JP2011065035A - Multicolor display panel - Google Patents

Abstract

The present invention provides a microcapsule-type electrophoretic multicolor display panel which is improved in the problems of lowering display brightness and narrowing the viewing angle and having excellent display quality uniformity.
A transparent substrate, a color filter layer, a transparent electrode layer, a microcapsule layer, an adhesive layer, and a back electrode plate are laminated in this order, and the microcapsule layer is laminated directly on the transparent electrode layer. The capsule layer is configured by dispersing microcapsules in a binder resin, and the microcapsules are obtained by encapsulating a dispersion liquid in which electrophoretic particles are dispersed in a transparent dispersion medium. The optical reflection characteristics change due to a change in electric field. In a multicolor display panel, the thickness of the color filter layer is in the range of 0.5 to 2.0 μm, and the step (thickness difference) between the pixels in the display screen is within 0.3 μm and adjacent to each other. The pixels do not overlap each other, and the top edge of each pixel is within 5.0 μm from the pixel boundary.
[Selection] Figure 3

Description

  The present invention relates to a microcapsule type electrophoretic display panel integrated with a color filter, and a set of microcapsule layers in which electrophoretic ink is enclosed in microcapsules, one of which is a transparent substrate having a color filter layer. The present invention relates to a multi-color display panel that can be improved in image quality by using a color filter suitable for this structure.

  In recent years, with the development of information equipment, information display has been made in various forms. As a display panel for variable information, a liquid crystal using a CRT (cathode ray tube) or a backlight is mainly used. However, light-emitting displays such as CRTs and backlight-type liquid crystal displays are not suitable for long-term use, which can cause eye strain that can cause significant eye fatigue and keep reading documents etc. for a long time. .

  In addition, a liquid crystal display of a type that does not use a backlight has a problem that the darkness of the screen due to the use of a polarizing plate appears remarkably and the visibility is poor. Furthermore, the display images on these displays do not have memory characteristics, and the display images disappear at the same time as the electrical energy supply is stopped. There is a need for a device that is less likely to cause fatigue on the eyes even when used for a long time, has good visibility, consumes less power, and has image memory properties.

  Therefore, as a reflective display device with a small eye load, for example, as disclosed in Patent Document 1, a display panel having a pair of opposed electrodes and an electrophoretic display layer provided between the electrodes is provided. It has been proposed as an electrophoretic display panel. Since this electrophoretic display panel displays characters and images by reflected light, as with the printed paper, it is suitable for work that keeps the screen looking for a long time with little load on the eyes.

  This electrophoretic display panel is based on the principle that an image can be displayed by moving charged particles by applying a voltage to a dispersion liquid in which charged particles are dispersed to change an electric field. Among electrophoretic display panels, microcapsule-type electrophoretic display panels in which colored charged particles are enclosed in microcapsules and the microcapsules are arranged between a pair of opposing electrodes are low driving voltage, high flexibility, etc. Has been commercialized and further developed.

  In addition to the displays of portable information devices such as so-called PDAs (Personal Digital Assistants) and electronic books that will become more widespread in the future, printed materials such as newspapers, books, magazines, and posters, as well as hardware output from printers to paper This electrophoretic panel is suitable for replacing a copy with a display display. The electrophoretic panel generally has a two-color display mainly for monochrome display because of its structure. However, in order to display the above-mentioned magazines and color prints, a multicolor display has recently been required.

  In order to make this electrophoretic panel multi-colored, two or more types of multi-color electrophoretic particles are used. For example, in Patent Document 2, patterning is performed by a photolithography method, and in Patent Document 3, in addition to the photolithography method. A technique for disposing electrophoretic particles in predetermined pixels using an inkjet method is disclosed. Further, Patent Document 4 discloses a display panel capable of displaying a plurality of colors by forming a cell frame that accommodates microcapsules in advance and securely installing a plurality of microcapsules at desired positions. However, disposing multi-color microcapsules in predetermined pixels has a lot of processes and complicated technical difficulties as compared with a normal photoresist or the like.

