JP5211556B2 - Display medium and display device - Google Patents

Description

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

Conventionally, image display media using colored particles are known as image display media that can be rewritten repeatedly (see, for example, Patent Documents 1 to 5).
The image display medium includes, for example, a pair of substrates and a group of particles sealed between the substrates so as to be movable between the substrates in accordance with an electric field formed between the pair of substrates. Further, a gap member for partitioning the substrates into a plurality of cells may be provided between the substrates for the purpose of preventing the particles from being biased to a specific region in the substrates.

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

  In this image display medium, by moving the encapsulated particles by applying a voltage between a pair of substrates, the color according to the amount of particles moved to one of the substrates and the color of the moved particles Images are displayed. That is, by applying a voltage with a strength for moving the particles to be moved between the substrates in accordance with the color and density of the image to be displayed, the particles to be moved are moved between the pair of substrates. An image corresponding to the color and density of the image to be displayed is displayed by moving to either side.

  In Patent Documents 1 to 5, in order to provide a display medium having excellent display stability and driving stability, the surface of the charged particles is made hydrophilic, the inner wall surface is made hydrophilic, and the dispersion medium is made hydrophobic. A charged film with a surface charge having a polarity opposite to that of the charged particles on the fixing surface on which the charged particles are gathered. Improvements such as a configuration in which a charge control agent is contained in the inner wall are made.

JP 2006-023711 A JP 2006-244917 A JP 2000-258805 A JP 2001-133815 A JP 2004-279647 A

  It is an object of the present invention to provide a display medium and a display device that can suppress image quality deterioration.

The above problem is solved by the following means. That is,
The invention according to claim 1 is a pair of substrates having electrodes, at least one of which is translucent and disposed with a gap, a dispersion medium sealed between the pair of substrates, A group of particles dispersed in the dispersion medium and moving in the dispersion medium in response to an electric field formed between the pair of substrates; and the pair of substrates provided on at least one of the opposing surfaces of the pair of substrates. The particle group is provided on at least one of the treatment layer formed by treating at least one of the opposing surfaces of the substrate with a treatment agent containing a silane coupling agent represented by the following general formula (1), and the pair of substrates. And a charge layer charged with a different charge polarity .

Formula (1) R ¹ —Si (OR ² ) ₃

(In the general formula (1), R ¹ represents a monovalent aliphatic hydrocarbon group having 7 or more carbon atoms, and R ² represents a monovalent aliphatic hydrocarbon group having 4 or less carbon atoms.)

The invention according to claim 2, wherein the charging layer, and at least one of the pair of substrates, a display medium according to claim 1, characterized in that provided between the processing layer.

The invention of claim 3 is the a rear substrate pair of substrates the display substrate, according to claim 1 or claim 2, wherein the treatment layer is provided on the facing surface of at least the display substrate side It is a display medium as described in above.

Invention, the charge layer, according to claim 3, wherein at least the display substrate side processing layer disposed on the opposite surface of that provided between the display substrate according to claim 4 Display media.

The invention according to claim 5 is the display medium according to any one of claims 1 to 4 , wherein the thickness of the treatment layer is in a range of 10 nm to 200 nm.

The invention according to claim 6 is a pair of substrates having electrodes, at least one of which is translucent and arranged with a gap, a dispersion medium sealed between the pair of substrates, A group of particles dispersed in the dispersion medium and moving in the dispersion medium in response to an electric field formed between the pair of substrates; and the pair of substrates provided on at least one of the opposing surfaces of the pair of substrates. The particle group is provided on at least one of the treatment layer formed by treating at least one of the opposing surfaces of the substrate with a treatment agent containing a silane coupling agent represented by the following general formula (1), and the pair of substrates. And a voltage applying means for applying a voltage between the pair of substrates. The display device has a charging layer charged with a different charging polarity .

Formula (1) R ¹ —Si (OR ² ) ₃

(In the general formula (1), R ¹ represents a monovalent aliphatic hydrocarbon group having 7 or more carbon atoms, and R ² represents a monovalent aliphatic hydrocarbon group having 4 or less carbon atoms.)

The invention according to claim 7 is characterized in that the particle group is composed of a plurality of kinds of particles having different absolute values of voltages necessary to move according to an electric field and colored in different colors. The display device according to claim 6 .

The invention according to claim 8, wherein the plurality of types of particles have a voltage range necessary for moving in response to the electric field for each kind, and to claim 7, wherein different of said voltage range to each other It is a display apparatus of description.

  According to the first aspect of the present invention, there is an effect that image quality deterioration is suppressed as compared with the case where the processing layer is not provided on at least one of the opposing surfaces of the substrate.

According to the first aspect of the present invention, compared to the case where no charging layer is provided, the surface of the substrate can be controlled with the amount of charge controlled, the drive control becomes stable, and the charging layer is provided. There is an effect of reducing the scattering of the particle group when the particle group that has been electrophoresed to the substrate side adheres to the substrate side.

According to the invention concerning Claim 2, there exists an effect that drive control becomes more stable.

According to the third aspect of the invention, the electric field for moving the particles adhering to the display substrate side to the other side is smaller than the case where the treatment layer is not provided on the opposing surface on the display substrate side. Even if it is formed, there is an effect of suppressing the particles from being held in a state of adhering to the display substrate side.

According to the fourth aspect of the present invention, compared to the case where no charging layer is provided between the treatment layer and the display substrate, the effect of suppressing the decrease in density and image quality over time during non-electric field formation is suppressed. Play.

According to the fifth aspect of the present invention, compared with the case where the thickness of the processing layer is outside the range defined in the fifth aspect , it is possible to drive with a low voltage and to suppress the deterioration of image quality.

According to the invention which concerns on Claim 6, there exists an effect of suppressing the image quality degradation of a display medium.

According to the invention concerning Claim 7, there exists an effect that multicolor display is made | formed by a single pixel.

According to the invention concerning Claim 8, there exists an effect that the color display which suppressed color mixing is made | formed.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol may be provided to the member which an action and a function bears the same function through all the drawings, and the overlapping description may be omitted.

  FIG. 1 is a schematic configuration diagram of a display device according to an embodiment. FIG. 2 is an explanatory diagram schematically illustrating a movement mode of the particle group when a voltage is applied between the substrates of the display medium of the display device according to the embodiment.

  As illustrated in FIG. 1, the display device 10 according to the embodiment includes a display medium 12, a voltage application unit 16 that applies a voltage to the display medium 12, and a control unit 18.

  The display medium 12 includes a display substrate 20 that serves as an image display surface, a rear substrate 22 that faces the display substrate 20 with a gap, and holds the substrates at a predetermined interval, and between the display substrate 20 and the rear substrate 22. The gap member 24 is configured to include a plurality of cells, a particle group 34 enclosed in each cell, and a large-diameter colored particle group 36 having optical reflection characteristics different from those of the particle group 34.

  The cell indicates a region surrounded by the display substrate 20, the back substrate 22, and the gap member 24. A dispersion medium 50 is enclosed in this cell. The particle group 34 (described in detail later) is composed of a plurality of particles. The particle group 34 is dispersed in the dispersion medium 50 and passes between the display substrate 20 and the back substrate 22 according to the electric field strength formed in the cell. It moves through the gap of the large-diameter colored particle group 36.

  In the present embodiment, a description will be given assuming that the particle group 34 enclosed in one cell has a predetermined color and is preliminarily prepared by being charged positively or negatively.

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

  Further, in this embodiment, in order to simplify the description, the present embodiment will be described using a diagram focusing on one cell. Hereinafter, each configuration will be described in detail.

  The display substrate 20 has a configuration in which a surface electrode 40 is laminated on a support substrate 38. The back substrate 22 has a configuration in which a back electrode 46 is laminated on a support substrate 44.

  The display substrate 20 or both the display substrate 20 and the back substrate 22 are translucent. Here, the translucency in the present embodiment indicates that the transmittance of visible light is 60% or more.

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

  For the surface electrode 40 and the back electrode 46, 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 used as a single layer film, a mixed film, or a composite film, and can be formed by vapor deposition, sputtering, coating, or the like. Moreover, the thickness is 100-2000 mm normally according to a vapor deposition method and sputtering method. The back electrode 46 and the front electrode 40 may be formed in a desired pattern, for example, a matrix shape or a stripe shape that enables passive matrix driving, by a conventionally known means such as etching of a conventional liquid crystal display medium or a printed circuit board. it can.

  Further, the surface electrode 40 may be embedded in the support substrate 38. Further, the back electrode 46 may be embedded in the support substrate 44. In this case, the materials of the support substrate 38 and the support substrate 44 are selected according to the composition of each particle of the particle group 34 and the like.

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

  In the above description, the case where both the display substrate 20 and the back substrate 22 are provided with electrodes (the front electrode 40 and the back electrode 46) has been described. However, only one of them is provided, and active matrix driving is performed. Also good.

  In order to enable active matrix driving, the support substrate 38 and the support substrate 44 may include a TFT (thin film transistor) for each pixel. Since it is easy to laminate wiring and mount components, it is desirable to form the TFT on the back substrate 22 instead of the display substrate.

  The opposite surface of the display substrate 20 and the rear substrate 22 (the opposite surfaces of the front electrode 40 and the rear electrode 46 in this embodiment) is subjected to a charging process so as to have a charging polarity different from the charging polarity of the particle group. Each of the charging layer 27 and the charging layer 29 is provided.

In the present embodiment, a case will be described where both the opposing surface of the display substrate 20 and the back substrate 22 are subjected to charging treatment so that the charging layer 27 and the charging layer 29 are provided on each of the opposing surfaces. . Further, in the case where the charging layer 27 and the charging layer 29 are provided, a configuration in which the charging layer (charging layer 27 or charging layer 29) is provided only on one of the opposing surfaces of the display substrate 20 and the back substrate 22 is provided. In other words, a configuration in which the charging layer 27 is provided at least on the opposing surface on the display substrate 20 side is preferable from the viewpoint of suppressing deterioration in image quality.

As described above, the charging layer 27 and the charging layer 29 are formed by performing a charging process on each of the display substrate 20 and the back substrate 22.
In the charging process, a negative charging process is performed when the particle group 34 is composed of positively charged particles, and a positive charging process is performed when the particle group 34 is composed of negatively charged particles.

