WO2017149986A1 - Display device and electronic apparatus - Google Patents

Abstract

A display device according to an embodiment of the present disclosure comprises, in an insulating liquid, at least two kinds of electrophoretic particles having a selective optical transmission property; and a porous layer including a first layer and a second layer, wherein the first layer is formed of a fibrous structure, has a light transmitting property, and is disposed on a display surface side, and the second layer has an optical reflection property different from that of the electrophoretic particles, and is disposed on a rear surface side.

Description

Display device and electronic device

The present disclosure relates to a display device and an electronic apparatus that perform display using an electrophoresis phenomenon.

In order to realize color display with high saturation and lightness in an electrophoretic display using an electrophoretic phenomenon, it is necessary to conceal colored particles having a color other than the display color. As a method of concealing colored particles having a color other than the display color, for example, there is a method of increasing the diffuse reflectance of the colored particles to increase the particle concentration. Further, there is a method in which the colored particle concentration distribution peaks are arranged in the order of colored particles having a color desired to be displayed from the display surface side, white particles, and other color particles. In this method, light selected by colored particles having a color to be displayed is diffusely reflected by white particles. This makes it possible to display the color that the colored particles want to display, but in order to realize a desired permutation of particle distribution, complicated driving is required.

For this reason, a method for realizing the permutation of the particle distribution with a simple drive has been studied, and as an example, non-migrated white particles with high light hiding properties are arranged in the space from the transparent electrode to the back electrode, and the migration speed is increased. An electrophoretic display configuration using colored particles with differences has been found. In this electrophoretic display, it becomes easy to increase the distance between particles having a desired color and particles having other colors, and particles having other colors are efficiently concealed by non-electrophoretic white particles. Specifically, for example, in Patent Document 1, a plurality of types of charged particles having different colors and threshold voltages for starting migration as electrophoretic particles and a white holding body for holding the electrophoretic particles are used. An image display device is disclosed.

JP 2012-181507 A

Incidentally, an electrophoretic display capable of color display is required to have high color reproducibility in addition to high brightness and saturation.

It is desirable to provide a display device and an electronic device that can realize high color reproducibility.

A display device according to an embodiment of the present disclosure is formed of two or more kinds of migrating particles having selective optical transmission characteristics and a fibrous structure in an insulating liquid, and has light transmittance. A first layer disposed on the display surface side and a porous layer having an optical reflection characteristic different from that of the migrating particles and including a second layer disposed on the back surface side are provided.

An electronic apparatus according to an embodiment of the present disclosure includes the display device according to the embodiment of the present disclosure.

In a display device according to an embodiment of the present disclosure and an electronic apparatus according to an embodiment, the porous layer is configured by a plurality of layers, and a light-transmitting layer (first layer) is disposed on the display surface side. Accordingly, it is possible to prevent a decrease in saturation due to the migrating particles having a color desired to be displayed being concealed by the porous layer (second layer) having a light reflection characteristic different from that of the migrating particles.

According to the display device according to an embodiment of the present disclosure and the electronic apparatus according to the embodiment, the porous layer includes a plurality of layers, and the light-transmitting layer (first layer) is disposed on the display surface side. As a result, color display with high saturation becomes possible. That is, it is possible to provide a display device and an electronic device with high color reproducibility. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

It is sectional drawing showing the structure of the display apparatus which concerns on one embodiment of this indication. It is a plane schematic diagram of the display apparatus shown in FIG. FIG. 2 is a schematic plan view for explaining the electrophoretic element shown in FIG. 1. FIG. 2 is a cross-sectional view for explaining the operation of the display device shown in FIG. 1. FIG. 2 is a cross-sectional view for explaining the operation of the display device shown in FIG. 1. It is a figure showing the time change of the electric potential difference with respect to the display surface side of the back side of the display apparatus shown in FIG. It is a figure showing the time change of the average position of each migrating particle by the time change of the electric potential difference shown in FIG. 14 is a perspective view illustrating an appearance of application example 1. FIG. FIG. 7B is a perspective view illustrating another example of the electronic book illustrated in FIG. 7A. 12 is a perspective view illustrating an appearance of application example 2. FIG. 14 is a perspective view illustrating an example of an appearance of application example 3. FIG. 22 is a perspective view illustrating another example of the appearance of application example 3. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The order of explanation is as follows.
1. Embodiment (example in which a light-transmitting porous layer is provided on the display surface side)
1-1. Configuration of display device 1-2. Manufacturing method of display device 1-3. Operation of display device 1-4. Action / Effect Application example (electronic equipment)

<1. Embodiment>
FIG. 1 illustrates a cross-sectional configuration of a display device (display device 1) according to an embodiment of the present disclosure. FIG. 2 schematically shows a planar configuration of the main part of the display device 1. FIG. 1 shows a cross section taken along line II in FIG. The display device 1 is an electrophoretic display that generates contrast using an electrophoretic phenomenon, and an electrophoretic element (electrophoretic element 30) is used as a display element. The display device 1 includes, for example, an electrophoretic element 30 as a display body between a drive substrate 10 and a counter substrate 20 that are arranged to face each other with a spacer 40 interposed therebetween. The electrophoretic element 30 includes a plurality of types of migrating particles 32 and a porous layer 33 composed of a fibrous structure 331 in an insulating liquid 31. In this embodiment, the porous layer 33 (here, two layers ( porous layer 33A, 33B)) a plurality of layers made of, a porous layer 33A having optical transparency on the display surface S ₁ side It has an arranged configuration. 1 and 2 schematically show the configuration of the display device 1 and may differ from actual dimensions and shapes.

(1-1. Configuration of display device)
In the display device 1, for example, as shown in FIG. 1, a drive substrate 10 and a counter substrate 20 are disposed so as to face each other with an electrophoretic element 30 therebetween, and a display surface S ₁ is provided on the counter substrate 20 side. is doing. The phrase “having a display surface on the counter substrate 20 side” means that an image is displayed toward the counter substrate 20 (the user can visually recognize an image from the counter substrate 20 side). Further, an adhesive layer 16 and an adhesive layer 23 are provided between the drive substrate 10 and the electrophoretic element 30 and between the counter substrate 20 and the electrophoretic element 30, respectively. The substrate 20 and the electrophoretic element 30 are bonded together.

For example, the driving substrate 10 has a thin film transistor (TFT) 12, a protective layer 13, a planarization insulating layer 14, and a pixel electrode 15 formed in this order on one surface of a support base 11. For example, the TFT 12 and the pixel electrode 15 are divided and formed in a matrix or segment according to a pixel pattern or the like.