  For this reason, Patent Document 5 discloses a method capable of multi-color display by attaching a color filter substrate on a black and white electrophoretic display panel so that the positional accuracy between the microcapsules and the pixels is not required. However, in this method, a separate color filter substrate is pasted on a monochrome electrophoretic display panel, which is a reflective display panel. There has been a problem that the productivity is low because the brightness is lowered and it is difficult to bond the color filter substrate. Furthermore, since there is a distance between the color filter layer and the electrophoretic display layer, color parallax occurs depending on the viewing angle, and the advantage of electronic paper that there is no influence of the viewing angle is lost.

  Therefore, the present inventors have found that the brightness of the display and the viewing angle can be improved by directly laminating the microcapsule ink on the transparent electrode layer of the color filter. However, the influence of the change in the thickness of the color filter layer on the reflection density becomes larger. The coating liquid in which the microcapsules are dispersed has a very high thixotropic property (hereinafter abbreviated as thixotropic property). Therefore, non-uniform coating unevenness once generated due to the base unevenness when the coating liquid is applied is not flattened or uniform even in a state before drying. Therefore, in order to perform high-precision color display without unevenness on the entire display screen, the smoothness of the color filter on the viewing side that is the base of the transparent electrode layer that is the substrate to which microcapsules are applied is important.

Japanese Patent Publication No. 50-015115 JP 2002-365668 A JP 2003-156770 A JP 2003-295234 A JP 2003-161964 A

  The present invention has been made in view of the above circumstances, and in a multicolor display microcapsule-type electrophoretic display panel, the problems of lowering display brightness and narrowing the viewing angle are improved, and display quality is improved. An object of the present invention is to provide a multicolor display panel having excellent uniformity.

  As a result of diligent examination of the above problems, the present inventors have easily adjusted the smoothness of the color filter layer to a certain range, thereby facilitating uniform application of the microcapsule ink and less uneven density. The present inventors have found that a multicolor display panel that can be improved in quality can be obtained.

That is, the invention according to claim 1 of the present invention is a multicolor display panel configured by laminating a transparent substrate, a color filter layer, a transparent electrode layer, a microcapsule layer, an adhesive layer, and a back electrode plate in this order. The microcapsule layer is directly laminated on the transparent electrode layer, and the microcapsule layer is configured by dispersing microcapsules in a binder resin, and the microcapsules are electrophoresed in a transparent dispersion medium. A dispersion liquid in which particles are dispersed is enclosed, and the optical reflection characteristics change due to an electric field change caused by application of a voltage. The back electrode plate is an electrode plate in which pixel electrodes are arranged on a base material In the multicolor display panel
The film thickness of the color filter layer is in the range of 0.5 to 2.0 μm, the level difference (thickness difference) between the pixels in the display screen and within the pixels is within 0.3 μm, and each adjacent pixel is The multicolor display panel is characterized in that it does not overlap and the top edge of each trapezoidal pixel is within 5.0 μm from the pixel boundary.

  The invention according to claim 2 of the present invention is characterized in that the electrophoretic particles are particles having two different surface charges, one of which is a colored particle and the other is a white particle. 1 is a multicolor display panel described in item 1;

  In the multicolor display panel of the present invention, a microcapsule layer is directly formed on a transparent electrode layer on a color filter layer having a small film thickness difference and high smoothness, so that the microcapsule ink can be uniformly applied and displayed. The arrangement of the microcapsule layer and the color filter layer on the surface is very close to each other, and a multicolor display panel with improved image quality can be obtained. In addition, a multi-color display panel with little color density unevenness due to a difference in film thickness of the color filter layer in which light passes twice with a reflection type can be obtained.

  In addition, compared with a conventional display panel formed by bonding a separately prepared color filter substrate, the structure of the present invention does not include an unnecessary layer such as an adhesive between the microcapsule layer and the color filter layer. The reflected light reflected by the capsule layer passes through a minimum layer, and the display brightness is improved as compared with the conventional display panel.

  In addition, regarding the display of the microcapsule layer and the color shift of the color filter observed when the distance between the color filter layer and the microcapsule layer is increased, the parallax as described above is reduced by the proximity of the microcapsule to the color filter layer. It is not observed and the viewing angle is not pinched.

