INKING SYSTEM WITH PLUARLITY OF FOUNTAIN ROLLER ELEMENTS

An inking system is used to transfer a plurality of different inks to an anilox roller in a flexographic printing plate in a flexographic printing system. A fountain roller system including a plurality of coaxial fountain roller elements, each fountain roller element having an ink transfer zone with an ink transfer zone radius, wherein the ink transfer zone radii for the plurality of fountain roller elements are the same. A segmented ink tray includes a plurality of ink tray segments, wherein each fountain roller element is mounted within a corresponding ink tray segment. Each fountain roller element is adapted to receive ink from the corresponding ink tray segment and transfer the received ink to a corresponding zone of the anilox roller.

FIELD OF THE INVENTION

This invention pertains to the field of flexographic printing, and more particularly to inking systems for flexographic printing systems.

BACKGROUND OF THE INVENTION

Processing a web of media in a roll-to-roll fashion can be an advantageous and low-cost manufacturing approach for devices or other objects formed on the web of media. An example of a process that includes web transport through an additive printing system is roll-to-roll flexographic printing.

Co-planar wave guide circuits and touch screens are two examples of electrical devices that can be manufactured using a roll-to-roll additive flexographic printing process. For example, a capacitive touch screen includes a substantially transparent substrate which is provided with electrically conductive patterns that do not excessively impair the transparency—either because the conductors are made of a material, such as indium tin oxide, that is substantially transparent, or because the conductors are sufficiently narrow such that the transparency is provided by the comparatively large open areas not containing conductors. For capacitive touch screens having metallic conductors, it is advantageous for the features to be highly conductive but also very narrow. Capacitive touch screen sensor films are an example of an article having very fine features with improved electrical conductivity resulting from an additive printing system.

U.S. Patent Application Publication 2014/0295063 by Petcavich et al., which is incorporated herein by reference, discloses a method of manufacturing a capacitive touch sensor using a roll-to-roll process to print a conductor pattern on a flexible transparent dielectric substrate. A first conductor pattern is printed on a first side of the dielectric substrate using a first flexographic printing plate and is then cured. A second conductor pattern is printed on a second side of the dielectric substrate using a second flexographic printing plate and is then cured. The ink used to print the patterns includes a catalyst that acts as seed layer during a subsequent electroless plating process. The electrolessly-plated material (e.g., copper) provides the low resistivity in the narrow lines of the grid needed for excellent performance of the capacitive touch sensor. Petcavich et al. indicates that the line width of the flexographically-printed microwires can be 1 to 50 microns.

Flexography is a method of printing or pattern formation that is commonly used for high-volume printing runs. It is typically employed in a roll-to-roll format for printing on a variety of soft or easily deformed materials including, but not limited to, paper, paperboard stock, corrugated board, polymeric films, fabrics, metal foils, glass, glass-coated materials, flexible glass materials and laminates of multiple materials. Coarse surfaces and stretchable polymeric films are also economically printed using flexography.

Flexographic printing members are sometimes known as relief printing members, relief-containing printing plates, printing sleeves, or printing cylinders, and are provided with raised relief images (i.e., patterns of raised features) onto which ink is applied for application to a substrate. While the raised relief images are inked, the recessed relief “floor” should remain free of ink.

Although flexographic printing has conventionally been used in the past for the printing of images, more recent uses of flexographic printing have included functional printing of devices, such as touch screen sensor films, antennas, and other devices to be used in electronics or other industries. Such devices typically include electrically conductive patterns.

To improve the optical quality and reliability of the touch screen, it has been found to be preferable that the width of the grid lines be approximately 2 to 10 microns, and even more preferably to be 4 to 8 microns. In addition, in order to be compatible with high-volume roll-to-roll manufacturing processes, it is preferable for the roll of flexographically printed material to be electrolessly plated in a roll-to-roll electroless plating system. More conventionally, electroless plating is performed by immersing the item to be plated in a tank of plating solution. However, for high volume uniform plating of features on both sides of the web of substrate material, it is preferable to perform the electroless plating in a roll-to-roll electroless plating system.

