JP2004054248A - Electrophoretic display device and method for manufacturing electrophoretic display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display device which prevents the leakage etc., of liquid and a method for manufacturing the same. <P>SOLUTION: The electrophoretic display device performs display by dispersing charged particles 4 into the liquid 3 and moving the charged particles 4 by applying an electric field thereto. The device has a first substrate 1a which has electrodes 5a and 5b, a film 2 which is attached to the first substrate 1a and forms a hermetic section between itself and the surface of the first substrate 1a, and the liquid 3 into which the charged particles 4 are dispersed. The hermetic section is formed by the substrate 1a and the film 2 and since the liquid 3 and the charged particles 4 are sealed in the hermetic section, the leakage of the liquid crystal 3 from the hermetic section can be effectively prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to an electrophoretic display device that performs display using electrophoresis of charged particles, and a method of manufacturing the electrophoretic display device.
[0002]
[Prior art]
2. Description of the Related Art An electrophoretic display device that performs display using an electrophoretic phenomenon of charged particles is known. This apparatus arranges an insulating liquid and charged particles between a pair of substrates at least one of which is transparent, and changes the distribution of the charged particles by applying an electric field by providing an electrode on one or both of the substrates. , Thereby performing display. This electrophoretic display device
・ Unlike liquid crystal display devices, there is no polarization characteristic and viewing angle dependency,
・ Since the polarizing plate is not used, the light utilization is high and bright,
-Because it is not a light-emitting type such as CRT, LED or EL, it is a natural display and eyes are not easily fatigued when viewed for a long time,
・ The display can be rewritten with low power, and it has memory properties, so it consumes almost no power except when rewriting the display.
There are advantages such as.
[0003]
By the way, in such an electrophoretic display device, it is necessary to prevent leakage of the insulating liquid.
[0004]
In addition, when a spacer is arranged to make the substrate gap uniform or a partition member is arranged to prevent display unevenness so as to prevent the movement of charged particles from pixel to pixel, the optical aperture ratio is reduced. And the contrast and brightness of the display deteriorate. Further, if stable contact between the substrate and the partition member is not sufficiently ensured, there remains a problem that unevenness of the thickness of the insulating liquid and nonuniformity of the charged particle concentration with time cannot be prevented.
[0005]
Therefore, for example, Patent Literature 1 discloses a device in which an insulating liquid or charged particles are sealed in a microcapsule, and the microcapsule is sandwiched between a pair of substrates.
[0006]
In addition, for example, Patent Document 2 proposes supplying microcapsules one by one from a nozzle to a substrate surface using an inkjet technique as a means for arranging the microcapsules at a desired position as described above.
[0007]
Further, for example, Patent Document 3 proposes a method in which an insulating liquid is discharged to a region surrounded by a partition member on a substrate surface by an inkjet method, and then a counter substrate is attached. According to this method, different types of insulating liquids can be supplied to predetermined positions and separated, and a multicolor display device can be manufactured.
[0008]
[Patent Document 1]
Japanese Patent No. 2551783
[Patent Document 2]
JP-A-2000-35598
[Patent Document 3]
JP 2001-235771 A
[0009]
[Problems to be solved by the invention]
These prior arts have the advantage of preventing leakage of the insulating liquid, but have the problem that it is difficult to accurately arrange the microcapsules at positions corresponding to the display electrodes.
[0010]
In addition, it is technically very difficult to reliably supply microcapsules one by one by an ink jet means. In addition, a large number of microcapsules need to be arranged at a predetermined position in a large high definition display panel, and the method of supplying microcapsules one by one from a nozzle has a problem that it takes time to produce a display panel.
[0011]
Further, conventionally, there has been a problem that air bubbles are mixed in or the charged particles move to another pixel when the opposing substrate is attached.
[0012]
Accordingly, the present invention provides an electrophoretic display device that prevents liquid leakage and the like, and a method for manufacturing the same.
[0013]
[Means for Solving the Problems]
The present invention has been made in view of the above circumstances, an electrophoretic display device that performs display based on dispersing charged particles in a liquid, moving the charged particles by applying an electric field,
A first substrate having electrodes,
A coating attached to the first substrate and forming a sealed portion between the first substrate and a surface of the first substrate;
And a liquid in which the charged particles are dispersed, which is disposed in the closed portion.
[0014]
Further, the present invention is a method of manufacturing an electrophoretic display device that performs display based on dispersing charged particles in a liquid and moving the charged particles by applying an electric field,
Forming a region having a high affinity for the liquid and a region having a low affinity on the substrate surface,
Forming a droplet of liquid in which the charged particles are dispersed in the high affinity region,
Forming a coating on a surface of the droplet that does not contact the substrate.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0016]
(1) First, the overall structure of the electrophoretic display device according to the present invention will be described.
[0017]
The electrophoretic display device according to the present invention, as illustrated in FIG. 1, forms a sealed portion between a first substrate 1a and the first substrate 1a so as to be attached along the first substrate 1a. A coating 2, a liquid 3 and a plurality of charged particles 4 disposed in the closed portion, and a pair of electrodes 5 a and 5 b disposed in the vicinity of the closed portion are provided. Display is performed based on moving the charged particles 4 by applying a voltage to the electrodes 5a and 5b.
[0018]
As shown in FIG. 2, the second substrate 1b may be arranged with a predetermined gap in the first substrate 1a, and the sealing portion may be sandwiched between these substrates 1a and 1b. When the second substrate 1b is arranged as described above, the coating 2 can be protected.
[0019]
FIG. 2 illustrates a state in which the coating 2 is deformed by pressing the second substrate 1b. By pressing the second substrate 1b in this manner, the top of the coating 2 is flattened and the gap between the coating 1 and the substrate 1b is eliminated. And the thickness of the liquid 3 is equalized. These usually have good results on the characteristics of the display panel. That is, when the second substrate 1b is arranged as shown in FIG. 2, the thickness of the liquid 3 is made substantially uniform, and the display quality can be improved.
[0020]
In addition, a plurality of the above-described coatings 2 may be provided to form a plurality of sealed portions, but it is not necessary that all of the coatings 2 be attached to the first substrate 1a, and some of the coatings 2 are formed on the second substrate 1b. It may be attached to the side.
[0021]
Further, a color filter may be arranged near the closed portion to perform color display.
[0022]
When the second substrate 1b is arranged as described above, a spacer (not shown) is arranged between the first substrate 1a and the second substrate 1b so that the substrate gap is kept constant and uniform. It is good to do so.