This charging treatment is preferably performed by chemical treatment, and for example, it may be modified with an acidic group or a basic group. Specifically, for example, when a positive charge treatment is performed, the treatment is preferably performed using a basic compound, and when a negative charge treatment is performed, the treatment is preferably performed using an acidic compound. For example, when the treatment is performed with a basic compound, a basic group (for example, NH ₃ ⁺ ) is arranged on the surface and is positively charged. On the other hand, when the treatment is performed with an acidic compound, acidic groups (for example, SO ₃ ⁻ and COO ⁻ ) are arranged on the surface and are negatively charged.

As the basic compound for performing the positive charging treatment, for example, the following compounds can be used, but are not limited thereto.
・ Polylylamine hydrochloride
・ Poly (p-phenylene vinylene)
・ Poly (p-methylpyridinium vinylene)
・ Protonated poly (p-pyridine vinylene)
・ Poly (2-N-methylpyridinium acetylene)
・ Γ-Aminopropytriethoxysilane
N- [3- (trimethoxysilyl) propyl] ethylenediamine

As the acidic compound for performing the negative charging treatment, for example, the following compounds can be used, but are not limited thereto.
・ Sulfonated polyline
Poly (thiophene-3-acetic-acid)
・ Sulfonated polystyrene
・ Polyvinylsulfate potassium salt
Poly-4-vinylbenzyl- (N, N-diethyl-N-methyl-) ammonium iodide
・ Carboxyethylsilanetriol

  In order to process a substrate using these compounds, for example, it can be performed as follows. These compounds are dissolved in alcohol such as methanol, ethanol, and IPA, water, or a mixed solution of alcohol and water so as to be 0.01 wt% to 10 wt%, and the substrate is immersed in the solution for 1 minute to 60 minutes. . Thereafter, excess liquid adhering to the substrate is washed away with alcohol, water, or a mixture of alcohol and water. Thereafter, the substrate can be processed by drying at 100 to 150 ° C. for 5 to 60 minutes. When the compound is dissolved in alcohol, water, or a mixture of alcohol and water, it is also effective to add 0.01 wt% to 10 wt% of hydrochloric acid, acetic acid, aqueous ammonia and the like.

  Depending on the surface to be treated, a basic compound can be treated after treatment with an acidic compound. Of course, the reverse is possible.

  As described above, in this embodiment, chemical treatment (for example, modification with an acidic group or a basic group: specifically, for example, basic treatment is performed to charge the opposing surfaces of the display substrate 20 and the back substrate 22. Compound, treatment using an acidic compound) and charging using a polar group.

A treatment layer 21 and a treatment layer 23 are provided on the opposing surfaces of the display substrate 20 and the back substrate 22, respectively.
Specifically, the treatment layer 21 is provided on the charging layer 27 provided on the display substrate 20 (on the back substrate 22 side of the charging layer 27), and the charging layer 29 on the back substrate 22 (display of the charging layer 29). A treatment layer 23 is provided on the substrate 20 side.

  In the present embodiment, a case where the processing layers (each of the processing layer 21 and the processing layer 23) are provided on both the opposing surfaces of the display substrate 20 and the back substrate 22 will be described. 22 may be provided only on one of the opposing surfaces, and at least a configuration in which the processing layer 21 is provided on the opposing surface on the display substrate 20 side is preferable from the viewpoint of suppressing image quality degradation.

  In the present embodiment, the above-described charging process is performed on the opposing surfaces of the display substrate 20 and the back substrate 22 to form the charging layer 27 and the charging layer 29, respectively. The case where the treatment layer (treatment layer 21 and treatment layer 23) is provided on each of the layer 27 and the charge layer 29 will be described, but the charge treatment is not performed (the charge layer 27 and the charge layer 29 are not provided). A configuration in which a treatment layer is directly provided on the opposing surface may be employed. For example, each of the surfaces of the back substrate 22 facing the display substrate 20 is not subjected to the charging process, and the processing layer 21 and the processing layer 23 are directly provided on each of the facing surfaces. Good.

  Each of the treatment layer 21 and the treatment layer 23 is made of a treatment agent containing at least a silane coupling agent represented by the following general formula (1), or the opposite surfaces of the display substrate 20 and the back substrate 22 or the charge layer 29 and the charge layer. It is formed by treating 27 opposing surfaces.

Formula (1) R ¹ —Si (OR ² ) ₃

In the general formula (1), R ¹ represents a monovalent aliphatic hydrocarbon group having 7 to 18 carbon atoms, and R ² represents a monovalent aliphatic hydrocarbon group having 1 to 4 carbon atoms. Represents.

In the general formula (1), the number of carbon atoms of the aliphatic hydrocarbon group represented by R ¹ is 7 or more and 18 or less, preferably 8 or more and 18 or less, and preferably 12 or more and 18 or less. It is particularly preferred that

When the aliphatic hydrocarbon group has a carbon number in the range of 7 or more and 18 or less, when the treatment layer is formed, the treatment layer surface has water repellency, so that it is formed between the display substrate 20 and the back substrate 22. After the particle group 34 that has been electrophoresed by the applied electric field and migrated to the display substrate 20 side or the back substrate 22 side reaches the display substrate 20 side or the back substrate 22 side, the electric field that moves to the substrate on the opposite surface side is the substrate. Even when it is formed between the display substrate 20 and the back substrate 22, it is suppressed that the particle group 34 remains attached to the substrate side where the particles 34 have arrived.
On the other hand, when the number of carbon atoms of the aliphatic hydrocarbon group is less than 7, the adhesion force of the particle group 34 attached to the treatment layer 21 or the treatment layer 23 increases, and reaches the display substrate 20 side or the back substrate 22 side by electrophoresis. In some cases, it is difficult to move the particle group 34 toward the opposite substrate side by forming an electric field that moves the particle group 34 toward the opposite substrate side. Further, when the number of carbon atoms of the aliphatic hydrocarbon exceeds 18, the formed treatment layer is difficult to solidify, so that the adhesion force of the adhered particle group 34 is increased, and the display substrate 20 side or the back substrate 22 side is obtained by electrophoresis. In some cases, it is difficult for the particle group 34 that has reached the position to move to the opposite substrate side due to the formation of an electric field that moves to the opposite substrate side.

In the general formula (1), the aliphatic hydrocarbon group represented by R ¹ may be linear or branched as long as it has 7 to 18 carbon atoms as described above. It may be either substituted or unsubstituted.
Specifically, for example, n-octyl group, t-octyl group, 2-ethylhexyl group, 1,5 dimethylhexyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, diethylamino Examples include an ethyl group, a diethylaminopropyl group, a dibutylaminoethyl group, a butoxypropyl group, an ethoxyethoxyethyl group, and an n-hexyloxypropyl group.
Among these, n-dodecyl group, hexadecyl group, and okdadecyl group are preferably used for the reason of water repellency.

In the general formula (1), examples of the substituent that the aliphatic hydrocarbon group substituent represented by R ¹ may have include a phenyl group, an amino group, a thiol group, and a fluoro group. In the general formula (1), the number of carbon atoms of the aliphatic hydrocarbon group represented by R ² is 1 or more and 4 or less, and preferably 1 or more and 2 or less, as described above.

  When the aliphatic hydrocarbon group has a carbon number in the range of 1 or more and 4 or less, hydrolysis easily occurs, so that the treatment layer can be easily and firmly formed.

  On the other hand, when the number of carbon atoms is 0, there may be a problem that it is difficult to form a treatment layer. Moreover, when the carbon number of the aliphatic hydrocarbon exceeds 3, it is difficult to produce or obtain the compound itself.

In the general formula (1), as described above, the aliphatic hydrocarbon group represented by R ² may be linear or branched as long as it has 1 to 4 carbon atoms. Good.
Specifically, a substituted or unsubstituted linear or branched alkyl group having 1 to 4 carbon atoms (for example, methyl group, ethyl group, isopropyl group, n-propyl group, methoxyethyl group, ethoxyethyl group, etc.) It is done.
Among these, it is preferable to use a methyl group or an ethyl group because a thin film can be easily and firmly formed.

  The content of the silane coupling agent represented by the general formula (1) in the treatment agent for forming the treatment layer 21 and the treatment layer 23 is 0.01% by weight or more and 20% by weight or less. Preferably, it is more preferably 0.1 wt% or more and 10 wt% or less.

  When the content of the silane coupling agent represented by the general formula (1) in the treatment agent exceeds 20% by weight, there may be a problem that it is difficult to control the thickness of the treatment layer when forming the treatment layer. If the amount is 0.01% by weight or less, there may be a problem that a uniform treatment layer cannot be formed.

  By providing the processing layer 21 and the processing layer 23, the particle group 34 is easily detached from the display substrate 20 side or the back substrate 22 side, and the display substrate 20 side or the back surface is easily generated by an electric field formed between the substrates. After the particle group 34 moves to the substrate 22 side, when the electric field for moving the particle group 34 to the opposite substrate is formed between the substrates, the substrate side (display substrate 20 side) attached before the electric field formation is formed. Alternatively, it is considered that the particle group 34 can be prevented from remaining attached to the rear substrate 22 side). In this way, image quality deterioration can be suppressed regardless of the material constituting the surface of the particle group 34.

  The thickness of the treatment layer 21 and the treatment layer 23 is preferably in the range of 10 nm to 200 nm, more preferably in the range of 20 nm to 100 nm, and particularly preferably in the range of 20 nm to 50 nm. preferable.

When the thickness of the treatment layer 21 and the treatment layer 23 is less than 10 nm, the particle group 34 is easily peeled off due to the presence of the treatment layer 21 and the treatment layer 23 (the electric field for moving the particle group 34 to the opposite surface side is When formed between the substrates, the ease of movement from the substrate side attached before the formation of the electric field and moving to the opposite surface side) may be reduced, and image quality may be deteriorated.
On the other hand, when the thickness of the treatment layer 21 and the treatment layer 23 exceeds 200 nm, it is necessary to apply a high voltage between the substrates in order to move the particle group 34 between the substrates as compared with the case where the thickness is less than 200 nm. In some cases, the driving performance and response speed may be reduced.

