WO2017073169A1 - Electrophoresis element, display device, and electronic equipment - Google Patents

Abstract

Provided is electrophoresis element with which memory effect can be improved while suppressing reductions in reactivity. This electrophoresis element has, in an insulating liquid, electrophoresis particles and a porous layer that has optical reactivity different from the electrophoresis particles and includes a plurality of holes through which the electrophoresis particles pass. The average hole diameter in the porous layer is 1.0 - 4.3 times the average diameter of the electrophoresis particles.

Description

Electrophoretic element, display device and electronic device

The present disclosure relates to an electrophoretic element, a display device using the same, and an electronic apparatus.

In recent years, with the widespread use of mobile devices such as mobile phones or personal digital assistants, there is an increasing demand for display devices with low power consumption and high image quality. In addition, with the widespread use of electronic books, display devices with display quality suitable for reading applications are desired.

Examples of such a display device include various displays such as a cholesteric liquid crystal type, an electrophoretic type, an electrooxidation reduction type, and a twist ball type. Among them, a reflection type display device is advantageous. This is because a reflective display device performs display using reflection (scattering) of external light, as with paper, so that a display quality closer to that of paper can be obtained.

For example, Patent Documents 1 to 4 propose a reflection type display device using an electrophoretic phenomenon. Among these, in the display device described in Patent Document 1, an electrophoretic element in which electrophoretic particles are dispersed and a porous layer is disposed in an insulating liquid is provided with a charged layer having a polarity opposite to that of the electrophoretic particles. Thus, the memory property (non-volatility) can be improved. In Patent Documents 2 and 3, memory performance can be improved by adding a polymer to the migrating particles to cause depletion and aggregation. Or in patent document 4, memory property can be improved by aggregating electrophoretic particles using silica.

JP 2012-173602 A US Patent Application Publication No. 2002/0180687 Special table 2007-508588 JP 2011-43797 A

However, although the method of Patent Document 1 improves the memory performance, it takes time to peel off the migrating particles from the charged layer, which may reduce the responsiveness. In the methods of Patent Documents 2 and 3, the polymer that covers or is modified by the electrophoretic particles inhibits the movement of the electrophoretic particles, resulting in a slow response. Further, in the method of Patent Document 4, since the agglomerated migrating particles are difficult to peel off, the response is slow. As described above, there is a problem that the response is lowered while the memory performance is improved.

It is desirable to provide an electrophoretic element, a display device, and an electronic device that can improve memory performance while suppressing a decrease in responsiveness.

An electrophoretic element according to an embodiment of the present disclosure includes, in an insulating liquid, an electrophoretic particle, and a porous layer having a light reflectivity different from the electrophoretic particle and including a plurality of holes through which the electrophoretic particle passes. And the average pore diameter of the porous layer is 1.0 to 4.3 times the average particle diameter of the migrating particles.

A display device according to an embodiment of the present disclosure includes the electrophoretic element according to the embodiment of the present disclosure described above between a pair of electrodes.

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

In the electrophoretic element, the display device, and the electronic apparatus according to an embodiment of the present disclosure, the electrophoretic particles are loosened in the display state after one voltage is applied and the electrophoretic particles move to one side of the porous layer. And the apparent particle size of the migrating particles increases. Here, when the average pore size of the porous layer is 1.0 to 4.3 times the average particle size of the migrating particles, the apparent particle size of the migrating particles becomes larger than the pore size of the porous layer. The migrating particles are physically supported by the porous layer. In this display state, the migrating particles are only gently gathered, so when another voltage is applied, the migrating particles are easily separated and move through the insulating liquid and pass through the porous layer. be able to.

According to the electrophoretic element, the display device, and the electronic apparatus of the embodiment of the present disclosure, the average pore diameter of the porous layer is 1.0 to 4.3 times the average particle diameter of the electrophoretic particles. In the display state after voltage application, the apparent particle size of the migrating particles is larger than the pore size of the porous layer, and the migrating particles can be physically supported by the porous layer. Thereby, memory property improves. On the other hand, when other voltages are applied, the migrating particles are easily separated from each other, and thus mobility (responsiveness) is not easily inhibited. Therefore, it is possible to improve the memory performance while suppressing a decrease in responsiveness.

In addition, the effect described here is not necessarily limited, and may be any effect described in the present disclosure.

It is sectional drawing showing the structure of the display apparatus using the electrophoretic element which concerns on one embodiment of this indication. It is a plane schematic diagram for demonstrating the porous layer of the electrophoretic element shown in FIG. FIG. 2 is a cross-sectional view for explaining the operation of the display device shown in FIG. 1. 14 is a perspective view illustrating an appearance of application example 1. FIG. FIG. 4B is a perspective view illustrating another example of the electronic book illustrated in FIG. 4A. 12 is a perspective view illustrating an appearance of application example 2. FIG. 12 is a perspective view illustrating an appearance of application example 3. FIG. FIG. 6B is a perspective view illustrating another display example of the electronic timepiece illustrated in FIG. 6A.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (Example of display device having an electrophoretic element in which the ratio of the average pore diameter of the porous layer to the average particle diameter of the electrophoretic particles is within a predetermined range)
1-1. Configuration of electrophoretic element 1-2. Configuration of display device 1-3. Effect 2. Example 3. Application examples

<1. Embodiment>
(1-1. Configuration of electrophoretic element)
FIG. 1 illustrates a cross-sectional configuration of a display device (display device 1) including an electrophoretic element (electrophoretic element 30) according to an embodiment of the present disclosure. The electrophoretic element 30 generates contrast using an electrophoretic phenomenon, and is used as a display body of various electronic devices such as tablets. The electrophoretic element 30 includes electrophoretic particles 32 and a porous layer 33 having pores H in an insulating liquid 31. FIG. 1 schematically illustrates the configuration of the display device 1 including the electrophoretic element 30 and may differ from actual dimensions and shapes.

The insulating liquid 31 is made of, for example, an organic solvent such as paraffin or isoparaffin. As the insulating liquid 31, one kind of organic solvent may be used, or a plurality of kinds of organic solvents may be used. It is desirable to make the refractive index of the insulating liquid 31 as low as possible. 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. The kinematic viscosity of the insulating liquid 31, for example it is desirably 1.0 mm ² / sec or more 5.0 mm ² / sec or less, that for example is 1.0 mm ² / sec or more 3.0 mm ² / sec More desirable. This is because responsiveness and reflectance can be increased.

For example, a coloring agent, a charge adjusting agent, a dispersion stabilizer, a viscosity adjusting agent, a surfactant, or a resin may be added to the insulating liquid 31.

