JP2011253008A - Writing device, display device, display medium, and display program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent color mixing in a display medium containing at least two kinds of particles in different colors.SOLUTION: Two kinds of electrophoretic particles 24 are sealed between substrates, the particles comprising positively charged magenta migration particles 24M colored in magenta and negatively charged cyan migration particles 24C colored in cyan, and white particles 26 colored in white are added to the electrophoretic particles 24 and sealed between the substrates. The electrophoretic particles 24 sealed between the substrates exhibit such properties that at a voltage V2, the migration particles in different colors separate from each other and move in opposite directions to each other and that at a voltage V1 (V2>V1) or lower, the particles form aggregates to move. A voltage to be applied between the substrates is controlled to form aggregates on the substrate.

Description

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

  Various techniques for performing black and white display and color display using an electrophoretic display element in which electrophoretic particles are sealed between a pair of electrodes having at least one light-transmitting property have been proposed (for example, Patent Document 1).

  In the technique described in Patent Document 1, a first substrate serving as a display unit, a second substrate disposed to face the first substrate, and a substrate between each substrate are provided. By applying an electric field to each electrophoretic particle, a pixel space formed by enclosing an electrophoretic dispersion liquid containing a plurality of types of electrophoretic particles different from each other and a liquid phase dispersion medium in which each electrophoretic particle is dispersed, Using a difference in electrophoretic mobility between each electrophoretic particle, a pair of separation electrodes for separating each electrophoretic particle by type, and a specific electrophoretic particle among the separated electrophoretic particles There has been proposed a display device including a pair of transfer electrodes that move the electrophoretic particles to the display unit side of the pixel space by sorting and applying an electric field.

JP 2008-116512 A

  An object of the present invention is to prevent color mixing in a display medium including at least two kinds of particles having different colors.

  The writing device according to claim 1 is sealed between a pair of substrates, at least one of which has translucency, has different optical characteristics, and at least one kind of particles is opposite in polarity to the other kinds of particles. At least two or more kinds of particles charged in polarity, a first electrode having translucency provided on one substrate side having translucency of the substrate, and the other electrode facing the first electrode. And at least two types of the two or more types of particles that are oppositely charged on one of the pair of substrates with respect to a display medium including a second electrode provided on the substrate side. An image is written on the display medium by applying a voltage between the first electrode and the second electrode so that the particles form aggregates.

  According to a second aspect of the present invention, in the first aspect of the invention, the two types of particles form aggregates at a predetermined first voltage or less and move as aggregates, and the first particles The agglomerates are separated by a second voltage higher than the voltage and move in opposite directions.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the two types of particles have different threshold voltages for moving between the substrates, and the threshold voltage of the particle having the higher threshold voltage. In the following, the particles having the lower threshold voltage move to form aggregates.

  The invention described in claim 4 is characterized in that, in the invention described in any one of claims 1 to 3, the at least two or more kinds of particles have different moving speeds.

  The display device according to claim 5 is sealed between a pair of substrates, at least one of which has translucency, has different optical characteristics, and at least one kind of particles has a polarity opposite to that of other kinds of particles. Two or more kinds of charged particles, a translucent first electrode provided on the translucent one substrate side of the substrate, and the other substrate facing the first electrode The second electrode provided on the side and one of the pair of substrates so that at least two kinds of the two or more kinds of particles charged with opposite polarities form an aggregate. Control means for controlling a voltage applied between the first electrode and the second electrode.

  The display medium according to claim 6, wherein at least one of the pair of substrates having a light transmitting property is sealed between the pair of substrates, the optical characteristics are different, and each is charged with a reverse polarity, When a voltage equal to or lower than a predetermined first voltage is applied between the pair of substrates, an aggregate is formed on one of the pair of substrates and moves as the aggregate, and the first When a second voltage higher than a voltage of 1 is applied between the pair of substrates, the aggregate includes two types of particles that separate and move in opposite directions.

  The display program according to claim 7, wherein at least one of the particles is sealed between a pair of translucent substrates and has different optical characteristics, and at least one kind of particles has a polarity opposite to that of other kinds of particles. Two or more kinds of charged particles, a translucent first electrode provided on the translucent one substrate side of the substrate, and the other substrate facing the first electrode A display device comprising: a second electrode provided on a side; and an application unit configured to apply a voltage between the first electrode and the second electrode, on one of the pair of substrates, The computer is caused to execute a process for controlling the applying means so that at least two kinds of particles having opposite polarities among the two or more kinds of particles form aggregates.

  According to the invention described in claims 1 to 7, in a display medium including at least two or more kinds of particles having different colors, color mixing is prevented as compared with a case where the two kinds of particles do not form an aggregate on the substrate. There is an effect that can be.

It is a figure which shows the outline of the display apparatus concerning embodiment of this invention. It is a figure for demonstrating the movement of the particle | grains of the display apparatus with which three types of particle | grains from which a moving speed differs were enclosed. It is a figure for demonstrating the movement of the particle | grains of the display apparatus concerning embodiment of this invention, (A) shows the example which displayed the cyan color, (B) shows the example which displayed the magenta color, ( C) shows an example displaying white, and (D) shows an example displaying blue. (A) is a figure which shows the example which aggregated the electrophoretic particle between board | substrates, (B) is a figure which shows the example which electrophoretic particle was aggregated on the board | substrate. It is a flowchart which shows an example of the flow of a color display process of the display apparatus concerning embodiment of this invention.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically showing a display device according to an embodiment of the present invention.

