Color electro-optic displays, and processes for the production thereof

Abstract

A color filter array is provided in an electro-optic display by ink jet printing a plurality of colored areas (22R, 22G, 22B) on one surface of a layer of electro-optic material (12), an adhesive layer or a protective layer. Alternatively, the ink jet printing may be effected on the same layers in various sub-assemblies used to produce electro-optic displays.

Claims

1. An article of manufacture comprising, in order: a light-transmissive electrically-conductive layer; a layer of a solid electro-optic medium in electrical contact with the electrically-conductive layer; an adhesive layer; and a release sheet, wherein the adhesive layer has a plurality of first colored areas and a plurality of second colored areas printed on one surface thereof, the first and second colored areas being of different colors.

2. An article of manufacture comprising: a layer of a solid electro-optic medium having first and second surfaces on opposed sides thereof; a first adhesive layer on the first surface of the layer of solid electro-optic medium; a release sheet disposed on the opposed side of the first adhesive layer from the layer of solid electro-optic medium; and a second adhesive layer on the second surface of the layer of solid electro-optic medium, wherein one of the adhesive layers has a plurality of first colored areas and a plurality of second colored areas printed on one surface thereof, the first and second colored areas being of different colors.

3. An article of manufacture comprising, in order: a release sheet; a layer of a solid electro-optic medium; an adhesive layer; and at least one of a light-transmissive protective layer and a light-transmissive electrically-conductive layer, wherein the adhesive layer has a plurality of first colored areas and a plurality of second colored areas printed on one surface thereof, the first and second colored areas being of different colors.

4. The article of manufacture according to claim 1 wherein the electro-optic medium comprises a microcell electrophoretic medium, an encapsulated electrophoretic medium comprising a plurality of capsules in a binder, or a polymer-dispersed electrophoretic medium.

5. The article of manufacture according to claim 1 wherein the first and second colored areas comprise a radiation curable ink.

6. The article of manufacture according to claim 1 wherein the first and second colored areas comprise a solvent-based ink comprising pigment particles in an organic solvent.

7. The article of manufacture according to claim 2 wherein the electro-optic medium comprises a microcell electrophoretic medium, an encapsulated electrophoretic medium comprising a plurality of capsules in a binder, or a polymer-dispersed electrophoretic medium.

8. The article of manufacture according to claim 2 wherein the first and second colored areas comprise a radiation curable ink.

9. The article of manufacture according to claim 2 wherein the first and second colored areas comprise a solvent-based ink comprising pigment particles in an organic solvent.

10. The article of manufacture according to claim 3 wherein the electro-optic medium comprises a microcell electrophoretic medium, an encapsulated electrophoretic medium comprising a plurality of capsules in a binder, or a polymer-dispersed electrophoretic medium.

11. The article of manufacture according to claim 3 wherein the first and second colored areas comprise a radiation curable ink.

12. The article of manufacture according to claim 3 wherein the first and second colored areas comprise a solvent-based ink comprising pigment particles in an organic solvent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 to 4 of the accompanying drawings are schematic elevations showing various stages in a preferred electro-optic layer printing process of the present invention starting from a double release film.

(2) FIG. 5 illustrates the array of colored sub-pixels used in the preferred protective layer printing process of the present invention described in Example 2 below.

DETAILED DESCRIPTION

(3) As already mentioned, various aspects of the present invention make use of ink jet printing (including, possibly, so-called “solid ink jet printing” where the ink solidifies on contact with the surface being printed rather than drying on this surface) to form colored areas, and typically a color filter array, on the surface of an electro-optic material, lamination adhesive or protective layer used to form an electro-optic display. Hereinafter, the invention will mainly be described with reference to the formation of three or four color filter arrays, but it should be borne in mind that the invention extends to simpler processes involving only one or two colors, and to processes involving more than four colors.

(4) Although other color printing methods could, in principle, be used in place of ink jet printing; ink jet printing has the advantage that no colorant donor medium actually comes in contact with the layer being printed. Such contact can lead to severe problems; for example, an attempt to use a dye sublimation (dye diffusion thermal transfer) printer in a modification of an electro-optic layer printing process of the present invention led to the welding of the electro-optic layer to the dye donor sheet.

