TWI454787B - Reflective displays and processes for their manufacture - Google Patents

Description

Reflective display and method of manufacturing same

The present invention relates to a reflective display and a method of fabricating the same.

Electronic paper has been developed based on a variety of display technologies, such as electrophoretic displays, nano color displays, electrodeposition displays, liquid powder displays, torsion ball displays, or liquid crystal display technologies.

One method of bringing the electronic paper to a multi-color state is to use a color filter. In general, a color filter is placed on the front surface of the display panel and produces different image colors depending on the "on" or "off" state of each sub-pixel. For a reflective display, the ambient light falls on the display surface, contrasting the difference between the reflected light from the "on" sub-pixel and the reflected light from the "off" sub-pixel that absorbs the light. By the color filter in front of the display panel, the light passes through the color filter before the "on" and "off" sub-pixels, and the reflected light is folded back through the color filters. Because color filters have limited transparency, when light passes through the color filter twice, a significant loss in reflectivity is typically observed, thus significantly reducing display contrast and color saturation. Therefore, although color filters have been used in the display industry, their achievements in reflective displays have been rather limited. In addition, the high cost of color filters is another disadvantage.

It is an object of the present invention to provide a reflective display that is cost effective and has high color quality.

The present invention is directed to a novel design of a reflective display that can be applied to most display technologies.

A first aspect of the invention relates to a novel design of a reflective display.

A second aspect of the invention relates to a method of making such a reflective display.

A third aspect of the invention relates to a configuration suitable for use in a display cell of a reflective display of the invention.

A fourth aspect of the invention relates to a reflective direct drive (or segment) display.

It is to be noted that the entire contents of each of the cited references in this application are hereby incorporated by reference.

Detailed descriptions of preferred embodiments of the invention are provided below. Although the present invention has been described in connection with the preferred embodiments, it should be understood that the invention is not limited

In the past, one method of producing a multi-color display was to use a colored image forming fluid or a colored filter. The present invention uses a novel method that includes the use of a "double reflection" mechanism to produce a color contrast with the color enhancement elements of the display panel. In this "double reflection" mechanism, the primary reflection is derived from image-forming elements (such as high-scattering particles in an electrophoretic fluid), and the contrast color is a color-enhancing element impregnated in an image-forming element (such as an image-forming electrophoretic fluid unit). produce. By the change of the area ratio of the color-increasing element and the image-forming element of the display panel, and by the color of the color-increasing element and the color of the image-forming element, the "double-reflection" mechanism can produce a unique color sense to the viewer with good optical contrast.

When a transparent component (e.g., a separation wall separating the image forming fluid units) is placed in the image forming fluid unit, color enhancement can be achieved, for example, by placing the color enhancement layer behind the image forming element. The transparent components allow light to pass through the opaque image forming element to the color enhancing layer. Alternatively, color enhancement can be achieved by placing a colored component in an image forming fluid component unit. In this case, the combination of the scattered light of the image forming fluid and the reflected color of the colored component will provide a variety of tones.

Note that although the present application specifically discusses electrophoretic displays, the inventive concepts are applicable and can be modified for use with other types of display technologies.

I. Design of reflective display

A first specific embodiment of the invention is depicted in Figure 1. This figure is a cross-sectional view of the design of a reflective display of the present invention. The display panel (10) of Figure 1 includes an array of display cells (11) filled with display fluid. The display panel (10) is sandwiched between the first electrode layer (12) and the second electrode layer (13). The display can be viewed from the side of the first electrode layer (12) or the side of the second electrode layer (13). In other words, one of the two electrode layers (12 or 13) is transparent for viewing. The color enhancement layer (14) is located between the display panel and an electrode layer, and the color enhancement layer (14) is located on the non-viewing side.

In a specific embodiment of the design, the second electrode layer (13) may have a reflective surface. Alternatively, a reflector (not shown) is disposed between the color enhancement layer (14) and the second electrode layer (13). Alternatively, if the second electrode layer is transparent or translucent, a reflector (not shown) may be placed behind the second electrode layer (13).

The color enhancement layer (14) itself may also have reflective features.

The dividing wall (15), which may also be referred to as a "dividing track", separates the display cells. In the context of the present invention, the dividing wall (or channel) may be transparent, translucent, light transmissive or semi-transmissive.