  The display device 10 according to the embodiment of the present invention includes an electrophoretic display element 12 that displays an image by movement of at least two or more types of electrophoretic particles 24, and a voltage for causing the electrophoretic display element 12 to display an image. A voltage application device 14 to be applied and a drive control device 18 that controls the drive of the voltage application device 14 in response to an image display instruction from an external image signal output device 16 such as a personal computer are configured.

  The electrophoretic display element 12 includes a translucent display substrate 20 serving as an image display surface, and a back substrate 22 disposed opposite to the display substrate 20 with a predetermined interval. . Note that the light-transmitting property indicates that the visible light transmittance is 70% or more, preferably 90% or more.

  Between the display substrate 20 and the back substrate 22, a translucent dispersion liquid 28 is enclosed, and at least two or more types of electrophoretic particles 24 colored in the dispersion liquid 28 are enclosed. At least two or more types of electrophoretic particles 24 are charged with opposite polarity and have different optical characteristics (colored in different colors).

  In the present embodiment, two types of electrophoretic particles 24, a magenta electrophoretic particle 24 </ b> M colored in magenta and a cyan electrophoretic particle 24 </ b> C colored in cyan, are enclosed between the substrates, and the electrophoretic particles 24 are included in the electrophoretic particles 24. In addition, an example in which white particles 26 colored in white are further sealed between the substrates is shown. Each electrophoretic particle 24 moves according to the electric field strength formed between the substrates.

  In the present embodiment, the magenta electrophoretic particles 24M are positively charged, and the cyan electrophoretic particles 24C are negatively charged. The magenta migrating particles 24M and the cyan migrating particles 24C have different threshold voltages, and when the magenta migrating particles 24M and the cyan migrating particles 24C are aggregated, the aggregates are negatively charged. The moving speeds of the magenta migrating particles 24M and the cyan migrating particles 24C are different from each other, but may be the same.

  The display substrate 20 is provided with a surface electrode 36 on a support substrate 34, and the back substrate 22 is provided with a back electrode 40 on a support substrate 38 facing the surface electrode 36.

  As the support substrates 34 and 38, glass or plastic can be applied. Examples of the plastic include polycarbonate resin, acrylic resin, polyimide resin, polyester resin, epoxy resin, and polyether sulfone resin.

  For the surface electrode 36 and the back electrode 40, oxides such as indium, tin, cadmium and antimony, composite oxides such as ITO, metals such as gold, silver, copper and nickel, organic materials such as polypyrrole and polythiophene are used. can do. These can be formed by a single layer film, a composite film, or a composite film and a vapor deposition method, a sputtering method, a coating method, or the like.

  Although FIG. 1 shows an example in which the surface electrode 36 is laminated on the support substrate 34 and the back electrode 40 is laminated on the support substrate 38, the surface electrode 36 and the back electrode 40 are embedded in each support substrate. May be. Further, when the front electrode 36 and the back electrode 40 are embedded in each support substrate, the materials of the support substrates 34 and 38 may affect the electrical characteristics and fluidity of each electrophoretic particle 24. It is necessary to select according to the composition of the migrating particles 24.

  In addition, each of the front electrode 36 and the back electrode 40 may be separated from the display substrate 20 and the back substrate 22 and disposed outside the electrophoretic display element 12. In the present embodiment, a case is described in which electrodes (surface electrode 36 and back electrode 40) are provided on both the display substrate 20 and the back substrate 22, but only one of them may be provided.

The dispersion liquid 28 in which each electrophoretic particle 24 is dispersed is preferably a high resistance liquid. Here, “high resistance” indicates that the volume resistivity is 10 ⁷ Ω · cm or more, preferably 10 ¹⁰ Ω · cm or more, more preferably 10 ¹² Ω · cm or more.

  Specific examples of high-resistance liquids include hexane, cyclohexane, toluene, xylene, decane, hexadecane, kerosene, paraffin, isoparaffin, silicone oil, dichloroethylene, trichloroethylene, perchloroethylene, high-purity petroleum, benzine, diisopropylnaphthalene, and olive oil. , Trichlorotrifluoroethane, tetrachloroethane, dibromotetrafluoroethane, and the like, and mixtures thereof can be suitably used.

  In addition, to the high-resistance liquid, an acid, an alkali, a salt, a dispersion stabilizer, a stabilizer, an antibacterial agent, a preservative, and the like can be added for the purpose of preventing oxidation or absorbing ultraviolet rays. It is preferable to add so that it may become the range of the specific volume resistance value shown by.

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

  More specific examples of the ionic and nonionic surfactants are as follows. Nonionic activators include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, And fatty acid alkylolamide. Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonic acid of higher fatty acid ester, and the like. Examples of the cationic surfactant include primary to tertiary amine salts and quaternary ammonium salts. These charge control materials are preferably 0.01% by weight or more and 20% by weight or less, particularly preferably in the range of 0.05 to 10% by weight with respect to the solid content of the particles. If it is less than 0.01% by weight, the desired charge control effect is insufficient, and if it exceeds 20% by weight, an excessive increase in conductivity of the dispersion is caused.