The support base 11 is made of, for example, an inorganic material, a metal material, a plastic material, or the like. Examples of the inorganic material include silicon (Si), silicon oxide (SiO _x ), silicon nitride (SiN _x ), and aluminum oxide (AlO _x ). Silicon oxide includes glass or spin-on-glass (SOG). Examples of the metal material include aluminum (Al), nickel (Ni), and stainless steel, and examples of the plastic material include polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethyl ether. Examples include ketone (PEEK), cycloolefin polymer (COP), polyimide (PI), and polyethersulfone (PES).

The support substrate 11 may be light transmissive or non-light transmissive. This is because the image is displayed on the counter substrate 20 side, and thus the support base 11 does not necessarily need to be light transmissive. The support base 11 may be a rigid substrate such as a wafer, or may be composed of a flexible thin glass or film. By using a flexible material for the support base 11, a flexible display device 1 can be realized.

TFT 12 is a switching element for selecting a pixel. The TFT 12 may be an inorganic TFT using an inorganic semiconductor layer as a channel layer, or an organic TFT using an organic semiconductor layer. Examples of the material for the inorganic semiconductor layer include amorphous silicon, polysilicon, and oxide. Examples of the material for the organic semiconductor layer include pentacene. The protective layer 13 and the planarization insulating layer 14 are made of an insulating resin material such as polyimide, for example. If the surface of the protective layer 13 is sufficiently flat, the planarization insulating layer 14 can be omitted. The pixel electrode 15 is formed of a metal material such as gold (Au), silver (Ag), or copper (Cu), for example. The pixel electrode 15 is connected to the TFT 12 through a contact hole (not shown) provided in the protective layer 13 and the planarization insulating layer 14.

Note that FIG. 1 shows a case where, for example, the TFT 12 is arranged for each cell 36 described later (one TFT 12 is provided for one cell 36). However, the present invention is not necessarily limited to this, and the numbers and positional relationships of the cells 36 and the TFTs 12 may be arbitrary. For example, two TFTs 12 may be arranged for three cells 36, or a boundary between two adjacent TFTs 12 may be located within the range of the cell 36.

The adhesive layer 16 is for bonding the drive substrate 10 and the partition unit 38, and is made of, for example, acrylic resin, urethane resin, rubber, or the like, and has a film thickness of, for example, 1 μm to 100 μm.

The counter substrate 20 includes, for example, a support base 21 and a counter electrode 22, and the counter electrode 22 is provided on the entire surface of the support base 21 (a surface facing the drive substrate 10). The counter electrode 22 may be arranged in a matrix or segment like the pixel electrode 15.

The support base 21 is made of the same material as the support base 11 except that it is light transmissive. For the counter electrode 22, for example, a light-transmitting conductive material such as indium oxide-tin oxide (ITO), antimony oxide-tin oxide (ATO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO). (Transparent electrode material). The film thickness of the support base 21 is, for example, 1 μm to 250 μm.

When displaying an image on the counter substrate 20 side, since the display device (electrophoretic element 30) is viewed through the counter electrode 22, the light transmittance (transmittance) of the counter electrode 22 should be as high as possible. For example, 80% or more. Examples of such a material include indium oxide-tin oxide (ITO), antimony oxide-tin oxide (ATO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO). The thickness of the counter electrode 22 is, for example, 0.001 μm to 1 μm. Further, the electrical resistance of the counter electrode 22 is preferably as low as possible, for example, 100Ω / □ or less. Although the example in which the counter electrode 22 is formed on the entire surface of the support base 21 is shown in FIG. 1, similarly to the pixel electrode 15, for example, the counter electrode 22 may be formed separately for each pixel.

The adhesive layer 23 is for bonding the counter substrate 20 and the partition unit 38 (particularly, the partition 35), and is made of, for example, acrylic resin, urethane resin, or rubber, and has a film thickness of, for example, 1 μm to 100 μm. is there.

In addition, although the example which provided the contact bonding layer 23 in the whole surface of the counter electrode 22 was shown here, you may make it provide only in the contact part with the partition 35. FIG. Further, a seal layer and a color filter may be laminated on the counter substrate 20. Furthermore, a film having a conductive layer may be used as the counter substrate 20. Furthermore, a moisture-proof film or the like that prevents intrusion of moisture or the like may be provided on the display surface side of the support base 21.

As shown in FIGS. 1 and 3, the electrophoretic element 30 includes a plurality of types of migrating particles 32 (here, three types of migrating particles 32 </ b> C, 32 </ b> M, and 32 </ b> Y) and a plurality of layers in an insulating liquid 31. The porous layer 33 (here, two layers, porous layers 33A and 33B) is provided. The migrating particles 32C, 32M, and 32Y are dispersed in the insulating liquid 31. The porous layer 33A is configured using the fibrous structure 331 and has light transmittance. The porous layer 33B includes a fibrous structure 331 and non-migrating particles 332, and has an optical reflection characteristic different from that of the migrating particles 32C, 32M, and 32Y. Each of the porous layers 33A and 33B has one or two or more pores 333, and one or two or more partition walls 35 are formed on the porous layer 33 from the opposite side (drive substrate 10 side) of the display surface. Adjacent.

The insulating liquid 31 is filled in a space between the drive substrate 10 and the counter substrate 20, for example. The insulating liquid 31 is composed of, for example, any one or two or more kinds of non-aqueous solvents such as organic solvents, and specifically includes hydrocarbon solvents such as paraffin. It is preferable to make the viscosity and refractive index of the insulating liquid 31 as low as possible. When the viscosity of the insulating liquid 31 is lowered, the mobility (response speed) of the migrating particles 32 is improved. In accordance with this, the energy (power consumption) required to move the migrating particles 32 is reduced. When the refractive index of the insulating liquid 31 is lowered, the difference in refractive index between the insulating liquid 31 and the porous layer 33 is increased, and the reflectance of the porous layer 33 is increased. Note that a weak conductive liquid may be used instead of the insulating liquid 31.

The insulating liquid 31 may contain other various materials as necessary. For example, a colorant, a charge adjusting agent, a dispersion stabilizer, a viscosity adjusting agent, a surfactant or a resin may be added.

The electrophoretic particles 32 are one or more charged particles (electrophoretic particles) that migrate electrically, and are displayed by moving in the insulating liquid 31 toward the pixel electrode 15 or the counter electrode 22 in accordance with an electric field. An image is displayed on the surface. The migrating particles 32 are made of particles (powder) such as organic pigments, inorganic pigments, pigments, carbon materials, metal materials, metal oxides, glass, or polymer materials (resins). As the electrophoretic particles 32, one of these may be used, or two or more of them may be used. The electrophoretic particles 32 may be pulverized particles or capsule particles of resin solids containing the above particles. Note that materials corresponding to the carbon material, metal material, metal oxide, glass, or polymer material are excluded from materials corresponding to organic pigments, inorganic pigments, or pigments. The particle size of the migrating particles 32 is, for example, in the range of not less than 100 nm and not more than 5 μm.