In FIG. 1, if the first electrode layer (12) is on the viewing side, and the color enhancement layer (14) is interposed between the display panel (10) and the second electrode layer (13), the color of the color enhancement layer is transparent. The lane is transmitted to the viewer.

The electrode layers (12 and 13) may be electrode layers having wires formed thereon. When the electrode layer is transparent, the electrode layer is usually formed of ITO (Indium Tin Oxide).

For direct drive displays, one electrode layer is a common electrode layer and the other electrode layer is a bottom plate of segment pixels. In other words, the display panel (10) is sandwiched between the common electrode layer and the bottom plate. The common electrode layer is usually the viewing side. The base plate can be formed from a flexible or rigid printed circuit board. In this case, the color enhancement layer is located between the display panel and the bottom plate. As discussed above, the bottom plate can have a reflective surface. Alternatively, a reflector can be placed between the color enhancement layer (14) and the substrate. Additionally or alternatively, the color enhancement layer itself may have reflective features.

The color enhancement layer (14) can be formed from a polymeric material. The materials described below for forming the display cells (i.e., microcups) are also suitable for forming the color enhancement layer.

The color enhancing layer may have a thickness in the range of from about 0.5 microns to about 10 microns, preferably in the range of from about 1 micron to about 5 microns.

The color enhancement layer can be an adhesive layer. The preferred material for the adhesive layer can be formed from an adhesive or a mixture thereof such as a pressure sensitive, hot melt or radiation curable adhesive. Specific adhesive materials may include, but are not limited to, acrylic, styrene-butadiene copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer , polyvinyl butyral, cellulose acetate butyrate, polyvinylpyrrolidone, polyurethane, polyamine, ethylene-vinyl acetate copolymer, epoxide, polyfunctional acrylate , ethylene, vinyl ether and oligomers, polymers or copolymers thereof. An adhesive comprising a polymer or oligomer having a high acid or base content, such as a polymer or copolymer derived from acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, vinyl pyridine or a derivative thereof It is especially useful.

The color enhancing layer comprises a dye or pigment or a mixture of dyes or pigments. Any dye or pigment that is soluble or dispersible in a composition for forming the color enhancement layer can be used. Most suitable dyes or pigments are commercially available, to name a few examples, available from Sun Chemical, BASF, Ciba Specialty Chemicals, Clariant, Daicolor-Pope or Bayer. Specific examples of suitable dyes or pigments include, but are not limited to, Cu phthalocyanine, quinacridone, benzimidazolone or carbon black.

The color enhancement layer (14) can be applied to the electrode layer (13) by lamination, direct printing, coating, screen printing, embossing or other equalization.

Alternatively, the color enhancement layer (14) may be laminated, directly printed, coated, screen printed, embossed (or by other equal means) on one side of the release liner. A release liner having the color enhancement layer is then laminated on the electrode layer in such a manner that the color enhancement layer is in contact with the electrode layer, and then the release liner is removed.

Alternatively, the release liner having the color enhancement layer is laminated on a display panel in such a manner that the color enhancement layer is in contact with the display panel, and then the release liner is removed. A display panel having the color enhancement layer is then laminated on the electrode layer to form a composite layer, wherein the color enhancement layer is between the electrode layer and the display panel.

A display panel formed by microcup technology as disclosed in U.S. Patent No. 6,930,818 (corresponding to WO 01/67170) is hereby incorporated by reference herein in its entirety in its entirety in its entirety herein in A typical micro-cup display panel is depicted in Figure 2.

The microcups (20) may be directly formed on the color enhancement layer (14) of FIG. 1 by microembossing or photolithography, or formed on the non-conductive substrate layer (21) shown in FIG. 2, respectively.

Materials suitable for forming the microcups can include, but are not limited to, thermoplastic or thermoset precursors, particularly polyfunctional acrylates, methacrylates, vinyl ethers, epoxies, and oligomers or polymers thereof. More preferred are polyfunctional acrylates and oligomers thereof. Combinations of polyfunctional epoxides with polyfunctional acrylates can also be used to obtain the desired physico-mechanical properties of the microcups. The glass transition temperature (or Tg) of the material suitable for forming the microcup may range from about -70 ° C to about 150 ° C, preferably from about -20 ° C to about 50 ° C.