Flexography is a form of rotary web letterpress, combining features of both letterpress and rotogravure printing, which uses relief plates comprised of flexible rubber or photopolymer plates and fast drying, low viscosity solvent, water-based or UV curable inks fed from an anilox roller. Traditionally, patterns for flexographic printing plates (also known as flexo-masters) are created by bitmap patterns, where one pixel in bitmap image correlates to a dot of the flexographic printing plate. For instance, pixels arranged in a straight line in the bitmap image will tum into a continuous straight line on the flexographic printing plate. For flexographic printing (also known as flexo-printing), a flexible printing plate with a relief image is usually wrapped around a cylinder and its relief image is inked using an anilox roller and the ink is transferred to a suitable printable medium.

Flexographic printing plates typically have a rubbery or elastomeric nature whose precise properties may be adjusted for each particular printable medium. In general, the flexographic printing plate may be prepared by exposing a UV sensitive polymer layer through a photomask, or using other preparation techniques.

Catalytic inks that are useful for fabricating electrical devices using processes such as that described in the aforementioned U.S. Patent Application Publication 2014/0295063 are typically quite expensive. Therefore, supplying a large quantity of ink to fill the ink tray a flexographic printing system can be quite costly, particularly when the fine patterns of conductors require only relatively small amounts of ink.

Commonly-assigned U.S. Pat. Nos. 11,135,832 and 11,072,165 describes a low-volume inking system for a flexographic printing system

Some applications of flexographic printing utilize inks that are transparent or have a very low optical density. Examples of such inks would include dielectric inks, adhesive inks and silver nanowire inks. Accordingly, in order to be able to align various patterns printed using different print modules, it is desirable to be able to use an opaque ink to print alignment marks (e.g., along the edges of the printed pattern). U.S. Pat. No. 9,807,871 discloses utilizing a plurality of inking systems to apply different inks to different zones of a printing roll so that fiducial marks can be printed with a high-contrast ink while other portions of the printed pattern can be printed with a low-contrast ink.

There remains a need for a simple inking system for a flexographic printing system that can be used to simultaneously provide different inks to different portions of a printing plate, particularly an inking system which operates with low volumes of the different inks.

SUMMARY OF THE INVENTION

The present invention represents an inking system for use in transferring a plurality of different inks to a flexographic printing plate in a flexographic printing system, including:an anilox roller with a cylindrical outer surface having a plurality of cells, the cells being indentations in the outer surface of the anilox roller configured to transfer ink to the flexographic printing plate;a fountain roller system including a plurality of coaxial fountain roller elements, each fountain roller element having an ink transfer zone with an ink transfer zone radius, wherein the ink transfer zone radii for the plurality of fountain roller elements are the same; anda segmented ink tray having a plurality of ink tray segments, wherein each fountain roller element is mounted within a corresponding ink tray segment;wherein the fountain roller elements are positioned such that the ink transfer zones contact corresponding zones of the cylindrical outer surface of the anilox roller; andwherein the ink transfer zone of each fountain roller element is adapted to receive ink from the corresponding ink tray segment and transfer the received ink to the corresponding zone of the anilox roller.

This invention has the advantage that different inks can be provided in different zones of the anilox roller.

In some embodiments a transparent ink can be supplied to one zone of the anilox roller and an opaque ink can be supplied to another zone of the anilox roller. This enables accurate alignment of the patterns printed using transparent ink.

It has the additional advantage that a smaller volume of ink can be used to supply ink to a particular ink transfer zone of the fountain roller.

It is to be understood that the attached drawings are for purposes of illustrating the concepts of the invention and may not be to scale. Identical reference numerals have been used, where possible, to designate identical features that are common to the figures.

DETAILED DESCRIPTION OF THE INVENTION

The present description will be directed in particular to elements forming part of, or cooperating more directly with, an apparatus in accordance with the present invention. It is to be understood that elements not specifically shown, labeled, or described can take various forms well known to those skilled in the art. It is to be understood that elements and components can be referred to in singular or plural form, as appropriate, without limiting the scope of the invention.

The invention is inclusive of combinations of the embodiments described herein. References to “a particular embodiment” and the like refer to features that are present in at least one embodiment of the invention. Separate references to “an embodiment” or “particular embodiments” or the like do not necessarily refer to the same embodiment or embodiments; however, such embodiments are not mutually exclusive, unless so indicated or as are readily apparent to one of skill in the art. It should be noted that, unless otherwise explicitly noted or required by context, the word “or” is used in this disclosure in a non-exclusive sense.

The example embodiments of the present invention are illustrated schematically and not necessarily to scale for the sake of clarity. One of ordinary skill in the art will be able to readily determine the specific size and interconnections of the elements of the example embodiments of the present invention.

