with inkjet heads, albeit at high cost and slower speeds. Typically, short-run jobs and/or jobs that require variability have been typically undertaken by laser (such as electrostatic toner) and/or ink jet printers.
Traditionally, many printed articles such as books and magazines have been printed using a process that involves a great deal of post-press processing. For example, a single page or set of pages of a magazine may be printed 5,000 times. Thereafter, a second page or set of pages may be printed 5,000 times. This process is repeated for each page or set of pages of the magazine until all pages have been printed. Subsequently, the pages or sets of pages are sent to post-processing for assembly and cutting into the final articles.
This traditional workflow is time- and labor-intensive. If variable images (i.e., images that vary from page-to-page or page set-to-page set) could be printed at lithographic image quality and speed, each magazine could be printed in sequential page (or page set) order such that completed magazines would come directly off the press. This would drastically increase the speed and reduce the expenses of printing a magazine.
Ink jet printing technology provides printers with variable capability. There are several ink jet technologies including bubble jet (i.e., thermal) and piezoelectric. In each, tiny droplets of ink are fired (i.e., sprayed) onto a page. In a bubble jet printer, a heat source vaporizes ink to create a bubble. The expanding bubble causes a droplet to form, and the droplet is ejected from the print head. Piezoelectric technology uses a piezo crystal located at the back of an ink reservoir. Alternating electric potentials are used to cause vibrations in the crystal. The back and forth motion of the crystal is able to draw in enough ink for one droplet and eject that ink onto the paper.
The quality of high speed color ink jet printing is generally orders of magnitude lower than that of offset lithography and gravure. Furthermore, the speed of the fastest ink jet printer is typically much slower than a lithographic or gravure press. Traditional ink jet printing is also plagued by the effect of placing a water-based ink on paper. Using a water-based ink may saturate the paper and may lead to wrinkling and cockling of the print web, and the web may also be easily damaged by inadvertent exposure to moisture. In order to control these phenomena, ink jet printers use certain specialized papers or coatings. These papers can often be much more expensive than a traditional web paper used for commercial print.
Furthermore, when ink jet technology is used for color printing, ink coverage and water saturation may be increased. This is due to the four color process that is used to generate color images. Four color processing involves laying cyan, magenta, yellow and black (i.e., CMYK) ink in varying amounts to make a color on the page. Thus, some portions of the page may have as many as four layers of ink if all four colors are necessary to produce the desired color. Additionally, the dots produced by an ink jet printer may spread and produce a fuzzy image. Still further, inks used in ink jet printers are extremely expensive as compared to inks used in traditional lithography or gravure printing. This economic factor alone makes ink jet technology unsatisfactory for the majority of commercial printing applications, particularly long run applications.
Laser printing has limited viability for high speed variable printing at present, because production speeds are still much slower than offset and gravure, and the material costs (e.g., toner, etc.) are extremely high compared to commercial offset or gravure ink prices. Laser color is also difficult to use for magazines and other bound publications, because the printed pages often crack when they are folded.
Printing techniques have been found to be useful in the production of other articles of manufacture, such as electrical components, including transistors and other devices. Still further, indicia or other markings have been printed on substrates other than paper, such as plastic film, metal substrates, and the like. These printing techniques may use those described above to print paper substrates, in which case these techniques suffer from the same disadvantages. In other cases flexography may be used, which, like lithography, requires the prepress preparation of plates.
In accordance with one aspect of the present invention, a method of transferring a principal substance, includes the steps of applying a principal substance onto a first surface and depositing drops of a gating agent onto a first portion of the principal substance after the principal substance is applied to the first surface. The deposition of each drop is individually controlled and a second portion of the principal substance applied to the first surface is not covered by the gating agent. The method further includes the step of transferring the second portion of the principal substance from the first surface to a second surface.
In accordance with a further aspect of the present invention, an apparatus for transferring a principal substance comprises an application apparatus for applying a principal substance to a surface and a depositing apparatus for depositing a gating agent on top of the principal substance wherein at least one portion of the principal substance is not covered by the gating agent. The apparatus further includes means for transferring the at least one portion of the principal substance not covered by the gating agent from the surface to a print medium.
According to another aspect of the present invention, a method of printing comprises the steps of moving a surface through a plurality of passes and, during each pass of the surface, applying a principal substance to the surface and covering selected first portions of the principal substance with a gating agent. The method further includes the step of transferring second portions of the principal substance to a print medium wherein the second portions are substantially defined by the selected first portions.
According to yet another aspect of the present invention, a printing system includes a surface moved through a plurality of passes and a principal substance applicator that applies a principal substance to the surface. A gating agent applicator covers first portions of the principal substance with a gating agent and a transfer system transfers second portions of the principal substance to a print medium wherein the second portions are defined by the first portions. The principal substance applicator, the gating agent applicator, and the transfer system operate in sequence during each pass of the surface and the gating agent substantially blocks transfer of at least some of the first portions of the principal substance.
Other aspects and advantages of the present application will become apparent upon consideration of the following detailed description and the attached drawings, in which like elements are assigned like reference numerals.
If a blanket cylinder is used, such as blanket cylinder 110, the inked image may be transmitted from plate cylinder 104 to blanket cylinder 110. Then, the image may be further transferred to web 112 (e.g., paper) between blanket cylinder 110 and impression cylinder 114. Using impression cylinder 114, the image transfer to web 112 may be accomplished by applying substantially equal pressure or force between the image to be printed and web 112. When a rubber blanket is used as an intermediary between plate cylinder 104 and web 112, this process is often referred to as “offset printing.” Because plate 102 is etched and then mounted on plate cylinder 104, a lithographic press is used to print the same image over and over. Lithographic printing is desirable because of the high quality that it produces. When four printing decks are mounted in series, magazine-quality four color images can be printed.
An illustrative apparatus in accordance is illustrated in
Aqueous jet system 214 may contain a series of ink jet cartridges (e.g., bubble jet cartridges, thermal cartridges, piezoelectric cartridges, etc.). A bubble jet may emit a drop of ink when excited by a heater. A piezoelectric system may eject a drop of ink when excited by a piezoelectric actuator. The drop is emitted from a tiny hole in the ink jet cartridges. The cartridges may contain any number of holes. Commonly, ink jet cartridges can be found with six hundred holes, often arranged in two rows of three hundred.
The aqueous jet system 214 may be used to emit an aqueous solution (e.g., water, ethylene glycol, propylene glycol, or any combination thereof). In some embodiments as disclosed herein, the aqueous solution may contain one or more surfactants, such as Air Products' Surfynol®. Such surfactants may contain a hydrophilic group at one end of each molecule and a lipophilic group at the other end of each molecule. Adding one or more surfactants to the aqueous solution may improve the surface tension properties of the aqueous solution.
The aqueous jets of aqueous jet system 214 may be used to place aqueous solution on a hydrophilic plate in much the same way that a drop of ink is placed on a piece of paper by an ink jet. In some embodiments, the aqueous solution may be ejected through traditional ink jet nozzles (i.e., heads). Such ink jet nozzles may include, for example, ink jet nozzles manufactured by HP, Lexmark, Spectra, Canon, etc. In some embodiments, aqueous jet system 214 may support variable print speeds and output resolutions.
The aqueous jet system 214 may be used to “print” or jet a negative image of the image to be printed, or any portion thereof, on plate cylinder 206. For example, as described in more detail below with regard to
In some embodiments as disclosed herein, a vacuum source or heat source 215 may be positioned next to or near aqueous jet system 214. In some embodiments, vacuum source or heat source 215 may be integrated with aqueous jet system 214. The vacuum source or heat source may be used to reduce the size of the individual drops of aqueous solution placed by aqueous jet system 214 by blowing, drying, and/or heating the aqueous solution after it is printed onto plate 204 or plate cylinder 206. Alternatively, any process parameter, including ambient conditions, such as humidity levels, could be manipulated that could affect the drop formation. The ability to control drop size of the aqueous solution may improve the quality of the printed image.
As plate cylinder 206 completes its revolution, after passing the image to blanket cylinder 208, it passes through cleaning system 212, which may remove ink and/or aqueous solution residue so that plate cylinder 206 may be re-imaged by aqueous jet system 214 during the next revolution (or after a certain number of revolutions). Cleaning system 212 may comprise a rotary brush, a roller having a cleaning solution, a belt, a cleaning web treated with a cleaning solution, an apparatus for delivering heat and/or air, an electrostatic apparatus, or any other suitable means of removing ink, aqueous solution residue, or both, from plate cylinder 206. In some embodiments, blanket cylinder 208 may also have a cleaning system similar to cleaning system 215 to clean any residual material from blanket cylinder 208 after the image has been transferred to web 216.
In some embodiments, plate cylinder 206 may have all of the static data for a particular print job etched onto plate 204 by traditional lithographic techniques. Aqueous jet system 214 may then be used to image only variable portions of the job represented by the variable or semi-fixed image data on specified portions of plate 204.