As described above, the migrating particle 32 of the present embodiment has the three types of migrating particles 32C, 32M, and 32Y. The kind here is an average migration speed of the migrating particles 32 in the insulating liquid 31 when a potential difference is generated between the display surface S ₁ and the back surface S ₂ . The migration speed of the migrating particles 32 is determined by, for example, the charge amount of the migrating particles 32, and the migration speed increases as the charge amount increases. The charge amount varies depending on, for example, the particle size of the migrating particles 32. The larger the particle size, the larger the charge amount.

The three types of migrating particles 32C, 32M, and 32Y used in the present embodiment are charged particles having the same charge (same polarity), and, for example, the migrating particle 32C is the fastest, and then the migrating particle 32M. And the migrating particle 32Y is the slowest of the three types of migrating particles. Therefore, the average particle diameters of the migrating particles 32C, 32M, and 32Y are, for example, 1.8 μm (migrating particle 32C), 0.6 μm (migrating particle 32M), and 0.2 μm (migrating particle 32Y). The average particle size of each of the migrating particles 32C, 32M, and 32Y is not limited to the above value. For example, the smaller migrating particles have an average particle size a ₁ and a particle size dispersion value σ ₁ and a larger migrating particle. If the particles in an average particle size of a ₂ and a particle size distribution value sigma _2, may be a relationship between _{a 1 -2σ 1> a 2 +} 2σ 2.

The electrophoretic particles 32C, 32M, and 32Y each have transmission characteristics (selective optical transmission characteristics) that selectively transmit arbitrary color light. The optical transmission characteristics of the migrating particles 32C, 32M, and 32Y are not particularly limited, but are preferably set so that the porous layer 33 can be shielded at least during black display. This is because the contrast is generated by utilizing the selective light transmission of the migrating particles 32C, 32M, and 32Y and the light reflection of the porous layer 33. In the present embodiment, the migrating particles 32C, 32M, and 32Y absorb light in different wavelength ranges. Specifically, the migrating particle 32C selectively absorbs, for example, cyan complementary color light and exhibits a cyan color as a display color. For example, the migrating particle 32M selectively absorbs magenta complementary color light and exhibits a magenta color as a display color. For example, the migrating particle 32Y selectively absorbs yellow complementary color light and exhibits yellow as a display color.

In the display device 1 of the present embodiment, cyan, magenta, and yellow are displayed by the migrating particles 32C, 32M, and 32Y, and black display is provided by a subtractive color mixture of the migrating particles 32C, 32M, and 32Y. White display is made by the quality layer 33.

Examples of the material constituting the migrating particles 32C, the migrating particles 32M, and the migrating particles 32Y include pigments that exhibit corresponding colors. Specific materials include, for example, quinacridone, perylene, perinone, isoindolinone, dioxazine, isoindoline, anthraquinone, quinophthalone, diketopyrrolopyrrole and other polycyclic pigments, phthalocyanine pigments, azo lake red, azo lake red, piazolone, Examples thereof include azo pigments such as disazo, monoazo, condensed azo, naphthol, and pendimidazolone, and inorganic pigments such as cadmium yellow, strontium chromate, viridian, oxide chromium, cobalt blue, and ultramarine. These series of materials may be used alone or in combination of two or more.

The content (concentration) of the migrating particles 32 (32C, 32M, 32Y) in the insulating liquid 31 is not particularly limited, but the entire migrating particles 32 may be, for example, 0.1 wt% to 10 wt%. preferable. This is because the shielding and mobility of the migrating particles 32 are ensured. For example, if the content of the migrating particles 32 is less than 0.1% by weight, the migrating particles 32 are difficult to shield the porous layer 33, and there is a possibility that sufficient contrast cannot be generated. On the other hand, if the content of the migrating particles 32 is more than 10% by weight, the dispersibility of the migrating particles 32 is lowered, so that the migrating particles 32 are difficult to migrate and may aggregate. The content (concentration) of the electrophoretic particles 32C, 32M, and 32Y colored in the respective colors depends on the particle size, but for example, the electrophoretic particle 32C having the largest particle size has a weight of 0.1 to 4% by weight, and the following. In the case of the larger migrating particles 32M, it is preferably 0.1% by weight to 4% by weight, and in the next larger migrating particle 32Y, it is preferably 0.1% by weight to 4% by weight. However, it is desirable to change the weight ratio of each particle according to the expected display characteristics, color gamut, and contrast.

It is preferable that the migrating particles 32C, 32M, and 32Y are easily dispersed and charged in the insulating liquid 31 over a long period of time and are difficult to be adsorbed to the porous layer 33. For this reason, a dispersing agent (or charge adjusting agent) for dispersing the electrophoretic particles 32C, 32M, and 32Y by electrostatic repulsion may be used, or surface treatment may be applied to the electrophoretic particles 32C, 32M, and 32Y. May be.

This dispersing agent or charge adjusting agent has, for example, either positive or negative charge, or both, and increases the amount of charge in the insulating liquid 31. Examples of such a dispersant include Solsperce series manufactured by Lubrizol, BYK series or Anti-Terra series manufactured by BYK-Chemic, and Span series manufactured by TCI America.

The surface treatment is, for example, rosin treatment, surfactant treatment, pigment derivative treatment, pulling agent treatment, graft polymerization treatment or microencapsulation treatment. In particular, long-term dispersion stability of the migrating particles 32C, 32M, and 32Y can be maintained by performing a graft polymerization process, a microencapsulation process, or a combination thereof.

For such surface treatment, for example, a material (adsorbent material) having a functional group (adsorptive functional group) that can be adsorbed on the surface of the migrating particles 32C, 32M, and 32Y and a polymerizable functional group is used. The adsorptive functional group is determined according to the forming material of the migrating particles 32C, 32M, and 32Y. For example, when the migrating particles 32C, 32M, and 32Y are made of a carbon material such as carbon black, an aniline derivative such as 4-vinylaniline and the migrating particles 32C, 32M, and 32Y are made of a metal oxide. In some cases, organosilane derivatives such as 3- (trimethoxysilyl) propyl methacrylate can be adsorbed. Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group.

A polymerizable functional group may be introduced on the surface of the migrating particles 32C, 32M, and 32Y and grafted onto the surface to perform surface treatment (graftable material). The graft material has, for example, a polymerizable functional group and a dispersing functional group. The dispersion functional group disperses the migrating particles 32C, 32M, and 32Y in the insulating liquid 31, and retains dispersibility due to the steric hindrance. For example, when the insulating liquid 31 is paraffin, a branched alkyl group or the like can be used as the functional group for dispersion. Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group. In order to polymerize and graft the graft material, for example, a polymerization initiator such as azobisisobutyronitrile (AIBN) may be used. In addition, a material having a functional group that can be adsorbed on the surface of the migrating particles 32C, 32M, and 32Y and an alkyl chain for imparting dispersibility can be used. Examples of such materials include titanate and pulling agents (for example, KR-TTS manufactured by Ajinomoto Fine Techno Co., Ltd.) and aluminate and pulling agents.

