JP2010020004A - Electrophoretic display sheet, electrophoretic display device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display sheet and an electrophoretic display device having high display contrast and excellent visibility, and also to provide electronic equipment having high reliability provided with the above electrophoretic display device. <P>SOLUTION: The electrophoretic display device 1 has: first electrophoretic particles (A) charged into positive or negative; second electrophoretic particles (B) charged into the opposite polarity to the first electrophoretic particles (A) and giving a color with lower lightness than the first electrophoretic particles (A); a common space S1 where the first electrophoretic particles (A) and the second electrophoretic particles (B) can perform electrophoresis each other; a housing space S2 communicating with the common space S1 and housing the second electrophoretic particles (B); a light reflecting face 711 having metallic gloss, disposed adjacent to the housing space S2; and a pair of electrodes 61, 62 disposed opposing to each other across the common space S1 and the housing space S2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophoretic display sheet, an electrophoretic display device, and an electronic apparatus.

For example, an electrophoretic display using particle electrophoresis is known as an image display unit of electronic paper (see, for example, Patent Document 1). The electrophoretic display has excellent portability and power saving, and is particularly suitable as an image display unit of electronic paper.
Patent Document 1 describes a display device including individual transparent electrodes and a common electrode arranged to face each other and cells provided therebetween. The cell is composed of a separation member and a sealing member. Such a cell has a conical shape with a smaller cross-sectional area from the individual transparent electrode side toward the common electrode side. The cell is filled with an insulating liquid in which charged colored particles are dispersed.

  In the display device of Patent Document 1, when charged colored particles gather on the individual transparent electrode side, the color of the charged colored particles is visually recognized through the individual transparent electrode (that is, the color of the charged colored particles is displayed as the display color). When the charged particles are collected on the common electrode side, the color of the separating member (the color of the inner wall of the cell) other than where the charged colored particles are collected is dominantly visually recognized. The color switching is performed by causing the charged colored particles to undergo electrophoresis by generating a predetermined electric field between the individual transparent electrode and the common electrode.

  In such a display device, for example, black and white display is possible if the charged colored particles are black and the separating member is white. However, in the case of white display, an aggregate (black portion) formed by locally gathering charged colored particles locally on the common electrode side (that is, near the apex of the conical cell) is an individual transparent electrode. Therefore, a bright white display cannot be performed. Therefore, it is difficult for the display device of Patent Document 1 to perform high contrast display.

Japanese Patent Publication No. 6-52358

  An object of the present invention is to provide an electrophoretic display sheet, an electrophoretic display device having high display contrast and excellent visibility, and a highly reliable electronic device including the electrophoretic display device.

Such an object is achieved by the present invention described below.
The electrophoretic display sheet of the present invention includes positively or negatively charged first electrophoretic particles,
A second electrophoretic particle that is charged to the opposite polarity to the first electrophoretic particle and has a lighter color than the first electrophoretic particle;
A shared space in which the first electrophoretic particles and the second electrophoretic particles can migrate to each other;
A storage space that communicates with the shared space and stores the second electrophoretic particles;
A light reflecting surface having a metallic luster provided adjacent to the accommodation space;
It has a pair of electrodes opposingly arranged through the said common space and the said accommodation space, It is characterized by the above-mentioned.
Thereby, an electrophoretic display sheet having high display contrast and excellent visibility can be provided. In addition, the electrophoretic display sheet can be reduced in thickness and power can be saved.

In the electrophoretic display sheet of the present invention, the electrophoretic display sheet has a laying portion having a surface facing the housing space and a groove opened to the surface, the surface of the laying portion forms the light reflecting surface, and the groove It is preferable to constitute the accommodation space.
Thereby, formation of a light reflection surface and accommodation space becomes comparatively easy.
In the electrophoretic display sheet of the present invention, it is preferable that the light reflection surface is provided so as to be orthogonal to the migration direction of the first electrophoretic particles and the second electrophoretic particles.
Thereby, since the external light incident in the shared space can be efficiently reflected by the light reflecting surface, the brightness and display contrast of white display can be increased.

In the electrophoretic display sheet of the present invention, it is preferable that the depth direction of the groove is parallel to the electrophoretic direction of the first electrophoretic particles and the second electrophoretic particles.
Accordingly, the second electrophoretic particles can easily enter the groove (accommodating space), and the second electrophoretic particles can be accommodated in the groove more reliably. Therefore, the brightness and display contrast of white display can be increased.

In the electrophoretic display sheet of the present invention, it is preferable that the depth direction of the groove is inclined with respect to the migration direction of the first electrophoretic particles and the second electrophoretic particles.
Thereby, the inside (accommodation space) of the groove is less likely to be visually recognized. For this reason, the second electrophoretic particles housed in the groove are also less noticeable. As a result, the brightness and display contrast of white display can be further increased.

In the electrophoretic display sheet of the present invention, the depth of the groove is preferably larger than the outer diameter of the second particle.
As a result, there is no second electrophoretic particle that cannot be physically accommodated in the groove, and as a result, the brightness and display contrast of white display can be increased.
In the electrophoretic display sheet of the present invention, the width of the groove is preferably larger than the outer diameter of the second electrophoretic particle and smaller than the outer diameter of the first electrophoretic particle.
Thereby, it is possible to prevent the first electrophoretic particles from being accommodated in the groove, and the first electrophoretic particles are fixed to the inner wall of the groove, thereby reducing the storage space and migrating. A reduction in the number of possible first electrophoretic particles is prevented. As a result, the display contrast can be increased and the display characteristics (initial characteristics) can be maintained for a long time.
In the electrophoretic display sheet of the present invention, the grooves are preferably formed in a lattice shape.
Thereby, the accommodating space can be formed sufficiently and uniformly to accommodate the second electrophoretic particles.

The electrophoretic display sheet of the present invention includes positively or negatively charged first electrophoretic particles,
A second electrophoretic particle that is charged to the opposite polarity to the first electrophoretic particle and has a lighter color than the first electrophoretic particle;
A shared space in which the first electrophoretic particles and the second electrophoretic particles can migrate to each other;
A storage space that communicates with the shared space and stores the second electrophoretic particles;
A surface provided adjacent to the housing space and having a lightness higher than the lightness of the color of the second electrophoretic particles;
It has a pair of electrodes opposingly arranged through the said common space and the said accommodation space, It is characterized by the above-mentioned.
Thereby, an electrophoretic display sheet having high display contrast and excellent visibility can be provided. In addition, the electrophoretic display sheet can be reduced in thickness and power can be saved.