In other embodiments, plate 204 may not be used. Instead, as is understood in the art, the surface of plate cylinder 206 may be treated, processed, or milled to receive the aqueous solution from aqueous jet system 214. Additionally, plate cylinder 206 may be treated, processed, or milled to contain the static data and be receptive to the aqueous solution to incorporate variable data. In these and any other embodiments herein, blanket cylinder 208 may be eliminated entirely, if desired, by transferring the image directly to web 216.
In some embodiments, one or more of plate 204, plate cylinder 206, and blanket cylinder 208 may be customized or designed to work with various properties of aqueous jet system 214 or the aqueous solution. For example, as is understood in the art, one or more of these plates and cylinders may be specially processed or milled to only accept solution ejected by print heads of a particular resolution or dot size. The plates and cylinders may also be specially processed to accept certain types of aqueous solutions and reject others. For example, the plates and cylinders may accept solutions of a certain volume, specific gravity, viscosity, or any other desired property, while rejecting solutions outside the desired parameters. This may prevent, for example, foreign agent contamination and allow for one aqueous solution to be used in the printing process and another aqueous solution (with different physical properties) to be used in the cleaning process. In other embodiments, customary, general-purpose plates and cylinders are used.
As shown in
The aqueous jet system and cleaning system may be mounted in other arrangements as well. As shown in the example of
As shown in
One benefit of an embodiment like that shown in
Properties of the aqueous solution or gel (e.g., viscosity or specific gravity) and of the print medium (e.g., using bond paper, gloss paper, or various coating techniques) may be varied to achieve a desirable interaction between the protective negative image that is printed with the aqueous jet system and the print medium. For example, if image sharpness is desired, it may be beneficial to choose an aqueous solution that will not be absorbed at all by the print medium. However, if some transfer of ink is desirable even from the areas covered with the output of the aqueous jet system, it may be beneficial to use a print medium that quickly absorbs the aqueous solution so that some ink transfer is also able to occur from the covered areas.
Once the positive image has been protected, rotating imaging cylinder 808 next encounters stripping system 818. Stripping system 818 is used to strip away the ink from the unprotected areas of imaging cylinder 808. In other words, any ink that was not protected by aqueous jet system 814 and is therefore not part of the image to be printed, is stripped away from the imaging cylinder. Stripping system 818 may be, for example, a series of blank webs that can be used to pull the unprotected ink away from the imaging cylinder. Stripping system 818 may alternatively employ a reverse form roller as described below. The protected ink image is then transferred to the print medium.
The transfer of the protected ink image may be achieved by transferring both the protective aqueous layer and the protected ink to web 816. Alternatively, stripping system 818 may remove the protective aqueous layer so that the originally protected ink may be transferred to the web without the protective aqueous layer. In some embodiments, stripping system 818 may remove the protective aqueous layer at the same time it removes the unprotected ink (i.e., the ink not covered by the protective aqueous layer), leaving only the originally protected ink to be transferred to web 816. In such an embodiment, a reverse form roller may be used to strip off the unprotected ink and aqueous solution. The reverse form roller may also be used to return the stripped ink to inking system 802. In other words, the unused ink may be recycled by stripping system 818. Any other suitable method may be used to transfer the protected ink image to web 816.
Another alternative embodiment is illustrated by printing deck 900 of
For example, aqueous jet system 914 may be used to print a positive image onto imaging cylinder 908. Then, a heat source, e.g., dryer 918 or any other suitable means of evaporating the water, may be used to dry the aqueous solution. This will leave the block copolymer bonded to imaging cylinder 908 at the location at which it was printed by aqueous jet system 914. The block copolymer should be chosen such that one end bonds with surface material of the imaging cylinder while the other end is lipophilic. If a naturally hydrophilic imaging cylinder is used, the imaging cylinder will be lipophilic everywhere that aqueous jet system 914 printed the block copolymer, and hydrophilic everywhere else. The imaging cylinder may now be used in the known lithographic process. For example, ink may be, constantly applied to imaging cylinder 908 by inking system 902. The image may be then be transferred to the print medium (e.g., web 916 between imaging cylinder 908 and impression cylinder 910).
The embodiment of
In an alternative embodiment of
In yet another alternative of the
Alternatively, imaging cylinder 908 may have a charged surface that is controllable to change the charged property of a particular point on the imaging cylinder at a particular time. In other words, points on imaging cylinder 908 may be toggled between positively and negatively charged to attract and repel the surfactants at the appropriate time in the printing process. In fact, one may use two or more imaging cylinders, such that each cylinder is used to print a portion of the imaged output, so that when one cylinder is being charged to repel ink, the other is being charged to attract ink. In this fashion, the reversal of charge does not impact the production process. Still further, each cylinder could be sized and positioned such to allow for recovery time between imaging cycles while the system performs continuous printing.
As evidenced by the above description, surfactant block copolymers having various properties may be used with imaging cylinders having various material properties to achieve an imaging cylinder that has a selectively oleophilic and hydrophilic surface. The physical bond created between the surfactant and the imaging cylinder's surface allows the imaging cylinder to repeat the same image multiple times or to selectively vary the image in any given rotation of the imaging cylinder. By taking advantage of the material properties of the imaging cylinder and the block copolymer surfactants, a durable, yet variable, imaging system having the quality of known lithographic printing techniques may be achieved.
Surfactants like those described above are sold in various forms (e.g., solid, powder, aqueous solution, gel, etc.). Any desirable form may be used in accordance with the present disclosure.
To generate the variable image, a negative image of the variable image may be printed by aqueous jet system 1014 directly onto web 1012. Before web 1012 reaches aqueous jet system 1014, web 1012 may be coated to prevent web 1012 from absorbing the aqueous solution. Thus, when the portion of web 1012 to receive the variable image makes contact with the portion of blanket cylinder 1008 transferring the ink for the variable image, web 1012 selectively receives the ink only in the areas not previously printed on by aqueous jet system 1014. The standard lithographic deck operates as though it is printing the same image repeatedly (e.g., a solid rectangle). However, web 1012, which is first negatively imaged by aqueous jet system 1014, only selectively receives the ink in the solid rectangle on blanket cylinder 1008 to create the variable image on web 1012.
Coating system 1016 may be an entire deck of its own for applying the coating. Alternatively, coating system 1016 may be any suitable alternative for applying a coating to web 1012 to reduce its ability to absorb the aqueous solution. For example, coating system 1016 may include a sprayer that sprays a suitable solution onto web 1012. The solution may prevent web 1012 from absorbing all or some of the aqueous solution.
In any of the foregoing embodiments, a blanket and plate cylinder combination may be replaced by a single imaging cylinder and vice versa. In any case, it may be desirable to pair a soft imaging/blanket cylinder with a hard impression cylinder (e.g., a silicone imaging/blanket cylinder and a steel impression cylinder). Alternatively, a hard imaging/blanket cylinder may be paired with a soft impression cylinder (e.g., a ceramic imaging/blanket cylinder and a rubber impression cylinder).
In some embodiments, it may be desirable to employ a silicone imaging cylinder to create a “waterless” system. In such embodiments, the imaging cylinder may have a silicone surface that is entirely oleophobic. As known in the art of waterless lithography, such cylinders may be developed (e.g., etched) such that portions of the cylinder's surface become oleophilic. Because the silicone is naturally oleophobic, there is no need to wet the cylinder before applying ink to the cylinder's surface. In some embodiments herein employing a silicone imaging cylinder, an aqueous solution may be used that includes silicone-based surfactants or other suitable materials that may be both oleophilic and attracted to the imaging cylinder's silicone surface. Thus, the imaging cylinder may be variably imaged with such an aqueous solution as described herein. If necessary, an appropriate cleaning mechanism may be used to clear any residual aqueous solution or ink from the imaging cylinder.
Multiple decks like those shown in
The entire press may be managed by a single data system, such as data system 1218, that controls RIP controllers 1210, 1212, 1214, and 1216, which in turn control decks 1202, 1204, 1206, and 1208, respectively. Data system 1218 may be provided with customer input 1224 via database 1220 and variable data source 1222. Database 1220 may include image data, messages, one-to-one marketing data, etc.
In some embodiments, database 1220 contains all the layout information and static image information for the job to be printed, while variable data source 1222 contains all the variable data. For example, customer input 1224 may provide customer data (e.g., layout and content preferences) to database 1220. Variable data source 1222 may store personalized text (e.g., the customer's name and location) and graphics. Data system 1218 may then access both database 1220 and variable data source 1222 in order to print a job. Database 1220 and variable data source 1222 may include any suitable storage device or storage mechanisms (e.g., hard drives, optical drives, RAM, ROM, and hybrid types of memory). Press 1200 may be fed by roll or sheet input 1226. Output 1228 of the press may also be in the roll or sheet format. Additionally, output 1228 of press 1200 may be fully-bound or may be prepared for optional post-processing.