  Examples of the electrophoretic particles 24 and the colored particles 26 dispersed in the dispersion liquid 28 include glass beads, metal oxide particles such as alumina and titanium oxide, thermoplastic or thermosetting resin particles, and the surfaces of these resin particles. And those having a colorant fixed thereto, particles containing a colorant in a thermoplastic or thermosetting resin, and metal colloidal particles having a plasmon coloring function.

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

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

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

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

  An external additive may be attached to the surface of the particles as necessary. The color of the external additive is preferably transparent so as not to affect the color of the particles. As the external additive, inorganic particles such as metal oxides such as silicon oxide (silica), titanium oxide, and alumina are used. In order to adjust the charging property, fluidity, and environment dependency of the particles, they can be surface-treated with a coupling agent or silicone oil. Coupling agents include positively chargeable ones such as aminosilane coupling agents, aminotitanium coupling agents, nitrile coupling agents, and silanes that do not contain nitrogen atoms (consisting of atoms other than nitrogen). There are negatively charged ones such as coupling agents, titanium-based coupling agents, epoxy silane coupling agents, and acrylic silane coupling agents. Silicone oil includes positively charged ones such as amino-modified silicone oil, dimethyl silicone oil, alkyl-modified silicone oil, α-methylsulfone-modified silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone. Examples include negatively chargeable oils.

  As a method for producing each electrophoretic particle 24, any conventionally known method may be used. For example, as described in JP-A-7-325434, the resin, the pigment, and the 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, After cooling, a method of preparing particles using a pulverizer such as a jet mill, a hammer mill, a turbo mill, etc., and then dispersing the obtained particles in a dispersion medium can be used. Also, particles containing a charge control agent are prepared by polymerization methods such as suspension polymerization, emulsion polymerization, dispersion polymerization, coacervation, melt dispersion, emulsion aggregation, and then dispersed in a dispersion medium. A particle dispersion medium may be prepared. Furthermore, the resin can be plasticized, the dispersion medium does not boil, and the resin, the colorant, the charge control agent and the dispersion medium are at a temperature lower than the decomposition point of the resin, the charge control agent and / or the colorant. There are methods using suitable equipment that can disperse and knead the raw materials. Specifically, the pigment, the resin, and the charge control agent are heated and melted in a dispersion medium with a meteor mixer, a kneader, etc., and the molten mixture is cooled with stirring using the temperature dependence of the solvent solubility of the resin. The particles can be made by solidification / precipitation.

  On the other hand, the voltage application device 14 is connected to each of the surface electrode 36 and the back electrode 40, and an electric field is formed between the substrates by applying a voltage to the surface electrode 36 and the back electrode 40 by the voltage application device 14. The

  The voltage application device 14 is connected to a drive control device 18, and an image signal output device 16 is connected to the drive control device 18. The drive control device 18 includes a CPU, a ROM, a RAM, a hard disk, and the like, and the CPU displays an image on the display device 10 according to a program stored in the ROM, the hard disk, or the like. The image signal output device 16 may apply a hard disk or the like to store and output a display image for displaying an image on the electrophoretic display element 12. That is, the drive control device 18 controls the voltage application device 14 according to the display image stored in the image signal output device 16 to apply a voltage between the substrates, so that each electrophoretic particle 24 corresponds to the voltage. Move and display the image. The display image stored in the image signal output device 16 may be taken into the image signal output device 18 via various recording media such as a CD-ROM and a DVD and a network.

  Each electrophoretic particle 24 maintains its state when a voltage is applied, even after the application of the voltage between the substrates is stopped, by an adhesion force such as van der Waals force or mirror image force.

  By the way, in a display device including a plurality of types of electrophoretic particles 24, there is a technique for moving desired particles using a difference in moving speed. However, in practice, color mixing occurs because particles having a high moving speed reach the substrate first.

  For example, as shown in FIG. 2, when three positively charged particles of red (R) color, G (green) color, and B (blue) color are encapsulated and the respective moving speeds are R> B> G, When the voltage of the front electrode 36 is set to 0 and a voltage of + V is applied to the back electrode, as shown in FIG. 2A, the moving speed is high in the order of R color, B color, and G color. It reaches the back substrate 22 and is laminated in the order of R color, B color, and G color. Then, when a voltage of -V is applied to the surface electrode from this state and the voltage of the back electrode 40 is set to 0, as shown in FIG. However, some of the slow particles reach the substrate before the fast particles, and color mixing occurs as shown in FIG.

  Therefore, in the present embodiment, in order to prevent such color mixture, the electrophoretic particles 24 are moved so as to form aggregates on the substrate when displaying colors that are likely to generate color mixture. . The term “on the substrate” means a surface in contact with the substrate (the display substrate 20 or the back substrate 22).

  Specifically, the cyan migrating particles 24C and the magenta migrating particles 24M are charged with opposite polarities as described above. The voltage V2 separates and moves in opposite directions, and the voltage V1 (V2> V1) or less encloses the electrophoretic particles 24 that form an aggregate and move.

  For example, when a voltage of + V2 is applied to the front electrode 36 and the voltage of the back electrode 40 is set to 0, as shown in FIG. 3A, the cyan migrating particles 24C move to the display substrate 20 side, and the magenta migrating particles 24M. Moves to the back substrate 22 side, so that cyan migrating particles 24C are observed from the display substrate 20 side, and cyan is displayed.