References to upstream and downstream herein refer to direction of flow. Web media moves along a media path in a web advance direction from upstream to downstream. Similarly, fluids flow through a fluid line in a direction from upstream to downstream. In some instances, a fluid can flow in an opposite direction from the web advance direction. For clarification herein, upstream and downstream are meant to refer to the web motion unless otherwise noted.

FIG.1is a schematic side view of a flexographic printing system100that can be used in some embodiments of the invention for roll-to-roll printing of a catalytic ink or a conductive ink on both sides of a substrate150for subsequent electroless plating. Substrate150is fed as a web from supply roll102to take-up roll104through flexographic printing system100. Substrate150has a first side151and a second side152.

The flexographic printing system100includes two print modules120and140that are configured to print on the first side151of substrate150, as well as two print modules110and130that are configured to print on the second side152of substrate150. The web of substrate150travels overall in process direction105(left to right in the example ofFIG.1). However, various rollers106and107are used to locally change the direction of the web of substrate as needed for adjusting web tension, providing a buffer, and reversing the substrate150for printing on an opposite side. In particular, note that in print module120roller107serves to reverse the local direction of the web of substrate150so that it is moving substantially in a right-to-left direction.

Each of the print modules110,120,130,140includes some similar components including a respective plate cylinder111,121,131,141, on which is mounted a respective flexographic printing plate112,122,132,142, respectively. Each flexographic printing plate112,122,132,142has raised features113defining an image pattern to be printed on the substrate150. Each print module110,120,130,140also includes a respective impression cylinder114,124,134,144that is configured to force a side of the substrate150into contact with the corresponding flexographic printing plate112,122,132,142. Impression cylinders124and144of print modules120and140(for printing on first side151of substrate150) rotate counter-clockwise in the view shown inFIG.1, while impression cylinders114and134of print modules110and130(for printing on second side152of substrate150) rotate clockwise in this view.

Each print module110,120,130,140also includes a respective anilox roller115,125,135,145for providing ink to the corresponding flexographic printing plate112,122,132,142. As is well known in the printing industry, an anilox roller is a hard cylinder, usually constructed of a steel or aluminum core, having an outer surface containing millions of very fine dimples, known as cells. Ink is provided to the anilox roller by a tray or chambered reservoir (not shown). In some embodiments, some or all of the print modules110,120,130,140also include respective UV curing stations116,126,136,146for curing the printed ink on substrate150.

FIG.2is a schematic side view of a roll-to-roll electroless plating system200disclosed in commonly-assigned U.S. Patent Application Publication 2016/0168713 to Reuter et al., which is incorporated herein by reference. The electroless plating system200includes a tank230of plating solution210. Web of media250is fed by a web advance system along a web-transport path in an in-track direction205from a supply roll202to a take-up roll204. The web of media250is a substrate upon which electroless plating is to be performed. Drive roller206is positioned upstream of the plating solution210and drive roller207is positioned downstream of the plating solution210. Drive rollers206and207advance the web of media250from the supply roll202through the tank of plating solution210to the take-up roll204. Web-guiding rollers208are at least partially submerged in the plating solution210in the tank230and guide the web of media250along the web-transport path in the in-track direction205.

As the web of media250is advanced through the plating solution210in the tank230, a metallic plating substance such as copper, silver, gold, nickel or palladium is electrolessly plated from the plating solution210onto predetermined locations on one or both of a first surface251and a second surface252of the web of media250. As a result, the concentration of the metal or other components in the plating solution210in the tank230decreases and the plating solution210needs to be refreshed. To refresh the plating solution210, it is recirculated by pump240, and replenished plating solution215from a reservoir220is added under the control of controller242, which can include a valve (not shown). In the example shown inFIG.2, plating solution210is moved from tank230to pump240through a drain pipe232and is returned from pump240to tank230through a return pipe234. In order to remove particulates from plating solution210, a filter236can be included, typically downstream of the pump240.