One or more of the aqueous jet systems, cleaning systems, stripping systems, and vacuum or heating systems described in the embodiments above may be electronically controlled via data system 1218. For example, in a typical usage scenario, data system 1218 may access raster image data (or any other type of image data, including, for example, bitmap data, vector graphics image data, or any combination thereof) from database 1220 and/or variable data source 1222. In some embodiments, the image data may be stored in page description code, such as PostScript, PCL, or any other PDL code. The page description code may represent the image data in a higher level than an actual output bitmap or output raster image. Regardless of how the image data is stored, data system 1218 may cause the aqueous jet system disclosed herein to print a negative image representing the image data (or any portion thereof) in aqueous solution to a plate or plate cylinder. In some embodiments, as described above, only the data represented by the variable image data may be printed in aqueous solution on the plate or plate cylinder.
Controlling the entire press from a single data system, such as data system 1218, may enable a user to take advantage of form lag techniques. Form lag relates to the timing of multiple variable printing devices acting on the same document. Certain data may need to be printed by one deck while another portion of data may need to be printed by another deck on the same document. In this respect, it may be beneficial to delay the transmission of data to the latter deck, because the document may pass through several intermediary decks before reaching the latter deck. By efficiently managing form lag, image resolution and placement may be improved.
The aqueous jet systems of the various embodiments disclosed herein may be arranged in a number of ways. For example,
The aqueous jet units may be known print cartridge units such as those manufactured by HP, Lexmark, Spectra, Canon, etc. Each jet unit may comprise any number of small holes for emitting the aqueous solution. As shown in
Alternatively, aqueous jet units 1402 may be arranged in series as shown in cylinder 1400 of
As should be evident from the foregoing, any agent may be utilized that blocks the application of ink as desired. Alternatively, a different form of agent may be used that facilitates application of a substance to a substrate. Because the embodiments disclosed herein comprehend the use of either (or both) blocking and transfer-aiding compositions, or one or more compositions that have both properties, reference will be made hereinafter to a gating agent that may have either or both of these capabilities with respect to a principal substance. Specifically, the gating agent may block transfer of all, substantially all, or some portions of the principal substance. The gating agent may alternatively, or in addition, aid in transfer of all, substantially all, or a portion of the principal substance, or may block some portion(s) and aid the transfer of other portion(s) of the principal substance. In the case of the examples described above, the principal substance may be an ink, the substrate may be a web of paper, and the selective portions of the principal substance may be image areas. Gating agent may be applied using one or more ink jet heads either to a plate or directly to a blanket cylinder, then ink may be applied in a non-selective fashion to the plate or blanket cylinder, and then the ink may be transferred from the image areas on the plate or blanket cylinder to the web of paper. In the event that the gating agent and the ink are applied directly to the blanket cylinder, the plate cylinder need not be used. Particular printing applications that may benefit include static print jobs (particularly, but not limited to, short runs), or variable or customizable print jobs of any size, for example, targeted mailings, customer statements, wallpaper, customized wrapping paper, or the like.
The apparatus and methods disclosed herein are also relevant in other industries and other technologies, for example, textiles, pharmaceuticals, biomedical, and electronics, among others. Variably customizable graphics or text, or a principal substance having enhanced sealing properties or water or fire resistance may be selectively applied to webs of textiles such as may be used to manufacture clothing or rugs. In the pharmaceutical industry, the principal substance may be a drug, a therapeutic, diagnostic, or marking substance other than an ink, or a carrier for any other type of substance. In biomedical applications, for example, the principal substance may be a biological material or a biocompatible polymer. In electronics applications, the principal substance may be an electrically conductive or insulative material that may be selectively applied in one or more layers on the substrate. Other electronic applications include production of radio frequency identification (“RFID”) tags on articles. Other industries may also benefit from selective application of a principal substance to a substrate. For example, the principal substance may be a thermally conductive or insulative material selectively applied over components of an item of manufacture, for example, a heat exchanger, a cooking pan, or an insulated coffee mug. The principal substance may also be a material with enhanced absorptive, reflective, or radiative properties, some or all of which may be useful in other items of manufacture, for example, when the principal substance is selectively applied to components of an oven, a lamp, or sunglasses. Still further uses for the principal substance may include customizable packaging films or holograms (via selective filling of refractive wells prior to image forming). Moreover, the technology could be applied to fuel cell manufacturing and the principal substance may include functional polymers, adhesives and 3-D interconnect structures. In applications for the manufacture of micro-optical elements, the principal substance could be an optical adhesive or a UV-curing polymer. Yet a further application may be display manufacturing wherein the principal substance is a polymer light-emitting diode material.
The gating agent may be applied as, for example, an aqueous fluid by being selectively sprayed directly onto the substrate or onto an intermediate surface or directly onto the principal substance using ink jet or other precisely controllable spraying or application technology. An aqueous fluid may generally have a low viscosity and a reduced propensity to form clogs, and is therefore advantageous for use with an ink jet head. However, the gating agent may also be applied using ink jet technology in a form other than an aqueous fluid. Further, the gating agent is not limited to being a fluid at all and may be applied as a solid, for example as a thin film, a paste, a gel, a foam, or a matrix. The gating agent could comprise a powdered solid that is charged or held in place by an opposite electrostatic charge to prevent or aid in the application of the principal substance.
As an example, a liquid gating agent in the form of a solvent may be applied by one or more ink jet heads to a plate and a powdered ink colorant dispersible in the solvent may be deposited over the entire surface of the plate to form a liquid ink in situ in the jetted areas. Powder in the non-jetted areas may be removed (e.g., by inverting the plate so that the powder simply falls off the plate, by air pressure, centrifugal force, etc), thereby resulting in inked and non-inked areas. Alternatively, a charged powdered ink colorant may be applied over an entire plate surface (or substantially the entire plate surface or only a portion of the plate surface) and may be retained on the plate by an electrostatic charge applied to the plate. The solvent may then be jetted onto the areas to be imaged to form liquid ink in such areas, and the electrostatic charge removed so that the powder in the non-wetted areas can be removed. In either event, the resulting image may thereafter be applied to a substrate, for example a web of paper.
Any of the systems described herein may be modified to allow formation of different drop sizes of gating agent. For example, ink jet heads manufactured by HP may be used to obtain drop sizes on the order of 14 picoliters (pl) up to 1200 dots per inch (dpi) resolution whereas ink jet heads manufactured by Xaar are capable of ejecting 3 pl drops at 360 dpi but are also able to eject 6 pl, 9 pl, and 12 pl drops. Disparate ink jet head technologies, such as both HP and Spectra, may be used in a single system to produce a wider range of drop sizes. The resolution of the resulting imaged areas can be controlled through appropriate selection of the ink jet head(s) used to apply the gating agent. In general, a larger drop size is more susceptible to forced wetting of areas to be imaged. This forced wetting can result from merging of adjacent jetted drops when the image is transferred between surfaces (such as in the nip area between a plate and blanket) and can cause a decrease in image quality due to a reduction in print density. Such forced wetting can be minimized by the addition/removal of one or more constituents and/or changing or adjusting one or more physical properties of the gating agent. For example, reducing certain surfactants may reduce ghosting while utilizing, adding, and/or substituting other surfactants may also improve image quality. Alternatively, one could apply an electrostatic charge to a cylinder that is opposite in the polarity to the charge of the gating agent applied to the cylinder. The resulting electrostatic attraction may reduce or eliminate forced wetting.
Still further, increasing the viscosity of the gating agent and/or increasing the surface tension thereof, and/or using a supporting agent and/or mechanical structure for non-image and image areas, respectively, such that the boundaries between image and non-image areas are maintained can reduce spreading, thus improving quality. Other chemical and/or materials science properties might be utilized to reduce or eliminate this effect. Viscosity modifying agents may include propylene glycol, cellulosic materials, xanthan gum, or Johnson Polymer's Joncryl® 678, to name a few. The gating agent may also include a thixotropic fluid that changes viscosity under pressure or agitation. Increasing surface tension of the gating agent can also reduce spreading. Surface tension modifiers can include poloxamer (e.g., BASF's Pluronic®) or Air Products' Surfynols®, among others. In addition, other agents may be incorporated in the gating agent composition such as anticurl and anticockle agents, blocking agent anchors, litho ink modifiers, receiving surface modifier, antiseptic agents, biocides, and pH adjusters and maintainers.
The types and/or physical characteristics and/or chemical compositions of the ink(s) or other principal substance(s) may be selected or modified to obtain desired results. For example, by controlling the surface tension of the ink, color-to-color bleed and showthrough on the opposite side of the paper can be eliminated. As a further example, one or more ink(s) used in waterless printing applications may be employed together with jetted gating agent (whether the latter is aqueous or non-aqueous) to block or promote transfer of ink from plate to paper. In the case of the use of waterless printing ink(s) with an aqueous gating agent, the composition of the gating agent may be adjusted in view of the lipophilic characteristics of such ink(s) so that the gating agent has a molecular structure that attracts and/or repels the ink(s) as necessary or desirable. Alternatively, jetted gating agent applied initially to a hydrophilic plate may include one or more hydrophilic components that bond with the plate and one or more other components that bond with or repel ink molecules.
