JP2008134536A - Display medium and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display medium the deterioration of whose contrast is restrained, so that the visibility of the display medium can be restrained from being deteriorated at a dark place and to provide a display device. <P>SOLUTION: A group 34 of particles moving between a front surface substrate 20 and a back surface substrate 22 of the display medium 12 according to an electric field formed between the front surface and back surface substrates and a dispersion medium 50 for dispersing the group 34 of particles are inserted and sealed between the front surface and back surface substrates. A gap through which the group 34 of particles are made to pass is arranged between the front surface and back surface substrates and a reflecting member 28 which is different from the group 34 of particles and has optical reflection characteristics is inserted and sealed between the front surface and back surface substrates. At least one of a fluorescent material and a luminous material is incorporated in the reflecting member 28. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a display medium and a display device.

Conventionally, display media using colored particles are known as display media that can be rewritten repeatedly.
The display medium includes, for example, a pair of substrates and a group of particles sealed between the substrates so as to be movable between the substrates in accordance with an electric field formed between the pair of substrates. Further, a gap member for partitioning the substrates into a plurality of cells may be provided between the substrates for the purpose of preventing the particles from being biased to a specific region in the substrates.

  The particle group enclosed between the pair of substrates is a single type of particle group colored in a specific color, or a plurality of types of particle groups having different colors and different electric field strengths required for movement, etc. There is.

  In this display medium, encapsulated particles are moved by applying a voltage between a pair of substrates. Then, by reflecting the incident light from the outside of the display medium to the particle group and recognizing the color, an image of a color corresponding to the amount of particles moved to one of the substrates and the color of the moved particles Is displayed.

  In this display medium, as a technique for improving visibility in a dark place, a technique in which a self-luminous substance is contained in a medium in which particles moving between substrates are dispersed (for example, Patent Document 1). (See, for example, Patent Document 2), or a technique in which a substrate forming a display medium contains a fluorescent material or a phosphorescent material. (For example, refer to Patent Document 3).

Japanese Patent Laid-Open No. 2002-40489 JP 2002-287174 A JP 2004-310074 A

  An object of the present invention is to provide a display medium and a display device capable of suppressing a decrease in contrast and suppressing a decrease in visibility in a dark place.

The above problem is solved by the following means. That is,
According to a first aspect of the present invention, there is provided a pair of substrates having at least one of translucency and disposed with a gap, and sealed between the pair of substrates, and between the substrates according to an electric field formed between the substrates. A particle group that moves between the pair of substrates, a dispersion medium that disperses the particle group, and a gap that is disposed between the pair of substrates and through which the particle group passes. A reflective member having an optical reflection characteristic different from that of the group, the reflective member containing at least one of a phosphorescent material and a fluorescent material.

  The invention according to claim 2 is the display medium according to claim 1, wherein the color of the reflecting member is white.

  The invention according to claim 3 is the display medium according to claim 1, wherein the reflecting member is constituted by an aggregate of particles.

  According to a fourth aspect of the present invention, in the display medium according to the first aspect, the reflective member is constituted by an aggregate of particles having a volume average primary particle size larger than the particles of the particle group. It is a medium.

  The invention according to claim 5 is the display medium according to claim 1, wherein the reflecting member is formed of a porous member having a through hole through which the particle group passes.

  The invention according to claim 6 is the display medium according to claim 1, wherein the reflection member is disposed with a gap between the pair of substrates.

  The invention according to claim 7 is the display medium according to claim 1, wherein the reflecting member is unevenly distributed on one of the pair of substrates.

  According to an eighth aspect of the present invention, there is provided a pair of substrates, at least one of which has translucency and disposed with a gap, and a space between the substrates according to an electric field formed between the pair of substrates and sealed between the pair of substrates. A particle group that moves between the pair of substrates, a dispersion medium that disperses the particle group, and a gap that is disposed between the pair of substrates and through which the particle group passes. An electric field that has a display medium having a reflection member having optical reflection characteristics different from that of the group, the reflection member containing at least one of a phosphorescent material and a fluorescent material, and forms an electric field between the pair of substrates A display device comprising a forming unit.

  The invention according to claim 9 is the display device according to claim 8, wherein the color of the reflecting member is white.

  The invention according to claim 10 is the display device according to claim 8, wherein the reflection member is constituted by an aggregate of particles.

  An invention according to claim 11 is the display device according to claim 8, wherein the reflecting member is constituted by an aggregate of particles having a volume average primary particle size larger than particles of the particle group. Device.

  A twelfth aspect of the present invention is the display device according to the eighth aspect, wherein the reflecting member is a porous member having a through-hole through which the particle group passes.

  A thirteenth aspect of the present invention is the display device according to the eighth aspect, wherein the reflecting member is disposed with a gap between the pair of substrates.

  The invention according to claim 14 is the display device according to claim 8, wherein the reflection member is unevenly distributed on one of the pair of substrates.

  According to the invention which concerns on Claim 1, compared with the case where a reflecting member does not contain at least one of a luminous material and a fluorescent material, the effect that the fall of contrast can be suppressed and the fall of the visibility in a dark place can be suppressed. Play.

  According to the invention which concerns on Claim 2, compared with the case where the reflecting member does not contain at least one of the phosphorescent material and the fluorescent material, it is possible to further suppress the decrease in contrast and further suppress the decrease in visibility in the dark place. There is an effect.

  According to the invention which concerns on Claim 3, compared with the case where the reflecting member does not contain at least one of the phosphorescent material and the fluorescent material, it is possible to further suppress the decrease in contrast and further suppress the decrease in visibility in the dark place. There is an effect.

  According to the invention which concerns on Claim 4, compared with the case where the reflection member does not contain at least one of a luminous material and a fluorescent material, there exists an effect that display performance can be stabilized.

  According to the invention which concerns on Claim 5, compared with the case where the reflecting member does not contain at least one of the phosphorescent material and the fluorescent material, it is possible to suppress a decrease in contrast with a simple configuration and suppress a decrease in visibility in a dark place. There is an effect that can be.

  According to the invention which concerns on Claim 6, compared with the case where a reflection member does not contain at least one of a luminous material and a fluorescent material, there exists an effect that a color density can be improved.

  According to the invention concerning Claim 7, compared with the case where a reflecting member does not contain at least one of a luminous material and a fluorescent material, there exists an effect that the optical reflection characteristic by a reflecting member can be adjusted easily.

  According to the invention which concerns on Claim 8, compared with the case where a reflecting member does not contain at least one of a luminous material and a fluorescent material, the effect that the fall of contrast can be suppressed and the fall of the visibility in a dark place can be suppressed. Play.

  According to the invention which concerns on Claim 9, compared with the case where the reflecting member does not contain at least one of the phosphorescent material and the fluorescent material, it is possible to further suppress the decrease in contrast and further suppress the decrease in visibility in the dark place. There is an effect.

  According to the invention which concerns on Claim 10, compared with the case where the reflecting member does not contain at least one of the phosphorescent material and the fluorescent material, it is possible to further suppress a decrease in contrast and further suppress a decrease in visibility in a dark place. There is an effect.

  According to the eleventh aspect of the present invention, the display performance can be stabilized as compared with the case where the reflecting member does not contain at least one of the phosphorescent material and the fluorescent material.

  According to the invention which concerns on Claim 12, compared with the case where the reflecting member does not contain at least one of a phosphorescent material and a fluorescent material, it suppresses a decrease in contrast with a simple configuration and suppresses a decrease in visibility in a dark place. There is an effect that can be.

  According to the thirteenth aspect of the present invention, the color density can be improved as compared with the case where the reflecting member does not contain at least one of the phosphorescent material and the fluorescent material.

  According to the invention which concerns on Claim 14, there exists an effect that the optical reflection characteristic by a reflection member can be adjusted easily compared with the case where a reflection member does not contain at least one of a luminous material and a fluorescence material.

  Hereinafter, an embodiment of a display device and a display method of the present invention will be described with reference to the drawings.

(First embodiment)
As shown in FIG. 1, the display device 10 according to the embodiment of the present invention includes an electric field forming unit 16 that applies a voltage to the display medium 12 to form an electric field in the display medium 12, and a control unit 18. It is configured to include.

  The display medium 12 includes a front substrate 20 that serves as an image display surface, a rear substrate 22 that faces the front substrate 20 with a gap, and maintains a predetermined distance between the substrates, and between the front substrate 20 and the rear substrate 22. And a particle group 34 enclosed in each cell. Moreover, a reflecting member 28 is enclosed in each cell.

  The cell indicates a region surrounded by the front substrate 20, the back substrate 22, and the gap member 24. A dispersion medium 50 is enclosed in this cell. The particle group 34 is composed of a plurality of particles, is dispersed in the dispersion medium 50, and moves between the front substrate 20 and the rear substrate 22 in accordance with the electric field strength formed in the cell.

  In addition, the gap member 24 is provided so as to correspond to each pixel when an image is displayed on the display medium 12, and cells are formed so as to correspond to each pixel, so that the display medium 12 can display each pixel. It can be configured to be possible.

  In the present embodiment, in order to simplify the description, the present embodiment will be described using a diagram focusing on one cell.

  The surface substrate 20 has a structure in which a surface electrode 40 and a surface layer 42 are sequentially laminated on a support substrate 38. The back substrate 22 has a structure in which a back electrode 46 and a surface layer 48 are sequentially laminated on a support substrate 44.

  The front substrate 20 or both the front substrate 20 and the rear substrate 22 have translucency. Here, the translucency in the present embodiment indicates that the transmittance of visible light is 60%.

  Examples of the support substrate 38 and the support substrate 44 include glass and plastics such as polycarbonate resin, acrylic resin, polyimide resin, polyester resin, epoxy resin, and polyether sulfone resin.

  The back electrode 46 and the surface electrode 40 are made of oxides such as indium, tin, cadmium and antimon, composite oxides such as ITO, metals such as gold, silver, copper and nickel, organic materials such as polypyrrole and polythiophene, etc. can do. These can be used as a single layer film, a mixed film, or a composite film, and can be formed by vapor deposition, sputtering, coating, or the like. Moreover, the thickness is 100-2000 mm normally according to a vapor deposition method and sputtering method. The back electrode 46 and the surface electrode 40 may be formed in a desired pattern, for example, a matrix shape or a stripe shape that enables passive matrix driving, by a conventionally known means such as etching of a conventional liquid crystal display element or a printed circuit board. it can.