FIG.3shows a close-up side view showing additional details of an exemplary embodiment of the print module110ofFIG.1. The illustrated configuration is equivalent to that disclosed in commonly-assigned U.S. Pat. No. 9,327,494 to G. Smith et al., entitled “Flexographic printing system with pivoting ink pan,” which is incorporated herein by reference. The print module110includes an ink pan160with a fountain roller161for providing ink to the anilox roller115. Fountain rollers161are sometimes referred to in the art as doctor rollers or metering rollers. Ink pan160includes a front wall162located nearer to impression cylinder114, a rear wall163located opposite front wall162and further away from impression cylinder114, and a floor164extending between the front wall162and the rear wall163. The ink pan160also includes two side walls (not shown inFIG.3) that extend between the front wall162and the rear wall163on opposite sides of the ink pan160and intersect the floor164. It should be noted that there may or may not be distinct boundaries between the front wall162, the rear wall163, the floor164and the side walls. In some embodiments, some or all of the boundaries between these surfaces can be joined using rounded boundaries that smoothly transition from one surface to the adjoining surface.

Fountain roller161is partially immersed in an ink165contained in ink pan160. Within the context of the present invention, the ink165can be any type of marking material, visible or invisible, to be deposited by the flexographic printing system100(FIG.1) on the substrate150. Fountain roller161is rotatably mounted on ink pan160. Ink pan160is pivotable about pivot axis166, preferably located near the front wall162.

A lip167extends from rear wall163. When an upward force F is applied to lip167as inFIG.3, ink pan160pivots upward about pivot axis166until fountain roller161contacts anilox roller115at contact point181. In the upwardly pivoted ink pan160the floor164tilts downward from rear wall163toward the front wall162so that fountain roller161is located near a lowest portion168of floor164. If upward force F is removed from lip167, ink pan160pivots downward under the influence of gravity so that fountain roller161is no longer in contact with anilox roller115.

A flexographic printing plate112(also sometimes called a flexographic master) is mounted on plate cylinder111. In an exemplary configuration, the flexographic printing plate112is a flexible plate that is wrapped almost entirely around plate cylinder111. Anilox roller115contacts raised features113on the flexographic printing plate112at contact point183. As plate cylinder111rotates counter-clockwise (in the view shown inFIG.3), both the anilox roller115and the impression cylinder114rotate clockwise, while the fountain roller161rotates counter-clockwise. Ink165that is transferred from the fountain roller161to the anilox roller115is transferred to the raised features113of the flexographic printing plate112and from there to second side152of substrate150that is pressed against flexographic printing plate112by impression cylinder114at contact point184.

In order to remove excess amounts of ink165from the patterned surface of anilox roller115a doctor blade180, which is mounted to the frame (not shown) of the printing system, contacts anilox roller115at contact point182. Contact point182is downstream of contact point181and is upstream of contact point183. For the configuration shown inFIG.3, in order to position doctor blade180to contact the anilox roller115downstream of contact point181where the fountain roller161contacts the anilox roller115, as well as upstream of contact point183where the anilox roller115contacts the raised features113on the flexographic printing plate112, doctor blade180is mounted on the printer system frame on a side of the anilox roller115that is opposite to the impression cylinder114.

After printing of ink on the substrate, it is cured using UV curing station116. In some embodiments, an imaging system117can be used to monitor line quality of the pattern printed on the substrate.

FIG.4, shows a conventional anilox roller115used in a flexographic printing process. The anilox roller115controls, in part, the volume of ink or other material transferred to a flexographic printing plate112(FIG.3) during the flexographic printing process. The anilox roller115includes a rigid cylinder310, which is typically constructed of steel, a carbon fiber composite, a carbon fiber composite covered with metal, chrome, or an aluminum core with steel. Roller mounts320are disposed on the distal ends311,312of cylinder310to secure and rotate the cylinder310during the flexographic printing process. Prior to depositing a surface coating330, the cylinder310is typically polished so that a longitudinal contact surface around cylinder310is smooth. The surface coating330is typically a hard ceramic, but can also be made of other materials such as chrome. After deposition, the surface coating330is preferably polished so that a longitudinal contact surface of surface coating330around cylinder310is smooth. The surface coating330is polished smooth because it is the contact surface of the cylinder.

An anilox roller pattern380including a plurality of cells340separated by walls350are patterned into the surface coating330as shown in close-up view360. The cells340do not extend into the cylinder310. Each cell340is a small indentation of a predetermined geometry in the surface coating330that holds and controls the amount of ink or other material (not shown) to be transferred to the flexographic printing plate112during the flexographic printing process. For the cell geometry depicted inFIG.4, a given cell340shares common walls350with six neighboring cells340. However, the number of common walls350shared by a given cell340may vary depending on the geometry of the cell340used in a particular application. Those skilled in the art will recognize that the cells340can be formed into the surface coating330with a variety of different processes such as etching processes and engraving process.

