JP2009003179A - Display medium, display device and display program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display medium, capable of suppressing degradation of image storage property, a display device and a display program. <P>SOLUTION: The display medium comprises a pair of substrates at least one of which is translucent, the substrates being disposed with a space; a particle group which is sealed between the pair of substrates and moves according to an electric field formed between the substrates; a dispersion medium for dispersing the particle group, which is sealed between the pair of substrates; and a reflecting member provided between the pair of substrates. The reflecting member has pores for passing the particle group and an optical reflecting characteristic different from that of the particle group, and is changed to an arrest state for arresting passing of the particle group through the pores or a release state for releasing the arrested state by applying a stimulus thereto. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  Conventionally, a display technique using particle electrophoresis has been proposed as a sheet-like display medium that can be rewritten repeatedly. In this technique, an electrophoretic particle is electrophoresed to attach an electrophoretic particle having a desired color to the observation surface side of the display medium, thereby displaying an image of a target color.

  Various improvements have been made to the technology using electrophoretic particles. For example, a porous layer having a color different from that of the electrophoretic particles is provided between the substrates, and the particles are passed through the pores in the porous layer. A technique for displaying both the color of the porous layer and the color of the particles to be electrophoresed by electrophoresis of the group is known (for example, see Patent Documents 1 to 3).

Sho 50-015120 JP 2003-186062 A JP 2001-242492 A

  It is an object of the present invention to provide a display medium, a display device, and a display program that can suppress a decrease in image storability.

  In order to achieve the above object, an invention according to claim 1 is formed between a pair of substrates, at least one of which is translucent and disposed with a gap, and between the pair of substrates. A particle group that moves according to the electric field, a dispersion medium that is enclosed between the pair of substrates and disperses the particle group, and a hole that is provided between the pair of substrates and through which the particle group passes. In addition, the reflecting member has an optical reflection characteristic different from that of the particle group and changes to a blocking state in which the particle group is prevented from passing through the hole or a released state in which the blocking state is released by applying a stimulus. And a display medium.

  The invention according to claim 2 is characterized in that the reflecting member is provided between the pair of substrates, has a hole through which the particle group passes and has an optical reflection characteristic different from that of the particle group, and A first member that is provided in the porous member and changes to a blocking state in which the particle group is prevented from passing through the pores of the porous member by being given a stimulus or a released state in which the blocking state is released; The display medium according to claim 1, further comprising:

  The invention according to claim 3 is characterized in that the first member is provided in at least the hole of the porous member and swells or contracts by the application of the stimulus. It is.

  According to a fourth aspect of the present invention, in the display medium according to the third aspect, the first member is a polymer gel that changes in volume by absorbing or releasing the dispersion medium upon application of the stimulus. It is.

  The invention according to claim 5 is characterized in that the particle group is charged in advance, the first member is provided on a surface of the porous member, and charging characteristics are changed by applying the stimulus. 2. The display medium according to 2.

  The invention according to claim 6 is characterized in that the particle group is charged in advance, the first member is provided on a surface of the porous member, and changes to hydrophobic or hydrophilic by the application of the stimulus. The display medium according to claim 2.

  The invention according to claim 7 is the display medium according to any one of claims 1 to 6, wherein the stimulus is electricity.

  The invention according to claim 8 is the display medium according to any one of claims 1 to 6, wherein the stimulus is heat or light.

  According to the ninth 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 particles that are enclosed between the pair of substrates and move according to an electric field formed between the substrates. A group, a dispersion medium enclosed between the pair of substrates, and a dispersion medium for dispersing the particle group, and a hole provided between the pair of substrates, having a hole through which the particle group passes, and different from the particle group A reflective medium that has a reflective property and changes to a blocked state that prevents passage of the particles to the hole or a released state that releases the blocked state when a stimulus is applied; A display device comprising: stimulus applying means for applying a stimulus to the reflecting member of the display medium; and voltage applying means for forming an electric field between the pair of substrates by applying a voltage to the display medium. It is.

  According to a tenth 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 particles that are enclosed between the pair of substrates and move according to an electric field formed between the substrates. A group, a dispersion medium enclosed between the pair of substrates, and a dispersion medium for dispersing the particle group, and a hole provided between the pair of substrates, having a hole through which the particle group passes, and different from the particle group A reflective medium that has a reflective property and changes to a blocked state that prevents passage of the particles to the hole or a released state that releases the blocked state when a stimulus is applied; A display device comprising: stimulus applying means for applying a stimulus to the reflecting member of the display medium; and voltage applying means for forming an electric field between the pair of substrates by applying a voltage to the display medium. Display An image display program for causing a computer to execute a process for controlling the stimulus applying means to apply a stimulus for bringing the reflecting member into the released state, and between a pair of substrates of the display medium A second step of controlling the voltage applying means so as to form an electric field, and a third step of controlling the stimulus applying means to apply a stimulus for bringing the reflecting member into the blocking state. This is a display program to be executed.

  According to the first aspect of the invention, there is an effect that it is possible to suppress deterioration in image quality retention.

  According to the invention which concerns on Claim 2, there exists an effect that the fall of image quality retainability can be suppressed easily with a simple structure.

  According to the invention which concerns on Claim 3, there exists an effect that the change speed to a blocking state or a cancellation | release state can be improved.

  According to the invention which concerns on Claim 4, while changing to the blocking state or the cancellation | release state can be improved, a density | concentration change can also be suppressed.

  According to the fifth aspect of the invention, the image quality retention can be further improved.

  According to the sixth aspect of the present invention, it is possible to easily suppress deterioration in image quality retention with a simple configuration.

  According to the invention concerning Claim 7, compared with the case where stimuli other than electrical stimulation are used, there exists an effect that the structure of a display medium can be simplified.

  According to the invention which concerns on Claim 8, it can change to a blocking state or a cancellation | release state easily compared with the case where irritation | stimulation other than a heat | fever and optical stimulation is used.

  According to the invention concerning Claim 9, there exists an effect that the display apparatus which can suppress the fall of the image quality maintenance property of a display medium can be provided.

  According to the invention which concerns on Claim 10, there exists an effect that the display program which can suppress the fall of the image quality maintenance property of a display medium can be provided.

  Hereinafter, the present invention will be described in detail.

(First embodiment)
As shown in FIG. 1, a display medium 12 according to an embodiment of the present invention includes a display substrate 18 that is an image display surface, a back substrate 20 that faces the display substrate 18 with a gap, and a distance between these substrates. The gap member 34 that holds the display substrate 18 and the back substrate 20 into a plurality of cells, includes a particle group 36 enclosed in each cell, a dispersion medium 42, and a reflection member 38. Yes.

  The cell indicates a region surrounded by the display substrate 18, the back substrate 20, and the gap member 34. The dispersion medium 42 is sealed in the cell. Particle groups 36 (details will be described later) are dispersed in the dispersion medium 42 and move in the dispersion medium 42 between the display substrate 18 and the back substrate 20 according to the electric field strength formed in the cell. Further, a porous member 48 whose details will be described later is provided in the cell.

  It should be noted that the gap member 34 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 colors for each pixel. It can be configured to be possible. Note that FIGS. 1 and 6 are shown by focusing on one cell for the sake of explanation and simplification. The same applies to FIGS. 7, 9, 10, 11, 13, 14, and 16 in the second embodiment, the third embodiment, and the fourth embodiment described later. For the sake of simplification of the description and the drawings, one cell has been noted.

  The display substrate 18 has a configuration in which a surface electrode 24 and a surface layer 26 are sequentially stacked on a support substrate 22. The back substrate 20 has a structure in which a back electrode 30 and a surface layer 32 are sequentially laminated on a support substrate 28.

  Examples of the support substrate 22 and the support substrate 28 include glass and plastics such as polycarbonate resin, acrylic resin, polyimide resin, polyester resin, epoxy resin, and polyether sulfone resin.

  The back electrode 30 and the surface electrode 24 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 normally 100 to 2000 mm according to the vapor deposition method and the sputtering method. The back electrode 30 and the surface electrode 24 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 device or a printed circuit board. it can.

  Further, the surface electrode 24 may be embedded in the support substrate 22. Similarly, the back electrode 30 may be embedded in the support substrate 28. In this case, since the material of the support substrate 22 and the support substrate 28 may affect the charging characteristics and fluidity of each particle of the particle group 36, the material is selected according to the composition of each particle of the particle group 36.

  Note that the back electrode 30 and the surface electrode 24 may be separated from the display substrate 18 and the back substrate 20 and disposed outside the display medium 12. In this case, the display medium 12 is sandwiched between the back electrode 30 and the surface electrode 24, the distance between the back electrode 30 and the surface electrode 24 is increased, and the electric field strength is reduced. Thus, it is necessary to devise measures such as reducing the thickness of the support substrate 22 and the support substrate 28 of the display medium 12 and reducing the distance between the support substrate 22 and the support substrate 28 so that the electric field strength of the display medium 12 can be obtained.

  In the above description, the case where both the display substrate 18 and the back substrate 20 are provided with the electrodes (the front electrode 24 and the back electrode 30) has been described.

  In order to enable active matrix driving, the support substrate 22 and the support substrate 28 may include a TFT (thin film transistor) for each pixel. The TFTs are preferably formed not on the display substrate but on the back substrate 20 because wiring can be easily laminated and components can be easily mounted.

  In addition, when the display medium 12 is a simple matrix drive, the configuration of a display device 10 including the display medium 12 described later can be simplified, and the active matrix drive using TFTs is simpler than the simple matrix drive. Display speed can be increased.

  When the surface electrode 24 and the back electrode 30 are formed on the support substrate 22 and the support substrate 28, respectively, the electrodes between the electrodes that cause breakage of the surface electrode 24 and the back electrode 30 and adhesion of each particle of the particle group 36 are obtained. In order to prevent the occurrence of leaks, it is preferable to form the surface layer 26 and the surface layer 32 as dielectric films on the surface electrode 24 and the back electrode 30 as necessary.

  As materials for forming the surface layer 26 and the surface layer 32, polycarbonate, polyester, polystyrene, polyimide, epoxy, polyisocyanate, polyamide, polyvinyl alcohol, polybutadiene, polymethyl methacrylate, copolymerized nylon, ultraviolet curable acrylic resin, fluororesin Etc. can be used.

In addition to the insulating material described above, an insulating material containing a charge transporting substance in an insulating material (volume low efficiency of 10 ⁹ Ω · cm or more) can be used. By containing a charge transport material, particle chargeability is improved by injecting charges into the particles, and when the charge amount of the particles becomes extremely large, the charge of the particles is leaked and the charge amount of the particles is stabilized.

Examples of the charge transport material include a hydrazone compound, a stilbene compound, a pyrazoline compound, and a triarylamine 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. Since the dielectric film may affect the charging characteristics and fluidity of the particles, it is selected according to the composition of the particles. Since the display substrate which is one of the substrates needs to transmit light, it is preferable to use a transparent one of the above materials.

―Gap member―
The gap member 34 for holding the gap between the display substrate 18 and the back substrate 20 is formed so as not to impair the transparency of the display substrate 18, and is a thermoplastic resin, thermosetting resin, electron beam curable resin, photocuring. It can be formed of resin, rubber, metal and the like.

  The gap member 34 includes a cell type and a particle type. An example of the cellular type is a net. Since the net is easy to obtain and inexpensive, and the thickness is relatively uniform, it is useful when manufacturing an inexpensive display medium 12. The net is not suitable for displaying a fine image, and is preferably used for a large-sized image display device that does not require a high resolution. In addition, as other cellular spacers, a sheet in which holes are formed in a matrix by etching, laser processing, or the like can be cited. In this sheet, the thickness, the shape of the holes, the size of the holes, etc. are compared with the net. Easy to adjust. For this reason, the sheet is used as an image display medium for displaying a fine image, and the contrast is further improved.

The gap member 34 may be integrated with one of the display substrate 18 and the back substrate 20, and the support substrate 22 or the support substrate 28 is etched, laser processed, or a prefabricated mold is used and pressed. The support substrate 22 or the support substrate 28 having a cell pattern of any size and the gap member 34 can be produced by processing, printing, or the like.
In this case, the gap member 34 can be produced on either the display substrate 18 side, the back substrate 20 side, or both.

  The gap member 34 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 34 is preferably transparent, and glass particles can be used in addition to transparent resin particles such as polystyrene, polyester, and acrylic.

-Particle group-
In the dispersion medium 42 of the display medium 12 of the present invention, an electric field having a specific strength is formed between the display substrate 18 and the back substrate 20, whereby the dispersion medium is interposed between the display substrate 18 and the back substrate 20. In the dispersion medium 42, the particle group 36 having a voltage range necessary for moving in accordance with the electric field is dispersed in the dispersion medium 42.

  For example, as shown in FIG. 2, when the potential difference per unit distance is increased from 0 V between the display substrate 18 and the rear substrate 20 and a potential difference exceeding + mV is generated between the substrates, the particle group 36 moves between the substrates. Then, for example, the substrate moves from the display substrate 18 side to the back substrate 20 side. Similarly, when the potential difference between the display substrate 18 and the back substrate 20 is increased from 0 V to the minus side and a potential difference exceeding −mV occurs between the substrates, the particle group 36 moves between the substrates, for example, The particle group 36 located on the back substrate 20 side moves to the display substrate 18 side.

  Thus, the particle group 36 moves between substrates when a voltage within a voltage range that causes a potential difference within a predetermined range between the substrates is applied.

  In the present embodiment, in order to simplify the description, the absolute value of the voltage moving from the state positioned on one side of the display substrate 18 and the rear substrate 20 to the other side and the position positioned on the other side The absolute value of the voltage that moves from the selected state to the one-sided state will be described as being the same (+ mV and −mV as shown in FIG. 2). It differs depending on the configuration of 12 and the type of particle group 36, and is not limited to the same value.

  In the present embodiment, in order to simplify the description, a case where one type of particle group 36 having a voltage range necessary for moving in accordance with an electric field is dispersed in the dispersion medium 42. As will be described, a plurality of types of particle groups 36 having different voltage ranges may be dispersed in the dispersion medium 42. Further, different colors may be used for each type. In this way, it is possible to display a color image on the display medium 12.

  Here, the range of voltage necessary for the particle group 36 to move in accordance with the electric field is the electrostatic force of the particle group 36, the magnetic force of the particle group 36, and the weak interparticle force between the particles constituting the particle group 36. Determined by the flow resistance of the particles, the van der Waals force between the particles and between the particles and the display substrate 18 and the back substrate 20. Therefore, any one of the average charge amount of the particles constituting the particle group 36, the flow resistance to the dispersion medium 42 on the particle surface, the average magnetic amount (magnetization strength), the particle size of the particles, and the shape factor of the particles. Alternatively, by adjusting a plurality, it is possible to adjust the voltage range necessary for moving according to the electric field of the particle group 36.

  The particles constituting the particle group 36 include glass beads, insulating metal oxide particles such as alumina and titanium oxide, 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 colloidal particles having a plasmon coloring function.