[0023]
(2) Hereinafter, each member will be described in detail.
[0024]
(2-1) Substrate
The above-described substrates 1a and 1b form a closed portion together with the coating 2, hold the liquid 3, and play a role of mechanically holding the entire shape of the electrophoretic display device.
[0025]
The substrates 1a and 1b (accurately, the surface shapes of the substrates) do not necessarily have to be flat, but may be curved depending on the application. In addition, a flexible electrophoretic display device can be obtained by using a bendable flexible material for the substrate.
[0026]
The preferred range of the thickness of the substrates 1a and 1b depends on the size of the electrophoretic display device (display panel), the strength of the substrate material and the state of use, and is about 25 μm to 500 μm in the case of a flexible and small panel, and in the case of a large panel. Is suitably in the range of about 100 μm to about 2 mm. The thickness of the substrate is selected depending on the design of the display panel and the strength in practical use, and is not directly related as a component of the present invention.
[0027]
The substrates 1a and 1b are made of ceramics such as glass, alumina and quartz, metals such as aluminum, titanium and stainless steel, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), and polyimide (PI). And a material such as plastic such as polyetherimide (PEI) and polycarbonate (PC). When it is difficult to secure mechanical strength, solvent resistance, and the like with a single material, a composite material can be used. For example, it can be formed into a sheet by adding a filler of metal or ceramic to plastic to form a reinforced plastic substrate. In addition, a substrate with improved liquid permeability by coating the surface of a lightweight substrate made of porous ceramics with a plastic material, a substrate with an improved solvent resistance by coating a ceramic material on the surface of a plastic film with poor solvent resistance, etc. Is also available.
[0028]
At least one of the substrates 1a and 1b is made transparent so that the liquid 3 can be observed from the outside. Further, a surface hardened layer and an antireflection layer are preferably formed on the transparent substrate.
[0029]
The substrate 1a shown in FIG. 1 is a concept including the electrodes 5a and 5b and an insulating layer disposed between the electrodes. In other words, the substrate in this embodiment mode may be a substrate formed by laminating electrodes and insulating layers, or a substrate formed of only the above-described plastic material (without laminating electrodes and insulating layers). It is a concept that includes.
[0030]
(2-2) Coating
On the other hand, the above-mentioned coating 2 forms a sealed portion together with the substrate, and plays a role of holding the liquid 3 and the charged particles 4.
[0031]
Examples of the material of the coating 2 include a liquid-impermeable (liquid-impermeable) polymer material, and specifically, a polyamide resin, a polyurethane resin, a polyester resin, a polyurea resin, a polymelamine resin, Either an epoxy resin or a phenol resin, or a mixed resin thereof can be used. These materials need to be insoluble in the liquid 3.
[0032]
Incidentally, when the second substrate 1b is not used as shown in FIG. 1, the coating 2 is required to have not only liquid impermeability and insolubility but also strength and flatness, but as shown in FIG. When the two substrates 1b are used, since the strength and flatness can be ensured by the second substrates 1b, the coating 2 only needs to satisfy liquid impermeability and insolubility.
[0033]
The lower limit of the thickness of the coating 2 is limited by its mechanical strength, and is about 0.1 μm depending on the film material. There is no essential restriction on the upper limit of the thickness, and a thickness of up to about 100 μm is appropriate as a design choice.
[0034]
For forming such a film, a method of forming a film on an interface by a physical or chemical method, which has been conventionally used as a method for preparing microcapsules, can be used. However, in the preparation of the microcapsules, a film is formed on the entire surface of the core material contained in the capsule, but in the present invention, a film is formed on a part of the droplets arranged on the substrate 1a (or 1b). The droplets are made up by the substrate and the coating.
[0035]
Examples of the film forming method include an in-situ method, an interfacial polymerization method, and a liquid surface casting method.
[0036]
Examples of the material of the formed film include urea resin, urea-formaldehyde resin, melamine-formaldehyde resin, polyurethane, polyurea-polyurethane, polyamide, polyester, polysulfonamide, polycarbonate, polysulfinate, polyepoxy, and polyacrylate. , Polymethacrylate, polyvinyl acetate, gelatin and the like.
[0037]
Further, an example of a method for forming the coating 2 will be specifically described. In the in-situ method, a polymer monomer or a prepolymer is supplied to a substrate 1a (or 1b) on which droplets are arranged to form a polymer on the surface of the droplets. In the interfacial polymerization method, a part of the raw material of the film-forming polymer is contained in the droplet in advance, and then the second raw material of the film-forming polymer is supplied to the droplet to form the surface of the droplet. To form a polymer. In the liquid surface casting method, a film material is dissolved in an appropriate solvent, and the solution is supplied to a substrate on which droplets are arranged to deposit the film material on the surface of the droplets.
[0038]
Preparation of the coating 2 by the in-situ method can be performed as follows. First, a droplet composed of a predetermined amount of the charged particles 4 and the liquid 3 is applied to a predetermined position on an insulating substrate on which a predetermined electrode is patterned. The particles 4 and the liquid 3 may be applied to the substrate at the same time, or the particles 4 and then the liquid 3 or the liquid 3 and then the particles 4 may be applied separately. Printing means such as an ink jet printing method and an electrostatic printing method can be cited as the means for giving, but the present invention is not limited thereto. It is also possible to use a method in which a material having poor liquid wetting is applied in a pattern on the surface of the substrate, and the liquid 3 is selectively applied only to a portion having no pattern by bringing the liquid 3 into contact with this surface. Next, a liquid containing a film-forming material is brought into contact with the substrate to form a film at the interface with the liquid 3 on the substrate. The liquid containing the film-forming material must be in contact with the liquid 3 without causing miscibility to form an interface. Since the liquid 3 described below is hardly miscible with water, an aqueous solution of the film-forming material can be used as the liquid containing the film-forming material. For example, in order to form a film containing a urea resin as a component, a predetermined temperature may be maintained by using an aqueous solution containing urea, formaldehyde as a film forming material, and ethylene-maleic anhydride resin as a urea resin forming catalyst. A coating made of a resorcinol resin, a phenol resin, a polyurethane resin, or the like can be similarly prepared.