(5) It will be seen from the description above that the present invention provides numerous different processes for the formation of color filter arrays, and the choice of which specific process is adopted will in many cases be governed by the exact structure of the electro-optic display, the thicknesses of the various layers therein, and the processes used to assemble the various layers of the display. Typically (see, for example, FIG. 10 of the aforementioned U.S. Pat. No. 6,982,178 and FIG. 3 of the aforementioned 2007/0109219), an electro-optic display comprises (reading from the viewing surface to the backplane, downwardly as illustrated in these two Figures): (a) (optionally) barrier and other auxiliary protective layers; (b) a protective layer/front substrate; (c) a front electrode layer (in practice, layers (b) and (c) are often formed from a commercial two-layer film, such as poly(ethylene terephthalate)/indium tin oxide, so that it is not possible for the manufacturer of an electro-optic display to insert anything between these two layers); (d) (optionally) a front adhesive layer; (e) a layer of electro-optic material; (f) a rear adhesive layer; and (g) a backplane bearing pixel electrodes.
Since the electro-optic material is often opaque, a color filter array must normally lie between the electro-optic layer (e) and the viewing surface of the display. Furthermore, it is usually desired to keep the color filter array as close to the electro-optic layer as possible to avoid parallax problems. Hence, it is generally undesirable to place the color filter array (CFA) on the outside surface of layer (a) both because of the large separation from the electro-optic layer and because of the risk of mechanical damage to the CFA. This, there are potentially three interfaces where the CFA can be located, namely interfaces a/b, c/d and d/e. Furthermore, for each interface the CFA can be formed by printing on either one of the two adjacent layers. However, if is desired to print the CFA already registered with the backplane, it is advantageous to print on the layer closer to the backplane, provided that layer is already attached to the backplane at the time printing occurs.

(6) It should be noted that if the CFA is printed at interface c/d or d/e, the CFA will lie between the electrodes of the display, whereas if the CFA is printed at interface a/b it will not lie between the electrodes, and the required properties of the ink used differ in the two cases. If the CFA lies between the electrodes, it is important that the dielectric constant not be too high or kickback may occur. (“Kickback” or “Self-erasing” is a phenomenon observed in some electro-optic displays (see, for example, Ota, I., et al., “Developments in Electrophoretic Displays”, Proceedings of the SID, 18, 243 (1977), where self-erasing was reported in an unencapsulated electrophoretic display) whereby, when the voltage applied across the display is switched off, the electro-optic medium may at least partially reverse its optical state, and in some cases a reverse voltage, which may be larger than the operating voltage, can be observed to occur across the electrodes.) Conversely, if the CFA lies between the electrodes, it is important that the conductivity of the ink not be too high or blooming may occur. (“Blooming” is a phenomenon whereby the area of the electro-optic layer which changes optical state in response to change of voltage at a pixel electrode is larger than the pixel electrode itself) Humectants, non-aqueous solvents, and surfactants are commonly employed in commercial ink jet inks, and these materials can potentially interfere with the electro-optic properties of the electro-optic material, for example by changing the conductivity of the electro-optic layer, and hence can cause unexpected behavior if present between the display electrodes. Also, in all processes of the present invention the colorants in the ink should be transparent when dry, so that either dyes or very small particle pigmented inks should be used. Transparent pigmented inks are highly desirable in the present process, because such inks will not penetrate appreciably into the electro-optic layer, and, when the electro-optic layer is an electrophoretic layer, cannot interact unfavorably with the internal phase (electrophoretic particles and surrounding fluid) of this electrophoretic layer. Radiation curable (typically ultraviolet curable) inks have been found very suitable for use in the present processes, as have (organic) solvent-based pigment inks. The latter can be formulated using very small amounts of polymeric binders so that the dried ink layer is of minimal thickness and minimal effect on the performance of the electro-optic material. Subject to the foregoing considerations, any known type of ink jet printer can be used. Clearly, for very high resolution, good positioning and uniform ink deposition is important.

(7) Furthermore, as already mentioned the choice of which layer is to ink jet printed by a process of the present invention to form a CFA is greatly affected by the “construction method” used to form the display (i.e., the order in which the various layers are assembled to form the display). Three common constructions methods will now be discussed, although others will ready by apparent to those skilled in the technology of electro-optic displays.