As a still further example, a phase change of the gating agent, or the principal substance, or both, may be employed to prevent and/or promote substance blocking or transfer/collection. For example, gating agent may be selectively jetted onto a surface, such as a plate, and principal substance may be applied to the surface having the gating agent applied thereto, whereupon the portions of the principal substance that contact the jetted gating agent may be converted to a gel or a solid. Alternatively, the principal substance may be applied in an indiscriminate (i.e., non-selective) fashion to the plate and the gating agent may thereafter be selectively applied to portions of the plate that are not to be imaged (i.e., non-image areas), whereupon the principal substance in the jetted portions is converted to a gel or solid. Still further, a two (or more) component gating solution could be used wherein the components are individually selectively applied in succession where each is individually jettable, but which, when applied in the same location, result in a chemical or physical reaction (e.g., similarly or identically to an epoxy-type reaction) to promote advantageous gating characteristics. The principal substance, such as ink may be applied before or after one or more of the gating agent components are applied. In any of the foregoing examples, a substrate (such as a web of paper) may be imaged by the plate.
Another process variable is the substrate itself. In the case of a paper substrate, a conventional coated stock of appropriate size, weight, brightness, etc. may be used. One or more coatings, such as clay, may be applied thereto to delay/prevent absorption of principal substance and/or gating agent. In the case of other substrates, such as a printing blanket, a printing plate, a printing cylinder, a circuit board, a plastic sheet, a film, a textile or other sheet, a planar or curved surface of a wall, or other member, etc., the surface to which the principal substance is to be applied may be suitably prepared, processed, treated, machined, textured, or otherwise modified, if necessary or desirable, to aid in and/or block transfer of portions of the principal substance, as desired.
Still further, the nip pressure of the roller(s) and the compressibility characteristic of the roller(s) at which the principal substance is applied to the substrate may be varied to control image quality as well as the compressibility characteristic of the nip roller. Also, rolls or cylinders having a textured surface may be used to control the application of the principal substance to the substrate, as desired. Examples of cylinders having such a textured surface include a gravure cylinder having either a regular or irregular pattern of cells engraved thereon (by any known process e.g., diamond engraving, electron beam or laser engraving, acid etching, etc.) and an anilox roller used in conventional flexographic printing. In the latter case, an anilox roller with cells at a uniform or non-uniform line screening may be used. In specific examples, anilox rollers having resolutions between 600 lines per inch (lpi) and 3,500 lpi may be used, wherein the volume of each cell is related in some fashion to the drop volume of the ink jet heads that apply the gating agent. For example, the cell volume may be substantially equal to the drop volume of the particular ink jet head of the printing system. Alternatively, the cell volume may be selected so that gating agent rises slightly above the cylinder surface when a drop of gating agent is deposited into a cell (this may be desirable to aid in subsequent removal of the gating fluid upon contact with the paper or another substrate). Still further, or in addition, the volume of the drops of gating fluid could be adjusted to control the amount of ink transferred into each cell, thereby affecting grayscale. In the case of the HP ink jet head noted above, an anilox roller may be used having a resolution of 600 lpi to accommodate the 14 pl drop size emitted by such head. Alternatively, an anilox roller having a resolution greater than or lesser than 600 lpi may be used with the HP head such that each drop emitted by the head is deposited into multiple cells or occupies a portion of a cell, respectively. In any event (i.e., whether an anilox roller of particular resolution(s) is used or a gravure cylinder having cells of particular size(s) are used), gating agent is selectively jetted by the ink jet head(s) onto the textured roll or cylinder and such agent is retained thereon whereby lateral spreading of the gating agent is minimized/prevented by the constraining action of the walls forming the cells. Principal substance may thereafter be applied in a non-selective manner to the roll or cylinder, whereupon such principal substance flows to the non-wetted portions of the roll or cylinder. The roll or cylinder may then be used to transfer an image to the substrate, such as a web or sheet of paper, or an intermediate surface, as desired.
In these embodiments, the shape(s) and/or depths of the cells (the cell shapes may be the same or different on the roll or cylinder, as may the cell depths), may be optimized to the gating agent based on the surface energies of the gating agent and roll or cylinder surface and/or may be selected based upon another physical process parameter. Still further, one may use a roll or cylinder with cells arranged according to a random or pseudo-random screen, if desired.
A further approach using a gravure or anilox cylinder or roll differs from the foregoing in that all cells are initially indiscriminately filled with a first substance (preferably a fluid), prior to jetting, to a level where contact with paper or another further substrate would not draw the substance from the cells. Thereafter, selective application of a different or the same substance to one or more cell(s) increases the volume in such cell(s) in such a way as to enable contact with the paper or other substrate and selectively transfer at least some, if not a majority of the volume of the substance(s) in such cells. In these embodiments a small amount of jetted fluid can impact the transfer of a larger amount of cell volume, which may be required to achieve proper color density in a gravure-like application. This methodology also has the advantage in that more traditional gravure ink can be used to initially fill the cell.
These embodiments are illustrated in
In
In
In the preferred embodiment, the first substance is an ink and the second substance is a solvent for the ink. Alternatively, the two substances could be ink alone or any two similar or dissimilar materials that mix or do not mix on contact with one another. Still further, each drop of the second substance could be large enough to flow into multiple cells, if desired.
In a more general sense, the gating agent may be used to accomplish blocking or aiding the application of the principal substance by removing or blocking or applying the principal substance in image or non-image areas, removing an aiding agent in non-image areas, preventing the application of the principal substance in certain or all areas, changing the physical or chemical properties of the gating agent or principal substance (such as changing the viscosity or surface tension of the gating agent or principal substance) to affect the application of the gating agent or principal substance, any combination of the foregoing, or by any other suitable method.
The gating agent may be, in a further embodiment, a blocking agent that may be disposed on a surface to increase the attractive forces of the principal substance in non-image areas of the surface, wherein the attractive forces between the principal substance and the blocking agent on the surface are greater than the attractive forces between the principal substance and the substrate, thereby blocking the application of the principal substance to the substrate in non-image areas. In another instance, the blocking agent may be applied to the surface to decrease the attractive forces between the principal substance and the surface in non-image areas after an application of the principal substance to the surface to aid in cleaning the surface before additional principal substance is applied thereto. In other embodiments, the gating agent may be lipophilic or hydrophilic, depending on whether the desired result is for the gating agent to increase or decrease the attractive forces of the principal substance to the surface.
In yet other embodiments, the amount of the principal substance applied to the substrate may vary through use of a gating agent in the form of a barrier or a blocking agent with barrier qualities. In such embodiments, the application of the principal substance to the substrate may be blocked either completely or partially, so that the principal substance may be applied in intermediate levels to the substrate, as the barrier or the blocking agent with barrier qualities allows, effectuating a density gradient of the principal substance on the substrate in accordance with desired intermediate levels of principal substance application.
Further embodiments include applying the blocking agent to a surface before or after the principal substance is applied thereto and, optionally, selectively applying blocking agent to a substrate, and then imaging the substrate with the surface. For example, the blocking agent may include a material dispersed within it that is resistant to affinity with the particular principal substance. The blocking agent may then be applied to the surface and/or the substrate in non-image areas, with the material dispersed within the blocking agent being absorbed into and/or received and retained on the surface and/or on or in the substrate. Thereafter, when the surface is passed adjacent the substrate, the principal substance is transferred to the substrate only in those areas that do not contain the blocking agent, as the material dispersed within the blocking agent resists the application of the principal substance to the non-image areas.
Another alternate embodiment comprehends multiple applications of a blocking agent on or near a surface. In one instance, the blocking agent may be a copolymer with hydrophilic and lipophilic components, where the hydrophilic component tends to establish a bond with the surface and the lipophilic component tends to establish a bond with the principal substance. Regardless of the composition of the blocking agent, the blocking agent is selectively applied to the surface only in the non-image areas. The principal substance may then be applied indiscriminately to the surface, such that the principal substance is transferred to areas only where the blocking agent has not been applied. In an alternate embodiment, the principal substance is selectively applied in the areas between the patterned application of the blocking agent. A second application of the same or differently composed blocking agent may then be applied to the surface and/or the further substrate to be imaged, such as a paper web, by the surface. The second application of the blocking agent may be selectively applied in a discriminate fashion either over the first application of the blocking agent and/or the principal substance on the surface or to the further substrate. For example, a determination may be made where potential areas of quality degradation has or might occur (e.g., edges, borders, transitions in image density, or highlight areas) in the application of the principal substance to the substrate. Such a second application of the blocking agent could clear up the edges, borders, transition areas, or highlight areas of the principal substance as it is applied to a substrate, creating a more precise, or sharper, application of the principal substance. In the case of highlight areas, one might selectively apply gating agent to the surface before and to the surface and/or substrate after application of principal substance, such that the resultant combination produces a highlight imaged area that is accurately reproduced. One might apply smaller and/or fewer dots of gating agent to the surface during the initial application of the gating agent to prevent merger or interaction of closely-spaced dots of gating agent. Thereafter, the second application of gating agent may be selectively applied, preferably to the further substrate, in some or all of the areas of the further substrate where no principal substance is to be applied. This can promote more accurate transfer of principal substance in areas to be lightly covered with principal substance. This method of initially applying smaller and/or fewer dots of gating agent could also be used in areas other than areas to be lightly covered with principal substance.