For details of the method of dispersing the electrophoretic particles 32C, 32M, and 32Y in the insulating liquid 31, see “Ultrafine Particle Dispersion Technology and its Evaluation—Surface Treatment / Fine Grinding and Dispersion in Air / Liquid / Polymer”. Stabilization-(Science & Technology) "and other books.

As shown in FIG. 1, the porous layer 33 has a two-layer structure of a porous layer 33A and a porous layer 33B. As shown in FIGS. 1 and 3, the porous layer 33 is a three-dimensional structure (irregular network structure such as a non-woven fabric) formed of a fibrous structure 331, and is one or two or more. Gap (pore 333). The pore 333 is filled with the insulating liquid 31, and the migrating particles 32 </ b> C, 32 </ b> M, and 32 </ b> Y move between the pixel electrode 15 and the counter electrode 22 through the pore 333. The porous layer 33 may be adjacent to the counter electrode 22 or may be separated from it. The electrophoretic element 30 shown in FIG. 3 is a simplified representation of the porous layer 33B.

The fibrous structure 331 is a fibrous substance having a sufficiently large length with respect to the fiber diameter (diameter). The shape (external appearance) of the fibrous structure 331 is not particularly limited as long as the fibrous structure 331 has a fibrous shape that is sufficiently long with respect to the fiber diameter as described above. Specifically, it may be linear, may be curled, or may be bent in the middle. Moreover, you may branch to 1 or 2 or more directions on the way, not only extending in one direction. The formation method of the fibrous structure 331 is not particularly limited. For example, a phase separation method, a phase inversion method, an electrostatic (electric field) spinning method, a melt spinning method, a wet spinning method, a dry spinning method, a gel spinning method, A sol-gel method or a spray coating method is preferred. This is because a fibrous substance having a sufficiently large length with respect to the fiber diameter can be easily and stably formed.

The average fiber diameter of the fibrous structure 331 is not particularly limited, but is preferably as small as possible. This is because light easily diffuses and the average pore diameter of the pores 333 increases. However, the average fiber diameter is, for example, preferably a fiber diameter that allows the fibrous structure 331 to hold non-electrophoretic particles 332 described later, and is preferably 10 μm or less, for example. In addition, although the minimum of an average fiber diameter is not specifically limited, For example, it is 0.1 micrometer and may be less than that. This average fiber diameter is measured, for example, by microscopic observation using a scanning electron microscope (SEM) or the like. Note that the average length of the fibrous structure 331 may be arbitrary.

The fibrous structure 331 is preferably a nanofiber. Here, the nanofiber is a fibrous substance having a fiber diameter of 0.001 μm to 0.1 μm and a length of 100 times or more of the fiber diameter. By using such a nanofiber as the fibrous structure 331, light is easily irregularly reflected, and the reflectance of the porous layer 33 can be further improved. That is, the contrast of the electrophoretic element 30 can be improved. Further, in the fibrous structure 331 made of nanofibers, the proportion of the pores 333 in the unit volume increases, and the migrating particles 32 can easily move through the pores 333. Therefore, the energy required for moving the migrating particles 32 can be reduced. The fibrous structure 331 made of nanofibers is preferably formed by an electrostatic spinning method. By using the electrostatic spinning method, the fibrous structure 331 having a small fiber diameter can be easily and stably formed.

The fibrous structure 331 is formed of, for example, any one kind or two or more kinds of a polymer material or an inorganic material. Examples of the polymer material include nylon, polylactic acid, polyamide, polyimide, polyethylene terephthalate, polyacrylonitrile, polyethylene oxide, polyvinyl carbazole, polyvinyl chloride, polyurethane, polystyrene, polyvinyl alcohol, polysulfone, polyvinyl pyrrolidone, polyvinylidene fluoride, polyhexa Fluoropropylene, cellulose acetate, collagen, gelatin, chitosan or copolymers thereof. The inorganic material is, for example, titanium oxide. Among these, a polymer material is preferable as a material for forming the fibrous structure 331. This is because the reactivity (photoreactivity, etc.) is low (chemically stable), so that an unintended decomposition reaction of the fibrous structure 331 is suppressed. Note that in the case where the fibrous structure 331 is formed of a photoreactive material, the surface of the fibrous structure 331 is preferably covered with an arbitrary protective layer.

The fibrous structure 331 preferably has an optical reflection characteristic different from that of the migrating particles 32C, 32M, and 32Y. Specifically, the light reflectance of the fibrous structure 331 is not particularly limited, but is set so that at least the porous layer 33 can conceal the migrating particles 32C, 32M, and 32Y as a whole when displaying white. It is preferred that This is because contrast is generated by utilizing the difference between the light reflectance of the migrating particles 32C, 32M, and 32Y and the light reflectance of the porous layer 33. However, in this embodiment, the porous layer 33, as described above, has a two-layer structure in which a porous layer 33A and a porous layer 33B are arranged in this order from the display surface S ₁ side, the display surface S _The porous layer 33A disposed on the ₁ side has light transmittance. Therefore, the fibrous structure 331 itself preferably has light transmittance (colorless and transparent) in the insulating liquid 31, and the reflectance of the fibrous structure 331, that is, the reflectance of the entire porous layer 33 is It is preferably determined substantially by non-electrophoretic particles 332 described later.

As described above, the porous layer 33 according to the present embodiment has the light-transmitting porous layer 33A disposed on the display surface S ₁ side, and the back surface S ₂ side has optical reflection characteristics. The layer 33B is arranged. The porous layer 33A is formed of a fibrous structure 331 having light permeability, and includes one or more pores 333. The porous layer 33B is formed of a fibrous structure holding one or more non-migrating particles 332 having optical reflection characteristics different from the migrating particles 32C, 32M, and 32Y, and is similar to the porous layer 33A. In addition, one or two or more pores 333 are included. The reason why the non-migrating particles 332 are included in the fibrous structure 331 that constitutes the porous layer 33B is that external light is more likely to be diffusely reflected, and thus the light reflectance of the porous layer 33 is higher. . Thereby, contrast becomes higher.

The non-migrating particles 332 are one or more particles that are fixed to the fibrous structure 331 and do not migrate electrically. The non-migrating particles 332 may be embedded in the held fibrous structure 331 or may partially protrude from the fibrous structure 331.

The non-migrating particles 332 have optical reflection characteristics different from those of the migrating particles 32C, 32M, and 32Y. The light reflectance of the non-migrating particles 332 is not particularly limited, but is preferably set so that at least the porous layer 33 can conceal the migrating particles 32C, 32M, and 32Y as a whole. This is because contrast is generated by utilizing the difference between the light reflectance of the migrating particles 32C, 32M, and 32Y and the light reflectance of the porous layer 33.