(8) Construction Method A

(9) As described in the aforementioned U.S. Pat. No. 6,982,178, one method commonly used to produce electro-optic, and especially encapsulated or polymer-dispersed electrophoretic, displays begins by coating the electrophoretic medium on to a PET/ITO film. Separately, a lamination adhesive is coated on to a release sheet. The lamination adhesive/release sheet sub-assembly is then laminated to the electrophoretic layer to form a front plane laminate, typically on a roll-to-roll basis. The front plane laminate is then cut to a size needed for an individual display, the release sheet is removed and the remaining layers laminated to a backplane, typically a thin film transistor (TFT) active matrix backplane. In this process, because the electrophoretic material layer, layer (e) above, is deposited directly on the front substrate/front electrode layer, layers (b)/(c) above, with no intervening front adhesive layer (d), the only surface available for ink jet printing is the exposed surface of the front substrate, layer (b), i.e., a PLP method of the present invention needs to be used. Ink jet printing on this surface after the front plane laminate has been laminated to the backplane is essentially printing on a fully-functional active matrix display. Thus, the display can be imaged to a fiducial pattern before printing the CFA, thus taking advantage of an RIJP process of the present invention and easing registration of the color filter array with the pixel electrodes in the backplane.

(10) Construction Method B

(11) Other less common methods for producing electro-optic displays offer more options for introducing a color filter array by ink jet printing. One such method is to coat the electro-optic material directly on to a backplane, separately coat lamination adhesive to a PET/ITO front substrate, and laminate the two resulting sub-assemblies together. This method allows ink jet printing of a CFA directly on to the electro-optic layer before the final lamination step. Such an EOLP process of the present invention has an advantage that the CFA is in intimate contact with, and hence as close as possible to, the electro-optic layer, thereby eliminating any possible light-piping or parallax problems due to light entering through one CFA sub-pixel and leaving through a different sub-pixel. However, this approach does limit the choice of ink jet inks as discussed above, as the CFA is interposed between the two electrodes and in contact with the electro-optic layer. It also requires coating the electro-optic material directly on to the backplane, which is typically a batch process instead of the roll-to-roll process possible in Construction Method A above.

(12) A variant of the construction method described in the preceding paragraph using a double release sheet permits roll-to-roll coating of the electro-optic material. In this variant, the electro-optic material is coated on to a disposable first release sheet. Separately, a lamination adhesive is coated on to a second release sheet, and the lamination adhesive is laminated to the electro-optic material to form a double release sheet having the structure first release sheet/electro-optic material/lamination adhesive/second release sheet. The second release sheet is then removed, and the remaining layers laminated to a backplane. The first release sheet can then be removed and a PET/ITO front substrate/front electrode laminated over the electro-optic material to produce a final display having the optional front adhesive layer. As discussed in the aforementioned 2007/0109219, this method also requires judicious use of differential release sheets to enable the second release sheet to be peeled from the double release film without disturbing the first release sheet.

(13) Construction Method C

(14) As already indicated, a preferred ALP process of the invention involves ink jet printing on a lamination adhesive layer overlying an electro-optic layer, which is itself already in position on a backplane. A preferred method for forming the lamination adhesive/electro-optic layer/backplane intermediate structure, which minimizes the number of times the (typically) fragile backplane is laminated is as follows. A first release sheet/electro-optic material/lamination adhesive/second release sheet structure is formed as described in Construction Method B above. However, in this case, a second lamination adhesive layer is coated on to a third release sheet, the first release sheet is removed and the electro-optic layer laminated to the second lamination adhesive layer to form a double release film. One of the release sheets is removed from this double release film and the remaining layers laminated to a backplane. This method also requires judicious use of differential release sheets.

(15) One preferred form of the EOLP process of the present invention comprises the following steps: (a) a layer of an encapsulated electrophoretic material or polymer-dispersed electrophoretic material is coated on to a backplane comprising at least one pixel electrode; (b) a color filter array is printed directly on the electrophoretic material layer using an ink jet printer; (c) the electrophoretic material layer, color filter array and backplane are dried in an oven to remove the volatile components of the ink jet ink; and (d) the electrophoretic material layer with the dried color filter array thereon is laminated via a lamination adhesive to a front substrate which provides a light-transmissive front electrode for the final display and (normally) a protective layer which supports and provides mechanical protection to this front electrode, and optionally any desired barrier or radiation-absorbing layers; this step is conveniently effected by coating a layer of the lamination adhesive on a release sheet, drying the lamination adhesive layer, laminating the dried layer to the surface of the electrophoretic material layer, peeling the release sheet and then laminating the thus-exposed surface of the lamination adhesive to the front substrate.