One embodiment of the method of applying smaller and/or fewer dots of gating agent is implemented by the printing deck 2000 of
Alternatively, the applicators 2004 and 2010 may be arranged in a non-aligned configuration as seen in
In the embodiments of
Alternatively, or in addition, an aiding agent may be used that contains a material dispersed within it for promoting affinity to the principal substance. The aiding agent may be applied to the surface in image areas, with the material dispersed within the aiding agent being absorbed into and/or received and retained on the surface. The surface is passed adjacent a further surface having the principal substance disposed thereon and the principal substance is drawn to the first-named surface only in those areas that contain the aiding agent. Any of the embodiments of
Further embodiments include dilution of the principal substance with a relatively low viscosity fluid to decrease the attractive forces of the principal substance to a surface, or addition of a relatively high viscosity fluid to increase the attractive forces of the principal substance to a surface. Decreasing the attractive forces of the principal substance decreases the binding strength between the principal substance and a surface to which it is bound. A decreased binding strength aids in the release of the principal substance from the surface. Alternately, increasing the attractive forces increases the binding strength between the principal substance and the surface to which it is applied. An increased binding strength impedes the release of the principal substance from the surface to a substrate during subsequent image transfer.
In other embodiments, electrostatic charge is used to aid in application of the principal substance to the substrate. For example, an impression cylinder 4000 may have an electrostatic charge 4002 applied thereto, as shown in
A further embodiment as shown in
Transfer of the ink 4004 from the blanket cylinder 4006 may be aided by using a silicone cylinder 4023 to create a “waterless” system, as described previously herein. The cylinder 4023 may have a silicone surface that is entirely oleophobic. As known in the art of waterless lithography, such cylinders may be developed (e.g., etched) such that portions of a surface of the cylinder become oleophilic. Because the silicone is naturally oleophobic, there is no need to wet the cylinder before applying ink to the cylinder surface.
The embodiments described in
As previously described herein, there may be a wide variety of methods to apply a principal substance, for example an ink, to a substrate, for example a web of paper. Each method may include one or more intermediate steps as illustrated by the embodiment described in regard to
If a plate cylinder is utilized in an intermediate step to apply ink to the blanket cylinder 4006, the plate cylinder may have ink 4004 applied thereto from an ink train 4008. The plate cylinder may also have a silicone surface that is entirely oleophobic and that therefore does not require wetting before the application of ink thereto.
In addition, another embodiment may use an electrostatically charged blocking agent. The principal substance may be disposed on a surface and covered by a blocking agent in non-image areas, charged either positively or negatively, but the same polarity as the charge applied to a substrate. As the surface is brought adjacent the substrate, portions of the principal substance covered by the blocking agent will be repelled away from the substrate and remain on the surface, while the portions of the principal substance not covered by the blocking agent will be applied to the substrate, creating a desired image on the substrate.
In yet other embodiments, the gating agent(s) used to control application of the principal substance to the substrate may be combinations of blocking and aiding agents. In one example, the principal substance is disposed on a surface and is covered in non-image areas by a blocking agent that blocks application of the principal substance to the substrate. In image areas, the principal substance is covered by an aiding agent that tends to establish a bond with the principal substance to aid in application onto the substrate. Alternately, the gating agent(s) may be disposed on the surface and covered by the principal substance. In one example, a lipophilic blocking agent is selectively disposed on non-image areas of the surface and a hydrophilic aiding agent is selectively disposed on image areas of the surface. The principal substance is then disposed on top of the layer created by both gating agents. The layer of both gating agents having a consistent height on the surface may prevent migration between the principal substance and the aiding agent. As the surface is moved adjacent the substrate, the blocking agent keeps the principal substance from being applied to the substrate, while the aiding agent allows application of the principal substance to the substrate. In any event, the constituents(s) that are used during a production sequence (including the gating agent(s) and other constituents) should be compatible in the sense that undesirable results and consequences (such as the production of undesirable compounds or conditions) are avoided.
In alternate embodiments, the surface may be a lithographic plate, cylinder, or the like having a portion that may be used for controlling application of the principal substance to the substrate by applying variable configurations of the principal substance to the substrate. In such embodiments, variable symbology, encoding, addressing, numbering, or any other variable tagging technique may be utilized in the portion of the surface reserved for controlling application of the principal substance. The principal substance is first disposed on the surface indiscriminately. Before the substrate is passed near the surface for application of the principal substance, a blocking agent is selectively applied to the substrate in an area where the reserved portion of the surface will subsequently be moved adjacent the substrate so as to allow the desired configuration, or image, of the principal substance to be applied thereto. In a more general embodiment, the substrate may be brought adjacent one or more than one surface having similar or differing principal substances disposed thereon, wherein blocking and/or aiding agents are selectively transferred to the substrate from the surfaces in the reserved portion. In one embodiment, a magnetic ink is transferred from one of these surfaces to the substrate (e.g., a paper web). One or more non-magnetic inks may be transferred from the same surface or from one or more additional surfaces. A gating agent may be used to either block or aid application of the magnetic ink to the paper web in a desired configuration in the reserved portion thereof using any of the techniques for using blocking and aiding agents described above. The result is a printed paper web having markings of magnetic ink (such as a MICR marking or other encoded information) that may be changed from impression-to-impression.
According to a still further embodiment, the gating agent is selectively applied to a receiver surface by one or more ink jet heads and attracts or blocks an intermediate fluid, such as traditional fountain solution, which is applied indiscriminately to the receiver surface but gated by the gating agent, such that the fountain solution adheres selectively to the receiver surface prior to application of ink thereto. In this embodiment, the gating solution is formulated to interact with and control the fountain solution, as opposed to controlling the ink. Additional embodiments may neutralize or compromise the fountain solution, or selectively enable removal thereof from the receiver surface. In more general terms, these embodiments comprehend the use of a selectively applied gating solution together with indiscriminately applied fountain solution and ink wherein the gating agent controls where the fountain solution is maintained.
Any of the aqueous jet systems as described above with respect to
One of the advantages of using the concepts for processing variable and static print jobs as have been described herein is the inherent speed associated with a conventional lithographic press. In fact, press speed compared to a conventional lithographic press is limited by the speed at which an image area can be created, which in turn depends upon the method of creation of the image area. Such methods have been described herein to include application of a gating agent to create the image area. The gating agent may be a lipophilic or hydrophilic solution, or some other solution that may have an electrostatic charge applied thereto. The gating agent may also be an electrostatic charge applied to a portion of a cylinder, as illustrated by the embodiment described in regard to
Ink jet cartridges eject droplets of ink by various methods depending on the type of cartridge, as discussed in detail hereinbefore. Each type of cartridge has a maximum frequency at which droplets may be generated for ejection. This maximum drop generation frequency for a single ink jet cartridge may limit the speed at which the press may be operated. Multiple ink jet cartridges may be used to overcome this frequency limitation. For example, two ink jet cartridges may be used to eject droplets out of phase with one another to attain double the drop generation frequency of a single cartridge, and therefore double the press speed. Following this logic, three or more ink jet cartridges may be used to eject droplets out of phase with one another to further increase the press speed. More generally, multiple ink jet cartridges may be positionally staggered perpendicular to or at any other angle relative to the direction of travel of a receiving surface to increase resolution of the ejected droplets. A larger diameter target substrate in the form of an imaging blanket or cylinder may be used onto which the gating agent is applied, wherein the increased diameter permits multiple ink jet heads to be arrayed adjacent thereto. Ink jet heads having multiple channels may be used, wherein each channel is normally intended to apply a particular color of ink to a substrate. In such a case the ink jet head can be used to supply gating agent(s) via each channel (either at the same times or at different times during a production sequence) so that higher resolution, higher run speeds, or another desirable result can be achieved.
For most operating conditions wherein an ink jet cartridge may be utilized, the ejection of a droplet from the cartridge is effectively an instantaneous event that produces a spot of ink of predetermined size on a target substrate. In reality, the ejection of a droplet from an ink jet cartridge is not an instantaneous event, but is in fact a transient event, having a beginning, a middle, and an end. If a target substrate is moving at a high speed, the ink droplet may strike the substrate to form a spot of ink having a tail trailing the spot in a direction opposite to the direction of travel of the substrate. This phenomenon, known as tailing, is a direct result of the transient nature of the droplet generation. Tailing at high press speeds may limit the effective speed of the press due to print quality concerns. However, certain gating agents, when used with particular ink jet cartridges may inhibit or alleviate the tailing of the ejected droplets, thereby removing this effect as a limiting factor on maximum press speed. Also, the positioning of the ink jet heads relative to the target substrate may reduce tailing. For example, the ink jet heads may be disposed at an angle relative to the target substrate such that drops travel along a path that is not along a radius of the target substrate.