In the electrophoretic display sheet of the present invention, the colored surface is preferably white.
This further increases the display contrast.
In the electrophoretic display sheet of the present invention, the electrophoretic display sheet has a laying portion having a surface facing the accommodation space and a groove opened to the surface, and the surface of the laying portion has a lightness of the color of the second electrophoretic particle. It is preferable that the surface which has higher brightness is comprised, and the said groove | channel comprises the said accommodation space.
Thereby, formation of a light reflection surface and accommodation space becomes comparatively easy.
In the electrophoretic display sheet of the present invention, it is preferable that the colored surface is provided so as to be orthogonal to the migration direction of the first electrophoretic particles and the second electrophoretic particles.
Thereby, since the external light incident in the shared space can be efficiently reflected by the light reflecting surface, the brightness and display contrast of white display can be increased.

In the electrophoretic display sheet of the present invention, it is preferable that the depth direction of the groove is parallel to the electrophoretic direction of the first electrophoretic particles and the second electrophoretic particles.
Accordingly, the second electrophoretic particles can easily enter the groove (accommodating space), and the second electrophoretic particles can be accommodated in the groove more reliably. Therefore, the brightness and display contrast of white display can be increased.

In the electrophoretic display sheet of the present invention, it is preferable that the depth direction of the groove is inclined with respect to the migration direction of the first electrophoretic particles and the second electrophoretic particles.
Thereby, the inside (accommodation space) of the groove is less likely to be visually recognized. For this reason, the second electrophoretic particles housed in the groove are also less noticeable. As a result, the brightness and display contrast of white display can be further increased.

In the electrophoretic display sheet of the present invention, the depth of the groove is preferably larger than the outer diameter of the second particle.
As a result, there is no second electrophoretic particle that cannot be physically accommodated in the groove, and as a result, the brightness and display contrast of white display can be increased.
In the electrophoretic display sheet of the present invention, the width of the groove is preferably larger than the outer diameter of the second electrophoretic particle and smaller than the outer diameter of the first electrophoretic particle.
Thereby, it is possible to prevent the first electrophoretic particles from being accommodated in the groove, and the first electrophoretic particles are fixed to the inner wall of the groove, thereby reducing the storage space and migrating. A reduction in the number of possible first electrophoretic particles is prevented. As a result, the display contrast can be increased and the display characteristics (initial characteristics) can be maintained for a long time.
In the electrophoretic display sheet of the present invention, the grooves are preferably formed in a lattice shape.
Thereby, the accommodating space can be formed sufficiently and uniformly to accommodate the second electrophoretic particles.

In the electrophoretic display sheet of the present invention, it is preferable that the storage portion is configured to store only the second electrophoretic particles.
Thereby, it is possible to prevent the first electrophoretic particles from being accommodated in the groove, and the first electrophoretic particles are fixed to the inner wall of the groove, thereby reducing the storage space and migrating. A reduction in the number of possible first electrophoretic particles is prevented. As a result, the display contrast can be increased and the display characteristics (initial characteristics) can be maintained for a long time.
In the electrophoretic display sheet of the present invention, it is preferable that the first electrophoretic particles are white particles, and the second electrophoretic particles are black particles.
As a result, monochrome display is possible and display contrast can be increased.

The electrophoretic display device of the present invention includes the electrophoretic display sheet of the present invention and a substrate provided on the accommodation space side of the electrophoretic display sheet.
Thereby, an electrophoretic display device with high display contrast and excellent visibility can be provided. In addition, the electrophoretic display sheet can be reduced in thickness and power can be saved.
In the electrophoretic display device of the present invention, the electrophoretic display device has a plurality of the accommodating spaces arranged in a planar shape, and the electric field is generated or generated for each one or two or more of the accommodating spaces. It is preferable that cancellation can be selected.
Thereby, it is possible to display an image made up of a large number of pixels.
An electronic apparatus according to the present invention includes the electrophoretic display device according to the present invention.
Thereby, an electronic apparatus including an electrophoretic display device with excellent visibility can be provided. In addition, the electrophoretic display sheet can be reduced in thickness and power can be saved.

Hereinafter, an electrophoretic display sheet, an electrophoretic display device, and an electronic apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<Electrophoretic display device>
<< First Embodiment >>
First, a first embodiment of an electrophoretic display device (electrophoretic display device of the present invention) to which the electrophoretic display sheet of the present invention is applied will be described.

  FIG. 1 is a longitudinal sectional view schematically showing a first embodiment of the electrophoretic display device of the present invention, FIG. 2 is an enlarged plan view showing a bottom part of the electrophoretic display device of FIG. 1, and FIG. FIG. 4 and FIG. 5 are cross-sectional views illustrating the operation of the electrophoretic display device shown in FIG. 1, and FIG. 6 and FIG. 6 is a cross-sectional view illustrating a method for manufacturing the electrophoretic display device shown in FIG. In the following description, the upper side in FIGS. 1 and 3 to 7 is referred to as “upper”, and the lower side is referred to as “lower”. As shown in FIG. 1, the three axes orthogonal to each other are defined as an x-axis, a y-axis, and a z-axis, respectively.

The electrophoretic display device 1 shown in FIG. 1 includes a circuit board (back plane) 8 and an electrophoretic display sheet 2 bonded to the upper surface of the circuit board 8. The circuit board 8 has a flat base 81 and a circuit (not shown) including a switching element such as a TFT provided on the base 81.
As shown in FIG. 1, the electrophoretic display sheet 2 includes a display layer 5, a common electrode 61 provided on the upper side of the display layer 5, and an individual electrode 62 provided on the lower side of the display layer 5. ing. The individual electrode 62 includes a plurality of electrode pieces 621 arranged in a matrix and spaced apart from each other. Each electrode piece 621 is connected to the switching element described above. Thereby, a voltage can be applied to each electrode piece 621 independently.

The display layer 5 includes a separation member 31 in which a plurality of recesses 7 recessed downward are formed in a matrix, and a sheet shape (plate shape) joined to the separation member 31 so as to close the upper opening of the recess 7. The sealing member 32 is provided.
The separation member 31 and the sealing member 32 are liquid-tightly joined. Therefore, the accommodating portion 4 is defined by the inner surface (inner wall) of each recess 7 and the lower surface of the sealing member 32. The accommodating portion 4 is formed so as to correspond to the plurality of electrode pieces 621 described above. Each container 4 is filled with an electrophoretic dispersion 10 in which two types of electrophoretic particles, that is, first electrophoretic particles A and second electrophoretic particles B are dispersed in a liquid phase dispersion medium. Yes. Each of such storage units 4 corresponds to each pixel constituting the display content.

