JP2010210856A - Image display medium, image display device, and method of driving image display medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve display contrast in an image display medium. <P>SOLUTION: In the image display medium in which particulate dispersion is sealed in a plurality of partitioned cells between two electrode substrates, the electrode substrates include a light-transmitting first common electrode 1 and second and third individual electrodes 2, 3, wherein one cell is provided with two individual electrodes, the particulate dispersion is electrophoretic liquid having three kinds of dispersion particles dispersed therein, wherein the first dispersion particle 5 has no substantial charge, the second dispersion particle 6 is an electrophoretic particle with positive charge, the third dispersion particle 7 is an electrophoretic particle with negative charge, a display layer performs a display operation by the electrophoresis of the dispersion particles by application of a voltage, and a voltage application means applying a prescribed voltage between second and third individual electrodes are provided between the first common electrode 1 and the second and third individual electrodes 2, 3 and/or between the second and third individual electrodes 2, 3 corresponding to one cell, the voltage application means performs the application so that the individual electrodes that are adjacent via a barrier rib 9 of the cell are each at the same potential. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display medium, an image display device, and an image display medium driving method. More specifically, an image display medium, an image display device, and an image display medium driving that switch an image display state and a non-display state by moving charged white or colored particles in the electric field direction based on the principle of electrophoresis. Regarding the method.

  CRTs and liquid crystal displays are widely used as terminals for displaying so-called images such as characters, still images, and moving images. They can display and rewrite digital data instantly, but it is not easy to always carry the device. In addition, since it is a self-luminous device, there are problems such as eye fatigue when working for a long time and display not being maintained when the power is turned off.

  On the other hand, when a character or a still image is distributed or stored as a document, it is recorded on a paper medium by a printer. This paper medium is widely used as a so-called hard copy. Since hard copy sees reflections due to multiple scattering, it has better visibility than a self-luminous device and is less tiring. Moreover, since it is lightweight and excellent in handling, it can be read in a free posture. However, the hard copy is discarded after it is used. Some of them are recycled, but the recycling requires a lot of labor and cost, and there are problems in terms of resource saving.

  In recent years, with the development of information equipment, information processing such as document creation has been performed on a computer, and the opportunity to read text on a display terminal has greatly increased. Under such circumstances, there is a growing need for a paper-like display medium that can be rewritten with the advantages of both display and hard copy and that is suitable for the act of reading. Recently, display media using polymer-dispersed liquid crystals, bistable cholesteric liquid crystals, electrochromic elements, electrophoretic elements, and the like are attracting attention as reflective display media that can display bright images and have memory properties. . In particular, a display medium using an electrophoretic element is excellent in terms of display quality and power consumption during display operation. For example, Patent Documents 1 and 2 disclose the principle invention.

  In a display medium using an electrophoretic element, a dispersion liquid in which a plurality of electrophoretic particles having a color different from the color of a dispersion medium is dispersed in a colored dispersion medium is enclosed between a pair of transparent electrodes. is there. In this case, the electrophoretic particles (hereinafter also simply referred to as electrophoretic particles) are charged on the surface in the dispersion medium, and the particles can be moved by forming an electric field between the transparent electrodes.

  For example, when a charge opposite to the charge of the electrophoretic particles is applied to one of the transparent electrodes, the electrophoretic particles are attracted to the electrode and deposited near the electrode, and the color of the electrophoretic particles is observed. Conversely, when the same charge as that of the electrophoretic particles is applied, the electrophoretic particles move to the opposite side, and thus the color of the dispersion medium is observed. By changing the charge on the electrode surface in this way, various displays can be performed by applying the principle of changing the observed color.

  In conventional display media using electrophoretic elements, the display color is two-color display switching based on particles of two different colors, or one type of particles and a dispersion medium colored in a different color from the particles. It was. However, in such a configuration, there is no problem in monochromatic display such as black and white, but in the case of full color display or the like, when displaying by combining the sub-pixels of the three primary colors, it is difficult to display in black and white. That is, in order to achieve both black and white display and color display, it is necessary to perform three-color display of white, black, and another color per subpixel.

