JP2006162901A - Electrophoretic display element and electrophoretic display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophoretic display element and an electrophoretic display device capable of preventing deterioration of display quality.
SOLUTION: A space S surrounded by a first substrate 1 and a second substrate 2 arranged with a predetermined gap and a partition wall 7 arranged in a gap between the first substrate 1 and the second substrate 2 is provided. Display is performed by arranging the charged particles 8 and changing the distribution of the charged particles 8 by the electric field generated between the first electrode 3 and the second electrode 4 arranged facing the gap. In the space S surrounded by the first substrate 3 and the second substrate 4 and the partition wall member 7, at least a part of the region having a high electric field strength between the first electrode 3 and the second electrode 4 is charged. By making at least one of the adhesion force and frictional force between the particles 8 stronger than the other regions, the occurrence of a decrease in the density of the charged particles is prevented.
[Selection] Figure 1

Description

  The present invention relates to an electrophoretic display element and an electrophoretic display device, and more particularly to a configuration for controlling the distribution of charged particles.

  Recently, an electrophoretic display device that performs display by applying a voltage for display control to a dispersion system in which electrophoretic charged particles are dispersed in an insulating liquid has attracted attention as a non-light-emitting display device. Has been.

  As an electrophoretic display element used in such an electrophoretic display device, a shielding layer is provided on the outside of a second substrate provided opposite to the first substrate provided with the first electrode, and the shielding is performed. There has been proposed one in which a second electrode is provided in a region concealed by a layer (see Patent Document 1).

  By the way, in an electrophoretic display device having such an electrophoretic display element, charged particles in an insulating liquid are moved by an electric field generated between the electrodes by applying a voltage to the first electrode and the second electrode. In this case, the brightness of the display is expressed by the density of charged particles distributed on the first electrode.

  Here, in order to control the distribution state of the charged particles, it is necessary to appropriately form a potential gradient between the first electrode and the second electrode. For example, in order to express only the color of the colored charged particles, the charged particles are distributed so as to cover the first electrode, and the reflected light from the first electrode is used to perform bright display. A distribution is formed so that charged particles are gathered in the vicinity of the two electrodes so that most of the incident light that has passed through the insulating liquid is directly incident on the first electrode.

  For example, when using black negatively charged particles as charged particles and using a white scattering layer as a scattering layer disposed on the first electrode to perform black and white display, By applying a negative voltage and applying a relatively positive voltage to the second electrode, the negatively charged charged particles move around the partition wall in the vicinity of the second electrode, thereby scattering. The white color that is the color of the layer will be visually recognized from the outside.

  On the other hand, when black display is performed, a positive voltage is applied to the first electrode and a relatively negative voltage is applied to the second electrode, so that the charged particles move onto the first electrode and are externally applied. The black color which is the color of the charged particles is visually recognized.

Japanese Patent Laid-Open No. 09-211499

  However, in the electrophoretic display device having such a conventional electrophoretic display element, when black display is performed by moving the charged particles onto the first electrode, the black luminance is reduced under the driving conditions that should originally perform black display. It was confirmed that the phenomenon slightly increased from the darkest brightness. As a result of detailed optical observation of this phenomenon, the charged particles 58 in the vicinity of the partition wall 57, which is the boundary portion between the first electrode 53 and the second electrode 54, at the time of black display as shown in FIG. It was found that the density decreased, white light leakage, which is the color of the scattering layer 56, occurred, and the black luminance was increased.

  Here, as a cause of such a deterioration in display quality, the area where the charged particle density in the vicinity of the barrier ribs has a parallel electric field component and a vertical electric field component, and the electric field is particularly strong even within the pixel. Since the second electrode 54 has the same polarity as the charged particles 58 during black display, the charged particles 58 are pushed out toward the center of the pixel due to electrostatic repulsion, and the particle density is increased in the vicinity of the partition wall. It is thought that it has decreased.

  Therefore, the present invention has been made in view of such a current situation, and an object of the present invention is to provide an electrophoretic element capable of preventing deterioration in display quality.

  The present invention includes a first substrate and a second substrate disposed in a state where a predetermined gap is provided, a partition member disposed in a gap between the first substrate and the second substrate, the first substrate and the second substrate, An electric field generated between the electrodes, comprising a plurality of pixels formed by charged particles disposed in a space surrounded by the partition wall member, and first and second electrodes disposed facing the gap. In the electrophoretic display element that performs display by changing the distribution of the charged particles according to the above, at least a part of a region having a high electric field strength between the first electrode and the second electrode in the space is used as the charged particle. It is characterized in that at least one of the adhesive force and the frictional force between the two is a region stronger than the other region.