  On the other hand, when the voltage of the front electrode 36 is set to −V2 and a voltage of 0 is applied to the back electrode 40, as shown in FIG. 3B, the magenta migrating particles 24M move to the display substrate 20 side, and the cyan migrating particles 24C are moved. Since it moves to the back substrate 22 side, the magenta migrating particles 24M are observed from the display substrate 20 side, and the magenta color is displayed.

  Further, when cyan is displayed (the state shown in FIG. 3A), when the voltage of the front electrode 36 is set to 0 and a voltage of + V1 is applied to the back electrode 40, as shown in FIG. The particles 24C move to the back substrate 22 side, the cyan electrophoretic particles 24C and the magenta electrophoretic particles 24M form aggregates on the back substrate 22 side, and white particles 26 are observed from the display substrate 20 side. In this state, if the voltage of the surface electrode 36 is + V1 and the voltage of the back electrode 40 is 0, the cyan migration particles 24C and the magenta migration particles 24M are aggregated as shown in FIG. To move to blue. Since it moves to the display substrate 20 side in the aggregation state, color mixing is suppressed.

  Further, even when magenta is displayed (the state shown in FIG. 3B), the voltage of the back electrode 40 is set to 0 and a voltage of + V1 is applied to the surface electrode 36, as shown in FIG. The cyan particles 24 move to the display substrate 20 side, the magenta migrating particles 24M and the cyan migrating particles 24C form aggregates on the display substrate 20 side, and blue is observed from the display substrate 20 side. In this state, when the voltage of the front substrate 36 is set to 0 and a voltage of + V is applied to the back electrode 30, the back substrate 22 is in a state where the magenta migrating particles 24M and the cyan migrating particles 24C are aggregated as shown in FIG. Move to the side and display in white. Since it moves to the back substrate 22 side in the aggregation state, color mixing is suppressed.

  Thus, in the present embodiment, a voltage is applied so that the cyan migrating particles 24C and the magenta migrating particles 24M form aggregates on the substrate, or the electrophoretic particles 24 move in an aggregated state. By applying a voltage in between, color mixing is suppressed.

  In addition, since the two types of electrophoretic particles 24 charged with opposite polarities can be simultaneously moved in the same direction, the response speed is higher than when the two types of electrophoretic particles 24 are not aggregated. For example, as shown in FIG. 3C, the cyan electrophoretic particles 24C and the magenta electrophoretic particles 24C and the magenta electrophoretic particles 24M are moved from the white display to the back substrate 22 side, as shown in FIG. When 24M is changed to the blue display moved to the display substrate 20 side, when the two types of electrophoretic particles 24 are not aggregated, the voltage of the surface electrode 36 is set to -V2 as shown in FIG. After the voltage of 40 is set to 0 and the magenta migrating particles 24M are moved to the display substrate 20 side while leaving the cyan migrating particles 24C on the back substrate 22 side, the voltage of the surface electrode 36 is shown in FIG. Needs to be + V1 and the voltage of the back electrode 40 is set to 0 to move the cyan migrating particles to the display substrate 20 side. When two types of particles aggregate, it is only necessary to set the voltage of the surface electrode 36 to + V1 and the voltage of the back electrode 40 to 0 as described above, and the response speed becomes high.

  Further, in the state where the magenta electrophoretic particles 24M and the cyan electrophoretic particles 24C are aggregated, the apparent particle diameter of the aggregates is large, so that the moving speed of the particles is faster and the response speed is faster than in the non-aggregated state. .

  In addition, when applying a voltage so that the electrophoretic particles 24 aggregate on the substrate, the electrophoretic particles 24 may be vibrated by further applying an alternating voltage or the like to improve the cohesive force. .

  In the above embodiment, the moving speed may be the same or different. However, using one of the electrophoretic particles 24 having different moving speeds (response speeds), only one of the electrophoretic particles moves. Two types of electrophoretic particles are aggregated.

  Furthermore, as shown in FIG. 4A, a voltage may be applied to aggregate the electrophoretic particles 24 between the substrates to move the electrophoretic particles 24 in an aggregated state. The particle density at the time of contact is smaller than that of aggregation on the substrate, and electrophoretic particles 24 that move in opposite directions and are not aggregated are generated. On the other hand, in the present embodiment, as shown in FIG. 4B, the contact density of the electrophoretic particles 24 becomes higher by aggregating on the substrates than when forming an aggregated state between the substrates. Further, since the particle movement is reduced (one electrophoretic particle 24 stops or moves at a low speed), an aggregated state is reliably formed.

  Here, a specific color display process of the display device 10 will be described with an example. FIG. 5 is a flowchart showing an example of the color display processing flow of the display device 10 according to the embodiment of the present invention. In the following processing, an example in which the cyan state shown in FIG. 4A is the initial state is shown as the initial state, but the present invention is not limited to this, and the magenta color may be the initial state.

  In step 100, the initial state is displayed and the process proceeds to step 102. That is, the drive control device 18 controls the voltage application device 14 so that a voltage of + V2 is applied to the surface electrode 36 and the voltage of the back electrode 40 becomes zero. That is, the negatively charged cyan electrophoretic particles 24C move to the display substrate 20 side, and the positively charged magenta electrophoretic particles 24M move to the back substrate 22 side, so that a cyan color is displayed.