The migrating particles 32 dispersed in the insulating liquid 31 are one or more charged particles, and each is positively or negatively charged. The migrating particles 32 have arbitrary optical characteristics (light reflectivity, light reflectivity), and a contrast (CR) is generated due to the difference between the light reflectivity of the migrating particles 32 and the light reflectivity of the porous layer 33. It is like that. For example, the migrating particles 32 may be brightly displayed and the porous layer 33 may be darkly displayed, or the migrating particles 32 may be darkly displayed and the porous layer 33 may be brightly displayed.

When the migrating particles 32 are brightly displayed, the migrating particles 32 are visually recognized as, for example, white or a color close to white, and when darkly displayed, they are visually recognized as, for example, black or a color close to black. The color of the migrating particles 32 is not particularly limited as long as it produces a contrast with respect to the porous layer 33.

The migrating particles 32 are made of particles (powder) such as organic pigments, inorganic pigments, dyes, carbon materials, metal materials, metal oxides, glass, or polymer materials (resins). One of these may be used for the migrating particles 32, or two or more of them may be used. The migrating particles 32 may be composed of pulverized particles or capsule particles of resin solids containing the 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 dyes. The particle size of the migrating particles 32 is, for example, 30 nm or more and 300 nm or less. The particle size of the migrating particles 32 is a so-called primary particle size (minimum unit of particle size). In the present embodiment, the average particle diameter of the migrating particles 32 is configured to have a predetermined ratio with the average pore diameter of the porous layer 33 described later. However, the average particle diameter of the migrating particles 32 is measured in a solution in which the migrating particles 32 are dispersed (electrophoretic particle dispersion).

Examples of the organic pigments include azo pigments, metal complex azo pigments, polycondensed azo pigments, flavanthrone pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, and perylene pigments. Perinone pigments, anthrapyridine pigments, pyranthrone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments or indanthrene pigments. Inorganic pigments include, for example, zinc white, antimony white, iron black, titanium boride, bengara, mapico yellow, red lead, cadmium yellow, zinc sulfide, lithopone, barium sulfide, cadmium selenide, calcium carbonate, barium sulfate, lead chromate Lead sulfate, barium carbonate, lead white or alumina white. Examples of the dye include nigrosine dyes, azo dyes, phthalocyanine dyes, quinophthalone dyes, anthraquinone dyes, and methine dyes. The carbon material is, for example, carbon black. The metal material is, for example, gold, silver or copper. Examples of metal oxides include titanium oxide, zinc oxide, zirconium oxide, barium titanate, potassium titanate, copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, and copper-chromium-manganese oxide. Or copper-iron-chromium oxide. The polymer material is, for example, a polymer compound in which a functional group having a light absorption region in the visible light region is introduced. If it is a high molecular compound which has a light absorption area | region in visible region, the kind will not be specifically limited.

The specific material of the migrating particles 32 is selected according to, for example, the role that the migrating particles 32 play in causing contrast. When the migrating particles 32 display brightly, for example, a metal oxide such as titanium oxide, zinc oxide, zirconium oxide, barium titanate or potassium titanate is used for the migrating particles 32. When the migrating particles 32 display in the dark, the migrating particles 32 may be, for example, a carbon material such as carbon black or copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, copper-chromium-manganese oxide. In addition, metal oxides such as copper-iron-chromium oxide are used. Among these, it is desirable to use a carbon material for the migrating particles 32. Electrophoretic particles 32 made of a carbon material exhibit excellent chemical stability, mobility and light absorption.

The content (concentration) of the migrating particles 32 in the insulating liquid 31 is not particularly limited, and is, for example, 0.1 wt% to 10 wt%. In this concentration range, the shielding and mobility of the migrating particles 32 are ensured. Specifically, if the content of the migrating particles 32 is less than 0.1% by weight, the migrating particles 32 are less likely to shield (conceal) the porous layer 33, and there is a possibility that sufficient contrast cannot be generated. is there. 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.

It is desirable that the migrating particles 32 are easily dispersed and charged in the insulating liquid 31 for a long period of time and are difficult to be adsorbed on the porous layer 33. For this reason, for example, a dispersant is added to the insulating liquid 31. A dispersant and a charge control agent may be used in combination.

This dispersing agent or charge adjusting agent has, for example, a positive or negative charge, or both, and increases the amount of charge in the insulating liquid 31 and causes the migrating particles 32 to move by electrostatic repulsion. It is for dispersing. Examples of such a dispersant include Solsperce series manufactured by Lubrizol, BYK series or Anti-Terra series manufactured by BYK-Chemical, or Span series manufactured by TCI America.

In order to improve the dispersibility of the migrating particles 32, the migrating particles 32 may be subjected to a surface treatment. This surface treatment is, for example, rosin treatment, surfactant treatment, pigment derivative treatment, coupling agent treatment, graft polymerization treatment or microencapsulation treatment. In particular, long-term dispersion stability of the migrating particles 32 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 and a polymerizable functional group that can be adsorbed on the surface of the migrating particle 32 is used. The adsorbable functional group is determined according to the forming material of the migrating particle 32. For example, when the migrating particles 32 are made of a carbon material such as carbon black, an aniline derivative such as 4-vinylaniline, and when the migrating particles 32 are made of a metal oxide, methacrylic acid 3- Organosilane derivatives such as (trimethoxysilyl) propyl can be adsorbed respectively. Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group.

A surface treatment may be performed by introducing a polymerizable functional group onto the surface of the migrating particle 32 and grafting it onto the surface (graftable material). The graft material has, for example, a polymerizable functional group and a dispersing functional group. The functional group for dispersion disperses the migrating particles 32 in the insulating liquid 31 and retains dispersibility due to 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 capable of being adsorbed on the surface of the migrating particle 32 and an alkyl chain for imparting dispersibility can be used. Examples of such materials include titanate coupling agents (for example, KR-TTS manufactured by Ajinomoto Fine Techno Co., Ltd.) and aluminate coupling agents.

For details of the method for dispersing the migrating particles 32 in the insulating liquid 31, see “Dispersion Technology of Ultrafine Particles and its Evaluation: Surface Treatment / Fine Grinding and Dispersion Stabilization in Air / Liquid / Polymer— Science & Technology)).

The porous layer 33 has light reflectivity different from that of the migrating particles 32 and has a plurality of pores H (holes) through which the migrating particles 32 pass.

FIG. 2 shows an example of the porous layer 33. Thus, the porous layer 33 is configured to include, for example, a fibrous structure 34 having a plurality of pores H and non-migrating particles 35 held by the fibrous structure 34. The non-migrating particles 35 are held on the fibrous structure 34 by, for example, a surfactant.