  Examples of the thermoplastic resin used for producing each particle constituting the particle group 36 include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl acetate, vinyl propionate, and benzoic acid. Vinyl esters such as vinyl and vinyl butyrate, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, etc. α-methylene aliphatic monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone alone It can be exemplified coalescence or copolymer.

  Examples of the thermosetting resin used in the production of each particle constituting the particle group 36 include a crosslinked copolymer mainly composed of divinylbenzene and a crosslinked resin such as crosslinked polymethyl methacrylate, a phenol resin, a urea resin, and a melamine resin. , Polyester resin, silicone resin and the like. 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.
Also, porous sponge-like particles or hollow particles enclosing air can be used as white particles.

  If necessary, a charge control agent may be mixed in the resin of each particle constituting the particle group 36. 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 and the surface of each particle constituting the particle group 36 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 silicon oxide (silica), titanium oxide, and metal oxides such as 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. Similarly, 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, fluorine Examples include negatively chargeable ones such as modified silicone oils. These are selected according to the desired resistance of the external additive.

Of these external additives, well-known hydrophobic silica and hydrophobic titanium oxide are preferable, and 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 primary particles of the external additive are generally 5 nm to 100 nm, preferably 10 nm to 50 nm, but are 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. Generally, the amount of the external additive is 0.01 part by weight or more and 3 parts by weight or less, more preferably 0.05 part by weight or more and 1 part by weight or less with respect to 100 parts by weight of the particles.

  The external additive may be added only 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, the external additive may be applied to the particle surface with impact force, or the particle surface may be heated to firmly fix the external additive to the particle surface. desirable. 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.

Any conventionally known method may be used as a method for producing each particle constituting the particle group 36. 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 may be prepared. Furthermore, the resin, the colorant, the charge control agent, and the dispersion can be plasticized, the dispersion medium does not boil, and the temperature is lower than the decomposition point of the resin, the charge control agent and / or the colorant. There is a method using an appropriate apparatus capable of dispersing and kneading the raw material of the medium. 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 a temperature of from 0 ° C. to 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, a raw material that has been sufficiently fluidized is 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.

  As each particle constituting the particle group 36 used in the display medium 12 of the present embodiment, a metal colloid particle having a plasmon coloring function may be used as a particle exhibiting a different coloring property for each type in a dispersed state. Good.

  Examples of the metal of the metal colloidal particles include noble metals and copper (hereinafter collectively referred to as “metals”), and the noble metals are not particularly limited. For example, gold, silver, copper, ruthenium, rhodium, palladium , Osmium, iridium, platinum and the like. Among the metals, gold, silver, copper, and platinum are preferable.

  The metal colloidal particles can be prepared by a chemical method in which metal ions are reduced to form nanoparticles through metal atoms and metal clusters, or metal that has been converted into particles by evaporating bulk metal in an inert gas. A physical method is known in which a metal thin film is formed by trapping or vacuum vapor deposition on a polymer thin film and then heated to break the metal thin film and disperse the metal particles in the polymer in a solid state. The chemical method does not require the use of a special apparatus and is advantageous for the preparation of the metal colloidal particles of the present invention. Therefore, general examples will be described later, but the present invention is not limited thereto.

  The metal colloidal particles are formed from the metal compound. The metal compound is not particularly limited as long as it contains the metal, and examples thereof include chloroauric acid, silver nitrate, silver acetate, silver perchlorate, chloroplatinic acid, potassium chloroplatinate, and copper (II) chloride. , Copper acetate (II), copper sulfate (II) and the like.

  The metal colloid particles can be obtained as a dispersion of metal colloid particles protected by a dispersant by dissolving the metal compound in a solvent and then reduced to a metal. It can also be obtained in the form of a solid sol. Any form other than these may be used.

  When the metal compound is dissolved, a polymer pigment dispersant described later can be used. By using a polymer pigment dispersant, it can be obtained as stable metal colloidal particles protected with the dispersant. At this time, it is possible to control the concentration of the dispersant adsorbed on the surface of the metal colloidal particles by performing the type, concentration and stirring time of the polymer pigment dispersant under desired conditions. That is, by increasing the concentration of the polymer pigment dispersant or increasing the stirring time, the amount of the polymer pigment dispersant adsorbed on the surface of the metal colloid particles can be increased. Thereby, the mobility of the metal colloid particles can be controlled.

  When the metal colloid particles in the present embodiment are used, they can be used as a dispersion of the metal colloid particles obtained above, or the solid sol from which the solvent has been removed can be redispersed in a solvent. The present invention is not particularly limited.

  When used as a dispersion of the metal colloidal particles, the solvent used for the preparation is preferably an insulating liquid described later. When the solid sol is redispersed and used, any solvent can be used as the solvent for preparing the solid sol, and is not particularly limited. The solvent for redispersion is preferably an insulating liquid described later.

  The metal colloidal particles can be colored in various colors depending on the type and shape of the metal and the volume average primary particle size. Therefore, by using particles whose metal type, shape, and volume average primary particle diameter are controlled, various hues including RGB coloring can be obtained, and the display medium 12 of the present invention can be used as a color display medium. it can. Furthermore, an RGB full-color display medium can be obtained by controlling the shape and particle size of the metal and the resulting metal colloid particles.

  The volume average primary particle diameter of the metal colloid particles for exhibiting RGB colors of R, G, and B depends on the metal used, the particle preparation conditions, shape, particle size, etc. However, for example, in the case of colloidal gold particles, as the volume average primary particle diameter increases, R color development, G color development, and B color development tend to be exhibited.

  As a method for measuring the volume average primary particle diameter in the present invention, a laser diffraction scattering method is employed in which a particle group is irradiated with laser light, and the average particle diameter is measured from the intensity distribution pattern of diffraction and scattered light emitted therefrom. .

  The content (% by weight) of the particle group 36 with respect to the total mass in the cell is not particularly limited as long as the desired hue is obtained, and the content can be adjusted depending on the thickness of the cell. It is effective as the display medium 12. That is, in order to obtain a desired hue, when the cell is thick, the content is small, and when the cell is thin, the content can be increased. Generally, it is 0.01 to 50% by weight.

  The colloidal metal particles can be prepared by, for example, a general preparation method described in the document “Synthesis / preparation of metal nanoparticles, control technology and application development” (published by Technical Information Association, 2004). Can be prepared. One example will be described below, but the present invention is not limited to this.

-Reflective member-
In the display medium 12 of the present invention, a reflecting member 38 is enclosed in each cell. The reflecting member 38 has an optical reflection characteristic different from that of the particle group 36, and has a hole through which at least each particle constituting the particle group 36 passes.

  In this embodiment, the reflecting member 38 has an optical reflection characteristic different from that of the particle group 36 and a porous member 48 having at least pores through which each particle constituting the particle group 36 passes. A first member 46 that is provided on the member 48 and changes to a blocking state in which the particle group 36 is prevented from passing through the pores of the porous member 48 by applying a stimulus or a released state in which the blocking is released. Has been

  As described above, the porous member 48 has an optical reflection characteristic different from that of the particle group 36, and has a hole through which at least each particle constituting the particle group 36 passes.

  This hole is a hole having a size through which each particle constituting the particle group 36 can pass, and is at least a hole communicating with the direction of the electric field gradient formed in the display medium 12. In the present embodiment, an electric field gradient formed between the display substrate 18 and the back substrate 20 by the surface electrode 24 and the back electrode 30, that is, a hole that communicates at least in the direction in which the display substrate 18 and the back substrate 20 face each other. It is.

  Here, “having an optical reflection characteristic different from that of the particle group 36” means a hue when the dispersion medium 42 in which only the particle group 36 is dispersed and the porous member 48 are visually observed. This means that there is a difference that can distinguish between the two in terms of brightness, brightness, freshness, and the like.

  The porous member 48 preferably has a function of shielding the particle group 36. Here, “concealment” in the present embodiment means a case where the transmittance is 50% or less with respect to visible light.

  Therefore, when the particle group 36 is closer to the display substrate 18 than the porous member 48, the color of the particle group 36 is different. When the particle group 36 is closer to the rear substrate 20 than the porous member 48, 48 colors are displayed on the display medium 12.

The color of the porous member 48 is preferably white because the display can be performed with a bright white background, the whiteness is preferably 30% or more, and 40% or more. Particularly preferred.
The whiteness is a measure of whiteness, and is specifically a value measured using a Hunter whiteness meter or X-rite colorimeter according to the method described in JIS-P8123.

  The thickness of the porous member 48 is desirably at least equal to or greater than the volume average primary particle size of the particles constituting the particle group 36. Since the particle group 36 existing on the back substrate 20 side of the porous member 48 may be observed from the hole portion of the porous member 48, the thickness of the porous member 48 is the volume average primary particle size of the particle group 36. It is further desirable that it is three times or more.

Specifically, the thickness of the porous member 48 depends on the distance between the display substrate 18 and the back substrate 20, but is preferably 0.1 μm or more and 5000 μm or less, preferably 1 μm or more and 500 μm or less. More preferably it is.
If the thickness of the porous member 48 is less than 0.1 μm, there may be a problem that sufficient color developability cannot be obtained. If the thickness exceeds 5000 μm, the distance between the electrodes becomes large and a high driving voltage is required. There is a problem to say.

  The refractive index of the entire region of the porous member 48 is preferably in the range of the refractive index of the dispersion medium −0.2 or more and the refractive index of the dispersion medium 42 +0.2 or less. The refractive index of the dispersion medium 42 − The refractive index is more preferably in the range of 0.05 or more and the refractive index of the dispersion medium 42 +0.05 or less, and most preferably the same as the refractive index of the dispersion medium 42.

  If the refractive index of the porous member 48 is within the above range, light scattering caused by the porous member 48 can be further suppressed as compared with the case where the refractive index is outside the above range, so that the saturation is further high and clear. It is considered that color display can be performed.

  The refractive index can be measured by using a laser measuring instrument, and for particles by the Becke line method, the immersion method, the method of measuring attenuation for each wavelength, the method of measuring the critical angle of refraction, and the like.

  In addition, it is particularly preferable that the arrangement position of the porous member 48 in each cell is arranged so as to exist in the entire plate surface direction of the display substrate 18. That is, the porous member 48 may be disposed along a direction that is orthogonal to the electric field gradient direction formed between the display substrate 18 and the back substrate 20 as much as possible (a direction along the plate surface of the display substrate 18). preferable.

  The form of the porous member 48 is not particularly limited as long as it has a hole through which the particle group 36 passes and has an optical reflection characteristic different from that of the particle group 36 as described above. Titanium oxide Aggregates of particulate members such as inorganic material particles composed of materials such as zinc oxide, and organic material particles composed of materials such as methyl methacrylate resin, styrene acrylic resin, silicone resin, polytetrafluoroethylene resin A body, a resin sheet, a nonwoven fabric, etc. may be utilized.

  When the porous member 48 is configured as an aggregate of particles, the volume average primary particle size of the particles is not particularly limited, but the porous member 48 formed of the aggregate of particles is referred to as the display substrate 18. It is desirable to have a volume average primary particle size that allows the particle group 36 to pass through such that the gap between adjacent particles becomes the above-mentioned hole when arranged in a region between the back substrate 20.

  Therefore, when the porous member 48 is configured as an aggregate of particles, the volume average primary particle size of the particles to be configured is desirably 10 times or more the volume average primary particle size of the particle group 36, It is desirable that it is 25 times or more. When the volume average primary particle size of the particles constituting the porous member 48 is less than 10 times the volume average primary particle size of the particle group 36, the particles pass through the gaps (pores) of the plurality of particles constituting the porous member 48. It may be difficult for the group 36 to pass. The upper limit of the volume average primary particle size of the particles constituting the porous member 48 is not particularly limited, but when the porous member 48 is configured as an aggregate of the particles, the porous member 48 and the display substrate 18 The filling rate of particles constituting the porous member 48 so that a gap (that is, a hole) having a volume average primary particle size of the particle group 36 is formed between the porous member 48 and the back substrate 20. And the number of layers to be stacked may be adjusted.

  In the present embodiment, as a method of measuring the volume average primary particle diameter of the particles constituting the particle group 36 or the particles when the porous member 48 is configured as an aggregate of particles, laser light is applied to the particle group. A laser diffraction / scattering method is employed in which the average particle size is measured from the intensity distribution pattern of the diffracted and scattered light emitted.

  Further, when the porous member 48 is constituted by a resin sheet or a nonwoven fabric, examples of the material constituting the resin sheet or the nonwoven fabric include polyethylene, polystyrene, polyester, polyacryl, polypropylene, and polytetrafluoroethylene. A fluorinated resin such as (PTFE) can be used. Particularly desirable are polypropylene and PTFE resins because the particle group 36 is difficult to adhere. When the reflecting member 38 is composed of a nonwoven fabric, the reflecting member 38 may be configured as an aggregate of fibers made of these materials.

  The porosity of the porous member 48 is preferably 50% or more and 80% or less for the reason that the passage performance through which the particle group 36 passes and the high color developability of the display medium 12 are compatible.

The average pore diameter of the pores of the porous member 48 is not particularly limited as long as the particles constituting the particle group 36 can pass through, but the average particle diameter of the particle group 36 is the volume average primary particle of the particle group 36. It is preferably in the range of 1.2 to 10,000 times the diameter, and more preferably in the range of 2 to 1000 times.
When the average pore diameter of the pores of the porous member 48 is less than 1.2 times the volume average primary particle diameter of the particle group 36, it is difficult for each particle constituting the particle group 36 to move through the hole. In some cases, exceeding 10,000 times may cause a problem that the color development is lowered due to an increase in the gap.

Further, when the porous member 48 is formed of a nonwoven fabric, the basis weight of the fibers constituting the nonwoven fabric improves the passage rate of the particle group 36 and reduces the thickness of the display medium 12. The range of / m ² or more and 100 g / m ² or less is good, and the range of 20 g / m ² or more and 50 g / m ² or less is better.

  The diameter of the fibers constituting the nonwoven fabric is in the range of 0.1 μm to 20 μm, and preferably in the range of 0.1 μm to 3 μm, to ensure a sufficient surface area and physical strength. To preferred.

The porous member 48 described above is provided with a first member 46.
The first member 46 is provided on the porous member 48, and changes to a blocked state in which the particle group 36 is prevented from passing through the pores of the porous member 48 by applying a stimulus or a released state in which the blocked state is released. To do.

  That is, when the first member 46 is blocked by the application of the stimulus, the particle group 36 becomes difficult to pass through the pores of the porous member 48, and the first member 46 is brought into the released state by the application of the stimulus. As a result, the particle group 36 can pass through the pores of the porous member 48.

  As described above, as the first member 46 that changes to the above-described blocked state by applying a stimulus, or to the above-described released state in which the blocked state is released, for example, a direction orthogonal to the thickness direction in the cell as much as possible according to the stimulus A member that opens and closes the pores of the porous member 48 when the member mechanically enters and exits, a material that swells or contracts when a stimulus is applied, a material whose charging characteristics change when a stimulus is applied, or a stimulus that is applied A member made of a material that changes to hydrophilicity or hydrophobicity can be used.