  Examples of a method of providing the processing layer 21 and the processing layer 23 on the opposing surfaces of the display substrate 20 and the back substrate 22 include, for example, these compounds on the opposing surfaces of the display substrate 20 and the back substrate 22 that have been charged. Is dissolved in alcohol such as methanol, ethanol, and IPA, water, or a mixed solution of alcohol and water so as to be 0.01 wt% to 20 wt%, and the substrate is immersed in the solution for 1 minute to 60 minutes. Thereafter, excess liquid adhering to the substrate is washed away with alcohol, water, or a mixture of alcohol and water. Thereafter, the substrate can be processed by drying at 100 to 150 ° C. for 5 to 60 minutes. When the compound is dissolved in alcohol, water, or a mixture of alcohol and water, it is also effective to add 0.01 wt% to 10 wt% of hydrochloric acid, acetic acid, aqueous ammonia and the like. Alternatively, a method of providing a treatment agent containing these compounds by dip coating or spin coating is used.

  The gap member 24 for maintaining a gap between the display substrate 20 and the back substrate 22 is formed so as not to impair the light-transmitting property of the display substrate 20, and is a thermoplastic resin, a thermosetting resin, or an electron beam curing. It can be formed of resin, photo-curing resin, rubber, metal or the like.

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

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

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

  Note that “transparent” means having a transmittance of 60% or more with respect to visible light.

The dispersion medium 50 in which the particle group 34 is dispersed is desirably an insulating liquid. Here, “insulating” indicates that the volume resistivity is 10 ¹¹ Ωcm or more. The same applies hereinafter.

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

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

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

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

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

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

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

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

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

  Further, by mixing the following colorant in the dispersion medium 50, a color different from the color of the particle group 34 can be displayed on the display medium 12. For example, when the color of the particle group 34 is black by mixing a colorant showing white as the colorant, white and black can be displayed in the display medium 12.

  Examples of the colorant mixed in the dispersion medium 50 include carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan color material, azo-based yellow color material, azo-based magenta color material, quinacridone-based magenta color material, and red. Known colorants such as a color material, a green color material, and a blue color material can be listed. 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 cited as typical examples.

  Since the particle group 34 moves in the dispersion medium 50, if the viscosity of the dispersion medium 50 is equal to or higher than a predetermined value, the dispersion of the adhesion force to the back substrate 22 and the display substrate 20 is large, and the particle movement with respect to the electric field Since the threshold value cannot be taken, the viscosity of the dispersion medium 50 may be adjusted.

  The viscosity of the dispersion medium 50 is in the range of 0.1 mPa · s to 100 mPa · s in an environment at a temperature of 20 ° C., which is essential from the viewpoint of the moving speed of the particles, that is, the display speed. It is preferably 50 mPa · s, and more preferably 0.1 mPa · s to 20 mPa · s.

  By setting the viscosity of the dispersion medium 50 in the range of 0.1 mPa · sPa · s to 100 mPa · s, the adhesion between the particle group 34 dispersed in the dispersion medium 50 and the display substrate 20 or the back substrate 22 Variations in flow resistance and electrophoresis time can be suppressed.

  The viscosity of the dispersion medium 50 can be adjusted by adjusting the molecular weight, structure, composition, and the like of the dispersion medium. In addition, Tokyo Keiki B-8L type | mold viscosity meter can be used for the measurement of this viscosity.

The particle group 34 is composed of a plurality of particles, and each particle is positively or negatively charged, and is between the surface electrode 40 and the back electrode 46 (that is, between the display substrate 20, the back substrate 22, and the substrate). ), A predetermined voltage is applied, and an electric field of a predetermined electric field strength or higher is formed between the display substrate 20 and the rear substrate 22 to move in the dispersion medium 50.
The change in the display color on the display medium 12 is caused by the movement of each particle constituting the particle group 34 in the dispersion medium 50.

  Each particle of the particle group 34 includes glass beads, insulating metal oxide particles such as alumina, titanium oxide, and the like, thermoplastic or thermosetting resin particles, and a colorant fixed on the surface of these resin particles. And particles containing 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. Blue 15: 1, C.I. I. Pigment Blue 15: 3, etc. can be exemplified as typical ones.

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

A magnetic material may be mixed in the inside or the surface of the particles as necessary. As the magnetic material, a color-coated inorganic magnetic material or organic magnetic material is used as necessary. Further, a transparent magnetic material, in particular, a transparent organic magnetic material does not hinder the color development of the color pigment, and the specific gravity is smaller than that of the inorganic magnetic material, and is more desirable.
As the colored magnetic powder, for example, a small-diameter colored magnetic powder described in JP-A-2003-131420 can be used. A material provided with magnetic particles serving as nuclei and a colored layer laminated on the surface of the magnetic particles is used. The colored layer may be selected by coloring the magnetic powder opaque with a pigment or the like, but it is desirable 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 desirably transparent so as not to affect the color of the particles.

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

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

Of the above external additives, well-known hydrophobic silica and hydrophobic titanium oxide are desirable. 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. 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 1 nm to 100 nm, and are preferably 5 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. When the amount of the external additive added is too large, at least a part of the external additive is liberated from the particle surface and adheres to the surface of the other particle, so that desired charging characteristics cannot be obtained. In general, the amount of the external additive is preferably 0.01 to 3 parts by weight and more preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the particles.

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

  As a method for producing the particle group 34, any conventionally known method may be used. For example, as described in JP-A-7-325434, a resin, a pigment, and a charge control agent are weighed to a predetermined mixing ratio, and after the resin is heated and melted, the pigment is added, mixed, dispersed, and cooled. Then, a method of preparing particles using a pulverizer such as a jet mill, a hammer mill, a turbo mill, etc., and then dispersing the obtained particles in a dispersion medium can be used. Also, particles containing a charge control agent are prepared by polymerization methods such as suspension polymerization, emulsion polymerization, dispersion polymerization, coacervation, melt dispersion, emulsion aggregation, and then dispersed in a dispersion medium. A particle dispersion medium may be produced. Furthermore, the resin, the colorant, the charge control agent and the dispersion medium 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 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 produced 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 desired temperature range, for example, 80 A method of dispersing and kneading at ˜160 ° C. can be used. As granular media, steels such as stainless steel and carbon steel, alumina, zirconia, silica and the like are desirably used. In order to produce particles by this method, the raw material that has been previously fluidized is further dispersed in a container by means of granular media, and then the dispersion medium is cooled to precipitate a resin containing a colorant from the dispersion medium. The granular media generates a shear and / or impact to reduce the particle size while maintaining a motion state during and after cooling.

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

  The large-diameter colored particle group 36 is an uncharged particle group, is composed of large-diameter colored particles having optical reflection characteristics different from that of the particle group 34, and is a reflective member that displays a color different from that of the particle group 34. It functions. And it also has a function as a gap member to move without hindering movement between the display substrate 20 and the back substrate 22.

  Specifically, the large-diameter colored particle group 36 is, for example, colored in a particle size larger than each particle constituting the particle group 34 and different from the color of the particle group 34. It is a member for causing the display medium 12 to display a different color. In the present embodiment, the case where the large-diameter colored particle group 36 is white will be described, but the present invention is not limited to this color.

  The large-diameter colored particle group 36 uses, for example, particles in which a white pigment such as titanium oxide, silicon oxide, or zinc oxide is dispersed in polystyrene, polyethylene, polypropylene, polycarbonate, PMMA, acrylic resin, phenol resin, formaldehyde condensate, or the like. it can. Moreover, when applying particles other than white as the particles constituting the colored member, for example, the above-described resin particles containing a pigment or dye of a desired color can be used. If the pigment or dye is, for example, RGB or YMC color, a general pigment or dye used for printing ink or color toner can be used.

  In order to enclose the large-diameter colored particle group 36 between the substrates, for example, an inkjet method or the like is performed. When the large-diameter colored particle group 36 is fixed, for example, after enclosing the large-diameter colored particle group 36, the large-diameter colored particle group 36 is heated (and pressurized if necessary), and the particle group surface layer of the large-diameter colored particle group 36 This is performed while maintaining the particle gap.

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

  In order to fix the display substrate 20 and the back substrate 22 through the gap member 24, fixing means such as a combination of bolts and nuts, a clamp, a clip, and a frame for fixing the substrate can be used. Also, fixing means such as an adhesive, heat melting, and ultrasonic bonding can be used.

  The display medium 12 configured in this way is shared with bulletin boards, circular editions, electronic blackboards, advertisements, signboards, blinking signs, electronic paper, electronic newspapers, electronic books, and copiers / printers that can store and rewrite images. It can be used for document sheets that can be used.

  As described above, the display device 10 according to the embodiment of the present invention includes the display medium 12, the voltage application unit 16 that applies a voltage to the display medium 12, and the control unit 18. (See FIG. 1).

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

  The voltage application unit 16 is connected to the control unit 18 so as to be able to exchange signals.

  The control unit 18 stores in advance various programs such as a CPU (Central Processing Unit) that controls the operation of the entire apparatus, a RAM (Random Access Memory) that temporarily stores various data, and a control program that controls the entire apparatus. It is also possible to configure as a microcomputer including a ROM (Read Only Memory).

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

  Next, the operation of the display device 10 will be described. This operation will be described according to the operation of the control unit 18.

  Here, the case where the particle group 34 enclosed in the display medium 12 is black and is negatively charged will be described. In the following description, it is assumed that the dispersion medium 50 is transparent and the large-diameter colored particle group 36 is white. That is, in the present embodiment, the case where the display medium 12 displays black or white by the movement of the particle group 34 will be described.

First, an initial operation signal indicating that the voltage is applied for a predetermined time so that the surface electrode 40 is a negative electrode and the back electrode 46 is a positive electrode is output to the voltage application unit 16. When a negative electrode and a voltage equal to or higher than a threshold voltage at which the concentration variation ends is applied between the substrates, the particles constituting the particle group 34 charged in the negative electrode move to the back substrate 22 side, and are applied to the back substrate 22. (See FIG. 2A).
At this time, the color of the display medium 12 visually recognized from the display substrate 20 side is visually recognized as white as the color of the large-diameter colored particle group 36.

  The T1 time may be stored in advance in a memory such as a ROM (not shown) in the control unit 18 as information indicating the voltage application time in the voltage application in the initial operation. Then, information indicating the predetermined time may be read when the process is executed.

  Next, the polarity of the voltage applied between the substrates is reversed between the surface electrode 40 and the back electrode 46, and when the voltage is applied with the surface electrode 40 as the positive electrode and the back electrode 46 as the negative electrode, FIG. As shown in B), the particle group 34 moves to the display substrate 20 side and reaches the display substrate 20 side, and black display by the particle group 34 is performed.