Desirably, the fibrous structure 34 is a three-dimensional structure (irregular network structure such as a nonwoven fabric). This is because light (external light) is diffusely reflected (multiple scattering) and the reflectance of the porous layer 33 can be increased. Further, even when the thickness of the porous layer 33 is small, a high reflectance can be obtained, the contrast of the electrophoretic element 30 can be improved, and the energy required for the migration of the migrating particles 32 can be reduced.

The fibrous structure 34 is formed by, for example, one or a plurality of fibers (fibrous substances) folded randomly or one or a plurality of fibers entangled randomly. The fibers constituting the fibrous structure 34 have a sufficient length with respect to the fiber diameter (diameter). Moreover, what kind of thing may be sufficient as the shape of each fiber. For example, it may extend linearly or may have a curved shape. Moreover, it may be curled, may be bent in the middle, or may be branched. The pore H is a portion corresponding to the gap between such fibers.

The pore H penetrates the porous layer 33 and has a pore diameter (diameter) through which the migrating particles 32 can pass. The average pore diameter of the pores H (the average pore diameter of the porous layer 33) is 1.0 to 4.3 times the average particle diameter of the migrating particles 32. The average pore diameter of the porous layer 33 is preferably, for example, 150 nm or more and 750 nm or less. This is because the memory performance can be improved. In FIG. 1, the pores H pass straight through the porous layer 33 and have a constant diameter, but the shape of the pores H is not limited to such a shape. The pores H only need to penetrate the porous layer 33, and may be formed along, for example, an oblique direction or may meander. In addition, in one pore H, the pore diameter is not necessarily constant, and in fact, many pores are thicker or thinner. In this specification, the pore diameter of the pore H is the diameter of the narrowest part (minimum diameter).

In the fibrous structure 34, the fiber diameter is not constant, and a thick portion 34a and a thin portion 34b are mixed (FIG. 2). For example, a part having a diameter of 600 nm to 1200 nm and a part having a diameter of 200 nm to 500 nm are mixed. Desirably, the fibrous structure 34 includes a portion having a fiber diameter of twice or more the average fiber diameter at a ratio of 20% or less. More desirably, a portion having a fiber diameter that is twice or more the average fiber diameter is contained at a ratio of 10% or less, more desirably 5% or less. Here, an example is given in which the fibers are partially thick or thin, but one whole fiber may be thick with a constant width or thin with a constant width. Further, as the average fiber diameter becomes smaller, the light is more easily diffusely reflected, and the pore diameter of the pores H becomes larger.

The fiber diameter of the fibrous structure 34 can be adjusted by several methods. That is, in the step of forming the porous layer 33, for example, the polymer concentration, the mixing ratio of the non-migrating particles 35, the modification amount of the surfactant that modifies the surface of the non-migrating particles 35, or the surfactant added to the polymer solution The fiber diameter can be changed by adjusting the amount or the like. In the example shown in FIG. 2, the fiber diameter is relative to the portion (34b) in which the non-migrating particles 35 are discretely arranged with respect to the fibrous structure 34 (the dispersibility of the non-migrating particles 35 is good). The portion (34a) where the non-electrophoretic particles 35 are locally gathered and arranged is formed to have a relatively large fiber diameter.

The fiber diameter of the fibrous structure 34 can be measured, for example, as follows. That is, the display device 1 is cut using an instrument such as a microtome, and an arbitrary cross section or an arbitrary plane of the cut electrophoretic element 30 is observed using a scanning electron microscope (SEM). To measure. Specifically, the fiber diameter is measured at several tens to several hundreds (points) of the SEM image, and the average value of these is taken as the average fiber diameter of the fibrous structure 34. Furthermore, the ratio of the measurement point which shows the magnitude | size of 2 times or more of an average fiber diameter among all these measurement points is calculated.

The thickness of the porous layer 33 is, for example, 5 μm or more and 100 μm or less, depending on the element configuration of the electrophoretic element 30. In order to provide sufficient white reflectance, black reflectance, and response time, it is more desirably 15 μm or more and 50 μm or less.

The fibrous structure 34 as described above is, 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. It is formed by law. By using such a method, the fibrous structure 34 having a sufficient length with respect to the fiber diameter can be easily and stably formed.

The fibrous structure 34 can be composed of nanofibers. Here, the nanofiber is a fibrous substance having a fiber diameter of 1 nm to 1000 nm and a length of 100 times or more of the fiber diameter. By using such nanofibers as the fibrous structure 34, light is easily diffusely 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 34 made of nanofibers, the proportion of the pores H in the unit volume increases, and the migrating particles 32 can easily pass through the porous layer 33. Therefore, the energy required for moving the migrating particles 32 can be reduced. The fibrous structure 34 made of nanofibers is preferably formed by an electrostatic spinning method. By using the electrospinning method, the fibrous structure 34 having a small fiber diameter can be easily and stably formed.

It is desirable to use a fibrous structure 34 having a light reflectance different from that of the migrating particles 32. Thereby, a contrast due to a difference in light reflectance between the porous layer 33 and the migrating particles 32 is easily formed. A fibrous structure 34 showing light transparency (colorless and transparent) in the insulating liquid 31 may be used.

Non-electrophoretic particles 35 are one or more particles that are fixed to the fibrous structure 34 and do not undergo electrophoresis. The non-migrating particles 35 may be embedded in the fibrous structure 34 or may partially protrude from the fibrous structure 34. The average particle diameter of the non-migrating particles 35 is, for example, not less than 150 nm and not more than 700 nm.

The light reflectance of the non-migrating particles 35 is different from the light reflectance of the migrating particles 32. The non-migrating particles 35 can be made of the same material as the material of the migrating particles 32 described above. Specifically, when the non-migrating particles 35 (porous layer 33) display brightly, the same material as that when the migrating particles 32 display brightly can be used. When the non-electrophoretic particles 35 display dark, the same material as that used when the electrophoretic particles 32 display dark can be used. When performing a bright display by the porous layer 33, it is desirable that the non-migrating particles 35 be made of a metal oxide. Thereby, it is possible to obtain excellent chemical stability, fixability and light reflectivity. The constituent materials of the non-migrating particles 35 and the migrating particles 32 may be the same or different. The color visually recognized when the non-electrophoretic particle 35 performs bright display or dark display is the same as that described for the electrophoretic particle 32.

Further, the surface of the non-electrophoretic particle 35 may be modified with a surfactant. Surfactants are, for example, anionic (anionic) surfactants having a carboxylic acid, sulfonic acid or phosphoric acid structure as hydrophilic groups and cationic (cationic) properties having, for example, tetraalkylammonium or alkylamine as hydrophilic groups. Surfactant is mentioned. In addition, nonionic (nonionic) surfactants having a hydrophilic part as a non-electrolyte, that is, a non-ionized hydrophilic part, and amphoteric surfactants having both an anionic part and a cationic part in the molecule may be used. . Examples of amphoteric surfactants include alkyl dimethylamine oxide and alkyl carboxybetaine. In the case where a metal material such as titanium oxide is used as the non-electrophoretic particle 35, it is desirable to use an anionic surfactant. In particular, a surfactant having a hydrophilic group with a small molecular volume such as carboxylic acid is desirable because it easily covers the entire surface of the non-electrophoretic particle 35. Further, it is desirable that the surfactant does not ooze into the insulating liquid 31 so that the display characteristics are not deteriorated for a long time.