  Among these, since the configuration of the display medium 12 is a simple configuration and the passage of the particle group 36 to the pores of the porous member 48 can be easily adjusted, or the release of the inhibition can be easily adjusted, the first member As 46, it is desirable to use a member that is made of a material that swells or contracts when a stimulus is applied, a material whose charging characteristics change when a stimulus is applied, or a material that changes hydrophilic or hydrophobic when a stimulus is applied.

  First, a material that is used as the first member 46 and that swells or contracts when a stimulus is applied will be described.

  Examples of such a material that swells or contracts upon stimulation include stimulation-responsive polymer gels, shape memory polymers, and the like. Among these, the dispersion medium 42 is absorbed to swell or disperse upon application of stimulation. It is preferable to use a polymer gel that releases the medium 42 and contracts.

  The shape of the polymer gel used as the first member 46 is not particularly limited, but it is particularly preferable that the polymer gel is configured as an aggregate of a plurality of particles in consideration of stimulus response characteristics.

The form of the particles is not particularly limited, but spheres, ellipsoids, fences, rods, crushed polymorphs (polyhedrons), porous bodies, fibers, stars, needles, hollows, plates, etc. Can be used. Among these, from the viewpoint of suppressing the movement of the particle group 36, it is preferably a fence shape, a rod shape, or a pulverized polymorph. From the viewpoint of the response speed when the movement path is narrowed or widened by applying a stimulus, It is preferable that This absorbs and releases the solvent when the polymer gel undergoes a volume change. Since the shrinkage behavior starts from the surface, the density in the vicinity of the surface is increased and the solvent is hardly released. Since shrinkage occurs toward the fixed point, the higher the surface area per stretch volume, the higher the solvent release (shrinkage) rate. This is because the spherical shape is advantageous because the surface area per expansion / contraction volume is uniform compared to other shapes at any point.
In the case of a sphere, the maximum contraction distance is the diameter, but in the case of polygons or rods of the same volume, there is a high possibility that there is a part where the maximum contraction distance is longer than the diameter, and the contraction speed compared to the sphere. Becomes slower.

  The polymer gel used as the first member 46 may be provided on the surface of the porous member 48 (including the surface of the pores of the porous member 48) as a film.

  When the polymer gel is formed into particles, the particle size of the polymer gel is such that the particle group 36 is difficult to pass through the pores of the porous member 48 in the most swollen state. In the most contracted state, the size of the solution may be such that the particle group 36 can pass through the pores of the porous member 48.

  When the polymer gel is configured as a film, for example, in a state where the polymer gel is released and contracted, the pores of the porous member 48 are opened to the extent that the particle group 36 passes. In the state where the polymer gel absorbs the dispersion medium 42 and swells, the pores of the porous member 48 may be provided so as to block the particles 36 so that it is difficult for the particles to pass through. .

  Electricity, heat, or light can be used as a stimulus applied to the polymer gel to cause such a volume change.

  As the polymer gel that changes in volume by absorbing or releasing the dispersion medium 42 by applying electrical stimulation, for example, a chargeable polymer gel that causes volume change by interaction with a liquid according to an electric field is used. Here, the interaction means an action including absorption / release of a liquid accompanying a volume change of the polymer gel. Such a chargeable polymer gel is defined as an ionic polymer gel, an ionic polymer gel containing a charging agent, and a nonionic polymer gel containing a charging agent. Here, the ionic polymer gel refers to a polymer gel having an ion dissociation group in the polymer chain, and the nonionic polymer gel refers to a polymer gel having no ion dissociation group in the polymer chain.

  The charging agent is a compound that is charged by itself, and specifically includes fine particles containing an organic or inorganic ionic compound, an ionic surfactant, a coloring material described later, and the like. . The charging agent may function as a coloring material. The charging agent is fixed in the polymer gel. Specifically, fine particles and color materials containing an ionic compound are confined in a network of polymer chains constituting a polymer gel or fixed on the polymer chain. The ionic surfactant is adsorbed on the polymer chain constituting the polymer gel.

  Hereinafter, preferred specific examples of each polymer gel whose volume is changed by electrical stimulation are listed. In the description of these specific examples, the description such as “(meth) acrylate” is an expression including both “acrylate” and “methacrylate”.

<1> Ionic polymer gel Specific examples of the ionic polymer gel include cross-linked poly (meth) acrylic acid and salts thereof; (meth) acrylic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, Cross-linked products and salts of copolymers with (meth) acrylic acid alkyl esters, etc .; cross-linked products and salts of polymaleic acid; maleic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, alkyl (meth) acrylate Cross-linked products of copolymers with esters and the salts thereof; cross-linked products of polyvinyl sulfonic acid and copolymers of vinyl sulfonic acid with (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester, etc. Cross-linked product of polyvinylbenzene sulfonic acid and its salt; ) Crosslinked products and salts of copolymers with acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester, etc .; Crosslinked products and salts of polyacrylamide alkylsulfonic acid; Acrylamide alkylsulfonic acid and (meth) Cross-linked products and salts of copolymers with acrylamide, hydroxyethyl (meth) acrylate, alkyl (meth) acrylate, etc .; cross-linked polydimethylaminopropyl (meth) acrylamide and its hydrochloride; dimethylaminopropyl (meth) ) Crosslinked products and quaternized products and salts of copolymers of acrylamide with (meth) acrylic acid, (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester, etc .; polydimethylaminopropyl ( (Meth) acrylamide and poly Cross-linked product of nitryl alcohol and its quaternized product and salt; Cross-linked product and its salt of polyvinyl alcohol and poly (meth) acrylic acid; Cross-linked product of carboxyalkyl cellulose salt; Poly (meth) acrylonitrile And a partially hydrolyzed product of the cross-linked product and salts thereof.

  These ionic polymer gels are prepared by adding a cross-linking agent, or by irradiating the polymer with radiation such as electron beam or γ-ray, heating, and adding a peroxide to form a three-dimensional cross-link. can do.

<2> Ionic Polymer Gel Containing Charging Agent As the ionic polymer gel containing a charging agent, the same ionic properties as those described as specific examples of the ionic polymer gel in <1> above. A polymer gel is mentioned. On the other hand, as the charging agent to be contained in the ionic polymer gel, various amphiphilic (high) molecules, nigrosine compounds, alkoxylated amines, quaternary ammonium salts, alkylamides, phosphorus and tungsten alone and Compound, molybdenum chelate pigment, hydrophobic silica, boron, halogen compound, metal complex salt of monoazo dye, salicylic acid, alkylsalicylic acid, dialkylsalicylic acid, metal complex of naphthoic acid, chlorinated polyolefin, chlorinated polyester, polyester with excess acid group, Examples thereof include sulfonylamine of copper phthalocyanine, oil black, naphthenic acid metal salt, fatty acid metal salt, and resin acid soap.

  The addition amount of the charging agent contained in the ionic polymer gel is preferably in the range of 2% by weight to 70% by weight. The charging agent may be a color material described later.

<3> Nonionic Polymer Gel Containing Charging Agent The nonionic polymer gel containing a charging agent is a cross-linked homopolymer composed of one or more monomers selected from the monomer group listed below. And a crosslinked product of a copolymer composed of two or more monomers.

-Monomer group-
(Meth) acrylonitrile, (meth) acrylic acid alkyl ester, (meth) acrylic acid dialkylaminoalkyl ester, (meth) acrylamide, ethylene, propylene, butadiene, isoprene, isobutylene, N-dialkyl-substituted (meth) acrylamide, N-alkyl Substituted (meth) acrylamide, vinylpyridine, vinylamine, allylamine, styrene, vinylcarbazole, vinylpyrrolidone, styrene, styrene derivatives, ethylene glycol di (meth) acrylate, glyceryl (meth) acrylate, polyethylene glycol mono (meth) acrylate, vinyl chloride , Vinylidene chloride, ethylene glycol di (meth) acrylate, methylenebisacrylamide, isoprene, butadiene, ethylene glycol di (me ) Acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate.

  As the nonionic polymer gel, in addition to the (co) polymer crosslinked product consisting of the above monomer group, a polyester polymer crosslinked product, a polyvinyl acetal derivative crosslinked product, a polyurethane polymer crosslinked product, A cross-linked product of a polyurea polymer, a cross-linked product of a polyether polymer, a cross-linked product of a polyamide polymer, a cross-linked product of a polycarbonate polymer, and the like can be preferably used.

  Nonionic polymer gels are prepared by adding a crosslinking agent, or by irradiating the polymer with radiation such as electron beam or γ-ray, heating, or adding a peroxide to form a three-dimensional cross-link. be able to.

  On the other hand, examples of the charging agent contained in the nonionic polymer gel include the same charging agents as those contained in the ionic polymer gel in <2>.

  Further, the addition amount of the charging agent contained in the nonionic polymer gel is preferably in the range of 2% by weight to 70% by weight. The charging agent may be a color material described later. At this time, the preferred concentration of the coloring material contained in the nonionic polymer gel is in the range of 2% by weight to 70% by weight, and particularly preferably in the range of 5% by weight to 50% by weight.

  Further, in order to improve the responsiveness of the nonionic polymer gel to the electric field, a charging agent other than the coloring material may be separately contained in the nonionic polymer gel.

  The volume change amount of the polymer gel constituting the first member 46 is not particularly limited, but the volume change amount is preferably as high as possible, and the volume ratio during swelling and shrinking is preferably 5 or more, particularly preferably 10 or more. Further, the volume change of the polymer gel of the present embodiment is reversible.

  As a polymer gel that absorbs and releases the dispersion medium 42 by applying a light stimulus and changes its volume (swelling / shrinking), the polymer gel has a highly hydrophilic group having an ion dissociation group such as a triarylmethane derivative or a spirobenzopyran derivative. A cross-linked product of a molecular compound is preferable, and examples thereof include a cross-linked product of a copolymer of a vinyl-substituted triarylmethane leuco derivative and (meth) acrylamide, a compound having an azo group (particularly an azobenzene structure), and the like. A crosslinked product of a polymer compound having a group causing isomerization is preferred. Examples thereof include a crosslinked product of a copolymer of (meth) acryloyl group-containing azobenzene and (meth) acrylamide.

  In addition, as a polymer gel that changes volume by absorbing or releasing the dispersion medium 42 by applying thermal stimulation, LCST (lower criticality) has a property of being aggregated by a hydrophobic interaction and precipitated from an aqueous solution above a certain temperature. Polymer cross-links having eutectic temperature), polymer cross-links having UCST (upper critical eutectic temperature), polymer gels having polymer chains that are hydrogen bonded to each other, or two components that are hydrogen bonded to each other Preferred are polymer IPN bodies (interpenetrating network structures), polymer gels having cohesive side chains such as crystallinity, and the like. Among these, LCST gel using hydrophobic interaction is particularly preferable. The LCST gel shrinks at high temperature, and the UCST gel, IPN gel, and crystalline gel have a characteristic of swelling at high temperature (30 ° C. or higher).

  Specific compounds of polymer gels that shrink at high temperatures include cross-linked N-alkyl-substituted (meth) acrylamides such as poly-N-isopropylacrylamide, N-alkyl-substituted (meth) acrylamide and (meth) acrylic acid, and their Cross-linked copolymer of two or more components such as salt, (meth) acrylamide, or (meth) acrylic acid alkyl ester, crosslinked product of polyvinyl methyl ether, alkyl-substituted cellulose derivative such as methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, etc. Examples include crosslinked products. Among these, poly N-isopropyl (meth) acrylamide is preferable.

  On the other hand, as a specific compound of the polymer gel which swells at high temperature, an IPN body composed of a cross-linked body of poly (meth) acrylamide and a cross-linked body of poly (meth) acrylic acid and a partially neutralized body thereof (with acrylic acid units) (Partially salified), a crosslinked product of a copolymer mainly composed of poly (meth) acrylamide and a crosslinked product of poly (meth) acrylic acid, and a partially neutralized product thereof. More preferably, a crosslinked product of poly N-alkyl-substituted alkylamide, an IPN product of a crosslinked product of poly (meth) acrylamide and a crosslinked product of poly (meth) acrylic acid, and a partially neutralized product thereof.

  The crystalline gel includes a crosslinked product of a copolymer of (meth) acrylic acid ester and (meth) acrylic acid having a long-chain alkyl group such as octyl group, decyl group, lauryl group, stearyl group, and the like. Salt. The temperature (phase transition temperature) showing the volume change of the thermoresponsive polymer gel can be designed in various ways depending on the structure and composition of the polymer gel. The preferred phase transition temperature is preferably within the boiling point or freezing point of the solvent, more preferably in the range of −30 ° C. or more and 300 ° C. or less, still more preferably in the range of −10 ° C. or more and 150 ° C. or less. Preferably it is the range of 0 degreeC or more and 60 degrees C or less.

  In addition to the specific examples exemplified above, gels that exhibit a plurality of phase transition points according to temperature changes can be suitably used as the polymer gel that stimulates and responds to heat. Specific examples include an IPN form of a cross-linked product of polyalkyl-substituted (meth) acrylamide such as poly-N-isopropyl (meth) acrylamide and a cross-linked product of poly (meth) acrylic acid. These gels are known to exhibit two phase transition points of swelling-shrinking-swelling with increasing temperature.

  Moreover, it is also preferable to contain an ionic functional group in the polymer gel for the purpose of increasing the volume change amount of the polymer gel that is stimulated by heat. Examples of the ionic functional group include carboxylic acid, sulfonic acid, ammonium group, and phosphoric acid group. The ionic functional group copolymerizes monomers having these functional groups when preparing the gel, and impregnates the synthesized stimuli-responsive gel with the monomer to form an IPN (interpenetrating network structure) body. The functional group in the stimulus-responsive gel can be partially contained by a method such as conversion by a chemical reaction such as hydrolysis or oxidation.

  The polymer gel particles may be obtained by, for example, a method of forming a polymer gel into particles by a physical pulverization method or the like, a method of obtaining a polymer gel particle by crosslinking after polymerizing the polymer before crosslinking by a chemical pulverization method or the like, Alternatively, it can be produced by a general particle formation method such as a particle polymerization method such as an emulsion polymerization method, a suspension polymerization method or a dispersion polymerization method. Alternatively, polymer gel particles may be produced by extruding a polymer before cross-linking with a nozzle cap or the like to form a fiber, and then pulverizing the resulting polymer, or a method of pulverizing the fiber to form a particle and then cross-linking. Is possible.

  The color of the polymer gel may be any color that does not impair the reflection characteristics of the porous member 48, and is preferably transparent, for example.

Next, a material that can be used as the first member 46 and whose charging characteristics are changed by applying a stimulus will be described.
The charging characteristics are characteristics indicating the charge amount, polarity, and the like. For example, charging characteristics that change to the same polarity or non-polar state as the particle group 36, or the same polarity as the particle group 36, Examples thereof include a charging characteristic in which the charge amount changes between a charge amount less than the charge amount that does not inhibit the movement and a charge amount that inhibits the movement of the particle group 36.

  As a stimulus applied to such a material that causes a change in charging characteristics, an electrical stimulus or a light stimulus is used. Due to the ion dissociation phenomenon caused by these stimuli, the charging characteristics of the first member 46 made of the material change.