[0039]
Preparation of the coating 2 by the interfacial polymerization method can be performed as follows. In the same manner as described above, a droplet composed of a predetermined amount of a charged particle 4, a liquid 3, and a first film forming material, which will be described later, is applied to a predetermined position on an insulating substrate having a predetermined electrode patterned on the surface. Next, the liquid containing the second film-forming material is brought into contact with the above-mentioned substrate to form a film on the interface with the liquid 3 on the substrate. The first film forming material and the second film forming material come into contact with each other to form a film. The first film-forming material is oil-soluble, and examples thereof include substances having a plurality of sites that undergo a condensation reaction with a compound having active hydrogen, such as polyisocyanates and polycarboxylic acid halides. The second film-forming material is a substance that reacts with the first film-forming material to form a film, and examples thereof include compounds having a plurality of active hydrogens such as polyhydric alcohols and polyamines. A polyurethane resin, a polyurea resin, a polyester resin, a polyamide resin, or the like is formed as a film on the surface of the liquid 3 by a combination of the first and second film forming materials.
[0040]
By the way, as shown by reference numeral 6 in FIG. 3A, the coating 2 may be covered with a surface protective layer. Suitable materials for the surface protection layer 6 include acrylic resin, epoxy resin, and the like, which have strength or liquid impermeability or transparency equivalent to or higher than that of the coating film 2. When the hardness of the device surface is required, an inorganic coating layer such as ceramics or a resin layer containing inorganic particles may be deposited as the outermost surface layer to form a hardened surface layer. Further, an antireflection effect may be provided to reduce the reflection on the panel surface by refractive index matching with air or to form an optical interference structure to make the display easier to see.
[0041]
The surface protective layer may have a flat surface (upper surface in the figure) as indicated by reference numeral 16 in FIG. Thereby, there is an advantage that the risk of damage to the surface protective layer is reduced, and dirt is easily wiped off. Such a surface protective layer can be formed using a commercially available resin having good leveling properties.
[0042]
(2-3) Liquid
As the liquid 3, a liquid capable of dispersing the charged particles 4 may be used. Specifically, cyclohexane, heptane, decane, kerosene, decalin, aliphatic hydrocarbons such as isoparaffin hydrocarbons, toluene, xylene, Aromatic hydrocarbons such as ethylbenzene, cumene, cymene, diamylbenzene, tetralin, and solvent naphtha, 2-ethylhexyl chloride, trichloroethane, ethylene chloride, tetrachloroethylene, dichlorobenzene, trifluorotrifluoroethane, tetrachloroethane Halogenated hydrocarbons such as carbon chloride and ethane tetrafluoride difluoride, alcohols such as 2-propanol, butanol, 3-pentanol, 3-heptanol, 2-methylcyclohexanol and benzyl alcohol, butyl ether, hexyl ether, Anisole, cresyl methyl e Ketones such as 2-butanone, 2-methyl-4-pentanone, 3-heptanone, 2,6-dimethyl-4-heptanone, cyclohexanone, amyl formate, propyl acetate, isoamyl acetate, acetic acid Esters of 2-ethylhexyl, isoamyl propionate, diethyl oxalate, diethyl malonate, benzyl acetate, methyl benzoate, ethyl benzoate, oleic acid, silicone oil, olive oil, coconut oil, castor oil, liquid paraffin, etc. Oils or any mixture thereof may be used.
[0043]
If necessary, a charge control agent, a particle dispersant, a specific gravity adjuster, a colorant, a viscosity adjuster, and the like may be added to the liquid 3.
[0044]
Among them, the charge control agent and the particle dispersant are added for the purpose of stably dispersing the charged particles 4 in the liquid 3. The charge control agent has the effect of preventing particles from aggregating due to electrostatic repulsion between the particles by charging the particles, and the particle dispersant adsorbs on the particle surface to eliminate direct contact between the particles, thereby reducing the It has the effect of preventing aggregation.
[0045]
Examples of charge control agents include cobalt naphthenate, manganese naphthenate, zirconium octylate, cobalt stearate, fatty acid salts such as cobalt ethylenediaminetetraacetate, calcium nonylphenylsulfonate, sodium dioctylsulfonate, calcium dioctylsulfonate, bis (2-ethylhexyl) sodium sulfosuccinate and the like, sulfonates or sulfates such as copper dodecyl sulfate and nickel dodecyl sulfate, phosphate compounds such as zinc phosphate, dipalmitoyl phosphatidylcholine, dipalmitoyl phosphatidylserine, and hexadecyltrimethylammonium Amine compounds such as bromide and dioctadecyldimethylammonium chloride; alkylene succinimides such as polyaminopolybutenyl succinimide , Rosin-modified maleic acid resin, ethylene - such as fatty acid compound resins such as maleic anhydride copolymer and the like.
[0046]
Examples of the particle dispersant include polymers such as paraffin wax, ethylene oxide-propylene oxide copolymer, and polyoxyethylene nonylphenyl ether.
[0047]
Better results are often obtained when the charge control agent and the particle dispersant are used in combination, but only one of them may be used. Depending on the constituent materials of the liquid 3 and the charged particles 4 described below, the particles 4 may maintain an appropriate charge in the liquid 3 without particularly adding a charge control agent.
[0048]
(2-4) Charged particles
The charged particles 4 are charged particles and are capable of electrophoresis in the liquid 3 under the influence of an electric field.
[0049]
As the charged particles 4,
Particles of insoluble coloring material,
・ Insoluble particles colored with a coloring material,
· Surface-treated to stabilize their dispersion
Any of these may be used.
[0050]
Examples of the insoluble coloring material that can be used for the charged particles 4 include C.I. I. Black pigments such as C.I. Pigment Black 1, 7 and molybdenum sulfide; I. Pigment White 6, 18, white pigments such as C.I. I. Red pigments such as C.I. Pigment Red 122, 123, 149, 168, 177, 178; I. Green pigments such as C.I. Pigment Green 7, 18, 36; I. Blue pigments such as CI Pigment Blue 15, 27, 28 and 60; I. Yellow pigments such as CI Pigment Yellow 53, 95, 97 and 110; I. Red-violet pigments such as C.I. Pigment Violet 16, 19, and 23; I. Pigment Blue 2, 16, C.I. I. And particles of a blue-green pigment such as CI Pigment Green 4.