  In order to solve such a problem, Patent Document 3 discloses a technique in which three subpixels of electrophoresis are used, and each subpixel includes a capsule containing three kinds of particles that are visually different. . In the technique described in Patent Document 3, the individual electrode located on the side opposite to the visual field side is composed of a plurality of electrodes, and the particles included in the subpixel are composed of particles having 1 to 3 types of hues, and the particles are dispersed. The dispersion to be made is transparent, dyed or colored. The individual electrodes are colored as necessary, or a color reflector is disposed on the back surface of the transparent individual electrode.

  Further, Patent Document 4 discloses an electrophoretic liquid in which three types of dispersed particles having different optical characteristics and charging characteristics are dispersed in a solvent, wherein the first dispersed particles have no charge and the second dispersed particles have a charge. Discloses an electrophoretic display element using an electrophoretic liquid, wherein is a positive electrophoretic particle and the third dispersed particle is an electrophoretic particle having a negative charge.

  In the electrophoretic display element described in Patent Document 4, a voltage is applied between the first electrode and the second and / or third electrode to display the second or third electrophoretic particles. By accumulating on the first electrode side in the medium, the electrophoretic particles accumulated on the first electrode side can be observed through the transparent electrode. In addition, without applying a voltage to the first electrode, a voltage is applied between the second electrode and the third electrode, so that the second and third electrophoretic particles are moved into the second electrode in the electrophoretic display medium. By accumulating on the 2nd and 3rd electrode side, the 1st dispersible particle | grains disperse | distributed in the electrophoretic display medium can be observed through a transparent electrode.

  However, no voltage is applied to the first electrode, a voltage is applied between the second electrode and the third electrode, and the second and third electrophoretic particles are moved to the second electrode in the electrophoretic display medium. When the particles are accumulated on the third electrode side, a potential difference is generated between the third electrode of a certain cell and the second electrode of an adjacent cell, and particles to be originally accumulated on the second electrode of a certain cell are A phenomenon of moving toward the second electrode of the adjacent cell was observed.

  When such a phenomenon occurs, the second and third electrophoretic particles cannot be accumulated on the second and third electrodes, so that they can be observed by being mixed with the first particles accumulated on the first electrode. Thus, it becomes difficult to display the color of the first particles neatly, resulting in a problem that the display contrast of the image display medium is lowered.

  Therefore, the present invention provides an electrophoretic display element capable of displaying three kinds of colors in one cell by preventing an electric field generated by a potential difference between individual electrodes between adjacent cells from adversely affecting the original movement of the electrophoretic particles. An object of the present invention is to provide an image display medium, an image display device, and an image display medium driving method capable of increasing the display switching speed and improving the contrast.

  In order to achieve this object, the image display medium according to claim 1 is enclosed in a plurality of cells in which a fine particle dispersion composed of at least a nonpolar solvent and particles is partitioned between two electrode substrates. The electrode substrate is composed of a light transmissive first common electrode and two second and third individual electrodes provided for one partitioned cell, and the fine particle dispersion is 3 An electrophoretic liquid in which various types of dispersible particles are dispersed, wherein the first dispersible particles are substantially free of charge, the second dispersible particles are electrophoretic particles having a positive charge, and the third dispersion The electrophoretic liquid is an electrophoretic liquid that is an electrophoretic particle having a negative charge, and is provided between the first common electrode and the second and third individual electrodes and / or the second and third electrodes corresponding to one cell. Display operation is performed by electrophoresis of dispersible particles by applying voltage between individual electrodes. In the image display medium comprising the display layer and the voltage applying means for applying a desired voltage between at least the second and third individual electrodes, the voltage applying means has the same individual electrodes adjacent to each other through the partition walls of the cells. It is applied so as to be a potential.

  According to a second aspect of the present invention, there is provided an image display apparatus according to the first aspect of the present invention, the information input means for supplying image information to the image display medium, and the power to the image display medium and information input means. Power supply means.