  Thus, in the display device 10 according to the present embodiment, display is performed by the particle group 34 reaching the display substrate 20 or the back substrate 22 and adhering thereto. At this time, the surface of the display substrate 20 and the back substrate 22 facing each other is charged with a polarity different from the charged polarity of the particle group 34 (charge treatment is performed), so that the particle group 34 is attached to the substrate. Even when the voltage application is stopped (when a non-electric field is applied), an electrostatic force acts between the particle group 34 and the substrate, and the repulsion between the particles of the particle group 34 and the generation of a counter electric field due to the ion attraction of particles. However, the adhesion state of the particle group 34 to the substrate is stabilized.

  In particular, if the opposite surface of the display substrate 20 is charged with a polarity different from the charging polarity of the particle group 34, the adhesion state of the particle group 34 to the substrate is maintained even after the voltage application is stopped (when no electric field is applied). Since it is stabilized, the display image is stabilized.

  On the other hand, if the opposite surface of the back substrate is charged with a polarity different from the charging polarity of the particle group 34, the adhesion state of the particle group 34 to the substrate is maintained even after the voltage application is stopped (when no electric field is applied). Therefore, the movement of the particles of the particle group 34 to the display substrate 20 is suppressed.

Here, since the opposite surface of the display substrate 20 and the back substrate 22 is charged, as described above, the particle group 34 that has moved between the substrates by forming an electric field between the substrates is displayed on the display substrate. Particles that have been attached to the 20 side or the back substrate 22 side and are stably held, but have moved to either the display substrate 20 side or the back substrate 22 side due to this opposing surface being charged. When an electric field for moving the group 34 to the other substrate side is formed between the substrates, if the particle group 34 is held on the display substrate 20 side or the back substrate 22 side, image quality deterioration may occur. Is concerned.
However, in the display medium 12 of the present embodiment, as described above, the processing layer 21 and the processing layer 23 are provided on the display substrate 20 and the back substrate, respectively. 23, the particles attached to each of the display substrate 20 and the back substrate 22 do not stay on the attached substrate side, but easily move to the opposite substrate side according to the electric field formed between the substrates. Move to.
Therefore, even when the movement of the particle group 34 to the display substrate 20 side and the back substrate 22 side is repeatedly performed by forming an electric field between the display substrate 20 and the back substrate 22, It is considered that the particle group 34 can be moved according to the electric field formed between the substrates, and image quality deterioration can be suppressed.

  Therefore, according to the display medium 12 and the display device 10 of the present embodiment, since the processing layer 21 and the processing layer 23 are provided on the display substrate 20 and the back substrate 22, respectively, the display substrate 20 side or the back substrate 22 is provided. When the electric field that moves the particle group 34 that has reached the side toward the opposite surface is formed between the substrates, the particle group 34 can be easily moved toward the opposite surface. For this reason, image quality deterioration can be suppressed.

  Further, since the processing layer 21 and the processing layer 23 are provided after the charging process is performed on the opposing surfaces of the display substrate 20 and the back substrate 22, the display substrate 20 side or the back surface is formed by electrophoresis by the charging process on the opposing surface. The particle group 34 that has reached the substrate 22 side can be held on the side that has arrived, and excellent image quality retention can also be obtained.

  In the present embodiment, the form in which the charging process is performed on both the display substrate 20 and the back substrate 22 has been described. However, a form in which any one of the charging processes is performed may be used. In the present embodiment, the form in which only one surface (the display substrate 20 side) of the display medium is provided with the display function has been described. However, the present invention is not limited to this. These substrates may be constituted by display substrates (both substrates having translucency).

(Second Embodiment)
In the first embodiment, the form using only one type of particle group 34 has been described. However, in the present embodiment, a form in which two or more types of particle groups are applied will be described. Two or more kinds of particle groups are all charged with the same polarity.

As shown in FIG. 3, the display device 11 according to the present embodiment includes a display medium 13, a voltage application unit 16 that applies a voltage to the display medium 13, and a control unit 18.
Since the display device 11 has substantially the same configuration as the display device 10 described in the first embodiment, the same reference numerals are given to the same configuration, and detailed description thereof is omitted.

The display medium 13 includes a display substrate 20 that serves as an image display surface, a rear substrate 22 that faces the display substrate 20 with a gap, and holds these substrates at a predetermined interval, and between the substrates of the display substrate 20 and the rear substrate 22. The gap member 24 is configured to include a plurality of cells, a particle group 34 enclosed in each cell, and a large-diameter colored particle group 36 having optical reflection characteristics different from those of the particle group 34.
The opposing surfaces of the display substrate 20 and the back substrate 22 are charged in the same manner as in the first embodiment, and the processing layer 21 and the processing layer 23 are provided on the opposing surfaces.

  In the present embodiment, a plurality of types of particle groups 34 having different colors are dispersed in the dispersion medium 50 as the particle group 34.

In the present embodiment, as the three types of particle groups 34, the yellow color yellow particle group 34Y, the magenta magenta particle group 34M, and the cyan color cyan particle group 34C are dispersed as the particle groups 34 having different colors. However, it is not limited to three types.
The plurality of types of particle groups 34 are particle groups that perform electrophoresis between substrates, and the absolute value of the voltage required to move in accordance with the electric field is different for each color particle group. That is, each color particle group 34 (yellow particle group 34Y, magenta particle group 34M, and cyan particle group 34C) has a voltage range necessary for moving the color particle group 34 for each color. Are different.

  Examples of the particles of the plurality of types of particle groups 34 having different absolute values of voltages necessary to move in accordance with the electric field include the materials included in the particle group 34 described in the first embodiment. For example, by changing the amount of the charge control agent and magnetic powder, the type and concentration of the resin constituting the particles, etc., each particle dispersion containing particles with different charge amounts is prepared and mixed. It is done.

  Here, as described above, the yellow particle group 34Y, the magenta particle group 34M, and the cyan particle group 34C having different colors are dispersed as the three types of particle groups 34 in the display medium 12 of the present embodiment. These plural kinds of particle groups 34 have different absolute values of voltages necessary for moving in accordance with the electric field in the respective color particle groups.

  In the present embodiment, the absolute value of the voltage when each of the three color particle groups of the magenta magenta particle group 34M, the cyan cyan particle group 34C, and the yellow yellow particle group 34Y starts moving. Assuming that the magenta magenta particle group 34M is | Vtm |, the cyan cyan particle group 34C is | Vtc |, and the yellow yellow particle group 34Y is | Vty |. Also, the absolute value of the maximum voltage for moving almost all of the three color particle groups of the magenta particle group 34M, the cyan cyan particle group 34C, and the yellow yellow particle group 34Y of each color particle group 34. Assuming that the magenta magenta particle group 34M is | Vdm |, the cyan cyan particle group 34C is | Vdc |, and the yellow yellow particle group 34Y is | Vdy |.

  Note that the absolute values of Vtc, -Vtc, Vdc, -Vdc, Vtm, -Vtm, Vdm, -Vdm, Vty, -Vty, Vdy, and -Vdy described below are | Vtc | <| Vdc | <| Description will be made assuming that the relationship is Vtm | <| Vdm | <| Vty | <| Vdy |.

  Specifically, as shown in FIG. 4, for example, the three types of particle groups 34 are all dispersed in the dispersion medium 50 in a state of being charged with the same polarity, and are necessary for moving the cyan particle groups 34C. Absolute value of voltage range | Vtc ≦ Vc ≦ Vdc | (absolute value of a value between Vtc and Vdc), absolute value of voltage range necessary for moving magenta particle group 34M | Vtm ≦ Vm ≦ Vdm | (Vtm The absolute value of the value between Vty and Vdm), and the absolute value of the voltage range necessary to move the yellow particle group 34Y | Vty ≦ Vy ≦ Vdy | (the absolute value of the value between Vty and Vdy) It is set to be large without overlapping in order.

  Further, in order to independently drive the particle groups 34 of the respective colors, the absolute value | Vdc | of the maximum voltage for moving almost all the cyan particle groups 34C is the absolute value of the voltage range necessary for moving the magenta particle group 34M. Value | Vtm ≦ Vm ≦ Vdm | (the absolute value of the value between Vtm and Vdm) and the absolute value of the voltage range necessary to move the yellow particle group 34Y | Vty ≦ Vy ≦ Vdy | (Vty to Vdy The absolute value of the value between) is set smaller. In addition, the absolute value | Vdm | of the maximum voltage for moving almost all of the magenta particle group 34M is the absolute value of the voltage range necessary for moving the yellow particle group 34Y | Vty ≦ Vy ≦ Vdy | (from Vty to Vdy). Is set to be smaller than the absolute value).

  That is, in this embodiment, the voltage groups necessary for moving the color particle groups 34 are set so as not to overlap, so that the particle groups 34 for each color are independently driven.

The “voltage range necessary for moving the particle group 34” means the voltage necessary for the particle to start moving and the change in display density even if the voltage and voltage application time are further increased from the start of movement. It shows the voltage range until it disappears and the display density is saturated.
The “maximum voltage required to move almost all the particle groups 34” means that even if the voltage and the voltage application time are further increased from the start of the movement, the display density does not change and the display density is saturated. Indicates voltage.
Further, “almost all” means that there is a variation in the characteristics of the particle groups 34 of the respective colors, so that some of the characteristics of the particle groups 34 are different to the extent that they do not contribute to the display characteristics. That is, even if the voltage and the voltage application time are further increased from the start of the movement described above, the display density does not change and the display density is saturated.
“Display density” is the color density on the display surface side measured with the optical density (Optical Density = 0D) reflection densitometer X-rite's reflection densitometer. Apply a voltage and gradually change this voltage in the direction of increasing the measured concentration (increase or decrease the applied voltage) to saturate the concentration change per unit voltage, and in that state, adjust the voltage and voltage application time. Even when the density is increased, the density does not change, and the density is shown when the density is saturated.

  In the display medium 12 according to the present embodiment, the voltage applied between the substrates is gradually increased by applying a voltage from 0 V between the display substrate 20 and the back substrate 22 to increase the voltage value of the applied voltage. When the value exceeds + Vtc, the display density starts to change due to the movement of the cyan particle group 34C in the display medium 12. Further, when the voltage value is increased and the voltage applied between the substrates becomes + Vdc, the change in display density due to the movement of the cyan particle group 34C in the display medium 12 stops.