[0051]
As a coloring material for coloring the insoluble particles, a dye can be used in addition to the pigments described above. Examples of the carrier particles (that is, insoluble particles) include inorganic material particles such as glass, hollow glass, silica, magnesia, alumina, and zeolite; and polymers having a residue of a nonpolar monomer such as polyethylene, polypropylene, and polystyrene. Particles, polar polymer particles having residues of polar monomers such as polyacryl, polymethacryl, polyester, polyamide resin, etc., acidic monomers such as acrylic acid, methacrylic acid, maleic acid, styrene sulfonic acid or Acid type polymer particles having a residue of a salt thereof, dimethylaminoethyl methacrylate, allylamine, ethyleneimine, basic polymer particles having a residue of a salt thereof such as a basic monomer such as vinylpyridine, or Copolymer particles between these polymers. The polymer particles may be internally crosslinked or mixed with an inorganic filler for the purpose of improving dimensional stability, abrasion resistance, solvent resistance and the like.
[0052]
As the colorant held by the colorant carrier particles, the pigments described above can be used, and a dye that can be adsorbed or included in the colorant carrier can also be used.
[0053]
Examples of the dye include C.I. I. Direct Black 17, C.I. I. Direct Yellow 44, C.I. I. Direct Red 23, 79, C.I. I. Direct Blue 15, 86, C.I. I. Direct Green 59 and the like can be used for the inorganic material particles. C.I. I. Solvent Orange 5, 45, C.I. I. Solvent Blue 25, C.I. I. Basic Yellow 28, C.I. I. Basic Red 14, 18, C.I. I. Basic Violet 7, C.I. I. Basic Blue 3, C.I. I. Acid Black 52, C.I. I. Acid Yellow 38, C.I. I. Acid Red 18, C.I. I. Acid violet 49, C.I. I. Acid blue 83, 113, C.I. I. Acid Green 25, C.I. I. Reactive Black 5, C.I. I. Reactive Yellow 2, C.I. I. Reactive Red 3, 43, C.I. I. Reactive Blue 2, 5, 19 and the like can be used for coloring the polymer particles.
[0054]
Further, by coating the pigment particles (charged particles formed of an insoluble coloring material),
・ Particles whose dispersibility in liquid and charging characteristics are adjusted,
Particles that prevent the colorant from migrating from the particles 4 to the liquid 3
Can be produced, but these particles can also be suitably used in the present invention. Materials that can be used for the coating are polyethylene, polypropylene, polymers having a residue of a non-polar monomer such as polystyrene, polyacryl, polymethacryl, polyester, and a polar monomer such as a polyamide resin. Polar polymers having a residue, acrylic acid, methacrylic acid, maleic acid, acid type polymers having a residue of an acidic monomer such as styrene sulfonic acid or a salt thereof, dimethylaminoethyl methacrylate, allylamine, Examples include basic polymers having a residue of a basic monomer such as ethyleneimine or vinylpyridine or a salt thereof, or copolymers between these polymers. These polymers are appropriately selected and used depending on the type of the liquid in which the particles are dispersed.
[0055]
The pigment particles (charged particles formed of an insoluble coloring material) or the particles obtained by coating the pigment particles may be treated with a surface modifier such as an alkylsilane treatment agent, a fluorinated alkylsilane treatment agent, or an alkyltitanium treatment agent. Can be used as the particles of the coloring material.
[0056]
(2-5) Electrode
Although the electrodes 5a and 5b are arranged along one substrate 1a in FIG. 1, in the case of the electrophoretic display device shown in FIG. 2, the electrodes 5a and 5b are arranged (so as to sandwich the liquid 3) between the substrates 1a and 1b. You may.
[0057]
(2-6) Next, the color arrangement of the charged particles 4 and the electrodes 5a and 5b will be described.
[0058]
Now, if one electrode 5a is made to have the opposite polarity to the charged particles 4 and the other electrode 5b is made to have the same polarity as the charged particles 4, the charged particles 4 are located near the electrode 5a as shown in FIG. I will move. When one electrode 5a has the same polarity as the charged particles 4 and the other electrode 5b has the opposite polarity to the charged particles 4, the charged particles 4 move so as to cover the electrode 5b as shown in FIG. I do.
[0059]
Here, assuming that the color of the charged particles 4 is black and a white colored layer 9b is arranged so as to cover the electrode 5b, in the case of FIG. In the case of FIG. 4B, black display is performed based on the visual recognition of the charged particles 4. By controlling the magnitude of the voltage applied to the electrodes and the application time, an intermediate state between FIGS. 4A and 4B can be obtained, so that gray multi-tone display is also possible. .
[0060]
When a chromatic layer is used as the colored layer 9b, chromatic display is performed in the case of FIG. 4A, and black display is performed in the case of FIG. 4B. If a plurality of display elements having different colors of the colored layer 9b are arranged in a set to form one pixel, a multi-color display pixel can be formed. If red, green, blue or cyan, magenta, and yellow are selected as the colored layer 9b in the plurality of display elements constituting the pixel, a mixed color display pixel using three primary colors is obtained. By arranging a large number of the color display pixels on a surface, a color display panel is obtained.
[0061]
It is also possible to configure a display element using white particles as the charged particles 4. When a black-and-white display element is formed using white particles, the colored layer 9b may be black.
[0062]
When chromatic particles are used as the charged particles 4 and a white / black or gray achromatic layer is used as the colored layer 9b, it is possible to provide a pixel displaying a chromatic color having a different tone.
[0063]
In any case, by using a layer having a color similar to that of the charged particles 4 as the coloring layer 9a, the apparent display contrast of the pixel can be improved.
[0064]
Note that the colored layer 9a may be disposed so as to cover the electrode 5a. It is sufficient that these colored layers 9a and 9b are arranged so as to cover the electrodes 5a and 5b, and the colored layer 9a and the electrode 5a (or the colored layer 9b and the electrode 5b) are in contact with each other but not in contact with each other. Is also good.
[0065]
If the apparent color of the substrate surface is different from the color of the charged particles 4, the color change can be observed by changing the distribution of the charged particles 4, so that the formation of the colored layers 9a and 9b is not essential. If a metal electrode is used as the electrode 5b and a substrate covered with a transparent insulating layer is used, it can be used as a display element for controlling the reflected light on the metal surface by the distribution of the charged particles 4. If a transparent electrode is used as the electrode 5b and a transparent substrate covered with a transparent insulating layer is used, it can be used as a display element that controls transmitted light by the distribution of the charged particles 4.
[0066]
When a plurality of closed portions are provided, the colors of the colored layer 9b and the charged particles 4 may be changed for each closed portion.
[0067]
(2-7) Next, the arrangement of the coating 2, the electrode shape, and the like will be described.
[0068]
By the way, in FIG. 1 and FIG. 2, two coatings 2 (that is, pixels) are arranged, but it is not limited to this, and three or more coatings may be arranged. In that case, the coatings 2 may be arranged in one row or in a plurality of rows (that is, two-dimensionally).