Such a porous layer 33 can be formed by the following method, for example. First, as the non-migrating particles 35, for example, titanium oxide having a predetermined primary particle size is prepared, and this is added to, for example, an organic solvent in which a carboxylic acid anionic surfactant is dissolved and stirred. Thereby, titanium oxide (non-electrophoretic particles 35) whose surface is coated with a carboxylic acid anionic surfactant is obtained. Next, for example, a constituent material of the fibrous structure 34 such as a polymer material (polymer) is dissolved in an organic solvent to prepare a solution, and then the non-electrophoretic particles 35 are added to the solution and sufficiently stirred. And spinning to prepare a spinning solution. Subsequently, the fibrous structure 34 holding the non-migrating particles 35 is formed by spinning the spinning solution by, for example, an electrostatic spinning method. Here, the primary particle size is a minimum particle size. For example, when the particles are aggregated or bonded, the primary particle size represents the particle size of each particle.

Thus, the dispersibility of the non-migrating particles 35 in the spinning solution is enhanced by using the non-migrating particles 35 that have been modified with a surfactant in advance. As a result, an electric field is easily applied to the non-migrating particles 35 during spinning, and a fibrous structure 34 with a reduced fiber diameter, that is, a fine fiber is obtained. Note that the surface of the non-electrophoretic particle 35 fixed to the fibrous structure 34 is covered with a polymer constituting the fibrous structure 34.

The porous layer 33 is not limited to the one including the fibrous structure 34 and the non-electrophoretic particle 35 as described above, and may include the pore H and a light reflectivity different from that of the electrophoretic particle 32. That's fine. For example, it may be a polymer film having pores H formed by laser processing. Further, the porous layer 33 may be a cloth knitted with synthetic fibers or the like, or an open-cell porous polymer. When combining non-electrophoretic particles with such a polymer material, an operation of kneading the non-electrophoretic particles into the polymer may be performed.

Also, the fibrous structure 34 is preferably composed of molecules having a main skeleton (main part of the molecule) composed of, for example, carbon atoms, oxygen atoms and hydrogen atoms. In other words, the main skeleton of this molecule does not contain atoms other than carbon atoms, oxygen atoms, and hydrogen atoms, and consists only of these atoms. It is desirable that such molecules forming the fibrous structure 34 do not include a highly polar functional group such as a hydroxyl group and a carboxylic acid group. Thereby, the absolute value of the surface potential of the fibrous structure 34 becomes small, and the responsiveness of the electrophoretic element 30 can be improved. Here, the main skeleton refers to a portion excluding both ends of the molecule. The molecules forming the fibrous structure 34 are preferably composed of carbon atoms, oxygen atoms and hydrogen atoms up to both ends, but the terminals contain atoms other than these carbon atoms, oxygen atoms and hydrogen atoms. May be. For example, when a polymer is synthesized by radical polymerization, a polymerization initiator such as azobisisobutyronitrile (AIBN) is used as a catalyst. Nitrogen atoms and the like are contained at both ends of the polymer synthesized in this way, but the atoms at the ends are less than 1/1000 of the whole molecule in terms of molecular weight. Therefore, this terminal atom contributes little to the properties of the molecule. The same applies to polymerization initiators other than AIBN. Thus, the reactivity of the fibrous structure 34 composed of only carbon atoms, oxygen atoms, and hydrogen atoms is low, so that the fibrous structure 34 exists stably in the insulating liquid 31. Therefore, the electrophoretic element 30 can obtain high reliability.

The molecule forming the fibrous structure 34 is a chain polymer. Here, a chain molecule (chain molecule) refers to a molecule that does not include a cyclic atomic arrangement structure. Examples of the cyclic atomic arrangement include a monocyclic compound and a heterocyclic compound. Monocyclic compounds are composed of a single element, and specifically include aromatic compounds, cycloalkenes, cycloalkanes, cycloalkynes, and the like. The heterocyclic compound is composed of two or more kinds of elements, and specifically includes pyrrole, carbazole, cyclic acetal, pyran, furan and thiophene. The chain molecule may be linear or branched. When the fibrous structure 34 is composed of chain molecules, the steric hindrance is smaller than that of a molecule including a cyclic structure, so that the migrating particles 32 are easily moved, and the contrast and responsiveness of the electrophoretic element 30 are improved. To do.

The chain molecule constituting the fibrous structure 34 includes an ester group. For example, it is desirable to form the fibrous structure 34 with an acrylic resin. Specific examples of the chain molecule include polyalkyl methacrylate, polyalkyl acrylate, polyalkenyl methacrylate, polyalkenyl acrylate, polyalkynyl methacrylate and polyalkynyl acrylate. This chain molecule does not have a functional group having a polarity higher than that of the ester group, and the absolute value of the surface potential of the fibrous structure 34 is, for example, 20 mV or less. It is more desirable to select the chain molecule so that the absolute value of the surface potential of the fibrous structure 34 is 10 mV or less. That is, the ester group has a smaller polarity than the cyano group and the like, but this is sufficiently large for spinning using the electrospinning method, and the fibrous structure 34 can be easily formed by the electrospinning method. can do.

For the chain molecule constituting the fibrous structure 34, it is desirable to use a material that is not easily decomposed by microorganisms. That is, it is desirable that the chain molecule is resistant to biodegradation. Examples of the biodegradable polymer include polylactic acid, polyvinyl alcohol, cellulose acetate, collagen, gelatin, and chitosan. Since such a polymer is easily decomposed, there is a possibility that the characteristics of the fibrous structure cannot be maintained when some kind of stimulus is applied to the electrophoretic element from the outside. In addition, many of such polymers are water-soluble and may be dissolved by moisture in the electrophoretic element, so that the shape of the fibrous structure cannot be maintained. On the other hand, when the fibrous structure 34 is formed of chain molecules having resistance to biodegradation, the stability of the fibrous structure 34 is increased. Therefore, the reliability of the electrophoretic element 30 can be improved. The surface of the fibrous structure 34 may be covered with an arbitrary protective layer.

(1-2. Configuration of display device)
Next, the overall configuration and operation principle of the display device 1 will be described.