  When the voltage value is further increased and the voltage applied between the display substrate 20 and the back substrate 22 exceeds + Vtm, a change in display density due to the movement of the magenta particle group 34M starts to appear in the display medium 12. When the voltage value is further increased and the voltage applied between the display substrate 20 and the back substrate 22 becomes + Vdm, the change in display density due to the movement of the magenta particle group 34M in the display medium 12 stops.

  Further, when the voltage value is increased and the voltage applied between the substrates exceeds + Vty, a change in display density due to the movement of the yellow particle group 34Y starts to appear in the display medium 12. When the voltage value is further increased and the voltage applied between the substrates becomes + Vdy, the change in display density due to the movement of the yellow particle group 34Y in the display medium 12 stops.

  On the other hand, if the negative voltage from 0V is applied between the display substrate 20 and the back substrate 22 to gradually increase the absolute value of the voltage and the absolute value of the voltage −Vtc applied between the substrates is exceeded. In the display medium 12, the display density starts to change due to the movement of the cyan particle group 34C between the substrates. Furthermore, when the absolute value of the voltage value is increased and the voltage applied between the display substrate 20 and the rear substrate 22 becomes −Vdc or more, the change in display density due to the movement of the cyan particle group 34C in the display medium 12 occurs. Stop.

  When the negative voltage is further applied by increasing the absolute value of the voltage value, and the voltage applied between the display substrate 20 and the rear substrate 22 exceeds the absolute value of −Vtm, the magenta particles are displayed on the display medium 12. A change in display density due to movement of the group 34M begins to appear. When the absolute value of the voltage value is further increased and the voltage applied between the display substrate 20 and the back substrate 22 becomes −Vdm, the change in display density due to the movement of the magenta particle group 34M in the display medium 12 stops. .

  When the absolute value of the voltage value is further increased to apply a negative voltage, and the voltage applied between the display substrate 20 and the back substrate 22 exceeds the absolute value of −Vty, yellow particles are displayed on the display medium 12. The display density starts to change due to the movement of the group 34Y. When the absolute value of the voltage value is further increased and the voltage applied between the substrates becomes −Vdy, the change in display density due to the movement of the yellow particle group 34Y in the display medium 12 stops.

  That is, in the present embodiment, as shown in FIG. 4, the voltage applied between the substrates is within the range of −Vtc to Vtc (voltage range | Vtc | or less), and the display substrate 20 and the back substrate When applied between the substrate 22 and the substrate 22, the movement of the particles 34 (cyan particle group 34 C, magenta particle group 34 M, and yellow particle group 34 Y) to such a degree that the display density of the display medium 12 changes. Is not occurring. When a voltage greater than the absolute value of the voltage + Vtc and the voltage −Vtc is applied between the substrates, the degree of change in the display density of the display medium 12 for the cyan particle group 34C among the three color particle groups 34 occurs. The display density starts to change for the first time, and when a voltage equal to or higher than the absolute value | Vdc | of the voltage −Vdc and the voltage Vdc is applied, the display density per unit voltage does not change.

  Further, when a voltage is applied between the display substrate 20 and the back substrate 22 so that the voltage applied between the substrates is within a range of −Vtm to Vtm (voltage range | Vtm | or less), It can be said that the movement of the particles of the magenta particle group 34M and the yellow particle group 34Y to the extent that the display density of the display medium 12 changes does not occur. When a voltage higher than the absolute value of the voltage + Vtm and the voltage −Vtm is applied between the substrates, the display density of the display medium 12 is changed for the magenta particle group 34M and the magenta particle group 34M of the yellow particle group 34Y. The display density per unit voltage starts to change to the extent that particles are generated, and when the voltage −Vdm and voltage Vdm absolute value | Vdm | or more are applied, the display density changes. Disappear.

  Further, when a voltage is applied between the display substrate 20 and the back substrate 22 so that the voltage applied between the substrates is within the range of −Vty to Vty (voltage range | Vty | or less), the display It can be said that the movement of the particles of the yellow particle group 34Y to the extent that the display density of the medium 12 changes does not occur. When a voltage higher than the absolute value of the voltage + Vty and the voltage −Vty is applied between the substrates, the yellow particle group 34Y starts to move and display a particle that causes a change in the display density of the display medium 12. When the density starts to change and a voltage equal to or higher than the absolute value | Vdy | of the voltage −Vdy and the voltage Vdy is applied, the display density does not change.

  Next, with reference to FIG. 5, the mechanism of particle movement when an image is displayed on the display medium 12 will be described.

  For example, the display medium 12 will be described assuming that the yellow particle group 34Y, the magenta particle group 34M, and the cyan particle group 34C described with reference to FIG.

  In the following, the voltage applied between the substrates that is larger than the absolute value of the voltage necessary for the particles constituting the yellow particle group 34Y to start moving and less than or equal to the maximum voltage of the yellow particle group 34Y is referred to as “large voltage”. The voltage applied between the substrates that is larger than the absolute value of the voltage necessary for the particles constituting the magenta particle group 34M to start moving and is equal to or less than the maximum voltage of the magenta particle group 34M is referred to as “medium voltage”. The voltage applied between the substrates that is larger than the absolute value of the voltage required for the particles constituting the cyan particle group 34C to start moving and below the maximum voltage of the cyan particle group 34C is referred to as a “small voltage”. To do.

  Further, when a higher voltage is applied between the substrates on the display substrate 20 side than the back substrate 22 side, the respective voltages are referred to as “+ large voltage”, “+ medium voltage”, and “+ small voltage”, respectively. . Further, when a higher voltage is applied to the back substrate 22 side than the display substrate 20 side, the respective voltages are referred to as “−large voltage”, “−medium voltage”, and “−small voltage”, respectively. I will explain.

  As shown in FIG. 5A, when all of the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y as all the particle groups are positioned on the back substrate 22 side in the initial state (white display). State), when a “+ high voltage” is applied between the display substrate 20 and the back substrate 22 from this initial state, all the particle groups include a magenta particle group 34M, a cyan particle group 34C, and a yellow particle group 34Y. Moves to the display substrate 20 side. In this state, even if the voltage application is canceled, each particle group does not move while adhering to the display substrate 20 side, and subtractive color mixing (magenta) by the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y. In this case, the black color is displayed by the subtractive color mixture of cyan and yellow. (See FIG. 5B).

  Next, when “−medium voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5B, the magenta particle group 34 </ b> M among the particle groups 34 of all colors and cyan The particle group 34 </ b> C moves to the back substrate 22 side. For this reason, since only the yellow particle group 34Y is attached to the display substrate 20 side, yellow display is performed (see FIG. 5C).

  Further, when “+ small voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5C, the magenta particle group 34M and the cyan particle group 34C moved to the back substrate 22 side. The cyan particle group 34C moves to the display substrate 20 side. For this reason, the yellow particle group 34Y and the cyan particle group 34C are attached to the display substrate 20 side, and green is displayed by subtractive color mixture of yellow and cyan (see FIG. 5D).

  5B, when a “−small voltage” is applied between the display substrate 20 and the back substrate 22, the cyan particle groups 34C of all the particle groups 34 move to the back substrate 22 side. To do. For this reason, since the yellow particle group 34Y and the magenta particle group 34M are attached to the display substrate 20 side, red display is performed by additive mixing of cyan and magenta (see FIG. 5I).

  On the other hand, when “+ medium voltage” is applied between the display substrate 20 and the back substrate 22 from the initial state shown in FIG. 5A, all the particle groups 34 (magenta particle group 34M, cyan particle group 34C) are applied. , And the yellow particle group 34Y), the magenta particle group 34M and the cyan particle group 34C move to the display substrate 20 side. For this reason, since the magenta particle group 34M and the cyan particle group 34C are attached to the display substrate 20 side, blue is displayed by the subtractive color mixing of magenta and cyan (see FIG. 5E).

When a “−small voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5E, the magenta particle group 34M and the cyan particle group 34C adhering to the display substrate 20 side. Among them, the cyan particle group 34C moves to the back substrate 22 side.
Therefore, only the magenta particle group 34M is attached to the display substrate 20 side, so that a magenta color is displayed (see FIG. 5F).

When a “−high voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5F, the magenta particle group 34M adhering to the display substrate 20 side is moved to the back substrate 22 side. Moving.
For this reason, since nothing is adhered to the display substrate 20 side, white as the color of the large-diameter colored particle group 36 is displayed (see FIG. 5G).

  When a “+ small voltage” is applied between the display substrate 20 and the back substrate 22 from the initial state shown in FIG. 5A, all the particle groups 34 (magenta particle group 34M, cyan particle group) are applied. 34C and the yellow particle group 34Y), the cyan particle group 34C moves to the display substrate 20 side. For this reason, the cyan particle group 34C adheres to the display substrate 20 side, so that a cyan color is displayed (see FIG. 5H).

Further, when a “−large voltage” is applied between the display substrate 20 and the back substrate 22 from the state shown in FIG. 5I, all the particle groups 34 are back as shown in FIG. Moving to the substrate 22 side, white display is performed.
Similarly, when a “−high voltage” is applied between the display substrate 20 and the back substrate 22 from the state shown in FIG. 5D, all the particle groups 34 are formed as shown in FIG. Moving to the back substrate 22 side, white display is performed.

  Thus, in the present embodiment, by applying a voltage according to each particle group 34 between the substrates, the desired particles are selectively moved according to the electric field due to the voltage, so that a color other than the desired color can be obtained. The particles can be prevented from moving in the dispersion medium 50, color mixing with colors other than the desired color is suppressed, and color display is performed while image quality deterioration of the display medium 12 is suppressed. In addition, if the absolute value of the voltage required for each particle group 34 to move according to the electric field is different from each other, even if the voltage ranges necessary for moving according to the electric field overlap with each other, clear color display is possible. However, when the voltage ranges are different from each other, color mixing is further suppressed and color display is realized.

  Further, by dispersing the three color particle groups 34 of cyan, magenta, and yellow in the dispersion medium 50, cyan, magenta, yellow, blue, red, green, and black can be displayed, and a large white color can be displayed. White color can be displayed by the diameter colored particle group 36, and a desired color display can be performed.