  In step 102, it is determined whether or not the display is blue. In the determination, the drive control device 18 determines whether or not the color of the image output from the image signal output device 16 is blue. If the determination is affirmative, the process proceeds to step 104, and if the determination is negative. Goes to step 108.

  In step 104, the voltage application device 14 is controlled by the drive control device 18 so that the voltage of the front electrode 36 is 0 and the rear electrode 40 becomes + V1, and the process proceeds to step 106. As a result, the cyan migrating particles 24C move to the back substrate 22 side, and the cyan migrating particles 24C and the magenta migrating particles 24M form aggregates on the back substrate 22.

  In step 106, the voltage application device 14 is controlled by the drive control device 18 so that the voltage of the back electrode 40 becomes 0 by applying a voltage of + V1 to the surface electrode 36, and a series of processing is returned. That is, in a state where the cyan migrating particles 24C and the magenta migrating particles 24M form aggregates, the cyan migrating particles 24C move to the display substrate 20 side and display blue. At this time, since the aggregates are formed and moved, the particles move together and color mixing is suppressed.

  On the other hand, in step 108, it is determined whether or not white display is performed. In the determination, the drive control device 18 determines whether or not the color of the image output from the image signal output device 16 is white. If the determination is affirmative, the process proceeds to step 110, and if the determination is negative. Goes to step 112.

  In step 110, the voltage application device 14 is controlled by the drive control device 18 so that the voltage of the surface electrode 36 is 0 and the back electrode 40 becomes + V1, and a series of processing is returned. As a result, the cyan migrating particles 24C move to the back substrate 22 side, the cyan migrating particles 24C and the magenta migrating particles 24M form aggregates on the back substrate 22, and white is displayed. At this time, since the aggregate is formed on the back substrate 22, the electrophoretic particles 24 floating between the substrates are eliminated, and color mixing is suppressed.

  In step 112, it is determined whether the display is magenta. In this determination, the drive control device 18 determines whether or not the color of the image output from the image signal output device 16 is magenta. If the determination is affirmative, the process proceeds to step 114; A series of processing is returned as the initial cyan display.

  In step 114, the voltage application device 14 is controlled by the drive control device 18 so that the voltage of the back electrode 40 becomes 0 by applying a voltage of -V2 to the surface electrode, and a series of processing is returned. That is, the positively charged magenta electrophoretic particles 24M move to the display substrate 20 side, and the negatively charged cyan electrophoretic particles 24C move to the back substrate 22 side, so that a magenta color is displayed.

  In the present embodiment, by performing such control, four-color display of cyan, white, magenta, and blue is performed. Further, when displaying white or blue, the cyan electrophoretic particles 24C and the magenta electrophoretic particles 24M form aggregates on the substrate, so that color mixing is suppressed.

  In the above color display processing, the cyan migrating particles 24C and the magenta migrating particles 24M are moved from the aggregated state to the display substrate 20 side in the aggregated state on the back substrate 40 side. For example, a voltage may be applied so that the cyan migrating particles 24C move to the display substrate 20 side from the state of displaying magenta color, and the particles may be aggregated on the display substrate 20 side.

  Subsequently, a result of verifying the effect when the above-described display device 10 is specifically configured and aggregated on the substrate will be described below.

  First, the preparation of the dispersion A of the white particles 26 sealed in the display device 10 will be described.

  In a 100 ml three-necked flask equipped with a reflux condenser, 5 parts by weight of 2-vinylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.), 5 parts by weight of silicone macromer FM-0721 (manufactured by Chisso Corporation), lauroyl peroxide as an initiator 0.3 parts by weight (manufactured by Wako Pure Chemical Industries, Ltd.) and 20 parts by weight of silicone oil KF-96L-1CS (manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and bubbling with nitrogen gas was performed for 15 minutes. Polymerization was carried out at 24 ° C. for 24 hours.

  The obtained white particles were prepared with a silicone oil to a solid content concentration of 40 wt% to obtain a white particle dispersion A. At this time, the particle diameter of the white particles was 450 nm.

  Next, preparation of the dispersion M1 of the magenta migrating particles 24M will be described.

  Silaplane FM-0711 (manufactured by Chisso Corporation) 95 parts by mass, methyl methacrylate: 3 parts by mass, glycidyl methacrylate 2 parts by mass are mixed with silicone oil: 50 parts by mass, and azobisvaleronitrile 0.5 is added as a polymerization initiator. A silicone polymer A was produced by adding a part by mass and polymerizing. The produced silicone polymer A was dissolved in 3% by mass in dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96-2cs) to prepare a 3% by mass silicone oil solution of silicone polymer A.

  Next, a copolymer (weight average molecular weight 60,000) having a mass ratio of N-vinylpyrrolidone and N, N-diethylaminoethyl acrylate of 9/1 was synthesized by radical solution polymerization.

  Next, 3 parts by mass of a 10% aqueous solution of the copolymer is mixed with 1 part by mass of a magenta pigment (manufactured by Ciba: Unisperse), and this mixed solution is mixed with 10 parts by mass of a 3% silicone oil solution of the silicone polymer A. The mixture was stirred for 10 minutes with an ultrasonic crusher to prepare a suspension in which an aqueous solution containing a polymer having a charged group and a pigment was dispersed and emulsified in silicone oil.