  Examples of the material whose charging characteristics are changed by applying an electrical stimulus include a conductive substance and a dielectric.

Specific examples of the conductive substance include a resin containing metal particles, a conductive polymer, a composite material in which a conductive material and a dielectric material are laminated, and the like.
Among these, it is preferable to use a composite material in which a conductive polymer or a conductive material and a dielectric material are laminated because a high change in charge amount can be obtained.

Specific examples of the dielectric include high dielectric materials such as polyester, polyethylene, polypropylene, and fluororesin.
Among these, polyester, polyethylene, and polypropylene are preferably used for reasons of durability.

  Examples of the material whose charging characteristics are changed by the application of light stimulus include a material that is ion-dissociated by light irradiation.

  An ion-cleavable photochromic compound is preferably used as a material that is ion-dissociated by light irradiation. Examples of the ion-cleavable photochromic compound include spirooxazine compounds, spiropyran compounds, and triarylmethane compounds. Can be mentioned.

  An ion-cleavage photochromic compound undergoes an ion-cleavage structure change upon application of a stimulus such as light or heat, and reversibly changes to a nonpolar state or a polar state.

  Examples of such ion-cleavable photochromic compounds include triarylmethanes, spirooxazines, spiropyrans, fulgides, indigos, stilbenes, diarylethenes and azobenzenes. In the present embodiment, those that cause an ion cleavage type change such as triarylmethanes, spirooxazines, and spiropyrans are used. In addition, complexes containing spiropyran ion-cleavage and compounds having their reverse photochromic properties can also be used. Among these, spiropyrans and triarylmethanes have high ion-cleaving properties, and also have hydroxy and cyano groups with high interaction related to hydrogen bonding and association properties, and energy such as light. This is preferably used in the present embodiment in order to cause elimination reaction and ionization associated therewith.

  The structure of a photochromic compound that is particularly preferably used in this embodiment will be exemplified. Preferable photochromic compounds include polymer materials having a structural unit represented by the following general formula (I). Such a polymer material can be obtained by homopolymerization or copolymerization with other monomers using a triarylmethane monomer represented by the following general formula (II).

(In the formula, X represents an OH group or a CN group, Y represents a carbonyl group, —NH—, — (CH ₂ ) _n — in which n is 1 or more, an ether bond, an amide bond, an ester bond, an alkylene ester) Z represents a hydrogen atom, a halogen atom or a methyl group, and R ¹ and R ² may be the same or different, and each represents a hydrogen atom, an alkyl group, an amino group, an alkylamino group, Represents an alkoxy group.)

(Substituents in the general formula (II) have the same meanings as defined in the general formula (I).)
Specific examples of monomers that can be copolymerized with triarylmethane monomers include alkyl (meth) acrylate and derivatives thereof, styrene and derivatives thereof, vinyl acetate, (meth) acrylonitrile, vinyl chloride, vinylidene chloride, and vinylpyrrolidone. , Maleic anhydride, maleimide and derivatives thereof, (meth) acrylic acid, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, meth (acrylic) amide, N, N-dimethylaminoethyl (meth) acrylate, N, Examples thereof include N-diethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, polyhydric alcohol (meth) acrylate compounds such as ethylene glycol di (meth) acrylate, and polyfunctional monomers such as vinylbenzene.

  When the triarylmethane monomer is copolymerized, the composition ratio is preferably in the range of 0.1 wt% to 90 wt% in the copolymer. The above polymer material can be synthesized by a known radical polymerization method or ionic polymerization method.

  In addition to the compound represented by the general formula (I), the photochromic compound may be a homopolymer of a triarylmethane epoxy compound, a copolymer with another epoxy compound, or a triarylmethane as a monomer. A polymer material synthesized by a condensation polymerization method can be used.

  In addition, as a low molecular weight compound as a photochromic compound, a triarylmethane compound that can be bonded by a silane coupling reaction represented by the following general formula (III), and a triarylmethane having a reactive group represented by the following general formula (VI): Examples include a reel methane compound.

(In the general formula (III), X, R ¹ and R ² have the same meanings as defined in the general formula (I). Y represents — (CH ₂ ) _n —O— wherein n is 1 or more. , — (CH ₂ ) _n — wherein n is 1 or more, — (CH ₂ ) _n —S— wherein n is 1 or more, — (CH ₂ ) _n —NH— wherein n is 1 or more, —NH— represents an ether bond, an amide bond, an ester bond, a urethane bond, or a urea bond, and a, b, and c may be the same or different, and each represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylamino group. And m represents an integer of 1 or more and 20 or less.)

(In the above formula (VI), X, R ¹ and R ² have the same meanings as defined in the general formula (I). Y is a single bond, and in — (CH ₂ ) _n —O—, n is 1 or more. things, - (CH _{2) n} - what n is 1 or more in, - (CH ₂₎ in _n -S- n is 1 or more of, - (CH ₂₎ in _n -NH- n is 1 or more -NH-, ether bond, amide bond, ester bond, urethane bond, urea bond, Z represents a single bond, alkylene group, phenylene group, substituted alkylene group, substituted phenylene group, A represents an epoxy group, aldehyde Represents an isocyanate group.)

Next, a material that can be used as the first member 46 and changes to hydrophilicity or hydrophobicity by applying a stimulus will be described.
As such a material, a material whose surface free energy changes upon application of a stimulus can be used, and as such a material whose surface free energy changes upon application of a stimulus, a halogen-containing resin such as a fluorine-based resin can be used. Can be used.
Among these, it is preferable to use a fluororesin because of a high hydrophilic / hydrophobic effect.

  This fluorine-based resin changes its surface free energy by stimulation as an electrical stimulus, and as a result, reversibly changes to hydrophobic or hydrophilic.

  As such a fluororesin, polytetrafluoroethylene, a fluororesin having tetrafluoroethylene as a structural unit, perfluoroalkoxyalkane (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin), ethylene-tetrafluoroethylene copolymer, FEP (perfluoroethylene-propene copolymer), PVdF (polyvinylidene fluoride), ECTFE (ethylene-chlorotrifluoroethylene copolymer) and the like can be mentioned. Among these, for the reason of a high hydrophilicity / hydrophobic effect, it is preferable to use a fluorine-based resin having polytetrafluoroethylene or tetrafluoroethylene as a structural unit.

  The first member 46 composed of the various materials described above is provided in a region that can form a blocking state or a releasing state in which the passage of the particle group 36 in the pores of the porous member 48 is prevented by applying a stimulus. As long as it is provided at any position of the porous member 48, specifically, either one of the porous substrate 48 described above on the display substrate 18 side and the back substrate 20 side or The form fixed to the surface of both sides may be sufficient, and the form fixed in each hole of the porous member 48 may be sufficient. Moreover, you may provide so that any one or both of the surface of each hole of the porous member 48 and the surface of area | regions other than a hole may be coat | covered.

The first member 46 can be fixed to the porous member 48 by using various bifunctional compounds and adhesives, or by using physical means.
For example, a functional group is introduced by treating the porous member 48 in advance with a reactive silane coupling agent, and reacted with a functional group of a material constituting the first member 46 (for example, a polymer gel). Immobilization and surface coating can be performed by covalent bonding or the like. In addition, a method of fixing the first member 46 by chemical bonding (ionic bonding, hydrogen bonding) with various polyfunctional compounds and adhesives, or the surface of the porous member 48 is processed to form the first member 46. Can also be physically immobilized.

In the present embodiment, the case where the reflecting member 38 has a configuration in which the first member 46 is provided on the porous member 48 will be described. However, the porous member 48 and the first member 46 are integrally formed. The provided structure may be sufficient.
In this case, for example, the first member 46 has the property of changing to the blocked state or the released state in which the passage of the particle group 36 to the hole is prevented by applying a stimulus as described above, and further the particle group. What is necessary is just to set it as the structure which has the characteristic demonstrated as the characteristic of the said porous member 48, such as a magnitude | size of a hole, a porosity, thickness, a refractive index, a color, etc. which has a reflective characteristic different from 36. When the reflecting member 38 is configured such that the porous member 48 and the first member 46 are integrally provided, the size of the hole and the porosity of the reflecting member 38 are in the released state. The pore size and the porosity at a certain time may be within the range of the pore size and the porosity of the porous member 48 described above.

-Dispersion medium-
The dispersion medium 42 is preferably an insulating liquid.

  Specific examples of the insulating liquid include hexane, cyclohexane, toluene, xylene, decane, hexadecane, kerosene, paraffin, isoparaffin, silicone oil, dichloroethylene, trichloroethylene, perchloroethylene, high-purity petroleum, ethylene glycol, and alcohols. , Ethers, esters, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, 2-pyrrolidone, N-methylformamide, acetonitrile, tetrahydrofuran, propylene carbonate, ethylene carbonate, benzine, diisopropylnaphthalene, olive oil, isopropanol, trichloro Trifluoroethane, tetrachloroethane, dibromotetrafluoroethane, etc. and mixtures thereof are preferred. It can be used for.

Moreover, water (so-called pure water) can also be suitably used as a dispersion medium by removing impurities so as to have the following volume resistance value. The volume resistance value is preferably 10 ³ Ωcm or more, more preferably 10 ⁷ Ωcm or more and 10 ¹⁹ Ωcm or less, and further preferably 10 ¹⁰ Ωcm or more and 10 ¹⁹ Ωcm or less. By setting such a volume resistance value, the generation of bubbles due to the electrolysis of the liquid due to the electrode reaction is more effectively suppressed, and the electrophoretic characteristics of the particles are not impaired every time energization is achieved. Repeatable 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.
It has ionic and nonionic surfactants, block or graft copolymers consisting of lipophilic and hydrophilic parts, and also has a polymer chain skeleton such as cyclic, star-like, and dendritic polymers (dendrimers). Further, a compound selected from a metal complex of salicylic acid, a metal complex of catechol, a metal-containing bisazo dye, a tetraphenylborate derivative and the like can be used.
Is given.

  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.

  Further, the viscosity of the dispersion medium 42 is in the range of 0.1 mPa · s to 20 mPa · s in an environment at a temperature of 20 ° C. from the viewpoint of the moving speed of the particle group 36 and hence the display speed. It is preferably 1 mPa · s or more and 5 mPa · s or less, and more preferably 0.1 mPa · s or more and 2 mPa · s or less.

  For example, as shown in FIG. 3, the display medium 12 configured as described above swells as a first member 46 in a hole of a porous member 48 </ b> A that is one mode of the porous member 48 by applying a stimulus. Alternatively, if the shrinking particulate polymer gel 46A is fixed, the polymer gel 46A absorbs the dispersion medium 42 by applying a stimulus and swells so as to close the hole 44 of the porous member 48A. Thus, the polymer gel 46A enters a blocking state in which the particle group 36 prevents the passage of the holes 44. In this blocking state, as shown in FIG. 3A, the passage of the particle group 36 enclosed in each cell of the display medium 12 to the hole 44 is blocked.

  On the other hand, by applying the stimulus, the polymer gel 46A shrinks by releasing the dispersion medium 42 and shrinks so as to release the holes 44 from the swollen state so as to close the holes 44 of the porous member 48A. The molecular gel 46A is in a released state where the blocked state is released. In this released state, as shown in FIG. 3 (B), the holes 44 of the porous member 48A are released to the extent that the particle group 36 can pass through, and the particle group 36 has the holes of the porous member 48A. 44 can pass through.

  Further, for example, as shown in FIG. 4, the first member 46 swells or contracts due to the application of a stimulus to the surface of the hole 44 of the mesh-like porous member 48B which is one embodiment of the porous member 48. In the case where the molecular gel 46B is provided, the polymer gel 46B absorbs the dispersion medium 42 by applying a stimulus and swells so as to close the holes 44 of the porous member 48B, as shown in FIG. In addition, the polymer gel 46B is in a blocking state in which the movement of the inside of the hole 44 by the particle group 36 is blocked. In this blocking state, as shown in FIG. 4A, the passage of the holes 44 of the particle group 36 is blocked.

  On the other hand, by applying the stimulus, the polymer gel 46B shrinks by releasing the dispersion medium 42 and shrinks so as to release the holes 44 from the swollen state so as to close the holes 44 of the porous member 48B. The molecular gel 46B is released. In this released state, as shown in FIG. 4B, the particle group 36 is in a state where it can pass through the holes 44.

  Further, for example, as shown in FIG. 5, the first member 46 is coated with a stimulus so as to cover the surface of the hole 44 of the mesh-like porous member 48 </ b> C that is one embodiment of the porous member 48. In the case of the configuration in which the first member 46C whose charging characteristics change is provided, for example, if the particle group 36 is precharged to the positive electrode, for example, the charging of the first member 46C by applying a stimulus is performed. When the characteristics change and the positive polarity is charged from the nonpolar state to the positive polarity having the same polarity as the particle group 36, or the positive polarity (same polarity as the particle group 36) is difficult to prevent the movement of the particle group 36. As shown in FIG. 5A, by changing from the state of charge amount to the state of charge amount of positive charge that prevents the movement of the particle group 36 (charge amount increases), The first member 4 by electric repulsion C is a blocking state for blocking the passage of the bore 44 by particles 36. In this blocking state, as shown in FIG. 5A, the passage of the particle group 36 through the hole 44 is blocked.

  On the other hand, by applying the stimulus, the charging characteristic of the first member 46C is changed to change from the positive polarity having the same polarity as the particle group 36 to the non-polar state, or the movement of the particle group 36 is prevented. As shown in FIG. 5B, the state changes from a state having a positive charge amount to a state where the amount of charge is difficult to prevent the movement of the particle group 36 (a decrease in the charge amount). The first member 46 </ b> C is in a released state in which the blocking state for preventing the particle group 36 from passing through the hole 44 is released. In this released state, as shown in FIG. 5B, the particle group 36 is in a state where it can pass through the holes 44 of the porous member 48C.

  Although illustration is omitted, the same applies to the case where the surface of the hole 44 of the porous member 48 is provided with a material whose surface free energy changes as a result of the application of the stimulus as the first member 46. When the surface free energy of the first member 46 changes due to the application and the first member 46 changes from hydrophilic to hydrophobic, the first member 46 becomes porous due to the particles 36 that are hydrophilic due to electrical repulsion. A blocking state for blocking the passage in 44 is obtained. In this blocking state, passage of the particle group 36 through the hole 44 is blocked.

  On the other hand, when the surface free energy of the first member 46 changes due to the application of the stimulus and the first member 46 changes from hydrophobic to hydrophilic, the first member 46 has pores formed by the particle groups 36 that are hydrophilic. 44 is a release state in which the blocking state for blocking the passage in 44 is released. In this released state, the particle group 36 is allowed to pass through the hole 44.