  According to a third aspect of the present invention, there is provided a method for driving an image display medium, wherein a fine particle dispersion composed of at least a nonpolar solvent and particles is enclosed between two electrode substrates in a plurality of cells. The substrate is composed of a light-transmitting first common electrode and two second and third individual electrodes provided for one partitioned cell, and the fine particle dispersion includes three types. An electrophoretic liquid in which dispersible particles are dispersed, wherein the first dispersible particles are substantially free of charge, the second dispersible particles are electrophoretic particles having a positive charge, and the third dispersible particles Is an electrophoretic liquid having negatively charged electrophoretic particles, and is provided between the first common electrode and the second and third individual electrodes and / or the second and third individual electrodes corresponding to one cell. A display layer that performs a display operation by electrophoresis of dispersible particles by applying a voltage between them In the driving method for switching the display of the image display medium comprising a voltage applying means for applying a desired voltage between at least the second and third individual electrodes, the voltage applying means includes adjacent individual electrodes via the partition walls of the cells. Are applied at the same potential.

  According to the present invention, in an electrophoretic display element capable of displaying three types of colors in one cell, an electric field generated by a potential difference between individual electrodes between adjacent cells is not adversely affected on the original movement of the electrophoretic particles. Accordingly, it is possible to provide an image display medium, an image display apparatus, and an image display medium driving method capable of increasing the display switching speed and improving the display contrast.

It is a section conceptual diagram (1) of an image display medium concerning the present invention. It is a section conceptual diagram (2) of the image display medium concerning the present invention. It is a section conceptual diagram (3) of the image display medium concerning the present invention. It is a section conceptual diagram (4) of the image display medium concerning the present invention. It is a section conceptual diagram (5) of the image display medium concerning the present invention. It is an example of the cross-sectional conceptual diagram of the conventional image display medium. It is an example of the electric potential simulation of the conventional image display medium. It is a cross-sectional conceptual diagram (6) of the image display medium based on this invention. It is an example of the electric potential simulation of the image display medium which concerns on this invention. It is an example of the conceptual diagram of the image display apparatus which concerns on this invention. 2 is an individual electrode pattern of Example 1. FIG. 7 is an individual electrode pattern of Comparative Example 1.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

  First, an image display medium (electrophoretic display element) will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes an electrode (common electrode) made of a conductive layer, which is light transmissive. Here, as the common electrode 1, for example, a metal such as Al, Ag, Ni, or Cu or a transparent conductor such as ITO, SnO 2, or ZnO: Al is formed into a thin film by a sputtering method, a vacuum evaporation method, a CVD method, a coating method, or the like. For example, those formed into a shape, or those obtained by mixing a conductive agent with a solvent or a synthetic resin binder and applying the conductive agent are used.

  Examples of the conductive agent include cationic polymer electrolytes such as polymethylbenzyltrimethyl chloride and polyallylpolymethylammonium chloride, anionic polymer electrolytes such as polystyrene sulfonate and polyacrylate, and electron conductive materials. Zinc oxide, tin oxide, indium oxide fine powder or the like is used. In addition, the conductive layer may be thick enough to have a self-supporting function, or the conductive layer may be provided on a substrate having a self-supporting function (not shown). it can.

  In FIG. 1, reference numerals 2 and 3 denote individual electrodes made of a conductive layer. Since an electric field can be generated between the electrodes 1, 2, and 3, white or colored particles can be reliably moved. Further, in order to perform display, a voltage applying means (not shown) capable of applying a voltage to the electrode is prepared.

  In FIG. 1, 4 indicates a cell containing an electrophoretic particle dispersion. It is preferable to divide the two electrode substrates into a large number of fine cells because it is possible to prevent particle deviation and particle aggregation due to gravity.

  In FIG. 1, 5, 6, and 7 inside the cell are colored or white electrophoretic particles, and the colors and charging properties of 5, 6, and 7 are different from each other.

  As an example of the white electrophoretic particles constituting the particle dispersion, for example, solid particles of metal oxide such as silicon dioxide, aluminum oxide, and titanium oxide can be used. As an example of the colored electrophoretic particles, as the black colored particles, for example, carbon black, aniline black, furnace black, lamp black and the like can be used. Examples of cyan colored particles that can be used include phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, and ultramarine blue. As magenta colored particles, for example, rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake and the like can be used. As yellow colored particles, for example, chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, tartrazine and the like can be used.