  As in the present invention, at least a part of a region having a high electric field strength between the first electrode and the second electrode in the space surrounded by the first substrate and the second substrate and the partition member is charged particles. By preventing the occurrence of a decrease in the density of charged particles as a region where at least one of the adhesion force and the frictional force between them is stronger than the other regions, it is possible to prevent a reduction in display quality caused by a decrease in the density of charged particles.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an electrophoretic element according to an embodiment of the present invention. This electrophoretic display element is arranged with a first substrate 1 and a predetermined gap from the first substrate 1 for observation. Partition member that is disposed in the gap between the second substrate 2 disposed on the user side and the first and second substrates 1 and 2 so as to keep the gap constant and partitions the gap to define the pixel 10 A transparent insulating liquid 9 disposed in a space S formed by the partition wall 7, the first and second substrates 1 and 2 and the partition wall 7, and charged particles 8 dispersed in the insulating liquid 9, A first electrode 3 disposed on the pixel 10 along the first substrate 1 and a second electrode 4 formed inside the partition wall 7 are provided.

  In FIG. 1, reference numeral 6 denotes a scattering layer provided on the first electrode 3, but the scattering layer 6 may not be provided. Further, when the first electrode 3 is made of a transparent material, a reflective layer may be provided below the first electrode 3. The arrangement or shape of the first electrode 3 and the second electrode 4 is not limited.

  In the electrophoretic element having such a configuration, the charged particles 8 in the insulating liquid 9 are moved by the electric field generated between the electrodes by applying a voltage to the first electrode 3 and the second electrode 4. Display is done. Here, the brightness of the display is expressed by the density of the charged particles 8 distributed on the first electrode 3. In order to control the distribution state, the potential between the first electrode 3 and the second electrode 4 is controlled. It is necessary to form the gradient appropriately.

  For example, in order to express only the color of the colored charged particles 8, the charged particles 8 are distributed so as to cover the first electrode 3, and a bright display is made by using the reflected light from the first electrode 3. For this purpose, a distribution is formed so that the charged particles 8 are gathered in the vicinity of the second electrode 4 so that most of the incident light that has passed through the insulating liquid 9 is directly incident on the first electrode 3.

  By the way, as described above, of the surface of the scattering layer 6 that is in contact with the insulating liquid 9, the portion in the vicinity of the partition wall that is the boundary portion between the first electrode 3 and the second electrode 4 has an electric field in a direction parallel to the surface of the scattering layer 6. The portion having an electric field component perpendicular to the component and having a particularly strong electric field in the pixel, and the charged particles 8 in this portion are pushed out toward the center of the pixel, so that the charged particles 8 are covered with the first electrode 3. In the case where the particles are distributed, the particle density decreases near the partition walls.

  Therefore, in the present embodiment, as shown in FIG. 1, at least one of the adhesion force and the frictional force between the charged particles 8 in the contact state or the proximity state is provided in the vicinity of the partition wall where the charged particle density decreases. The particle adhering zone 5 is provided so as to form a region configured to be large.

  Then, such a particle adhesion band 5 is provided so that at least one of the adhesion force and the frictional force between the charged particles 8 and the charged particles 8 is increased in the vicinity of the partition wall, thereby covering the charged particles 8 with the first electrode 3. In this distribution, the charged particles 8 can be prevented from being pushed out to the center of the pixel.

  That is, by providing the particle adhesion band 5 in the vicinity of the partition wall 7 that forms a region where at least one of the adhesion force and the frictional force between the charged particles 8 in the contact state or the proximity state is stronger than the other part of the space S. Thus, it is possible to suppress the luminance change based on the decrease in the density of the charged particles 8. As a result, as shown in FIG. 2, there is no decrease in the particle density in the vicinity of the partition wall, and a decrease in display quality due to the decrease in particle density can be suppressed.

  It should be noted that at least one of the adhesion force and friction force of the particle adhesion band 5 is such a size that the charged particles 8 can be separated from the particle adhesion band 5 and gather in the vicinity of the partition wall when an electric field in the opposite direction is applied. Is set to

  Here, the particle adhesion band 5 is a region where the electric field strength is close to each of the first and second electrodes 3 and 4 and is preferably provided in a portion where the display quality deteriorates due to the decrease in the charged particle density. In the present embodiment, as shown in FIGS. 1 and 2, the scattering layer 6 is provided in the vicinity of the partition wall on the surface in contact with the insulating liquid, but inside the first substrate 1 as shown in FIG. In the case of the configuration in which the first electrode 3 is formed and the second electrode 4 is formed on the first substrate 1, the portion adjacent to the two electrodes 3, 4, that is, at the side end of the second electrode 4. It is preferable to provide the particle adhesion band 5.

  The particle adhesion band 5 is preferably transparent or the same color as the scattering layer 6. In this case, no reduction in reflectance from the scattering layer 6 due to the particle adhesion band 5 is observed. Further, the area and shape of the particle adhesion band 5 are not particularly limited. However, if the area is too large, the adhesion force increases in a region where the electric field strength is weaker, which may increase the driving voltage. For this reason, it is desirable to minimize the area.