  Further, the surface electrode 40 may be embedded in the support substrate 38. Further, the back electrode 46 may be embedded in the support substrate 44. In this case, the material of the support substrate 38 and the support substrate 44 may affect the electrical characteristics, magnetic characteristics, and fluidity of each particle of each particle group 34. Therefore, the composition of each particle of each particle group 34, etc. Select according to.

  The back electrode 46 and the surface electrode 40 may be separated from the surface substrate 20 and the back substrate 22 and arranged outside the display medium 12.

  In the above description, the case where the electrodes (surface electrode 40 and back electrode 46) are provided on both the front substrate 20 and the back substrate 22 has been described. However, the electrodes may be provided on only one of them.

  In order to enable active matrix driving, the support substrate 38 and the support substrate 44 may include a TFT (thin film transistor) for each pixel. The TFTs are preferably formed not on the front substrate but on the rear substrate 22 because wiring lamination and component mounting are easy.

  If the display medium 12 is a simple matrix drive, the configuration of the display device 10 to be described later in detail with the display medium 12 can be simplified. If the active matrix drive using TFTs is used, the simple matrix drive is used. The display speed can be increased compared to.

  When the surface electrode 40 and the back electrode 46 are formed on the support substrate 38 and the support substrate 44, respectively, the electrodes between the electrodes that cause damage to the surface electrode 40 and the back electrode 46 and adhesion of each particle of each particle group 34 are obtained. In order to prevent the occurrence of leakage, it is preferable to form the surface layer 42 and the surface layer 48 as dielectric films on the surface electrode 40 and the back electrode 46, respectively, as necessary.

  As materials for forming the surface layer 42 and the surface layer 48, polycarbonate, polyester, polystyrene, polyimide, epoxy, polyisocyanate, polyamide, polyvinyl alcohol, polybutadiene, polymethyl methacrylate, copolymerized nylon, ultraviolet curable acrylic resin, fluorine Resin or the like can be used.

  Further, in addition to the materials described above as the material constituting the dielectric film, a material containing a charge transport material in this material can also be used.

  Examples of the charge transport material include a hydrazone compound, a stilbene compound, a pyrazoline compound, and an arylamine compound that are hole transport materials. Further, a fluorenone compound, a diphenoquinone derivative, a pyran compound, zinc oxide, or the like, which is an electron transport material, can also be used. Furthermore, a self-supporting resin having a charge transporting property can also be used.

  Specific examples thereof include polyvinyl carbazole and polycarbonate obtained by polymerization of a specific dihydroxyarylamine and bischloroformate described in US Pat. No. 4,806,443. The surface layer 42 and the surface layer 48 as dielectric films may affect the charging characteristics and fluidity of each particle group 34, and are selected according to the composition of each particle group 34 and the like. Since the surface substrate 20 constituting the display medium 12 needs to have translucency as described above, it is preferable to use a translucent material among the above materials.

  The gap member 24 for maintaining a gap between the front substrate 20 and the rear substrate 22 is formed so as not to impair the translucency of the front substrate 20, and is made of thermoplastic resin, thermosetting resin, electron beam curing. It can be formed of resin, photo-curing resin, rubber, metal or the like.

The gap member 24 may be integrated with either the front substrate 20 or the rear substrate 22. In this case, the support substrate 38 or the support substrate 44 can be manufactured by performing etching processing, laser processing processing, press processing processing, printing processing, or the like using a previously manufactured mold.
In this case, the gap member 24 can be produced on either the front substrate 20 side, the rear substrate 22 side, or both.

  The gap member 24 may be colored or colorless, but is preferably colorless and transparent so as not to adversely affect the display image displayed on the display medium 12, and in this case, for example, transparent such as polystyrene, polyester, or acrylic Resin or the like can be used.

  The particulate gap member 24 is also preferably transparent, and glass particles can be used in addition to transparent resin particles such as polystyrene, polyester or acrylic.

  Note that “transparent” means having a transmittance of 50% or more with respect to visible light.

The dispersion medium 50 in which each particle group 34 is dispersed is preferably an insulating liquid. Here, “insulating” indicates that the volume resistivity is 10 ⁷ Ω · cm or more.

  Specific examples of the insulating liquid include hexane, cyclohexane, toluene, xylene, decane, hexadecane, kerosene, paraffin, isoparaffin, silicone oil, modified silicone oil, dichloroethylene, trichloroethylene, perchloroethylene, high-purity petroleum, ethylene glycol, Alcohols, ethers, esters, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, 2-pyrrolidone, N-methylformamide, acetonitrile, tetrahydrofuran, propylene carbonate, ethylene carbonate, benzine, diisopropylnaphthalene, olive oil, isopropanol , Trichlorotrifluoroethane, tetrachloroethane, dibromotetrafluoroethane, etc. Mixtures thereof can be preferably used.

Moreover, water (so-called pure water) can also be suitably used as the dispersion medium 50 by removing impurities so that the following volume resistance value is obtained. The volume resistance value is preferably 10 ³ Ωcm or more, more preferably 10 ⁷ Ωcm to 10 ¹⁹ Ωcm, and even more preferably 10 ¹⁰ Ωcm to ^{10 19} Ωcm. By setting the volume resistance value in this range, it is possible to more effectively apply an electric field to the particle group, and the generation of bubbles due to the electrolysis of the liquid due to the electrode reaction is suppressed, The electrophoretic properties of the particles are not impaired, and excellent repeated stability can be imparted.

  The insulating liquid can be added with an acid, alkali, salt, dispersion stabilizer, stabilizer for the purpose of anti-oxidation or UV absorption, antibacterial agent, preservative, etc., if necessary. It is preferable to add so that it may become the range of the specific volume resistance value shown above.

  For insulating liquids, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorosurfactants, silicone surfactants, metal soaps as charge control agents , Alkyl phosphate esters, succinimides and the like can be added.

  More specific examples of the ionic and nonionic surfactants are as follows. Nonionic activators include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, And fatty acid alkylolamide. Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonic acid of higher fatty acid ester, and the like. Examples of the cationic surfactant include primary to tertiary amine salts and quaternary ammonium salts. These charge control agents are preferably 0.01% by weight or more and 20% by weight or less, particularly preferably 0.05 to 10% by weight, based on the solid content of the particles. If the amount is less than 0.01% by weight, the desired charge control effect is insufficient, and if it exceeds 20% by weight, the conductivity of the developer increases excessively, making it difficult to use.

  The particle group 34 enclosed in the display medium 12 is also preferably dispersed in a polymer resin as the dispersion medium 50. The polymer resin is preferably a polymer gel, a polymer polymer or the like.

  As this polymer resin, agarose, agaropectin, amylose, sodium alginate, propylene glycol ester of alginate, isolikenan, insulin, ethylcellulose, ethylhydroxyethylcellulose, curdlan, casein, carrageenan, carboxymethylcellulose, carboxymethyl starch, callose, agar, chitin , Chitosan, silk fibroin, gar gum, quince seed, crown gall polysaccharide, glycogen, glucomannan, keratan sulfate, keratin protein, collagen, cellulose acetate, gellan gum, schizophyllan, gelatin, elephant palm mannan, tunisin, dextran, dermatan sulfate, starch , Tragacanth gum, nigeran, hyaluronic acid, hydroxyethyl cellulose, hydroxy In addition to polymer gels derived from natural polymers such as propylcellulose, pustulan, funolan, decomposed xyloglucan, pectin, porphyran, methylcellulose, methyl starch, laminaran, lichenan, lentinan, locust bean gum, etc. Includes almost all polymer gels.

  In addition, polymers containing functional groups of alcohol, ketone, ether, ester, and amide in the repeating unit are exemplified. For example, polyvinyl alcohol, poly (meth) acrylamide and derivatives thereof, polyvinyl pyrrolidone, polyethylene oxide, and the like. Mention may be made of copolymers containing molecules.

  Among these, gelatin, polyvinyl alcohol, poly (meth) acrylamide and the like are preferably used from the viewpoints of production stability, electrophoretic characteristics and the like.

  These polymer resins are preferably used as the dispersion medium 50 together with the insulating liquid.

  The particle group 34 enclosed in each cell is composed of a plurality of particles, and is dispersed in the dispersion medium 50, and according to the electric field strength formed in the cell, the surface substrate 20 and the back substrate 22 Move between different substrates.

  Each particle of the particle group 34 includes glass beads, insulating metal oxide particles such as alumina, titanium oxide, and the like, thermoplastic or thermosetting resin particles, and a colorant fixed on the surface of these resin particles. And particles containing an insulating colorant in a thermoplastic or thermosetting resin, and metal colloid particles having a plasmon coloring function.

  Examples of the thermoplastic resin used in the production of particles include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyls such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate. Α-methylene aliphatic monocarboxylic acid such as ester, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers or copolymers of vinyl ethers such as acid esters, vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone It can be exemplified.

  In addition, as thermosetting resins used for the production of particles, crosslinked resins mainly composed of divinylbenzene and crosslinked resins such as crosslinked polymethyl methacrylate, phenol resins, urea resins, melamine resins, polyester resins, silicones Examples thereof include resins. Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include a polymer, polyethylene, polypropylene, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, and paraffin wax.

  As the colorant, organic or inorganic pigments, oil-soluble dyes, etc. can be used, magnetic powders such as magnetite and ferrite, carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan colorant, Known colorants such as an azo yellow color material, an azo magenta color material, a quinacridone magenta color material, a red color material, a green color material, and a blue color material can be given. Specifically, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. Blue 15: 1, C.I. I. Pigment Blue 15: 3, etc. can be exemplified as typical ones.

  The particle resin may be mixed with a charge control agent, if necessary. As the charge control agent, known materials used for toner materials for electrophotography can be used. For example, cetylpyridyl chloride, BONTRON P-51, BONTRON P-53, BONTRON E-84, BONTRON E-81 (above, Quaternary ammonium salts such as Orient Chemical Industry Co., Ltd., salicylic acid metal complexes, phenol condensates, tetraphenyl compounds, metal oxide particles, and metal oxide particles surface-treated with various coupling agents. .