Each recess 7 has a bottom portion (laying portion) 71. The bottom portion 71 has a light reflecting surface 711 facing the housing portion 4 and a groove 712 communicating with the housing portion 4 (opening to the light reflecting surface 711). Thus, when the bottom portion 71 has the groove 712, it can be said that the internal space of the accommodating portion 4 is configured by the internal space of the groove 712 and the other space (the space above the groove 712). As will be described later, the internal space of the groove 712 is an accommodation space S2 that accommodates the second electrophoretic particles B, and the other spaces contain the first electrophoretic particles A and the second electrophoretic particles B. This is a shared space S1 that migrates to each other.
In the electrophoretic display device 1 having such a configuration, a voltage is applied between the common electrode 61 and the individual electrode 62 to cause a desired electric field to act on each housing portion 4, and the electrophoretic particles A, By migrating B in the shared space S1, the color in each container 4 visually recognized through the common electrode 61 is changed, and desired image information and character information are displayed.

Below, the one accommodating part 4 is taken up and the structure of each part is demonstrated one by one. In addition, in the some accommodating part 4, the structure of the following each part is the same.
Of the separating member 31 and the sealing member 32, at least the sealing member 32 is substantially colorless and transparent. Thereby, the inside of the accommodating part 4 can be visually recognized through the sealing member 32 from the upper side in FIG. Note that the sealing member 32 may not be colorless and transparent as long as the inside of the accommodating portion 4 can be visually recognized via the sealing member 32 (that is, as long as the sealing member 32 has light transmittance). May be.

The separation member 31 and the sealing member 32 may be either flexible or hard, but preferably have flexibility. By using the flexible one, the electrophoretic display device 1 having the flexibility can be obtained. This is advantageous in constructing, for example, electronic paper.
Further, when the separation member 31 and the sealing member 32 are flexible, the constituent materials thereof include, for example, polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer, modified polyolefins, polyamides, respectively. (Example: nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66), thermoplastic polyimide, liquid crystal polymer such as aromatic polyester, polyphenylene oxide, Polyphenylene sulfide, polycarbonate, polymethyl methacrylate, polyether, polyether ether ketone, polyether imide, polyacetal, styrene, polyolefin, polyvinyl chloride, polyurethane, polyester , Polyamide-based, polybutadiene-based, trans-polyisoprene-based, fluoro-rubber-based, chlorinated polyethylene-based thermoplastic elastomers, etc., or copolymers, blends, polymer alloys, etc. mainly composed of these. One or two or more of them can be used in combination.

  The thickness of the separation member 31 and the thickness of the sealing member 32 are not particularly limited, but are designed such that the total thickness of each other (that is, the thickness of the display layer 5) is about 10 to 500 μm. It is preferable that the thickness is designed to be about 20 to 100 μm. Accordingly, the electrophoretic display device 1 can be reduced in size (particularly thinned) while achieving harmony between flexibility and strength of the electrophoretic display device 1.

  Of the common electrode 61 and the individual electrode 62, at least the common electrode 61 is substantially colorless and transparent. Thereby, the inside of the accommodating part 4 can be visually recognized through the common electrode 61 and the sealing member 32 from the upper side in FIG. The common electrode 61 does not have to be colorless and transparent as long as the inside of the accommodating portion 4 can be visually recognized through the common electrode 61 (that is, as long as the common electrode 61 has light transmittance). May be.

The constituent materials of the common electrode 61 and the individual electrode 62 are not particularly limited as long as they are substantially conductive. For example, copper, aluminum, nickel, cobalt, platinum, gold, silver, molybdenum, tantalum Or metal materials such as alloys containing these, carbon-based materials such as carbon black, carbon nanotubes, fullerene, polyacetylene, polypyrrole, polythiophene, polyaniline, poly (p-phenylene), poly (p-phenylenevinylene), polyfluorene, poly Various ionic substances are dispersed in a matrix resin such as an electronically conductive polymer material such as carbazole, polysilane or a derivative thereof, polyvinyl alcohol, polycarbonate, polyethylene oxide, polyvinyl butyral, polyvinyl carbazole, or vinyl acetate. Ionic conductive polymer material, indium tin oxide (ITO), such as fluorine doped tin oxide (FTO), tin oxide (SnO _2), indium oxide (IO) conductive oxides such materials Various conductive materials can be mentioned, and one or more of these can be used in combination.

In addition, as the constituent material of the common electrode 61 and the individual electrode 62, for example, conductive materials such as gold, silver, nickel, carbon, etc. in non-conductive materials such as glass materials, rubber materials, and polymer materials, respectively. Various composite materials in which conductive materials (conductive particles) are mixed to add conductivity can also be used.
Specific examples of such a composite material include, for example, a conductive rubber in which a conductive material is mixed in a rubber material, a conductive rubber in which an electrically conductive material is mixed in an adhesive composition such as epoxy, urethane, and acrylic. In matrix resins such as conductive adhesive or conductive paste, polyolefin, polyvinyl chloride, polystyrene, ABS resin, nylon (polyamide), ethylene vinyl acetate copolymer, polyester, acrylic resin, epoxy resin, urethane resin Examples thereof include a conductive resin mixed with a conductive material.
The average thicknesses of the common electrode 61 and the individual electrode 62 are appropriately set depending on the constituent materials and the like, and are not particularly limited, but are preferably about 0.05 to 10 μm, and about 0.05 to 5 μm. More preferably.

Next, the electrophoretic dispersion 10 filled in the storage unit 4 will be described.
The electrophoretic dispersion 10 is obtained by dispersing first electrophoretic particles A and second electrophoretic particles B in a liquid phase dispersion medium. The dispersion of the electrophoretic particles A and B in the liquid phase dispersion medium is, for example, a combination of one or more of paint shaker method, ball mill method, media mill method, ultrasonic dispersion method, stirring dispersion method and the like. It can be carried out.