Here, when the charging characteristics of each color particle group 34 (yellow particle group 34Y, magenta particle group 34M, and cyan particle group 34C) dispersed in the dispersion medium 50 change with the passage of time from the production of the display medium 12, Even if the same voltage or voltage having the same polarity is applied to the display medium 12, it may be difficult to display a desired color on the display medium 12.
However, according to the display medium 12 and the display device 10 of the present embodiment, since the particle groups 34 in the display medium 12 are dispersed in the dispersion medium 50 described in the first embodiment, charging is performed. Changes in characteristics are suppressed. Therefore, a change in charging characteristics of the particle group 34 that moves in accordance with the electric field dispersed in the display medium 12 is suppressed, and deterioration in image quality of the display medium 12 can be suppressed.

  Further, in the display device 11 according to the present embodiment, as in the display device 10 described in the first embodiment, the particle group 34 reaches the display substrate 20 or the back substrate 22 and adheres to the display. Done. At this time, the surface of the display substrate 20 and the back substrate 22 facing each other is charged with a polarity different from the charged polarity of the particle group 34 (charge treatment is performed), so that the particle group 34 is attached to the substrate. Even when the voltage application is stopped (when a non-electric field is applied), an electrostatic force acts between the particle group 34 and the substrate, and the repulsion between the particles of the particle group 34 and the generation of a counter electric field due to the ion attraction of particles. However, the adhesion state of the particle group 34 to the substrate is stabilized.

In the display medium 12 according to the present embodiment, as described above, the processing layer 21 and the processing layer 23 are provided on the display substrate 20 and the back substrate, respectively. 23, the particles attached to each of the display substrate 20 and the back substrate 22 do not stay on the attached substrate side, but easily move to the opposite substrate side according to the electric field formed between the substrates. Move to.
Therefore, even when the movement of the particle group 34 to the display substrate 20 side and the back substrate 22 side is repeatedly performed by forming an electric field between the display substrate 20 and the back substrate 22, The particle group 34 can be moved according to the electric field formed between the substrates, and image quality deterioration can be suppressed.

  Therefore, according to the display medium 13 and the display device 11 of the present embodiment, since the opposite surfaces of the display substrate 20 and the back substrate 22 are charged, the display substrate 20 side or the back substrate 22 is subjected to electrophoresis. The particle group 34 that has reached the side can be held on the side that has reached, and excellent image quality retention can be obtained, and the processing layer 21 and the processing layer 23 are provided on the display substrate 20 and the back substrate 22 respectively. Therefore, when an electric field that moves the particle group 34 that has reached the display substrate 20 side or the back substrate 22 side to the opposite surface side is formed between the substrates, it can be easily moved to the opposite surface side. it can. For this reason, image quality deterioration can be suppressed.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. However, Examples 1-2 and Examples 5-8 are reference examples.

(Preparation of large colored particles)
-Preparation of dispersion AA-
The following components were mixed and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion AA.
<Composition>
・ Cyclohexyl methacrylate: 53 parts by weight ・ Titanium oxide 1 (white pigment) (primary particle size 0.3 μm, Type CR63: manufactured by Ishihara Sangyo Co., Ltd.): 45 parts by weight ・ Cyclohexane: 5 parts by weight

-Preparation of charcoal dispersion AB-
The following components were mixed, and finely pulverized with a ball mill in the same manner as above to prepare a charcoal dispersion AB.
<Composition>
・ Calcium carbonate: 40 parts by weight ・ Water: 60 parts by weight

-Preparation of mixture AC-
The following components were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed liquid AC.
<Composition>
・ 2% serogen: 4.3g
Charcoal cal dispersion AB: 8.5g
・ 20% saline: 50 g

  35 g of dispersion AA, 1 g of divinylbenzene, and polymerization initiator AIBN: 0.35 g were weighed and mixed well, and deaeration was performed for 10 minutes with an ultrasonic machine. This was added to the mixed solution AC and emulsified with an emulsifier. Next, this emulsified liquid was put into a bottle, put into a silicone bottle, used with an injection needle, sufficiently degassed under reduced pressure, and sealed with nitrogen gas. Next, it was reacted at 65 ° C. for 15 hours to prepare particles. After cooling, cyclohexane was removed from the dispersion with a freeze dryer at −35 ° C. and 0.1 Pa for 2 days. The obtained particle powder was dispersed in ion-exchanged water, calcium carbonate was decomposed with hydrochloric acid water, and filtered. Thereafter, it was washed with sufficient distilled water, and passed through a nylon sieve having openings of 20 μm and 25 μm to make the particle sizes uniform. This was dried to obtain a group of white particles having an average particle diameter of 20 μm. This was made into the large diameter colored particle group.

(Preparation of magenta particles)
-Preparation of dispersion BA-
The following components were mixed and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion BA.
<Composition>
-Cyclohexyl methacrylate: 53 parts by mass-Magenta pigment (Carmine 6B: manufactured by Dainichi Seika Co., Ltd.): 3 parts by mass-Charge control agent (COPY CHARGE PSY VP2038: manufactured by Clariant Japan): 2 parts by mass

-Preparation of charcoal dispersion BB-
The following components were mixed, and finely pulverized with a ball mill in the same manner as above to prepare a charcoal dispersion BB.
<Composition>
-Calcium carbonate: 40 parts by mass-Water: 60 parts by mass

-Preparation of liquid mixture BC-
The following components were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed solution BC.
<Composition>
-2% serogen aqueous solution: 4.3 g
Charcoal cal dispersion B: 8.5g
・ 20% saline: 50 g

35 g of the dispersion BA, 1 g of divinylbenzene, and polymerization initiator AIBN: 0.35 g were weighed and mixed thoroughly, and deaerated with an ultrasonic machine for 10 minutes. This was added to the mixed solution BC and emulsified with an emulsifier. Next, this emulsified liquid was put into a bottle, put into a silicone bottle, used with an injection needle, sufficiently degassed under reduced pressure, and sealed with nitrogen gas. Next, it was reacted at 60 ° C. for 10 hours to prepare particles. After cooling, cyclohexane was removed from the dispersion with a freeze dryer at −35 ° C. and 0.1 Pa for 2 days. The obtained particle powder was dispersed in ion-exchanged water, calcium carbonate was decomposed with hydrochloric acid water, and filtered. Thereafter, it was washed with sufficient distilled water and dried. 2 parts by weight of the obtained particles were added to 98 parts by weight of silicone oil together with 2 parts by weight of a nonionic surfactant polyoxyethylene alkyl ether, and stirred to disperse to prepare a magenta particle group dispersion. The volume average particle diameter of the magenta particle group was 1 μm.
The magenta particle group thus produced was negatively charged.

(Preparation of cyan particles)
-Preparation of dispersion CA-
The following components were mixed and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion CA.
<Composition>
Styrene monomer: 53 parts by mass Cyan pigment (cyanine blue 4933M: manufactured by Dainichi Seika Co., Ltd.): 3 parts by mass Charge control agent (SBT-5-0016: manufactured by Orient Kogyo Co., Ltd.): 2 parts by mass

-Preparation of charcoal cal dispersion CB-
The following components were mixed and finely pulverized with a ball mill in the same manner as above to prepare a charcoal dispersion CB.
<Composition>
-Calcium carbonate: 40 parts by mass-Water: 60 parts by mass

-Preparation of liquid mixture CC-
The following components were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed solution CC.
<Composition>
-2% serogen aqueous solution: 4.3 g
Charcoal cal dispersion B: 8.5g
・ 20% saline: 50 g

35 g of dispersion CA, 1 g of divinylbenzene, and polymerization initiator AIBN: 0.35 g were weighed and mixed thoroughly, and deaerated with an ultrasonic machine for 10 minutes. This was added to the mixed solution CC and emulsified with an emulsifier. Next, this emulsified liquid was put into a bottle, put into a silicone bottle, used with an injection needle, sufficiently degassed under reduced pressure, and sealed with nitrogen gas. Next, it was reacted at 60 ° C. for 10 hours to prepare particles. After cooling, cyclohexane was removed from the dispersion with a freeze dryer at −35 ° C. and 0.1 Pa for 2 days. The obtained particle powder was dispersed in ion-exchanged water, calcium carbonate was decomposed with hydrochloric acid water, and filtered. Thereafter, it was washed with sufficient distilled water and dried. 2 parts by weight of the obtained particles were added to 98 parts by weight of silicone oil together with 2 parts by weight of a nonionic surfactant polyoxyethylene alkyl ether, and stirred and dispersed to prepare a dispersion of cyan particles. The volume average particle diameter of the cyan particles was 1 μm.
The cyan particle group thus produced was positively charged.

Example 1
A display medium having the same configuration as that of the above embodiment was produced as follows (see FIG. 1).
An ITO film having a thickness of 50 nm was formed as an electrode on a supporting substrate made of glass having a thickness of 0.7 mm by a sputtering method. The electrode surface of the back substrate composed of this ITO / glass substrate is immersed for 15 minutes in a 2 wt% ethanol solution of n-octyltriethoxysilane, 0.01 wt% acetic acid, and 1 wt% distilled water, and rinsed with pure water. After that, drying was performed at 120 ° C. for 30 minutes. As a result, a treatment layer was formed on the back substrate.
When the rear substrate on which the treatment layer was formed was measured from the side on which the treatment layer was formed using an optical densitometer X-Rite MODEL404 (manufactured by X-Rite), the L * value was 93.
In the examples, the average value of the measurement results measured at any 10 points in the measurement target region using the optical densitometer was shown as the measurement result by the optical densitometer.

  Moreover, it was 50 nm when the thickness of the process layer was measured with the Dektak 6M level | step difference meter (made by Veeco).

  Then, after apply | coating the layer using the photosensitive polyimide varnish, the gap | interval member of height 100micrometer and width 20micrometer was formed by performing exposure and wet etching.

After forming a heat-fusible adhesive layer (not shown) on the upper part of the gap member, after filling the dispersion liquid of the above large-diameter colored particles (white particles) and the magenta particles, the same as the back substrate The display substrate (L * value: 93, thickness: 50 nm) made of ITO / glass manufactured as described above and having a treatment layer formed is opposed so that the surfaces (electrode surfaces) on which the treatment layers are formed face each other. The display medium was manufactured by applying heat to the back substrate.