A magnetic material may be mixed in the inside or the surface of the particles as necessary. As the magnetic material, a color-coated inorganic magnetic material or organic magnetic material is used as necessary. Further, a transparent magnetic material, in particular, a transparent organic magnetic material does not hinder the color development of the color pigment, and the specific gravity is smaller than that of the inorganic magnetic material, and is more desirable.
As the colored magnetic powder, for example, a small-diameter colored magnetic powder described in JP-A-2003-131420 can be used. A material provided with magnetic particles serving as nuclei and a colored layer laminated on the surface of the magnetic particles is used. The colored layer may be selected such that the magnetic powder is opaquely colored with a pigment or the like, but it is preferable to use, for example, a light interference thin film. This optical interference thin film is a thin film having a thickness equivalent to the wavelength of light made of an achromatic material such as SiO ₂ or TiO ₂ , and reflects light in a wavelength selective manner by optical interference in the thin film. is there.

  An external additive may be attached to the surface of the particles as necessary. The color of the external additive is preferably transparent so as not to affect the color of the particles.

  As the external additive, inorganic particles such as metal oxides such as silicon oxide (silica), titanium oxide, and alumina are used. In order to adjust the charging property, fluidity, and environment dependency of the particles, they can be surface-treated with a coupling agent or silicone oil.

  Coupling agents include positively chargeable ones such as aminosilane coupling agents, aminotitanium coupling agents, nitrile coupling agents, and silanes that do not contain nitrogen atoms (consisting of atoms other than nitrogen). There are negatively charged ones such as coupling agents, titanium-based coupling agents, epoxy silane coupling agents, and acrylic silane coupling agents. Silicone oil includes positively charged ones such as amino-modified silicone oil, dimethyl silicone oil, alkyl-modified silicone oil, α-methylsulfone-modified silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone. Examples include negatively chargeable oils. These are selected according to the desired resistance of the external additive.

Of the above external additives, well-known hydrophobic silica and hydrophobic titanium oxide are preferable. In particular, the reaction of TiO (OH) ₂ described in JP-A-10-3177 with a silane compound such as a silane coupling agent. The titanium compound obtained in (1) is preferred. As the silane compound, any of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. This titanium compound is produced by reacting TiO (OH) ₂ produced in a wet process with a silane compound or silicone oil and drying it. Since it does not pass through the firing step of several hundred degrees, a strong bond between Ti is not formed, there is no aggregation, and the particles are in the state of primary particles. Furthermore, since the silane compound or silicone oil reacts directly with TiO (OH) ₂ , the amount of silane compound or silicone oil treated can be increased, and the charging characteristics can be controlled by adjusting the amount of silane compound treated. The charging ability that can be imparted and can be imparted can be significantly improved over that of conventional titanium oxide.

  The volume average primary particle size of the external additive is generally 5 to 100 nm and is preferably 10 to 50 nm, but is not limited thereto.

  The mixing ratio of the external additive and the particles is adjusted based on the balance between the particle size of the particles and the particle size of the external additive. If the amount of the external additive added is too large, a part of the external additive is liberated from the particle surface and adheres to the surface of the other particle, so that desired charging characteristics cannot be obtained. In general, the amount of the external additive is preferably 0.01 to 3 parts by weight and more preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the particles.

  The external additive may be added to any one of a plurality of types of particles, or may be added to a plurality of types or all types of particles. When an external additive is added to the surface of all particles, it is desirable that the external additive is applied to the particle surface with impact force or the particle surface is heated to firmly fix the external additive to the particle surface. . As a result, the external additive is released from the particles, and the external additive of different polarity is strongly aggregated to prevent the formation of an aggregate of the external additive that is difficult to dissociate with an electric field. Is prevented.

  In the present embodiment, in the particle group 34, in order to move between the front substrate 20 and the rear substrate 22 in accordance with the electric field formed between the substrates, the particle group 34 previously corresponds to an electric field such as an average charge amount or an electrostatic amount. It is assumed that the characteristics that contribute to the movement are adjusted in advance.

  Specifically, the adjustment of the average charge amount of each particle constituting the particle group 34 is specifically performed by adjusting the kind and amount of the charge control agent blended in the resin, the kind and amount of the polymer chain bonded to the particle surface, and the particle. Types and amounts of external additives added or embedded on the surface, types and amounts of surfactants, polymer chains and coupling agents applied to the particle surface, specific surface area of the particles (volume average primary particle size and particle shape) This is possible by adjusting the coefficient.

Moreover, the adjustment of the magnetic amount of each particle can be specifically performed by using various methods for imparting magnetism to the particle.
For example, like conventional electrophotographic magnetic toner, a magnetic material such as powdered magnetite is mixed with a resin to create particles, or a magnetic material and a monomer are dispersed and polymerized to create particles. be able to. Further, the magnetic material is deposited in the pores of the porous particles. Or the method of coat | covering a magnetic body is also known. For example, particles are created by polymerizing active sites on the surface of the magnetic material and wrapping the magnetic material with resin, or by depositing resin dissolved on the surface of the magnetic material and creating particles wrapping the magnetic material with resin. Or A light, transparent or colored organic magnetic material can also be used as the magnetic material. The amount of magnetic particles can be adjusted by adjusting the type and amount of magnetic material used.

  As a method for producing the particle group 34, any conventionally known method may be used. For example, as described in JP-A-7-325434, a resin, a pigment, and a charge control agent are weighed so as to have a predetermined mixing ratio, and after the resin is heated and melted, the pigment is added, mixed, dispersed, and cooled. Then, a method of preparing particles using a pulverizer such as a jet mill, a hammer mill, a turbo mill, etc., and then dispersing the obtained particles in a dispersion medium can be used. Also, particles containing a charge control agent are prepared by polymerization methods such as suspension polymerization, emulsion polymerization, dispersion polymerization, coacervation, melt dispersion, emulsion aggregation, and then dispersed in a dispersion medium. A particle dispersion medium may be prepared. Further, the resin can be plasticized, the dispersion medium does not boil, and the resin, the colorant, the charge control agent, and the dispersion medium are at a temperature lower than the decomposition point of the resin, the charge control agent and / or the colorant. There are methods using suitable equipment that can disperse and knead the raw materials. Specifically, the pigment, the resin, and the charge control agent are heated and melted in a dispersion medium with a meteor mixer, a kneader, etc., and the molten mixture is cooled with stirring using the temperature dependence of the solvent solubility of the resin. The particles can be made by solidification / precipitation.

  Furthermore, the above raw materials are put into a suitable container equipped with granular media for dispersion and kneading, for example, a heated vibration mill such as an attritor or a heated ball mill, and the container is placed in a preferred temperature range, for example, 80 A method of dispersing and kneading at ˜160 ° C. can be used. As granular media, steels such as stainless steel and carbon steel, alumina, zirconia, silica and the like are preferably used. In order to produce particles by this method, the raw material that has been previously fluidized is further dispersed in a container using granular media, and then the dispersion medium is cooled to precipitate a resin containing a colorant from the dispersion medium. The granular media generates a shear and / or impact to reduce the particle size while maintaining a motion state during and after cooling.

  The content (% by mass) of the particle group 34 with respect to the total mass in the cell is not particularly limited as long as the desired hue can be obtained, and the cell thickness (that is, the front substrate 20 and the rear substrate). It is effective for the display medium 12 to adjust the content according to the distance between the substrates). That is, in order to obtain a desired hue, the content decreases as the cell becomes thicker, and the content can increase as the cell becomes thinner. Generally, it is 0.01-50 mass%.

  The size of the cell in the display medium 12 is closely related to the resolution of the display medium 12, and the display medium 12 capable of displaying a high-resolution image as the cell is smaller can be manufactured. The length of the twelve surface substrates 20 in the plate surface direction is about 10 μm to 1 mm.

  In the display medium 12 according to the present embodiment, a reflecting member 28 is enclosed in a cell formed between the front substrate 20 and the rear substrate 22 constituting the display medium 12.

  The reflecting member 28 has an optical reflection characteristic different from that of the particles constituting the particle group 34, and a void (that is, a through hole) through which each particle constituting the particle group 34 passes (can pass through). ) And at least one of a phosphorescent material and a fluorescent material.

  Here, “having optical reflection characteristics different from the particles constituting the particle group 34” means that the dispersion medium 50 in which only the particle group 34 is dispersed and the reflecting member 28 are compared and visually observed. Furthermore, it means that there is a difference that can distinguish the difference between the two in chromaticity, lightness, and saturation. In addition, it is preferable that chromaticity differs among these chromaticity, lightness, and saturation.

  For example, when the chromaticity is different, the “discernable difference” specifically means that the CIELAB value in each of the dispersion medium 50 in which only the particle group 34 is dispersed and the reflection member 28 is X. This shows that the difference between a * and b * when measured with X-Rite404 manufactured by -Rite is 5 or more.

  Since the reflecting member 28 of the present invention contains at least one of a phosphorescent material and a fluorescent material, it becomes possible to improve the visibility in weak illumination light or in the dark.

  As shown in FIG. 1, the reflection member 28 is disposed so as to exist over the entire surface of the front substrate 20 between the front substrate 20 and the rear substrate 22.

  In the present embodiment, the arrangement of the reflecting members 28 in the cell thickness direction (position between the front substrate 20 and the rear substrate 22 in the stacking direction of these substrates) is the front substrate 20 and the rear substrate 22. In this case, the color and image displayed on the display medium as shown in the display medium 13 shown in FIG. It is better from the viewpoint of reducing the viewing angle dependency to dispose the reflecting member 28 so that it is positioned on the side to be visually recognized. The configuration of the display medium 13 is the same except that the arrangement positions of the display medium 12 and the reflection member 28 are different, and thus detailed description thereof is omitted.

The shape of the reflecting member 28 is not particularly limited as long as it includes a void (that is, a through-hole) through which each particle constituting the particle group 34 can pass, and an aggregate of a plurality of particles or a film It can comprise as a shaped member. Note that the reflecting member 28 is preferably configured as an aggregate of a plurality of particles among these shapes.
This is because the reflective member 28 configured as an aggregate of particles can easily increase the color density due to the reflective member 28 itself by increasing the filling rate of the particles into the cell, and the high density in the display medium 12. This is because contrast can be obtained.

  In the present embodiment, the case where the reflecting member 28 is configured as an aggregate of large-diameter particles 26 will be described.