The microcups are then filled with display fluid (22) and sealed with a polymeric sealing layer (23). Such filling and sealing methods are also disclosed in U.S. Patent No. 6,930,818 (corresponding to WO 01/67170). In short, the polymeric sealing layer can be hardened in situ. According to U.S. Patent No. 6,930,818, the sealing composition for forming a polymeric sealing layer preferably has a lower specific gravity than the display fluid.

If individually prepared, a microcup-based display panel can be laminated from the seal layer side (labeled "S" in Figure 2) to the color enhancement layer (14) of Figure 1. Alternatively, the display panel may be laminated on the color enhancement layer from the side of the microcup (labeled "M" in Fig. 2) after removing the non-conductive substrate layer (21).

After the display panel is placed in place, another electrode layer (such as electrode layer 12 of FIG. 1) is optionally laminated to the display panel (10) by an adhesive layer.

While the invention has been described using microcups, it should be understood that all of the inventive designs can be applied to other types of display technologies. For example, the design of Figure 1 can be applied to other types of display technology as long as the display cells are separated by a transparent, translucent, light transmissive or semi-transmissive wall or partition. The design of the present invention can also be applied to a display panel in which the display cells of the display panel are embedded in a transparent, translucent, light transmissive or semi-transmissive polymer substrate.

For example, the design of Figure 1 can be applied to a fast reacting liquid powder display containing partition walls similar to these microcup structures. Thus, the color enhancement layer can also be used in displays of this type to form a reflective display based on a combination of different image colors as described below.

In another example, if the polymer substrate or the separator is transparent, translucent, light transmissive or semi-transparent, the same method as described below may be used to form a microcapsule-based display cell buried in the polymerization. A reflective display in or separated by a spacer.

For electrophoretic displays, the cell is shown filled with charged pigment particles dispersed in a dielectric solvent or solvent mixture. The electrophoretic display fluid can be prepared according to methods well known in the art, for example, U.S. Patent Nos. 6,017,584, 5,914,806, 5,573,711, 5,403,518, 5,380,362, 4,680,103, 4,285,801, 4,093,534. , 4, 071, 430, 3, 668, 106 and IEEE Trans. Electron Devices, ED-24, 827 (1977) and J. Appl. Phys. 49 (9), 4820 (1978). The charged pigment particles are visually contrasted with a dielectric solvent or solvent mixture that disperses the charged particles. The dielectric solvent or solvent mixture preferably has a low viscosity and a dielectric constant in the range of from about 2 to about 30 to achieve high particle mobility. Examples of suitable dielectric solvents include, but are not limited to, hydrocarbons such as DECALIN, 5-ethylidene-2-norbornene, fatty oils, paraffinic oils, aromatic hydrocarbons such as toluene, Xylene, phenyldimethylphenylethane, dodecylbenzene and alkylnaphthalene, halogenated solvents such as perfluorodecalin, perfluorotoluene, perfluoroxylene, dichlorobenzotrifluoride, 3,4,5- Trichlorobenzotrifluoride, chloropentafluorobenzene, dichlorodecane, pentachlorobenzene, and perfluorinated solvents, such as FC-43, FC-70, and FC-5060, available from 3M Company, St. Paul, Minnesota, low A molecular weight halogen-containing polymer such as poly(perfluoropropene oxide) available from TCI America of Portland, Oregon, poly(chlorotrifluoroethylene), such as Halocarbon Product, available from River Edge, New Jersey. Halocarbon Oils, perfluoropolyalkyl ethers such as Galden from Ausimont or Krytox oils and Greases K-Fluid Series from DuPont, Delaware. One specific manifestation is the use of poly(chlorotrifluoroethylene) as a dielectric solvent. Another specific manifestation is the use of poly(perfluoropropene oxide) as a dielectric solvent.