  Further, in the multicolor display panel of the present invention, the color filter layer has high smoothness, the transparent electrode layer formed thereon is formed smoothly, and the distance from the pixel electrode layer formed in the pair is easy. Therefore, since a uniform voltage is applied to the microcapsules, there is no display unevenness and the image display quality is improved.

Schematic explaining the structure which concerns on one Embodiment of the multicolor display panel of this invention in a cross section. The schematic diagram explaining the structure which concerns on one Embodiment of the multicolor display panel of this invention in an expanded cross section. The schematic diagram of the expanded section of an example of the color filter which comprises the multicolor display panel of this invention. FIG. 3 is an enlarged plan view illustrating an embodiment of a color filter constituting the multicolor display panel of the present invention.

  The multicolor display panel of the present invention will be described in detail below based on one embodiment thereof.

FIG. 1 is a schematic diagram illustrating a configuration example of a multicolor display panel according to an embodiment of the present invention in cross section, and FIG. 2 is a schematic diagram illustrating an enlarged cross section thereof. As shown in FIG. 1 and FIG. 2, the multicolor display panel of the present invention comprises a color filter layer (2) and a transparent electrode layer (4) on a transparent substrate (1).
And a microcapsule having an optical reflection characteristic that changes due to an electric field change by applying a voltage, wherein a dispersion liquid in which electrophoretic particles are dispersed in a transparent dispersion medium is enclosed on the transparent electrode layer (4). 5) a color filter with a microcapsule in which a microcapsule layer (10) dispersed in a binder resin (11) is directly laminated, and a pixel electrode through the adhesive layer (16) on the microcapsule layer (10). It is a cross-sectional structure in which a back electrode plate made of a back substrate (50) provided with (30) is laminated.

  Although not shown, a surface smoothing layer that is overcoated only with a binder resin is provided on the microcapsule layer (10) to reduce the unevenness of the microcapsules (5) as necessary.

  Transparent substrates (1) include glass plates such as soda lime glass, low alkali borosilicate glass, non-alkali aluminoborosilicate glass, polyethylene terephthalate (PET), polycarbonate, polyimide, polyethylene naphthalate, polyethersulfone, acrylic resin A resin plate such as polyvinyl chloride is used.

  In the multicolor display panel of the present invention, the planar pattern shape of the color filter layer (2) is not particularly limited, and a suitable shape can be used as appropriate, for example, a fine band (striped) filter segment. Are arranged in parallel or intersecting with each other, or fine filter segments are arranged in a certain arrangement in the vertical and horizontal directions. For example, a pixel configuration combining RGBW as shown in FIG. 4 is often used, but the present invention is not limited to this. The color filter layer (2) used in the present invention is provided with a plurality of colored patterns, and colored pixels are arranged in each of the pixel regions. The colored pixels are used to color the transmitted light for each pixel, and are generally three colors of red (R), green (G), and blue (B) corresponding to the three primary colors of light, or yellow (Y) and magenta ( The colored pixels of the three primary colors M) and cyan (C) are arranged. Here, W is a transparent resin used for a photo spacer or the like, which can be combined with colored pixels so that the brightness can be increased by using more reflected light. In general, a black matrix is not used for the color filter layer constituting the panel.

  In the multicolor display panel of the present invention, as shown in FIG. 3, the cross-sectional shape of the color filter layer (2) is adjusted to a certain shape from the applicability of the microcapsule ink and the image display characteristics. The film thickness of the color filter layer is 0.5 to 2.0 μm, preferably 0.7 to 1.3 μm. In the multicolor display panel of the present invention, since light passes through the color filter layer twice, the film thickness is reduced compared to the transmissive type in order to ensure lightness, or color characteristics with high transmittance. A colored resin having is used. If the film thickness is less than 0.5 μm, the required coloring density and the adhesion to the transparent substrate cannot be balanced. Further, when the film thickness exceeds 2.0 μm, there is a problem that the film thickness variation due to development or the like cannot be suppressed.

  The level difference (film thickness difference) between the pixels in the display screen is set to be within 0.3 μm, preferably 0.1 μm. When the level difference between the pixels exceeds 0.3 μm, the color density difference is recognized, and unevenness such as undulation occurs on the application surface of the microcapsule ink, which may affect the image display. This film thickness difference can be controlled by resist ink composition, exposure conditions, development conditions, and the like.

