WO2016199618A1

WO2016199618A1 - Display device and electronic apparatus

Info

Publication number: WO2016199618A1
Application number: PCT/JP2016/065975
Authority: WO
Inventors: 小林　健; 貝野　由利子; 綾首藤; 栗原　研一; 美成子渡辺; 英之汲田
Original assignee: ソニー株式会社
Priority date: 2015-06-11
Filing date: 2016-05-31
Publication date: 2016-12-15
Also published as: JP2017003801A

Abstract

A display device according to one embodiment of the present technology uses an insulating liquid containing: positively or negatively charged migrating particles; and a porous layer formed with a fibrous structure and containing non-migrating particles with a light reflectivity different from the migrating particles. The insulating liquid contains a positively-charged basic additive and a negatively-charged acidic additive, and among the basic additive and the acidic additive, a greater amount of the additive having the same charge polarity as the migrating particles is added.

Description

Display device and electronic device

The present technology relates to a display device including an electrophoretic element and an electronic apparatus including the display device.

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 (displays) with low power consumption and high image quality. In particular, recently, the electronic book distribution business has started, and a display with a display quality suitable for reading applications is desired.

As such a display, various displays such as a cholesteric liquid crystal display, an electrophoretic display, an electrooxidation reduction display, and a twist ball display have been proposed, but a reflective display is advantageous for reading applications. . In the reflective display, bright display is performed using reflection (scattering) of external light as in the case of paper, so that display quality closer to that of paper can be obtained.

Among the reflective displays, electrophoretic displays utilizing the electrophoretic phenomenon are expected to be promising candidates because of their low power consumption and fast response speed. As the display method, the following two methods are mainly proposed.

The first method is to disperse two kinds of charged particles in an insulating liquid and move the charged particles according to the electric field. The two kinds of charged particles have different optical reflection characteristics and opposite polarities. In this method, an image is displayed by changing a distribution state of charged particles according to an electric field.

The second method is to disperse charged particles in an insulating liquid and dispose a porous layer (for example, Patent Document 1). In this method, charged particles move through the pores of the porous layer according to the electric field. The porous layer includes, for example, a fibrous structure made of a polymer material and non-migrating particles that are held by the fibrous structure and have different optical reflection characteristics from the charged particles. In such an electrophoretic display, the display is switched by moving charged particles through pores according to an electric field.

JP 2012-22296 A

In such an electrophoretic display including a porous layer and charged particles, a display memory property is required to hold a display image without the charged particles diffusing even after the application of an electric field is stopped. It wasn't. Further, when the display memory property is improved, there is a problem that the responsiveness is lowered.

Therefore, it is desirable to provide a display device and an electronic device that can achieve both excellent responsiveness and high display memory performance.

A display device according to an embodiment of the present technology includes, in an insulating liquid, positive or negatively charged electrophoretic particles and non-electrophoretic particles having light reflectivity different from the electrophoretic particles, and a fibrous structure. The formed porous layer includes a positively charged basic additive and a negatively charged acidic additive in the insulating liquid, and the basic additive and the acidic additive include the migrating particles, More additives with the same charge polarity are added.

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

In the display device that is one embodiment of the present technology and the electronic device that is one embodiment, in the insulating liquid, a basic additive that is positively charged and an acidic additive that is negatively charged are added, and the addition amount thereof The amount of the additive having the same charging polarity as that of the migrating particles was increased. Thereby, the internal electric field generated in the electrophoretic element after the applied electric field is stopped is reduced while suppressing the increase in the viscosity of the insulating liquid.

According to the display device that is one embodiment of the present technology and the electronic device that is one embodiment, in the insulating liquid, a basic additive that is positively charged and an acidic additive that is negatively charged are added. Since many additives having the same charging polarity as that of the particles are added, an internal electric field generated in the electrophoretic element after the applied electric field is stopped is suppressed while suppressing an increase in the viscosity of the insulating liquid. Therefore, it is possible to improve display memory performance while maintaining high responsiveness. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

It is a top view showing the composition of the electrophoretic device concerning one embodiment of this art. It is sectional drawing showing the structure of the electrophoretic element shown in FIG. It is sectional drawing showing the structure of the display apparatus using the electrophoretic element of FIG. It is sectional drawing for demonstrating operation | movement of the display apparatus shown in FIG. 14 is a perspective view illustrating an appearance of application example 1. FIG. FIG. 5B is a perspective view illustrating another example of the electronic book illustrated in FIG. 5A. 12 is a perspective view illustrating an appearance of application example 2. FIG. It represents the shift of the NMR spectrum of a tertiary alkylamine in the presence of an acidic additive. It represents the shift of the NMR spectrum of the tertiary alkylamine with respect to the concentration of the acidic additive. It is a characteristic view showing the relationship between the density | concentration of an acidic additive and the shift amount of a NMR spectrum. It is a characteristic view showing the relationship between the density | concentration of an acidic additive and a self-diffusion coefficient. It is a characteristic view showing the relationship between (acid additive / basic additive) ratio, white reflectance, and response speed. It is a characteristic view showing the relationship between the molecular weight of an additive, white reflectance, and response speed. It is a characteristic view showing the relationship between the kind of amine and the retention of white reflectance.

Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (electrophoretic element)
1-1. Basic configuration 1-2. Action / Effect Application examples (display devices, electronic devices)
3. Example

<1. Embodiment>
(1-1. Basic configuration)
FIG. 1 illustrates a planar configuration of an electrophoretic element (electrophoretic element 1) according to an embodiment of the present technology, and FIG. 2 illustrates a cross-sectional configuration of the electrophoretic element 1. The electrophoretic element 1 generates contrast using an electrophoretic phenomenon and is applied to various electronic devices such as a display device. The electrophoretic element 1 includes an electrophoretic particle 20 that is positively or negatively charged and a porous layer 30 having pores 33 in an insulating liquid 10. In the present embodiment, the insulating liquid 10 further includes an acidic additive 21 A and a basic additive 21 B, and the amount of each added is the same as the charged polarity of the migrating particles 20 in the insulating liquid 10. It is comprised so that the additive which has may increase. 1 and 2 schematically show the configuration of the electrophoretic element 1, and may differ from actual dimensions and shapes.