  When the reflecting member 28 is configured as an aggregate of a plurality of particles, as shown in FIG. 1, the reflecting member 28 is composed of a plurality of particles having a volume average primary particle size larger than each particle constituting the particle group 34 (hereinafter referred to as “particles”). (Referred to as large-diameter particles).

  The large-diameter particles 26 are arranged in the cell with a gap through which each particle of the particle group 34 can pass. For this reason, each particle constituting the particle group 34 moves between the front substrate 20 and the rear substrate 22 through a gap formed by a plurality of large-diameter particles 26.

In the present embodiment, the reflecting member 28 is provided with a plurality of large-diameter particles 26 arranged in a line in a direction orthogonal to the stacking direction of the front substrate 20 and the rear substrate 22.
A case will be described in which the plurality of large-diameter particles 26 constituting the reflecting member 28 of the present embodiment are arranged in a line in a direction perpendicular to the stacking direction of the front substrate 20 and the rear substrate 22. However, the present invention is not limited to this configuration, and may be arranged in a plurality of rows as shown in the display medium 14 of FIG. The configuration of the display medium 14 is the same except that the configuration of the display medium 12 and the reflecting member 28 is the same except that the large-diameter particles 26 are arranged in a plurality of rows.

  The large-diameter particles 26 must have a volume average primary particle size that is 10 times or more larger than the respective particles constituting the particle group 34 because each particle of the particle group 34 needs to be movable through the inter-particle gap. Is preferably applied, and more preferably 20 times or more. However, since the large-diameter particles 26 are sealed between the substrates, the particle size is smaller than the distance between the substrates.

  Here, when the diameter of the particle group 34 is uniform, the size of the large diameter particle 26 may be 10 times larger than the particle of the particle group 34. When there is a variation, the particles constituting the particle group 34 are not clogged between the large-diameter particles 26 and the display performance is stabilized when the size is 20 times or more.

  If the particle diameter of the large particle 26 is too small, there may be a case where it is not possible to secure a particle gap in which the particles constituting the particle group 34 can move. If the particle diameter is too large, the substrate gap becomes large, resulting in high voltage and low display speed. Sometimes. When the volume average primary particle size of the large-diameter particles 26 is about 10 μm, the particles in the particle group 34 having a volume average primary particle size of several tens of nanometers can move through the gap between the large-diameter particles 26.

Next, the material which comprises the reflection member 28 is demonstrated.
The reflection member 28 includes at least a resin, at least one of a phosphorescent material and a fluorescent material, and a colorant. The reflection member 28 may include a charge control agent as necessary, and the color material may also serve as the charge control agent.

Specifically, as shown in FIG. 2, each of the plurality of large-diameter particles 26 constituting the reflecting member 28 is referred to as a resin 27 and a light emitting material (in the case where a fluorescent material and a phosphorescent material are collectively referred to) 30) and a color material 32.
Hereinafter, each material which comprises the reflection member 28 is demonstrated.

--- Phosphorescent material-
In the present invention, a phosphorescent material refers to a substance that internally accumulates electric light, daylight sunlight, etc., and can emit light in the dark, and can be used by mixing it with various resins. It is a material that can be repeated.

This phosphorescent material includes zinc sulfide (ZnS), zinc silicate (Zn ₂ SiO4), zinc cadmium sulfide [(Zn, Cd) S], calcium sulfide (CaS), strontium sulfide (SrS), calcium tungstate (CaWO4). ), Inorganic pigments such as strontium aluminate (SrAl2O4), phosphorescent zinc sulfide, and zinc hexasulfide, and organic pigments such as Lumogen L Yellow, Lumogen Yellow Orange, and Lumogen L Red Orange. It is also possible to add rare earth elements, particularly Eu and Dy, to the inorganic pigment.

―Fluorescent material―
As the fluorescent material, either an inorganic fluorescent material or an organic fluorescent material may be used. Inorganic fluorescent materials include Ca, Ba, Mg, Zn, Cd and other oxides, sulfides, silicates, phosphates, tungstates and other crystals as the main component, Mn, Zn, Ag, Cu, Examples include those obtained by adding a metal element such as Sb or Pb or a rare earth element such as a lanthanoid as an activator and firing. Examples of organic fluorescent materials include fluorescent brighteners, diaminostilbenes, imidazoles, coumarins, triazoles, carbazoles, pyridines, naphthalic acid or imidazolone derivatives, fluorescein, mineral oil, thioflavine, eosin, todamine, anthracene, terphenyl, Brilliant sulfotrabin, basic yellow, oleene, organic pigments (trade name: Lumorgen Color (BASF), FZ6014 (Shinloihi)), and the like.

The phosphorescent material and the fluorescent material are preferably in the form of particles.
When the phosphorescent material is particulate, the volume average primary particle diameter of the phosphorescent material is preferably 10 μm or less and 0.01 μm or more, and more preferably 3 μm or less. Further, in order to effectively absorb (store) light, the volume average primary particle diameter of the phosphorescent material is preferably 0.1 μm or more.
When the fluorescent material is in the form of particles, the volume average primary particle diameter of the fluorescent material is preferably 10 μm or less and 0.01 μm or more, and more preferably 3 μm or less. In order to effectively emit light, the fluorescent material preferably has a volume average primary particle diameter of 0.1 μm or more.

  Each of the phosphorescent material and the fluorescent material is preferably subjected to a surface treatment with a surface treatment agent for the purpose of improving dispersibility of the phosphorescent material and the fluorescent material in a resin.

  As the surface treatment agent, known surface treatment agents such as various coupling agents or dispersibility improvers can be used. Specific examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminate coupling agents, zirconate coupling agents, and the like.

  By using the surface-treated fluorescent material and phosphorescent material, it becomes possible to uniformly disperse the phosphor material or phosphorescent material in the display device particles. As a result, the luminous efficiency of the phosphorescent material can be improved, or The emission intensity can be improved.

  In the present invention, metal particles such as copper and bismuth can be added as an auxiliary agent in order to promote light emission of the phosphorescent material and the fluorescent material.

The addition amount of the fluorescent material according to the present invention is preferably 5 to 40% by mass, particularly 10 to 20% by mass with respect to the entire material constituting the reflecting member 28 for reasons of visibility in the dark. When there is more addition amount than 40 mass%, the color (for example, white) of the reflective member itself in a bright place will fall.
Moreover, the addition amount of the phosphorescent material according to the present invention is preferably 5 to 40% by mass, and particularly preferably 10 to 20% by mass with respect to the whole for reasons of visibility in a dark place. When there is more addition amount than 40 mass%, the color (for example, white) of the reflective member itself in a bright place will fall.
Further, when both the fluorescent material and the phosphorescent material are included in the reflecting member 28, the total amount of the fluorescent material and the phosphorescent material added is 5 to 40 with respect to the whole for reasons of visibility in a dark place. The mass% is good, especially 10 to 20 mass%. When there is more addition amount than 40 mass%, the color (for example, white) of the reflective member itself in a bright place will fall.

-Color material-
Examples of the color material contained in the reflecting member 28 include organic and inorganic dye / pigment black materials such as carbon black, titanium black, magnetic powder, and oil black as black color materials.

  Examples of white color materials include titanium oxides such as rutile titanium oxide and anatase titanium oxide, and white pigments such as zinc white, lead white, zinc sulfide, aluminum oxide, silicon oxide, and zirconium oxide.

  As the chromatic color material, phthalocyanine-based, quinacridone-based, azo-based, condensed-based, insoluble lake pigments, and inorganic oxide-based dyes can be used. Specific examples thereof include aniline blue, calcoyl blue, chrome yellow, ultramarine blue, deyupon oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. Blue 15: 1, C.I. I. Pigment Blue 15: 3, etc. can be exemplified as typical ones.

  The phosphorescent substance and the fluorescent substance contained in the reflecting member 28 may be used as a color material or may be used in combination with the color material. As a color material used in combination with at least one of a phosphorescent substance and a fluorescent substance, titanium oxide is preferable. Among the titanium oxides, rutile type titanium oxide is desirable as the titanium oxide used in combination.

  The white reflecting member 28 can be formed by using at least one of the phosphorescent material and the fluorescent material in combination with titanium oxide.

  Here, as the titanium oxide used in combination with the phosphorescent material and the fluorescent material, at least two types having different average particle diameters are preferably used in combination.

Conventionally, titanium oxide has poor dispersibility, and even if the dispersion is increased, titanium oxide with a large particle size has a high specific gravity, so secondary and tertiary agglomeration occurs quickly, and dispersion stability is poor. There was a problem that it could not be demonstrated. On the other hand, titanium oxide having a small particle diameter has a drawback that it cannot sufficiently scatter light and has a low hiding power.
However, by using at least two types of titanium oxides having different average particle sizes in combination, it is possible to improve both dispersion stability and concealment.
As for the volume average primary particle diameter of titanium oxide that can be used, at least one kind is preferably 0.1 μm to 1.0 μm, which is an optically high particle concealing particle diameter. The volume average primary particle size of other titanium oxides is preferably less than 0.1 μm.

  Further, the titanium oxide may be subjected to a surface treatment. As the surface treatment agent, various coupling agents and organic substances dissolved in a solvent can be used as long as the whiteness is not affected.

  Examples of the structure of the color material when the color material also serves as a charge control agent include those having an electron withdrawing group or electron donating group, a metal complex, and the like. Specific examples of the coloring material that also serves as the charge control agent include C.I. I. Pigment violet 1, C.I. I. Pigment violet 3, C.I. I. Pigment violet 23, C.I. I. Pigment black 1 and the like.

  The addition amount of the color material is preferably in the range of 1 to 60% by mass and more preferably in the range of 5 to 50% by mass with respect to the entire particles for display device when the specific gravity of the color material is 1. preferable.

-Resin-
Examples of the resin constituting the large particle 26 of the reflecting member 28 include polyolefin resins, polystyrene, acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, vinyl chloride, polyvinyl butyral, and other polyvinyl resins; vinyl chloride-vinyl acetate copolymer Styrene-acrylic acid copolymer; straight silicone resin composed of an organosiloxane bond and its modification; fluorine resin such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride; polyester, polyurethane, polycarbonate; amino resin; An epoxy resin etc. are mentioned.