In order to avoid contrast and color mixing in a color filter for a liquid crystal display panel using a backlight, a black matrix (BM) is used between pixel patterns, and light leakage is avoided even when no BM is used. The pixels adjacent to each other are overlapped. Therefore, when the edge of the pixel rises and its height exceeds 0.3 μm, the microcapsule ink is biased and the uniformity of the coated surface is affected. Therefore, in the color filter according to the present invention, pixels do not overlap each other. The final cross-sectional shape of each pixel is usually trapezoidal, but adjacent pixels do not overlap with each other at the trapezoidal bottom edge and do not overlap each other, and the top edge of each trapezoidal pixel Is within 5.0 μm from the pixel boundary, preferably within 3.5 μm. With such a cross-sectional shape, there is no swell of pixels, there is no unevenness of the microcapsule ink, it is possible to suppress the occurrence of image unevenness that appears as surface undulations, and the utilization efficiency of reflected light A display panel with good brightness and high brightness can be obtained.

  In general, the color filter layer is manufactured by applying a colored photosensitive resin or a transparent photosensitive resin, in which a coloring agent such as a pigment or a dye is dispersed and mixed in a photosensitive resin, onto a glass substrate by a spin coating method or a spinless coating method. After applying to a uniform thickness and drying and removing excess solvent, an ultra-high pressure mercury lamp is used for proximity exposure (proximity exposure) through a photomask of the desired shape for this resist film by photolithography. Then, irradiate with active energy rays, cure (negative type) or increase alkali solubility (positive type), repeat the necessary number of steps to develop and post-bake by removing the part that dissolves with alkaline solution etc. Is done. In the present invention, the production method is not particularly limited.

  The color filter layer (2) is provided with a transparent electrode layer (4) after polishing and flattening the surface as necessary. What can be used as the transparent electrode material is a conductive oxide having transparency such as indium oxide, tin oxide and zinc oxide such as ITO. Conventional techniques such as vapor deposition, sputtering, and CVD can be used to form the transparent electrode.

  The outline of the display principle of the color filter with microcapsules constituting the multicolor display panel of the present invention will be described below.

  As shown in FIG. 2, the pixel electrode (30) on the back substrate (50) is connected to a switching element (not shown) of each pixel electrode, and between the transparent electrode layer (4). Positive and negative voltages can be applied. In order to display an image, the pixel electrode (30) is usually connected to a power source having a circuit configuration of an active matrix drive system. When a voltage is applied to the pixel electrode (30), the electric field applied to the microcapsule layer (10) varies. When the pixel electrode (30) is positive, the negatively charged particles in the microcapsule (5) move to the back pixel electrode (30) side, and the positively charged particles are It moves to the transparent electrode layer (4) side. Similarly, when the pixel electrode (30) becomes a negative electrode, the positively charged particles move to the pixel electrode side, and the negatively charged particles move to the transparent electrode layer (4) side. Here, for example, if the black particles are positively charged and the white particles are negatively charged, the display color becomes the color of the particles moved to the transparent electrode layer (4) side of the front surface. The desired character or image can be displayed in color by passing the colored pattern of the color filter layer where the reflected light is reflected and the reflected light is opposed.

  Next, materials and members used for the multicolor display panel of the present invention will be further described.

  The microcapsule (5) used for forming the color filter with microcapsules is composed of colored particles (6), white particles (7), a transparent dispersion medium (8), and a microcapsule shell (9).

  In general, microcapsules used in microcapsule-type electrophoretic display panels are refined by a sieving method or a specific gravity separation method, and have an average particle size of 30 to 100 μm. On the other hand, the proportion of microcapsules having a particle size within 10 μm before and after exceeds at least 50%. The microcapsules used in the multicolor display panel of the present invention are adjusted to have the particle size distribution described above in the microcapsule layer.

  For the microcapsule dispersion, an aqueous solvent such as alcohol is used, and water is used if there is no particular problem.