(16) It is well known to those skilled in the technology of encapsulated electrophoretic media that, as described in some of the aforementioned E Ink and MIT patents and applications, when an encapsulated electrophoretic medium, including a polymer-dispersed electrophoretic medium, is coated on a smooth surface, such as the surface of a release sheet, the resultant layer of electrophoretic medium has a smooth surface facing the surface on which it is coated and a rough surface on its opposed side, the roughness of this surface being caused by shrinkage of the medium as it is dried or cured, and consequent protrusion of capsule or droplets from the surrounding surface. The preferred process of the invention described above places the color filter array on the rough surface of the electrophoretic medium. If it is desired to form the color filter array on the smooth side of the electrophoretic medium (which may, at least in some cases, result in more precise printing of the color filter array), the electrophoretic medium may be coated on a release layer, and laminated to a backplane with lamination adhesive. (This is conveniently done in the manner described in the aforementioned U.S. Pat. No. 7,110,164 by coating the electrophoretic medium on a first release sheet, coating the lamination adhesive on a second release sheet, laminating the two resultant structures together with the lamination adhesive contacting the electrophoretic medium, and thereafter peeling the second release sheet from the lamination adhesive; the two release sheets of course being chosen so that this peeling can be effected without disturbing the first release sheet.) After this lamination, the first release sheet is removed from the electrophoretic medium and the color filter array printed on the smooth side of the electrophoretic medium thus exposed. The remaining steps of the process are essentially unchanged.

(17) A second preferred EOLP process of the invention, illustrated in the accompanying drawings, can readily be applied to the production of an active matrix display. The drawings are not strictly to scale; in particular, the thicknesses of the various layers are greatly exaggerated relative to the lateral dimensions of the layers. The process begins as described in the aforementioned U.S. Pat. No. 7,110,164 by coating an electrophoretic medium 12 on a first release sheet 14, coating as thin a layer as possible of a lamination adhesive 16 on a second release sheet 18, and laminating the two resultant structures together with the lamination adhesive 16 contacting the electrophoretic medium 12, to form the structure shown in FIG. 1. Thereafter, the second release sheet 18 is peeled from the lamination adhesive 16, and the remaining layers 12, 14 and 16 are laminated to an active matrix backplane 20 provided with fiducial marks (not shown) to form the structure shown in FIG. 2. High precision registration is not required during this lamination.

(18) The first release sheet 14 is then removed from the electrophoretic medium 12, thus exposing the smooth surface of this medium, and a color filter array (indicated schematically as comprising red, green and blue color stripes 22R, 22G and 22B respectively in FIG. 3) is ink jet printed on this smooth surface using a high precision inkjet printer and positioning system relying upon the fiducial marks formed on the backplane 22. In a manufacturing environment, this step is easily automated. Note that this technique avoids delicate alignment of a pre-formed color filter array with the backplane, the positioning and alignment of the color filter array being controlled by the fiducial marks formed on the backplane 22 itself. The fiducial marks themselves can readily be located with high accuracy as part of the patterning procedures used during manufacture of the backplane.

(19) The color filter array is then dried by any convenient method, and a front substrate comprising a transparent electrode 24 and a support layer 26 is laminated over the color filter array by means of a lamination adhesive 28, as shown in FIG. 4. For reasons discussed in the aforementioned 2007/0109219, the lamination adhesive 28 is desirably relatively conductive to provide the final display with good low temperature performance characteristics. Finally, if desired any barrier layers 30 may be provided over the support layer 26 to provide moisture and oxygen barriers and ultra-violet radiation filtering. Edge seals may also be provided around the periphery of the display, as described for example in the aforementioned U.S. Pat. No. 6,982,178.

(20) Note that in both preferred EOLP processes of the present invention described above, the color filter array is formed on the electrophoretic medium layer after that layer is already present on the backplane. Forming the color filter array in this manner avoids any problems caused by dimensional changes in an electrophoretic layer bearing a color filter array during lamination of such an electrophoretic layer to a backplane.