Because the generation of an electrostatic charge on one or more of the press cylinders may also limit the speed of operation of a press, it is contemplated that press cylinders may be charged internally using a known high speed process. For example, a laser or light emitting diode (LED) array may be embedded within a press cylinder fabricated of known materials, including, for example selenium, to selectively charge or discharge selected portions of the cylinder, as discussed in regard to
The utility of the concepts described herein is not limited only to variable jobs, wherein, for example, successive different pages of a book are printed. The concepts are also useful for short run static jobs, which would be much more expensive and time consuming to produce using traditional fixed plate lithographic methods. Traditionally, each short run job would require a plate to be produced bearing the short run image areas, and when the short run is finished, the press would have to be stopped to have the plate changed to a different plate to be used in the next short run. The methods of creating an image area as discussed herein allow the press to be run continuously while having the capacity to update the image area at any point during the run.
The ability to update an image area without stopping the press also facilitates another capability that is impossible using a traditional press, such as an offset or gravure press. The embodiments disclosed herein permit pages of different sizes to be imaged by a cylinder, even pages longer than the circumference of the imaging cylinder. In traditional offset page sizes are restricted depending on the size of the cylinder, i.e., based on the integral number of pages that can fit about the circumference of the cylinder. That gives a set size page, which can reduced by trimming and creating waste to some extent, but essentially a press is purchased and used for certain size work. In the present embodiments, on the other hand, the variable length cutoff capability overcomes this limitation. This ability is useful for sequentially producing books of different sizes, for example, in postal sort order, so that postal discounts can be obtained. In the case of a printed image which is to be longer than the circumference of the cylinder, a leading portion of the image that has already been printed is updated while a trailing portion of the image is printing. This continuous updating/printing methodology may be used to print long banners or strips of an exceedingly large print area that might otherwise require a much larger press apparatus.
Alternatively, multiple pages can be resized on-the-fly to be printed by a single cylinder during a single impression. An example of where this might be useful is where larger images are to be reduced in size and printed together on a single page, which may be enlightening for side-by-side comparisons or contrasts of the images.
If ink and an associated gating agent are entirely transferred from the cylinder to the paper in such a continuous variable cut-off application, then no intermediate cleaning of the leading portion is required because application of the image onto the paper concurrently cleans the cylinder. However, if a method is employed wherein the cylinder does require intermediate cleaning, a cleaning solution engineered for that purpose may be selectively applied to the cylinder to clean residual matter from the leading portion of the image area before additional imaging is applied thereto. The cleaning solution may be sprayed uniformly over the leading portion of the image area as it comes around on the cylinder. However, it is contemplated that a cleaning solution that is applied only where desired or needed is advantageous because such precise application results in less residual cleaning solution to collect. To facilitate precise guidance, the cleaning solution may have an electrostatic charge applied thereto interacts with an electrostatic charge applied to the cylinder. The cylinder may be electrostatically charged from within, for example by a laser or LED array as described previously. Internal application of the electrostatic charge as described may target a desired portion of the cylinder and may be accomplished as quickly as possible so as to have no effect on the press speed.
In a still alternate embodiment, an imaging element, such as a plate, cylinder, blanket, etc. could be selectively cleaned between imaging cycles thereof based upon the differences between successive images. This could be accomplished by the selective application of cleaning solution to the imaging element using one or more ink jet heads (which may be the same ink jet heads that apply gating agent to the imaging element or one or more separate heads) during the interval between application of successive images only to those areas where image changes are to occur.
In a typical cyan, magenta, yellow, and key (CMYK) printing press, each of the four colored inks is applied to the image individually to build the overall image. This traditional methodology is applicable to the concept of a continuously updating image area as well. The continuously updated image may just be repeated once for each applied colored ink. Therefore, as in a traditional system, it may be important to precisely align the application of each color with respect to the previous color to provide sharpness and inhibit a blurred image. Alignment of each image area of a successive color may be facilitated by electronic registration of the image areas. Such a system operates by a registration mark being applied to a substrate, such as a web of paper, just ahead of or possibly as part of an image area in one or more parts of the image area. An electronic sensor disposed above the web of paper may optically or otherwise sense the registration mark as it passes thereunder. The timing control of when to update the image area may be matched to the position of the web of paper on each of the presses as sensed by the sensors. This methodology eliminates the need for servo motors, wherein the exact position of each motor is known and coordinated. Instead, it is the precise position of the web of paper itself that is tracked by the electronic registration marks and sensors. Further, such a method may be used to account for stretching of webs of paper that may invariably occur when inks and other fluids are applied to the paper. A system that utilizes multiple registration marks both within and preceding an image area may be used to account for stretching to very high levels of accuracy that may only be limited by the number and spacing of the registration marks or accuracy limitations inherent to creation of the image area.
If desired, the above-described registration methodology may be replaced or augmented by a registration methodology that uses other sensors, devices, controlling apparatus, etc.
Ink jet head(s) or cartridge(s) may be positioned depending on the desired functionality thereof in a number of positions relative to components of the press. As described previously, one or more ink jet cartridges may be positioned to apply a gating agent ejected therefrom onto a plate cylinder, a blanket cylinder, a pre-plate cylinder, or onto the web of paper. Further, one or more ink jet cartridges may apply a cleaning solution to one or more image areas of the plate cylinders or to the blanket cylinder. The ink jet cartridge(s) may further be positioned relative to each of the components, for example, above or below each component, or ahead of or behind each component relative to the path that the web of paper takes through the press.
An ink jet cartridge employed to clean an image area may be positioned following an ink train. The ink jet cartridge may remain idle so long as the image area is static. However, between application of a last impression of a first static job and application of a first impression of a second job, the ink jet cartridge applies a cleaning solution to the image area. This application of the cleaning solution assists the process of loosening any latent image ink of the first job so that a cleaning mechanism, for example the cleaning mechanism 212 as described in regard to
Referring to
In a second alternate approach 5013, following the application of the last impression of a first static job from the cylinder 5002, the ink jet cartridge 5006 applies the blocking agent 5008 to form the negative image 5010 on the cylinder 5002 to create the new image area 5012. The ink 5004 is then applied in the new image area 5012, followed by a second layer 5014 of the blocking agent 5008 selectively applied to the cylinder 5002 to ensure coverage of the latent image 5000 until the latent image 5000 is entirely removed.
Removal of the latent image 5000 as described above may proceed concurrently with the continued operation of the press utilizing either of the two alternate approaches just described. On each rotation of the cylinder, the latent image area may have the cleaning solution precisely applied thereto and the cleaning mechanism 212 may brush and wipe the latent image area, followed by application of the ink 5004 and the blocking agent 5008 as in the first alternate approach, or application of the blocking agent 5008, ink 5004, and a second layer 5014 of the blocking agent 5008, as in the second alternate approach. Complete removal of the latent image 5000 may require several rotations of the cylinder 5002. Although applying the cleaning solution to the image area may be more effective to completely eliminate the ink in the latent image area in a timely fashion, each of the alternative approaches may allow the press to produce a high quality image of the second job immediately by covering the latent image 5000 from the first job.
A still further option is to modulate/control the temperature of one or more process parameters. For example, one might elevate the temperature of the gating agent upon application thereof to a surface to improve adherence and facilitate dispensing thereof. Alternatively, or in addition, the surface may initially be heated during application of gating agent to control adhesion, drop shape/size, and the like, and/or the surface may be chilled (or, in the case of other constituents, heated) at some point in the process once the gating agent is applied thereto so that the viscosity of the gating agent is increased, thereby reducing spread of the gating agent into non-wetted areas.
One could further use multiple different liquids dispensed by separate inkjet devices that, when applied together, create a gating agent that has improved adherence and/or viscosity and/or other desirable characteristic. The liquids may be applied at the different or same temperatures, pressures, flow rates, etc.
Yet another embodiment comprehends the use of two or more arrays or ink jet heads for selectively applying gating agent alone, or for selectively applying gating solution to one or more areas of a surface and, optionally, ink to one or more remaining areas of the surface, wherein one or more of the arrays can be independently removed and switched over while the press is running, or, reconfigured (in terms of position) for the next succeeding job (e.g., where regional customization is required).
Due to variations in ink tack from print unit to print unit, one may undertake a successive modification of gating agent characteristics from unit to unit to effectively optimize ink transfer by each unit.
If desired, the gating agent may be applied to a roll or cylinder of small diameter wherein the speed of the roll is significantly higher than in a conventional process. This high rotational speed forces applied droplets to extend outwardly due to centripetal forces at the surface of the small roller. This effect, in turn, reduces the contact pressure required to transfer liquid to another surface, such as a paper web, thereby minimizing spread of gating solution into non-wetted areas and permitting reduction in spot size. Thus, quality and resolution may be improved.