As the liquid phase dispersion medium, a medium having a relatively high insulating property is preferably used.
Examples of the liquid phase dispersion medium include aromatics such as benzene hydrocarbons such as benzene, toluene, o-xylene, m-xylene, p-xylene, mixed xylene, ethylbenzene, hexylbenzene, dodecylbenzene, and phenylxylylethane. Group hydrocarbons: paraffinic hydrocarbons such as n-hexane and n-decane, isoparaffinic hydrocarbons such as Isopar (Isopar, manufactured by Exxon Chemical), olefinic hydrocarbons such as 1-octene and 1-decene, cyclohexane , Aliphatic hydrocarbons such as naphthenic hydrocarbons such as decalin; petroleum and petroleum-derived hydrocarbon mixtures such as kerosene, petroleum ether, petroleum benzine, ligroin, industrial gasoline, coal tar naphtha, petroleum naphtha and solvent naphtha; dichloromethane , Chloroform, four Carbon, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, trichlorofluoroethane, tetrabromoethane, dibromotetrafluoroethane, tetrafluorodiiodoethane, 1,2 -Halogenated hydrocarbons such as dichloroethylene, trichloroethylene, tetrachloroethylene, trichlorofluoroethylene, chlorobutane, chlorocyclohexane, chlorobenzene, o-dichlorobenzene, bromobenzene, iodomethane, diiodomethane, iodoform; silicones such as dimethyl silicone oil and methylphenyl silicone oil At least selected from the group consisting of oils (organic silicone oils); fluorinated solvents such as hydrofluoroethers (organic fluorinated solvents); One is preferably used.
Among the organic solvents described above, long-chain alkylbenzenes such as hexylbenzene and dodecylbenzene, phenylxylylethane, and the like are particularly preferably used because of their high boiling point and flash point and little toxicity.

  In addition to the above-mentioned liquid phase dispersion medium, for example, cellosolves such as methyl cellosolve, ethyl cellosolve, phenyl cellosolve, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl formate, acetone, methyl ethyl ketone, diethyl Ketones, ketones such as methyl isobutyl ketone, methyl isopropyl ketone and cyclohexanone, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, aromatic heterocycles such as pyridine, pyrazine, furan, pyrrole, thiophene and methylpyrrolidone Nitriles such as acetonitrile, propionitrile and acrylonitrile, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, carboxylates and the like can be used.

In the liquid phase dispersion medium, for example, a surfactant (anionic or cationic) such as an electrolyte or an alkenyl succinate, a metal soap, a resin material, a rubber material, an oil, a varnish may be used as necessary. Various additives such as a charge control agent composed of particles such as a compound, a dispersant such as a silane coupling agent, a lubricant, and a stabilizer may be added.
Furthermore, when coloring a liquid phase dispersion medium, you may make it melt | dissolve various dyes, such as an anthraquinone dye, an azo dye, an indigoid dye, in a liquid phase dispersion medium as needed.

  The first electrophoretic particles A and the second electrophoretic particles B are charged with opposite polarities. Therefore, when an electric field acts on these electrophoretic particles A and B (when a voltage is applied between the common electrode 61 and the individual electrode 62), the first electrophoretic particles A and the second electrophoretic particles B are: Electrophoresis in liquid phase dispersion medium in opposite directions. Below, for convenience of explanation, the case where the first electrophoretic particles A are positively charged particles and the second electrophoretic particles B are negatively charged particles will be described as a representative. Note that this may be reversed.

Further, the first electrophoretic particles A and the second electrophoretic particles B have different colors. The colors of the first electrophoretic particles A and the second electrophoretic particles B are not particularly limited as long as they are different from each other. For example, achromatic colors such as white, black, or an intermediate color (gray) thereof can be used. , Chromatic colors such as red, blue and green.
The combination of the colors of the first electrophoretic particles A and the second electrophoretic particles B is not particularly limited. For example, the first electrophoretic particles A are white particles, and the second electrophoretic particles B are black. And combinations in which the first electrophoretic particles A are blue particles, and the second electrophoretic particles B are red particles. Among these, as a combination of the colors of the first electrophoretic particles A and the second electrophoretic particles B, a combination of white and black is particularly preferable. Thereby, in the electrophoretic display device 1, monochrome display is possible and display contrast can be increased. Hereinafter, for convenience of explanation, the case where the first electrophoretic particles A are white particles and the second electrophoretic particles B are black particles will be described. Note that this may be reversed. Hereinafter, for convenience of explanation, the first electrophoretic particles A are also referred to as “white particles A”, and the second electrophoretic particles B are also referred to as “black particles B”.

Any white particles A and black particles B can be used as long as they have an electric charge. Although not particularly limited, pigment particles, resin particles, or composite particles thereof can be used. At least one is preferably used. These particles have the advantage that they can be easily manufactured and the amount of charge can be controlled relatively easily.
Examples of pigments constituting the pigment particles include black pigments such as aniline black, carbon black, and titanium black, white pigments such as titanium oxide and antimony oxide, azo pigments such as monoazo, yellow such as isoindolinone and yellow lead. Pigments, red pigments such as quinacridone red and chrome vermilion, blue pigments such as phthalocyanine blue and indanthrene blue, green pigments such as phthalocyanine green, and the like. Of these, one or a combination of two or more may be used. it can.
Among these, as pigment particles, titanium oxide particles are suitably used as white particles A, and titanium black particles are suitably used as black particles B. These particles have high responsiveness to an electric field and a large difference in reflectance, so that high contrast display is possible.

Examples of the resin material constituting the resin particles include acrylic resin, urethane resin, urea resin, epoxy resin, polystyrene, polyester, and the like, and one or more of these are combined. Can be used.
The composite particles include, for example, those in which the surface of the pigment particles is coated with a resin material or other pigment, those in which the surface of the resin particles is coated with a pigment, or a mixture in which the pigment and the resin material are mixed at an appropriate composition ratio. The particle | grains comprised by these, etc. are mentioned.
Examples of particles obtained by coating the surface of pigment particles with other pigments include those obtained by coating the surface of titanium oxide particles with silicon oxide or aluminum oxide.
The shapes of the white particles A and the black particles B are not particularly limited, but are preferably spherical.

  When the dispersibility in the liquid phase dispersion medium is taken into consideration for each of the white particles A and the black particles B, smaller ones are preferably used. Specifically, the average particle diameter is about 10 to 500 nm. It is preferable that it is about 20 to 300 nm. By setting the average particle diameters of the white particles A and the black particles B within the above ranges, the aggregation and settling of the white particles A and the black particles B can be reliably prevented, and the white particles A and the black particles B can be used as a liquid phase dispersion medium. Can be dispersed in. As a result, display quality deterioration of the electrophoretic display device 1 can be suitably prevented.