The insulating liquid 10 is made of, for example, an organic solvent such as paraffin or isoparaffin. One type of organic solvent may be used for the insulating liquid 10, or a plurality of types of organic solvents may be used. It is preferable to make the viscosity and refractive index of the insulating liquid 10 as low as possible. Lowering the viscosity of the insulating liquid 10 improves the mobility (response speed) of the migrating particles 20. In accordance with this, the energy (power consumption) required to move the migrating particles 20 is reduced. When the refractive index of the insulating liquid 10 is lowered, the difference in refractive index between the insulating liquid 10 and the porous layer 30 is increased, and the reflectance of the porous layer 30 is 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 10.

The electrophoretic particles 20 dispersed in the insulating liquid 10 are one or two or more charged particles, and the charged electrophoretic particles 20 move through the pores 33 according to the electric field. The migrating particles 20 have an arbitrary optical reflection characteristic (light reflectance), and a contrast (CR) is generated due to the difference between the light reflectance of the migrating particles 20 and the light reflectance of the porous layer 30. It has become. For example, the migrating particles 20 may be brightly displayed and the porous layer 30 may be darkly displayed, or the migrating particles 20 may be darkly displayed and the porous layer 30 may be brightly displayed.

When the electrophoretic element 1 is viewed from the outside, when the electrophoretic particles 20 are brightly displayed, the electrophoretic particles 20 are visually recognized as, for example, white or a color close to white, and when darkly displayed, for example, the electrophoretic particles 20 are black or black. Visible in close color. The color of the migrating particles 20 is not particularly limited as long as contrast can be generated. For example, it may be red or blue.

The migrating particles 20 are made of particles (powder) such as organic pigments, inorganic pigments, dyes, carbon materials, metal materials, metal oxides, glass, or polymer materials (resins). One type of these may be used for the electrophoretic particle 20, or two or more types may be used. The migrating particles 20 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 20 is preferably, for example, 10 nm or more and 500 nm or less, and more preferably 50 nm or more and 200 nm or less.

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 particle 20 is selected according to, for example, the role that the migrating particle 20 plays to cause contrast. When the migrating particles 20 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 20. When the migrating particles 20 are darkly displayed, the migrating particles 20 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 preferable to use a carbon material for the migrating particles 20. The migrating particles 20 made of a carbon material exhibit excellent chemical stability, mobility, and light absorption.

The content (concentration) of the migrating particles 20 in the insulating liquid 10 is not particularly limited, and is, for example, 0.1 wt% to 10 wt%. In this concentration range, the shielding property and mobility of the migrating particles 20 are ensured. Specifically, when the content of the migrating particles 20 is less than 0.1% by weight, the migrating particles 20 are less likely to shield (conceal) the porous layer 30, and there is a possibility that sufficient contrast cannot be generated. is there. On the other hand, when the content of the electrophoretic particles 20 is more than 10% by weight, the dispersibility of the electrophoretic particles 20 is lowered, and thus the electrophoretic particles 20 are difficult to migrate and may aggregate.

The migrating particles 20 are positively or negatively charged in the insulating liquid 10 and are subjected to a surface treatment in order to improve dispersibility. 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 electrophoretic particles 20 can be maintained by performing a graft polymerization process, a microencapsulation process, or a combination thereof.

For such surface treatment, for example, a material having a functional group capable of being adsorbed on the surface of the migrating particle 20 and a polymerizable functional group (adsorbent material) or the like is used. The adsorbable functional group is determined according to the material for forming the migrating particle 20. For example, when the migrating particles 20 are made of a carbon material such as carbon black, an aniline derivative such as 4-vinylaniline, and when the migrating particles 20 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 20 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 is to disperse the migrating particles 20 in the insulating liquid 10 and retain dispersibility due to the steric hindrance. When the insulating liquid 10 is, for example, paraffin, a branched alkyl group or the like can be used as the dispersing functional group. 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.

It is preferable that the migrating particles 20 are easily dispersed and charged in the insulating liquid 10 over a long period of time and are difficult to be adsorbed on the porous layer 30. For this reason, for example, a dispersant is added to the insulating liquid 10. 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 10 and also causes the electrophoretic particles 20 to move by electrostatic repulsion. It is for dispersing. Examples of such a dispersing agent include Solsperce series manufactured by Lubrizol, BYK series or Anti-Terra series manufactured by BYK-Chemical, or Span series manufactured by TCI America, and Hypermer series manufactured by Croda.

For details on the method of dispersing the migrating particles 20 in the insulating liquid 10, see “Dispersion Technology of Ultrafine Particles and its Evaluation: Surface Treatment / Fine Grinding and Dispersion Stabilization in Air / Liquid / Polymer— Science & Technology)).

In the present embodiment, as described above, the acidic additive 21A and the basic additive 21B are added to the insulating liquid 10 so that the additive having the same charging polarity as the charged polarity of the migrating particles 20 is increased. Has been. Although details will be described later, by adding the acidic additive 21A and the basic additive 21B to the insulating liquid 10, diffusion of the migrating particles 20 after the applied electric field is stopped is suppressed.