  In this way, a display medium was produced. Using the produced display medium, a voltage of 40 V was applied to both electrodes so that the electrode of the display substrate was positive and the electrode of the back substrate was negative. As a result, the negatively charged magenta particles were observed to move to the display substrate by the electric field generated by the voltage application, and the display medium displayed a magenta color.

Thereafter, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, the negatively charged magenta particles were observed to move to the back substrate due to the electric field generated by voltage application, and the display medium displayed white.
After the above magenta color display and white display are alternately repeated 1000 times, a voltage of 40 V is applied to both electrodes so that the display substrate electrode is negative and the back substrate electrode is positive so that white display is performed. When applied, the display medium showed white.
In this state, the display substrate is peeled from the display medium, and the color density of the display substrate is measured in the same manner as described above with the optical densitometer X-Rite MODEL404 (manufactured by X-Rite) from the side where the treatment layer is formed. As a result, the L * value was 93.
For this reason, there is no change in color density before voltage application, and it can be said that no adhesion of magenta particle groups was observed.

(Example 2)
A display medium having the same configuration as that of the above embodiment was produced as follows (see FIG. 1).
In Example 1 described above, a treatment layer was provided on each of the display substrate and the back substrate, and in the treatment of providing this treatment layer on the display substrate and the back substrate, a 2 wt% ethanol solution of n-octyltriethoxysilane was used. In Example 2, a display medium was produced in the same manner as in Example 1 except that a 2 wt% ethanol solution of n-octadecyltriethoxysilane was used instead of the 2 wt% ethanol solution of n-octyltriethoxysilane. Together with the evaluation.

  In Example 2, when the optical density and thickness of the display substrate and the back substrate on which the treatment layer was formed were measured in the same manner as in Example 1, the L * value was 93 and the thickness was 60 nm.

  Further, in the same manner as in Example 1, for the display medium manufactured in Example 2, a voltage of 40 V was applied to both electrodes so that the electrode of the display substrate was positive and the electrode of the back substrate was negative. As a result, the negatively charged magenta particles were observed to move to the display substrate by the electric field generated by the voltage application, and the display medium displayed a magenta color.

  Thereafter, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, the negatively charged magenta particles were observed to move to the back substrate due to the electric field generated by voltage application, and the display medium displayed white.

After the magenta color display and the white display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed using the optical densitometer X-Rite MODEL404 ( When measured in the same manner as in Example 1, the L * value was 93.
For this reason, there is no change in color density before voltage application, and it can be said that no adhesion of magenta particle groups was observed.

(Example 3)
A display medium having the same configuration as that of the above embodiment was produced as follows (see FIG. 1).
In the first and second embodiments, the processing layer is provided directly on each of the display substrate and the back substrate. However, in this third embodiment, after the charging process is performed on each of the opposing surfaces of the display substrate and the back substrate, the embodiment is performed. A display medium was produced and evaluated in the same manner as in Example 2 except that a treatment layer was provided in the same manner as in Example 2.

Specifically, a display medium having the same configuration as that of the above embodiment was manufactured as follows (see FIG. 1).
An ITO film having a thickness of 50 nm was formed as an electrode on a supporting substrate made of glass having a thickness of 0.7 mm by a sputtering method. The electrode surface of the back substrate composed of this ITO / glass substrate was immersed in a 4 wt% aqueous solution of carboxyethylsilanetriol for 20 minutes, rinsed purely, and then dried at 120 ° C. for 30 minutes. Thereby, the electrode surface of the back substrate was negatively charged.

  Furthermore, this substrate was immersed in a 2 wt% ethanol solution of n-octadecyltriethoxysilane, 0.01 wt% acetic acid and 1 wt% distilled water for 15 minutes, rinsed with pure water, and then dried at 120 ° C. for 30 minutes. Went. As a result, electrode treatment was performed on the rear substrate, and a treatment layer was formed on the opposite surface subjected to the electrode treatment. In addition, a display substrate having the same configuration as that of the rear substrate was produced in the same manner as the rear substrate.

  When the optical density and thickness of the display substrate and the back substrate on which the treatment layer was formed after this charging treatment were measured in the same manner as in Example 1, the L * value was 93 and the thickness was 30 nm.

A display medium having the same configuration as that of the above embodiment was produced as follows (see FIG. 1).
By applying a layer using a photosensitive polyimide varnish to the surface provided with the treatment layer after the charging treatment of the back substrate prepared in Example 3 was performed, and then performing exposure and wet etching. A gap member having a height of 100 μm and a width of 20 μm was formed.

  After forming a heat-fusible adhesive layer (not shown) on the upper part of the gap member, the dispersion liquid of the large-diameter colored particle group (white particle group) and the cyan particle group was filled, and then Example 3 The display substrate manufactured in (1) was bonded to the rear substrate so that the surfaces (electrode surfaces) provided with the treatment layers were opposed to each other, and heat was applied to manufacture a display medium.

  Using this display medium, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, it was observed that the positively charged cyan particles were moved to the display substrate by the electric field generated by the voltage application, and the display medium displayed cyan.

  Thereafter, when the voltage application was turned off (stopped), the cyan particle group was held on the display substrate even after 24 hours, and the display color of the medium remained cyan and did not change.

  Further, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was positive and the back substrate electrode was negative. As a result, it was observed that the positively charged cyan particles were moved to the rear substrate by the electric field generated by the voltage application, and the display medium displayed white.

Further, after the cyan color display and the white color display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed by the optical densitometer X-Rite. When measured in the same manner as in Example 1 using MODEL404 (X-Rite), the L * value was 92.
For this reason, compared with before voltage application, there was almost no change in color density, and it can be said that the cyan particle group did not adhere to the display substrate.

Example 4
In the preparation of the treatment layer in the display medium preparation method in Example 3, in Example 3, 15% was added to a mixed solution of 2 wt% ethanol solution of n-octadecyltriethoxysilane, 0.01 wt% acetic acid, and 1 wt% distilled water. After dipping for 1 minute and rinsing with pure water, a treatment layer was formed by performing the treatment of drying at 120 ° C. for 30 minutes only once, but in Example 4, except that this treatment was repeated 6 times, All the same operations as in Example 3 were performed to produce a display medium.

  When the optical density and thickness of the display substrate and the back substrate of the display medium produced in Example 4 were measured in the same manner as in Example 1, the L * value was 93 and the thickness was 200 nm.

  Using the display medium produced in Example 4, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, it was observed that the positively charged cyan particles were moved to the display substrate by the electric field generated by the voltage application, and the display medium displayed cyan.

  Thereafter, when the voltage application was turned off (stopped), the cyan particle group was held on the display substrate even after 24 hours, and the display color of the medium remained cyan and did not change.

  Further, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was positive and the back substrate electrode was negative. As a result, it was observed that the positively charged cyan particles were moved to the rear substrate by the electric field generated by the voltage application, and the display medium displayed white.

Further, after the cyan color display and the white color display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed by the optical densitometer X-Rite. When measured in the same manner as in Example 1 using MODEL404 (X-Rite), the L * value was 93.
For this reason, it can be said that there was no change in the color density as compared to before voltage application, and no cyan particle group adhered to the display substrate.

(Example 5)
In Example 1 described above, a treatment layer was provided on each of the display substrate and the back substrate, and in the treatment of providing this treatment layer on the display substrate and the back substrate, a 2 wt% ethanol solution of n-octyltriethoxysilane was used. In Example 5, a display medium was produced in the same manner as in Example 1 except that a 2 wt% ethanol solution of n-dodecyltriethoxysilane was used instead of the 2 wt% ethanol solution of n-octyltriethoxysilane. Together with the evaluation.

For the display medium produced in Example 5, the optical density and thickness of the display substrate and the back substrate on which the treatment layer was formed were measured in the same manner as in Example 1. The L * value was 93 and the thickness was 50 nm.
Further, in the same manner as in Example 1, for the display medium manufactured in Example 5, a voltage of 40 V was applied to both electrodes so that the electrode of the display substrate was positive and the electrode of the back substrate was negative. As a result, the negatively charged magenta particles were observed to move to the display substrate by the electric field generated by the voltage application, and the display medium displayed a magenta color.

  Thereafter, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, the negatively charged magenta particles were observed to move to the back substrate due to the electric field generated by voltage application, and the display medium displayed white.

After the magenta color display and the white display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed using the optical densitometer X-Rite MODEL404 ( When measured in the same manner as in Example 1, the L * value was 93.
For this reason, there is no change in color density before voltage application, and it can be said that no adhesion of magenta particle groups was observed.

(Example 6)
In Example 1 described above, a treatment layer was provided on each of the display substrate and the back substrate, and in the treatment of providing this treatment layer on the display substrate and the back substrate, a 2 wt% ethanol solution of n-octyltriethoxysilane was used. In Example 6, a display medium was produced in the same manner as in Example 1 except that a 2 wt% ethanol solution of n-octadecyltrimethoxysilane was used instead of the 2 wt% ethanol solution of n-octyltriethoxysilane. Together with the evaluation.

For the display medium produced in Example 6, the optical density and thickness of the display substrate and the back substrate on which the treatment layer was formed were measured in the same manner as in Example 1. The L * value was 93 and the thickness was 50 nm.
In the same manner as in Example 1, for the display medium manufactured in Example 6, a voltage of 40 V was applied to both electrodes so that the electrode of the display substrate was positive and the electrode of the back substrate was negative. As a result, the negatively charged magenta particles were observed to move to the display substrate by the electric field generated by the voltage application, and the display medium displayed a magenta color.

  Thereafter, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, the negatively charged magenta particles were observed to move to the back substrate due to the electric field generated by voltage application, and the display medium displayed white.

After the magenta color display and the white display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed using the optical densitometer X-Rite MODEL404 ( When measured in the same manner as in Example 1, the L * value was 93.
For this reason, there is no change in color density before voltage application, and it can be said that no adhesion of magenta particle groups was observed.

(Example 7)
In Example 1 described above, a treatment layer was provided on each of the display substrate and the back substrate, and in the treatment of providing this treatment layer on the display substrate and the back substrate, a 2 wt% ethanol solution of n-octyltriethoxysilane was used. In Example 7, a display medium was produced in the same manner as in Example 1 except that a 2 wt% ethanol solution of n-hexadecyltriethoxysilane was used instead of the 2 wt% ethanol solution of n-octyltriethoxysilane. And evaluated.