  The transparent dispersion medium (8) is selected from an insulating liquid capable of charging charged particles well and stably, that is, an organic solvent substantially insoluble in water. For example, long-chain alcohol solvents such as dodecanol and undecanol, polycarbon ketones such as dibutyl ketone and methyl isobutyl ketone, aliphatic hydrocarbons such as pentane, hexane and octane, and alicyclic groups such as cyclohexane and methylcyclohexane Benzenes with long-chain alkyl groups such as hydrocarbons, benzene, toluene, xylene, hexylbenzene, butylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, etc. Aromatic hydrocarbons, halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and 1,2-dichloroethane, and various oils such as silicone oil and olive oil, or a mixture thereof. Be mentioned

  As the black electrophoretic particles as the colored particles (6), in addition to black pigments such as aniline black and carbon black, fine powders such as glass or resin, and composites thereof are used. In the multicolor display panel of the present invention that performs multicolor display using a color filter, normally, black particles using carbon black are used. The white electrophoretic particles as the white particles (7) use known white inorganic pigments such as titanium oxide, silica, alumina and zinc oxide, organic compounds such as vinyl acetate emulsion, and composites thereof. .

  The colored particles (6) and the white particles (7) may have a desired surface charge by treating the surface of the particles with various surfactants, dispersants, organic and inorganic compounds, metals, etc. as necessary. Not only can be imparted, but also the dispersion stability in the transparent dispersion medium (8) can be improved.

  Dispersion A in which colored particles (6) and white particles (7) are dispersed in a transparent dispersion medium (8) is a phase separation method such as a mixed coacervation method, an interfacial polymerization method, an in-situ method, and a solution dispersion cooling method. Etc., and encapsulating in microcapsules using a known method. The shell (9) of the microcapsule is, for example, a rubber or gelatin film. As a material for forming the microcapsule, a material that transmits light sufficiently is preferable. Specifically, urea-formaldehyde resin, melamine-formaldehyde resin, polyester resin, polyurethane resin, polyethylene resin, polystyrene resin, polyamide resin, acrylic resin are preferable. Acid ester resin, methacrylic ester resin, vinyl acetate resin, rubber, gelatin and the like can be mentioned. These may be used alone or in combination of two or more.

  A microcapsule dispersion is prepared by mixing a thickener, a surfactant, a binder resin (11), and the like with a microcapsule dispersion in which microcapsules having different particle size distributions are dispersed. For the binder resin (11) of the microcapsule ink, a dielectric resin such as polylactic acid, phenol resin, polypropylene resin, acrylic resin, or urethane resin is used. When two or more kinds of microcapsule inks are mixed and then mixed, in order to prevent a change in ink density after mixing, the density of the inks to be mixed is adjusted to be equal.

  As described above, the microcapsule layer (10) is a transparent substrate (1) comprising a glass substrate or a resin substrate on which the color filter layer (2) and the transparent electrode layer (4) are provided in advance as described above. It is directly coated on the transparent electrode layer (4). The coating can be performed using a coating apparatus such as a screen printing method, a micro gravure coater, a kiss coater, a comma coater, a die coater, a bar coder, or a curtain coater. In the present invention, a slot die coater is preferably used. it can.

  Since the surface of the microcapsule layer (10) formed as described above is uneven, the distance between the electrodes sandwiching the microcapsule is difficult to be constant. Therefore, it is preferable to apply a surface smoothing ink on the microcapsule layer (10) to form a surface smoothing layer. By forming the surface smooth layer, the adhesive can be directly applied onto the surface smooth layer. This is because when the adhesive is directly applied without a surface smoothing layer, if there are uncoated portions such as pinholes in the microcapsule layer (10), the adhesive directly touches the transparent electrode layer (4) on the color filter side, It can be avoided that the dielectric constant changes and it becomes difficult to apply a voltage to the microcapsule, resulting in an unclear display.

  The surface smoothing ink is obtained by dispersing a resin in a solvent as a binder. As the binder component, a resin having the same dielectric constant as that of the binder resin component used in the microcapsule ink or the binder component used in the adhesive layer is preferable. Especially, it is the most preferable that it is the same as the binder resin component used for the microcapsule ink and the adhesive layer, and the binder resin component of the surface smoothing ink is also the same. When resins having different dielectric constants are used, resins having different dielectric constants are laminated between the electrodes, and the thickness of each resin varies depending on the size of the microcapsule in the portion. This is because the voltage applied to the microcapsules is difficult to be uniform over the entire screen due to the difference in dielectric constant of each resin.