Different physical angles for screening may be used, e.g., different angles relative to vertical may be employed to affect the shape of dots of the gating agent. Further, a delay may be electronically interposed in the application of drops of gating agent to simulate screening, and/or an offset alignment may be used to eliminate overlap. The distance of the ink jet heads from the surface onto which gating agent is to be applied may be varied to vary dot sizes for different colors.
One could direct air from an air source to a surface on which gating agent is applied to change drop structure to reduce tailing, reduce film thickness, or interact with liquid. In this case, one could employ a liquid gating agent that is sensitive to air and supply same in an enclosed environment, such that air reacts with it after application to promote a favorable effect.
As noted above, one could apply liquid gating agent to a plate and thereafter spray diffuse particles to adhere to moistened area, and then transfer to paper. As contrasted with the embodiment described above, the gating agent and the diffuse particles need not be limited to powdered colorant and solvent, but may be any liquid and any particles (or any substances of any type, whether solid or fluidic).
An optional process step comprehends the periodic or aperiodic cleaning of system components, either in-line or off-line. Still further, ink emulsification, color density, or any other feedback parameter may be monitored to determine the volume of gating agent to spray to maintain color quality, and when to change ink supply. One or more process parameters may be sensed and used to control the distance of the ink jet head(s) from a roll, plate, or other substrate so that dot size is controlled.
Still further, one may utilize an intermediate roll with a pitted surface onto which the gating agent is applied to reduce spreading prior of same to application thereof to a blanket. Alternatively, or in addition, the ink jet heads may apply gating agent (and, optionally, ink) to a large diameter roll that rotates at a slow rotational speed as compared with conventional printing processes so that a large number of ink jet heads can be placed adjacent the roll. As a still further alternative, gating agent may be selectively applied by ink jet heads to a plate having through holes and a negative pressure may be developed behind the plate to reduce droplet size. More generally, negative and/or positive pressures may be used. If the cylinder is chambered, or has an independent structure therein that is chambered, a negative pressure can be developed in a first chamber that serves to reduce droplet size. The air flow that is used to develop the negative air pressure may be at a positive pressure in a second chamber, and such positive pressure may be used to release drops for application to or cleaning of the cylinder. Pressures can be adjusted as necessary or desirable to optimize the interaction (i.e., application and/or release) of the gating agent with the receiver surface and/or the interaction of the gating agent with the paper.
Yet another modification involves the use of a phase change material to build up a printing surface. One example involves the use of one or more curable and removable materials as the gating agent. For example, a UV curable gating agent in liquid form may be deposited on a plate and is thereafter subjected to UV light. The gating agent hardens, and ink is thereafter non-selectively applied to the plate. The ink is either attracted to or repelled by the hardened gating agent, and the resulting image is applied to substrate, such as a paper web. The gating agent and ink (if any) are then removed from the plate in preparation for subsequent imaging. This removal may be effected by washing any remaining ink from the plate, reversing the phase of the gating agent to a liquid, and/or removing the agent and any ink by washing, or the like.
If desired, gating agent may be applied indiscriminately over an entire imaging surface wherein the gating agent is responsive to the application of energy thereto to either activate or deactivate the gating agent. For example, the distributed gating agent may be selectively exposed to a source of UV, IR, or other non-visible wavelength energy or light emanated by a laser to create ink receptive or ink repellant areas in those portions of the surface exposed to such energy. Ink may then be indiscriminately applied to the surface and the ink may migrate to the exposed or non-exposed portions. The surface may then be used to image a further substrate, as in previous embodiments.
One could optimize the inter-imaging cleaning process by using a paper or other substrate type that minimizes residue on the imaging surface once the image has been printed or otherwise transferred. A still further embodiment comprehends the use of two or more imaging elements in the form of cylinders, plates, blankets, etc., for each ink to be applied to a further substrate wherein one or more, but fewer than all, of the imaging cylinders, plates, blankets, etc. are in use at any particular time of a production sequence and the remaining imaging elements are being cleaned. At a later point in the production sequence a different subset of the imaging elements may be in use while remaining imaging elements are being cleaned. This arrangement may permit higher press speeds to be employed.
In another embodiment, an aqueous jet system may print or jet an aqueous solution or other composition that has a multifunctional potential onto a pattern substrate. In one embodiment, for example, the composition may have a bifunctional potential, though any number of functionalities are contemplated herein. For example, the multifunctional composition may include one or more compounds each having a multifunctional potential or a plurality of compounds each having monofunctional potentials. A functional potential may include, for example, a function portion of a compound that may be attributable to a specific chemical moiety and/or structural region of the compound that confers attachment and/or repellant properties to the compound, such as, for example, a hydrophilic region, a lipophilic region, a receptor/recognition region (for example, a paratope), an ionic region, and others known in the art. In the present embodiment, one functionality confers attachment capabilities to the pattern substrate, and a second confers attachment properties to one or more principal substances that may be applied thereto.
In another embodiment, a multifunctional composition may include more than one multifunctional compound where each species of multifunctional compound has at least one functionality in common with the other multifunctional compounds and at least one functionality that differs from the other multifunctional compounds. In this example, a first multifunctional compound and a second multifunctional compound may each be printed onto a similar pattern substrate though the second functionalities of the first multifunctional compound and the second multifunctional compounds may have different specificities for a principal substance that can be attached to either the first or the second multifunctional compound, assuming the principal substance only reacts with one type of functionality. In another embodiment, compounds having monofunctional potentials may interact to form complexes having multifunctionality similar to that of single multifunctional compounds. In this embodiment, the monofunctional compounds may be included in a single composition that is deposited on the pattern substrate at one time, included in separate compositions deposited simultaneously, or may be contained in separate compositions that are deposited on the pattern substrate sequentially.
One example of a multifunctional compound contemplated herein includes a compound having one functionality that may be hydrophilic and a second functionality that may be lipophilic. The multifunctional composition may be jetted using in a desired pattern onto a substrate having either hydrophilic or a lipophilic surface, whereby like functionalities amongst the surface and the composition would associate to attach the composition to the surface and the opposite functionality of the composition would be repelled from the surface to render a pattern of the composition attached thereon.
A second composition, for example, the principal substance, having a like functionality (for example, hydrophilic or lipophilic) or otherwise attracted selectively to the second functionality of the multifunctional composition, which is not attached to the surface, and that is repulsed from or otherwise not attachable to the exposed surface of the substrate may be added to the surface by jetting, dipping, spraying, brushing, rolling, or any other manner known to a skilled artisan. Addition of the principal substance may render a pattern of the principal substance corresponding to that of the multifunctional composition, such that the principal substance is only attached to the surface via the second functionality of the multifunctional composition. It is further contemplated that after the application of the principal substance, one or more additional steps may be performed, including, for example a cleaning step, to ensure regiospecific attachment of the principal substance only to the second functionality of the multifunctional composition. Another contemplated step similar to the cleaning step includes a sterilization step. The principal substance may then be transferred to a second substrate, including, for example, an intermediate roller from which an image will be transferred to the print medium, or directly to the print medium to render the desired print image in a highly accurate and clean manner. In this way, selected patterns may be jetted onto a substrate using a multifunctional composition to which a principal substance is subsequently attached that then may be transferred to and immobilized permanently or transiently on a print medium.
Examples of multifunctional compounds contemplated herein include polymers, having at least one hydrophilic portion and at least one lipophilic portion, such as a poloxamer or acetylenediol ethoxylated. The poloxamer suitable for use can be represented by the formula HO(CH2CH2O)x(CH2CHCH3O)y(CH2CH2O)zH wherein x, y and z represent integers from the range from 2 to 130, especially from 15 to 100, and x and z are identical but chosen independently of y. Among these, there can be used poloxamer 188, wherein x=75, y=30 and z=75, which is obtainable under the trade name Lutrol® F 68 (alternatively Pluronic® F-68) from BASF, poloxamer 185 wherein x=19, y=30 and z=19 (Lubrajel® WA from ISP), poloxamer 235 wherein x=27, y=39 and z=27 (Pluronic® F-85 from BASF) and/or poloxamer 238 wherein x=97, y=39 and z=97 (Pluronic® F-88 from BASF). Another particular surfactant of this type is the block copolymer poly(ethyleneoxide)-poly(propyleneoxide)-poly(ethyleneoxide) known as Pluronic® F-123 from BASF. In addition, a triblock copolymer known commercially as Pluronic® F-127 (poloxamer 407) from BASF for which x=106, y=70, and z=106 may be used. Additionally, poloxamer 101, 108, 124, 181, 182, 184, 217, 231, 234, 237, 282, 288, 331, 333, 334, 335, 338, 401, 402, and 403, respectively can be included in the gating agent, to name a few. The acetylenediol ethoxylated suitable for use include 3,5-dimethyl-1-hexyn-3-ol (Air Products' Surfynol® 61), and/or 2,4,7,9-tetra-methyl-5-decyne-4,7-diol (Air Products' Surfynol® 104), among others. Other surfactants suitable for use include hexadecyl trimethylammonium bromide (CTAB), polyoxyalkylene ether, poly(oxyethylene)cetyl ether (e.g., Brij® 56 or Brij® 58 from Atlas Chemicals).