  For this reason, when moving charged particles onto the first electrode, the charged particle density decreases, and the area and shape of the particle adhesion band 5 are determined in view of the area where the scattering layer 6 is exposed (hereinafter referred to as pixel opening area). It is necessary to calculate. For example, the pixel aperture area and its shape are calculated according to the actual situation based on the optical observation results when the charged particles are gathered around the second electrode and when the particles are moved onto the first electrode. It is also possible to do.

  Further, as a material for forming the particle adhesion band 5, at the time of forming the particle adhesion band 5, at least one of the adhesion force and the frictional force between the charged particles 8 in the insulating liquid is large, and the particle density reduction is suppressed. Any material may be used as long as it is effective. In addition, the adhesion force between the charged particles 8 and the particle adhesion band 5 may be substantially in a contact state, or may be a non-contact or attractive attraction force in a close state like Coulomb force.

  For example, when the adhesive force is generated by attractive force, an ionic material that is charged in the insulating liquid with a polarity opposite to that of the charged particles may be used. Here, as the ionic material, an ionic polymer having an ionic functional group having a large molecular weight is preferably used. In addition, as an ionic polymer, the homopolymer of an ionic monomer or the copolymer which consists of an ionic monomer and a nonionic monomer can be used. And as an ionic monomer, the following monomers are mentioned, for example.

  In the case of developing positive chargeability, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-hydroxy Aliphatic amino groups such as ethylaminoethyl (meth) acrylate, N-ethylaminoethyl (meth) acrylate, N-octyl-N-ethylaminoethyl (meth) acrylate, N, N-dihexylaminoethyl (meth) acrylate, etc. (Meth) acrylates, N-methylacrylamide, N-octylacrylamide, N-phenylmethylacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, Np-methoxy-phenylacrylamide, N, N-dimethylacrylamide, N N-dibutylacrylamide, (meth) acrylamides such as N-methyl-N-phenylacrylamide, aromatic substituted ethylene-based monomers having nitrogen-containing groups such as dimethylaminostyrene, diethylaminostyrene, dimethylaminomethylstyrene, dioctylaminostyrene , Vinyl-N-ethyl-N-phenylaminoethyl ether, vinyl-N-butyl-N-phenylaminoethyl ether, triethanolamine divinyl ether, vinyl diphenylaminoethyl ether, N-vinylhydroxyethylbenzamide, m- And nitrogen-containing vinyl ether monomers such as aminophenyl vinyl ether.

  Further, examples of nitrogen-containing basic monomers include nitrogen-containing heterocyclic compounds, among which pyrroles such as N-vinylpyrrole, N-vinyl-2-pyrroline, N-vinyl-3-pyrroline and the like. Pyrrolines, N-vinyl pyrrolidine, vinyl pyrrolidine amino ether, pyrrolidines such as N-vinyl-2-pyrrolidone, imidazoles such as N-vinyl-2-methylimidazole, imidazolines such as N-vinyl imidazoline, N-vinyl Indoles such as indole, indolines such as N-vinylindoline, N-vinylcarbazole, carbazoles such as 3,6-dibromo-N-vinylcarbazole, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5 -Pyridines such as vinylpyrrolidine, (meth) acrylic piperidine, N-vinyl pipette Don, piperidines such as N-vinylpiperazine, quinolines such as 2-vinylquinoline and 4-vinylquinoline, pyrazoles such as N-vinylpyrazole and N-vinylpyrazoline, oxazoles such as 2-vinyloxazole, 4-vinyl Oxazines such as oxazine and morpholinoethyl (meth) acrylate can also be used.

  In order to develop negative chargeability, for example, an ionic monomer having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, vinyl acetic acid, vinyl glycogenic acid, vinyl acrylic acid, vinyl benzoic acid, etc. Compound and its metal salt (Li, Na, K, Ca, Mg, Al, etc.), vinyl sulfonic acid, vinyl benzene sulfonic acid, vinyl benzyl sulfonic acid, vinyl benzene sulfinic acid etc. A compound having a functional group showing acidity such as a metal salt or phosphoric acid may be used alone or in combination of two or more.

  Alternatively, an electret material may be used as the particle adhesion band 5 and the electret treatment may be performed so as to be charged with a polarity opposite to that of the charged particles.