[0069]
FIGS. 5A and 5B are diagrams showing an example in which four coatings 2 are arranged in two rows. FIG. 5A shows a six-fold symmetry and FIG. 5B shows a four-fold symmetry. This is an example in which pixels are arranged. In the case of the pixel arrangement shown in FIG. 2B, the electrophoretic display device can control display by matrix driving of XY orthogonal coordinates. 1A, the cross-sectional view taken along the line AB corresponds to FIG.
[0070]
The electrodes 5a shown in FIGS. 5A and 5B are annular, but are not limited to this. If the electrode 5a is formed in a polygonal shape such as a hexagon or a quadrangle, an area invalid for display between adjacent pixels is narrowed, and an improvement in display contrast can be expected.
[0071]
Since FIG. 5 shows an example of an annular electrode, the coating 2 formed on this substrate is shown as a shield (a part of a spherical shell is cut out in a plane), but the shape of the coating 2 is a shield. It is not limited to the shape. As long as it does not overlap with an adjacent pixel, it may have an arbitrary shape including a polygon in the substrate surface direction. When a polygonal electrode such as a hexagon or a quadrangle is used as described above, it is a preferable example to use a hexagonal or a quadrangle or the like polygonal film 2 in the substrate surface direction.
[0072]
In FIG. 5, the electrode 5b is commonly connected to two adjacent pixels, but in this case, the display of the two adjacent pixels can be separately controlled by controlling the voltage applied to the electrode 5a. Of course, the electrodes may be individually drawn for each pixel and driven, or the electrodes may be commonly connected between adjacent pixels.
[0073]
(3) Manufacturing method of electrophoretic display device
6 and 7 show an example of a manufacturing process of the electrophoresis apparatus of the present invention. The method for manufacturing an electrophoretic display device according to the present invention includes:
Forming a region having a high affinity for the liquid 3 and a region having a low affinity on the surface of the first substrate 1a;
A step of forming a droplet of the liquid 3 in which the charged particles 4 are dispersed in a region having a high affinity, and a step of forming the coating 2 on a surface of the droplet that does not contact the substrate
Consists of
[0074]
FIG. 6A shows a state in which a layer of a material having a high affinity is formed on the surface of the substrate 1a. FIG. 6 (b) is a pattern in which a material having a low affinity is patterned thereon. As a result, as shown in FIG. 6 (b), a region having a high affinity (a layer of a material having a high affinity is formed) (Exposed portion) and a region with low affinity.
[0075]
As described below, the high affinity region is provided with the liquid 3 and the coating film 2 formed thereon to form a sealed portion serving as a pixel. Therefore, the periphery is surrounded by a low affinity region for each pixel. It is preferred that
[0076]
The liquid 3 is placed on this substrate. As will be described later, there are various methods of arranging the liquid 3. In any case, the liquid 3 spreads over the surface in the high affinity region and is uniformly wetted, but is repelled when it comes to the low affinity region. The spread stops there. As a result, as shown in FIG. 6C, the liquid 3 forms a droplet only in a region having a high affinity. A liquid 11 containing a film-forming material is disposed thereon (FIG. 7A), and a film 2 is formed on the interface (FIG. 7B).
[0077]
(3-1) Hereinafter, a method of arranging the liquid 3 and the charged particles 4 will be described.
[0078]
A “region having a high affinity for liquid 3” and a “region having a low affinity” are previously formed on the substrate surface, and the liquid 3 and the charged particles 4 are arranged in the “region having a high affinity”. It is good to
[0079]
Here, as a method of forming a “region having a high affinity with the liquid 3” and a “region having a low affinity” on the surface of the substrate, a substrate having a material having a high affinity with the liquid 3 is used. It is preferable that a layer having a low affinity is partially formed on the substrate surface. Such “low affinity layer”
・ Even if it is formed by partially disposing a material (affinity control material) different from the substrate,
-It may be formed by modifying a part of the substrate (or the insulating layer 8 formed on the substrate) by a physical or chemical method.
[0080]
6A, the acrylic resin 8 was formed on the surface of the substrate 1a in the step shown in FIG. 6A, and the polymer layer 10 containing water was formed in the step shown in FIG. 6B. As a result, in the stage of FIG. 6B, the region where the acrylic resin, which is a region having a high affinity for the liquid 3, was exposed, and the region of the water-containing polymer, which was a region having a low affinity for the liquid 3, was the outermost surface Is formed.
[0081]
As the affinity control material, for example, a material having a particularly low surface energy such as a fluororesin such as tetrafluoroethylene, a polyalcohol such as polyvinyl alcohol and polyhydroxyethyl methacrylate, polyacrylamide, poly N-methylacrylamide, etc. And polycarboxylic acids such as acrylamides, polyacrylic acid and polymethacrylic acid or salts thereof, and hydrophilic polymers mainly containing polysaccharides such as gum arabic and carboxymethylcellulose. These may be formed into a pattern by a normal printing process, or may be directly subjected to photo-patterning using the above-mentioned material having photocrosslinking property or photosolubility.
[0082]
Physical and scientific methods for reforming include contacting a liquid containing an oxidizing agent such as a fluorosilane treatment agent, hydrogen peroxide, peracetate, perborate, percarbonate, or ozone. Or the like, or a method of oxidizing the surface layer of a treatment site by contacting with an oxidizing gas such as the above or by applying ultraviolet rays under an appropriate atmosphere. Separately, a method of contacting an acid or alkali solution to hydrolyze or solvolyze the surface layer of the treatment site, or a combination treatment of an electron beam, an ultraviolet ray, an oxidizing agent, a radical generator with a polymerizable precursor or a reactive oligomer A method of forming a hydrophilic resin at the treatment site by the method described above is also effective.
[0083]
When a hydrophilic pattern is formed as a layer having a low affinity, the affinity may be further reduced by adding water to the hydrophilic pattern.
[0084]
Here, the affinity of the pattern for the liquid can be evaluated by the contact angle of the liquid on the pattern surface. In the present invention, the expression "the affinity is low" means that the contact angle is at least 10 degrees or more. If the contact angle is smaller than this, it is difficult to arrange liquid droplets of a size large enough to perform a display operation on the substrate independently for each pixel.