The acidic additive 21A has a so-called surfactant structure composed of a hydrophilic part and a hydrophobic part constituted by polar groups. Examples of the polar group include a group having a succinic anhydride structure and a group having a succinic acid structure. The hydrophobic part is composed of, for example, a linear or branched hydrocarbon group having 8 or more carbon atoms. Specific examples include octyl group, nonyl group, decyl group, undecyl group, dodecyl group, vinyl group, allyl group and the like. Specifically, for example, an alkylene succinic anhydride, succinic acid and a succinic acid derivative (for example, sodium di (2-ethylhexyl) sulfosuccinate represented by the following formula (1), (2) or (5); )) Or an alkyl polycarboxylate represented by the formula (4), but not limited thereto. In the formula (1), n is about 5 to 30, and R1 and R2 in the formulas (1) and (2) are a hydrogen atom or an alkyl group. Formula (4) has an ester structure in either the main chain or the side chain. Alternatively, either the main chain or the side chain may be a polycarboxylic acid, or may be a compound represented by the formula (6).

As the basic additive 21B, for example, a primary amine, a secondary amine, or a tertiary amine that is soluble in an organic solvent is preferably used. Moreover, you may use what has a succinimide structure. Specifically, compounds represented by the following formulas (7) to (11), dimethyldecylamine (DMDA, formula (7)), trioctylamine (TOA, formula (8)), 2-ethylhexylamine (EHA, Examples include formula (9)), OLOA 1200 (formula (10)) having n of about 20 to 25, tripropylamine (TPA, formula (11)), and the like. In addition, N-methyldioleylamine, N-methyldodecylamine, dimethyldodecylamine, dimethyldecylamine, dimethyloctylamine, dimethyl (2-ethylhexyl) amine, dimethylhexylamine, dimethylcyclohexylamine, dimethylpentylamine, dimethylbutylamine, Dimethylisopropylamine, dimethylethylamine, trioctylamine, tri (2-ethylhexyl) amine, trihexylamine, triamylamine, tripentylamine, tributylamine, di (2-ethylhexyl) amine, 2-ethylhexylamine, dimethylhexylamine And trihexylamine and the like, but are not limited thereto.

The basic additive 21B is preferably a tertiary amine among the above amines, and the three substituents of the tertiary amine are preferably as bulky as possible and a group having a large steric hindrance. . Thereby, display memory property can be improved more.

In the insulating liquid 10, it is preferable to use at least one of the acidic additive 21A and the basic additive 21B. As described above, the addition amount of the acidic additive 21A and the basic additive 21B is added within a predetermined range depending on the charged polarity of the migrating particles 20. Specifically, when the migrating particles 20 are positively charged, it is preferable to add more basic additive 21B than acidic additive 21A. When the electrophoretic particles 20 are negatively charged, it is preferable to add more acidic additive 21A than basic additive 21B. The acidic additive 21 A is negatively charged in the insulating liquid 10, and the basic additive 21 B is positively charged in the insulating liquid 10. That is, in the present embodiment, the acidic additive 21A and the basic additive 21B may be added so as to include a large amount of an additive having the same charging polarity as that of the electrophoretic particle 20 in the insulating liquid 10. preferable.

It is preferable that the addition amount ratio between the acidic additive 21A and the basic additive 21B is as follows depending on the charged polarity of the migrating particles 20. When the charged polarity of the migrating particles 20 is positive, the addition amount ratio of the basic additive 32B to the acidic additive 32A (acid additive 32A / basic additive 32B) is, for example, 3 in terms of molar amount. Larger than 20 and preferably smaller than 20. When the charged polarity of the migrating particles 20 is negative, the additive amount ratio of the acidic additive 32A to the basic additive 32B (basic additive 32B / acid additive 32A) is, for example, 3 in terms of molar amount. Larger than 20 and preferably smaller than 20. By setting such a ratio, the basic additive 21B is easily charged in the insulating liquid 10, and an increase in the viscosity of the insulating liquid 10 is suppressed.

The molecular weights of the acidic additive 21A and the basic additive 21B are preferably as small as possible in order to suppress an increase in the dielectric constant of the electrophoretic element 1, and are preferably smaller than 1000, for example. However, from the viewpoint of volatility, the molecular weight of the acidic additive 21A and the basic additive 21B is preferably at least greater than 100.

The porous layer 30 can shield the migrating particles 20 and has a fibrous structure 31 and non-migrating particles 32 held by the fibrous structure 31. The porous layer 30 is a three-dimensional structure (an irregular network structure such as a nonwoven fabric) formed by a fibrous structure 31, and is provided with a plurality of gaps (pores 33). By forming the three-dimensional structure of the porous layer 30 with the fibrous structure 31, light (external light) is irregularly reflected (multiple scattering), and the reflectance of the porous layer 30 is increased. Therefore, even when the thickness of the porous layer 30 is small, a high reflectance can be obtained, the contrast of the electrophoretic element 1 can be improved, and the energy required to move the electrophoretic particles 20 can be reduced. Further, the average pore diameter of the pores 33 is increased, and many pores 33 are provided in the porous layer 30. Thereby, the migrating particles 20 are easily moved via the pores 33, the response speed is improved, and the energy necessary for moving the migrating particles 20 is further reduced. The thickness of such a porous layer 30 is, for example, 5 μm to 100 μm.

The fibrous structure 31 is a fibrous substance having a sufficient length with respect to the fiber diameter (diameter). For example, a plurality of fibrous structures 31 are assembled and randomly overlapped to form the porous layer 30. One fibrous structure 31 may be entangled randomly to form the porous layer 30. Or the porous layer 30 by the one fibrous structure 31 and the porous layer 30 by the some fibrous structure 31 may be mixed.

The fibrous structure 31 extends linearly, for example. The shape of the fibrous structure 31 may be any shape. For example, the fibrous structure 31 may be crimped or bent in the middle. Or the fibrous structure 31 may be branched on the way.