  Next, after removing water at 2 kPa and 70 ° C., the suspension was heated at 100 ° C. for 3 hours to obtain a silicone oil dispersion in which magenta particles were dispersed. Next, butyl bromide corresponding to 50% of the molar amount of N, N-diethylaminoethyl acrylate in the particle solid content is added to the dispersion and heated at 80 ° C. for 3 hours. Washing and classification were performed to adjust the solid content concentration to 4 wt%, and a magenta electrophoretic particle dispersion M1 was produced. The produced magenta color particles had a volume average particle size of 400 nm (manufactured by Otsuka Electronics Co., Ltd., measured with FPAR-1000) and were positively charged in silicone oil.

  Next, the synthesis of the magenta particle dispersion M2 used in the comparative example will be described.

  12 parts by mass of Silaplane FM-0725 (manufactured by Chisso) as the first silicone monomer, 36 parts by mass of Silaplane FM-0721 (manufactured by Chisso) as the second silicone monomer, phenoxyethylene glycol acrylate (Shin Nakamura Chemical Co., Ltd.) AMP-10G) 20 parts by mass, hydroxyethyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 32 parts by mass are mixed with isopropyl alcohol (IPA) 300 parts by mass, and AIBN (2,2-azobisisobutyl is used as a polymerization initiator. Nitrile) 1 part by mass was dissolved and polymerized under nitrogen at 70 ° C. for 6 hours. The resulting product was purified and dried using hexane as a reprecipitation solvent to obtain a silicone polymer B.

  Further, 0.5 g of the above silicone polymer B was added to 9 g of isopropyl alcohol (IPA) and dissolved, then 0.5 g of magenta pigment (Pigment Red 3090) was added, and 0.5 mmΦ zirconia balls were used. It was dispersed for 48 hours to obtain a pigment-containing polymer solution.

 3 g of this pigment-containing polymer solution was taken out and heated to 40 ° C., and then 12 g of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF96-2cs) was dropped little by little while applying ultrasonic waves. The polymer was deposited on the pigment surface. Thereafter, the solution was heated to 60 ° C. and dried under reduced pressure to evaporate IPA to obtain magenta particles having a silicone polymer adhered to the pigment surface. The obtained magenta particles were washed and classified using a centrifugal separator to adjust the solid content concentration to 4 wt%, thereby preparing a magenta migrating particle dispersion M2. The produced magenta particles had a volume average particle size of 200 nm (manufactured by Otsuka Electronics Co., Ltd., measured with FPAR-1000) and were positively charged in silicone oil.

  Subsequently, the synthesis of the dispersion liquid C1 of the cyan migrating particles 24C will be described.

  19 parts by mass of Silaplane FM-0725 (manufactured by Chisso) as the first silicone monomer, 29 parts by mass of Silaplane FM-0721 (manufactured by Chisso) as the second silicone monomer, methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) ) 9 parts by mass, 5 parts by mass of octafluoropentyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) and 38 parts by mass of hydroxyethyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed with 300 parts by mass of isopropyl alcohol (IPA), As a polymerization initiator, 1 part by weight of AIBN (2,2-azobisisobutylnitrile) was dissolved, and polymerization was performed at 70 ° C. for 6 hours under nitrogen. The resulting product was purified using hexane as a reprecipitation solvent and dried to obtain silicone polymer C.

In the preparation of the magenta electrophoretic particle dispersion M2, silicone polymer C was used instead of silicone polymer B, and cyan pigment (Sanyo Dye, cyanine blue 4973) was used instead of magenta pigment. A cyan electrophoretic particle dispersion C1 was prepared in the same manner as the synthesis of the magenta electrophoretic particle dispersion M2. The obtained cyan particles had a volume average particle size of 300 nm (manufactured by Otsuka Electronics Co., Ltd., measured with FPAR-1000) and were negatively charged.
(Comparative Example 1)
An ITO film having a thickness of 50 nm was formed by sputtering as an electrode on a glass substrate having a thickness of 0.7 mm. Furthermore, CYTOP (manufactured by Asahi Glass Co., Ltd.) was applied on ITO with a thickness of 80 nm by a spin coating method. Two substrates were prepared and used as a display substrate 20 and a back substrate 22. The back substrate 22 was overlaid on the display substrate 20 using a 50 μm Teflon (registered trademark) sheet as a spacer, and fixed with a clip.

  Thereafter, a mixed liquid obtained by mixing white particle dispersion A: 50 parts by mass, dispersion liquid C1: 25 parts by mass of cyan electrophoretic particles 24C, and dispersion liquid M2: 25 parts by mass of magenta electrophoretic particles 24M is used as a spacer part of the substrate. This was injected to obtain an evaluation cell.

  Using the evaluation cell thus produced, a potential difference of 30 V was applied between the electrodes for 5 seconds so that the surface electrode 36 was positive. The dispersed negatively charged cyan electrophoretic particles 24C move to the positive electrode, that is, the surface electrode 36 side, and the positively charged magenta electrophoretic particles 24M move to the negative side electrode, that is, the back electrode 40 side. When observed from the side, a cyan color was observed.