  Further, the surface of the white or colored particles is preferably provided with a graft chain of a polymer component that is compatible with the dispersion medium in order to improve dispersion stability in the dispersion medium. In order to form the polymer component on the particle surface, a functional group contributing to the polymerization reaction may be added to the surface of the white or colored particle, and a known method may be used.

  Further, in the case of particles having a metal oxide surface such as titanium oxide, it is preferable to treat with a coupling agent having a functional group contributing to the polymerization reaction. For example, when vinyl groups are added to the surface. What is necessary is just to make it react with the silane coupling agent which has vinyl groups, such as 3- (trimethoxysilyl) propyl methacrylate. When the particles are carbon black, for example, a vinyl group can be imparted to the surface of carbon black by reacting with vinyl aniline. Electrophoretic particles in which a polymer component is grafted are obtained by graft polymerization reaction of particles and functional groups that contribute to the polymerization reaction. Alternatively, a monomer can be added in a state where white or colored particles are dispersed in a nonpolar solvent, and a polymer layer having a portion having a high affinity for the dispersion medium can be formed on the surface of white or colored particles simultaneously with polymerization. (Reference: JP 2005-265938 A).

  In FIG. 1, 8 is a dispersion medium. The dispersion medium 8 is preferably colorless and transparent so as not to adversely affect the contrast of the image based on the difference in color between the white or colored electrophoretic particles 5, 6 and 7. In particular, a nonpolar organic solvent having high electrical insulation is preferable. Examples of such nonpolar organic solvents include paraffinic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane and dodecane, isoparaffinic hydrocarbons such as isohexane, isooctane and isododecane, and alkyl naphthenes such as liquid paraffin. Hydrocarbons, aromatic hydrocarbons such as benzene, toluene, xylene, alkylbenzene, solvent naphtha, dimethyl silicone oil, phenylmethyl silicone oil, dialkyl silicone oil, alkylphenyl silicone oil, cyclic polydialkylsiloxane or cyclic polyalkylphenylsiloxane And silicone oil. In addition, a dispersant or the like may be further added to the dispersion medium 8 as necessary in order to control the dispersibility of the dispersed particles.

  The mass ratio of the electrophoretic particles in the electrophoretic particle dispersion is appropriately set so as to obtain a desired concentration of color, but about 1 to 50 mass% is appropriate. These components are added to a nonpolar solvent and mixed and dispersed to obtain a particle dispersion. In this case, known dispersing means such as a homogenizer, a ball mill, a sand mill, and an attritor may be used as the dispersing means.

  In the present embodiment, a desired voltage is applied to at least the individual electrodes 2 and 3 by voltage application means. In addition, the common electrode 1 may be applied with a voltage by a voltage applying means as with the individual electrodes 2 and 3, or may be grounded. In any case, the electrophoretic particles move according to their charge polarity and charge amount due to the electric field generated by the potential difference between the common electrode 1 and the individual electrodes 2 and 3.

  Next, a display method of the electrophoretic display element will be described with reference to FIGS.

  The example shown in FIGS. 2 to 4 is a case where the charge of the first particle 5 is zero, the charge of the second particle 6 is positive, and the charge of the third particle 7 is negative. As shown in FIG. 2, when a positive voltage is applied to the second electrode 2 and the third electrode 3 with respect to the first electrode 1, the second particles 6 positively charged on the first electrode 1 side. However, the negatively charged third particles 7 are attached to the second electrode 2 and the third electrode 3, and the second electrode 2 is observed from the outside (the upper portion in the drawing) of the first electrode 1, which is the observation point. The color of the particles 6 is observed.

  As shown in FIG. 3, when a negative voltage is applied to the second electrode 2 and the third electrode 3 with respect to the first electrode 1, the third particles 7, the second and second electrodes are applied to the first electrode 1. The second particle 6 adheres to the third electrode, and the color of the third particle 7 is observed from the observation point.

  As shown in FIG. 4, when a positive voltage is applied to the second electrode 2 and a negative voltage is applied to the third electrode 3, the third particles 7 adhere to the second electrode 2 and the third electrode 3. From the observation point, the first particles 5 dispersed and suspended in the electrophoresis solution are observed.