  These may be used alone or in combination with a plurality of resins. These resins may be cross-linked.

  Further, as the resin used for the reflecting member 28, a known binder resin known as a main component for toner used in conventional electrophotography can be used without any problem. In particular, it is preferable to use a resin containing a crosslinking component.

-Charge control agent-
If necessary, a charge control agent may be added to the reflecting member 28 in order to control chargeability.

  As the charge control agent, known ones used for toner materials for electrophotography can be used, for example, quaternary ammonium salts such as cetylpyridyl chloride, P-51, P-53 (manufactured by Orient Chemical Industries), Examples thereof include salicylic acid-based metal complexes, phenol-based condensates, tetraphenyl compounds, metal oxide particles, or metal oxide particles surface-treated with various coupling agents.

  The addition amount of the charge control agent is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass with respect to the entire reflection member.

  As the size of the dispersion unit in the large particle 26 of the charge control agent, a volume average particle size of 5 μm or less is used, and 1 μm or less is preferable.

  This charge control agent may be present in a compatible state in the large particle 26.

  The charge control agent is desirably colorless, has a low coloring power, or has a color similar to the color of the entire large particle 26. By using a charge control agent that is colorless, has a low coloring power, or a color similar to the color of the entire large-diameter particle 26, the impact on the hue of the display device particles can be reduced.

  Here, “colorless” means having no color, and “low coloring power” means that the influence on the color of the entire display device particle contained is small. In addition, “the same color as the color of the entire large-diameter particle 26” means that the charge control agent itself has a hue but is the same color as or similar to the color of the entire large-diameter particle 26 included, and as a result, included This means that the influence on the color of the entire large-diameter particle 26 is small. For example, in the large-diameter particle 26 containing a white pigment as a color material, the white charge control agent is included in the category of “same color as the color of the entire contained particle”.

  In any case, as the color of the charge control agent, regardless of “colorless”, “low coloring power”, or “similar to the color of the whole contained particles”, the color of the large-diameter particles 26 containing them is desired. Any color can be used.

The volume average primary particle size of the large particle 26 cannot be generally specified, but in order to obtain a good image, the volume average particle size is preferably 1 to 30 μm, more preferably 2 to 20 μm, particularly 2 ˜15 μm is preferred.
Further, the particle size distribution of the particles is preferably sharp and is preferably monodispersed.

  In the present embodiment, when the particle diameter to be measured is 2 μm or more, a Coulter counter TA-II type (manufactured by Beckman-Coulter) is used as the measuring device, and the electrolyte is ISOTON-II (manufactured by Beckman-Coulter). ) Was used to measure the particle size.

  As a measurement method, 0.5 to 50 mg of a measurement sample was added to 2 ml of a 5% aqueous solution of a surfactant as a dispersant, more preferably sodium alkylbenzenesulfonate, and this was added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute, and the particle size is 2.0 to 60 μm using the Coulter counter TA-II type with an aperture having an aperture diameter of 100 μm. The particle size distribution of particles in the range was measured. The number of particles to be measured was 50,000.

  For the divided particle size range (channel), the measured particle size distribution is drawn from the small diameter side for each volume and number, and the particle size that is 16% cumulative by volume is accumulated by volume average particle size D16v and number. The cumulative number particle diameter of 16% is defined as D16p. Similarly, a particle diameter that is 50% cumulative in volume is defined as a volume average particle diameter D50v, and a particle diameter that is cumulative 50% in number is defined as a number average particle diameter D50p. Similarly, a particle diameter that is 84% cumulative in volume is defined as a volume average particle diameter D84v, and a cumulative particle diameter that is 84% cumulative in number is defined as D84p. The volume average particle diameter is the D50v.

Using these, the volume average particle size distribution index (GSDv) is calculated from (D84v / D16v) ^1/2 , the number average particle size index (GSDp) is calculated from (D84p / D16p) ^1/2 , and the small diameter side number average The particle size index (lower GSDp) is calculated by {(D50p) / (D16p)}.

  On the other hand, when the particle diameter to be measured was less than 2 μm, the particle size was measured using a laser diffraction particle size distribution analyzer (LA-700: manufactured by Horiba, Ltd.). As a measuring method, the sample in the state of dispersion is adjusted to 2 g in solid content, and ion exchange water is added thereto to make 40 ml. This is put into the cell until an appropriate concentration is reached, and after 2 minutes, the concentration is measured when the concentration in the cell becomes stable. The obtained volume average particle diameter for each channel was accumulated from the smaller volume average particle diameter, and the volume average particle diameter was determined to be 50%.

  When measuring powders such as external additives, 2 g of a measurement sample is added to a surfactant, more preferably 50 ml of a 5% aqueous solution of sodium alkylbenzenesulfonate, and an ultrasonic disperser (1,000 Hz) is used. A sample was prepared by dispersing for 2 minutes and measured by the same method as the above dispersion.

-Method for producing large-diameter particles 26 constituting the reflecting member 28-
As a method for producing the large particle 26, suspension polymerization, emulsion polymerization, dispersion polymerization using at least one of a phosphorescent material and a fluorescent material, a coloring material, a monomer as a raw material of a resin, and a charge control agent as necessary For example, spherical particles produced by a wet production method, amorphous particles produced by a conventional pulverization classification method, or those that have been heat-treated in order to make the shape of these particles uniform are preferable. This particle size distribution can be adjusted by classification operation.

  Examples include, but are not limited to, various vibrating sieves, ultrasonic sieves, pneumatic sieves, and wet sieves, rotor rotary classifiers using the principle of centrifugal force, and wind classifiers. . These can be adjusted to a desired particle size distribution singly or in combination. In particular, when adjusting precisely, it is preferable to use a wet sieve.

  Further, as a method for controlling the particle shape (a method for controlling the shape factor), the following method and the like can be suitably exemplified. For example, in a so-called suspension polymerization method in which a polymer is dissolved in a solvent described in JP-A-10-10775, a colorant is mixed, and dispersed in an aqueous medium in the presence of an inorganic dispersant to form particles. Add a non-polymerizable organic solvent that is compatible with (or less compatible with the solvent), perform suspension polymerization, create particles, remove, and dry in a process of removing the organic solvent. A method for selecting the method is preferably exemplified. As this drying method, a lyophilization method is preferably exemplified. In this lyophilization method, it is preferable to carry out in the range of −10 ° C. to −200 ° C. (more preferably, −30 ° C. to −180 ° C.). In addition, the freeze-drying method is performed at a pressure of about 40 Pa or less, but is particularly preferably performed at 13 Pa or less. Here, as an organic solvent, ester solvents such as methyl acetate and propyl acetate, ether solvents such as diethyl ether, ketone solvents such as methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone, hydrocarbon solvents such as toluene and cyclohexane Examples of the solvent include halogenated hydrocarbon solvents such as dichloromethane, chloroform, and trichloroethylene. These solvents are preferably capable of dissolving the polymer, and those having a solubility in water of about 0 to 30% by mass are preferable. In addition, cyclohexane is particularly preferable in view of safety, cost, and productivity in industrialization.

  Further, the method of agglomerating and coalescing small particles described in JP-A-2000-292971, increasing the particle size to a desired particle diameter, and mechanically applying to particles obtained by conventionally known melt-kneading, pulverization, classification methods, etc. The particle shape can also be controlled by a method of applying a strong impact force (for example, a hybridizer (Nara Machinery Co., Ltd.), an ang mill (Hosokawa Micron), a θ composer (Tokuju Kosakusho), etc.) or a heating method.

  In order to enclose the produced large-diameter particles 26 between the front substrate 20 and the rear substrate 22, for example, an electrophotographic method or a toner jet method is used. Further, when immobilizing the large-diameter particles 26, for example, after encapsulating the large-diameter particles 26, heating (and pressurizing if necessary) to dissolve the particle group surface layer of the large-diameter particles 26. , While maintaining the particle gap.

  The volume filling rate in each cell of the reflecting member 28 configured as an aggregate of the large-diameter particles 26 is preferably 10 to 95 vol% for the reason of the color of the reflecting member, for example, whiteness, and 20 to 20%. It is more preferable that it is 90 vol%, and it is especially preferable that it is 30-90 vol%.

  The display medium 12 having the above configuration is a bulletin board capable of storing and rewriting images, a circulation version, an electronic blackboard, an advertisement, a signboard, a flashing sign, an electronic paper, an electronic newspaper, an electronic book, and a document sheet that can be shared with a copier / printer Can be used for etc.

  As described above, the display device 10 according to the embodiment of the present invention forms an electric field between the front substrate 20 and the rear substrate 22 of the display medium 12 by applying a voltage to the display medium 12. The electric field forming section 16 and the control section 18 are configured (see FIG. 1). The electric field forming unit 16 is connected to the control unit 18 so as to be able to exchange signals.

  The display medium 12 corresponds to the display medium of the present invention, the display device 10 corresponds to the display device of the present invention, and the electric field forming unit 16 corresponds to the electric field forming means of the display device of the present invention.

The electric field forming unit 16 is electrically connected to the front electrode 40 and the back electrode 46.
In the present embodiment, the case where both the front electrode 40 and the back electrode 46 are electrically connected to the electric field forming unit 16 will be described. However, one of the front electrode 40 and the back electrode 46 is grounded. The other may be connected to the electric field forming unit 16.

  The display device 10 is provided with a mounting portion (not shown) for mounting the display medium 12. When the display medium 12 is attached to this attachment portion (not shown), the front electrode 40 and the back electrode 46 are connected to the electric field forming portion 16 of the display device 10 so as to be able to exchange signals.

  The control unit 18 stores in advance various programs including a CPU (Central Processing Unit) that controls the operation of the entire apparatus, a RAM (Random Access Memory) that temporarily stores various data, and a control program that controls the entire apparatus. And a ROM including a read only memory (ROM).

  The electric field forming unit 16 is a voltage applying device for applying a voltage to the surface electrode 40 and the back electrode 46, and applies a voltage according to the control of the control unit 18 between the surface electrode 40 and the back electrode 46.

  When the display medium 12 is mounted on a mounting unit (not shown) of the display device 10 and a voltage is applied from the electric field forming unit 16 to the front electrode 40 and the back electrode 46 of the display medium 12 under the control of the control unit 18. An electric field corresponding to the applied voltage is formed in the dispersion medium 50.