The minimum fiber diameter of the fibrous structure 31 is, for example, preferably 500 nm or less, and more preferably 300 nm or less. The average fiber diameter is preferably 0.1 μm or more and 10 μm or less, for example, but may be outside the above range. By reducing the average fiber diameter, light is easily diffusely reflected, and the pore diameter of the pores 33 is increased. The fiber diameter is determined so that the fibrous structure 31 can hold the non-migrating particles 32. The average fiber diameter can be measured, for example, by microscopic observation using a scanning electron microscope or the like. The average length of the fibrous structure 31 is arbitrary. The fibrous structure 31 is formed by, 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 done. By using such a method, the fibrous structure 31 having a sufficient length with respect to the fiber diameter can be easily and stably formed.

The fibrous structure 31 is formed of at least one of a polymer material and an inorganic material, and is particularly preferably 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 a nanofiber as the fibrous structure 31, light is easily diffusely reflected, and the reflectance of the porous layer 30 can be further improved. That is, the contrast of the electrophoretic element 1 can be improved. Further, in the fibrous structure 31 made of nanofibers, the proportion of the pores 33 in the unit volume increases, and the migrating particles 20 can easily move through the pores 33. Therefore, the energy required for moving the migrating particles 20 can be reduced. The fibrous structure 31 made of nanofibers is preferably formed by an electrostatic spinning method. By using the electrostatic spinning method, the fibrous structure 31 having a small fiber diameter can be easily and stably formed.

It is preferable to use a fibrous structure 31 having a light reflectance different from that of the migrating particles 20. Thereby, the contrast by the difference in the light reflectance of the porous layer 30 and the migrating particles 20 is easily formed. A fibrous structure 31 that exhibits optical transparency (colorless and transparent) in the insulating liquid 10 may be used.

The pore 33 is configured by overlapping a plurality of fibrous structures 31 or entwining one fibrous structure 31. The pores 33 preferably have as large an average pore diameter as possible so that the migrating particles 20 can easily move through the pores 33. The average pore diameter of the pores 33 is, for example, not less than 0.1 μm and not more than 10 μm.

Non-electrophoretic particles 32 are one or more particles that are fixed to the fibrous structure 31 and do not undergo electrophoresis. The non-migrating particles 32 may be embedded in the held fibrous structure 31 or may be partially exposed from the fibrous structure 31.

As the non-electrophoretic particles 32, those having a light reflectance different from that of the electrophoretic particles 20 are used. The non-migrating particles 32 can be made of the same material as that of the migrating particles 20. Specifically, when the non-electrophoretic particle 32 (porous layer 30) displays brightly, the material when the electrophoretic particle 20 displays brightly, and when the non-electrophoretic particle 32 displays dark, the electrophoretic particle 20 darkens. Each material for display can be used. When performing a bright display with the porous layer 30, it is preferable that the non-migrating particles 32 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 32 and the migrating particles 20 may be the same or different. The color visually recognized from the outside when the non-electrophoretic particle 32 performs bright display or dark display is the same as that described for the electrophoretic particle 20.

Such a porous layer 30 can be formed by the following method, for example. First, for example, a constituent material of the fibrous structure 31 such as a polymer material is dissolved in an organic solvent to prepare a spinning solution. Next, the non-migrating particles 32 are added to the spinning solution and stirred sufficiently to disperse the non-migrating particles 32. Finally, the spinning solution is spun by, for example, an electrostatic spinning method to fix the non-migrating particles 22 to the fibrous structure 31, thereby forming the porous layer 30. The porous layer 30 may be formed by drilling a polymer film using a laser to form the pores 33. The porous layer 30 may be a cloth knitted with synthetic fibers or the like on the porous layer 30 or continuous. A foam porous polymer or the like may be used.

As described above, the electrophoretic element causes contrast due to the difference between the light reflectance of the migrating particles and the light reflectance of the porous layer. Specifically, among the migrating particles and the porous layer, the light reflectance for bright display is higher than the light reflectance for dark display. By performing such a display, the light reflectance at the time of bright display is remarkably increased by utilizing the irregular reflection of light by the porous layer (three-dimensional structure). Accordingly, the contrast is remarkably improved accordingly.

In the electrophoretic element, specifically, the display is performed when the migrating particles exhibit the following behavior. When a voltage is applied between the pair of electrodes, the migrating particles move to the corresponding electrode side through the pores of the porous layer within the range of the electric field generated thereby. Depending on the area where the migrating particles have moved or not moved, either bright display or dark display is performed, and an image is displayed. It is preferable that the light reflectance of the non-electrophoretic particles is higher than that of the electrophoretic particles so that the porous layer displays light and the electrophoretic particles display dark.

(1-2. Action and effect)
As described above, the reflection type display using an electrophoretic element is a low power consumption, a high response speed, and a light weight display quality close to that of paper. Although it is expected as a promising candidate, further reduction of power consumption is desired. As a method for reducing power consumption, an improvement in display memory performance can be mentioned. In the electrophoretic element, even after the applied electric field (applied electric field) is stopped, the electrophoretic particles remain on the moved electrode side, so that the display image is retained and the display memory property is exhibited. However, in a general electrophoretic element, when the applied voltage is stopped, diffusion of the electrophoretic particles starts, and a sufficient display memory property cannot be obtained.

In such an electrophoretic element, when the basic additive is excessively added to the insulating liquid, the response speed increases, but the display memory property tends to decrease. On the other hand, when an acidic additive is added to the insulating liquid, although the display memory property is exhibited, the electrophoretic element tends to be adsorbed to the fibrous structure, and the response speed tends to be remarkably reduced. Further, when both the basic additive and the acidic additive were added to the insulating liquid in the same amount, the display memory property was improved but the response speed tended to decrease.

On the other hand, in the electrophoretic element 1 of the present embodiment, the basic additive 21B that is positively charged and the acidic additive 21A that is negatively charged are added to the insulating liquid 10, and the addition amount thereof is as follows. The amount of the additive having the same charging polarity as the charging polarity of the electrophoretic particles 20 that are positively or negatively charged is increased. Thereby, the internal electric field generated in the electrophoretic element 1 after the applied electric field is stopped is reduced while suppressing the increase in the viscosity of the insulating liquid 10. Specifically, the internal electric field (electric field in the direction opposite to the applied electric field) generated after application of the electric field is alleviated by the movement of the acidic additive 21A and the basic additive 21B having higher mobility than the migrating particles 20, and migration. Diffusion of the particles 20 is suppressed.