Here, the specific forming material of the non-migrating particles 332 is selected according to the role played by the non-migrating particles 332 in order to generate contrast, for example. For example, when the porous layer 33 (specifically, the non-electrophoretic particle 332) is responsible for white display, for example, a metal oxide is preferable, and titanium oxide is more preferable. This is because it is excellent in electrochemical stability and fixability, and high reflectance can be obtained. If the contrast can be generated, the forming material of the non-migrating particles 332 may be the same type as the forming material of the migrating particles 32C, 32M, and 32Y, or may be a different type. Note that the non-migrating particles 332 may be a combination of two or more types of particles having different particle sizes.

The fibrous structure 331 constituting the porous layer 33A preferably contains particles that do not reflect visible light (non-visible light particles). Examples of the particles that do not reflect visible light include titania (TiO ₂ ) having a particle size of 250 nm or less. This is because the retention performance of the migrating particles 32C, 32M, and 32Y in the porous layer 33A may be improved by containing the fibrous structure 331TiO ₂ .

In the porous layers 33A and 33B, which are three-dimensional solid structures, one fibrous structure 331 may be entangled randomly, or a plurality of fibrous structures 331 are gathered and randomly overlapped. Alternatively, both may be mixed.

The porous layers 33A and 33B are three-dimensional structures because the average pore diameter of the pores 333 is increased and the number thereof is increased, so that the migrating particles 32C, 32M, and 32Y easily pass through the pores 333. Because it becomes. As a result, the time required to move the migrating particles 32C, 32M, and 32Y is shortened, and the energy required to move the migrating particles 32C, 32M, and 32Y is also reduced. Further, in the porous layer 33B including the non-electrophoretic particles 332, external light is likely to be irregularly reflected (multiple scattering) due to the irregular three-dimensional structure, and the light reflectance of the porous layer 33B is increased. Thereby, even if the film thickness of the porous layer 33B is thin, a high contrast with the migrating particles 32C, 32M, and 32Y can be obtained, and energy necessary for moving the migrating particles 32C, 32M, and 32Y can be suppressed. It becomes possible.

The pore 333 is formed by overlapping a plurality of fibrous structures 331 or entwining one fibrous structure 331. The average pore diameter of the pores 333 is not particularly limited, but is preferably as large as possible so that the migrating particles 32C, 32M, and 32Y can easily move through the pores 333. For this reason, the average pore diameter of the pores 333 is preferably 0.1 μm or more and 10 μm or less.

The total film thickness (W ₀ ) of the porous layer 33 is not particularly limited, but is preferably 5 μm to 100 μm, for example. This is because the concealability of the porous layer 33 is enhanced, and the migrating particles 32 can easily pass through the pores 333. The film thicknesses of the porous layer 33A and the porous layer 33B are preferably determined as follows, for example. For example, the film thickness (W ₁ ) of the light-transmitting porous layer 33A is the same as the film thickness (W ₀ ) of the entire porous layer 33 (in this embodiment, the electrophoretic particles 32C, It is preferable to set a value obtained by dividing by (the three types of 32M and 32Y) (the film thickness (W ₀ ) of the entire porous layer 33 / the number of species of the migrating particles). Alternatively, for example, when the migration speeds of the migrating particles 32C, 32M, and 32Y are different from each other as in the present embodiment, the migrating speed of the migrating particle 32C that moves the fastest is V1, the migration that moves the second fastest. When the migration speed of the particles 32M is V2, and the migration speed of the migration particles 32Y moving the third fastest is V3, the film thickness (W ₁ ) of the first layer with respect to the film thickness (W ₀ ) of the entire porous layer 33 is The larger value of W ₀ × (V2 / V1) and W ₀ × (V3 / V2) is preferably the film thickness of the porous layer 33A. On the other hand, the film thickness (W ₂ ) of the porous layer 33B is obtained by subtracting the film thickness (W ₁ ) of the porous layer 33A obtained from the above calculation from the film thickness (W ₀ ) of the entire porous layer 33. Become. Accordingly, details will be described later, electrophoretic particles having a desired display color (e.g., electrophoretic particles 32M) even if accidentally migrate to some extent back S ₂ side from the display surface S _1, electrophoretic particles 32M porous layer It is possible to prevent hiding by 33 (specifically, the porous layer 33B having optical reflection characteristics).

The partition 35 partitions the possible range of the migrating particles 32C, 32M, and 32Y dispersed in the insulating liquid 31, and accommodates the migrating particles 32C, 32M, and 32Y as shown in FIGS. A space (cell 36 to be described later) is formed. For example, the partition wall 35 extends toward the counter substrate 20 and is adjacent to a part of the porous layer 33 from the opposite side of the display surface. By accommodating the migrating particles 32C, 32M, and 32Y in the partition wall 35, it is possible to prevent the migrating particles 32C, 32M, and 32Y from being biased in the plane of the display device 1.

The number and arrangement pattern of the cells 36 formed by the partition walls 35 are not particularly limited. However, in order to efficiently arrange the plurality of cells 36, the cells 36 are preferably arranged in a matrix (arrangement of a plurality of rows and a plurality of columns). Further, the shape (opening shape) of the cell 36 is not particularly limited, and may be a rectangular shape as shown in FIG. 2 or another shape (such as a hexagon).

The material for forming the partition wall 35 is not particularly limited as long as it does not affect the operation performance of the electrophoretic element 30, but is preferably a resin that is excellent in molding. This is because it is easy to form the partition wall 35 having a desired size and shape. This resin is, for example, a thermoplastic resin or a photo-curing resin (including a resist for photolithography), and other resins may be used.

When a resin is used as the material for forming the partition wall 35, the partition wall 35 is formed by, for example, a thermal imprint method using a thermoplastic resin or a photo imprint method using a photocurable resin. . Specifically, in the thermal imprint method, for example, after a mold (female mold) is pressed onto a resin (polymer material) heated to a glass transition temperature or higher, the mold is peeled off from the cooled resin. Thereby, since the shape of a mold is transcribe | transferred to the surface of resin, the partition 35 which has a desired shape is formed. This mold may be, for example, a photoresist film formed by a photolithography method, or a metal plate formed by machining such as a cutting tool.

The partition wall 35 may have a support body 37 that is continuous with the drive substrate 10, and the partition wall 35 may be supported by the support body 37. In this case, the partition and support 37 may be unitized (partition unit 38). However, the partition wall 35 and the support body 37 may be integrated or separated. In the latter case, the support 37 may be a film or the like.