Therefore, as shown in FIG. 1, when the particle group 36 is located on the display substrate 18 side from the reflecting member 38 of the display medium 12, or as shown in FIG. When the first member 46 is stimulated to be in a blocking state when it is positioned on the back substrate 20 side with respect to the reflecting member 38, FIGS. As shown in A) and FIG. 5A, the first member 46 changes to the blocking state. When the first member 46 is in the blocking state, it becomes difficult for the particle group 36 to pass through the hole 44 of the porous member 48.
Then, when a stimulus for changing the first member 46 from the blocked state to the released state is applied to the first member 46, FIG. 3 (B), FIG. 4 (B), and FIG. 5 (B). As shown, the first member 46 changes to a released state. When the first member 46 is in the released state, the particle group 36 is a porous member 48 (in this embodiment, when the porous member 48A, the porous member 48B, and the porous member 48C are collectively referred to as Similarly, the first member 46 is a generic term for the polymer gel 46A, the polymer gel 46B, and the first member 46C, which are one mode of the first member 46. In this case, it is referred to as the first member 46.) and can pass through the hole 44.

As described above, in the display medium 12 of the present embodiment, the blocked state in which the particle group 36 is prevented from passing through the hole 44 of the porous member 48 or the blocked state is released by applying the stimulus. A first member 46 that changes to the released state is provided in the porous member 48.
Therefore, when the first member 46 is in the released state, an electric field that moves the particle group 36 toward the display substrate 18 or the back substrate 20 is formed between the display substrate 18 and the back substrate 20, After the electric field is formed, a stimulus for blocking the first member 46 is applied to the first member 46, whereby an electric field is formed between the display substrate 18 and the back substrate 20. Thus, the particle group 36 that has moved to the display substrate 18 side or the back substrate 20 side is held on the substrate side that has moved, and can move to the opposite substrate side (the back substrate 20 side or the display substrate 18 side). Be blocked.

  Accordingly, it is possible to suppress a decrease in image quality retention of the display medium 12.

  In addition, since the first member 46 is provided on the porous member 48 or the first member 46 and the porous member 48 are integrally formed, the reflectance and durability as the reflective layer are provided. In addition, there is an effect that the contrast of migration of particles is high and the contrast of release is high.

(Second Embodiment)
As shown in FIG. 7, the display device 10 according to the present embodiment includes a voltage application unit 14, an image information acquisition unit 17, a control unit 16, and the display medium 12 described in the first embodiment. It is configured to include. The voltage application unit 14 and the image information acquisition unit 17 are connected to the control unit 16 so as to be able to exchange signals.

Since the configuration of the display medium 12 has been described in the first embodiment, the same function is assigned the same number and detailed description thereof is omitted.
Further, the first member 46 provided in the display medium 12 in the present embodiment is in a blocking state in which the particle group 36 is prevented from passing through the hole 44 of the porous member 48 or in a released state in which the blocking state is released. The case where an electrical stimulus is used as the stimulus for changing will be described.
Therefore, the material constituting the first member 46 used in the second embodiment is blocked by electrical stimulation among the materials constituting the first member 46 described in the first embodiment. A material that changes to a state or a released state is used.

  The voltage application unit 14 is connected to the control unit 16 so as to be able to send and receive signals, and is connected to the front electrode 24 and the back electrode 30 so that voltage can be applied.

  The image information acquisition unit 17 acquires image information indicating an image to be displayed on the display medium 12 from the outside of the display device 10. As the image information acquisition unit 17, for example, a CD-R, FD (floppy (registered trademark) disk) ), A general reader for reading image information recorded on the image recording medium from an image recording medium such as MD, DVD, etc., or a general for acquiring image information via a wireless or wired communication network A communication device or the like can be used.

  The control unit 16 controls the voltage applied from the voltage application unit 14 to the display medium 12 according to the image information acquired by the image information acquisition unit 17. The control unit 16 includes a microcomputer including a CPU 16A, a ROM 16B, a RAM 16C, and a hard disk (not shown). The CPU 16A displays an image on the display medium 12 according to a program stored in the ROM 16B, a hard disk, or the like.

  Below, the process performed by CPU16A of the control part 16 of the display apparatus 10 provided with the display medium 12 in this Embodiment is demonstrated.

  The CPU 16A of the control unit 16 reads the program shown by the processing routine shown in FIG. 8 from the ROM 16B or the hard disk in the control unit 16 to execute the process shown in FIG.

In the present embodiment, in order to simplify the description, the image information acquisition unit 17 acquires information indicating the color of the image displayed in one specific cell of the display medium 12 as the image information. A case where a color based on the image information is displayed in one corresponding cell of the display medium 12 will be described.
Further, before execution of the processing routine shown in FIG. 8, it is assumed that almost all of the particle groups 36 in the cell are located on the display substrate 18 side as shown in FIG.
Note that “substantially all” means that there are variations in the characteristics of the particle group 36, and therefore some of the characteristics of the particles are different to the extent that they do not contribute to the display characteristics.
Further, the particle group 36 in the cell has the voltage range described in the first embodiment that moves between the substrates, and a voltage within the voltage range is a driving voltage having a predetermined value within the voltage range. Will be described on the assumption that the particle group 36 is charged on the positive electrode.

Furthermore, in the present embodiment, the first member 46 applies an electric field between the display substrate 18 and the back substrate 20 by applying a voltage to the front electrode 24 and the back electrode 30 as electrical stimulation. A description will be given on the assumption that when formed, a change in volume, a change in charging characteristics, or a change in surface free energy occurs to cause the release state, and when the voltage application is stopped, the change from the release state to the blocking state occurs. In the following description, it is assumed that the drive voltage is determined as a voltage value within the range of the voltage as the electrical stimulation.
In the first member 46, a value less than the absolute value of the voltage range in which the particle group 36 moves is determined as the voltage value of the electrical stimulation applied to change from the blocking state to the release state. Will be described. That is, in the present embodiment, the first member 46 is changed from the released state to the blocked state by applying a voltage higher than a voltage value less than the voltage range in which the particle group 36 moves in the same cell. However, a material that changes from a released state to a blocked state when the voltage application is released is used.
Specifically, for example, when a voltage in the range of + mV to + nV (m <n) and a voltage in the range of −mV to −nV are applied between the substrates, the particle group 36 is displayed. When moving between the substrate 18 and the back substrate 20, the first member 46 changes from a blocking state to a release state by applying a voltage of | sV | A material that changes from the released state to the blocked state by releasing the application may be used.

The CPU 16A of the control unit 16 executes the processing routine shown in FIG.
In step 100, it is determined whether or not the image information acquisition unit 17 has acquired the image information. If the determination is negative, this routine is terminated. If the determination is positive, the process proceeds to step 102.

In step 102, the color information included in the image information acquired in step 100 is read.
In the next step 104, a voltage lower than the voltage at which the particle group 36 moves, that is, a voltage that does not cause the particle group 36 to move, is applied to the cell that displays the color of the color information read in step 102. The signal is output to the voltage application unit 14. By accepting the signal, the voltage application unit 14 sets a voltage having a voltage value such that the particle group 36 in the cell does not move into the cell that displays the color of the color information read in step 102. Applied to the surface electrode 24 and the back electrode 30. In addition, the polarity of the voltage at this time may be a positive electrode or a negative electrode.

  In the process of step 104, for example, when the absolute value of the minimum value of the voltage range in which the particle group 36 moves is, for example, | mV | shown in FIG. 2, by receiving a signal from the control unit 16 The voltage application unit 14 begins to apply a voltage lower than | mV | to the front electrode 24 and the back electrode 30 so that one of the front electrode 24 and the back electrode 30 is a positive electrode and the other is a negative electrode.

  By the processing in step 104, an electric field that does not cause movement of the particle group 36 is formed between the display substrate 18 and the back substrate 20, and electrical stimulation is applied to the first member 46. The first member 46 changes from the blocked state to the released state by applying electrical stimulation. Therefore, the particle group 36 can pass through the hole 44 of the porous member 48 as shown in FIGS. 3B, 4B, and 5B described in the first embodiment. It becomes a state.

  In the next step 106, the predetermined time previously stored in the ROM 16A or the hard disk or the like in the control unit 16 is read, and negative determination is repeated until the predetermined time elapses after the voltage application is started in the process of step 104, If the determination is affirmative, the routine proceeds to step 108.

As the “predetermined time” in the process of step 106, a time required for the first member 46 to change from the closed state to the released state by the application of the electrical stimulus by the process of step 104 may be set in advance. .
For example, when the first member 46 is a polymer gel that contracts by releasing the dispersion medium 42 by applying electrical stimulation, the polymer is applied when a voltage having a voltage value obtained by the process of step 104 is applied. The time required for the gel to absorb the dispersion medium 42 and swell up to the minimum swelled state (blocking state) to release the dispersion medium 42 to the minimum shrinkable state (released state) is set in advance. do it. This time may be measured in advance and stored in advance in the ROM or hard disk in the control unit 16.

  Note that the “maximum swollen state” indicates a state in which the volume does not swell and does not swell even if a stimulus is applied after the start of swelling. In addition, the “minimum contracted state” indicates a state in which no contraction occurs even after further stimulation and no volume change occurs.

  By performing the processing of step 104 and step 106, the first member 46 changes to a released state in which the particle group 36 can pass through the hole of the porous member 48. Is in a state in which the particle group 36 can pass through.

In the next step 108, a signal indicating that the drive voltage of the particle group 36 is applied between the surface electrode 24 and the back electrode 30 with a polarity corresponding to the color information read in the step 102 is applied to the voltage. Output to the application unit 14.
By receiving the signal, the voltage application unit 14 starts applying the drive voltage with the front electrode 24 as a negative electrode and the back electrode 30 as a positive electrode, for example.

  In the next step 110, the set time stored in advance in the ROM 16B or the hard disk in the control unit 16 is read, and negative determination is repeated until the set time elapses after the voltage application is started in the process of step 104. If the result is affirmative, the routine proceeds to step 112.

  As the “set time” in the process of step 110, the particle group 36 in the cell displays in advance from the display substrate 18 side to the back substrate 20 side or the back substrate 20 side when the drive voltage is applied in step 108. What is necessary is just to measure and set beforehand the time required for the movement to the board | substrate 18 side. This time may be measured in advance and stored in advance in the ROM 16B in the control unit 16 or the hard disk.

  Through the processing of Step 108 and Step 110, the particle group 36 (see FIG. 1) located on the display substrate 18 side reaches the back substrate 20 side through the hole 44 of the porous member 48 (see FIG. 9). ). That is, the first member 46 is in the released state and the particles constituting the particle group 36 are in a state that can pass through the holes 44 of the porous member 48 by the processing of step 104 and step 106 described above. As a result of the processing in step 110, the particle group 36 moves between the substrates through the holes 44 of the porous member 48.

  In the next step 112, a signal indicating the stop of voltage application to the front electrode 24 and the back electrode 30 is output to the voltage application unit 14. When the signal is received, the voltage application unit 14 terminates the present routine after stopping the voltage application to the front electrode 24 and the back electrode 30.

  When the application of voltage to the front electrode 24 and the back electrode 30 is stopped by the process of step 112, the first member 46 that has been released by the process of step 104 to step 110 changes to the blocking state. For this reason, the movement of the particle group 36 through the hole 44 of the porous member 48 is prevented by the process of step 112, and the particle group 36 that has moved to the back substrate 20 side by the process of step 108 is Is prevented from moving to the display substrate 18 side, and is held on the back substrate 20 side.

  On the other hand, in the same manner when the processing of step 100 to step 112 is performed so that the particle group 36 is located on the display substrate 18 side from the state located on the rear substrate 20 side, The particle group 36 that has moved from the substrate 20 side to the display substrate 18 side is held on the moved display substrate 18 side.

Thus, the particle group 36 moved to the display substrate 18 side or the back substrate 20 side according to the image displayed on the display medium 12 can be held on the moved substrate side by the first member 46. .
Therefore, according to the display device 10 of the present embodiment, it is possible to suppress a decrease in image quality retention of the display medium 12.

  In the present embodiment, a case has been described in which a material that changes to a blocked state or a released state by electrical stimulation is used as the first member 46 and electrical stimulation is used as the stimulation. When electrical stimulation is used as a stimulus for changing 46 to the blocked state or the released state, the voltage application unit 14 that applies a voltage between the substrates to move the particle group 36 is replaced with the first member 46. It can also be used as a device for applying a stimulus for changing to a blocking state or a release state, and there is no need to separately provide a device for applying a stimulus to the first member 46. The configuration can be simplified and the configuration of the display medium 12 can also be simplified.

  In the present embodiment, as a device for applying electrical stimulation to the first member 46, the voltage application unit 14 for applying a voltage to the front electrode 24 and the rear electrode 30 of the display medium 12 is used. However, it is not limited to such a configuration.

  For example, as shown in FIG. 10, the display device 11 may include a display medium 12, a voltage application unit 14, a control unit 16, an image information acquisition unit 17, and a voltage application unit 50. Since the display device 11 shown in FIG. 10 has substantially the same configuration as the display device 10, the same parts are denoted by the same reference numerals and detailed description thereof is omitted.

  The voltage application unit 14, the control unit 16, the image information acquisition unit 17, and the voltage application unit 50 are connected to the control unit 16 so that signals can be exchanged.

  In this case, a conductive porous member 48 is used as the porous member 48 constituting the reflecting member 38 of the display medium 12, and the porous member 48 is changed to a blocking state or a releasing state by electrical stimulation. The first member 46 may be provided, and the porous member 48 may be connected to the voltage application unit 50 so as to be able to exchange signals.

  Then, in the CP 16A of the control unit 16, the first member 46 is released to the voltage application unit 50 instead of the signal output process indicating the voltage application start to the voltage application unit 14 in the process of step 104 described in FIG. The above diagram is output except that a signal indicating the start of voltage application for setting the state is output, and a signal indicating a voltage application stop is output to both the voltage application unit 14 and the voltage application unit 50 in place of the process of step 112 above. The processing routine shown in FIG.

  With such a configuration, it is possible to directly apply a stimulus for bringing the first member 46 provided on the porous member 48 into the blocking state or the releasing state, to the porous member 48. Display speed can be improved.

(Third embodiment)
In the second embodiment, the display device 10 that displays an image on the display medium 12 using a material that changes to a blocked state or a released state by electrical stimulation as the first member 46 has been described. In the embodiment, a display device 60 that displays an image on the display medium 12 using, as the first member 46, a material that changes to a blocked state or a released state by heat stimulation will be described.

  In the display device 60 according to the present embodiment, the same parts as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 11, the display device 60 according to the present embodiment includes a display medium 12, a voltage application unit 14, a control unit 68, an image information acquisition unit 17, and a heating member 66. ing. The voltage application unit 14, the image information acquisition unit 17, and the heating member 66 are connected to the control unit 68 so as to be able to exchange signals.

When the heating member 66 receives a signal indicating a heat generation instruction from the control unit 68, the heating member 66 is a member for applying heat to the first member 46 so as to reach a temperature corresponding to the signal.
Specific examples of the heating member 66 include silicon rubber heater, aluminum foil heater, aluminum foil rubber heater, saw-in cloth heater, carbon heater, cord heater, belt heater, sheath heater, straight sheath heater, line heater, hopper heater, A coil heater, a cartridge heater, etc. are mentioned.

  In the present embodiment, the heating member 66 is described as being provided separately from the display medium 12, but the heating member 66 may be provided integrally with the display medium 12.