The dielectric solvent or solvent mixture medium can be colored with a dye or pigment (hereinafter referred to as "dye solution"). Particularly useful are nonionic azo groups and anthraquinone dyes. Examples of useful dyes can include, but are not limited to, Oil Red EGN, Sudan Red, Sudan Blue, Oil Blue, Macrolex Blue, Solvent Blue 35, Pylam Spirit Black and Fast Spirit Black from Pylam Products, Arizona, purchased from Sud Black Black by Aldrich, Thermoplastic Black X-70 from BASF, Indigo, Eosin 114, Eosin 111, 135, Emerald Green 28 from Aldrich. Other suitable pigments and dyes include those disclosed in U.S. Patent Application Serial No. 10/439,428 (corresponding to WO 03/097747) and 10/903,923 (corresponding to WO 05/17046), the entire contents of In this article.

In the case of using an insoluble pigment, the pigment particles used to produce the color of the dye solution may also be dispersed in a dielectric solvent or solvent mixture. These pigment particles are preferably uncharged. If the pigment particles used to produce the color of the dye solution are charged, they preferably carry an opposite charge to the charged pigment particles. If both types of pigment particles carry the same charge, they should have different charge densities or different electrophoretic mobility. In either case, the dye or pigment used to produce the color of the dye solution must be chemically stable and compatible with the other components of the electrophoretic fluid.

The charged pigment particles can be positively or negatively charged. It may be an organic or inorganic pigment such as TiO ₂ , phthalocyanine blue, phthalocyanine, bis-anisidine aniline yellow, bis-anisidine aniline AAOT yellow, quinacridone, azo, rose, available from Sun Chemical The company's enamel pigment series, Hansa Yellow G particles from Kanto Chemical or Carbon Lampblack from Fisher. The particles should have acceptable optical characteristics and should not be swollen or softened by the dielectric solvent or solvent mixture and should be chemically stable. The resulting fluid must also be stable under normal operating conditions to prevent settling, emulsifying or flocculation.

Suitable electrophoretic display fluids can be made by any of the well known methods including milling, milling, milling, microfluidization, and ultrasonic techniques.

The settling or emulsifying of the pigment particles can be reduced by microencapsulating the particles in a suitable polymer to match the specific gravity of the dielectric solvent or solvent mixture. The microencapsulation of the pigment particles can be accomplished chemically or physically. Typical microencapsulation methods include interfacial polymerization, in situ polymerization, phase separation, coacervation, electrostatic coating, spray drying, fluidized bed coating, and solvent evaporation. Microencapsulation methods as disclosed in U.S. Patent Application Serial No. 10/335,210 (corresponding to WO 03/58335), 10/335,051 (corresponding to WO 03/57360) and 10/632,171 (corresponding to WO 04/12001) are also Where appropriate, the entire contents of which are incorporated herein by reference.

The charged pigment particles, the dye solution, and the color enhancement layer can be any color combination. However, in the context of the present invention, if the charged pigment particles are white, the dye solution is preferably a deep neutral color such as black, approximately black, dark gray, gray or dark green for better visual image contrast. For a gray/white combination, the electrophoretic fluid can comprise charged white titanium oxide (TiO ₂ ) particles dispersed in a gray dye solution. Black dyes or pigments such as Pylam Spirit Black and Fast Spirit Black from Pylam Products, Arizona, Sudan Black B from Aldrich, Thermoplastic Black X-70 from BASF, or insoluble black pigments such as carbon black. It can be used to produce the gray color of the dye solution. Another method of producing a gray dye solution is to use a dye or mixture of pigments such as cyan, yellow and magenta dyes or pigments dissolved in a dielectric solvent or solvent mixture.

There are many possibilities for other colored electrophoretic fluids. For subtractive color systems, the charged particles can be dispersed in a cyan, yellow or magenta dye solution. The cyan, yellow or magenta color can be produced via the use of a dye or pigment. For additive color systems, the charged particles can be dispersed in a red, green or blue dye solution that is also produced via the use of a dye or pigment.

As described above, Figures 3A-3D illustrate a reflective display of the first particular embodiment of the present invention. For exemplary purposes of the diagram, it is assumed that the charged pigment particles are white with a positive charge, the dye solution is gray, and the color enhancement layer is red. The first electrode layer (32) is a viewing side.