In the present embodiment, it is preferable to set the average particle size of the white particles A to be larger than the average particle size of the black particles B. As a result, only the black particles B are accommodated in the groove 712 formed in the bottom 71 of the recess 7. As a result, as described later, the electrophoretic display device 1 can increase the brightness and display contrast of white display of the electrophoretic display device 1 and can maintain the initial characteristics for a long time.
More specifically, when the average particle diameter of the white particles A is D1 and the average particle diameter of the black particles B is D2, it is preferable that D1 is about 1.5D2 to 15D2. Furthermore, the average particle size of the black particles B is preferably about 20 to 100 nm, and the average particle size of the white particles A is preferably about 150 to 300 nm.

The specific gravity of the white particles A and the black particles B is preferably set so as to be approximately equal to the specific gravity of the liquid phase dispersion medium. Thereby, even after the application of the voltage between the common electrode 61 and the individual electrode 62 is stopped, the white particles A and the black particles B can stay in a certain position in the liquid phase dispersion medium for a long time.
That is, such an electrophoretic display device 1 has a property (bistability) that can maintain a display state when a voltage is applied between the common electrode 61 and the individual electrode 62 even after the application of the voltage is stopped. Is.

  In the electrophoretic display device 1 having such a property (bistability), it is only necessary to apply a voltage between the common electrode 61 and the individual electrode 62 only at the time of switching the display, so that power consumption can be greatly reduced. Become. In addition, since the white particles A and the black particles B migrate stably, the voltage can be applied in various patterns such as applying a voltage in small increments, and the electrophoresis of the electrophoretic particles can be controlled more complicatedly. It becomes possible. For this reason, display quality can be improved.

Subsequently, the bottom part (laying part) 71 which the recessed part 7 has is demonstrated.
FIG. 2 is an enlarged plan view of the bottom 71, and FIG. 3 is a cross-sectional view of the bottom 71. 2 and 3, illustration of the electrophoretic dispersion liquid 10 is omitted for convenience of explanation.
FIG. 2 is a plan view of the bottom 71 when viewed from the common electrode 61 side. As shown in the figure, the bottom 71 has a light reflecting surface 711 facing the shared space S1, and a groove 712 communicating with the shared space S1 (opening to the light reflecting surface 711).

The groove 712 is a housing space S2 that houses the black particles B.
As shown in FIG. 2, the groove 712 includes a plurality of x-axis direction extending grooves 712x formed along the x-axis direction, and a plurality of y-axis direction extending grooves 712y formed along the y-axis direction. It consists of The plurality of x-axis direction extending grooves 712x are formed at an equal pitch, and similarly, the plurality of y-axis direction extending grooves 712y are also formed at an equal pitch. The pitch of the x-axis direction extending grooves 712x is equal to the pitch of the y-axis direction extending grooves 712y.
That is, in this embodiment, it can be said that the grooves 712 are formed in a lattice shape. By thus forming the grooves 712 in a lattice shape, it is possible to easily and uniformly form the accommodation space S2 having a size sufficient to accommodate the black particles B.

Hereinafter, the x-axis direction extending groove 712x and the y-axis direction extending groove 712y will be described. The x-axis direction extending groove 712x and the y-axis direction extending groove 712y have the same configuration (width, depth, etc.). Shape), the x-axis direction extending groove 712x will be described as a representative, and the y-axis direction extending groove 712y will not be described.
The width (length indicated by W in FIG. 2) and the depth (length indicated by T in FIG. 3) of each x-axis direction extending groove 712x are each larger than the maximum particle diameter of the black particles B. Is preferred. Thereby, all the black particles B can be accommodated in the x-axis direction extending groove 712x. In other words, there is no black particle B that cannot physically enter the x-axis direction extending groove 712x. Therefore, as will be described later, the brightness and display contrast of white display can be increased.

  The width of each x-axis direction extending groove 712x is preferably smaller than the minimum particle diameter of the white particles A. Thereby, the white particles A cannot enter the x-axis direction extending groove 712x. Therefore, as will be described later, it is possible to obtain the electrophoretic display device 1 that can maintain the initial characteristics (the brightness and contrast of the initial white display) even when the display color is repeatedly switched.

  The width W of each x-axis direction extending groove 712x is not particularly limited, but is preferably about 1.1 to 2.0 times the maximum outer diameter D2max of the black particles B, preferably 1.3 to 1.5 times. More preferred is the degree. Moreover, the width W of each x-axis direction extending groove 712x is not particularly limited, but is preferably about 0.9 to 0.1 times the minimum outer diameter D1min of the white particles A, preferably 0.1 to 0. 0. More preferably, it is about 5 times. By making the width W of each x-axis direction extending groove 712x within the above range, the above effect becomes more remarkable. That is, the brightness and display contrast of white display can be increased, and the display characteristics (initial characteristics) can be maintained for a long time.

  Further, as shown in FIG. 3, each x-axis direction extending groove 712x is formed such that its depth direction is parallel to the z-axis direction. As a result, the black particles B easily enter the x-axis direction extending grooves 712x, and the black particles B can be more reliably accommodated in the x-axis direction extending grooves 712x. Therefore, the brightness and display contrast of white display can be increased.

The light reflecting surface 711 has a metallic luster. Thus, when the light reflecting surface 711 has a metallic luster, it is possible to efficiently reflect the external light that has entered the housing portion 4 from the common electrode 61 side. Thereby, as will be described later, the brightness and display contrast of white display can be increased.
The light reflecting surface 711 is formed to be substantially parallel to the xy plane defined by the x axis and the y axis. As will be described later, when the electrophoretic display device 1 is operated, the white particles A and the black particles B migrate in the z-axis direction, so that the light reflecting surface 711 is opposed to the migration direction of the white particles A and the black particles B. It can also be said that they are provided so as to be orthogonal. As a result, the light reflecting surface 711 faces the upper opening (common electrode 61) of the concave portion 7, and the external light incident on the accommodating portion 4 from the common electrode 61 side can be reflected more efficiently. Therefore, the brightness and display contrast of white display can be increased.

The light reflecting surface 711 includes a plurality of unit light reflecting surfaces 711a. That is, each unit light reflection surface 711a is formed so as to be substantially parallel to the xy plane and has a metallic luster. Each unit light reflecting surface 711a is defined by a pair of adjacent x-axis direction extending grooves 712x and a pair of adjacent y-axis direction extending grooves 712y.
For example, the light reflecting surface 711 is formed on the upper surface of the bottom 71 by a metal material such as aluminum, silver, nickel, chromium, tin, tantalum, palladium, platinum, iridium, hafnium, molybdenum, or one or two of these metal materials. It can be obtained by forming a thin film composed mainly of an alloy (or mixture) containing more than one species. Among these, the light reflecting surface 711 is more preferably a thin film composed mainly of aluminum or silver. Since these materials have an excellent metallic luster, a light reflecting surface 711 having a high light reflectance can be obtained.
As described above, providing the light reflecting surface 711 and the groove 712 (accommodating space S2) in the bottom 71 makes it relatively easy to form them.