(overall structure)
1 and 3 illustrate a cross-sectional configuration of the display device 1 using the electrophoretic element 30. FIG. The display device 1 is an electrophoretic display (so-called electronic paper display) that displays an image (for example, character information or a symbol) using an electrophoretic phenomenon, and between the drive substrate 10 and the counter substrate 20, The electrophoretic element 30 described above is included. The space between the driving substrate 10 and the counter substrate 20 is adjusted to a predetermined distance by the spacer 40.

The drive substrate 10 has, for example, a TFT (Thin Film Transistor) 12 on one surface of the support member 11. A protective layer 13 and a planarization insulating layer 14 are formed on the TFT 12. A pixel electrode 15 is provided on the planarization insulating layer 14. An electrophoretic element 30 is formed on the pixel electrode 15 via an adhesive layer (not shown). The TFT 12 and the pixel electrode 15 are arranged in a matrix or segment, for example.

The support member 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. Ketone (PEEK) etc. are mentioned.

In the display device 1, since an image is displayed on the surface of the counter substrate 20, the support member 11 may be non-light transmissive. The support member 11 may be configured by a rigid substrate such as a wafer, or may be configured by a flexible thin glass or film. By using a flexible material for the support member 11, the 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. 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.

The counter substrate 20 includes, for example, a support member 21 and a counter electrode 22. The counter electrode 22 is provided on the entire surface of the support member 21 (the 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 member 21 is made of the same material as the support member 11 except that it is light transmissive. For the counter electrode 22, for example, indium oxide-tin oxide (ITO), antimony oxide-tin oxide (ATO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), or the like has a light-transmitting conductivity. A material (transparent conductive film) can be used.

When displaying an image on the counter substrate 20 side, since the electrophoretic element 30 is viewed through the counter electrode 22, it is desirable that the light transmittance (transmittance) of the counter electrode 22 is as high as possible. For example, it is 80% or more. The electrical resistance of the counter electrode 22 is desirably as low as possible, for example, 100Ω / □ or less.

In this display device 1, an insulating liquid 31 is filled between the drive substrate 10 and the counter substrate 20, specifically, a space between the pixel electrode 15 and the counter electrode 22. The porous layer 33 is supported by the spacer 40, for example. The space filled with the insulating liquid 31 between the pixel electrode 15 and the counter electrode 22 is, for example, a region close to the pixel electrode 15 with the porous layer 33 as a boundary, as a save region R1 and a counter electrode 22. The area on the near side is divided as a display area R2. In practice, however, the saving area R1 and the display area R2 are often not clearly separated. That is, the porous layer 33 is disposed in almost the entire area between the pixel electrode 15 and the counter electrode 22, and the retreat area R 1 and the display area R 2 exist in the porous layer 33. Alternatively, the porous layer 33 may be disposed so as to be biased to one of the pixel electrode 15 and the counter electrode 22. By applying an electric field to the electrophoretic element 30 through the pixel electrode 15 and the counter electrode 22, the migrating particles 32 move toward the pixel electrode 15 or the counter electrode 22 in accordance with the electric field.

The thickness of the spacer 40 is, for example, 10 μm or more and 100 μm or less. The spacer 40 is made of, for example, an insulating material such as a polymer material, and is provided, for example, in a lattice shape between the drive substrate 10 and the counter substrate 20. Although the arrangement shape of the spacer 40 is not particularly limited, it is desirable that the spacer 40 is provided so as not to disturb the movement of the migrating particles 32 and to be uniformly distributed.

(Operating principle)
In the display device 1, for example, as illustrated in FIG. 1, the migrating particles 32 are shielded by the porous layer 33 in the state where the migrating particles 32 are disposed in the retreat area R <b> 1 in all the pixels. When the electrophoretic element 30 is viewed from the 20 side, no contrast is generated (an image is not displayed).

On the other hand, when a pixel is selected by the TFT 12 and a voltage is applied between the pixel electrode 15 and the counter electrode 22, as shown in FIG. 3, in the selective pixel, the migrating particles 32 are porous from the retreat area R1. It moves to the display area R2 via the quality layer 33 (pore H). In this case, since the pixels where the migrating particles 32 are shielded by the porous layer 33 and the pixels which are not shielded coexist, when the electrophoretic element 30 is viewed from the counter substrate 20 side, the migrating particles 32 and the porous layer are seen. Contrast is generated due to the difference in light reflectivity from 33. Thereby, an image is displayed.

In addition, according to this display device 1, it is possible to display a high-quality image suitable for colorization and moving image display, for example, by the electrophoretic element 30 having high responsiveness.

Here, since the electrophoretic element 30 generates contrast due to the difference in light reflectivity between the electrophoretic particles 32 and the porous layer 33, the electrophoretic particles 32 and the porous layer 33 that are brightly displayed. The light reflectance is higher than the light reflectance for the dark display. For example, it is desirable that the light reflectance of the porous layer 33 (non-migrating particles 35) be higher than that of the migrating particles 32, so that the porous layer 33 is brightly displayed and the migrating particles 32 are darkly displayed. This is because the light reflectance at the time of bright display is increased by the irregular reflection of light in the porous layer 33, and the contrast is improved.

(1-3. Effect)
In the display device 1, when a single voltage is applied to the electrophoretic element 30, as described above, the electrophoretic particles 32 move to one side of the porous layer 33 in the selective pixel region, thereby improving the contrast. It is possible to display an image. In this display state, the migrating particles 32 gather together in the vicinity of the pixel electrode 15 or the counter electrode 22, and the apparent particle size of the migrating particles increases.

In the present embodiment, since the average pore diameter of the porous layer 33 is 1.0 to 4.3 times the average particle diameter of the migrating particles 32, the apparent particle diameter of the migrating particles 32 is the porous layer 33. The migrating particles 32 are physically supported by the porous layer 33. Thereby, even after the supply of voltage is temporarily stopped, the display state is maintained, that is, the memory performance is improved.

Here, as a method for improving the memory performance, for example, there is a method of providing a charged layer having a polarity opposite to that of the migrating particles. In this method, it takes time to peel off the migrating particles from the charged layer. In addition, there is a method of adding polymer to the electrophoretic particles to cause depletion and aggregation. However, in this method, the polymer covering the electrophoretic particles or modified with the electrophoretic particles inhibits the movement of the electrophoretic particles, so that the responsiveness is high. Become slow. In addition, there is a method of aggregating the migrating particles using silica, but the responsiveness is slow because the agglomerated migrating particles are difficult to peel off. As described above, the memory performance is improved while the responsiveness is lowered. Alternatively, extra energy is required to peel off the migrating particles, increasing power consumption.

On the other hand, in the present embodiment, the electrophoretic particles 32 are only gathered gently in the display state after application of a certain voltage. Therefore, when another voltage is applied again, the electrophoretic particles 32 are easily separated. Then, it can move through the insulating liquid 31 and pass through the porous layer 33. That is, it is difficult to inhibit mobility (responsiveness).