Additional examples include materials associated with the formation of self-assembled monolayers, such as alkylsiloxanes, fatty acids on oxidic materials, alkanethiolates, alkyl carboxylates, and the like. Other multifunctional compounds known to one skilled in the art are contemplated in the present disclosure. Further, multifunctional solutions contemplated herein may include, in addition to the one or more multifunctional compounds, for example, water, a water-soluble organic, or a combination thereof. Suitable water-soluble organic components include: alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, or tert-butyl alcohol; amides, such as dimethylformamide or dimethylacetamide; carboxylic acids; esters, such as ethyl acetate, ethyl lactate, and ethylene carbonate; ethers, such as tetrahydrofuran or dioxane; glycerin; glycols; glycol esters; glycol ethers; ketones, such as acetone, diacetone, or methyl ethyl ketone; lactams, such as N-isopropyl caprolactam or N-ethyl valerolactam; lactones, such as butyrolactone; organosulfides; sulfones, such as dimethylsulfone; organosulfoxides, such as dimethyl sulfoxide or tetramethylene sulfoxide; and derivatives thereof and mixtures thereof. Additional contemplated components in the multifunctional solutions include a solvent, a preservative, a viscosity modifier, a colorant, a scent, a surfactant, a polymer, a foaming agent, a salt, an inorganic compound, an organic compound, water, a pH modifier, and any combination thereof. Examples of principal substances include, for example, lithographic inks, dyes, proteins (for example, antibodies, enzymes, prions, nucleic acids (for example, DNA and/or RNA oligonucleotides), small molecules (for example, inorganic and/or organic molecules), biological samples (for example, cell and/or viral lysates and fractions thereof), pharmaceuticals (including antibiotics and/or other drugs, and salts, precursors, and prodrugs thereof), cells (for example, prokaryotic, eubacterial, and/or eukaryotic cells), and metals (for example, silicon oxides, conductive metals and oxides thereof). Print media contemplated include paper, glass, nitrocellulose, textiles, woven materials, metal, plastic, films, gels, and combinations thereof.
Illustratively, one example of an apparatus that may be employed to implement the current embodiment is illustrated in
Operation of the printing deck 6100 is similar to other embodiments described herein. For example, a multifunctional composition is applied by the aqueous jet system 6114 onto the pattern surface 6104 of the pattern surface cylinder 6106. A principal substance is applied subsequently to the pattern surface 6104 via the application system 6102. As the pattern surface 6104 meets the surface of the blanket cylinder 6108, the principal substance is transferred thereto to be further carried thereon until deposited onto a substrate 6116. It is further contemplated that the apparatus may exclude blanket cylinder 6108 and thus the principal substance would be directly transferred from the pattern surface 6104 to the substrate 6116. Alternatively, additional rollers as desired may be added that may include, for example, additional aqueous jet systems 6114, application systems 6102, and cleaning system 6112.
Additional variations associated with other embodiments disclosed herein are equally applicable in the current embodiment as appropriate for the desired outcome. Additional apparatus configurations (not shown) are contemplated herein that enable high speed, highly accurate, selective deposition of one or more principal substances using combined multifunctional compositions and ink jet technologies. In this way, products including, for example, diagnostic tests, electric chips, oligonucleotide arrays, protein arrays, cell arrays, chemical arrays, drug arrays, detection systems, printed materials (for example, literature), and the like, and any combination thereof may be produced.
The jet system 6114 of
An application system 7000 that may be used to implement any of the methods disclosed herein is generally shown in
A further aspect of the embodiments disclosed herein is that localized color correction can be undertaken at any portion(s) of an image. The resolution of such color correction is not limited to the location of the print area that could be impacted by individual ink keys on a traditional offset press; rather, the color correction can be undertaken at the resolution at which the gating agent is applied to the receiver surface. Further, color correction can be applied to a portion of the image or the entire image. Still further, it may be desirable to modify the gating agent applied by one applicator before application of a further substance by a further applicator. For example, in a multi-color printing process, a first gating agent that blocks or aids transfer of a first ink to a paper web and which is applied by a first printing deck may be deactivated before the paper web reaches a second printing unit where a second gating agent (which may be same as or different than the first gating agent) and second ink may be applied to the web. This deactivation may be undertaken by any suitable means, such as the selective application of a deactivating chemical using ink jet heads after the first ink has been transferred to the web. Alternatively, the gating agent(s) may be modified in another fashion using any other apparatus so that a beneficial characteristic of the gating agent(s) remains on the further substrate.
In yet another alternative embodiment, the gating agent may control absorption of a substance into a substrate. For example, a gating agent may limit or otherwise optimize absorption of a gravure ink into a paper web to improve color reproduction. The gating agent may be applied to the paper web, as in the preceding embodiments, by any suitable means, such as one or more ink jet heads.
If desired, one may adapt the methods disclosed herein to permit build up of multiple successive layers of principal substance and gating agent on a receiver surface and application of such multiple layers to a further surface. Also, if the gating agent(s) that are applied to the substrate are colored (i.e., not completely colorless) one might take this fact into account when selecting ink type and/or amounts (i.e., the ink film thickness and/or ink amounts for the image as defined by the controller (i.e., RIP(s))) to use in a color reproduction process. Still further, gating agent may interact with applied principal substance to create a desired effect. For example, in a color printing process, the gating agent may combine with applied ink to modify ink color, as desired. Instead or in addition, gating agent applied to a substrate may react with other applied substance(s) to permit counterfeit detection, integrity checking, sequence checking, etc. In this case the gating agent may be applied before, after, and/or contemporaneously with the other applied substance(s).
Also if desired, more than one imaging element such as a plate, blanket, cylinder, etc. may be used to transfer an image and gating agent to a further surface, which, in turn, transfers the image and gating agent to a further substrate, such as a paper web. Still further, gating agent may be selectively applied alone or in combination with one or more other materials to an imaging element, which, in turn applies the gating agent and other material(s) to a further imaging element that receives the principal substance. The principal substance, gating agent, and other material(s) may be transferred to the substrate by the further imaging element or another imaging element disposed between the further imaging element and the substrate. For example, a silver conductive trace may be laid down first on a cylinder, followed a resistive material followed by a semiconductive material and the combination may then be applied directly or indirectly via another imaging element to a further substrate, such as a mylar film, a paper web, a circuit board, or the like.
In a specific application, the high speed variable printing systems and methods disclosed herein may be used in a number of lithographic applications. For example, the disclosed systems and methods may be ideal for high-quality one-to-one marketing applications, such as direct mailing, advertisements, statements, and bills. Other applications are also well-suited to the systems and methods disclosed herein, including the production of personalized books, periodicals, publications, posters, and displays. The high speed variable printing systems and methods disclosed herein may also facilitate post-processing (e.g., binding and finishing) of any of the aforementioned products.
It will be understood that the foregoing is only illustrative of the principles of the systems and methods disclosed herein, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of such systems and methods. For example, the order of some steps in the procedures that have been described are not critical and can be changed if desired. Also, various steps may be performed by various techniques.
The present disclosure is applicable in the printing arts, but also may be useful in other industries. More specifically, a gating agent is applied to a substrate to aid in determining the application of a principle substance in image or non-image areas.
Numerous modifications will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention and to teach the best mode of carrying out same. The exclusive rights to all modifications which come within the scope of the appended claims are reserved.
The present application is a continuation of U.S. patent application Ser. No. 12/229,129, which was filed on Aug. 20, 2008, which is a continuation-in-part of U.S. patent application Ser. Nos. 11/709,497, 11/709,428, 11/709,599, 11/709,429, 11/709,555, 11/709,396, all of which were filed on Feb. 21, 2007, and claims the benefit of provisional U.S. Patent Application Ser. Nos. 60/775,511 and 60/819,301 filed on Feb. 21, 2006, and Jul. 7, 2006, respectively. In addition the present application claims the benefit of provisional U.S. Patent Application Nos. 60/965,361, filed Aug. 20, 2007; 60/965,634, filed Aug. 21, 2007; 60/965,753, filed Aug. 22, 2007; 60/965,861, filed Aug. 23, 2007; 60/965,744, filed Aug. 22, 2007; and 60/965,743, filed Aug. 22, 2007. All of the above listed applications are hereby incorporated by reference herein in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 60775511 | Feb 2006 | US | |
| 60819301 | Jul 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12229129 | Aug 2008 | US |
| Child | 13099097 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11709497 | Feb 2007 | US |
| Child | 12229129 | US | |
| Parent | 11709428 | Feb 2007 | US |
| Child | 11709497 | US | |
| Parent | 11709599 | Feb 2007 | US |
| Child | 11709428 | US | |
| Parent | 11709429 | Feb 2007 | US |
| Child | 11709599 | US | |
| Parent | 11709555 | Feb 2007 | US |
| Child | 11709429 | US | |
| Parent | 11709396 | Feb 2007 | US |
| Child | 11709555 | US |