  According to the electrophoretic display element having such a configuration, three colors can be displayed in one cell. For example, when the first particles are white, the second particles are black, and the third particles are magenta, black and white and magenta can be displayed. If yellow and cyan are used instead of magenta, one of the three basic colors and three colors of black and white (in this specification, white and black are also considered as colors) will be considered as one electric. It can be displayed with an electrophoretic display element.

  Utilizing this principle, an electrophoretic display device (image display medium) using three electrophoretic display elements enables full color display. As shown in FIG. 5, each of the three electrophoretic display elements (first to third electrophoretic display elements 11, 12, and 13) has white particles 21 and black particles 22, each of which is yellow as a third particle. It has particles 23, magenta particles 24, and cyan particles 25.

  Each electrophoretic display element 11, 12, 13 shares the first electrode 14 and is controlled by the second and third electrodes 15, 16, 17, 18, 19, 20 with respect to the first electrode 14. Has been. The applied voltage in each electrophoretic display element may be controlled as described above, and white, black, and color (one of yellow, magenta, and cyan) can be displayed independently. In FIG. 5, the white particles are shown as substantially uncharged particles, but the present invention is not limited to this.

  According to such a display method, since each display element can display three colors, unlike the conventional color display device, four colors are added by adding black in addition to the three colors of yellow, magenta, and cyan. This display element is not required. Since all the electrophoretic display elements can display white and black, a clear color display with no unevenness can be achieved.

  Next, an image display medium and a driving method thereof according to the present invention will be described with reference to FIGS.

  The display method of each color in the image display medium is shown below. In this embodiment, when observing the color of the first particles, a positive voltage is applied to one electrode and a negative voltage is applied to the other electrode for the second electrode and the third electrode.

  When a plurality of cells in such a state are arranged, as in the prior art, the second electrode and the third electrode of each cell are shown in FIG. 6 (in this case, a display element for three-color display). In this way, an electric field due to a potential difference is generated between the second and third electrodes between adjacent cells (between 3A and 2B, 3B and 2C, etc.) via the partition walls 9 of the cells. FIG. 7 shows an example in which the potential in the cell at this time is simulated and equipotential lines are shown.

  As shown in FIG. 7, at the left and right ends of the cell, the particles move toward the adjacent cells, and a region where the particles stay is generated. In such a state, not only the first particles but also the colors of the second particles and the third particles are slightly observed, and the colors of the first particles cannot be displayed well. For example, if the first particles are white, the white reflectance will decrease.

  Therefore, in the image display medium according to the present invention, voltage application means applies the adjacent second or third individual electrodes through the cell partition walls 9 so as to have the same potential. That is, in the example of FIG. 8, the arrangement of the second electrode and the third electrode is exchanged for each adjacent cell. In this image display medium, there is no potential difference due to electrodes (such as between 3D and 3E, 2E and 2F) between adjacent cells via the partition walls 9 of the cells. FIG. 9 shows an example in which the potential in the cell at this time is simulated and equipotential lines are shown.

  Unlike the prior art, there is no region where the migrating particles stay at the left and right ends of the cell, and the particles can move between the second electrode and the third electrode in the single cell. Therefore, the display switching speed can be increased, and the color of the first particles can be observed well. For example, when the first particles are white, a high white reflectance can be obtained.

  Next, a method for producing an image display medium according to the present invention will be described. First, a second electrode and a third electrode are formed on a substrate. At this time, it is inverted for each adjacent cell so that the second electrode and the third electrode are on the same side between the adjacent cells.

  Next, cells filled with the electrophoretic liquid are formed on the second and third electrodes by photolithography or the like. In order to form the cell, an opening may be formed by applying a photoresist resin to the surface of the substrate on which the electrode is disposed and then removing the resin at the electrode portion to be paired. The width of the photoresist resin between the openings serving as the cell wall thickness is 0.5 to 20 μm, the thickness of the photoresist resin serving as the cell depth is 30 to 200 μm, and the pitch between the cells is formed within the range of 30 to 200 μm. To do.