FIG.5, shows a cross-sectional view370through a surface of the anilox roller115ofFIG.4. The surface coating330(e.g., a ceramic coating) covers the longitudinal contact surface of cylinder310, and generally has a thickness335of at least 10 microns. A plurality of cells340are patterned into the surface coating330, but do not extend into cylinder310. The volume of ink or other material (not shown) held by a given cell340is typically measured in units of Billion Cubic Microns (“BCMs”). A cell340typically holds a volume of at least 0.5 BCM or more of ink or other material suitable for printing standard geometry lines and features. Each cell340typically has a cell size345of 10 microns or more.

In the depicted cross-section, a common wall350is formed between adjacent cells340patterned into surface coating330. The wall350is composed entirely of surface coating330and has a wall thickness355, which is typically related to the cell density. As the cell density increases, the thickness355of the wall350generally decreases. If the thickness355of wall350becomes too thin, it may break from contact with the doctor blade or the flexographic printing plate during the flexographic printing process or wear out over time from repeated use. If the wall350between adjacent cells340breaks, a substantially larger cell will be formed, resulting in inconsistent ink transfer volumes. Inconsistent ink transfer volumes can result in print quality issues due to excess inking. Consequently, the cell density may be limited by a minimally sufficient wall thickness355that is necessary for reliable use. Typically, the wall350has a thickness355of 1 micron or more for printing standard geometry lines and features. For example, in one example, the sum of the wall thickness355and the cell size345of an anilox roller115configured to deliver 0.5 BCM with 2000 lpi (lines per inch) is 12.7 microns, with the wall thickness355at approximately 1-2 microns and the cell size345at approximately 10.7-11.7 microns. For anilox rollers with lower cell density (or lpi), the cell size345will increase accordingly.

FIGS.6and7illustrate different views of an inking system400for transferring a plurality of different inks to a flexographic printing plate112(FIG.3) via an anilox roller115(FIG.3) in a flexographic printing system100(FIG.1) in accordance with an exemplary embodiment. The inking system400transfers ink to the anilox roller115using a fountain roller420having a plurality of ink transfer zones422a,422b,422cseparated by recessed zones424a,424b. The radius of the fountain roller420in the recessed zones424a,424bis smaller than the radius of the fountain roller420in the ink transfer zones422a,422b,422c.

The exemplary inking system400provides the plurality of inks to the ink transfer zones422a,422b,422cof the fountain roller420using a segmented ink tray410having a plurality of ink tray segments418a,418b,418ccorresponding to each of the ink transfer zones422a,422b,422cof the fountain roller420. In the illustrated embodiment, the segmented ink tray410includes an ink tray insert430inserted into a conventional ink tray411. In the illustrated configuration, the ink tray insert430is configured to supply ink to the central ink transfer zone422bof the fountain roller420.

The fountain roller420is positioned such that the ink transfer zones422a,422b,422ccontact the cylindrical outer surface of the anilox roller115(FIG.3). Each ink transfer zone422a,422b,422cof the fountain roller420is adapted to receive ink from the corresponding ink tray segment418a,418b,418cand transfer the received ink to a corresponding zone of the anilox roller115. In some embodiments, the anilox roller115can be a segmented anilox roller115that has characteristics that vary across its cross-track width. For example, the segmented anilox roller can have different characteristics in the zones corresponding to the ink transfer zones422a,422b,422cto control the volume of ink transferred in each zone. In some embodiments, the anilox roller115can have surface characteristics in the regions between the ink transfer zones422a,422b,422cto prevent intermixing of the different inks (e.g., the surface can include no cell structure in the regions between the ink transfer zones422a,422b,422c).

The conventional ink tray411has end walls412,413and a bottom surface414. The bottom surface414can have a wide variety of shapes. In the illustrated configuration, the bottom surface414includes multiple planar segments which together define a composite surface having an inner profile415. In various embodiments, the planar segments can be joined by sharp boundaries or by rounded boundaries that smoothly transition from one segment to another. In some embodiments, the bottom surface414can include one or more curved non-planar segments. Bearing saddles416are mounted adjacent to the end walls412,413and are adapted to receive bearings426mounted on the shaft of the fountain roller420.