As described above, in the present embodiment, the average pore diameter of the porous layer 33 (pore H) is 1.0 to 4.3 times the average particle diameter of the migrating particles 32, so that the display after voltage application is performed. In this state, the apparent particle size of the migrating particles 32 is larger than the pore size of the porous layer 33, and the migrating particles 32 can be physically supported by the porous layer 33. Thereby, memory property improves. On the other hand, when other voltages are applied, the migrating particles are easily separated from each other, and thus mobility (responsiveness) is not easily inhibited. Therefore, it is possible to improve the memory performance while suppressing a decrease in responsiveness.

Further, when the fibrous structure 34 includes a portion having a fiber diameter twice or more the average fiber diameter at a ratio of 20% or less, the reflectance can be further increased. This can increase the contrast. By making the ratio 10% or less or 5% or less, the reflectance can be further increased.

Furthermore, since the kinematic viscosity of the insulating liquid 31 is 1.0 mm ² / second or more and 5.0 mm ² / second or less, preferably 1.0 mm ² / second or more and 3.0 mm ² / second or less, the responsiveness and The reflectance can be increased.

<2. Example>
Next, examples of the above embodiment will be described in detail.

Display devices (Experimental Examples 1 to 18) were prepared using black (dark display) migrating particles and a white (bright display) porous layer (particle-containing fibrous structure) according to the following procedure.

(Experimental example 1)
First, a mixed solution of 400 ml of tetrahydrofuran and 400 ml of methanol was prepared, and then 50 g of composite oxide fine particles (copper-iron-manganese oxide: Daipi Seika Kogyo Co., Ltd. Daipyroxide Side Color TM9550) were added to the solution. Ultrasonic stirring (at 25 ° C. to 35 ° C. for 30 minutes) was performed in an ultrasonic bath. Next, 40 ml of 28% ammonia water was added dropwise to the dispersion of the composite oxide fine particles over 30 minutes, and then a solution in which 10 g of preneact KR-TTS (manufactured by Ajinomoto Fine Techno Co., Ltd.) was dissolved in 80 ml of tetrahydrofuran was added over 30 minutes. And dripped. Subsequently, the ultrasonic bath was heated to 60 ° C. and held for 3 hours, and then cooled to room temperature, followed by centrifugation and decantation. Subsequently, the precipitate after decantation was redispersed in a mixed solvent of tetrahydrofuran and methanol (volume ratio 1: 1), followed by centrifugation (at 6000 rpm for 10 minutes) and decantation. The precipitate obtained by repeating this washing operation three times was dried overnight in a vacuum oven at 70 ° C. As a result, black electrophoretic particles coated with a dispersing group that are negatively charged in the insulating liquid were obtained.

After preparing the migrating particles, 6 g of long-chain alkyl succinic anhydride as a dispersant was dissolved in 94 g of the insulating liquid to prepare a solution D1. As the insulating liquid, isoparaffin (isopar G manufactured by ExxonMobil) was used. To this solution D1 (9 g), 1 g of the above migrating particles was added, and ultrasonic dispersion was performed. Subsequently, centrifugation and decantation were performed, followed by redispersion in the insulating liquid. This operation was repeated three times, and an insulating liquid was added so that the electrophoretic particle component in the obtained dispersion was 10% by weight to prepare a solution D2. Subsequently, 49.6 g of the insulating liquid, 0.25 g of the basic additive alkylamine, and 0.12 g of the acidic additive are added to the solution D2 (50 g) and stirred, and the migrating particles and the acidic additive are added. Insulating liquids (electrophoretic particle dispersions) each containing 0.4 mmol and 1.75 mmol of basic additive were obtained. At this time, as shown in Table 1 below, five types of electrophoretic particle dispersions (electrophoretic particle dispersions 1 to 5) having different average particle diameters were prepared as shown in Table 1 below. The average particle size of the migrating particles can be measured in the prepared dispersion by, for example, a laser Doppler method.

On the other hand, the porous layer was formed as follows. First, titanium oxide having an average primary particle diameter of 250 nm was prepared as non-electrophoretic particles, mixed with 15% by weight in tetrahydrofuran in which a carboxylic acid anionic surfactant was dissolved, and stirred for 1 hour using a paint shaker. Thereafter, the mixture was centrifuged (5000 rpm for 10 minutes), the solvent was removed by decantation, washed 3 times, and dried overnight at 70 ° C. Thereby, titanium oxide coated with a carboxylic acid anionic surfactant (referred to as non-electrophoretic particles T1) was obtained.

Next, polymethyl methacrylate was prepared as a constituent material of the fibrous structure. After 13 g of this polymethyl methacrylate was dissolved in 87 g of N, N′-dimethylformamide, 30 g of non-electrophoretic particles T1 were added to 70 g of this solution and mixed with a bead mill. As a result, a spinning solution for forming the fibrous structure was obtained. A pixel electrode made of ITO having a predetermined pattern was formed on the driving substrate, and then spinning was performed using this spinning solution. Specifically, the spinning solution was put into a syringe, and spinning was performed on a driving substrate. As a result, as shown in Table 2 below, three types of fibrous structures (A1 to A3) having the same average fiber diameter (520 nm) and different weights per unit area (spinning amount) were formed. The weight of the fibrous structure A1 was the largest, and the weight was decreased in the order of the fibrous structures A2 and A3. Spinning was performed using an electrospinning apparatus (NANON manufactured by MEC Co., Ltd.).

Further, the amount of the carboxylic acid anionic surfactant is increased as compared with the fibrous structures A1 to A3, and the other conditions are the same as those of the fibrous structures A1 to A3. Body (A4 to A6) was prepared. In these fibrous structures A4 to A6, at least two kinds of fibers having different fiber diameters are mixed. Here, if a fiber having a fiber diameter twice or more of the average fiber diameter is a fiber L and the other fiber is a fiber S, the non-migrating particles T1 are hardly dispersed in the fiber L. For this reason, it is desirable that the number (ratio) of the fibers L is smaller than the number (ratio) of the fibers S. As shown in Table 2, the fibrous structure A4 has a fiber L ratio of 5%, the fibrous structure A5 has a fiber L ratio of 10%, and the fibrous structure A6 has a fiber L ratio of 10%. The ratio was 20%.

The average pore diameters of the fibrous structures A1 to A6 were measured in a state of being crushed to 15 μm so as to be the same as the cell gap in the final display device. As a measuring device, a palm porometer manufactured by PMI was used. In the fibrous structures A1 to A3, the average pore diameter varies depending on the weight. Specifically, the larger the weight, the smaller the average pore diameter, and the smaller the weight, the larger the average pore diameter. This is because the volume fraction of the fibrous structures A1 to A3 varies because the cell gap is the same (15 μm).