  As the solvent for the surface smoothing ink, those used for the microcapsule ink can be used, but other aqueous solvents such as alcohols may be used. The surface smoothing ink is applied using a coating apparatus such as a curtain coater or a slot die coater. The coating method of scraping off the coating liquid such as blade coating cannot be used because it bursts the microcapsules in the microcapsule layer.

  The thickness of the surface smoothing layer is preferably 10 to 30 μm. When the thickness is 10 μm or less, the unevenness of the microcapsule surface is not smooth. On the other hand, if it is 30 μm or more, the distance between the electrodes increases, which causes the drive voltage to increase.

  As described above, the surface smoothing layer is formed and the solvent is sufficiently evaporated to form a color filter with microcapsules. The color filter with microcapsules and the back electrode plate with pixel electrodes on the back substrate are bonded to each other through the adhesive layer while aligning the color pattern of the color filter (pixels) and the back electrode electrodes. By laminating, the electrophoretic multicolor display panel of the present invention is completed.

  What can be used as the adhesive is preferably a synthetic resin adhesive such as a urethane resin adhesive or an acrylic resin adhesive. In particular, an adhesive using a high dielectric resin is preferable.

  The adhesive can be applied directly on the microcapsule layer or the pixel electrode. However, in the manufacturing method of the present invention, the adhesive is formed on a resin release substrate in which a conductive layer is formed between the silicon film and the resin substrate. It is preferable to apply an adhesive using the same components as the binder resin used in the microcapsule ink and apply it as an adhesive sheet. By using an adhesive with the same components as the binder resin used in the microcapsule ink, the affinity at the interface of the resin is increased, peeling does not occur easily, and the dielectric constant is similar, so it is applied to the microcapsule. An advantage is that the applied voltage tends to be constant in terms of surface.

Moreover, by using a resin release substrate in which a conductive layer is formed between a silicon film and a resin substrate, a multilayer substrate in which the above adhesive sheet is laminated on a color filter with microcapsules, a so-called color filter electrophoretic display type front plate Drive evaluation and quality confirmation. Note that the conductive layer here does not require transparency, and may be a thin film formed by vapor deposition and electrodeposition of a metal such as copper or aluminum, or a film formed by applying a conductive polymer.

  Specific examples of the present invention will be described below.

<Example 1>
Disperse titanium oxide powder (white particles) with an average particle diameter of 3 μm coated with a polyethylene resin and carbon black powder (black particles) with an average particle diameter of 4 μm surface-treated with alkyltrimethylammonium chloride in tetrachloroethylene as a transparent dispersion medium. Dispersion A was obtained. In this case, the white particles are negatively charged and the black particles are positively charged.

  Next, an aqueous solution in which gelatin and sodium polystyrene sulfonate are dissolved in water is prepared, mixed with dispersion A, adjusted to a liquid temperature of 40 ° C., and stirred with a homogenizer while maintaining the liquid temperature. An emulsion was obtained.

  Next, the obtained O / W emulsion and an aqueous solution in which gum arabic was dissolved in water were mixed using a dispenser at 40 ° C., and the pH of the solution was adjusted using acetic acid while maintaining the liquid temperature at 40 ° C. Was adjusted to 4, and microcapsules having gelatin-gum arabic as a shell material were formed by a complex coacervation method.

  Further, after the liquid temperature was lowered to 5 ° C., a 37 mass% formalin solution was added to harden the wall material of the microcapsule shell, and dispersion in which white particles (titanium oxide particles) and black particles (carbon black particles) were dispersed A microcapsule enclosing the liquid A was obtained.

  The microcapsules thus obtained were sieved, and the particle diameters were adjusted so that the average particle diameter was 40 μm and the ratio of microcapsules having a particle diameter of 30 to 50 μm was 50% or more.

  Next, an aqueous dispersion of microcapsules having a solid content of 40% by mass was prepared using the microcapsules having the same particle size as a solid content. The aqueous dispersion, a urethane binder having a solid content of 25% by mass (CP-7050, manufactured by DIC Corporation), a surfactant, a thickener, and pure water were mixed to prepare a microcapsule ink.