The ink tray insert430, which is shown in more detail inFIG.8, has a bottom surface433, a left side wall431that extends upward from a left edge434of the bottom surface433and a right side wall432that extends upward from a right edge435of the bottom surface433. The left and right side walls431,432are configured to extend into the recessed zones424a,424bof the fountain roller420. In the illustrated configuration, the left and right side walls431,432include notches438into which the recessed zones424a,424bof the fountain roller420fit.

The ink tray insert430has an outer profile436that substantially conforms to the inner profile415of the bottom surface414of the conventional ink tray411such that the ink tray insert430fits snugly within the conventional ink tray411. Within the context of the present disclosure “substantially conforms to” means that the ink tray insert430fits within the conventional ink tray411such that any gaps between the outer profile436of the ink tray insert430and the inner profile415of the conventional ink tray are less than 3 mm, and preferably less than 1 mm. The bottom surface433of the ink tray insert430should be thin enough such that the outer surface of the fountain roller420in the ink transfer zone422bdoes not come into contact with the bottom surface433when the fountain roller is mounted in the conventional ink tray411. In an exemplary embodiment, acceptable clearance was obtained when the thickness of the bottom surface433was set to be 0.040″. The ink tray insert should preferably be made of a material which is washable and sufficiently rigid given the thicknesses of the left and right side walls431,432and bottom surface433to provide durability and robustness when it is being handled. In an exemplary embodiment, the ink tray insert430is machined from high-density polyethylene (HDPE), and the thickness of the left and right side walls431,432is 0.125″. In an alternate embodiment, the left and right side walls431,432and the bottom surface433of the ink tray insert430are laser cut from 304 stainless steel, then formed and welded.

In the illustrated configuration, a single ink tray insert430is used to supply ink in ink tray segment418bto a single ink transfer zone422bof the fountain roller420. Ink is added to the conventional ink tray411in the ink tray segments418a,418cto supply ink to the other ink transfer zones422a,422c. In other configurations, a plurality of ink tray inserts430can be used to supply ink to a corresponding plurality of the ink transfer zones422a,422b,422cof the fountain roller420. In some configurations, an ink tray insert430is provided for each of the ink transfer zones422a,422b,422c.

In various embodiments, the inks supplied in each of the ink transfer zones422a,422b,422ccan be the same or different. In an exemplary embodiment, the ink tray insert430is used to supply a transparent ink to the central ink transfer zone422b, and an opaque ink is supplied to the outer ink transfer zones422a,422c(for example, to print fiducial marks that are useful for aligning the printed pattern). Within the context of the present disclosure, a transparent ink (sometimes referred to as a colorless ink) is one which produces a printed pattern that changes the optical density (either in transmission or reflection) by less than 0.1 in a specified detection wavelength range, and an opaque ink is one which produces a printed pattern that changes the optical density by at least 0.3 in a specified detection wavelength range. Examples of transparent inks would include dielectric inks, adhesive inks, silver nanowire inks, carbon nanotube inks, polymeric inks, and inks having a low-concentration of various particulates which are useful for various applications including printed electronics applications and security feature printing applications.

In other embodiments, any appropriate inks can be utilized in the different ink transfer zones422a,422b,422c, which can have corresponding transparency characteristics, which can include cases where all of the inks are transparent. For example, in some exemplary embodiments, a high-cost ink is supplied in one ink transfer zone422b(e.g., a functional ink that is useful for forming electrical components), and a low-cost ink is supplied in other ink transfer zones422a,422c(e.g., an opaque ink for printing fiducial marks that are useful for aligning the printed pattern). Within the context of the present disclosure, a “low-cost ink” is one that has a lower cost per unit volume than the “high-cost ink.” An example of a high-cost ink would be a conductive ink including silver particles which are useful for some printed electronics applications. Other high-cost inks would include many specialty functional inks. In other applications, different inks are required at different cross-track locations in accordance with the layout of the pattern being printed. In this case, corresponding inks can be supplied in each of the different ink transfer zones422a,422b,422cin accordance with such embodiments.