[0085]
As a method of forming a “region having a high affinity for liquid 3” and a “region having a low affinity for liquid 3” on the surface of the substrate, a substrate made of “material having low affinity for liquid 3” is used. It is preferable to form a layer having high properties partially on the substrate surface. Such a “high affinity layer”
-Even if it is formed by partially disposing a material (hydrophobic material) different from the substrate (see reference numeral 10 in FIG. 6B),
Even if it is formed by modifying a part of the substrate (or the insulating layer 8 formed on the substrate) by a physical or chemical method,
good.
[0086]
Examples of the above-mentioned hydrophobic material include a hydrophobic resin which is a polystyrene, a polyacrylester, a polyalkene or a mixture thereof.
[0087]
Next, the liquid 3 and the charged particles 4 are dropped into the “high affinity region” (see FIG. 6C). The arrangement of the liquid 3 and the charged particles 4 on the surface of the first substrate 1a is preferably performed using a nozzle. The liquid 3 and the charged particles 4 may be dropped in a state where the charged particles 4 are dispersed in the liquid 3 or may be dropped separately. As the dropping method, a usual liquid coating method such as dipping, brush coating, spin coating, spray coating, and ink jet coating may be used. When the charged particles 4 are arranged at a timing different from that of the liquid 3, it is preferable that the charged particles 4 be dropped after being mixed with an appropriate vehicle. Further, the coating may be performed by a powder coating process such as electrostatic coating without using such a vehicle.
[0088]
If the amount of the liquid applied to the substrate is too large, the liquid pool spreads to the hydrophilic portion. Therefore, the amount of liquid to be applied should be such that the liquid pool does not spread beyond the hydrophilic pattern portion. The adjustment of the applied amount of the liquid may be performed by applying only a predetermined sufficient amount in the step of applying the liquid to the substrate, or may be performed by a step of removing an excess amount of the liquid after applying the sufficient amount or more.
[0089]
In the droplet forming step, two or more types of liquids may be supplied.
[0090]
(3-2) Hereinafter, an arrangement method of the electrodes 5a and 5b will be described.
[0091]
The electrodes 5a and 5b may be formed by a known method such as a screen printing process or a combination of photoresist and etching.
[0092]
(3-3) Hereinafter, a method of arranging the coating 2 will be described.
[0093]
Next, the coating 2 is formed on the surface of the liquid 3. The formation method is,
A method of applying a film material to the surface of the liquid 3,
A method of producing a membrane material on said surface (by reaction of the raw materials);
Can be mentioned. As the former method (that is, a method of applying the film material to the surface of the liquid 3), a method of melting the film material or dissolving the film material in a solvent to form a liquid and forming fine liquid droplets and applying the liquid to the surface of the liquid 3. Can be mentioned. When the film material is dissolved with a solvent, the solvent dissolves in the liquid or evaporates into the air, and only the film material is extracted.
[0094]
Examples of coatable film materials include polystyrene, acrylonitrile / styrene resin, polyvinyl formal, polyvinyl acetal, acrylic resin, and vinyl polymers such as polyvinyl acetate.
[0095]
In the step of forming the film material on the surface, a polymer material that can be a film material, that is, a polymer monomer or a reactive oligomer is supplied to generate a polymer on the surface of the pool. To form a coating.
[0096]
Raw materials for the polymer include polyamines such as urea, melamine, ethylenediamine, and diethylenetetramine, or phenols such as resorcinol and a combination of phenols and formaldehyde, tetramethylenediamine, hexamethylenediamine, and metaxylylenediamine. Polyethylenes such as polyethyleneimine and polyallylamine, and polyalcohols such as ethylene glycol, 1,4-butanediol, glycerin, pentaerythritol, and polyvinyl alcohol, and succinate chloride, adipic chloride, sebacic chloride, Polybasic acid halides such as terephthalic acid chloride and isophthalic acid chloride, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, Takenate D-110N, Takeney D-160 N, Takenate D-170N (Takenate product names of Takeda Chemical Industries) and polyisocyanates such as poly-haloformates such combinations may be employed with polyepoxides.
[0097]
The chemical formation of the polymer film will be described in more detail. In order to form a polymer film from a combination of polyamines or phenols and formaldehyde, the above-mentioned polyamines or phenols or a mixture of polyamines and phenols is mixed in the presence of an acid-type polymer. The aqueous solution is brought into contact with a substrate having on its surface a puddle to be coated with a film, and formaldehyde is present in the solution and heated.
[0098]
The acid-type polymer is adsorbed on the interface between the liquid pool, which is an organic liquid, and the aqueous solution, and acts as a catalyst for the condensation reaction between formaldehyde and polyamines or phenols due to its acidity. Promotes the molecular formation reaction.
[0099]
Examples of the acid type polymer that can be used for the above purpose include poly (styrene-styrenesulfonic acid), poly (ethylene-maleic anhydride) and the like.
[0100]
Further, in order to form a polymer film from a combination of polyamines, polyalcohols, polybasic acid halides, polyisocyanates, polyhaloformates, polyepoxides, polybasic acid halides, Any of isocyanates, polyhaloformates, polyepoxides, or a mixture of two or more thereof is contained in the above-mentioned liquid pool, and any of polyamines, polyalcohols, or a mixture thereof is added thereto. A polymer forming reaction is caused on the surface of the liquid pool by contacting the aqueous solution of the liquid.
[0101]
In the case where polybasic acid halides are used, a base may be contained in an aqueous solution of the above-mentioned polyamines and polyalcohols for the purpose of neutralizing and removing hydrogen halide that is replicated in the polymer formation reaction.
[0102]
After the film 2 is formed, it is preferable to remove a residue at the time of film formation by an appropriate washing operation, if necessary.
[0103]
If a surface protective layer is required, a coating of a two-component reactive curable resin, an ultraviolet curable resin, or an inorganic material may be applied (see FIG. 3).
[0104]
Further, a second substrate 1b as shown in FIG. 2 may be arranged.
[0105]
Next, effects of the present embodiment will be described.
[0106]
According to the present embodiment, leakage of the liquid 3 and the charged particles 4 can be prevented by the coating 2.
[0107]
Further, according to the present embodiment, a spacer for uniformizing the gap between the substrates and a partition member for preventing the movement of charged particles from pixel to pixel are not required. Therefore, there is no concern about a decrease in the optical aperture ratio due to the arrangement of these spacers and partition members.
[0108]
Furthermore, since microcapsules as in Conventional Examples 1 and 2 are not used, manufacturing is simplified.