As described above, in the electrophoretic element 1 of the present embodiment, the acidic additive 21 A and the basic additive 21 B in the insulating liquid 10 are increased in the number of additives having the same charging polarity as the charging polarity of the migrating particles 20. Were added. Thereby, the internal electric field generated in the electrophoretic element after the applied electric field is stopped is reduced while suppressing the increase in the viscosity of the insulating liquid 10. Therefore, it is possible to improve display memory performance while maintaining high responsiveness.

Also, with the above configuration, the diffusion of the migrating particles 20 after the applied electric field is stopped is suppressed, so that the white reflectance of the electrophoretic element 1 is improved.

<2. Application example>
(Display device)
Next, an application example of the electrophoretic element 1 will be described. The electrophoretic element 1 is applied to a display device, for example.

FIG. 3 shows an example of a cross-sectional configuration of a display device (display device 2) using the electrophoretic element 1. The display device 2 is an electrophoretic display (so-called electronic paper display) that displays an image (for example, character information) using an electrophoretic phenomenon, and an electrophoretic element between a driving substrate 40 and a counter substrate 50. 1 is provided. A space between the driving substrate 40 and the counter substrate 50 is adjusted to a predetermined distance by a spacer 60.

The drive substrate 40 has, for example, a TFT (Thin Film Transistor) 32, a protective layer 43, a planarization insulating layer 44, and a pixel electrode 45 in this order on one surface of the plate-like member 41. The TFTs 42 and the pixel electrodes 45 are arranged in a matrix or a segment, for example, depending on the pixel arrangement.

The plate-like member 41 is made of, for example, an inorganic material, a metal material, a plastic material, or the like. As the inorganic materials, for example, silicon (Si), silicon oxide _(SiO X), silicon nitride (SiN _X) or aluminum oxide (AlO _x), and the like. 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 2, since an image is displayed on the counter substrate 50 side, the plate-like member 41 may be non-light transmissive. The plate-like member 41 may be constituted by a rigid substrate such as a wafer, or may be constituted by a flexible thin layer glass or film. By using a flexible material for the plate-like member 41, a flexible display device 2 can be realized.

The TFT 42 is a switching element for selecting a pixel. The TFT 42 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 43 and the planarization insulating layer 44 are made of an insulating resin material such as polyimide, for example. If the surface of the protective layer 43 is sufficiently flat, the planarization insulating layer 44 can be omitted. The pixel electrode 45 is made of, for example, a metal material such as gold (Au), silver (Ag), or copper (Cu). The pixel electrode 45 is connected to the TFT 42 through a contact hole (not shown) provided in the protective layer 43 and the planarization insulating layer 44.

The counter substrate 50 includes, for example, a plate-like member 51 and a counter electrode 52, and the counter electrode 52 is provided on the entire surface of the plate-like member 51 (the surface facing the drive substrate 40). The counter electrode 52 may be arranged in a matrix or a segment like the pixel electrode 45.

The plate member 51 is made of the same material as the plate member 41 except that it is light transmissive. For the counter electrode 52, for example, a light-transmitting conductive material such as indium oxide-tin oxide (ITO), antimony-tin oxide (ATO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO). (Transparent electrode material) can be used.

When displaying an image on the counter substrate 50 side, the electrophoretic element 1 is viewed through the counter electrode 52. Therefore, the light transmittance (transmittance) of the counter electrode 52 is preferably as high as possible. 80% or more. Further, the electric resistance of the counter electrode 52 is preferably as low as possible, for example, 100Ω / □ or less.

The electrophoretic element 1 has the same configuration as the electrophoretic element 1 of the above-described embodiment and modification. Specifically, the electrophoretic element 1 includes electrophoretic particles 20 and a porous layer 30 having a plurality of pores 33 in an insulating liquid 10. The insulating liquid 10 is filled in a space between the driving substrate 40 and the counter substrate 50, and the porous layer 30 is supported by a spacer 60, for example. The space filled with the insulating liquid 10 is divided into, for example, a retreat area R1 near the pixel electrode 45 and a display area R2 near the counter electrode 52 with the porous layer 30 as a boundary. . The configurations of the insulating liquid 10, the migrating particles 20, and the porous layer 30 are the same as those described in the above embodiments and the like. Note that, in FIG. 3 and FIG. 4 described later, only a part of the pore 33 is shown in order to simplify the illustrated content.

The porous layer 30 may be adjacent to either the pixel electrode 45 or the counter electrode 52, and the retreat area R1 and the display area R2 may not be clearly separated. The migrating particles 20 move toward the pixel electrode 45 or the counter electrode 52 according to the electric field.

The thickness of the spacer 60 is, for example, 10 μm to 100 μm, and is preferably as thin as possible. Thereby, power consumption can be suppressed. The spacer 60 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 40 and the counter substrate 50. The arrangement shape of the spacer 60 is not particularly limited, but it is preferable that the spacer 60 is provided so as not to disturb the movement of the migrating particles 20 and to uniformly distribute the migrating particles 20.

In the display device 2 in the initial state, the migrating particles 20 are arranged in the retreat area R1 (FIG. 3). In this case, since the migrating particles 20 are shielded by the porous layer 30 in all the pixels, no contrast is generated when the electrophoretic element 1 is viewed from the counter substrate 50 side (an image is not displayed). Is in a state.