(21) Typically, in the various processes of the present invention, it is desirable that the colorant in the ink jet ink be confined as close as possible to the surface of the layer to which it is applied. When the ink jet ink is being applied to the electro-optic layer itself, such confinement is desirable not only because the surface of electro-optic layer is where the colorant serves its color-controlling function, but also because such confinement of the colorant renders it less likely to compromise the electro-optic performance of the electro-optic layer. In other processes, it is generally desirable to avoid the ink diffusing through the layer to which it is applied since such diffusion may cause intermixing of various colored areas and thus degradation of the color shown on the display. The use of transparent pigmented inks is therefore preferred. If dye-based inks are to be used, it may be desirable to include mordant polymers in the layer to which the ink is applied, for example as a constituent of the binder in an encapsulated electrophoretic medium layer. Such mordant polymers contain groups capable of binding otherwise soluble dyes and confining them to a surface portion of the ink-receiving layer. The preferred binders for use in encapsulated electrophoretic media are typically anionically charged, and hence can be expected to act as mordants for cationic dyes, so cationic inks are preferred for use with such binders. Incorporation of metal ions into the ink-receiving layer may mordant suitable ink jet dyes or precursors by coordination of the metal. The resulting complexed, mordanted dyes frequently show enhanced stability against photo-degradation.

(22) Most ink jet inks, particularly those for use in inexpensive printers designed for home and small office use, contain substantial amounts of humectants, for example ethylene glycol, methoxy ethanol, glyme, and other similar hydrophilic species. These materials tend to be deleterious in the present process, and their use should be minimized. A commercial ink jet ink formulation can be produced with very much smaller humectant concentrations, since a major function of these materials is to prevent nozzle clogging caused by drying of the printer ink. Ink jet inks with minimal amounts of humectants are preferred for use in the present process. To the extent that humectants are necessary, volatile materials with minimal ability to swell the ink-receiving layer, and especially the cell walls of encapsulated electrophoretic media, should be used.

(23) Ink jet inks often contain surfactants, some of which may show deleterious effects in electro-optic media, for example by affecting the switching performance of encapsulated electrophoretic media, the internal phases of which often contain surfactants carefully chosen to maintain electrophoretic particle stability and switching performance. Anionic surfactants, particularly those with very low critical micelle concentrations, appear to be particularly problematical in this respect. In any case, the surfactant type and concentration in the ink jet ink should be optimized and minimized for the present process, and for compatibility with electro-optic performance.

(24) The following Examples are now given, though by way of illustration only, to show details of particularly preferred reagents, conditions and techniques used in the processes of the present invention.

EXAMPLE 1

(25) This Example illustrates an adhesive layer printing process of the present invention using Construction Method C described above.

(26) An encapsulated electrophoretic medium was prepared comprising gelatin/acacia capsules having an internal phase comprising polymer-coated titania white particles and polymer-coated copper chromite black particles in a hydrocarbon fluid. The capsules were formed into a slurry using an aqueous polyurethane binder substantially as described in Example 4 of the aforementioned U.S. Pat. No. 7,002,728. The resultant capsule slurry was slot coated on to a loose release sheet and dried to form a loose release sheet/capsule layer sub-assembly. Separately, a custom polyurethane adhesive was coated on to a tight release sheet, and then laminated to the loose release sheet/capsules layer sub-assembly, with the adhesive layer contacting the capsule layer. Separately, a polyacrylate adhesive was coated on to a loose release sheet. The loose release sheet was peeled from the capsule layer, and the exposed surface of the capsule layer laminated to the polyacrylate adhesive on the loose release sheet, to form a double release film having the following sequence of layers:

(27) loose release sheet/polyacrylate adhesive/capsule layer/polyurethane adhesive/tight release sheet.

(28) From this double release film, there was laser cut a portion of a size appropriate for a 6.1 inch (155 mm) electrophoretic display. The loose release sheet was peeled from the polyacrylate adhesive and the remaining layers of the double release film were laminated to a 6.1 inch (155 mm) thin film transistor active matrix backplane. The tight release sheet was then peeled from the polyurethane adhesive to expose the surface of this adhesive for ink jet printing.