-Operation of the electrophoretic display device 1-
Such an electrophoretic display device 1 operates as follows. In the following description, the upper side in FIGS. 4 and 5 is referred to as “upper” and the lower side is referred to as “lower”. In the following, for convenience of explanation, the case where the white particles A are positively charged and the black particles B are negatively charged will be described as a representative.

≪White display state≫
First, a state where white (the color of the white particles A) is visually recognized as a display color will be described.
When a voltage is applied between the common electrode 61 and the individual electrode 62 so that the common electrode 61 has a negative potential and the individual electrode 62 has a positive potential, an electric field is generated in the vertical direction (vertical direction) in FIG. By the action of this electric field, the white particles A and the black particles B migrate in the dispersion medium.

Specifically, since the white particles A are positively charged particles, they migrate toward the common electrode 61 side (upper side) so as to be electrically adsorbed by the common electrode 61 having a negative potential. Since one black particle B is a negatively charged particle, it migrates toward the individual electrode 62 side (lower side) so as to be electrically adsorbed by the individual electrode 62 having a positive potential.
If such a voltage application state (electric field generation state) is maintained, as shown in FIG. 4, the white particles A reach the ceiling surface (the lower surface of the sealing member 32) of the housing portion 4 and near the common electrode 61. Gather. Thereby, the color of the white particles A is visually recognized through the common electrode 61, and a white display state is obtained.

  One black particle B reaches the bottom 71 and further enters the groove 712. In such a state, since the light transmitted through the white particles A is reflected by the light reflecting surface 711 without being absorbed by the black particles B, the user of the electrophoretic display device 1 reflects the light from the white particles A. Since not only light but also reflected light from the light reflecting surface 711 is visually recognized, the brightness in white display is increased as a result. As a result, the brightness and contrast of the white display of the electrophoretic display device 1 can be increased.

  Further, since the black particles B can be accommodated in the grooves 712 during the white display and the black particles B can be hidden (not noticeable), a bright white display is performed even if the thickness of the accommodating portion 4 is reduced. be able to. Therefore, the electrophoretic display device 1 can be thinned (downsized) while increasing the brightness and display contrast of white display. Further, since the distance between the common electrode 61 and the individual electrode 62 is reduced by reducing the thickness, low voltage driving can be performed correspondingly, and power saving can be achieved.

  Moreover, since the height of the part which partitions the accommodating part 4 in the recessed part 7 can be made low, the process of the recessed part 7 becomes a simple thing and a yield improves. Further, by reducing the height of the portion that partitions the accommodating portion 4 in the concave portion 7, the strength can be increased, and a highly reliable device can be obtained. Further, when the strength of the portion that partitions the accommodating portion 4 in the concave portion 7 is sufficiently secured, the thickness of the portion that partitions the accommodating portion 4 in the concave portion 7 can be reduced accordingly, and the area of the accommodating portion 4 is increased. It is possible to further increase the brightness of the white display.

≪Black display state≫
Next, a state in which black (the color of the black particles B) is visually recognized as the display color will be described.
For example, after the white display state described above, the voltage is applied between the common electrode 61 and the individual electrode 62 so that the common electrode 61 has a positive potential and the individual electrode 62 has a negative potential. Then, an electric field is generated in the vertical direction (vertical direction) in FIG. By the action of the electric field, the white particles A and the black particles B migrate in the liquid phase dispersion medium.

Specifically, the black particles B migrate toward the common electrode 61 so as to be electrically adsorbed by the common electrode 61 having a positive potential. One white particle A migrates toward the individual electrode 62 side so as to be electrically adsorbed by the individual electrode 62 having a negative potential.
When such a voltage application state is maintained, the black particles B gather near the common electrode 61 as shown in FIG. Thereby, the color of the black particle B is visually recognized through the common electrode 61, and a black display state is obtained. Since the black particles B hardly transmit light, the light reflection surface 711 does not impair the display contrast.

  One white particle A collects in the vicinity of the individual electrode 62. Here, the outer shape of the white particles A is larger than the width of the groove 712. Therefore, the white particles A cannot enter the groove 712 and are unevenly distributed on the light reflecting surface 711, for example. Thus, by preventing the white particles A from entering the grooves 712, the white particles A can be prevented from sticking to the inner walls of the grooves 712. As a result, (1) the space for accommodating the black particles B is reduced, and depending on the size of the grooves 712, all the black particles B cannot be accommodated in the grooves 712, or (2) they are actually accommodated. The number of white particles A that can migrate in the portion 4 is reduced, and it is possible to reliably prevent bright white display from being performed depending on the number and particle size of the white particles A.

As described above, the electrophoretic display device 1 prevents a change in display color over time while reducing power consumption, and enables bright white display and high contrast display.
In such a configuration, by controlling the migration of the white particles A and the black particles B for each storage unit 4, the reflected light from the white particles A and the black particles B is reflected on the display surface side of the electrophoretic display device 1. Based on this, desired information (image) is displayed.

-Manufacturing method of electrophoretic display device 1-
Below, the manufacturing method of the electrophoretic display device 1 is demonstrated.
6 and 7 are cross-sectional views for explaining a method for manufacturing the electrophoretic display device 1.
First, as shown in FIG. 6A, a substrate 910 to be the separation member 31 is prepared. Then, a resist mask 920 is formed so as to leave a portion where the light reflecting surface 711 is formed on the upper surface 911 of the substrate 910.

Next, an aluminum thin film is formed on the upper surface of the substrate 910 through a resist mask 920 by various film formation methods such as vacuum evaporation, sputtering, and CVD. Thereafter, by removing the resist mask 920, a light reflecting surface 711 is formed on the upper surface 911 of the substrate 910 as shown in FIG. 6B.
Next, as shown in FIG. 6C, the substrate 910 is mounted on a mounting table including a heater (not shown), and the substrate 910 is heated by the heater. In a state where the substrate 910 is heated, a mold 930 corresponding to the shape of the recess 7, the light reflecting surface 711, and the groove 712 (that is, the shared space S1 and the accommodation space S2) is applied to the substrate 910 from above with a predetermined pressure. Press. As a result, as shown in FIG. 6D, a substrate 910 having the recesses 7, the light reflecting surfaces 711, and the grooves 712 is obtained.