On the other hand, when a pixel is selected by the TFT 42 and an electric field is applied between the pixel electrode 45 and the counter electrode 52, as shown in FIG. 4, the migrating particles 20 are moved from the retreat area R 1 to the porous layer 30 for each pixel. It moves to display area R2 via (pore 33). In this case, since the migrating particles 20 are both shielded by the porous layer 30 and not shielded, the contrast is generated when the electrophoretic element 1 is viewed from the counter substrate 50 side. become. Thereby, an image is displayed.

According to the display device 2, the electrophoretic element 1 having a high response speed can display a high-quality image suitable for colorization and moving image display, for example.

(Electronics)
Next, an application example of the display device 2 will be described.

The display device 2 of the present technology can be applied to electronic devices for various uses, and the type of the electronic device is not particularly limited. This display device 2 can be mounted on, for example, the following electronic devices. However, the configuration of the electronic device described below is merely an example, and the configuration can be changed as appropriate.

(Application example 1)
5A and 5B 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. The operation unit 130 may be provided on the front surface of the non-display unit 120 as illustrated in FIG. 5A or may be provided on the upper surface as illustrated in FIG. 5B. The display unit 110 includes the display device 2. The display device 2 may be mounted on a PDA (Personal Digital Assistants) having the same configuration as the electronic book shown in FIGS. 5A and 5B.

(Application example 2)
FIG. 6 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 2.

<3. Example>
(Experiment 1-1)
Next, an experiment was conducted to verify the interaction between the acidic additive and the basic additive and the action mechanism of each additive in the dispersion medium.

Responsiveness and display memory performance of the electrophoretic element are affected by the mobility of the electrophoretic particles passing through the porous layer and the ease of redispersion of the electrophoretic particles from the electrode surface when the applied electric field is erased. In order to achieve both excellent responsiveness and high display memory performance, in addition to the surface modification of migrating particles, development of additives such as dispersion media and electric field compensators, dispersants, charge compensation agents, etc. to be added to the dispersion media is important. In developing these materials, it is important to verify the interaction between migrating particles and additives. However, since the migrating particles are, for example, a magnetic substance mainly composed of a Cu—Fe—Mn composite oxide, a detailed analysis of the NMR spectrum is impossible with a sample solution containing the migrating particles. Therefore, in this experiment, a sample (sample A) using tertiary alkylamine as a basic additive and a sample (sample B) added with succinic acid as an acidic additive together with tertiary alkylamine were prepared. NMR was measured and the interaction between acidic and basic additives was observed. FIG. 7 is an enlarged view of a part of the ¹ H-NMR spectrum of Sample A and Sample B. Further, the self-diffusion coefficients of Sample A and Sample B were measured and the results are summarized in Table 3.

Tables 1 and 2 summarize the compositions (Table 1) and measurement conditions (Table 2) of Sample A and Sample B. The NMR apparatus used was ECA-500 model manufactured by JEOL, and the probe used was a TH5AT probe. When the solvent was an isoparaffin solvent, the shim was adjusted by ¹ H Selective gradient shimming without magnetic field lock.

The PFG-LED + BPPSTE method used here is the BPP method (Bipolar-Pulse-Pair) or LED method (Longitudinal-Eddy-Current-Delay), which suppresses the influence of eddy current on the basic Spin-Echo method, and the lateral relaxation time T ₂ Combined with STE method (Stimulated-Echo) which is effective for short-wavelength systems and systems affected by J modulation (for details, see CS Johnson Jr, Prog. NMR. Spectrosc. 1999, 34, 203.) . The sample tube was adjusted to a liquid height of 5 mm using a convection effect removing double tube (5 mmφ). The self-diffusion coefficient was analyzed based on the Stejskal equation (number (1)) (E. O. Stejskal, J. E. Tanner, J. Chem. Phys. 1965, 42, 288.). The formulas and setting values for each parameter are shown below.

(Equation 1)
I (g) = I (0) exp (− (γgδ) ² D (Δ−Δ / 3)) (1)

(I: peak intensity, gamma: gyromagnetic ratio of the measurement nuclei ⁽¹ H), g: FG strength, [delta]: FG pulse width, delta: diffusion time, D: self-diffusion coefficient)

In the ¹ H-NMR spectrum shown in FIG. 7, the 2.32 ppm signal of Sample A is derived from the proton of the methylene group adjacent to N of the tertiary alkylamine. As can be seen from FIG. 7 and Table 3, in the methylene group signal of alkylamine, a large low magnetic field shift and remarkable broadening were observed in the presence of succinic acid, and in addition, a significant decrease in self-diffusion coefficient was observed. Therefore, when succinic acid coexists with alkylamine, it is presumed that interaction occurs.

(Experiment 1-2)
Further, samples B-1 to B-7 were prepared in which the alkylamine concentration was fixed (1.5 wt%) and the succinic acid concentration was changed from 0 to 6.5 wt%, and the ¹ H-NMR spectrum and The self-diffusion coefficient was measured by PFG-NMR. Table 4 summarizes the succinic acid concentration contained in each sample, the low magnetic field shift amount of the N adjacent methylene group in the ¹ H-NMR spectrum of the alkylamine, and the value of the self-diffusion coefficient. FIG. 8 shows a part of the ¹ H-NMR spectrum of Samples B-1 to B-7 together with Sample A. In addition, the results of NMR measurement after leaving Sample B-3 at 70 ° C. overnight (Sample B-3 ′) are also shown.

From FIG. 8 and Table 4, when the succinic acid concentration is 0 to 7 wt%, the signal (2.28 ppm) derived from N—CH ₂ — of the alkylamine is gradually shifted to the lower magnetic field side, and the alkylamine A drastic decrease in self-diffusion coefficient was observed. On the other hand, when the succinic acid concentration was higher than 7 wt%, the signal derived from N—CH ₂ — became substantially constant at 2.9 ppm, and the decrease in the self-diffusion coefficient of alkylamine was moderate. In addition, even when left overnight, there was no change in the low magnetic field shift. This shows that there is no history due to heat treatment.