In FIG. 3A, the voltage of the first electrode layer (32) is set at a low value, and the voltage of the second electrode layer (33) is set at a high value. The positively charged white particles migrate and accumulate at the first electrode (32) because of the voltage difference. The red color of the color enhancement layer (34) is transmitted through the partitions (35). Fig. 3B is a plan view of Fig. 3A on the viewing side. Since the viewer sees both white (ie, the color of the particles) and red (the color seen through the divider) from the viewing side, a white with a slight red tint is visually perceived.

In FIG. 3C, the voltage of the first electrode layer (32) is set at a high value, and the voltage of the second electrode layer (33) is set to a low value. The positively charged white particles migrate and accumulate at the second electrode (33) because of the voltage difference. Thus, from the viewing side, the display cells will assume the color of the dye solution, i.e., gray. Fig. 3D is a plan view of Fig. 3C on the viewing side. As the viewer sees gray (ie, the color of the dye solution) and red (the color seen through the divider) from the viewing side, the visual perception is grayish red.

3A-3D illustrate the use of the present invention to obtain a two-color system (white on red, or red on white) that can be extended to white by the choice of color combinations of suitably charged pigment particles, dye solutions, and color enhancement layers. Green, white/blue and other color combinations.

In order to improve the color saturation, the shape and size of the display cell can be modified to improve the color penetration of the color enhancement layer. Figure 4 illustrates the configuration of the display cells designed for this purpose. As shown in Fig. 4, the display cell (40) is modified to have a top width ("w(1)") longer than the bottom width ("w(2)"). Thus, the display cells have a trapezoidal shape with a top parallel line that is longer than the bottom parallel line.

The ratio of w(1) to w(2) is preferably in the range of from about 1.01 to about 10, more preferably in the range of from about 1.5 to about 5. The length of w(1) is preferably in the range of from about 50 to about 250 microns, more preferably in the range of from about 80 to about 200 microns. The length of w(2) is preferably in the range of from about 5 to about 100 microns, more preferably in the range of from about 10 to about 80 microns. The thickness of the display panel (i.e., the height of the display cell, "h") is typically in the range of from about 3 to about 40 microns, preferably in the range of from about 10 to about 30 microns.

Therefore, the partition or partition wall (45) has a trapezoidal shape in which the top parallel line is shorter than the bottom parallel line. The top width ("w(3)") of the dividers is shorter than the bottom width ("w(4)") of the dividers. The ratio of w(3) to w(4) is preferably in the range of from about 0.99 to about 0.1, more preferably in the range of from about 0.7 to about 0.2. In general, the length of w(3) is preferably in the range of from about 2 to about 40 microns, more preferably in the range of from about 5 to about 30 microns. The length of Ww4) is preferably in the range of from about 10 to about 100 microns, more preferably in the range of from about 20 to about 60 microns.

Figures 5A and 5B illustrate a reflective display of the present invention having the cell configuration shown in Figure 4. For illustrative purposes, it is assumed that the charged pigment particles are white with a positive charge, the dye solution is gray, and the color enhancement layer (54) is red. The first electrode layer (52) is a viewing side.

Figure 5A is a cross-sectional view of the display panel of the configuration shown in Figure 4 and Figure 5B shows the top view.

In Fig. 5A, when the positively charged particles migrate and accumulate in the first electrode layer (52) as shown in cell X, the visual viewer perceives a white with a slight red hue from the viewing side. However, as the charged particles migrate and accumulate in the second electrode layer (53) as shown in cell Y, the colors seen from the cell top opening will have different chromaticities. For example, the color seen in the central region ("a(1)") is the color of the dye solution (ie, gray) and in the region surrounding the central region ("a(1)") ("a(2)")) The color seen will be the composite or medium toning of the color of the dye solution and the color of the color enhancement layer. In the illustrated example, the color of the area "a(2)" near the central area "a(1)" will be more complex or medium tones of gray and red, and away from the central area "a(1) The color of the area "a(2)" will be less complex or medium tones of gray and red. However, visually from the viewing side, the cell Y is aware of a red with gray.

II. Alternative design for reflective displays

An alternative design for a reflective display is depicted in Figure 6A. In this design, the color enhancement layer is omitted. Instead, the display cell is formed from a colored material. For display panels based on microcups, the microcups may be formed from any of the materials described above that have a dye or pigment or a mixture of dyes or pigments dissolved or dispersed therein. Suitable dyes and pigments are also as described above.