The width of the partition wall 35 in the X-axis direction may be uniform or non-uniform in the extending direction. For example, the width is preferably gradually reduced toward the porous layer 33. This is because the opening range (R3) of the cell 36 is widened toward the display surface side, and the immovable region (R4) of the migrating particles 32 is narrowed accordingly, so that the image display range is widened. The inclination angle (so-called taper angle) of the side surface of the partition wall 35 is not particularly limited, but is, for example, 60 ° to 90 °, preferably 75 ° to 85 °.

The pitch and height of the partition walls 35 are not particularly limited and can be set arbitrarily. For example, the pitch of the partition walls 35 is 30 μm to 300 μm, preferably 60 μm to 150 μm, and the height of the partition walls 35 is 10 μm to 100 μm, preferably 30 μm to 50 μm.

Further, it is preferable that the height of the partition wall 35 and the thickness of the porous layer 33 in the Z-axis direction are substantially uniform. This is because the distance between the pixel electrode 15 and the counter electrode 22 (so-called gap) is constant, and the electric field strength is made uniform. Thereby, nonuniformity such as response speed is improved.

The spacer 40 is for supporting the space between the driving substrate 10 and the counter substrate 20. The film thickness of the spacer 40 is, for example, 10 μm to 100 μm, and is preferably as thin as possible. Thereby, power consumption can be suppressed. The spacer 40 is made of an insulating material such as a polymer material, for example. The arrangement shape of the spacer 140 is not particularly limited, but it is preferable that the spacer 140 is provided so as not to disturb the movement of the migrating particles 32 and to uniformly distribute the migrating particles 32. The partition wall 35 may also serve as the spacer 40.

(1-2. Manufacturing method of display device)
The display device 1 of the present embodiment can be manufactured by the following method, for example. In addition, the manufacturing method demonstrated here is an example, You may manufacture using another method.

First, the TFT 12, the protective layer 13, the planarization insulating layer 14, and the pixel electrode 15 are formed in this order on one surface of the support base 11 to produce the drive substrate 10, and the partition unit 38 is formed via the adhesive layer 16. . In addition, as a formation method of each component, for example, an existing formation method can be selected and used as needed. Further, as described above, the partition unit 38 may be formed by resin molding using a thermal imprint method or the like to integrally form the partition 35 and the support 37, or may be formed separately. At this time, the spacer 40 may be formed at the same time.

Subsequently, the migrating particles 32 and the porous layer 33 are accommodated in the cell 36 formed by the partition unit 38 and the insulating liquid 31 is injected. When the porous layer 33 is formed, for example, a spinning solution is prepared by dispersing the forming material of the fibrous structure 331 in an organic solvent or the like, and the non-electrophoretic particles 332 are dispersed in the spinning solution. Spin by electrospinning method. Thereby, the porous layer 33B in which the non-migrating particles 332 are held by the fibrous structure 331 is formed. Subsequently, for example, spinning is performed by an electrostatic spinning method using a spinning solution in which a material for forming the fibrous structure 331 is dispersed in an organic solvent or the like. Thereby, the porous layer 33A composed of the fibrous structure 331 having optical transparency is formed. In addition, this spinning process may be performed in air | atmosphere and may be performed in a pressure-reduced atmosphere. In the porous layer 33 after formation, the area occupation ratio of the pores 333 is substantially uniform throughout.

Next, the drive substrate 10 and the counter substrate 20 provided with the counter electrode 22 and the adhesive layer 23 are arranged to face each other, and the drive substrate 10 and the counter substrate 20 are bonded together. Thereby, the display apparatus 1 (FIG. 1) shown in FIG. 1 is completed.

(1-3. Operation of display device)
The display device 1 operates as follows. 4A and 4B are for explaining the basic operation of the display device, and show a cross-sectional configuration corresponding to FIG. Here, in order to simplify the illustrated contents, the porous layer 33 is shown as one layer, and the adhesive layer 16 and the partition unit 38 are omitted. In addition, the migrating particles 32 are also shown as one type.

In the display device 1 in the initial state, the migrating particles 32 are arranged in the retreat area R1 (FIG. 4A). In this case, since the migrating particles 32 are concealed by the porous layer 33 in all the pixels, when the display device 1 is viewed from the counter substrate 20 side, no contrast is generated (an image is not displayed). It is in.

On the other hand, when a pixel is selected by the TFT 12 and an electric field is applied between the pixel electrode 15 and the counter electrode 22, as shown in FIG. 5B, the migrating particles 32 are moved from the retreat area R1 to the porous layer 33 for each pixel. It moves to the display area R2 via (pore 333). In this case, since the migrating particles 32 are concealed by the pixels hidden by the porous layer 33 and the pixels not hidden, the contrast is generated when the display device 1 is viewed from the counter substrate 20 side. Become. Thereby, an image is displayed.

The drive substrate 10 is provided with a peripheral circuit (not shown) for driving the electrophoretic element 30 for each pixel (applying a drive voltage between the pixel electrode 15 and the counter electrode 22). The peripheral circuit includes, for example, a voltage control driver for forming an active matrix driving circuit, a power source, a memory, and the like, and corresponds to an image signal for one or more selective sub-pixels. A drive voltage can be applied.

Display device 1 of this embodiment will be described in detail later, as electrophoretic particles 32, the average migration velocity of different electrophoretic particles 32C, 32M, due to the use of 32Y, the rear S ₂ side with respect to the display surface S ₁ side By changing the potential difference, the distribution positions of the migrating particles 32C, 32M, and 32Y can be adjusted. As a result, the display device 1 of the present embodiment can display five colors of white (W), cyan (C), magenta (M), yellow (Y), and black (K). Further, in the display device 1 of the present embodiment, full color display is also possible by subtractive color mixture.

(1-4. Action and effect)
In an electrophoretic display capable of color display, the use of colored particles having a difference in migration speed makes it easy to widen the difference between colored particles having a desired color and colored particles of other colors. The desired color can be displayed with a simple drive by concealing colored particles of other colors by non-migrating white particles with high light concealment arranged in the space from the (display surface) to the back electrode (back surface). It has become. However, in an electrophoretic display having such a configuration, it is difficult to keep the colored particles of a desired color in a position in contact with the display surface. Since the colored particles having a desired color away from the display surface are concealed by the non-migrating white particles, there is a problem that high saturation cannot be obtained and color reproducibility is lowered.

On the other hand, in the display device 1 of the present embodiment, as described above, the porous layer 33A having optical transparency is disposed on the display surface S ₁ side, and the optical reflection characteristic is provided on the back surface S ₂ side. The porous layer 33B was arranged. In addition, three types of migrating particles 32C, 32M, and 32Y having different optical reflection characteristics are used as the particles for migrating the insulating liquid 31. The migrating particles 32C, 32M, and 32Y are colored cyan (migrating particles 32C), magenta (migrating particles 32M), and yellow (migrating particles 32Y), for example. Further, the optical reflection characteristic of the porous layer 33B is different from the optical reflection characteristic of the migrating particles 32C, 32M, and 32Y, and is colored white by including the white non-migrating particles 332 here.