  Thereafter, when a potential difference of 30 V is applied between the electrodes for 5 seconds so that the surface electrode 36 becomes negative, the positively charged magenta migrating particles 24M move to the negative electrode, that is, the surface electrode 36 side, and are negatively charged. The cyan migrating particles 24C moved to the positive electrode, that is, the back electrode 40 side, and a magenta color was observed when observed from the display substrate 20 side.

  Thereafter, when a potential difference of 30 V was applied between the electrodes for 0.5 second so that the surface electrode 36 became positive, both the magenta migrating particles 24M and the cyan migrating particles 24C were separated from the substrate. Thereafter, when a voltage of 15 V is applied for 5 seconds, the magenta migrating particles 24M and the cyan migrating particles 24C form aggregates between the electrodes, and move to the surface electrode 36 side, that is, the plus side electrode as aggregates. When observed from the substrate 20 side, a blue color was observed.

  Thereafter, when a potential difference of 15 V is applied between the electrodes so that the surface electrode 36 becomes negative, the aggregate of the magenta migrating particles 24M and the cyan migrating particles 24C moves to the back electrode 40 side, that is, the plus side electrode. When observed from the display substrate 20 side, white color was observed.

When the color density in the white display state was measured by X-Rite, the reflectance was 24%.
Example 1
ITO as an electrode was formed on a substrate made of glass with a thickness of 0.7 mm to a thickness of 50 nm by sputtering. Furthermore, CYTOP (manufactured by Asahi Glass Co., Ltd.) was applied on ITO with a thickness of 80 nm by a spin coating method. Two substrates were prepared and used as a display substrate 20 and a back substrate 22. The back substrate 22 was overlaid on the display substrate 20 using a 50 μm Teflon (registered trademark) sheet as a spacer, and fixed with a clip.

  Thereafter, a mixed liquid obtained by mixing 50 parts by mass of the dispersion liquid A of white particles 26, 1:25 parts by mass of the dispersion liquid C1 of cyan migration particles 24C, and 1:25 parts by mass of the dispersion liquid M1: magenta migration particles 24M is used as a spacer for the substrate. The cell for evaluation was used as an evaluation cell.

  Using the evaluation cell thus fabricated, a potential difference of 30 V was applied between the electrodes for 5 seconds so that the surface electrode 36 was positive. The dispersed negatively charged cyan particles move to the positive side electrode, that is, the surface electrode 36 side, and the positively charged magenta electrophoretic particles 24M move to the negative side electrode, that is, the back electrode 40 side. Was observed.

  Thereafter, when a potential difference of 30 V is applied between the electrodes for 5 seconds so that the surface electrode 36 becomes negative, the positively charged magenta migrating particles 24M move to the negative electrode, that is, the surface electrode 36 side, and negatively charged cyan particles. Moved to the positive electrode, that is, the back electrode 40 side, and a magenta color was observed when observed from the display substrate 20 side.

  After that, when a potential difference of 10 V was applied between the electrodes for 5 seconds so that the surface electrode 36 becomes positive, the cyan migrating particles 24C moved to the surface electrode 36 side, but the magenta migrating particles 24M moved from the display substrate 20. The cyan migrating particles and the magenta migrating particles 24M were aggregated on the display substrate 20. At this time, when observed from the display substrate 20 side, blue was observed.

  Thereafter, when a potential difference of 15 V is applied between the electrodes so that the surface electrode 36 is negative, the magenta electrophoretic particles 24M and the cyan electrophoretic particles 24C form aggregates, and the back electrode 40 side, that is, the positive side is formed. When moved to the electrode and observed from the display substrate 20 side, white color was observed.

  When the color density of this white display state was measured with X-Rite 404, the reflectance was 28%. The reflectance is improved as compared with the case where the particles are aggregated between the substrates as in Comparative Example 1. That is, when the particles are not aggregated on the substrate, cyan particles that do not aggregate are generated and become mixed color, and it is understood that the color mixture is suppressed by aggregating the particles on the substrate.

In the first embodiment, when blue is displayed from the state where the magenta color is displayed, it may be driven by applying an AC voltage in addition to the DC voltage. As a result, the electrophoretic particles 24 aggregate while vibrating, so that the cohesive force is improved and the white reflectance is improved.
(Second embodiment)
An ITO film having a thickness of 50 nm was formed by sputtering as an electrode on a glass substrate having a thickness of 0.7 mm. Furthermore, CYTOP (manufactured by Asahi Glass Co., Ltd.) was applied on ITO with a thickness of 80 nm by a spin coating method. Two substrates were prepared and used as a display substrate 20 and a back substrate 22. The back substrate 22 was overlaid on the display substrate 20 using a 50 μm Teflon (registered trademark) sheet as a spacer, and fixed with a clip.

  Thereafter, a mixed liquid obtained by mixing white particle dispersion A: 50 parts by mass, dispersion liquid C1: 25 parts by mass of cyan electrophoretic particles 24C, and dispersion liquid M1: 25 parts by mass of magenta electrophoretic particles 24M is used as a spacer part of the substrate. This was injected to obtain an evaluation cell.

  Using the evaluation cell thus produced, a potential difference of 30 V was applied between the electrodes for 5 seconds so that the surface electrode 36 was positive. The dispersed negatively charged cyan electrophoretic particles 24C move to the positive electrode, that is, the surface electrode 36 side, and the positively charged magenta electrophoretic particles 24M move to the negative side electrode, that is, the back electrode 40 side, from the display substrate 20 side. When observed, a cyan color was observed.