The first member 46 provided in the display medium 12 in the present embodiment changes to a blocking state in which the particle group 36 is prevented from passing through the hole 44 of the porous member 48 or a released state in which the blocking state is released. A case will be described where thermal stimulation is used as the stimulation.
For this reason, as a material which comprises the 1st member 46 used by 2nd Embodiment, the material which changes to a blocking state or a cancellation | release state by the thermal stimulation demonstrated in the said 1st Embodiment is used.

  In the present embodiment, the first member 46 made of a material that changes to a blocking state or a released state by this thermal stimulation is equal to or higher than a predetermined phase transition temperature determined according to the material constituting the first member 46. If the heat of less than the phase transition temperature is applied, the state changes to the release state.

  The control unit 68 controls the voltage applied from the voltage application unit 14 to the display medium 12 according to the image information acquired by the image information acquisition unit 17 and controls the heating member 66 to generate heat. The control unit 68 includes a microcomputer including a CPU 68A, a ROM 68B, a RAM 68C, and a hard disk. The CPU 68A displays an image on the display medium 12 according to the program shown in FIG. 12 stored in the ROM 68B, the hard disk, or the like.

  Below, the process performed by the control part 68 of the display apparatus 60 provided with the display medium 12 in this Embodiment is demonstrated.

  The CPU 68A of the control unit 68 executes the processing shown in FIG. 12 by reading the program shown by the processing routine shown in FIG. 12 from the ROM 68B or the hard disk of the control unit 68.

In the present embodiment, in order to simplify the description, the image information acquisition unit 17 acquires information indicating the color of the image displayed in one specific cell of the display medium 12 as the image information. A case where a color based on the image information is displayed in one corresponding cell of the display medium 12 will be described.
In order to simplify the description, it is assumed that all the particle groups 36 in the cell are located on the display substrate 18 side before the processing routine shown in FIG. 12 is executed.
Further, the particle group 36 in the cell has the voltage range described in the first embodiment that moves between the substrates, and a voltage within the voltage range is a driving voltage having a predetermined value within the voltage range. Will be described on the assumption that the particle group 36 is charged on the positive electrode.
In addition, it is assumed that the phase transition temperature is measured in advance as a temperature for changing the first member 46 from the blocked state to the released state.

In the CPU 68A of the control unit 68, the processing routine shown in FIG.
In step 200, it is determined whether or not the image information acquisition unit 17 has acquired image information. If the determination is negative, this routine is terminated. If the determination is affirmative, the process proceeds to step 202.

In step 202, color information included in the image information acquired in step 200 is read.
In the next step 204, a signal indicating that the first member 46 in the cell that is the target of displaying the color information color read in step 202 is heated to a temperature exceeding the phase transition temperature is sent to the heating member 66. Output.

The heating member 66 that has received the signal generates heat to a temperature corresponding to the signal when the heating element generates heat, and starts to heat the first member 46 to a temperature exceeding the phase transition temperature.
By the process of step 204, thermal stimulation is applied to the first member 46, and the first member 46 begins to change from the blocked state to the released state.

  In the next step 206, a predetermined time stored in advance in the ROM 68B or the hard disk in the control unit 68 is read, and a negative determination is repeated until the predetermined time has elapsed since the heating process was started in the process of step 204, If the determination is affirmative, the routine proceeds to step 208.

  As the “predetermined time” in the process of step 208, the time until the first member 46 in the cell changes from the blocked state to the released state may be measured in advance. For example, the first member 46 is released by contracting by releasing the dispersion medium 42 due to thermal stimulation caused by a temperature exceeding the phase transition temperature, and is lower than the phase transition temperature (for example, a predetermined value from the phase transition temperature). In the case of a polymer gel that is blocked by absorbing and swelling the dispersion medium 42 by thermal stimulation (lower than the temperature), this polymer gel can swell by absorbing the dispersion medium 42 by thermal stimulation. What is necessary is just to set beforehand the time until it discharge | releases the dispersion medium 42 from the largest swelled state and it becomes the minimum shrinkable state which can be shrunk. This time may be measured in advance and stored in advance in the ROM 68B in the control unit 68 or in the hard disk.

  Since the first member 46 is released by executing the processing of the above step 204 and step 206, the hole 44 of the porous member 48 is such that each particle constituting the particle group 36 can move. It is in a released state.

In the next step 208, a signal indicating that the drive voltage is applied between the front electrode 24 and the back electrode 30 with a polarity corresponding to the color information read in step 202 is output to the voltage application unit 14.
By receiving the signal, the voltage application unit 14 starts applying the drive voltage with the front electrode 24 as a negative electrode and the back electrode 30 as a positive electrode, for example.

  In the next step 210, the set time stored in advance in the ROM 68B or hard disk in the control unit 68 is read, and negative determination is repeated until the set time elapses after the voltage application is started in the processing of step 208. If the result is affirmative, the routine proceeds to step 212.

  As the “set time” in the process of step 210, the particle group 36 in the cell moves in advance from the display substrate 18 side to the back substrate 20 side or from the back substrate 20 side to the display substrate 18 side by applying a driving voltage. What is necessary is just to measure and set beforehand the time required for this. This time may be measured in advance and stored in advance in the ROM 68B in the control unit 68 or in the hard disk.

  Through the processing of Step 208 and Step 210, the particle group 36 (see FIG. 1) located on the display substrate 18 side reaches the back substrate 20 side through the hole 44 of the porous member 48 (see FIG. 13). ).

  In the next step 212, a signal indicating stoppage of voltage application to the front electrode 24 and the back electrode 30 is output to the voltage application unit 14. When the signal is received, the voltage application unit 14 stops the voltage application to the front electrode 24 and the back electrode 30.

  In the next step 214, after outputting a signal indicating the heating stop to the heating member 66, this routine is finished.

  When the heating by the heating member 66 is stopped by the process of step 214, the first member 46 that has been released by the process of step 204 and step 206 changes to the blocking state. For this reason, the movement of the particle group 36 to the hole 44 of the porous member 48 is blocked by the first member 46 by the process of step 214, and the particle group 36 that has moved to the back substrate 20 side by the process of step 208 is The movement from the back substrate 20 side to the display substrate 18 side is blocked by the first member 46 and is held on the back substrate 20 side.

  On the other hand, in the same manner when the processing of Step 200 to Step 214 is performed so that the particle group 36 is located on the display substrate 18 side from the state located on the rear substrate 20 side, The particle group 36 that has moved from the substrate 20 side to the display substrate 18 side is held on the moved display substrate 18 side.

  Specifically, after the particle group 36 located on the back substrate 20 side reaches the display substrate 18 side through the hole 44 of the porous member 48 provided with the released first member 46, The first member 46 changes to the blocking state. Accordingly, the particle group 36 that has moved to the display substrate 18 side is prevented from moving to the back substrate 20 side, and is held on the display substrate 18 side.

  For this reason, it is possible to suppress a decrease in image quality retention of the display medium 12.

(Fourth embodiment)
In the second embodiment and the third embodiment, as the first member 46, the display device 10 that displays an image on the display medium 12 using a material that changes to a blocked state or a released state by electrical stimulation. Each of the display device 10 and the display device 60 that displays an image on the display medium 12 using a material that changes to a blocked state or a released state by thermal stimulation has been described. In the present embodiment, the blocked state is caused by light stimulation. Or the display apparatus 70 which displays an image on the display medium 12 using the material which changes to a cancellation | release state as the 1st member 46 is demonstrated.

  The display device 70 according to the present embodiment is described in detail by assigning the same reference numerals to the same portions as those in the first embodiment, the second embodiment, and the third embodiment. Is omitted.

  As shown in FIG. 14, the display device 70 according to the present embodiment includes a display medium 12, a voltage application unit 14, a control unit 68, an image information acquisition unit 17, and a light stimulus application unit 76. It is configured.

  The control unit 78 is electrically connected to the back electrode 30, the surface electrode 24, and the voltage application unit 14. The control unit 78 is connected to the voltage application unit 14, the light stimulus application unit 76, and the image information acquisition unit 17 so as to exchange signals.

When receiving a light emission instruction and a signal indicating the wavelength and light amount of light to be emitted from the control unit 78, the light stimulus applying unit 76 irradiates the first member 46 with light having a wavelength and light amount corresponding to the signal.
Examples of the light stimulus applying unit 76 include a surface emitting LED, various surface emitting lamps (including UV, visible light, and infrared), a surface emitting semiconductor laser, an organic EL, and an inorganic EL.

  In the present embodiment, the case where the light stimulus applying unit 76 is provided as a separate body from the display medium 12 will be described. However, a configuration in which the light stimulus applying unit 76 is provided integrally with the display medium 12 may be used.

The first member 46 provided in the display medium 12 in the present embodiment changes to a blocking state in which the particle group 36 is prevented from passing through the hole 44 of the porous member 48 or a released state in which the blocking state is released. A case in which a light stimulus is used as the stimulus of will be described.
For this reason, as a material which comprises the 1st member 46 used by this Embodiment, the material which changes to a blocking state or a cancellation | release state by the light stimulus demonstrated in the said 1st Embodiment is used.

  In the present embodiment, the first member 46 made of a material that changes to a blocking state or a released state by this light stimulation is equal to or greater than a predetermined reference light amount determined according to the material constituting the first member 46. The description will be made assuming that when light is irradiated, the state changes to the blocking state, and in the state where light less than the reference light amount is added, the state changes to the release state.

Note that the conditions of this light stimulation vary depending on the material used as the first member 46, and are not limited to the amount of light. It is also possible to use a material that changes to a released state (or blocked state) when irradiated with light (for example, an ultraviolet region) in a wavelength region different from the specific wavelength region.
In this case, in the processing routine shown in FIG. 15 to be described later, as light stimulation for bringing the first member 46 into the blocking state or the releasing state, light in a wavelength region corresponding to the target state is irradiated. Control may be performed as follows.

  The control unit 78 controls the voltage applied from the voltage application unit 14 to the display medium 12 according to the image information acquired by the image information acquisition unit 17 and controls the light emission of the light stimulus applying unit 76. The control unit 78 includes a microcomputer including a CPU 78A, a ROM 78B, a RAM 78C, a hard disk, and the like. The CPU 78A displays an image on the display medium 12 according to the program shown in FIG. 15 stored in the ROM 78B, the hard disk, or the like.

  Below, the process performed by the control part 78 of the display apparatus 70 provided with the display medium 12 in this Embodiment is demonstrated.

  The CPU 78A of the control unit 78 executes the processing shown in FIG. 15 by reading the program shown by the processing routine shown in FIG. 15 from the ROM 78B or the hard disk of the control unit 78.

In the present embodiment, in order to simplify the description, the image information acquisition unit 17 acquires information indicating the color of the image displayed in one specific cell of the display medium 12 as the image information. A case where a color based on the image information is displayed in one corresponding cell of the display medium 12 will be described.
Further, before execution of the processing routine shown in FIG. 15, it is assumed that almost all of the particle groups 36 in the cell are located on the display substrate 18 side as shown in FIG.
Further, the particle group 36 in the cell has the voltage range described in the first embodiment that moves between the substrates, and a voltage within the voltage range is a driving voltage having a predetermined value within the voltage range. Will be described on the assumption that the particle group 36 is charged on the positive electrode.
Further, a description will be given assuming that the reference light amount is measured in advance as the light amount of the light stimulus for changing the first member 46 from the blocked state to the released state.

In the CPU 78A of the control unit 78, the processing routine shown in FIG.
In step 300, it is determined whether or not the image information acquisition unit 17 has acquired image information. If the determination is negative, the routine ends. If the determination is affirmative, the process proceeds to step 302.

In step 302, the color information included in the image information acquired in step 300 is read.
In the next step 304, a signal indicating that the first member 46 in the cell to be displayed with the color information read in step 302 is irradiated with light having a light amount equal to or greater than the reference light amount is provided with a light stimulus. To the unit 76.

The light stimulus imparting unit 76 that has received the signal irradiates the first member 46 with a light amount corresponding to the signal.
By the process of step 304, the first member 46 starts to change from the blocked state to the released state.

  In the next step 306, the predetermined time stored in advance in the ROM 78B or the hard disk in the control unit 78 is read, and negative determination is repeated until the predetermined time has elapsed since the start of light irradiation in the process of step 304, If affirmed, the process proceeds to step 308.

  As the “predetermined time” in the process of step 308, a time until the material constituting the first member 46 in the cell changes from the blocked state to the released state may be set in advance. For example, when the first member 46 is a polymer gel that swells or contracts by light stimulation, the polymer gel absorbs the dispersion medium 42 by the light stimulation irradiation and can swell to the maximum extent. The time from when the dispersion medium 42 is released from the state to the minimum contractible state that can be contracted may be set in advance. This time may be measured in advance and stored in advance in the ROM 78B in the control unit 78 or the hard disk.

  Since the first member 46 is changed from the blocked state to the released state by executing the processing of the above step 304 and step 306, the particle group 36 is movable through the hole 44 of the porous member 48. It becomes.

In the next step 308, a signal indicating that a drive voltage is applied between the front electrode 24 and the back electrode 30 is output to the voltage application unit 14 with a polarity corresponding to the color information read in step 302.
By receiving the signal, the voltage application unit 14 starts applying the drive voltage with the front electrode 24 as a negative electrode and the back electrode 30 as a positive electrode, for example.

  In the next step 310, the set time stored in advance in the ROM 78B or the hard disk in the control unit 78 is read, and negative determination is repeated until the set time elapses after the voltage application is started in the process of step 308. If the result is affirmative, the routine proceeds to step 312.

  As the “set time” in the process of step 310, the particle group 36 in the cell displays in advance from the display substrate 18 side to the back substrate 20 side or from the back substrate 20 side when the drive voltage in step 308 is applied. What is necessary is just to measure and set beforehand the time required for the movement to the board | substrate 18 side. This time may be measured in advance and stored in advance in the ROM 78B in the control unit 78 or the hard disk.

  By the processing of Step 308 and Step 310, the particle group 36 (see FIG. 14) located on the display substrate 18 side passes through the hole 44 of the porous member 48 and reaches the back substrate 20 side (FIG. 16). reference).

  In the next step 312, a signal indicating stoppage of voltage application to the front electrode 24 and the back electrode 30 is output to the voltage application unit 14. When the signal is received, the voltage application unit 14 stops the voltage application to the front electrode 24 and the back electrode 30.

  In the next step 314, after outputting a signal indicating that light irradiation is stopped to the light stimulus applying unit 76, this routine is ended.

  When the light irradiation by the light stimulus imparting unit 76 is stopped by the process of step 314, the first member 46 released by the process of step 304 and step 306 is in the blocking state. For this reason, the movement of the particle group 36 through the hole 44 of the porous member 48 is prevented by the process of step 314, and the particle group 36 moved to the display substrate 18 side or the back substrate 20 side by the process of step 308 is The movement from the back substrate 20 side to the display substrate 18 side is prevented, and the state is held on the back substrate 20 side.

  On the other hand, in the same manner when the processing of Step 300 to Step 314 is performed so that the particle group 36 is located on the display substrate 18 side from the state located on the rear substrate 20 side, The particle group 36 that has moved from the substrate 20 side to the display substrate 18 side is held on the moved display substrate 18 side.