FIG. 9 shows the relationship between the shift amount of the signal derived from N—CH ₂ — of the alkylamine and the succinic acid concentration (mol concentration) in the ¹ H-NMR spectrum, and FIG. It shows the relationship between the decrease in the self-diffusion coefficient and the succinic acid concentration (converted to a molar concentration). From FIG. 9 and FIG. 10, it was found that the tendency changes greatly in the vicinity of the succinic acid concentration of 0.2 mol / L (7 wt%) with respect to the alkylamine concentration of 0.1 mol / L (1.5 wt%).

The low magnetic field shift of the signal derived from N—CH ₂ — of the alkylamine observed here is presumed to be caused by the tertiary amine of the alkylamine becoming an ammonium ion by the addition of the acid succinic acid. Is done. Specifically, the tertiary amine of the alkylamine becomes an ammonium ion, so that the electron density on the N atom decreases, the adjacent methylene group is shielded, and the signal derived from N-CH2- shifts to a low magnetic field. It is thought that. This is because the alkylamine and succinic acid in the isoparaffinic solvent are in an electrically neutral state by themselves, but they are in a state of being charged with each other due to their coexistence (interaction). Conceivable. Thereby, succinic acid becomes active as an internal electric field compensation additive. The decrease in the self-diffusion coefficient that occurs simultaneously with the low magnetic field shift can be explained by the fact that both formed ion aggregates and the apparent molecular radius of the alkylamine was increased.

From the above, the succinic acid concentration (relative to the alkylamine) in which the chemical shift amount of the signal derived from N—CH ₂ — of the alkylamine in the ¹ H-NMR spectrum and the tendency of change in the self-diffusion coefficient of the alkylamine greatly change. A succinic acid weight ratio of 1: 5 and a molar ratio of 1: 2) was found to be the minimum amount of succinic acid necessary for all the alkylamine to ionize. On the other hand, it was also found that the presence of excess succinic acid caused a further decrease in the self-diffusion coefficient of alkylamine. That is, it is presumed that the viscosity increases when a basic additive and an acidic additive are added to the insulating liquid of the electrophoretic element. This is considered to be a cause of reducing the migration characteristics (responsiveness) of the migrating particles. The weight ratio of the alkylamine and succinic acid is substantially the same as the ratio of the material composition at which the device performance of the electrophoretic element shows the optimum value (alkylamine: succinic acid weight ratio = 1: 6).

(Experiment 2-1)
Next, embodiments of the present technology will be described in detail. By the following procedure, a display device was manufactured using black (dark display) migrating particles and a white (bright display) porous layer (particle-containing fibrous structure).

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 applied 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 (at 6000 rpm for 10 minutes) 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 negatively charged dispersing group 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 insulating liquid to prepare solution A. 1 g of the migrating particles was added to 9 g of this solution A, and ultrasonic dispersion was performed. This dispersion was centrifuged (at 6000 rpm for 90 minutes) and decanted, and then redispersed in an insulating liquid. This operation was repeated three times, and a solution B was prepared so that the electrophoretic particle component in the obtained dispersion was 10% by weight. Next, 0.25 g of the basic additive alkylamine and 0.12 g of the acidic additive are added to 49.6 g of the insulating liquid in 50 g of the solution B and stirred, and the migrating particles, the acidic additive, and the basic additive are respectively added. , 0.4 mmol (acidic additive) and 1.75 mmol (basic additive) were obtained.

Next, polymethyl methacrylate was prepared as a constituent material of the fibrous structure. After 14 g of this polymethyl methacrylate was dissolved in 86 g of N, N′-dimethylformamide, 30 g of titanium oxide having a primary particle size of 250 nm as non-electrophoretic particles was added to 70 g of this solution and mixed by a bead mill. As a result, a spinning solution for forming a fibrous structure was obtained. After a pixel electrode made of ITO having a predetermined pattern was formed on the driving substrate, spinning was performed using this spinning solution. Specifically, the spinning solution was put into a syringe, and spinning was performed for 1.2 mg / cm ² on the driving substrate. Through the above steps, a porous layer (a fibrous structure holding non-electrophoretic particles) was formed on the drive substrate. Spinning was performed using an electrospinning apparatus (NANON manufactured by MEC Co., Ltd.).

After forming the porous layer on the driving substrate, the unnecessary porous layer was removed from the driving substrate. Specifically, the porous layer where the pixel electrode is not provided was removed. As a counter substrate, a counter electrode made of ITO was formed on a plate-like member, a spacer of PET film (30 μm thick) was placed on the counter substrate, and this was then overlapped with a drive substrate on which a porous layer was formed. At this time, the porous layer was separated from the pixel electrode and the counter electrode by holding the porous layer with the spacer. Next, an insulating liquid in which the migrating particles were dispersed was injected between the driving substrate and the counter substrate. Finally, ultraviolet light was applied to the photocurable resin to complete a display device (Sample 3-1).

In addition, samples 3-2 to 3-9 having different contents of acidic additive and basic additive were prepared, and the white reflectance (%) and response speed were measured. The results are shown in Table 5 and FIG. Indicated.

From FIG. 11 and Table 5, when the migrating particles are negatively charged in the insulating liquid, the addition amount (mol) ratio of the acidic additive to the basic additive (basic additive / acid additive) is: For example, it is preferably larger than 1.9 and smaller than 33.4, more preferably larger than 3 and smaller than 20. In order to reduce the increase in the dielectric constant of the electrophoretic element, it is preferable that the additive amount be small.

(Experiment 2-2)
A display device was prepared using the same method as above except that basic additives having various molecular weights were used, and the white reflectance (%) and response speed with respect to the molecular weight of the basic additive were measured. Are shown in Table 6 and FIG. The molecular weight of the acidic additive used for each sample is 310.