Next, as shown in FIG. 7A, an electrophoretic dispersion liquid 10 in which white particles A and black particles B are dispersed in a liquid phase dispersion medium is injected into each recess 7. The electrophoresis dispersion liquid 10 can be injected using, for example, a dispenser.
Next, as shown in FIG. 7B, a transparent sheet member 940 that becomes the sealing member 32 is bonded to the substrate 910 so as to close the upper opening of the recess 7. Thereby, the recessed part 7 is sealed and the some accommodating part 4 with which the electrophoretic dispersion liquid 10 was filled is formed. As a result, the display layer 5 is obtained. The substrate 910 and the sheet member 940 can be bonded with, for example, an adhesive.
Next, as shown in FIG. 7C, the common electrode 61 is formed on the upper surface of the sheet member 940, and the individual electrode 62 (individual electrode piece) formed on the lower surface of the substrate 910 so as to correspond to the accommodating portion 4. The electrophoretic display device 1 is obtained by pasting the circuit board 8 provided with 621).

<Second Embodiment>
Next, a second embodiment of the electrophoretic display device of the present invention will be described.
FIG. 8 is a longitudinal sectional view schematically showing a second embodiment of the electrophoretic display device of the invention. In the following description, the upper side of FIG. 8 is referred to as “upper” and the lower side is referred to as “lower”.
Hereinafter, the electrophoretic display device according to the second embodiment will be described. The description will focus on the differences from the first embodiment, and description of similar matters will be omitted.
The electrophoretic display device according to this embodiment is the same as that of the first embodiment except that a colored portion is provided instead of the light reflecting surface.

As shown in FIG. 8, the bottom part (laying part) 71 of the electrophoretic display device 1 of the present embodiment has a surface 713 that faces the shared space S1, and a groove 712 that communicates (opens) to the shared space S1. Yes. Since the groove 712 is the same as that of the first embodiment described above, the description thereof is omitted.
In the present embodiment, the surface 713 is white. Thereby, in the white display (that is, the state in which the white particles A are gathered on the common electrode 61 side and the black particles B are accommodated in the grooves 712), the light is incident from the common electrode 61 side and transmitted through the white particles A. The scattered light is scattered (diffused) on the white surface 713 without being absorbed by the black particles B, so that the user of the electrophoretic display device 1 can only use the reflected light (scattered light) from the white particles A. In addition, since scattered light from the surface 713 is also visually recognized, the brightness in white display is increased as a result. As a result, the brightness and display contrast of the white display of the electrophoretic display device 1 can be increased.

The color of the surface 713 is not particularly limited as long as it has a lightness higher than that of the black particles (second electrophoretic particles) B, and may be yellow, green, red, or the like. The white color described above is preferable from the viewpoint of excellent light scattering properties.
The electrophoretic display device 1 according to the present embodiment as described above exhibits the same operations and effects as the first embodiment.

<Third Embodiment>
Next, a third embodiment of the electrophoretic display device of the present invention will be described.
FIG. 9 is a longitudinal sectional view schematically showing a third embodiment of the electrophoretic display device of the invention.
Hereinafter, the electrophoretic display device according to the second embodiment will be described. The description will focus on the differences from the first embodiment, and description of similar matters will be omitted.
The electrophoretic display device according to this embodiment is the same as that of the first embodiment except that the configuration of the groove 712 is different.

As shown in FIG. 9, each x-axis direction extending groove 712x is formed so that the depth direction is inclined with respect to the migration direction (z-axis direction) of the white particles A and the black particles B. The same applies to each y-axis direction extending groove 712y. Thereby, when the inside of the accommodating part 4 is visually recognized from the common electrode 61 side, the inside of the groove 712 becomes less visible. For this reason, the black particles B housed in the grooves 712 are also less noticeable. As a result, the brightness and display contrast of white display can be further increased.
The electrophoretic display device 1 according to the present embodiment as described above exhibits the same operations and effects as the first embodiment.

<Electronic equipment>
The electrophoretic display device 1 as described above can be incorporated into various electronic devices. Hereinafter, the electronic apparatus of the present invention including the electrophoretic display device 1 will be described.
<< Electronic Paper >>
First, an embodiment when the electronic apparatus of the present invention is applied to electronic paper will be described.
FIG. 10 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.
An electronic paper 600 shown in FIG. 10 includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602.
In such an electronic paper 600, the display unit 602 includes the electrophoretic display device 1 as described above.

<< Display >>
Next, an embodiment when the electronic apparatus of the present invention is applied to a display will be described.
FIG. 11 is a diagram showing an embodiment when the electronic apparatus of the present invention is applied to a display. 11A is a cross-sectional view, and FIG. 11B is a plan view.
A display (display device) 800 shown in FIG. 11 includes a main body 801 and an electronic paper 600 that is detachably attached to the main body 801. The electronic paper 600 has the same configuration as described above, that is, the configuration shown in FIG.

  The main body 801 has an insertion port 805 into which the electronic paper 600 can be inserted on its side (right side in FIG. 11A), and two pairs of conveying rollers 802a and 802b are provided inside. Yes. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the transport roller pairs 802a and 802b.

  A rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in FIG. 11B), and a transparent glass plate 804 is fitted in the hole 803. . Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.

In addition, a terminal portion 806 is provided at the distal end portion (left side in FIG. 11) of the electronic paper 600 in the insertion direction, and the terminal is provided inside the main body portion 801 with the electronic paper 600 installed on the main body portion 801. A socket 807 to which the unit 806 is connected is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.
In such a display 800, the electronic paper 600 is detachably installed on the main body 801, and can be carried and used while being detached from the main body 801.
In such a display 800, the electronic paper 600 is configured by the electrophoretic display device 1 as described above.

  Note that the electronic apparatus of the present invention is not limited to the application to the above, and for example, a television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, an electronic Examples include newspapers, word processors, personal computers, workstations, videophones, POS terminals, and devices equipped with touch panels. The electrophoretic display device of the present invention can be applied to the display units of these various electronic devices. Is possible.

The electrophoretic display sheet, electrophoretic display device, and electronic apparatus of the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each part has the same function. Can be replaced with any structure having In addition, any other component may be added to the present invention.
In the above-described embodiment, the separation member has been described in which the bottom portion (laying portion) of the recess and the partition wall that separates the storage portions are integrally formed. After forming the bottom part (laying part) and each wall as separate bodies, the separating member may be formed by joining them.