  On the other hand, a color filter was prepared by the following method. Here, all parts are parts by mass. First, 50 parts of butyl methacrylate, 20 parts of methyl methacrylate and 30 parts of acrylic acid were copolymerized using cyclohexanone as a solvent to prepare an acrylic resin.

  An acrylic resin solution was prepared so that the solvent was in a ratio of 47 parts with respect to 25 parts of this acrylic resin, and 20 parts of a red pigment (Pigment Red 22) was added thereto and dispersed in a bead mill for 1 hour. Thereafter, further 4 parts of dipentaerythritol and 4 parts of hexaacrylate as photosensitive monomers and 0.3 part of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide as a photopolymerization initiator were mixed in a disper. A red photoresist material was prepared.

  This red photoresist material was spin-coated on a transparent glass substrate having a length of 400 mm × width of 320 mm and a thickness of 0.7 mm, left at room temperature for 5 minutes to smooth the film surface, and then dried at 70 ° C. for 20 minutes. A red photoresist layer was formed.

Then, as shown in FIG. 4B, this red photoresist layer is provided with six 6-inch panels with a display screen length of 97.28 mm × width 128.08 mm, as shown in FIG. 4A. A photomask corresponding to a pattern of subpixel size 151 μm × 153 μm and RGBW pixel size 302 μm × 306 μm repeated vertically and horizontally is placed at the red exposure position, and the exposure amount is measured with an ultra high pressure mercury lamp. The contact exposure was performed under the condition of 150 mJ / cm ² . After the exposure, spray development was performed for 20 seconds by spraying a 1% aqueous sodium carbonate solution at a temperature of 20 ° C. at an ejection pressure of 1 Kg / cm ² to remove the unexposed area and expose the glass substrate. After drying the glass substrate after the development treatment, the film was hardened by heating at 230 ° C. for 1 hour to obtain a red pattern having a thickness of 1.1 μm.

Next, on the glass substrate on which the red pattern is formed, a green pigment (Pigment Green 7) is used as a coloring material, and a green photoresist material prepared with the same composition as the above-described red photoresist is used. A layer was formed. Then, the same photomask as described above was moved to the position where the green pattern was to be formed, and contact exposure was performed under an exposure amount of 200 mJ / cm ² . After the exposure, spray development in which a 1% sodium carbonate aqueous solution at a temperature of 20 ° C. was sprayed at an ejection pressure of 1 Kg / cm ² was performed for 30 seconds to remove unexposed portions and expose the glass substrate. After the glass substrate after the development treatment was dried, a hardening treatment was performed by heating at 230 ° C. for 1 hour in the same manner as described above to obtain a green pattern having a thickness of 1.2 μm.

  Further, as described above, a blue photoresist layer was formed by using a blue photoresist material using a blue pigment (Pigment Blue 15: 6) as a color material. Then, a photomask similar to that described above was moved and installed at the position where the blue pattern was to be formed, closely exposed and developed, and the unexposed areas were removed to expose the glass substrate. The glass substrate after the development treatment was dried, and then hardened by heating at 230 ° C. for 1 hour in the same manner as described above to obtain a blue pattern having a thickness of 1.1 μm.

  Next, using a photosensitive acrylic resin excluding only the colored pigment, the same operation as described above was performed to obtain a W (transparent) pattern having a film thickness of 1.1 μm. The RGBW sub-pixels are formed such that adjacent pixels do not overlap and are in contact with each other at the bottom edge, and the maximum is 1.0 μm or less even when separated. The top edges were all within 3.3 μm from the pixel boundary. Further, the step (thickness difference) between the pixels and within the pixels was 0.15 μm at the maximum.

  In this way, six 6-type panels with a display screen of 97.28 mm long and 128.08 mm wide are provided on a glass substrate, the subpixel size is 151 μm × 153 μm, and the pixel size composed of RGBW is 302 μm. A substrate on which a color filter layer having a pattern of × 306 μm was formed was obtained. Next, a transparent electrode layer made of ITO having a thickness of 150 nm was formed on the entire surface of the color filter layer and the exposed glass substrate by a sputtering method without performing a polishing process.