Figure 6B is a top plan view of the reflective display of Figure 6A. When the reflective display is an electrophoretic display, the operation of this alternative design is similar to that described in Figures 3A-3D.

For the exemplary purposes of the diagram, it is assumed that the charged pigment particles are white with a positive charge, the dye solution is gray, and the cell system is formed of a red material. The first electrode layer (62) is a viewing side.

When the voltage of the first electrode layer (62) is set at a low value and the voltage of the second electrode layer (63) is set at a high value, the positively charged white particles migrate and accumulate at the first electrode due to the voltage difference. (62). In this case, the viewer sees the red color of the partition wall of the display panel and the white color of the charged pigment particles from the viewing side. As a result, a white with a slight red hue is visually perceived from the cell X.

When the voltage of the first electrode layer (62) is set at a high value and the voltage of the second electrode layer (63) is set to a low value, the positively charged white particles migrate and accumulate at the second electrode due to the voltage difference. (63). Thus, from the viewing side, the display panel will assume the color of the dye solution, ie gray. However, since the viewer sees the gray color of the dye solution and the red color of the partition wall from the side of the viewing side, a reddish color is visually perceived from the cell Y.

In a specific embodiment of the design, the second electrode layer (63) may have a reflective surface. Alternatively, a reflector (not shown) may be placed between the display panel and the second electrode layer (63). Alternatively, if the second electrode layer is transparent or translucent, the reflector can be placed after the second electrode layer (63).

This alternative design can also provide a two-color system by selecting a combination of appropriately charged pigment particles, a dye solution, and a color that displays the color of the cell structure as described.

7A and 7B illustrate this alternative display having an alternative design of the novel display cell configuration of FIG. For demonstration purposes, it is assumed that the charged pigment particles are white with a positive charge, the dye solution is gray, and the color of the display cell structure including the partition wall (75) is red. The first electrode layer (72) is a viewing side.

Figure 7A is a cross-sectional view of a display panel having the configuration illustrated in Figure 4 and Figure 7B is a top view.

In Fig. 7A, when the positively charged particles migrate and accumulate in the first electrode layer (72) as shown by cell X, the visual viewer can perceive a white with a slight red tint from the viewing side. However, when the positively charged particles migrate and accumulate in the second electrode layer (73) as indicated by cell Y, the colors seen from the top opening of the cell will have different chromaticities. For example, the color seen in the central region ("a(1)") is the color of the dye solution (ie, gray) and in the region surrounding the central region ("a(1)") ("a(2)")) The color seen will be the composite or medium toning of the color of the dye solution and the color of the displayed cell structure. In the illustrated example, the color of the region "a(2)" near the central region "a(1)" will be a composite of more gray and less red or medium tones, and away from the region "a (1) The color of the area "a(2)" will be a combination of less gray and more red or medium tones. However, visually from the viewing side, the cell Y is perceived as a grayish red.

III. Another alternative design for reflective displays

Another alternative design is depicted in Figure 8A. In this design, the color enhancement layer shown in Fig. 1 is also omitted. Instead, the color enhancement layer (84) is aligned printed or laminated on the top surface of the dividing wall (85). Figure 8B is a top plan view of the design of Figure 8A.

The openings showing the cells or the regions corresponding to the cell openings are not covered by the color enhancing layer.

The color enhancement layer (84) can be coated with a shadow mask by, for example, printing, stamping, photolithography, vapor deposition or sputtering. Depending on the material of the color enhancing layer and the method used to deposit the color enhancing layers, the thickness of the layer can vary from about 0.005 microns to about 10 microns, preferably from about 0.01 microns to about 5 microns.

In one embodiment, the thin colored layer can be transferred to the top surface of the dividing wall (85) by a lithographic rubber roller or stamp. After the transferred paint or ink has hardened, it is then filled to show the cells. In this case, the color enhancing layer must be resistant to the electrophoretic fluid and the solvent used to seal the composition, if applicable.

In another specific embodiment, the color enhancement layer may be aligned on the partition wall by a photolithographic etching method, wherein the photolithographic etching method may illuminate the photosensitive color material on the top surface of the partition wall and align through the reticle. Perform a visual exposure. The photosensitive color material can be a positive or negative resist. When a positive resist is used, the reticle should have openings corresponding to the display cell regions. In this case, the photosensitive coloring matter showing the cell region (exposed) can be removed with the developer after exposure.