  Due to the formed electric field, the particle group 34 moves between the front substrate 20 and the rear substrate 22. For example, when the particles constituting the particle group 34 are charged to the negative electrode, and the positive electrode voltage is applied to the front electrode 40 and the negative electrode voltage is applied to the back electrode 46, the particles constituting the particle group 34 are reflected by the reflecting member 28. And move from the back substrate 22 side to the front substrate 20 side (see FIG. 6). At this time, when visually recognized from the front substrate 20 side, the color of the particles of the particle group 34 located on the front substrate 20 side is visually recognized as the color of the display medium 12.

  On the other hand, when a negative electrode voltage is applied to the front electrode 40 and a positive electrode voltage is applied to the back electrode 46, the particles constituting the particle group 34 pass through the gaps in the reflecting member 28 and pass from the front substrate 20 side to the back substrate 22 side. (See FIG. 1). At this time, when viewed from the front substrate 20 side, the color of the reflecting member 28 is viewed as the color of the display medium 12.

  Here, since the reflecting member 28 contains at least one of a fluorescent material and a phosphorescent material, it is included in the reflecting member 28 even when the display medium 12 is placed in a dark environment without external light. By virtue of at least one of the fluorescent material and the phosphorescent material, a reduction in visibility in the dark place of the display medium 12 can be suppressed as compared with the case where this configuration is not used.

(Second Embodiment)
Although the case where the reflecting member 28 is an aggregate of a plurality of large-diameter particles 26 has been described in the above embodiment, the case where the reflecting member 28 is configured as a porous member will be described in the present embodiment.

  The display medium 17 according to the present embodiment is configured as a porous member in place of the reflecting member 28 configured by the aggregate of large-diameter particles 26 provided in the display medium 12 described in the above embodiment. A reflection member 29 is provided.

  That is, the display medium 17 according to the present embodiment includes a front substrate 20 that serves as an image display surface, a rear substrate 22 that faces the front substrate 20 with a gap, and maintains a predetermined distance between these substrates. It is configured to include a gap member 24 that partitions the back substrate 22 and the substrate into a plurality of cells, and a particle group 34 enclosed in each cell, and in the cell between the front substrate 20 and the back substrate 22 and the substrate. In addition, a reflecting member 29 configured as a porous member is enclosed.

  In the present embodiment, the same reference numerals are given to the same components as those in the above-described embodiment, and the description thereof is omitted.

  The reflecting member 29 configured as a porous member is a member that is in the form of a film, is connected to the side surfaces of both substrates, and has holes of a size such that each particle of the particle group 34 can move. Each particle of the group 34 can move between the substrates. In addition, the reflecting member 29 has a higher degree of porosity on the side in contact with the surface substrate 20 than on the other side, thereby ensuring both shielding by the particle group of the reflecting member 29 and a reduction in the adhesion area to the surface substrate. Therefore, it is preferable.

  When the reflecting member 29 is composed of a porous member, as shown in the display medium 17 shown in FIG. 5, the reflecting member 29 is laminated between the front substrate 20 and the rear substrate 22 and between these substrates. It is preferable to be provided in a direction orthogonal to the direction (that is, the plate surface direction of the surface substrate 20) and to halve the stacking direction between these substrates. Since the configuration of the display medium 17 is the same except that the configurations of the display medium 12 and the reflection member 28 are different, detailed description thereof is omitted.

  The arrangement position of the reflection member 29 may be arranged so as to be laminated on the surface substrate 20, or may be a form in which the reflection member 29 is sealed without a gap between the reflection member 29 substrates.

For the reflecting member 29 configured as a porous member, the material constituting the reflecting member 29 is the same material as the reflecting member 28 configured as an aggregate of the plurality of large-diameter particles 26 described in the first embodiment. be able to. That is, the reflecting member 29 may be configured to include at least one of the fluorescent material and the phosphorescent material described in the first embodiment, a resin, and a color material.
Also, the filling rate of the reflecting member 29 in the cell can be set to the same value as that of the reflecting member 28 described in the first embodiment.

  As the material constituting the porous member, known materials can be used as long as they are not dissolved or deteriorated by the dispersant. For example, as the organic substance, melamine resin, acrylic resin, polyester resin, polyethersulfone can be used. Examples of the inorganic substance include titanium oxide, silica, and magnesium oxide. In the case of a film-like reflecting member using these materials, it can be used as a porous member by providing a hole having a size that allows each particle of the particle group to move.

  The display medium 17 is attached to the mounting unit (not shown) of the display device 10 described in the first embodiment, and the display medium 12 is controlled by the control unit 18 from the electric field forming unit 16. When a voltage is applied to the front electrode 40 and the back electrode 46, an electric field corresponding to the applied voltage is formed in the dispersion medium 50.

  Due to the formed electric field, the particle group 34 moves between the front substrate 20 and the rear substrate 22. For example, when the particles constituting the particle group 34 are charged to the negative electrode, and the positive electrode voltage is applied to the front electrode 40 and the negative electrode voltage is applied to the back electrode 46, the particles constituting the particle group 34 are reflected by the reflecting member 29. And move from the back substrate 22 side to the front substrate 20 side. At this time, when visually recognized from the front substrate 20 side, the color of the particles of the particle group 34 located on the front substrate 20 side is visually recognized as the color of the display medium 17.

  On the other hand, when a negative electrode voltage is applied to the front electrode 40 and a positive electrode voltage is applied to the back electrode 46, the particles constituting the particle group 34 pass through the gaps in the reflecting member 29 and pass from the front substrate 20 side to the back substrate 22 side. Move to. At this time, when viewed from the front substrate 20 side, the color of the reflecting member 29 is viewed as the color of the display medium 17.

  As described above, according to the display medium 17 of the present embodiment, the reflective member 29 configured as a porous member includes at least one of a fluorescent material and a phosphorescent material. Even in a dark environment, the visibility of the display medium 17 in the dark place is reduced due to at least one of the fluorescent material and the phosphorescent material contained in the reflecting member 29 as compared with the case where the present configuration is not used. Can be suppressed.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, each example does not limit the present invention. In addition, unless otherwise indicated, a part shows a weight part.

―Preparation of large particle 1―
As the large particle 26 constituting the reflecting member 28, the large particle 1 was produced.

<Preparation of dispersion A1>
The following components (composition A1) were mixed, and ball milling was performed with 10 mmφ zirconia balls for 20 hours to prepare dispersion A1.

(Composition A1)
• 53 parts by weight of cyclohexyl methacrylate • Titanium oxide 1 (white pigment) (primary particle size 0.3 μm, Type CR63: manufactured by Ishihara Sangyo Co., Ltd.) 45 parts by weight • 5 parts by weight of cyclohexane • GB-U (phosphorescent pigment: ZnS type) (Nemoto Special Chemical Co., Ltd.) 10 parts by weight

<Preparation of Charcoal Cal Dispersion B1>
The following components (composition B1) were mixed and finely pulverized in the same manner as above to prepare a charcoal dispersion liquid B1.

(Composition B1)
・ 40 parts by weight of calcium carbonate ・ 60 parts by weight of water

<Preparation of liquid mixture C1>
The following components (composition C1) were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed liquid C1.

(Composition C1)
・ 2% Serogen 4.3g
-Charcoal cal dispersion B1 8.5g
・ 20% saline 50g

  35 g of the prepared dispersion A1, 1 g of divinylbenzene, and polymerization initiator AIBN: 0.35 g were sufficiently mixed, and deaeration was performed for 10 minutes with an ultrasonic machine. This was added to the mixed liquid C1 and emulsified with an emulsifier. Next, this emulsified liquid was put into a bottle, put into a silicone bottle, used with an injection needle, sufficiently degassed under reduced pressure, and sealed with nitrogen gas.

  Next, this emulsion was reacted at 65 ° C. for 15 hours to prepare particle powder. After cooling the dispersion to room temperature, cyclohexane was removed from the dispersion by freeze drying at −35 ° C. and 0.1 Pa for 2 days. The obtained particle powder was dispersed in ion-exchanged water, calcium carbonate was decomposed with hydrochloric acid water, and filtered. Thereafter, after washing with distilled water was repeated, the particle size was made uniform by passing through a nylon sieve having openings of 20 μm and 25 μm. This was dried to obtain white large-diameter particles 1 having an average particle diameter of 20 μm.

―Preparation of large particle 2―
As the large particle 26 constituting the reflecting member 28, the large particle 2 was produced.

<Preparation of dispersion A2>
The following components (composition A2) were mixed, and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion A2.

(Composition A2)
• 53 parts by weight of cyclohexyl methacrylate • Titanium oxide 1 (white pigment) (volume average primary particle size 0.3 μm, Type CR 63: manufactured by Ishihara Sangyo Co., Ltd.) 45 parts by weight • 5 parts by weight of cyclohexane • N night light (luminova) (phosphorescent pigment (Nemoto Special Chemical Co., Ltd.) 5 parts by weight

<Preparation of charcoal dispersion B2>
The following components (composition B2) were mixed, and finely pulverized with a ball mill in the same manner as above to prepare a charcoal dispersion B.

(Composition B2)
・ 40 parts by weight of calcium carbonate ・ 60 parts by weight of water

<Preparation of mixture C2>
The following components (composition C2) were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed liquid C2.

(Composition C2)
・ 4.3g of 2% serogen aqueous solution
-Charcoal cal dispersion B2 8.5g
・ 20% saline 50g

  Large particle 2 was prepared in the same manner as the above large particle 1 except that dispersion A2 and mixture C2 were used instead of dispersion A1 and mixture C1. The obtained large-diameter particles 2 had a volume average primary particle diameter of 20 μm.

―Preparation of large particle 3―
As the large particle 26 constituting the reflecting member 28, a large particle 3 was produced.

<Preparation of dispersion A3>
The following components (composition A3) were mixed, and ball milling with 10 mmφ zirconia balls was carried out for 20 hours to prepare dispersion A3.

(Composition A3)
• 53 parts by weight of cyclohexyl methacrylate • Titanium oxide 1 (white pigment) (primary particle size 0.3 μm, Tyco CR63: made by Ishihara Sangyo Co., Ltd.) 45 parts by weight • 5 parts by weight of cyclohexane • Lumorgen color (organic fluorescent dye) ( BASF) 10 parts by weight

<Preparation of Charcoal Cal Dispersion B3>
The following components (composition B3) were mixed and finely pulverized in the same manner as above to prepare a charcoal dispersion B3.