The average fiber diameter and the ratio of the fibers L of the fibrous structures A1 to A6 were measured by observation with an SEM. In the fibrous structures A4 to A6, the average fiber diameter is smaller than that of the fibrous structures A1 to A3, but the ratio of the fibers L is large. Therefore, the average pore diameter of the fibrous structures A4 to A6 is approximately the same as that of the fibrous structure A1.

As described above, after the porous layer was formed on the drive substrate, the unnecessary porous layer was removed from the drive substrate. Specifically, a spacer having a thickness of 15 μm was disposed inside the fibrous structure, and unnecessary portions of the porous layer were removed. On the other hand, a counter electrode made of ITO is formed on the support member as a counter substrate, and an insulating liquid in which the electrophoretic particles are dispersed (electrophoretic particle dispersions 1 to 5) is injected onto the counter substrate. The driving substrate on which the porous layer was formed was placed in an overlapping manner. At this time, the pixel electrode and the counter electrode were separated so as to hold the porous layer with the spacer. Finally, the peripheral portion is sealed with, for example, an ultraviolet curable resin so that the electrophoretic particle dispersion does not leak, and the display device 1 is completed by irradiating with ultraviolet rays to seal between the driving substrate and the counter substrate. .

By combining each of the electrophoretic particle dispersions 1 to 5 and the fibrous structures A1 to A6, the ratio of the average pore diameter of the porous layer to the average particle diameter of the electrophoretic particles was changed, and a total of 18 patterns (experimental examples) The display device 1 of 1 to 18) was produced, and each memory property and reflectance were evaluated. The results are shown in Table 3. The “ratio” in Table 3 is a value of (average pore diameter of fibrous structure) / (average particle diameter of migrating particles). In the reflectance (white reflectance), 43% or more is indicated as “aa”, 40% or more as “a”, and less than 40% as “b”. In the memory property, the white retention rate after 10 minutes is indicated as “a” when 90% or more and “b” when less than 90%.

As in Experimental Examples 1, 2, 3, 6, 9, and 12, when the “ratio” is large, that is, when the average particle diameter is small with respect to the average pore diameter, it becomes difficult to support the migrating particles by the fibrous structure. Memory performance is not good. For this reason, it is desirable that the value of “ratio” is 1.0 or more and 4.3 or less. On the other hand, when the “ratio” is small as in Experimental Examples 13, 14, and 15, that is, when the average particle size is large with respect to the average pore size, it becomes easy to support the migrating particles by the fibrous structure, but in the first place the fibrous shape It becomes difficult to pass through the structure. For this reason, a reflectance will fall. Therefore, the value of “ratio” is more preferably 3.3 or more and 4.3 or less.

Experimental Examples 16, 17, and 18 use fibrous structures A4 to A6 containing fibers L. Although the fibrous structures A4 to A6 have a smaller average fiber diameter than the fibrous structures A1 to A3, the fibrous structures A4 to A6 have the same average pore diameter because they contain the fibers L. When the amount of the surfactant is increased, the average fiber diameter is reduced from the fibrous structure A4 to the fibrous structure A5. However, when the amount is excessively increased, the balance is lost as in the fibrous structure A6. The fiber L increases and the average fiber diameter increases. In Experimental Examples 16 to 18, the electrophoretic particle dispersion liquid 2 having an average particle diameter of 150 nm is combined with these fibrous structures A4 to A6. In Experimental Examples 4 and 5, the electrophoretic particle dispersion liquid 2 having an average particle diameter of 150 nm is combined with the fibrous structures A1 and A2 that do not include the fiber L. When these experimental examples 16 to 18 are compared with experimental examples 4 and 5, it can be seen that the inclusion of the fiber L improves the reflectance. This is because the path through which the migrating particles can pass can be ensured at the same time by mixing the fibers L while increasing the dispersibility of the white pigment (non-migrating particles) by reducing the diameter of the fibers. The number of fibers L is preferably 20% or less and more preferably 10% or less because the reflectance starts to decrease by increasing from 10% to 20% when comparing Experimental Examples 17 and 18. desirable.

From the above results, the electrophoretic element can exhibit memory properties regardless of the viscosity of the solution. That is, the memory property based on the kinematic viscosity of the insulating liquid used as a solvent can be improved. Here, using a solvent having different kinematic viscosities (solvents B1 to B5), a display device was produced under the same conditions as in Experimental Example 4, and the reflectance and memory performance of each display device were evaluated. Table 4 shows.

When the solvent B1 having a low kinematic viscosity is used, it is difficult to handle because the boiling point is low, and the display device cannot be stably produced. However, when the solvents B2 to B5 having a high kinematic viscosity are used, the display device is stabilized. It was possible to make it.

When compared with the solvents B2 to B4 having a low kinematic viscosity, the initial white reflectance was lowered when the solvent B5 was used. The reflectance retention ratio (memory property) after 10 minutes was almost the same regardless of the kinematic viscosity. This indicates that the memory performance appears regardless of the viscosity of the solution of the electrophoretic element. However, if the kinematic viscosity is increased up to the solvent B5, the responsiveness becomes slow and the reflectance decreases.

From these facts, the kinematic viscosity of the solvent is desirably 1.0 mm ² / sec or more and 5.0 mm ² / sec or less, and more desirably 1.0 mm ² / sec or more and 3.0 mm ² / sec or less. In other words, the boiling point of the solvent is desirably 140 ° or more and 280 ° or less, and more desirably 140 ° or more and 240 ° or less. Thereby, it is possible to improve reflectivity or responsiveness while improving memory performance.

<3. Application example>
Next, an application example of the display device 1 will be described.

The display device 1 of the present disclosure can be applied to various electronic devices or clothing, and the type of the electronic device is not particularly limited. The display device 1 can be mounted on, for example, the following electronic devices. However, the configuration of the electronic device or the like described below is merely an example, and the configuration can be changed as appropriate.

(Application example 1)
4A and 4B 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 shown in FIG. 4A or may be provided on the upper surface as shown in FIG. 4B. The display unit 110 includes 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. 4A and 4B.

(Application example 2)
FIG. 5 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 includes the display device 1.

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

(Application example 3)
6A and 6B show the appearance of an electronic timepiece (a 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. 6A and 6B by display driving using the electrophoretic element 30 described above. The band unit 420 is a part that can be attached to an arm or the like, for example. Various display patterns can be displayed by using the display device 1 in the band unit 420, and the design of the band unit 420 can be changed from the example of FIG. 6A to the example of FIG. 6B. . Electronic devices that are also useful in fashion applications can be realized.

Although the present disclosure has been described with reference to the embodiment and examples, the present disclosure is not limited to the above-described embodiment and the like, and various modifications are possible.