If a negative resist is used, the reticle should have an opening corresponding to the top surface of the partition. In this case, the photosensitive coloring matter showing the cell region (unexposed) can be removed as a developer after exposure. The solvent used to coat the coloring matter and the developer used to remove the substance should be carefully selected so as not to erode the display cell structure.

Alternatively, a colorless photosensitive ink suction layer may be applied to the top surface of the partition wall and then exposed through the reticle. If a positive photosensitive latent ink absorbing layer is used, the reticle should have an opening corresponding to the top surface of the dividing wall. In this case, after the exposure, the exposed areas become ink absorbing or viscous, and the color enhancement layer can be formed on the exposed areas (the top surface of the partition wall) after applying the color ink or toner to these areas. Alternatively, a negative photosensitive ink can be used to draw the layer. In this case, the reticle should have openings corresponding to the display cells, and after exposure, the exposed areas (the display cell areas) become hard, and the color enhancement layer can coat the color ink or toner. After these areas are formed on the unexposed areas (the top surface of the partition wall). The color enhancement layers can be post cured by heat or a full sheet exposure to improve film integrity and physico-mechanical properties.

In another embodiment, the color enhancing layer can be applied by means of screen printing or lithographic printing, in particular in the form of waterless lithographic printing.

It should be noted that if there are other layers (such as a sealing layer or an adhesive layer) between the top surface of the partition wall and the first electrode layer (82), the color enhancement layer may be aligned on the top surface of the corresponding partition wall by any of the above methods. Regional office.

In a particular manifestation of this design, the color enhancement layer (84) itself may have reflective features. Alternatively, the spacer layers can have reflective features. Additionally or alternatively, a reflector is present between the display panel and the second electrode layer (83). The second electrode layer may also have a reflective surface or a reflector placed after the second electrode layer.

For the purpose of the graphic representation, it is assumed that the charged pigment particles are white with a positive charge, the dye solution is gray, and the top surface of the separated cell contains a red color enhancement layer. The first electrode layer (82) is a viewing side.

When the voltage of the first electrode layer (82) is set at a low value and the voltage of the second electrode layer (83) is set at a high value, the positively charged white particles migrate and gather at the first because of the voltage difference. Electrode (82). In this case, the viewer sees both the red color of the color enhancement layer (84) and the white color of the positively charged pigment particles from the viewing side. As a result, a white with a slight red hue is visually perceived from the cell X.

When the voltage of the first electrode layer (82) is set at a high value and the voltage of the second electrode layer (83) is set to a low value, the positively charged white particles migrate and gather in the second due to the voltage difference. Electrode (83). Thus, from the viewing side, the display panel will assume the color of the dye solution, ie gray. However, since the viewer sees the gray and red color enhancement layer (84) of the dye solution from the viewing side, a grayish red color is visually perceived from the cell Y.

This alternative design can also provide a two-color system by selecting a combination of suitable charged pigment particles, a dye solution, and a color enhancement layer as described.

Figures 9A and 9B illustrate such a reflective display having an alternative design of the novel display cell configuration of Figure 4. For demonstration purposes, the charged pigment particles are again white and positively charged, the dye solution is gray, and the color of the color enhancement layer (94) is red. The first electrode layer (92) is a viewing side.

Figure 9A is a cross-sectional view of a display panel having the configuration illustrated in Figure 4 and Figure 9B is a top view.

In Fig. 9A, when the positively charged particles migrate or accumulate in the first electrode layer (92) as shown by cell X, the visual viewer can perceive a white with a slight red hue from the viewing side. However, when the positively charged particles migrate or accumulate in the second electrode layer (93) as indicated by cell Y, the color shown from the top opening of the cell will have a gray of different chromaticity. However, due to the red color enhancement layer, the cell Y is visually perceived from the viewing side to a grayish red color.

IV. Reflective direct drive display

The reflective display of the present invention is particularly suitable for use in direct drive (or segment) displays. Figure 10 is an illustration of a direct drive display of the present invention. Using either of the three specific specific manifestations described above, the top area of the display can display a two-color system of one color combination, while the bottom area can display a two-color system of different color combinations.