(Composition B3)
・ 40 parts by weight of calcium carbonate ・ 60 parts by weight of water

<Preparation of mixture C3>
The following components (composition C3) were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed liquid C3.

(Composition C3)
・ 2% Serogen 4.3g
-Charcoal cal dispersion B3 8.5g
・ 20% saline 50g

  35 g of the prepared dispersion A3, 1 g of divinylbenzene, and polymerization initiator AIBN: 0.35 g were sufficiently mixed, and deaeration was performed for 10 minutes with an ultrasonic machine. This was added to the mixed solution C3 and emulsified with an emulsifier. Next, this emulsified liquid was put into a bottle, put into a silicone bottle, used with an injection needle, sufficiently degassed under reduced pressure, and sealed with nitrogen gas.

  Next, this emulsion was reacted at 65 ° C. for 15 hours to prepare particle powder. After cooling the dispersion to room temperature, cyclohexane was removed from the dispersion by freeze drying at −35 ° C. and 0.1 Pa for 2 days. The obtained particle powder was dispersed in ion-exchanged water, calcium carbonate was decomposed with hydrochloric acid water, and filtered. Thereafter, after washing with distilled water was repeated, the particle size was made uniform by passing through a nylon sieve having openings of 20 μm and 25 μm. This was dried to obtain white large-diameter particles 3 having an average particle diameter of 20 μm.

―Preparation of large particle 4―
As the large particle 26 constituting the reflecting member 28, the large particle 4 was produced.

<Preparation of dispersion A4>
The following components (composition A4) were mixed, and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion A4.

(Composition A4)
• 53 parts by weight of cyclohexyl methacrylate • Titanium oxide 1 (white pigment) (primary particle size 0.3 μm, Type CR63: manufactured by Ishihara Sangyo Co., Ltd.) 45 parts by weight • 5 parts by weight of cyclohexane

  Large particle 4 was prepared in the same manner as the above large particle 1 except that dispersion A4 was used instead of dispersion A1. The obtained large-diameter particles 4 had a volume average primary particle size of 21 μm.

―Magenta particle production―
As the particles constituting the particle group 34, the following magenta particles were produced.

<Preparation of dispersion A5>
The following components (composition A5) were mixed, and ball milling was performed with 10 mmφ zirconia balls for 20 hours to prepare dispersion A5.

(Composition A5)
-53 parts by weight of cyclohexyl methacrylate-3 parts by weight of magenta pigment (Carmine 6B: manufactured by Dainichi Seika Co., Ltd.)-2 parts by weight of charge control agent (COPY CHARGE PSY VP2038: manufactured by Clariant Japan)

<Preparation of Charcoal Cal Dispersion B5>
The following components (composition B5) were mixed, and finely pulverized with a ball mill in the same manner as described above to prepare a charcoal dispersion B5.

(Composition B5)
・ 40 parts by weight of calcium carbonate ・ 60 parts by weight of water

<Preparation of mixture C5>
The following components (composition C5) were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed liquid C5.

(Composition C5)
・ 4.3g of 2% serogen aqueous solution
-Charcoal cal dispersion B5 8.5g
・ 20% saline 50g

  35 g of the above dispersion A5, 1 g of divinylbenzene, and polymerization initiator AIBN: 0.35 g were sufficiently mixed, and deaeration was performed for 10 minutes with an ultrasonic machine. This was added to the mixed solution C5 and emulsified with an emulsifier. Next, this emulsified liquid was put into a bottle, put into a silicone bottle, used with an injection needle, sufficiently degassed under reduced pressure, and sealed with nitrogen gas. Next, it was reacted at 60 ° C. for 10 hours to prepare particles. After cooling, cyclohexane was removed from the dispersion with a freeze dryer at −35 ° C. and 0.1 Pa for 2 days. The obtained particle powder was dispersed in ion-exchanged water, calcium carbonate was decomposed with hydrochloric acid water, and filtered. Thereafter, washing with sufficient distilled water was repeated and dried.

  2 parts by weight of the obtained particles were put into 98 parts by weight of silicone oil together with 2 parts by weight of a nonionic surfactant polyoxyethylene alkyl ether, and stirred and dispersed to prepare a mixture of magenta particles. The obtained magenta particles were negatively charged and the volume average primary particle size was 1 μm.

(Example 1)
-Production of display media and display devices-
On the support substrate made of Corning 1737 glass having a thickness of 0.7 mm as the support substrate 44, ITO was deposited as a back electrode 46 to a thickness of 50 nm by sputtering to produce the back substrate 22. . Thereafter, a layer for the gap member 24 was applied using a photosensitive polyimide varnish, and then exposure and wet etching were performed to form the gap member 24 having a height of 100 μm and a width of 1 mm.
At this time, the distance between the adjacent gap members 24 was 10 mm, and a cell having an area of 2 cm × 2 cm in the plate surface direction area of the back substrate 22 was formed.

  Next, a heat-fusible adhesive layer was formed on the gap member 24.

  Next, the mixed liquid of magenta particles prepared above and the large particle 1 prepared above are mixed at a 1: 1 weight ratio, and filled between the gap members 24 on the back substrate 22 on which the gap members 24 are formed. did.

  Next, on the support substrate made of Corning 1737 glass having a thickness of 0.7 mm as the support substrate 38, ITO is deposited as the surface electrode 40 to a thickness of 50 nm by a sputtering method, whereby the surface substrate 20 Was made. The surface substrate 20 is disposed on the gap member 24 in which the space formed by the gap member 24 and the back substrate 22 is filled with the dispersion medium 50, the large-diameter particles 1 and the magenta particles. The display medium 12 was manufactured by applying heat to 20.

  Next, the display medium 12 is electrically connected to the display device 10 by electrically connecting the front electrode 40 and the back electrode 46 to a product name: MODEL910C manufactured by TREK as the electric field forming unit 16. The configuration was as follows.

<Evaluation>
When the display medium 12 manufactured in Example 1 is irradiated with a fluorescent lamp, the surface electrode 40 of the display medium 12 becomes a positive electrode, and the back electrode 46 becomes a negative electrode, so that the electric field forming unit 16 moves to these electrodes. A voltage of 50 V was applied for 10 seconds.
Since the magenta particles dispersed in the dispersion medium 50 are charged to the negative electrode, the magenta particles are observed to move to the surface electrode 40 on the positive electrode side by applying a voltage to the surface electrode 40 and the back electrode 46. The medium 12 became magenta.

  Next, a voltage of 50 V was applied from the electric field forming unit 16 to these electrodes for 10 seconds so that the front electrode 40 became a negative electrode and the back electrode 46 became a positive electrode. By applying this voltage, the movement of the magenta particles dispersed in the dispersion medium 50 toward the back electrode 46 was observed. Then, the color of the display medium 12 changed from magenta to white.

  In this state, 1000 lux light was irradiated from the surface substrate 20 side of the display medium 12 for 6 hours by an illuminating lamp, and then the display medium 12 was moved to a dark room. As a result, light emission of the large-diameter particles 1 was confirmed.

  Subsequently, in this dark room, a voltage of 50 V is applied to these electrodes from the electric field forming unit 16 for 10 seconds so that the surface electrode 40 of the display medium 12 becomes a positive electrode and the back electrode 46 becomes a negative electrode. After moving to the surface electrode 40, a voltage of 50V was applied for 10 seconds so that the surface electrode 40 became a negative electrode and the back electrode 46 became a positive electrode, and the magenta particles were moved to the back electrode 46 side. When this operation was repeated, the switching of the display could be visually recognized even in the dark room.

(Example 2)
A display medium 12 and a display device 10 were produced in the same manner as in Example 1 except that the large particle 1 was used instead of the large particle 1 used in Example 1.

<Evaluation>
When the display medium 12 manufactured in Example 2 is irradiated with a fluorescent lamp, the surface electrode 40 of the display medium 12 becomes a positive electrode, and the back electrode 46 becomes a negative electrode. A voltage of 50 V was applied for 10 seconds.
Since the magenta particles dispersed in the dispersion medium 50 are charged to the negative electrode, the magenta particles are observed to move to the surface electrode 40 on the positive electrode side by applying a voltage to the surface electrode 40 and the back electrode 46. The medium 12 became magenta.

  Next, a voltage of 50 V was applied from the electric field forming unit 16 to these electrodes for 10 seconds so that the front electrode 40 became a negative electrode and the back electrode 46 became a positive electrode. By applying this voltage, the movement of the magenta particles dispersed in the dispersion medium 50 toward the back electrode 46 was observed. Then, the color of the display medium 12 changed from magenta to white.

  In this state, 1000 lux light was irradiated from the surface substrate 20 side of the display medium 12 for 6 hours by an illuminating lamp, and the display medium 12 was moved to the dark room.

  Subsequently, in this dark room, a voltage of 50 V is applied to these electrodes from the electric field forming unit 16 for 10 seconds so that the surface electrode 40 of the display medium 12 becomes a positive electrode and the back electrode 46 becomes a negative electrode. After moving to the surface electrode 40, a voltage of 50V was applied for 10 seconds so that the surface electrode 40 became a negative electrode and the back electrode 46 became a positive electrode, and the magenta particles were moved to the back electrode 46 side. When this operation was repeated, the switching of the display could be visually recognized even in the dark room.

(Example 3)
First, as a reflecting member, a reflecting member 29 (see FIG. 5) was produced by the following method.

  50 parts by weight of n-methyl, 2-pyrrolidone, 40 parts by weight of PES resin (Sumitomo Chemical Co., Sumika Excel PES4800S), 10 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd., Tyco CR63), GB-U (phosphorescent) Pigment: ZnS type) (manufactured by Nemoto Special Chemical Co., Ltd.) 2.5 parts by weight were mixed and stirred for 5 minutes with a Heidolph homogenizer Silent Crusher M.

  The obtained solution was applied to a glass substrate with a thickness of 300 μm and dried at 150 ° C. for 2 hours to obtain a white PES film having a thickness of 100 μm. In the obtained PES film, using an excimer laser, pores having a pore diameter of 10 μm and a hole pitch of 50 μm were formed, and a reflective member 29 was obtained.