  Specifically, after the particle group 36 located on the back substrate 20 side reaches the display substrate 18 side through the hole 44 of the porous member 48, the first member 46 changes to the blocking state. To do. Accordingly, the particle group 36 that has moved to the display substrate 18 side is prevented from moving to the back substrate 20 side, and is held on the display substrate 18 side.

  For this reason, in the display device 70 of the present embodiment, it is possible to suppress a decrease in image quality retention on the display medium 12.

  Hereinafter, the above embodiment will be described more specifically with reference to examples. However, these examples do not limit the present invention.

(Example 1)
A reflective member 38 having a structure in which a polymer gel that swells or contracts by thermal stimulation as the first member 46 is coated on a mesh (network member) made of polyester as the porous member 48 is produced.

  As the porous member 48, a polyester mesh cloth having a fiber (polyester fiber) diameter of 40 μm, an opening of 40 μm, an opening ratio of 25%, and a thickness of 60 μm was used. A reflective member 38 was produced by coating the surface of the polyester mesh with white N-isopropylacrylamide gel as the first member 46 (see the reflective member 38 shown in FIG. 4).

  Specifically, a solution in which 10 parts by weight of a titanium oxide dispersion (dispersion concentration: 10 wt%) having an average particle diameter of 0.1 μm as a white pigment was mixed with 1 part by weight of pre-synthesized poly (N-isopropylacrylamide). The polyester mesh cloth (10 cm × 10 cm square) was immersed in this solution and then dried to form a white poly (N-isopropylacrylamide) layer on the fiber surface of the polyester mesh cloth. Furthermore, the mesh cloth was irradiated with an electron beam to crosslink poly (N-isopropylacrylamide) to be gelled. Thus, the first member 46 made of N-isopropylacrylamide gel was provided on the surface of the polyester mesh cloth as the porous member 48.

The stimulus responsiveness of the reflecting member 38 was evaluated as follows.
When the reflecting member 38 produced above was immersed in pure water (20 ° C.) and the reflecting member 38 in this state was observed with a microscope, the mesh between the meshes of the polyester mesh cloth (mesh opening 40 μm), that is, the holes were high. It was covered with a white layer made of a molecular gel, and it was confirmed that the polymer gel absorbed pure water and swelled to block the pores of the polyester mesh cloth (blocked state).

  On the other hand, when the reflecting member 38 was heated while being immersed in pure water and kept at 40 ° C. for 10 seconds, the mesh of the polyester mesh cloth (mesh size 40 μm) was observed. Between, that is, the pores were not covered with the polymer gel, and pores having an average diameter of about 20 μm were generated (released state). This is presumably because the polymer gel contracted by releasing pure water when heat was applied.

  The size of the holes was obtained by calculating the average diameter per hole from the result of measuring the diameter of at least 10 holes with a microscope.

  Further, when the reflecting member 38 was cooled to 20 ° C. while being immersed in pure water again and held for 10 seconds, the reflecting member 38 was observed with a microscope. 40 μm), that is, the pores were again covered with the polymer gel and became blocked.

  Thus, it has been found that the hole of the reflecting member 38 reversibly changes to a state covered or released by the polymer gel due to a temperature change.

  A display medium 1 was produced using the reflective member 38 produced in Example 1.

-Particle group and dispersion medium-
As the particle group and the dispersion medium, a carbon black water dispersion liquid (large size) in which black carbon black (corresponding to the particle group 36) having an average primary particle diameter of 0.2 μm is dispersed in pure water (corresponding to the dispersion medium 42). Nippon Ink: MC Black, carbon black concentration 2% by weight) was used. From the electrophoretic evaluation of this carbon black dispersion, the particles were charged to the negative electrode and had the property of migrating to the anode side.

-Production of display media-
A surface layer is formed by applying a polycarbonate resin to a thickness of about 0.5 μm on a 50 mm × 50 mm tin oxide electrode substrate, and then a 100 μm resin spacer (gap member) is formed on the surface layer. Corresponding to the edge of the electrode substrate. Thus, a structure in which a gap member (100 μm) was provided on the back substrate was produced.
The resin spacer was formed by adhering a thermoplastic film on the surface layer of the electrode substrate.

  First, the produced reflection member 38 (polyester mesh cloth whose surface is coated with N-isopropylacrylamide gel) is positioned around an intermediate position between the display substrate and the back substrate of the produced display medium. The carbon black aqueous dispersion is placed in each cell in which the gap member is provided on the back substrate and the reflection member 38 is provided, and is fixed by using a film spacer between the gap members. Filled.

  Further, an electrode substrate with tin oxide having a size of 50 mm × 50 mm similar to the above was used as a display substrate, and the electrode surface was disposed so as to face the gap member, and then the outer peripheral portion was sealed with a thermal adhesive. Thereby, the display medium 1 was produced.

  When the produced display medium 1 was observed with an atomic force microscope, the reflecting member 38 was disposed in a substantially central portion between the display substrate and the back substrate in the plate surface direction of the display substrate.

-Evaluation-
After 1 minute had passed since the obtained display medium 1 was heated to 40 ° C. with a sheet-type heater, the state of the holes on the reflecting member 38 was confirmed. As a result, holes with an average hole diameter of 20 μm were confirmed. Furthermore, when a DC voltage of 3 V was applied between the display substrate side electrode and the back substrate side electrode with the display substrate side electrode as a positive electrode for 10 seconds, the display medium 1 was viewed from the display substrate side. The color at the time, that is, the display color, changed from white to black. When the density of the display medium 1 at this time was measured with a reflection densitometer (X-rite 404) manufactured by X-rite, the reflectance was 5%. The concentration of the display medium 1 was measured from the display substrate side.

  In this state, the temperature was quickly cooled to 30 ° C. or less (at a rate of 5 ° C. per minute), the voltage application was stopped, and the temperature application was stopped at this temperature of 30 ° C. for 24 hours. When the density of the display medium 1 was measured again from the display substrate side in the same manner as described above, the reflectance was 5%, and high image retention was confirmed.

  Next, after 1 minute had passed since the display medium 1 was again heated to 40 ° C., the state of the holes on the reflecting member 38 was confirmed, and holes having an average hole diameter of 20 μm were confirmed. In this state, when a DC voltage of 3 V was applied for 10 seconds between the electrode on the display substrate side and the electrode on the back substrate side with the electrode on the display substrate side as the negative electrode, the carbon black particles were polyester mesh cloth. The state of moving to the back substrate side through the screen was confirmed, and the color of the display medium 1 changed from black to white. In this state, the temperature of the display medium 1 was further cooled to 30 ° C. or lower and held at the cooled temperature for 1 minute. When the density of the display medium 1 at this time was measured in the same manner as described above, the reflectance was 60%. The concentration of the display medium 1 was measured from the display substrate side. Thus, it was found that the display medium 1 has a high contrast ratio of 12 between the state of displaying black and the state of displaying white.

  In addition, when the white color is displayed and held at a temperature of 30 ° C. or lower for 24 hours, the density of the display medium 1 is measured again from the display substrate side in the same manner as described above, and the reflectance is 60%. High image retention was confirmed.

  Further, in this display medium 1, after the black display and the white display were repeatedly executed 100 times, the image quality retention at the time of the black display and the white display was evaluated again. The density before and after being left for 24 hours and the density before and after being left for 24 hours after white display were the same value, and high image quality retention was confirmed.

  Such a high contrast and image quality retention of the display medium 1 manufactured in Example 1 is due to the change in temperature of the display medium 1 due to a change in temperature, in a shielded state in which pores are covered with a polymer gel, or in particles that undergo electrophoresis. It is considered that this is achieved by providing a reflecting member 38 that changes to a released state released to a size that allows passage.

(Example 2)
In the first embodiment, as the reflecting member 38, a case where the reflecting member 38 having a structure in which a polyester mesh as the porous member 48 is coated with a polymer gel that swells or contracts by thermal stimulation is used as the first member 46 is described. However, in this second embodiment, in place of the reflecting member 38 used in the first embodiment, the reflecting member 38 adjusted in the second embodiment (see the reflecting member 38 shown in FIG. 3) is used. A display medium was prepared in the same manner as in Example 1 and the image quality retention was evaluated.

  Specifically, in Example 2, a sponge-like polymer film containing titanium oxide is used as the porous member 48, and the first member 46 is spherical and thermally stimulated in the pores of the polymer film. A reflecting member 38 on which a polymer gel that swells or contracts is fixed was used.

  As the porous member 48, a polyurethane sponge-like resin film (thickness 50 μm) containing titanium oxide having an average particle diameter of 0.2 μm at a concentration of 30% by weight was used. This sponge-like film was prepared by adding salt crystals to polyurethane containing titanium oxide and immersing this in water to elute the salt. A hole penetrating in the thickness direction having an average pore diameter of 8 μm was formed inside the membrane of the produced porous member 48. Further, the visible light reflectance of the porous member 48 was 65%. The visible light reflectance of the porous member 48 is a measurement result obtained by measuring the reflectance of the porous member 48 in pure water using a reflection densitometer (X-rite 404) manufactured by X-rite. .

A reflecting member 38 was prepared by fixing a spherical polymer gel that swells or contracts by thermal stimulation as the first member 46 in the pores of the porous member 48.
Specifically, the porous member 48, which was a sponge-like polymer film, was rinsed with a 0.1 wt% ethanol solution of γ-aminopropyltrimethoxysilane, and then heat-dried to aminate the surface.

Next, separately, spherical polymer gel particles obtained by copolymerizing acrylic acid to 0.5% by weight of N-isopropylacrylamide by suspension polymerization (particle size when swollen in pure water at 20 ° C. is 10 μm, 40 The dispersion was prepared by dispersing the polymer gel particles in pure water. Then, the porous member 48, which is the sponge-like polymer film produced above, is dispersed in a state where the dispersed polymer gel is contracted by heating the dispersion to 40 ° C. and allowing it to stand for 1 minute. The gel particles were fixed in the pores by dipping in the liquid.
When the porous member 48 was observed with a microscope, it was confirmed that the polymer gel was fixed in each hole of the porous member 48.

The stimulus responsiveness of the produced reflecting member 38 was evaluated as follows.
When the reflecting member 38 produced in Example 2 was immersed in pure water (20 ° C.) and the reflecting member 38 in the permeated state was observed with a microscope, the reflecting member 38 was fixed in the pores of the polymer film. The polymer gel that had swollen closed the pores and was in a blocking state.

  On the other hand, when the reflecting member 38 in a state where the reflecting member 38 was heated and kept at 40 ° C. for 10 seconds while being permeated in pure water was observed with a microscope, the pores of the polymer film were The gaps of about 5 μm on average were generated (released state). This is presumably because the polymer gel contracted by releasing pure water when heat was applied.

  The size of the holes was obtained by calculating the average diameter per hole from the result of measuring the diameter of at least 10 holes with a microscope.

  Furthermore, when the reflecting member 38 was cooled to 20 ° C. with the reflecting member 38 infiltrated into pure water and held for 10 seconds, the hole in the polymer film was found again. It was blocked by the polymer gel and became blocked.

  As described above, it was found that the hole of the reflecting member 38 reversibly changes to a state blocked (blocked state) or released (released state) by the polymer gel due to the temperature change.

  Using the reflective member 38 produced in Example 2, the display medium 2 was produced in the same manner as the display medium 1 produced in Example 1 except that the reflective member was different, and the image storage stability was evaluated.

-Evaluation-
After 1 minute had passed since the obtained display medium 2 was heated to 40 ° C. with a sheet heater, the state of the holes on the reflecting member 38 was confirmed. As a result, holes (gap) having an average hole diameter of 5 μm were confirmed. Further, when a 3 V DC voltage was applied for 10 seconds between the display substrate side electrode and the back substrate side electrode with the display substrate side electrode as a positive electrode, the display medium 2 was viewed from the display substrate side. The color at the time, that is, the display color, changed from white to black. The density of the display medium 2 at this time was measured with a reflection densitometer (X-rite 404) manufactured by X-rite, and the reflectance was 5%. The concentration of the display medium 2 was measured from the display substrate side.

  In this state, the temperature was quickly cooled to 30 ° C. or less (at a rate of 5 ° C. per minute), the voltage application was stopped, and the temperature application was stopped at this temperature of 30 ° C. for 24 hours. When the density of the display medium 2 was measured again from the display substrate side in the same manner as described above, the reflectance was 5%, and high image retention was confirmed.

  Next, after 1 minute has passed since the display medium 2 was heated again to 40 ° C., the state of the holes on the reflecting member 38 was confirmed. As a result, holes with an average hole diameter of 5 μm were confirmed. In this state, when a DC voltage of 3 V was applied for 10 seconds between the electrode on the display substrate side and the electrode on the back substrate side with the electrode on the display substrate side as the negative electrode, the carbon black particles were on the back substrate side. The color of the display medium 2 changed from black to white. In this state, the temperature of the display medium 2 was further cooled to 30 ° C. or lower and held at the cooled temperature for 1 minute. When the density of the display medium 2 at this time was measured in the same manner as described above, the reflectance was 65%. In this way, it was found that the display medium 2 showed a high contrast ratio of 13 when displaying black and when displaying white.

  In addition, when the white color is displayed and held at a temperature of 30 ° C. or lower for 24 hours, the density of the display medium 2 is measured again from the display substrate side in the same manner as described above, and the reflectance is 65%. High image retention was confirmed.

  Further, in this display medium 2, after the black display and the white display were repeatedly executed 100 times, the image quality retention during the black display and the white display was evaluated again. The density before and after being left for 24 hours and the density before and after being left for 24 hours after white display were the same value, and high image quality retention was confirmed.

  Such a high contrast and image quality retention of the display medium 2 manufactured in Example 2 is caused by the change in the temperature of the display medium 2 by the particulate polymer gel (first member 46). It is thought that this is achieved by providing a reflecting member 38 that changes to a shielded state in which the hole is blocked, or a released state in which the hole is released to a size that allows passage of the electrophoretic particles. It is done.

(Example 3)
In the first embodiment, as the reflecting member 38, a case where the reflecting member 38 having a structure in which a polyester mesh as the porous member 48 is coated with a polymer gel that swells or contracts by thermal stimulation is used as the first member 46 is described. However, in the third embodiment, instead of the reflecting member 38 used in the first embodiment, the reflecting member 38 adjusted in the third embodiment (see the reflecting member 38 shown in FIG. 5) is used. A display medium was produced in the same manner as in Example 1 except that the stimulus was directly applied to the reflecting member 38, and the image quality retention was evaluated.

  Specifically, in Example 3, a mesh-like electrode is used as the porous member 48, and the surface of the mesh-like electrode is covered with a material (fluorine resin) whose surface free energy is changed by applying electrical stimulation. Thus, the reflecting member 38 having the configuration in which the first member 46 is provided was used.

  As the porous member 48, a stainless mesh electrode (mesh wire diameter: 100 μm, aperture: 30 μm, aperture ratio: 15%, thickness: 150 μm) was prepared. The surface of the mesh electrode as the porous member 48 is coated with a fluororesin (polytetrafluoroethylene) in which 0.2 μm of titanium oxide is dispersed at 20% by weight and then dried, whereby the surface of the mesh electrode is approximately 10 μm white. The fluororesin layer (first member 46) was formed. Thereby, the reflecting member 38 was produced.