Using the first specific embodiment of the present invention as an example, the top region (10a) uses a red color enhancement layer and the bottom region (10b) uses a blue color enhancement layer. Thus, the top area of the display shows a white/red combination and the bottom area shows a white/blue combination. In this example, the white charged particles are dispersed in a gray dye solution.

Although the invention has been described in some detail for the purpose of clarity of the invention, it will be understood that modifications and modifications may be made within the scope of the appended claims. It should be noted that there are many alternative ways of performing the methods and apparatus of the present invention. Therefore, the present invention is to be considered as illustrative and not restrictive, and the invention is not limited by the details provided herein, but may be modified within the scope and equivalents of the appended claims.

10. . . Display panel

11. . . Display cell

12. . . First electrode layer

13. . . Second electrode layer

14. . . Color enhancement layer

15. . . Partition wall

20. . . Microcup

twenty one. . . Non-conductive substrate layer

twenty two. . . Display fluid

twenty three. . . Polymeric sealing layer

32. . . First electrode layer

33. . . Second electrode layer

34. . . Color enhancement layer

35. . . Separate road

40. . . Display cell

45. . . Separator or dividing wall

52. . . First electrode layer

53. . . Second electrode layer

54. . . Color enhancement layer

55. . . Partition wall

62. . . First electrode layer

63. . . Second electrode layer

65. . . Partition wall

72. . . First electrode layer

73. . . Second electrode layer

75. . . Partition wall

82. . . First electrode layer

83. . . Second electrode layer

84. . . Color enhancement layer

85. . . Partition wall

92. . . First electrode layer

93. . . Second electrode layer

94. . . Color enhancement layer

95. . . Partition wall

10(a). . . Top area

10(b). . . Bottom area

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view showing the design of a reflective display of the present invention.

Figure 2 illustrates a typical microcup display panel.

3A-3D illustrate the design of a reflective display of the present invention.

Figure 4 illustrates a display cell configuration suitable for use in the present invention.

Figures 5A and 5B illustrate a reflective display having the display cell configuration of Figure 4.

6A and 6B illustrate an alternative design of a reflective display of the present invention.

7A and 7B illustrate another reflective display having the display cell configuration of FIG.

8A and 8B illustrate another alternative design of the reflective display of the present invention.

Figures 9A and 9B illustrate another reflective display having the display cell configuration of Figure 4.

Figure 10 illustrates a reflective direct drive (segment) display of the present invention.

10. . . Display panel

11. . . Display cell

12. . . First electrode layer

13. . . Second electrode layer

14. . . Color enhancement layer

15. . . Partition wall

Claims (12)

A reflective display comprising: a) a first electrode layer on a viewing side; b) a second electrode layer on a non-viewing side; c) a display panel sandwiched between the first electrode layer and the second electrode layer, and the display The panel comprises a display fluid separated by a partition wall or a partition, wherein the partition walls or partitions are transparent, translucent, light transmissive or semi-transparent; and d) a color enhancement layer between the display panel and the second electrode layer Wherein the color enhancement layer is an adhesive layer. The reflective display of claim 1, wherein the second electrode layer has a reflective surface. The reflective display of claim 1, wherein the color enhancement layer is formed of a polymeric material. The reflective display of claim 1, wherein the display panel comprises a display cell array having a trapezoidal shape with a top parallel line longer than a bottom parallel line. The reflective display of claim 1, which is a reflective segment display, wherein the first electrode layer is a common electrode layer, and the second electrode layer is a bottom plate including segment electrodes. A reflective display according to claim 1, wherein the display panel is produced by microcup technology. The reflective display of claim 1, wherein the display flow system-electrophoretic display fluid comprises dispersed pigment particles dispersed in a dielectric solvent or solvent mixture. The reflective display of claim 7, wherein the charged pigment particles are formed of TiO ₂ . A reflective display according to claim 7 wherein the dielectric solvent or solvent mixture is colored. A reflective display according to claim 9 wherein the dielectric solvent or solvent mixture is a deep neutral color. A reflective display according to claim 10, wherein the deep neutral color is black, approximately black, dark gray, gray or dark green. A reflective display according to claim 1, wherein the display system is a liquid crystal composition.