1 is a longitudinal sectional view schematically showing a first embodiment of an electrophoretic display device of the present invention. FIG. 2 is an enlarged plan view showing a bottom part included in the electrophoretic display device of FIG. 1. FIG. 2 is a schematic enlarged view of light reflecting particles provided in the electrophoretic display device shown in FIG. 1. It is sectional drawing explaining the action | operation of the electrophoretic display device shown in FIG. It is sectional drawing explaining the action | operation of the electrophoretic display device shown in FIG. It is sectional drawing explaining the manufacturing method of the electrophoretic display device shown in FIG. It is sectional drawing explaining the manufacturing method of the electrophoretic display device shown in FIG. It is a longitudinal section showing a 2nd embodiment of an electrophoretic display device of the present invention typically. It is a longitudinal cross-sectional view which shows typically 3rd Embodiment of the electrophoretic display device of this invention. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is a figure which shows embodiment at the time of applying the electronic device of this invention to a display.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electrophoretic display device 2 ... Electrophoretic display sheet 31 ... Separation member 32 ... Sealing member 4 ... Storage part 5 ... Display layer 61 ... Common electrode 62 ... Individual electrode 621 ... Electrode piece 7: Recessed portion 71: Bottom portion (laying portion) 711: Light reflecting surface 711a: Unit light reflecting surface 712 ... Groove 712x ... x-axis direction extending groove 712y ... y-axis direction extending groove 713 ... Surface 8 …… Circuit substrate (back plane) 81 …… Base 910 …… Substrate 911 …… Top surface 920 …… Resist mask 930 …… Mold 940 …… Sheet member 10 …… Electrophoretic dispersion liquid A …… First Electrophoretic particles B ... Second electrophoretic particles S1 ... Shared space S2 ... Accommodating space 600 ... Electronic paper 601 ... Main body 602 ... Display unit 800 ... Display 801 ... Body portion 802a, 802b ‥‥ conveying roller pair 803 ‥‥ hole 804 ‥‥ transparent glass plate 805 ‥‥ insertion opening 806 ‥‥ terminal portion 807 ‥‥ socket 808 ‥‥ controller 809 ‥‥ operating unit

Claims (22)

First electrophoretic particles charged positively or negatively;
A second electrophoretic particle that is charged to the opposite polarity to the first electrophoretic particle and has a lighter color than the first electrophoretic particle;
A shared space in which the first electrophoretic particles and the second electrophoretic particles can migrate to each other;
A storage space that communicates with the shared space and stores the second electrophoretic particles;
A light reflecting surface having a metallic luster provided adjacent to the accommodation space;
An electrophoretic display sheet comprising: a pair of electrodes opposed to each other with the shared space and the accommodation space interposed therebetween.   2. A laying portion having a surface facing the accommodation space and a groove opened to the surface, wherein the surface of the laying portion constitutes the light reflecting surface, and the groove constitutes the accommodation space. The electrophoretic display sheet described in 1.   The electrophoretic display sheet according to claim 2, wherein the light reflecting surface is provided so as to be orthogonal to a migration direction of the first electrophoretic particles and the second electrophoretic particles.   The electrophoretic display sheet according to claim 2, wherein a depth direction of the groove is parallel to a migration direction of the first electrophoretic particles and the second electrophoretic particles.   The electrophoretic display sheet according to claim 2 or 3, wherein a depth direction of the groove is inclined with respect to a migration direction of the first electrophoretic particles and the second electrophoretic particles.   The electrophoretic display sheet according to claim 2, wherein a depth of the groove is larger than an outer diameter of the second particle.   The electrophoretic display sheet according to claim 2, wherein a width of the groove is larger than an outer diameter of the second electrophoretic particle and smaller than an outer diameter of the first electrophoretic particle.   The electrophoretic display sheet according to claim 2, wherein the grooves are formed in a lattice shape. First electrophoretic particles charged positively or negatively;
A second electrophoretic particle that is charged to the opposite polarity to the first electrophoretic particle and has a lighter color than the first electrophoretic particle;
A shared space in which the first electrophoretic particles and the second electrophoretic particles can migrate to each other;
A storage space that communicates with the shared space and stores the second electrophoretic particles;
A surface provided adjacent to the housing space and having a lightness higher than the lightness of the color of the second electrophoretic particles;
An electrophoretic display sheet comprising: a pair of electrodes opposed to each other with the shared space and the accommodation space interposed therebetween.   The electrophoretic display sheet according to claim 9, wherein the colored surface is white.   A laying portion having a surface facing the housing space and a groove opened to the surface, wherein the surface of the laying portion constitutes a surface having a lightness higher than the lightness of the color of the second electrophoretic particle The electrophoretic display sheet according to claim 9, wherein the groove constitutes the housing space.   The electrophoretic display sheet according to claim 11, wherein the colored surface is provided so as to be orthogonal to a migration direction of the first electrophoretic particles and the second electrophoretic particles.   The electrophoretic display sheet according to claim 11, wherein a depth direction of the groove is parallel to a migration direction of the first electrophoretic particles and the second electrophoretic particles.   The electrophoretic display sheet according to claim 11, wherein a depth direction of the groove is inclined with respect to a migration direction of the first electrophoretic particles and the second electrophoretic particles.   The electrophoretic display sheet according to claim 11, wherein a depth of the groove is larger than an outer diameter of the second particle.   The electrophoretic display sheet according to claim 11, wherein a width of the groove is larger than an outer diameter of the second electrophoretic particle and smaller than an outer diameter of the first electrophoretic particle.   The electrophoretic display sheet according to claim 11, wherein the grooves are formed in a lattice shape.   The electrophoretic display sheet according to claim 1, wherein the storage unit is configured to store only the second electrophoretic particles.   The electrophoretic display sheet according to claim 1, wherein the first electrophoretic particles are white particles, and the second electrophoretic particles are black particles.   An electrophoretic display device comprising: the electrophoretic display sheet according to claim 1; and a substrate provided on the accommodation space side of the electrophoretic display sheet.   A plurality of the accommodation spaces arranged in a planar shape are provided, and generation / cancellation of the electric field can be selected for each of one or more of the plurality of accommodation spaces. Item 20. The electrophoretic display device according to Item 20.   An electronic apparatus comprising the electrophoretic display device according to claim 21.

Images