FIG. 12 and Table 6 show that the response speed decreases as the molecular weight of the basic additive increases. Sample 4-1 using a basic additive having a small molecular weight (less than 100) was difficult to be made into a device.

(Experiment 2-3)
A display device was prepared using the same method as above except that tertiary amine (sample 5-1), secondary amine (sample 5-2), and primary amine (sample 5-3) were used as basic additives. This was manufactured and the retention time of the white reflectance was measured. The results are shown in Table 7 and FIG. The molecular weight of the basic additive is the same for all samples 5-1 to 5-3 (molecular weight 143).

From FIG. 13 and Table 7, it was found that tertiary amine is most preferable as the basic additive.

In Experiment 2, the experiment was carried out using negatively charged migrating particles. However, in Table 8 shown below, the positively charged migrating particles have an additive amount ratio between the acidic additive and the basic additive. It can be seen that the display characteristics can be improved by reversing the case of using negatively charged electrophoretic particles.

Although the present technology has been described with reference to the embodiments and examples, the present technology is not limited to the above-described embodiments 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 technology can also have the following configurations.
(1) A porous layer formed of a fibrous structure, which includes positively or negatively charged electrophoretic particles in the insulating liquid and non-electrophoretic particles having light reflectivity different from the electrophoretic particles, A positively charged basic additive and a negatively charged acidic additive in the insulating liquid, the basic additive and the acidic additive having the same charging polarity as the migrating particles A display device to which more is added.
(2) The display device according to (1), wherein a molar ratio of the acidic additive to the basic additive when the electrophoretic particles are negatively charged is greater than 3 and less than 20.
(3) The display device according to (1), wherein a molar ratio of the basic additive to the acidic additive when the electrophoretic particles are positively charged is greater than 3 and less than 20.
(4) The display device according to any one of (1) to (3), wherein molecular weights of the basic additive and the acidic additive are larger than 100 and smaller than 1000.
(5) The display device according to any one of (1) to (4), wherein the acidic additive has a succinic anhydride structure.
(6) The display device according to any one of (1) to (4), wherein the acidic additive has a succinic acid structure.
(7) The display device according to any one of (1) to (6), wherein the basic additive is an amine.
(8) The display device according to any one of (1) to (7), wherein each of the acidic additive and the basic additive includes a plurality of types.
(9) The display device according to any one of (1) to (8), wherein an average fiber diameter of the fibrous structure is 0.1 μm or more and 10 μm or less.
(10) The display device according to any one of (1) to (9), wherein the fibrous structure is formed by an antistatic method.
(11) The light reflectance of the non-electrophoretic particles is higher than the light reflectance of the electrophoretic particles, the electrophoretic particles perform dark display, and the non-electrophoretic particles and the fibrous structure perform light display. The display device according to any one of (10).
(12) The migrating particles and the non-migrating particles are composed of at least one of an organic pigment, an inorganic pigment, a dye, a carbon material, a metal material, a metal oxide, glass, and a polymer material. The display device according to any one of (1) to (11).
(13) The display device according to any one of (1) to (12), wherein the fibrous structure is formed of at least one of a polymer material and an inorganic material.
(14) A display device is provided, and the display device includes electrophoretic particles charged positively or negatively and non-electrophoretic particles having light reflectivity different from the electrophoretic particles, and a fibrous structure. A porous layer formed by a body, and in the insulating liquid, a positively charged basic additive and a negatively charged acidic additive, the basic additive and the acidic additive, Electronic equipment to which more additives having the same charging polarity as the migrating particles are added.

This application claims priority on the basis of Japanese Patent Application No. 2015-118106 filed on June 11, 2015 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

In insulating liquid,
Positively or negatively charged migrating particles,
A non-electrophoretic particle having light reflectivity different from the electrophoretic particle, and a porous layer formed of a fibrous structure;
In the insulating liquid, including a positively charged basic additive and a negatively charged acidic additive,
A larger amount of the basic additive and the acidic additive are added to the additive having the same charging polarity as the electrophoretic particles.
The display device according to claim 1, wherein a molar ratio of the acidic additive to the basic additive when the electrophoretic particles are negatively charged is greater than 3 and less than 20.
The display device according to claim 1, wherein a molar ratio of the basic additive to the acidic additive when the electrophoretic particles are positively charged is greater than 3 and less than 20.
The display device according to claim 1, wherein the molecular weight of the basic additive and the acidic additive is larger than 100 and smaller than 1000.
The display device according to claim 1, wherein the acidic additive has a succinic anhydride structure.
The display device according to claim 1, wherein the acidic additive has a succinic acid structure.
The display device according to claim 1, wherein the basic additive is an amine.
The display device according to claim 1, comprising a plurality of types of the acidic additive and the basic additive.
The display device according to claim 1, wherein an average fiber diameter of the fibrous structure is 0.1 μm or more and 10 μm or less.
The display device according to claim 1, wherein the fibrous structure is formed by an antistatic method.
2. The display device according to claim 1, wherein the light reflectance of the non-electrophoretic particles is higher than the light reflectance of the electrophoretic particles, the electrophoretic particles perform dark display, and the non-electrophoretic particles and the fibrous structure perform bright display. .
The electrophoretic particles and the non-electrophoretic particles are composed of at least one of an organic pigment, an inorganic pigment, a dye, a carbon material, a metal material, a metal oxide, glass, and a polymer material. The display device described in 1.
The display device according to claim 1, wherein the fibrous structure is formed of at least one of a polymer material and an inorganic material.
A display device,
The display device
In insulating liquid,
Positively or negatively charged migrating particles,
A non-electrophoretic particle having light reflectivity different from the electrophoretic particle, and a porous layer formed of a fibrous structure;
In the insulating liquid, including a positively charged basic additive and a negatively charged acidic additive,
An electronic device in which the basic additive and the acidic additive are added more in the same charge polarity as the migrating particles.