[0109]
Further, when a “region having a high affinity for the liquid 3” and a “region having a low affinity” are formed on the substrate surface by the above-described method, the positions of the electrodes 5a and 5b and the position of the liquid 3 are determined. Can be matched exactly.
[0110]
In addition, when the coating 2 is formed by the above-described method, the incorporation of bubbles into the liquid 3 can be reduced.
[0111]
Hereinafter, the present invention will be described in more detail by way of examples.
[0112]
(Example 1)
In this example, a display panel (electrophoretic display device) having the structure shown in FIG. 1 was manufactured by the method shown in FIGS.
[0113]
That is, a 0.2 mm-thick polyester substrate coated with an acrylic resin having a thickness of about 1 μm was used as the substrate A, and a 400-nm-thick aluminum film was formed on the surface thereof. The aluminum film was coated with a photoresist and patterned, and unnecessary aluminum was removed by etching to form a display electrode 5b having a width of 100 μm. Then, it was coated to a thickness of about 3 μm with a thermosetting acrylic resin in which alumina fine particles were dispersed, and this was used as a white insulating layer (see reference numeral 7). Next, 400 μm of titanium and 1 μm of a photosensitive acrylic resin in which a black carbon pigment was dispersed were deposited and patterned to form a collector electrode 5 a covered with a 12 μm-wide black layer. Further, the entire surface was covered with a thermosetting transparent acrylic resin 8.
[0114]
Next, a photosensitive liquid (a liquid composed of 2 parts by weight of ammonium bichromate, 6 parts by weight of casein, 100 parts by weight of water, and 1 part by weight of 28% aqueous ammonia) is applied to the surface of the acrylic resin 8, dried, and exposed and patterned. And washed to form hydrophilic regions. In order to further enhance the hydrophilicity, a 20% aqueous solution of gum arabic was applied and left for a while.
[0115]
Next, crushed poly (acryl-styrene) particles (4 parts by weight) containing a black pigment were dispersed as charged particles in a liquid containing 50 parts by weight of Isopar H (manufactured by Exxon) and 0.05 parts by weight of zirconium octylate. Then, 2 parts by weight of sebacic chloride was further added to prepare a liquid (particle dispersion liquid).
[0116]
A small amount of water was applied to the surface of the substrate, left for about 5 seconds, and then the particle dispersion liquid was applied to form a droplet at a portion surrounded by the hydrophilic region (FIG. 6C). reference).
[0117]
Thereafter, the substrate was gently brought into contact with an aqueous solution 11 consisting of 10 parts by weight of polyallylamine, 3 parts by weight of ethylene glycol, 1 part by weight of sodium carbonate, and 60 parts by weight of water at room temperature (see FIG. 7A). At the stage when the coating 2 was formed, the mixture was heated to 45 ° C. for 30 minutes to complete the reaction (FIG. 7B). By washing with cold water, an electrophoretic display device was completed.
[0118]
Now, when a DC voltage of 40 V is applied to the electrodes 5a and 5b, the charged particles 4 move toward the positive electrode (that is, the charged particles 4 are negatively charged). Then, by changing the polarity of the applied voltage, the charged particles 4 were moved as shown in FIG. 4A or 4B, and it was found that monochrome display was possible. After 8 hours, voltage application was attempted again, and a similar display operation was confirmed.
[0119]
(Example 2)
Instead of the casein chromate sensitizer used in Example 1, a hydrophilic region was formed using polyvinyl chromate. An electrophoretic display device was able to be manufactured by following the same procedures as in Example 1 except for the above.
[0120]
(Example 3)
An electrophoretic display was prepared in the same manner as in Example 1, except that an aqueous solution comprising 1 part by weight of ammonium dichromate, 3 parts by weight of PVA (polymerization degree 500) and 50 parts by weight of water was used as a photosensitive agent.
[0121]
50 parts by weight of Isopar H (manufactured by Exxon) and 0.05 part by weight of zirconium octylate were dispersed as charged particles with crushed poly (acryl-styrene) particles (4 parts by weight) containing a black pigment, and 5 parts by weight of hexamethylene diisocyanate trimer (Takenate D-170HN, manufactured by Takeda Pharmaceutical Company Limited) was added.
[0122]
A small amount of water was applied to the surface of the substrate, left for about 5 seconds, and then the liquid (insulating liquid in which particles 4 were dispersed) was dropped. As a result, the droplet was disposed at a portion surrounded by the hydrophilic region 10 (see FIG. 6C).
[0123]
The above substrate was gently brought into contact with a solution prepared by dissolving 8 parts by weight of acetoacetyl group-modified partially saponified polyvinyl alcohol (Gosefimer Z-210, manufactured by Nippon Synthetic Chemical Industry) in 92 parts by weight of water saturated with Isopar H. (See FIG. 7A).
[0124]
The film formation reaction was completed by heating to 80 ° C. for 8 hours (see FIG. 7B). Then, it was washed with cold water.
[0125]
Although a voltage was applied in the same manner as in Example 1, a black-and-white display operation could be confirmed.
[0126]
(Example 4)
A room temperature-curable transparent epoxy resin was applied on the display panel prepared in the same manner as in Example 1, and a 50 μm polyester film was laminated thereon to form a surface protective layer. When a 1 Hz write signal was applied to the display panel and the display inversion operation was continued, the display panel operated normally even after 24 hours.
[0127]
(Comparative Example 1)
The process was performed up to the stage shown in FIG. 6C in the same manner as in Example 1, and display driving was performed in the same manner as in Example 1 for a display panel on which no film was formed. The insulating liquid 3 gradually evaporated, and the black and white display operation could not be performed due to drying within 20 minutes.
[0128]
(Comparative Example 2)
A display panel, which is made in the same manner as in Comparative Example 1 and has a display operation, is covered with a 50 μm polyester film via a 50 μm outer frame type spacer, and the end portion is sealed with a room temperature curing epoxy resin to protect the surface. It was created.
[0129]
In this display panel, droplets of the display medium in contact with the polyester film were moved along the film, and independent droplets could not be maintained, resulting in significant display unevenness.
[0130]
【The invention's effect】
As described above, according to the present invention, leakage of the insulating liquid and the charged particles can be prevented by the coating.
[0131]
Further, according to the present invention, a spacer for uniformizing the gap between the substrates and a partition member for preventing the movement of the charged particles from pixel to pixel are not required. Therefore, there is no concern about a decrease in the optical aperture ratio due to the arrangement of these spacers and partition members.
[0132]
Furthermore, since microcapsules are not used, manufacturing is simplified.