  Next, the above-described microcapsule ink was directly applied on the transparent electrode layer on the transparent glass substrate on which the above-described color filter layer was formed, using a slot die coater. The application was performed in such a manner that the microcapsule layer had a thickness of 40 μm, the microcapsules did not overlap each other, and the microcapsules having a large particle size were pressed into the microcapsule layer. After application, the film was dried at 60 ° C. for 10 minutes to obtain a color filter with microcapsules.

Furthermore, a urethane binder (CP-7050, manufactured by DIC Corporation) having a solid content of 25 mass% is overlaid as a surface smoothing ink on the microcapsule layer of the color filter with microcapsules using a slot die coater. And dried to obtain a color filter with microcapsules with a surface smoothing layer.

  Separately, aluminum is deposited to a thickness of 100 nm as a conductive layer on one side, and further a polyester-urethane adhesive is 25 μm on the side of the release coat surface of a 50 μm-thick polyethylene terephthalate sheet on which a silicon release coat layer is provided. The adhesive sheet was adjusted by thick application.

  Next, the adhesive sheet was bonded to the color filter with microcapsules with the surface smoothing layer to obtain a color filter electrophoretic display type front plate having six 6-type display screens. In this state, a voltage was applied to the transparent electrode layer and the conductive layer to confirm driving of the microcapsule layer.

  Next, on the color filter electrophoretic display type front plate, the polyester-urethane adhesive adhesive layer is left, the 50 μm-thick polyethylene terephthalate sheet provided with a silicon release coat is peeled off, and the color filter is positioned. A back electrode plate having a pixel electrode made of ITO having a circuit configuration of an active matrix type driving method using a thin film transistor on a glass substrate as a TFT substrate having a 6-type, 6-face corresponding to a color filter, and corresponding to a color filter The multi-color display panel as a microcapsule type electrophoretic display panel with a color filter of the present invention was obtained by pasting the display screen of 6 screens into pieces.

A voltage of about 15 V is applied between the front transparent electrode and the back pixel electrode from a standard voltage / current generator (manufactured by Yokogawa Electric Corporation) to each display panel of Example 1 thus manufactured. Characteristics were evaluated. Also, using a color difference meter CR-400 (manufactured by Konica Minolta), the reflectance during color display (white display) and black display is measured, and contrast = color (white) reflectance / black Contrast was evaluated as reflectance. Furthermore, the visual brightness L ^* was measured with the same apparatus.

  As a result, the display panel of Example 1 has high brightness and can realize multicolor display with the same contrast in all of the six display panels. No image unevenness caused by uneven application of the microcapsule ink, or no difference in color density between the six panels was detected. Further, any of the display panels was capable of excellent color display with no color shift when viewed from the front and in the horizontal direction and with improved color parallax depending on the viewing angle.

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2 (RGB) ... Color filter layer 4 ... Transparent electrode layer 5 ... Microcapsule 6 ... Colored particle 7 ... White particle
DESCRIPTION OF SYMBOLS 8 ... Transparent dispersion medium 9 ... Microcapsule shell 10 ... Microcapsule layer 11 ... Binder resin 16 ... Adhesive layer 30 ... Pixel electrode
50 ... Back base material

Claims (2)

A multicolor display panel configured by laminating a transparent substrate, a color filter layer, a transparent electrode layer, a microcapsule layer, an adhesive layer, and a back electrode plate in this order,
The microcapsule layer is directly laminated on the transparent electrode layer,
The microcapsule layer is configured by dispersing microcapsules in a binder resin, and the microcapsules encapsulate a dispersion liquid in which electrophoretic particles are dispersed in a transparent dispersion medium. The optical reflection characteristics change,
In the multicolor display panel, the back electrode plate is an electrode plate in which pixel electrodes are arranged on a base material,
The film thickness of the color filter layer is in the range of 0.5 to 2.0 μm, the level difference (thickness difference) between the pixels in the display screen and within the pixels is within 0.3 μm, and each adjacent pixel is A multi-color display panel, wherein the top edges of the trapezoidal pixels are within 5.0 μm from the pixel boundary without overlapping.   2. The multicolor display panel according to claim 1, wherein the electrophoretic particles are two kinds of particles having different surface charges, one of which is a colored particle and the other is a white particle.