Next, on the support substrate made of Corning 1737 glass having a thickness of 0.7 mm as the support substrate 44, ITO is deposited as a back electrode 46 to a thickness of 50 nm by a sputtering method. Was made. Thereafter, a layer for the gap member 24 was applied using a photosensitive polyimide varnish, and then exposure and wet etching were performed to form the gap member 24 having a height of 100 μm and a width of 1 mm.
At this time, the distance between the adjacent gap members 24 was 10 mm.
Next, a heat-fusible adhesive layer was formed on the gap member 24 formed on the back substrate 22.

Further, on the support substrate made of Corning 1737 glass having a thickness of 0.7 mm as the support substrate 38, ITO is deposited as the surface electrode 40 to a thickness of 50 nm by a sputtering method. Produced. After applying a layer for the gap member 24 to the surface substrate 20 using a photosensitive polyimide varnish, the gap member 24 having a height of 100 μm and a width of 1 mm was formed by performing exposure and wet etching. At this time, the distance between the adjacent gap members 24 was 10 mm.
Next, a heat-fusible adhesive layer was formed on the gap member 24 formed on the surface substrate 20.

  The adhesive layer on the gap member 24 formed on the back substrate 22 and the adhesive layer on the gap member 24 formed on the front substrate 20 were bonded together so as to sandwich the reflection member 29 produced above. Then, the display medium 17 (refer FIG. 5) was produced by filling the liquid mixture of the produced said magenta particle between the back substrate 22 and the surface substrate 20 from the filling port provided previously.

  Next, the display medium 17 is electrically connected to the display device 10 by electrically connecting the surface electrode 40 and the back electrode 46 to a product name: MODEL910C manufactured by TREK as the electric field forming unit 16. The configuration was as follows.

<Evaluation>
When the display medium 17 manufactured in Example 3 is irradiated with a fluorescent lamp, the surface electrode 40 of the display medium 17 becomes a positive electrode, and the back electrode 46 becomes a negative electrode. A voltage of 50 V was applied for 10 seconds.
Since the magenta particles dispersed in the dispersion medium 50 are charged to the negative electrode, the magenta particles are observed to move to the surface electrode 40 on the positive electrode side by applying a voltage to the surface electrode 40 and the back electrode 46. Medium 17 was magenta.

  Next, a voltage of 50 V was applied from the electric field forming unit 16 to these electrodes for 10 seconds so that the front electrode 40 became a negative electrode and the back electrode 46 became a positive electrode. By applying this voltage, the movement of the magenta particles dispersed in the dispersion medium 50 toward the back electrode 46 was observed. Then, the color of the display medium 17 changed from magenta to white.

  In this state, after 1000 lux light was irradiated from the surface substrate 20 side of the display medium 17 by the illumination lamp for 6 hours, the display medium 17 was moved to the dark room, and light emission of the reflecting member 29 was confirmed.

  Subsequently, in this dark room, a voltage of 50 V is applied to these electrodes from the electric field forming unit 16 for 10 seconds so that the surface electrode 40 of the display medium 17 becomes a positive electrode and the back electrode 46 becomes a negative electrode. After moving to the surface electrode 40, a voltage of 50V was further applied for 10 seconds so that the surface electrode 40 became a negative electrode and the back electrode 46 became a positive electrode, and magenta particles were moved to the back electrode 46 side. When this operation was repeated, the switching of the display could be visually recognized even in the dark room.

Example 4
A display medium 12 and a display device 10 were produced in the same manner as in Example 1 except that the large particle 3 was used instead of the large particle 1 used in Example 1.

<Evaluation>
The display medium 12 manufactured in Example 4 was subjected to 50 V from the electric field forming unit 16 to these electrodes so that the surface electrode 40 of the display medium 12 became a positive electrode and the back electrode 46 became a negative electrode when irradiated with a fluorescent lamp. Was applied for 10 seconds.
Since the magenta particles dispersed in the dispersion medium 50 are charged to the negative electrode, the magenta particles are observed to move to the surface electrode 40 on the positive electrode side by applying a voltage to the surface electrode 40 and the back electrode 46. The medium 12 became magenta.

  Next, a voltage of 50 V was applied from the electric field forming unit 16 to these electrodes for 10 seconds so that the front electrode 40 became a negative electrode and the back electrode 46 became a positive electrode. By applying this voltage, the movement of the magenta particles dispersed in the dispersion medium 50 toward the back electrode 46 was observed. Then, the color of the display medium 12 changed from magenta to white.

  In this state, 1000 lux light was irradiated from the surface substrate 20 side of the display medium 12 for 6 hours by an illuminating lamp, and the display medium 12 was moved to the dark room.

  Subsequently, in this dark room, a voltage of 50 V is applied to these electrodes from the electric field forming unit 16 for 10 seconds so that the surface electrode 40 of the display medium 12 becomes a positive electrode and the back electrode 46 becomes a negative electrode. After moving to the surface electrode 40, a voltage of 50V was further applied for 10 seconds so that the surface electrode 40 became a negative electrode and the back electrode 46 became a positive electrode, and magenta particles were moved to the back electrode 46 side. When this operation was repeated, the switching of the display could be visually recognized even in the dark room.

(Comparative Example 1)
A display medium 12 and a display device 10 were produced in the same manner as in Example 1 except that large particles 4 were used instead of the large particles 1 used in Example 1.

<Evaluation>
The display medium 12 manufactured in Comparative Example 1 is subjected to 50 V from the electric field forming unit 16 to these electrodes so that the surface electrode 40 of the display medium 12 becomes a positive electrode and the back electrode 46 becomes a negative electrode when irradiated with a fluorescent lamp. Was applied for 10 seconds.
Since the magenta particles dispersed in the dispersion medium 50 are charged to the negative electrode, the magenta particles are observed to move to the surface electrode 40 on the positive electrode side by applying a voltage to the surface electrode 40 and the back electrode 46. The medium 12 became magenta.

  Next, a voltage of 50 V was applied from the electric field forming unit 16 to these electrodes for 10 seconds so that the front electrode 40 became a negative electrode and the back electrode 46 became a positive electrode. By applying this voltage, the movement of the magenta particles dispersed in the dispersion medium 50 toward the back electrode 46 was observed. Then, the color of the display medium 12 changed from magenta to white.

  In this state, after 1000 lux light was irradiated from the surface substrate 20 side of the display medium 12 by the illumination lamp for 6 hours, when the display medium 12 was moved to the dark room, the display medium could not be visually recognized.

  Subsequently, in this dark room, a voltage of 50 V is applied to these electrodes from the electric field forming unit 16 for 10 seconds so that the surface electrode 40 of the display medium 12 becomes a positive electrode and the back electrode 46 becomes a negative electrode. After moving to the surface electrode 40, a voltage of 50V was further applied for 10 seconds so that the surface electrode 40 became a negative electrode and the back electrode 46 became a positive electrode, and magenta particles were moved to the back electrode 46 side. This operation was repeated, but the display change could not be visually confirmed.

  Thus, it can be seen that the display switching visibility when the magenta particles in the dark room are moved to the front substrate 20 side and the rear substrate 22 side is better than that of the first comparative example. For this reason, it can be said that the display media in Examples 1 to 4 were able to suppress a decrease in visibility in a dark place as compared with the display media in Comparative Example 1.

1 is a schematic configuration diagram of a display device and a display medium according to a first embodiment. It is a schematic diagram which shows an example of a structure of a large diameter particle. It is a schematic diagram which shows the form different from FIG. 1 of the display medium which concerns on 1st Embodiment. It is a schematic diagram which shows the form different from FIG. 1 of the display medium which concerns on 1st Embodiment. It is a schematic block diagram of the display medium which concerns on 2nd Embodiment. 1 is a schematic configuration diagram of a display medium and a display device according to a first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Display apparatus 12 Display medium 12, 17 Display medium 16 Electric field formation part 20 Surface substrate 22 Back substrate 26 Large diameter particle | grains 28 and 29 Reflective member 34 Particle group 34 Particle group 50 Dispersion medium

Claims (14)

A pair of substrates at least one having translucency and disposed with a gap;
A group of particles enclosed between the pair of substrates and moving between the substrates in response to an electric field formed between the substrates;
A dispersion medium enclosed between the pair of substrates and for dispersing the particle group;
A reflecting member that is disposed between the pair of substrates and has a gap through which the particle group passes and has an optical reflection characteristic different from that of the particle group, the reflecting member containing at least one of a phosphorescent material and a fluorescent material When,
A display medium comprising:   The display medium according to claim 1, wherein the color of the reflecting member is white.   The display medium according to claim 1, wherein the reflection member is configured by an aggregate of particles.   The display medium according to claim 1, wherein the reflection member is configured by an aggregate of particles having a volume average primary particle size larger than particles of the particle group.   The display medium according to claim 1, wherein the reflection member is formed of a porous member having a through hole through which the particle group passes.   The display medium according to claim 1, wherein the reflection member is disposed with a gap between the pair of substrates.   The display medium according to claim 1, wherein the reflecting member is unevenly distributed on one of the pair of substrates. A pair of substrates at least one having translucency and disposed with a gap;
A group of particles enclosed between the pair of substrates and moving between the substrates in response to an electric field formed between the substrates;
A dispersion medium enclosed between the pair of substrates and for dispersing the particle group;
A reflecting member that is disposed between the pair of substrates and has a gap through which the particle group passes and has an optical reflection characteristic different from that of the particle group, the reflecting member containing at least one of a phosphorescent material and a fluorescent material And a display medium comprising
A display device comprising electric field forming means for forming an electric field between the pair of substrates.   The display device according to claim 8, wherein the color of the reflecting member is white.   The display device according to claim 8, wherein the reflection member is configured by an aggregate of particles.   The display device according to claim 8, wherein the reflection member is configured by an aggregate of particles having a volume average primary particle size larger than that of the particles of the particle group.   The display device according to claim 8, wherein the reflection member is formed of a porous member having a through hole through which the particle group moves.   The display device according to claim 8, wherein the reflecting member is disposed with a gap between the pair of substrates.   The display device according to claim 8, wherein the reflecting member is unevenly distributed on one of the pair of substrates.

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