FIG. 5 shows changes over time in the potential difference with respect to the display surface S ₁ side on the back surface S ₂ side as an example of the driving method of the display device 1. Figure 6 is a representation of electrophoretic particles 32C by time variation of the potential difference across the display surface S ₁ side of the back S ₂ side shown in FIG. 5, 32M, the time variation of the average moving position of 32Y. The film thicknesses of the porous layer 33A and the porous layer 33B are designed by using the above calculation method, and the film thickness (W ₀ ) of the entire porous layer 33 is 30 μm, of which the porous layer 33A The film thickness (W ₁ ) is 10 μm, and the film thickness (W ₂ ) of the porous layer 33B is 20 μm. The film thickness (W ₀ ) of the porous layer 33 is the distance between the driving substrate 10 and the counter substrate 20. In addition, the thickness (W1) of each porous layer 33A, each electrophoretic particle 32C, 32M, 32Y is charged positive (+) and has the electrophoretic speed shown in Table 1.

First, all the electrophoretic particles 32C, 32M, move 32Y to the rear S ₂ side. At this time, the display surface S ₁ is displayed in white (starting point 0 second). When the potential on the back surface S ₂ side is increased, the positively charged migrating particles 32C, 32M, and 32Y start moving to the display surface S ₁ side. Most migration speed fast electrophoretic particles 32C of the potential difference at the time of reaching the display surface S ₁ by 0, slow electrophoretic particles 32M of electrophoretic speed than the electrophoretic particles 32C, 32Y are located in the porous layer 33B Therefore, the migrating particles 32M and 32Y are concealed by the porous layer 33B. As a result, the display color of the display surface S ₁ becomes cyan (C).

Subsequently, when the potential on the back surface S ₂ side is increased, the migrating particles 32M and 32Y staying between the display surface S ₁ and the back surface S ₂ move toward the display surface S ₁ . Electrophoretic particles 32M will reverse potential of back S ₂ side at the time of reaching the display surface S _1, when a low potential with respect to the display surface S _1, most migration speed fast electrophoretic particles 32C is faster than electrophoretic particles 32M to move to the back S ₂ side. When electrophoretic particles 32C to zero the potential difference at the time it reaches the rear S _2, electrophoretic particles 32C, 32M, 32Y are distributed from the display surface S ₁ side electrophoretic particles 32M, electrophoretic particles 32Y, in the order of electrophoretic particles 32C. At this time, since the migrating particles 32M are located in the light-transmitting porous layer 33A and the migrating particles 32Y and 32C are located in the porous layer 33B, the migrating particles 32Y and 32C are hidden by the porous layer 33B and displayed. The display color of the surface S ₁ is magenta (M). Incidentally, electrophoretic particles 32M is until most electrophoretic slow electrophoretic particles 32Y is concealed by a porous layer 32B, but would move toward the rear S _2, in the present embodiment, the display surface S _{Since the} light-transmitting porous layer 33A is disposed on the ₁ side, the saturation is ensured.

Then, all the electrophoretic particles 32C on the display surface S ₁ side to increase the potential of the back S ₂ side with respect to the display surface S ₁ side again, 32M, 32Y reaches the display surface S _1. At this time, the migrating particles 32C, 32M, and 32Y are subtractively mixed in the porous layer 33A on the display surface S ₁ side, and the display surface S ₁ is displayed in black. In the present embodiment, since the light-transmitting porous layer 33A is arranged on the display surface S ₁ side, subtractive color mixing is performed efficiently, and a display with high contrast can be obtained.

Subsequently, when the potential on the display surface S ₁ side is increased, all the migrating particles 32C, 32M, 32Y move toward the back surface S ₂ side. When electrophoretic particles 32M is zero potential difference at the time it reaches the rear S ₂ side, a state in which electrophoretic particles 32Y and electrophoretic particles 32C, the distance between 32M maintained. At this time the electrophoretic particles 32C, 32M is concealed in the porous layer 33B, electrophoretic particles 32Y is to located in the porous layer 33A, the display color of the display surface S ₁ becomes yellow (Y).

In this way, by changing the potential difference between the back surface S ₂ side and the display surface S ₁ side, multicolor display, here white (W), cyan (C), magenta (M), yellow (Y) and Black (K) five-color display is possible. Further, the halftone can be displayed by the same method. Furthermore, full color display is also possible by subtractive color mixing.

As described above, in the display device 1 according to the present embodiment, the three types of migrating particles 32C, 32M, and 32Y having different optical reflection characteristics are used as the migrating particles that migrate in the insulating liquid 31. . Further, the porous layer 33 is composed of a porous layer 33A having optical transparency and a porous layer 33B having optical reflection characteristics different from those of the migrating particles 32C, 32M, 32Y, and on the display surface S ₁ side. The porous layer 33A was arranged. Thus, electrophoretic particles 32C between the display surface S ₁ and the back S _2, 32M, when displaying the desired display color by controlling the distribution permutations of 32Y, electrophoretic particles having a desired display color (e.g., be distributed at a position electrophoretic particles 32M) is separated from the display surface S _1, electrophoretic particles 32M color saturation is concealed by a porous layer 33B it is possible to prevent the decrease. Therefore, it is possible to provide the display device 1 with high color reproducibility.

<2. Application example>
Next, an application example of the display device (display device 1) described in the above embodiment will be described. However, the configuration of the electronic device described below is merely an example, and the configuration can be changed as appropriate. The display device 1 can be applied to a part of various electronic devices or clothing, and the type of the electronic device is not particularly limited.

(Application example 1)
7A and 7B show the external configuration of the electronic book. The electronic book includes, for example, a display unit 110, a non-display unit 120, and an operation unit 130. Note that the operation unit 130 may be provided on the front surface of the non-display unit 120 as illustrated in FIG. 7A, or may be provided on the upper surface as illustrated in FIG. 7B. The display unit 110 is configured by the display device 1. The display device 1 may be mounted on a PDA (Personal Digital Assistants) having the same configuration as the electronic book shown in FIGS. 7A and 7B.

(Application example 2)
FIG. 8 shows the appearance of a tablet personal computer. The tablet personal computer has, for example, a touch panel unit 310 and a housing 320, and the touch panel unit 310 is configured by the display device 1.

(Application example 3)
The display device 1 can also be applied to a part of clothing such as a watch (watch), a bag, clothes, a hat, glasses, and shoes as a so-called wearable terminal. Below, an example of such an electronic device integrated with clothing is shown.