For the display medium produced in Example 7, the optical density and thickness of the display substrate and the back substrate on which the treatment layer was formed were measured in the same manner as in Example 1. The L * value was 93 and the thickness was 50 nm.
In the same manner as in Example 1, for the display medium manufactured in Example 7, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was positive and the back substrate electrode was negative. As a result, the negatively charged magenta particles were observed to move to the display substrate by the electric field generated by the voltage application, and the display medium displayed a magenta color.

  Thereafter, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, the negatively charged magenta particles were observed to move to the back substrate due to the electric field generated by voltage application, and the display medium displayed white.

  After the magenta color display and the white display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed using the optical densitometer X-Rite MODEL404 ( When measured in the same manner as in Example 1, the L * value was 93.

  For this reason, there is no change in color density before voltage application, and it can be said that no adhesion of magenta particle groups was observed.

(Example 8)
In Example 1 described above, a treatment layer was provided on each of the display substrate and the back substrate, and in the treatment of providing this treatment layer on the display substrate and the back substrate, a 2 wt% ethanol solution of n-octyltriethoxysilane was used. Example 8 was the same as Example 1 except that a 2 wt% ethanol solution of N- (6-aminohexyl) aminopropyltrimethoxysilane was used instead of the 2 wt% ethanol solution of n-octyltriethoxysilane. A display medium was prepared and evaluated.

In the display medium produced in Example 8, the optical density and thickness of the display substrate and the back substrate on which the treatment layer was formed were measured in the same manner as in Example 1. As a result, the L * value was 93 and the thickness was 50 nm.
In the same manner as in Example 1, for the display medium manufactured in Example 8, a voltage of 40 V was applied to both electrodes so that the electrode on the display substrate was positive and the electrode on the back substrate was negative. As a result, the negatively charged magenta particles were observed to move to the display substrate by the electric field generated by the voltage application, and the display medium displayed a magenta color.

  Thereafter, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, the negatively charged magenta particles were observed to move to the back substrate due to the electric field generated by voltage application, and the display medium displayed white.

After the magenta color display and the white display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed using the optical densitometer X-Rite MODEL404 ( When measured in the same manner as in Example 1, the L * value was 93.
For this reason, there is no change in color density before voltage application, and it can be said that no adhesion of magenta particle groups was observed.

Example 9
In the production of the treatment layer in the method for producing a display medium in Example 3 above, in Example 3, a 2 wt% ethanol solution of n-octadecyltriethoxysilane was used, but in Example 9, n-octadecyltriethoxy was used. A display medium was prepared in the same manner as in Example 3 except that a 6 wt% ethanol solution of silane was used.
When the optical density and thickness of the display substrate and the back substrate of the display medium produced in Example 9 were measured in the same manner as in Example 1, the L * value was 93 and the thickness was 100 nm.

Using the display medium produced in this Example 9, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, it was observed that the positively charged cyan particles were moved to the display substrate by the electric field generated by the voltage application, and the display medium displayed cyan.
Thereafter, when the voltage application was turned off (stopped), the cyan particle group was held on the display substrate even after 24 hours, and the display color of the medium remained cyan and did not change.

Further, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was positive and the back substrate electrode was negative. As a result, it was observed that the positively charged cyan particles were moved to the rear substrate by the electric field generated by the voltage application, and the display medium displayed white.
Further, after the cyan color display and the white color display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed by the optical densitometer X-Rite. When measured in the same manner as in Example 1 using MODEL404 (X-Rite), the L * value was 93.
For this reason, it can be said that there was no change in the color density as compared to before voltage application, and no cyan particle group adhered to the display substrate.

(Example 10)
In the production of the treatment layer in the method for producing the display medium in Example 3, in Example 3, a 2 wt% ethanol solution of n-octadecyltriethoxysilane was used. In Example 10, n-octadecyltriethoxy was used. A display medium was produced in the same manner as in Example 3 except that a 15 wt% ethanol solution of silane was used.

  When the optical density and thickness of the display substrate and the back substrate of the display medium produced in Example 10 were measured in the same manner as in Example 1, the L * value was 93 and the thickness was 150 nm.

Using the display medium manufactured in Example 10, a voltage of 40 V was applied to both electrodes so that the electrode of the display substrate was negative and the electrode of the back substrate was positive. As a result, it was observed that the positively charged cyan particles were moved to the display substrate by the electric field generated by the voltage application, and the display medium displayed cyan.
Thereafter, when the voltage application was turned off (stopped), the cyan particle group was held on the display substrate even after 24 hours, and the display color of the medium remained cyan and did not change.
Further, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was positive and the back substrate electrode was negative. As a result, it was observed that the positively charged cyan particles were moved to the rear substrate by the electric field generated by the voltage application, and the display medium displayed white.

Further, after the cyan color display and the white color display were alternately repeated 1000 times, the display substrate was peeled off from the display medium, and the color density of the display substrate was measured from the side on which the treatment layer was formed by the optical densitometer X-Rite. When measured in the same manner as in Example 1 using MODEL404 (X-Rite), the L * value was 93.
For this reason, it can be said that there was no change in the color density as compared to before voltage application, and no cyan particle group adhered to the display substrate.

(Comparative Example 1)
A display medium was produced in the same manner as in Example 1 except that no treatment layer was provided on the electrode surfaces of the display substrate and the back substrate.

  Using the produced display medium, a voltage of 40 V was applied to both electrodes so that the electrode of the display substrate was positive and the electrode of the back substrate was negative. As a result, the negatively charged magenta particles were observed to move to the display substrate by the electric field generated by the voltage application, and the display medium displayed a magenta color.

  Thereafter, a voltage of 40 V was applied to both electrodes so that the display substrate electrode was negative and the back substrate electrode was positive. As a result, the negatively charged magenta particles were observed to move to the back substrate by the electric field generated by the voltage application, and the display medium displayed white.

In this state, the display substrate is peeled from the display medium, and the color density of the display substrate is measured in the same manner as described above with the optical densitometer X-Rite MODEL404 (manufactured by X-Rite) from the side where the treatment layer is formed. As a result, the L * value was 82.
For this reason, a change was seen in the color density before voltage application, and it is estimated that the magenta particle group was attached.

Further, for the display medium produced in Comparative Example 1, the display substrate electrode is negative and the back substrate electrode is used so that white display is performed after the magenta color display and the white display are alternately repeated 1000 times. When a voltage of 40 V was applied to both electrodes so as to be positive, the display medium showed white.
In this state, the display substrate is peeled from the display medium, and the color density of the display substrate is measured in the same manner as described above with the optical densitometer X-Rite MODEL404 (manufactured by X-Rite) from the side where the treatment layer is formed. As a result, the L * value was 79.
For this reason, a change was seen in the color density before voltage application, and it is estimated that the magenta particle group was attached.

1 is a schematic configuration diagram of a display medium and a display device according to an embodiment. It is explanatory drawing which shows typically the movement aspect of a particle group when a voltage is applied between the substrate of the display medium which concerns on embodiment, and the display medium of a display apparatus. It is a schematic block diagram of the display medium and display apparatus which concern on 2nd Embodiment. It is a diagram which shows typically the relationship between the voltage to apply and the moving amount (display density | concentration) of particle | grains. It is explanatory drawing which shows typically the relationship between the voltage aspect applied between the board | substrates of a display medium, and the movement aspect of particle | grains.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 11 Display apparatus 12, 13 Display medium 16 Voltage application part 18 Control part 20 Display substrate 21, 23 Processing layer 22 Back surface substrate 34M Magenta particle group 34Y Yellow particle group 34C Cyan particle group 34 Particle group 40 Surface electrode 46 Rear electrode 50 Dispersion medium

Claims (8)

A pair of substrates having electrodes, at least one of which is translucent and disposed with a gap;
A dispersion medium sealed between the pair of substrates;
A group of particles dispersed in the dispersion medium and moving in the dispersion medium in response to an electric field formed between the pair of substrates;
Provided on at least one of the opposing surfaces of the pair of substrates, and formed by treating at least one of the opposing surfaces of the pair of substrates with a treating agent containing a silane coupling agent represented by the following general formula (1). Processing layer,
A charged layer provided on at least one of the pair of substrates and charged with a charging polarity different from that of the particle group;
A display medium comprising:
Formula (1) R ¹ —Si (OR ² ) ₃
(In the general formula (1), R ¹ represents a monovalent aliphatic hydrocarbon group having 7 or more carbon atoms, and R ² represents a monovalent aliphatic hydrocarbon group having 4 or less carbon atoms.) The display medium according to claim 1 , wherein the charging layer is provided between at least one of the pair of substrates and the processing layer. The display medium according to claim 1, wherein the pair of substrates is a display substrate and a back substrate, and the processing layer is provided at least on the facing surface on the display substrate side. The display medium according to claim 3 , wherein the charging layer is provided at least between a processing layer provided on an opposing surface on the display substrate side and the display substrate. Display medium as claimed in any one of claims 1 to 4, wherein the thickness of the treated layer is in the range of 10nm or more 200nm or less. A pair of substrates having electrodes, at least one of which is translucent and disposed with a gap, a dispersion medium sealed between the pair of substrates, and dispersed in the dispersion medium, A particle group that moves in the dispersion medium in response to an electric field formed between the pair of substrates and at least one of the opposing surfaces of the pair of substrates, and at least one of the opposing surfaces of the pair of substrates is Provided on at least one of the treatment layer formed by treatment with the treatment agent containing the silane coupling agent represented by the general formula (1) and the pair of substrates, and is charged with a charge polarity different from that of the particle group. A display medium having a charged layer ;
Voltage applying means for applying a voltage between the pair of substrates;
A display device comprising:
Formula (1) R ¹ —Si (OR ² ) ₃
(In the general formula (1), R ¹ represents a monovalent aliphatic hydrocarbon group having 7 or more carbon atoms, and R ² represents a monovalent aliphatic hydrocarbon group having 4 or less carbon atoms.) 7. The particle group according to claim 6 , wherein the particle group includes a plurality of kinds of particles colored in different colors while having different absolute values of voltages necessary for moving according to an electric field. Display device. The display device according to claim 7 , wherein the plurality of types of particles have a voltage range necessary for moving according to an electric field for each type, and the voltage ranges are different from each other.