[0133]
Further, when “a region having a high affinity for an insulating liquid” and “a region having a low affinity” are formed on the substrate surface by the above-described method, the position of the electrode and the position of the insulating liquid are determined. Can be matched exactly.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of the structure of an electrophoretic display device according to the present invention.
FIG. 2 is a sectional view showing another example of the structure of the electrophoretic display device according to the present invention.
FIG. 3 is a sectional view showing still another example of the structure of the electrophoretic display device according to the present invention.
FIG. 4 is a sectional view showing still another example of the structure of the electrophoretic display device according to the present invention.
FIG. 5 is a diagram for explaining the shape and the like of an electrode.
FIG. 6 is a schematic view illustrating an example of a method for manufacturing an electrophoretic display device according to the present invention.
FIG. 7 is a schematic view illustrating an example of a method for manufacturing an electrophoretic display device according to the present invention.
[Explanation of symbols]
1a First substrate
1b Second substrate
2 Coating
3 liquid
4 charged particles
5a, 5b electrode
6 Surface protective layer
16 Surface protective layer

Claims (27)

An electrophoretic display device that performs display based on dispersing charged particles in a liquid and moving the charged particles by applying an electric field,
A first substrate having electrodes,
A coating attached to the first substrate and forming a sealed portion between the first substrate and a surface of the first substrate;
Having a liquid in which the charged particles are dispersed, disposed in the closed portion,
An electrophoretic display device comprising: The sealing portion constitutes a pixel,
The electrophoretic display device according to claim 1, wherein: The first substrate has a pair of electrodes, and performs a display by applying a voltage between the pair of electrodes to move the charged particles in a substrate surface direction.
The electrophoretic display device according to claim 1, wherein: The pair of electrodes is a pair of a planar electrode below the sealed portion and an annular electrode surrounding the sealed portion,
The electrophoretic display device according to claim 3, wherein: A second substrate is disposed opposite the first substrate, and a top of the coating is in contact with the second substrate;
The electrophoretic display device according to claim 1, wherein: A second substrate having an electrode is disposed facing the first substrate, and a voltage is applied between the electrode of the first substrate and the electrode of the second substrate to cause the charged particles to fall between the first and second electrodes. Moving between the substrates to display
The electrophoretic display device according to claim 1, wherein: The coating is coated with a protective layer,
The electrophoretic display device according to claim 1, wherein: The first substrate has, on a surface thereof, a region having a high affinity for the liquid and a region having a low affinity, and the sealing portion is arranged in the region having a high affinity.
The electrophoretic display device according to claim 1, wherein: The high affinity region is surrounded by the low affinity region around,
The electrophoretic display device according to claim 8, wherein: The low affinity region is formed of a hydrophilic material,
The electrophoretic display device according to claim 8, wherein: The coating is made of a polymer material,
The electrophoretic display device according to claim 1, wherein: The polymer material is a polyamide resin, a polyurethane resin, a polyester resin, a polyurea resin, a polymelamine resin, an epoxy resin, a phenol resin, or a mixed resin thereof.
The electrophoretic display device according to claim 11, wherein: A method for manufacturing an electrophoretic display device that performs display based on dispersing charged particles in a liquid and moving the charged particles by applying an electric field,
Forming a region having a high affinity for the liquid and a region having a low affinity on the substrate surface,
Forming a droplet of liquid in which the charged particles are dispersed in the high affinity region,
Forming a film on a surface of the droplet that does not contact the substrate,
A method for manufacturing an electrophoretic display device. The step of forming the coating on the surface of the droplet that does not contact the substrate includes contacting the droplet with a liquid containing a polymer monomer or prepolymer that is a film-forming material to form a polymer on the surface of the droplet. Process
The method for manufacturing an electrophoretic display device according to claim 13, wherein: In the step of forming the film, the film-forming material contained in the liquid in contact with the droplet may be a polyvalent amine, a phenol, an aldehyde, a polyalcohol, a polybasic acid halide, a polyisocyanate, or a polyepoxide. Including two or more types selected from among
The method for manufacturing an electrophoretic display device according to claim 14, wherein: The step of forming a coating on the surface of the droplet that does not contact the substrate is a step of contacting the droplet with a solution obtained by dissolving the coating material in a solvent, and removing the solvent.
The method for manufacturing an electrophoretic display device according to claim 13, wherein: The coating material is polystyrene, acrylonitrile-styrene resin, polyvinyl formal, polyvinyl acetal, acrylic resin, or polyvinyl acetate,
The method for manufacturing an electrophoretic display device according to claim 16, wherein: The step of forming a film on a surface of the liquid in which the charged particles are dispersed contains a first film-forming material and not contacting the droplets with the substrate comprises converting the droplets into a liquid containing a second film-forming material. Contacting and reacting the first and second film-forming materials on the surface of the droplet.
The method for manufacturing an electrophoretic display device according to claim 13, wherein: The first film-forming material is a substance having a plurality of sites that undergo a condensation reaction with a compound having active hydrogen, and the second film-forming material is a compound having a plurality of active hydrogens.
The method for manufacturing an electrophoretic display device according to claim 18, wherein: The coating formed on the surface of the droplet is a polyurethane resin, a polyurea resin, a polyester resin, or a polyamide resin,
The method for manufacturing an electrophoretic display device according to claim 19, wherein: A contact angle of the droplet formed in the step of forming the droplet to the first substrate surface is 10 ° or more;
The method for manufacturing an electrophoretic display device according to claim 13, wherein: The step of forming the high affinity region and the low affinity region includes a step of partially disposing a hydrophilic material on a hydrophobic substrate surface.
The method for manufacturing an electrophoretic display device according to claim 13, wherein: The hydrophilic material is a hydrophilic resin,
The method for manufacturing an electrophoretic display device according to claim 22, wherein The hydrophilic resin is a polyalcohol, a polyacrylamide, a polysaccharide, a polycarboxylic acid or a mixture thereof,
The method for manufacturing an electrophoretic display device according to claim 23, wherein: The hydrophobic material is a hydrophobic resin,
The method for manufacturing an electrophoretic display device according to claim 22, wherein The hydrophobic resin is a polystyrene, a polyacrylester, a polyalkene or a mixture thereof,
The method for manufacturing an electrophoretic display device according to claim 25, wherein: The step of forming the high affinity region and the low affinity region includes a step of modifying a hydrophobic substrate surface to be hydrophilic.
The method for manufacturing an electrophoretic display device according to claim 13, wherein:

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