9A and 9B show the appearance of an electronic timepiece (wristwatch-integrated electronic device). The electronic timepiece has, for example, a dial (character information display portion) 410 and a band portion (color pattern display portion) 420, and the dial 410 and the band portion 420 include the display device 1. It is configured. For example, various characters and designs are displayed on the dial plate 410 as shown in FIGS. 9A and 9B by display driving using the above-described electrophoretic element. The band unit 420 is a part that can be attached to, for example, an arm. By using the display device 1 in the band unit 420, various color patterns can be displayed, and the design of the band unit 420 can be changed from the example of FIG. 9A to the example of FIG. 9B. . Electronic devices that are also useful in fashion applications can be realized.

As described above, the embodiment has been described with reference to the embodiment. However, the present disclosure is not limited to the aspect described in the embodiment, and various modifications can be made. For example, in the above embodiment, the fibrous structure 331 is preferably light transmissive (colorless and transparent). For example, the fibrous structure 331 constituting the porous layer 33B itself is an electrophoretic particle. 32 may be made of a light-reflective material that can be concealed.

In the above embodiment, the porous layer 33 has a two-layer structure of the porous layer 33A having light permeability and the porous layer 33B having optical reflection characteristics different from the migrating particles 32C, 32M, and 32Y. Is given as an example, but other layers may be included. For example, the porous layer 33B is composed of a plurality of layers may be arranged so that the average pore size of each pore 333 is sequentially reduced from the display surface S ₁ side. The reverse is also possible.

Furthermore, in the above-described embodiment, the electrophoretic element 30 including the insulating liquid 31, the electrophoretic particles 32C, 32M, and 32Y and the porous layer 33 is exemplified as the display element. It is not limited to the one using the porous layer 33 as long as it can form a contrast by light reflection for each pixel using the electrophoresis phenomenon. In the above-described embodiment, the example in which the migrating particles 32C, 32M, and 32Y that are colored cyan, magenta, and yellow are used as the migrating particles is not limited thereto. Alternatively, particles colored in a color such as white or black may be used.

In addition, the effect described in this specification is an illustration to the last, and is not limited, Moreover, there may exist another effect.

In addition, this indication can also take the following structures.
(1)
In insulating liquid,
Two or more types of migrating particles having selective optical transmission properties;
A first layer that is formed of a fibrous structure and has optical transparency, is disposed on the display surface side, and has a different optical reflection characteristic from the migrating particles, and is disposed on the back side. And a porous layer containing the display device.
(2)
Wherein for the porous layer having a thickness (W ₀₎ a first layer of a thickness (W _1), the thickness (W ₀₎ of the porous layer / a genus of the electrophoretic particles, wherein (1) The display device described in 1.
(3)
The display device according to (1) or (2), wherein the two or more types of electrophoretic particles have different electrophoretic velocities.
(4)
When three types of migrating particles having different migration speeds are used as the migrating particles,
Among the three types of electrophoretic particles, the electrophoretic speed of the electrophoretic particles moving fastest is V1, the electrophoretic speed of the electrophoretic particles moving fastest is V2, and the electrophoretic speed of the electrophoretic particles moving fastest is V3. Then
In larger numerical value of the thickness of the porous layer (W ₀₎ the thickness of the first layer to the (W _{1) is, W 0 × (V2 / V1} ) and W ₀ × (V3 / V2) The display device according to (1) or (3).
(5)
The display device according to any one of (1) to (4), wherein the two or more types of migrating particles have the same charge and different charge amounts.
(6)
The display device according to any one of (1) to (5), wherein the second layer includes non-electrophoretic particles having optical reflection characteristics different from the electrophoretic particles.
(7)
The display device according to any one of (1) to (6), wherein the first layer includes particles that do not reflect visible light.
(8)
The display device according to (7), wherein the particles that do not reflect visible light are titania (TiO ₂ ) having a particle size of 250 nm or less.
(9)
The two or more kinds of migrating particles have a color selected from one or more of cyan, magenta, yellow, green, blue, white and black, according to (1) to (8) above The display apparatus in any one of them.
(10)
The display device according to any one of (6) to (9), wherein the non-migrating particles are held by the fibrous structure.
(11)
A display device,
In the insulating liquid, the display device
Two or more types of migrating particles having selective optical transmission properties;
A first layer that is formed of a fibrous structure and has optical transparency, is disposed on the display surface side, and has a different optical reflection characteristic from the migrating particles, and is disposed on the back side. An electronic device having a porous layer containing:

This application claims priority on the basis of Japanese Patent Application No. 2016-040191 filed on March 2, 2016 at the Japan Patent Office. The entire contents of this application are hereby incorporated by reference. Incorporated into.

Those skilled in the art will envision various modifications, combinations, subcombinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. It is understood that

Claims (11)

1. In insulating liquid,
   Two or more types of migrating particles having selective optical transmission properties;
   A first layer that is formed of a fibrous structure and has optical transparency, is disposed on the display surface side, and has a different optical reflection characteristic from the migrating particles, and is disposed on the back side. And a porous layer containing the display device.
2. Wherein for the porous layer having a thickness (W ₀₎ a first layer of a thickness (W _1), the thickness (W ₀₎ of the porous layer / a genus of the electrophoretic particles, in claim 1 The display device described.
3. The display device according to claim 1, wherein the two or more types of migrating particles have different migration velocities.
4. When three types of migrating particles having different migration speeds are used as the migrating particles,
   Among the three types of migrating particles, the migration speed of the electrophoretic particles moving fastest is V1, the migration speed of the electrophoretic particles moving fastest is V2, and the migration speed of the electrophoretic particles moving fastest is V3. Then
   In larger numerical value of the thickness of the porous layer (W ₀₎ the thickness of the first layer to the (W _{1) is, W 0 × (V2 / V1} ) and W ₀ × (V3 / V2) The display device according to claim 1.
5. The display device according to claim 1, wherein the two or more types of migrating particles have the same charge and different charge amounts.
6. The display device according to claim 1, wherein the second layer includes non-electrophoretic particles having optical reflection characteristics different from those of the electrophoretic particles.
7. The display device according to claim 1, wherein the first layer includes particles that do not reflect visible light.
8. The display device according to claim 7, wherein the particles that do not reflect visible light are titania (TiO ₂ ) having a particle size of 250 nm or less.
9. The display device according to claim 1, wherein the two or more types of migrating particles have a color selected from one or more of cyan, magenta, yellow, green, blue, white and black.
10. The display device according to claim 6, wherein the non-electrophoretic particles are held by the fibrous structure.
11. A display device,
    In the insulating liquid, the display device
    Two or more types of migrating particles having selective optical transmission properties;
    A first layer that is formed of a fibrous structure and has optical transparency, is disposed on the display surface side, and has a different optical reflection characteristic from the migrating particles, and is disposed on the back side. An electronic device having a porous layer containing:

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