  The electrophoresis solution is injected into the cell and sealed with a resin that is incompatible with the electrophoresis solution. In this case, examples of resins that are incompatible with the electrophoresis solution include polyurethane, polyurea, polyurea-polyurethane, urea-formaldehyde resin, melamine-formaldehyde resin, polyamide, polyester, polysulfonamide, polycarbonate, polysulfinate, epoxy resin. Acrylic acid ester, methacrylic acid ester, vinyl acetate, gelatin and the like. These resins are applied onto the electrophoretic solution by a coating device such as a slit coater and dried to form a film. In some cases, a surfactant is added to the resin to facilitate the formation of a film on the electrophoretic display liquid.

  Next, the sealed resin film and a glass substrate or a film such as PET on which the first electrode is formed are bonded to complete the electrophoretic display element.

  At this time, as a method of injecting different electrophoretic liquids into adjacent cells, there is a method of injecting different liquids into adjacent cells using an inkjet nozzle. By disposing different electrophoretic display liquids in adjacent cells, an electrophoretic display element for multicolor display is obtained.

  Next, an image display apparatus according to the present invention will be described with reference to FIG. As shown in FIG. 10, the image display device 30 includes the image display medium 10 according to the present invention described above. Further, the image display device 30 includes an information input means 31, a drive circuit (not shown), an arithmetic circuit, an internal memory, a power supply means, and the like. The electrodes in the display medium form a dot matrix, display the desired color by controlling the voltages of the two individual electrodes of the designated dot, and display the image as a whole. In addition, in FIG. 10, 32 is a housing. The power supply means may be provided with internal power such as a battery or a power receiving device such as an outlet receiving power from an external power source.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

Examples of the present invention will be described below. However, the present invention is not limited to the following examples. In addition, in description of an Example and a comparative example, unless there is particular notice, a part,%, etc. are a mass reference | standard.
<Example 1>
[Electrophoretic solution of white, black and magenta particles]
Polyvinyl naphthalene is used as white particles, carbon black is used as black particles, and quinacridone particles are used as magenta particles. Polyvinyl naphthalene was obtained by subjecting 2-vinylnaphthalene to Isopar G (trade name: manufactured by ExxonMobil, isoparaffin-based hydrocarbon), using silicon macromonomer as a dispersant, and performing dispersion polymerization to produce fine particles. Polyvinyl naphthalene shows good dispersion stability in Isopar G. Further, it was confirmed that the ζ potential indicating the charging of the particles was near zero, and the particles did not move by the electric field.

  Surface modification is performed to make carbon black negatively charged. The amino group is modified on the surface of the carbon black by silane coupling, and further hetero-aggregates with polymer fine particles polymerized with a pigment dispersant having a carboxyl group, methyl methacrylate and methacrylic acid, and adsorbs on the surface of the carbon black to improve the surface. Do the quality. Since carbon black is coated with carboxyl group-containing polymer fine particles, the charging characteristic is a negative property of the carboxyl group. It was confirmed that the zeta potential was negative and moved by the electric field.

  Surface modification is carried out to make quinacridone particles positively charged. As the quinacridone particles, PR-122 manufactured by Dainichi Seika was used. 2-Vinylaniline is diazo-coupled to the surface of the quinacridone particles, and 2-ethylhexyl methacrylate is graft-polymerized onto the surface of the quinacridone particles. The graft chain is subjected to charge control with a surfactant. Grain-polymerized quinacridone particles are dispersed in Isopar G, and Solsperse 17000 (trade name: manufactured by Avicia) is added as a surfactant. In this solvent, the ζ potential of the quinacridone particles was positive, and it was confirmed that the quinacridone particles were moved by the electric field. The above particles were blended at a blending ratio shown in Table 2 to prepare an electrophoresis solution.