  A display medium 3 was produced using the reflective member 38 produced in Example 3.

-Particle group and dispersion medium-
As the particle group and the dispersion medium, polymer particles containing a magenta pigment (average primary particle size is 200 nm) are used as the particle group 36, and a dispersion liquid (concentration of polymer particles) in which the particle group 36 is dispersed in Isopar G. Was 2% by weight). The polymer particles have a surface charged with a charging material for surface charging, are positively charged, and are hydrophilic. Moreover, when an electric field is applied in a liquid, it shows a characteristic of migrating in the negative electrode direction.

-Production of display media-
A surface layer is formed by applying a polycarbonate resin so as to have a thickness of about 0.5 μm on a 50 mm × 50 mm tin oxide electrode substrate, and then a 100 μm resin spacer is formed on the surface layer. Then, the reflective member 38 produced in Example 3 was disposed, and a resin spacer of 100 μm was disposed so as to sandwich the reflective member 38 between the resin spacer previously disposed. . As a result, a 200 μm gap member (two layers of 100 μm resin spacers) was provided on the back substrate, and a reflecting member 38 was disposed at an intermediate position in the height direction of the gap member.

Further, the dispersion liquid in which the polymer particles were dispersed was filled in each cell in which the gap member was provided on the back substrate and the reflection member 38 was provided.
Further, an electrode substrate with tin oxide having a size of 50 mm × 50 mm was used as a display substrate, and the electrode surface was disposed so as to face the gap member, and then the outer peripheral portion was sealed with a thermal adhesive. Thereby, the display medium 3 was produced.

-Evaluation-
A 30 V DC voltage having different polarity was alternately applied between the display substrate side electrode and the back substrate side electrode of the obtained display medium 3, but no color change occurred in the display medium 3. This is because the polymer particles (particle group 36) exhibiting high hydrophilicity are porous because the fluororesin coating the surface of the stainless mesh electrode (porous member 48) constituting the reflecting member 38 has high hydrophobicity. This is considered because it cannot pass through the hole of the member 48 (the state shown in FIG. 5A).

  Next, a voltage of 30 V was directly applied to the stainless mesh electrode, and simultaneously, a DC voltage of 30 V having a different polarity was alternately applied between the display substrate side electrode and the back substrate side electrode. Magenta and white were displayed alternately. This is because when the voltage is applied to the stainless steel mesh electrode, the surface of the fluororesin as the first member 46 covering the surface of the stainless steel mesh electrode changes to a high free energy state (ie, hydrophilic). This is considered to be because the polymer particles can move between the substrates.

Further, by applying a voltage of 30 V directly to the stainless mesh electrode, and simultaneously applying a DC voltage of 30 V having a different polarity between the electrode on the display substrate side and the electrode on the back substrate side, the magenta color and After displaying each white color, the concentration of the display medium 3 immediately after the voltage application to the stainless mesh electrode and the electrodes on both the display substrate side and the back substrate side was measured in the same manner as in Example 1. The density at the time of magenta color display was 5% in peak reflectance, and the density at the time of white display was 55% reflectance.
Further, after the magenta color and the white color were displayed, the voltage application was stopped and left for 24 hours, and then the density of the display medium 3 was measured in the same manner. After the magenta color display was stopped, the voltage application was stopped. The density after the lapse of time was 5% in reflectance, and the density after 24 hours after the voltage application was stopped after white display was 55% in reflectance. Thus, high image retention was confirmed.

  This is because the fluororesin provided as the first member 46 on the reflecting member 38 of the display medium 3 changes to hydrophobic by stopping the application of voltage, thereby preventing the movement of hydrophilic polymer particles between the substrates. It is thought that it is to do.

  As described above, high image quality retention was also confirmed in the display medium 3.

Example 4
In the first embodiment, as the reflecting member 38, a case where the reflecting member 38 having a structure in which a polyester mesh as the porous member 48 is coated with a polymer gel that swells or contracts by thermal stimulation is used as the first member 46 is described. However, in the fourth embodiment, instead of the reflecting member 38 used in the first embodiment, a polyester mesh as the porous member 48 is replaced with a tria that is ionized and charged as a first member 46 by cleaving by light stimulation. The case where the reflecting member 38 having a structure in which a polymer containing a reel methane derivative is surface-coated is used will be described.

As the porous member 48, as in Example 1, a polyester mesh cloth having a fiber (polyester fiber) diameter of 40 μm, an opening of 40 μm, an opening ratio of 25%, and a thickness of 60 μm was prepared. A titanium oxide-containing layer having a thickness of 10 μm is formed on the polyester mesh cloth by applying polystyrene containing titanium oxide to the polyester mesh cloth by a solution coating method (after immersing the mesh in a polymer solution and then lifting and drying). A white mesh body was produced as the porous member 48.

  Furthermore, a polymer obtained by copolymerizing a polymerizable trialmethane compound having a vinyl group represented by the following general formula (VIII) with methyl methacrylate at a composition ratio of 5% by weight was synthesized by a solution coating method as described above. The reflective member 38 was produced by providing the first member 46 by applying to the surface of the white mesh body (porous member 48) produced above.

Formula (VIII)

  Before and after the surface potential of the reflecting member 38 (the surface of the white mesh body coated with a polymer containing a trialmethane derivative) was irradiated with ultraviolet rays having a wavelength of 340 nm to 380 nm, Kawaguchi was prepared. When measured using a product name: S2002A manufactured by Denki Seisakusho Co., Ltd., it was found that it was uncharged before being irradiated with ultraviolet rays, but positively charged when irradiated with ultraviolet rays (irradiating for 10 seconds).

In addition, after irradiating visible light of 450 nm to 700 nm to the reflective member 38 that was positively charged by ultraviolet irradiation, the surface potential was measured again in the same manner as described above.
It has also been found that the repetition of the uncharged state and the positively charged state can be repeated by using the ultraviolet light or the visible light as the irradiation light.

  This is presumably because the triarmethane compound used as the first member 46 cleaves ions by irradiation with ultraviolet rays to generate positive ions.

  Using the reflective member 38 produced in Example 1, the reflective member 38 produced in Example 3 was used instead of the reflective member 38 of the display medium 1 produced in Example 1, and produced in Example 1. The display medium 4 was produced in the same manner as in Example 1 except that the following particle group and dispersion medium were used instead of the particle group and dispersion medium used in the display medium 1, and the image storage stability was evaluated. .

-Particle group and dispersion medium-
As the particle group and the dispersion medium, polymer particles containing a magenta pigment (average primary particle size is 200 nm) are used as the particle group 36, and a dispersion liquid (concentration of polymer particles) in which the particle group 36 is dispersed in Isopar G. Was 2% by weight). The polymer particles have a surface charged with a charging material for surface charging, are positively charged, and are hydrophilic. Moreover, when an electric field is applied in a liquid, it shows a characteristic of migrating in the negative electrode direction.

-Evaluation-
A 30 V DC voltage of different polarity is alternately applied between the display substrate side electrode and the back substrate side electrode in a state in which the obtained display medium 4 is not irradiated with ultraviolet rays and is irradiated with visible light. As a result, magenta color and white color could be alternately displayed on the display medium 4.

  Further, the reflectance at the time of white display was measured from the display substrate side by X-rite404 manufactured by X-rite, and it was 50%. Further, the density when displaying magenta color was 5% in terms of peak reflectance.

  Further, each of the white display and the magenta display was maintained in a state where a voltage was applied to the electrodes on the display substrate side and the electrodes on the rear substrate side, but when the voltage application was stopped, the color density was reached in about 5 minutes. The change was seen.

  Next, in the state where magenta color is displayed on the display medium 4 by applying a voltage to the electrode on the display substrate side and the electrode on the rear substrate side of the display medium 4, ultraviolet rays are applied for 10 seconds from the rear substrate side of the display medium 4. When irradiated, the density immediately after stopping the voltage application after UV irradiation and the density after standing for 24 hours are 5% in peak reflectance (measured by X-rite 404), and the color density does not change at all. I understood it.

  This is because, by irradiating ultraviolet rays, the surface of the reflecting member 38 is charged to a positive potential due to ion cleavage of the triarmethane compound, so that the positively charged polymer particles (particle group 36) are electrostatically repelled. This is considered to suppress the passage of the particle group 36 through the pores of the porous member 48 of the reflecting member 38.

  On the contrary, when the display medium 4 is irradiated with ultraviolet rays for 10 seconds with the particle group held on the back substrate side from the reflecting member 38, the concentration immediately after the voltage application is stopped after the ultraviolet irradiation, The density after standing for 24 hours was 50% in reflectance (measured by X-rite 404), and it was found that the white density did not change at all.

Furthermore, after UV light irradiation is stopped and visible light is irradiated onto the display medium 4 for 10 seconds, a 30 V DC voltage having a different polarity is alternately applied between the display substrate side electrode and the back substrate side electrode again. When applied, magenta color and white color could be displayed alternately on the display medium 4.
As described above, it was confirmed that the display medium 4 manufactured in Example 4 can obtain high image retention and can be controlled by irradiating with ultraviolet rays.

(Comparative Example 1)
A display medium was prepared in the same manner as in Example 1 except that the polymer gel particles were not fixed in the pores of the white sponge-like porous body, and evaluated in the same manner as in Example 2.

-Evaluation-
After applying a 3V DC voltage between the display substrate side electrode and the back substrate side electrode of the obtained display medium for 10 seconds, the application of the 3V DC voltage was stopped, and then 25 ° C. and 60%. When left in an RH environment, the color density started to change in about 5 minutes, and after 24 hours, the density of the display medium was measured again in the same manner as described above. (In the initial white state, the reflectivity was 65%, but it dropped to 35%).
Thus, the display medium produced in Comparative Example 1 has a density change.

It is a schematic block diagram which shows the display medium of 1st Embodiment. It is a diagram showing the voltage range required until the display density does not change and the display density is saturated even if the voltage and voltage application time are further increased from the start of movement and the voltage necessary to start the movement of the particle group. It is a diagram which shows the relationship between the electric potential difference per unit distance and the amount of particle movement. It is a schematic diagram which shows an example of the reflective member in the display medium of 1st Embodiment, (A) shows a blocking state, (B) is a schematic diagram which shows a cancellation | release state. It is a schematic diagram which shows an example of the reflective member in the display medium of 1st Embodiment, (A) shows a blocking state, (B) is a schematic diagram which shows a cancellation | release state. It is a schematic diagram which shows an example of the reflective member in the display medium of 1st Embodiment, (A) shows a blocking state, (B) is a schematic diagram which shows a cancellation | release state. It is a schematic block diagram which shows the display medium of 1st Embodiment. It is a schematic block diagram which shows the display apparatus of 2nd Embodiment. It is a flowchart which shows the process performed by CPU of the control part of the display apparatus of 2nd Embodiment. It is a schematic block diagram which shows the display apparatus of 2nd Embodiment. It is a schematic block diagram which shows the form different from FIG.7 and FIG.9 of the display apparatus of 2nd Embodiment. It is a schematic block diagram which shows the display apparatus of 3rd Embodiment. It is a flowchart which shows the process performed by CPU of the control part of the display apparatus of 3rd Embodiment. It is a schematic block diagram which shows the display apparatus of 3rd Embodiment. It is a schematic block diagram which shows the display apparatus of 4th Embodiment. It is a flowchart which shows the process performed by CPU of the control part of the display apparatus of 4th Embodiment. It is a schematic block diagram which shows the display apparatus of 4th Embodiment.

Explanation of symbols

10, 50, 60 Display device 12 Display medium 14 Voltage application unit 16, 54, 68 Control unit 18 Display substrate 20 Back substrate 24 Front electrode 30 Back electrode 38 Reflective member 42 Dispersion medium 48, 48A, 48B, 48C Porous member 46 , 46A, 46B, 46C First member 66 Thermal stimulus applying member 76 Light stimulus applying portion

Claims (10)

A pair of substrates at least one having translucency and disposed with a gap;
A group of particles encapsulated between the pair of substrates and moving according to an electric field formed between the substrates;
A dispersion medium enclosed between the pair of substrates and for dispersing the particle group;
It is provided between the pair of substrates, has a hole through which the particle group passes, and has an optical reflection characteristic different from that of the particle group, and allows the particle group to pass through the hole by applying a stimulus. A reflecting member that changes to a blocking state to block or a released state that releases the blocking state;
A display medium comprising: The reflective member is
A porous member provided between the pair of substrates, having a hole through which the particle group passes and having optical reflection characteristics different from the particle group;
A first member that is provided in the porous member and changes to a blocking state in which the passage of the particles to the pores of the porous member is blocked or a released state in which the blocking state is released by applying a stimulus. When,
The display medium according to claim 1, further comprising:   The display medium according to claim 2, wherein the first member is provided in at least the hole of the porous member, and swells or contracts when the stimulus is applied.   The display medium according to claim 3, wherein the first member is a polymer gel that changes in volume by absorbing or releasing the dispersion medium upon application of the stimulus. The particles are pre-charged,
The display medium according to claim 2, wherein the first member is provided on a surface of the porous member, and charging characteristics are changed by applying the stimulus. The particles are pre-charged,
The display medium according to claim 2, wherein the first member is provided on a surface of the porous member and changes to hydrophobic or hydrophilic by the application of the stimulus.   The display medium according to claim 1, wherein the stimulus is electricity.   The display medium according to claim 1, wherein the stimulus is heat or light. At least one of the pair of substrates having translucency and disposed with a gap, a particle group enclosed between the pair of substrates and moving according to an electric field formed between the substrates, and between the pair of substrates And a dispersion medium for dispersing the particle group, provided between the pair of substrates, having a hole through which the particle group passes and having an optical reflection characteristic different from that of the particle group, A reflecting member that changes to a blocking state in which the particle group is prevented from passing through the hole or a released state in which the blocking state is released,
A stimulus applying means for applying a stimulus to the reflecting member of the display medium;
Voltage applying means for forming an electric field between the pair of substrates by applying a voltage to the display medium;
A display device comprising: At least one of the pair of substrates having translucency and disposed with a gap, a particle group enclosed between the pair of substrates and moving according to an electric field formed between the substrates, and between the pair of substrates And a dispersion medium for dispersing the particle group, provided between the pair of substrates, having a hole through which the particle group passes and having an optical reflection characteristic different from that of the particle group, And a reflecting member that changes to a blocking state that prevents the passage of the particle group into the hole or a released state that releases the blocking state, and the reflecting member of the display medium. A computer that performs display driving of a display device that includes stimulus applying means for applying a stimulus to the display medium and voltage applying means for forming an electric field between the pair of substrates by applying a voltage to the display medium. An image display program to be executed, a first step of controlling the stimulus applying means to apply a stimulus to the reflecting member in the release state,
A second step of controlling the voltage application means to form an electric field between a pair of substrates of the display medium;
A third step of controlling the stimulus applying means to apply a stimulus for bringing the reflecting member into the blocking state;
A display program that causes a computer to execute.