(29) The exposed polyurethane adhesive surface was then ink jet printed using a Dimatix DMP-5000 Material Deposition Printer (available commercially from Fujifilm Dimatix, Inc., 2230 Martin Avenue, Santa Clara Cali. 95050, United States of America) using 16 jet piezoelectric heads (available as disposable cartridges through Dimatix). Generally 2-3 heads were used per print to improve jetting quality. The inks used were Sunjet Crystal UV curable ink in cyan (Crystal UDG U4970 Cyan Jet Ink), magenta (Crystal UDGU4896 Magenta Jet Ink), and yellow (Crystal UDG U4970 Yellow Jet Ink). A 30 μm drop spacing was used. The printed area consisted of 800 pixels in the x direction and 600 sub-pixels in the y direction, each pixel being 153×151 μm. These pixels were overprinted together in groups of 4×600 pixels, forming a series of 0.612 by 90.4 mm bars (200 bars in total, 67 each cyan and magenta bars and 66 yellow bars).

(30) The printer was charged and calibrated with a cyan print cartridge. The backplane/double release film was placed in the printer and a fiducial mark on the backplane was found using Dimatix optics and software. The cyan bars were then printed. The printed backplane/double release film was then removed from the printer and bombarded with 20 W/inch (0.8 W/mm) of ultraviolet radiation to cure the deposited ink. The process was then repeated with magenta and yellow inks, each color being offset by 0.612 mm in the x direction.

(31) To complete the display, a 5 mil (127 μm) PET film bearing an ITO coating on one surface was cut to the size needed for the display, and laminated to the exposed, printed adhesive layer, with the ITO-coated surface in contact with the printed adhesive layer.

EXAMPLE 2

(32) This Example illustrates a printed protective layer process of the present invention using Construction Method A above.

(33) An encapsulated electrophoretic display was prepared by coating capsules similar to those described in Example 1 above on the ITO-coated surface of a PET/ITO film and drying, separately coating a custom polyurethane adhesive on to a release sheet, and laminating the adhesive/release sheet sub-assembly to the PET/ITO/capsule layer sub-assembly, with the adhesive contacting the capsule layer to form a front plane laminate. This front plane laminate was cut to size, the release sheet removed and the remaining layers laminated to a thin film transistor active matrix backplane to form a monochrome display. All the preceding steps were carried out substantially as described in the aforementioned U.S. Pat. No. 6,982,178.

(34) The display thus prepared was ink jet printed using the same printer and inks as in Example 1 above. Printing was effected using the arrangement shown in FIG. 5 of the accompanying drawings, in which a single pixel is represented by the 6×6 area within the heavily lined box. As may be seen from FIG. 5, the 6×6 pixel is anisotropic, comprising a 3×4 cyan sub-pixel, a 3×4 magenta sub-pixel and a 6×2 yellow sub-pixel. This pixel is tessellated to fill the entire display, with adjacent pixels being inverted relative to one another in the vertical direction (as illustrated in FIG. 5) so that the repeating unit on the backplane, as shown in FIG. 5, was similar to the pixel unit but twice as large in each direction.

(35) The cyan sub-pixels were printed first as a matrix of 0.918 by 1.208 mm rectangles offset by 1.836 mm in the x direction and 2.416 mm in the y direction. The display was removed from the printer and bombarded with 20 W/in (0.8 W/mm) of ultraviolet radiation to cure the printed ink. The same pattern, offset by 0.918 mm in the x direction, was printed using magenta ink, followed by another curing step. Finally a series of yellow stripes 120.8 by 0.604 mm was printed in the remaining area and cured.

(36) The present processes provide several major advantages:

(37) (a) the processes can be used for rapid construction of prototype color displays, even active matrix displays, since the process is well adapted for “one-off” production and no expensive masks or similar devices are required for each new type of color filter array.

(38) (b) no expensive pre-formed color filter array is required; the array is produced on demand by printing directly on the desired layer. The cost of the resulting display is greatly reduced as a result. This saving is particularly important for larger displays.

(39) (c) the optical performance of the display is not degraded because of multiple optical layers, as in the case of a separately constructed, laminated color filter array or overlay. Further, in many processes of the present invention intimate contact between the colorant and the imaging layer means that there is no optical degradation resulting from parallax.

(40) (d) the construction and manufacture of the color display is simplified because the alignment and application of the colored areas is facilitated: it is easier to position the active matrix backplane using fiducial marks built into that portion of the display than to align a pre-formed color filter array with the backplane in two dimensions. This method of construction would also be more amenable to flexible backplanes, since ink jet printing allows for correction for dimensional changes of the backplane during manufacture.

(41) Numerous changes and modifications can be made in the preferred embodiments of the present invention already described without departing from the scope of the invention. Accordingly, the foregoing description is to be construed in an illustrative and not in a limitative sense.