  Thereafter, when a potential difference of 30 V is applied between the electrodes for 5 seconds so that the surface electrode 36 becomes negative, the positively charged magenta migrating particles 24M move to the negative electrode, that is, the surface electrode 36 side, and are negatively charged. The cyan migrating particles 24C moved to the positive electrode, that is, the back electrode 40 side, and a magenta color was observed when observed from the display substrate 20 side.

  After that, when a potential difference of 10 V was applied between the electrodes for 5 seconds so that the surface electrode 36 becomes positive, the cyan migrating particles 24C moved to the surface electrode 36 side, but the magenta migrating particles 24M moved from the display substrate 20. Instead, the cyan migrating particles 24C and the magenta migrating particles 24M aggregated on the display substrate 20. At this time, when observed from the display substrate 20 side, blue was observed.

  Thereafter, an alternating electric field having a potential difference of 10 V was applied between the electrodes for 5 cycles at a frequency of 5 Hz, and then a potential difference of 15 V was applied between the electrodes for 5 seconds so that the surface electrode 36 was negative. While the cyan migrating particles 24C formed aggregates, they moved to the back electrode 40 side, that is, the plus side electrode, and when observed from the display substrate 20 side, white color was observed.

  When the color density of this white display state was measured with X-Rite 404, the reflectance was 30%.

  In this way, the reflectance is increased by applying the alternating electric field. That is, it can be seen that particles that do not aggregate can be further reduced by causing the particles to vibrate and collide with an alternating electric field.

  In the above-described embodiment, an example in which two types of electrophoretic particles 24 charged to opposite polarities and white particles 26 that are not charged are enclosed between substrates is not limited to this. In addition to the types of electrophoretic particles 24, electrophoretic particles 24 having different colors and threshold characteristics may be further encapsulated.

  In the above embodiment, the drive control device 18 controls the voltage application device 14 to control the movement of the electrophoretic particles 24 (the voltage is controlled so as to aggregate). However, the present invention is not limited to this. Instead, the movement control of the electrophoretic particles 24 performed by the drive control device 18 may be performed by the computer executing the program using the movement control of the electrophoretic particles 24 as a program.

  In the above embodiment, the example in which cyan and magenta colors are enclosed between the substrates as the colors of the electrophoretic particles 24 has been described. However, the present invention is not limited to this. You may make it apply.

DESCRIPTION OF SYMBOLS 10 Display apparatus 12 Electrophoretic display element 14 Voltage application apparatus 18 Drive control apparatus 20 Display substrate 22 Back surface substrate 24 Electrophoretic element 24C Cyan electrophoretic particle 24M Magenta electrophoretic particle 36 Surface electrode 40 Back electrode

Claims (7)

At least one of the particles is sealed between a pair of light-transmitting substrates and has different optical characteristics. At least one type of particles is charged with at least two types of particles that are opposite in polarity to the polarity of the other types of particles. A first electrode having a light transmitting property provided on one substrate side having a light transmitting property of the substrate, a second electrode provided on the other substrate side facing the first electrode, For display media with
The first electrode and the second electrode are formed such that, on one of the pair of substrates, at least two of the two or more types of particles that are oppositely charged to each other form an aggregate. A writing apparatus for writing an image on the display medium by applying a voltage therebetween.   The two types of particles form aggregates at a predetermined first voltage or less and move as aggregates, and the aggregates are separated at a second voltage higher than the first voltage, and are opposite to each other. The writing device according to claim 1, which moves in a direction.   The two types of particles have different threshold voltages for moving between the substrates, and particles having a lower threshold voltage than a threshold voltage of particles having a higher threshold voltage move to form aggregates. The writing device according to claim 2.   The writing apparatus according to claim 1, wherein the at least two kinds of particles have different moving speeds. At least one of the particles is sealed between a pair of light-transmitting substrates and has different optical characteristics. At least one type of particles is charged with at least two types of particles that are opposite in polarity to the polarity of the other types of particles. ,
A first electrode having translucency provided on one substrate side having translucency of the substrate;
A second electrode provided on the other substrate side facing the first electrode;
Between the first electrode and the second electrode, on at least one of the pair of substrates, at least two kinds of the two or more kinds of particles charged with opposite polarities form an aggregate. Control means for controlling the voltage applied to
A display device comprising: A pair of substrates, at least one of which is translucent,
When encapsulated between the pair of substrates, different in optical characteristics, and charged with opposite polarities, and a voltage equal to or lower than a predetermined first voltage is applied between the pair of substrates. , When an aggregate is formed on one of the pair of substrates to move as the aggregate, and a second voltage greater than the first voltage is applied between the pair of substrates, Two types of particles in which the aggregates separate and move in opposite directions;
A display medium comprising: At least one of the particles is sealed between a pair of light-transmitting substrates and has different optical characteristics. At least one type of particles is charged with at least two types of particles that are opposite in polarity to the polarity of the other types of particles. A first electrode having a light transmitting property provided on one substrate side having a light transmitting property of the substrate, a second electrode provided on the other substrate side facing the first electrode, An application means for applying a voltage between the first electrode and the second electrode;
A process for controlling the applying means on one of the pair of substrates so that at least two of the two or more types of particles that are oppositely charged with each other form an aggregate. Display program to be executed.

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