[Electrophoretic display device with multi-color display]
As shown in FIG. 11 (not showing exact dimensions) on a 1 mm thick glass, second and third electrodes are formed in a comb-like shape every two lines by mask deposition of aluminum with a line of 30 μm and a distance of 20 μm. (Effective area 1 cm ² ). A square cell having a pitch of 100 μm is further formed thereon with a photoresist. SU-8 (manufactured by Nippon Kayaku Micro Corporation) is used as the photoresist. The thickness of the cell partition wall is 10 to 15 μm, the height of the cell partition wall is 40 to 50 μm, and the second and third electrodes are formed so as to be positioned one by one in the cell. The electrophoresis solution is injected into the formed cell. After removing the excess electrophoresis solution, a sealing film is formed on the solution to prevent the electrophoresis solution from drying. The sealing film used was a gelatin resin that was incompatible with the electrophoresis solution, and a polyoxyethylene surfactant was added to reduce the surface tension with the electrophoresis solution. In the state which heated the gelatin resin aqueous solution to about 40 degreeC, it apply | coats on an electrophoresis liquid using a slit coater, and gelatin is dried and a sealing film is formed. Next, an electrophoretic display element with three colors is obtained by applying an adhesive on the sealing film and adhering a PET film on which ITO is formed.

[Display operation]
When -15V was applied to the second and third electrodes, magenta was displayed. When + 15V was applied, black was displayed. When + 10V was applied to the second electrode and -10V was applied to the third electrode, white was displayed. The white reflectance at this time was 45%.

<Comparative Example 1>
As shown in FIG. 12, a cell was produced and a display operation was performed in the same manner as in Example 1 except that the second electrode and the third electrode were alternately arranged one by one without being inverted. The white reflectance at the time of white display at this time was 30%.

  From the above, it was confirmed that the image display medium according to the present invention can obtain a high white reflectance.

1,14 Common electrode (first common electrode)
2,2A to 2F, 15,17,19 Individual electrode (second individual electrode)
3,3A-3F, 16,18,20 Individual electrode (third individual electrode)
4 cell 5 first electrophoretic particle (first particle)
6 Second electrophoretic particles (second particles)
7 Third electrophoretic particles (third particles)
8 Dispersion medium 9 Cell partition wall 10 Image display medium 11 First electrophoretic display element 12 Second electrophoretic display element 13 Third electrophoretic display element 21 White particles 22 Black particles 23 Yellow particles 24 Magenta particles 25 Cyan particles 30 Image display device 31 Information input means 32 Case

JP-A-5-173194 Japanese Patent Laid-Open No. 1-300231 Special Table 2002-511607 JP 2009-9092 A

Claims (3)

A fine particle dispersion composed of at least a nonpolar solvent and particles is enclosed between two electrode substrates in a plurality of partitioned cells, and the electrode substrate includes a light-transmitting first common electrode and a partition The fine particle dispersion liquid is an electrophoretic liquid in which three kinds of dispersible particles are dispersed, and includes two second and third individual electrodes provided for one formed cell. The first dispersible particles are substantially free of charge, the second dispersible particles are electrophoretic particles having a positive charge, and the third dispersible particles are electrophoretic liquids having a negative charge. Yes,
The dispersible particles by applying a voltage between the first common electrode and the second and third individual electrodes and / or between the second and third individual electrodes corresponding to one cell. A display layer that performs a display operation by electrophoresis of
In an image display medium comprising at least a voltage applying means for applying a desired voltage between the second and third individual electrodes,
The image display medium according to claim 1, wherein the voltage applying means applies the individual electrodes adjacent to each other through the partition walls of the cell so as to have the same potential.   The image display medium according to claim 1, comprising: information input means for supplying image information to the image display medium; and power supply means for supplying power to the image display medium and the information input means. An image display device. A fine particle dispersion composed of at least a nonpolar solvent and particles is enclosed between two electrode substrates in a plurality of partitioned cells, and the electrode substrate includes a light-transmitting first common electrode and a partition The fine particle dispersion liquid is an electrophoretic liquid in which three kinds of dispersible particles are dispersed, and includes two second and third individual electrodes provided for one formed cell. The first dispersible particles are substantially free of charge, the second dispersible particles are electrophoretic particles having a positive charge, and the third dispersible particles are electrophoretic liquids having a negative charge. Yes,
The dispersible particles by applying a voltage between the first common electrode and the second and third individual electrodes and / or between the second and third individual electrodes corresponding to one cell. A display layer that performs a display operation by electrophoresis of
In a driving method for switching display of an image display medium comprising at least a voltage applying means for applying a desired voltage between the second and third individual electrodes,
The method for driving an image display medium, wherein the voltage application means applies the individual electrodes adjacent to each other through the partition walls of the cell so as to have the same potential.

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