The use of the one or more ink tray inserts430has the advantage that a conventional ink tray411can easily be converted into a segmented ink tray410such that a plurality of different inks can be supplied in a conventional printing system in different ink transfer zones422a,422b,422c. It has the additional advantage that a smaller volume of ink can be used to supply ink to a particular ink transfer zone422bhaving a cross-track width Withat is substantially narrower than the cross-track width Wtof the conventional ink tray411. Typically, Wiwill be less than Wt/2, and often will be less than Wt/3. This can be particularly advantageous when the supplied ink has a high cost. The use of the ink tray inserts430has the additional advantage that they can be easily removed such that any unused ink can be recovered from the ink tray insert430. The ink tray inserts430of the present invention have the advantage over other products, such as the disposable pan liners available from DIPCO of Delta, CO that are not made of a rigid material, that they can be easily cleaned and reused, thus providing improved sustainability.

FIG.9illustrates an alternate embodiment of an inking system405utilizing a segmented ink tray440having fixed dividing walls442that separate the segmented ink tray440into the plurality of ink tray segments418a,418b,418c. Fountain roller420is positioned within the segmented ink tray440and functions in a manner similar toFIG.6, which was discussed earlier. The dividing walls442extend into the recessed zones424a,424bof the fountain roller420. In the illustrated configuration, the dividing walls442have notches444into which the recessed zones424a,424bof the fountain roller420fit.

FIG.10Aillustrates an alternate embodiment of an inking system500employing a segmented ink tray540including a plurality of ink tray inserts510a,510b,510c, each of which utilizes a corresponding fountain roller element520a,520b,520c. Each fountain roller element520a,520b,520chas a corresponding ink transfer zone524. In an exemplary embodiment, the ink tray inserts510a,510b,510care adapted to fit within a conventional ink tray411to provide a segmented ink tray508. The ink tray inserts510a,510b,510cinclude bearing saddles516mounted adjacent to side walls531,532which are adapted to receive bearings526mounted on shafts522(seeFIG.11B) of the fountain roller elements520a,520b,520csuch that the fountain roller elements520a,520b,520care aligned in a coaxial configuration. The coaxial fountain roller elements520a,520b,520ccan collectively be referred to as a “fountain roller system.” The fountain roller elements520a,520b,520ccan also be referred to as “short fountain rollers” reflecting the fact that the cross-track widths of the ink transfer zones524are shorter than the cross-track width of the substrate150(FIG.1) being printed on, as well as the cross-track width of the conventional ink tray411. Within the context of the present disclosure, a short fountain roller is one having an ink transfer zone524with a cross-track width that is less than 50% of the cross-track width of the substrate150.

FIG.10Bshows a side view of the inking system500with a representative ink tray insert510and fountain roller element520. The ink tray inserts510have a bottom surface533with an outer profile536that substantially conforms to the inner profile415of the conventional ink tray411.

FIGS.11A-11Cshow additional details of ink tray insert510according to an exemplary embodiment. The ink tray insert510includes left and right side walls531,532which extend upwards from left and right edges534,535, respectively, of the bottom surface533. Bearing saddles516are mounted adjacent to the side walls531,532and are used to mount fountain roller element520within the ink tray insert510.

FIG.12illustrates an alternate embodiment of an inking system505using a segmented ink tray545including fixed dividing walls442that separate the segmented ink tray545into the plurality of ink tray segments418a,418b,418c. Bearing saddles516adapted to receive bearings526mounted on shafts of the fountain roller elements520a,520b,520care mounted adjacent to the end walls412,413and the dividing walls442. This enables convenient installation and removal of the fountain roller elements520a,520b,520c. Other elements of the inking system505are similar to the inking system405discussed earlier with respect toFIG.9.

FIG.13Ashows a cross section through the ink tray insert510ofFIG.11B, taken through cut line A-A′. The ink tray insert510is shown as being loaded with a volume of ink550which is deep enough so that it covers a lower portion of the bearing526. This permits ink to seep in between the bearing526and the bearing saddle516. This has the disadvantage that it can be difficult to clean the ink tray insert510and the bearing526of the fountain roller element520(e.g., when changing inks or recovering unused ink).

FIG.13Billustrates an alternate configuration which mitigates this disadvantage. In this case, a bearing guard560is added to the inward faces of the bearing saddle516which shields a lower portion of the bearing526such that ink cannot penetrate in between the bearing526and the bearing saddle516. In the exemplary configuration ofFIG.13B, the bearing guard560has a notch in the upper edge sized to receive the shaft522of the fountain roller element520(FIG.11B). In other configurations, the bearing guard560can have other shapes. For example, it can have a horizontal upper edge that extends to a height that is just below the shaft522of the fountain roller element520.

PARTS LIST