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

The present disclosure can also have the following configurations.
(1)
In insulating liquid,
Electrophoretic particles,
And having a light reflectivity different from that of the migrating particles, and a porous layer including a plurality of holes through which the migrating particles pass,
The electrophoretic element, wherein the porous layer has an average pore size of 1.0 to 4.3 times the average particle size of the electrophoretic particles.
(2)
The average pore size of the porous layer is not less than 3.3 times and not more than 4.3 times the average particle size of the electrophoretic particles. The electrophoretic element according to (1) above.
(3)
The average pore diameter of the porous layer is 150 nm or more and 750 nm or less. The electrophoretic device according to (1) or (2).
(4)
The porous layer includes a fibrous structure that forms the plurality of pores;
The electrophoretic element according to any one of (1) to (3), wherein the fibrous structure includes a portion having a fiber diameter that is twice or more the average fiber diameter at a ratio of 20% or less.
(5)
The porous layer includes a fibrous structure that forms the plurality of pores;
The electrophoretic element according to any one of (1) to (4), wherein the fibrous structure includes a portion having a fiber diameter that is twice or more the average fiber diameter at a ratio of 10% or less.
(6)
The porous layer includes a fibrous structure that forms the plurality of pores;
The electrophoretic element according to any one of (1) to (5), wherein the fibrous structure includes a portion having a fiber diameter of twice or more the average fiber diameter at a ratio of 5% or less.
(7)
The porous layer includes a fibrous structure that forms the plurality of pores;
The fibrous structure includes a part having a fiber diameter of 600 nm or more and 1200 nm or less and a part having a fiber diameter of 200 nm or more and 500 nm or less, in any one of the above (1) to (6) Electrophoretic element.
(8)
The electrophoretic device according to any one of (1) to (7), wherein the insulating liquid has a kinematic viscosity of 1.0 mm ² / sec to 5.0 mm ² / sec.
(9)
The electrophoretic device according to any one of (1) to (8), wherein the insulating liquid has a kinematic viscosity of 1.0 mm ² / sec to 3.0 mm ² / sec.
(10)
The porous layer is
A fibrous structure forming the plurality of holes;
The electrophoretic element according to any one of (1) to (9), further comprising non-electrophoretic particles that are held by the fibrous structure and have light reflectivity different from the electrophoretic particles.
(11)
The electrophoretic device according to (10), wherein the fibrous structure is composed of nanofibers.
(12)
The electrophoretic device according to (10) or (11), wherein the fibrous structure is formed by an antistatic method.
(13)
An electrophoretic element is provided between a pair of electrodes,
The electrophoretic element is:
In insulating liquid,
Electrophoretic particles,
And having a light reflectivity different from that of the migrating particles, and a porous layer including a plurality of holes through which the migrating particles pass,
The average pore size of the porous layer is 1.0 to 4.3 times the average particle size of the migrating particles.
(14)
A display device having an electrophoretic element between a pair of electrodes,
The electrophoretic element is:
In insulating liquid,
Electrophoretic particles,
Having a light reflectivity different from that of the migrating particles, and a porous layer including a plurality of holes through which the migrating particles pass,
The average pore diameter of the porous layer is 1.0 to 4.3 times the average particle diameter of the electrophoretic particles.
(15)
The electronic device according to (14), wherein the electronic device is disposed integrally with the clothing article on at least a part of the clothing article.

This application claims priority on the basis of Japanese Patent Application No. 2015- 211728 filed on October 28, 2015 at the Japan Patent Office. The entire contents of this application are incorporated herein by reference. This is incorporated into the application.

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 (14)

1. In insulating liquid,
   Electrophoretic particles,
   And having a light reflectivity different from that of the migrating particles, and a porous layer including a plurality of holes through which the migrating particles pass,
   The electrophoretic element, wherein the porous layer has an average pore size of 1.0 to 4.3 times the average particle size of the electrophoretic particles.
2. The electrophoretic element according to claim 1, wherein an average pore diameter of the porous layer is 3.3 times or more and 4.3 times or less of an average particle diameter of the electrophoretic particles.
3. The electrophoretic device according to claim 1, wherein an average pore diameter of the porous layer is 150 nm or more and 750 nm or less.
4. The porous layer includes a fibrous structure that forms the plurality of pores;
   The electrophoretic element according to claim 1, wherein the fibrous structure includes a portion having a fiber diameter of twice or more the average fiber diameter at a ratio of 20% or less.
5. The porous layer includes a fibrous structure that forms the plurality of pores;
   The electrophoretic element according to claim 1, wherein the fibrous structure includes a portion having a fiber diameter that is twice or more the average fiber diameter at a ratio of 10% or less.
6. The porous layer includes a fibrous structure that forms the plurality of pores;
   The electrophoretic element according to claim 1, wherein the fibrous structure includes a portion having a fiber diameter that is twice or more the average fiber diameter at a ratio of 5% or less.
7. The porous layer includes a fibrous structure that forms the plurality of pores;
   The electrophoretic element according to claim 1, wherein the fibrous structure includes a portion having a fiber diameter of 600 nm or more and 1200 nm or less and a portion having a fiber diameter of 200 nm or more and 500 nm or less.
8. The electrophoretic element according to claim 1, wherein the insulating liquid has a kinematic viscosity of 1.0 mm ² / sec to 5.0 mm ² / sec.
9. The electrophoretic element according to claim 1, wherein the insulating liquid has a kinematic viscosity of 1.0 mm ² / sec to 3.0 mm ² / sec.
10. The porous layer is
    A fibrous structure forming the plurality of holes;
    The electrophoretic element according to claim 1, wherein the electrophoretic element is held by the fibrous structure and has non-electrophoretic particles having light reflectivity different from the electrophoretic particles.
11. The electrophoretic element according to claim 10, wherein the fibrous structure is composed of nanofibers.
12. An electrophoretic element is provided between a pair of electrodes,
    The electrophoretic element is:
    In insulating liquid,
    Electrophoretic particles,
    And having a light reflectivity different from that of the migrating particles, and a porous layer including a plurality of holes through which the migrating particles pass,
    The average pore size of the porous layer is 1.0 to 4.3 times the average particle size of the migrating particles.
13. A display device having an electrophoretic element between a pair of electrodes,
    The electrophoretic element is:
    In insulating liquid,
    Electrophoretic particles,
    Having a light reflectivity different from that of the migrating particles, and a porous layer including a plurality of holes through which the migrating particles pass,
    The average pore diameter of the porous layer is 1.0 to 4.3 times the average particle diameter of the electrophoretic particles.
14. The electronic device according to claim 13, wherein the electronic device is arranged integrally with the clothing article on at least a part of the clothing article.

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