Here, as a material to be electretized, fluororesin such as Teflon (registered trademark) (Teflon-FEP, Teflon-TFE), polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyethylene terephthalate, polyimide, etc. Use. As an electret processing method, for example, 1. 1. A method in which a dielectric is heated to a softening temperature or near a melting temperature and cooled while applying a high electric field DC (thermo-electret method). 2. A method in which corona discharge is applied to the dielectric surface, or a high electric field DC (˜10 ⁶ V / cm) close to the dielectric breakdown voltage is applied at room temperature (electro-electret method). 3. A method of irradiating an insulator with high-energy radiation (electron beam, γ-ray) in a vacuum (radio electret method). 4. Method of applying high voltage DC during light irradiation (photo electret); Examples thereof include a method (mechanical / electret) by mechanical deformation by pressurization / stretching.

  As the particle adhesion band 5, any material may be used as long as the adhesion force for adhering the charged particles 8 in the insulating liquid is large. For example, when using a polystyrene-polymethyl methacrylate copolymer resin containing isoparaffin as the insulating liquid 9 and containing carbon black as the charged particles 8, an epoxy resin or polyethylene terephthalate (PET) can be used. However, it is not limited to these.

  In addition, as a method for quantitatively examining the adhesive force when selecting the adhesive material for forming the particle adhesion band 5, the charged particles 8 are adhered to the adhesive material, and the charged particles 8 that have adhered are removed from the adhesive material. Measure the strength of the shearing force in the dispersion necessary to leave, measure the electric field strength necessary for the charged particles 8 attached to leave the adhesive material, charge attached to the adhesive material For example, an area ratio per unit area of the particles 8 is obtained.

  Any method may be used to form the particle adhesion band. For example, the adhesive band material may be directly formed into a desired shape using photolithography, printing, etc., or a film made of the adhesive band material may be formed on the entire surface of the pixel, and then unnecessary portions may be removed. . Moreover, you may affix after forming in the shape of a particle adhesion band previously. Furthermore, a film made of an adhesive band material may be formed on the entire surface of the pixel, and the film may be covered with a film made of another material having a small adhesive force except where the adhesive band is to be provided, but is not limited thereto.

  Further, when the frictional force is increased, it is preferable to increase the frictional force by providing irregularities only in the vicinity of the partition wall on the surface of the scattering layer 6, for example, instead of directly forming the particle adhesion band into a desired shape. And by providing unevenness and increasing the frictional force in this way, it is possible to inhibit the charged particles 8 from moving along the surface of the scattering layer and to suppress a decrease in particle density. In addition, this unevenness | corrugation may be attached by dry etching using oxygen gas only in the area | region vicinity of the partition on the surface of the scattering layer 6, for example, and may be added by patterning a resist, for example using another material. Furthermore, means such as wet etching, pressing, cutting, anodizing, and laser processing may be used. Further, another material having a large frictional force may be used as the particle adhesion band.

  Next, other materials and manufacturing methods constituting the electrophoretic element according to the present embodiment will be described.

  For the first and second substrates 1 and 2, polymer films such as polyethylene terephthalate (PET), polyethersulfone (PES), polyimide (PI), polyethylene naphthalate (PEN), and polycarbonate (PC), glass In addition, an inorganic material such as quartz, or a stainless steel substrate having an insulating layer on the surface can be used. For the second substrate 2 on the observer side, a material having a high visible light transmittance, such as a transparent polymer film or glass, may be used.

  The first and second electrodes 3 and 4 are not particularly limited as long as they are conductive materials that can be patterned, and examples thereof include indium tin oxide (ITO), aluminum, and titanium. In the electrophoretic display device shown in FIGS. 1 and 2, the first electrode 3 is divided and formed for each pixel 10. However, the first electrode 3 may be formed on the entire pixel. It may be provided on the second substrate 2, and may be provided on both the first and second substrates 1 and 2.

  In addition, the second electrode 4 is provided inside the partition wall, but the side surface, bottom surface, or part sandwiched between the partition wall 7 and the second substrate 2 or the partition wall 7 and the first substrate as shown in FIG. You may provide in the part pinched | interposed into 1.

  Furthermore, an insulating layer may be formed so as to cover the first and second electrodes 3 and 4, and when such an insulating layer is formed, charge injection from the electrodes 3 and 4 to the charged particles 8 can be prevented. . Note that a material used for the insulating layer is preferably a thin film in which pinholes are difficult to be formed. Specific examples include a highly transparent polyimide resin, polyester resin, polyacrylate resin, polymethacrylate resin, polycarbonate resin, polyarylate resin, novolac resin, and epoxy resin. When forming the insulating layer, the particle adhesion band may be formed on the insulating liquid 6 side from the insulating layer.

  A polymer resin may be used for the partition wall 7. Specific examples include polyimide resins, polyester resins, polyacrylate resins, polymethacrylate resins, polycarbonate resins, polyarylate resins, novolac resins, and epoxy resins. In addition, as a method of forming the partition wall 7, a method of performing exposure and wet development after applying a photosensitive resin layer, a method of forming by a printing method, a method of bonding to a substrate after forming a partition wall, a light-transmitting property The method etc. which form with a mold on the substrate surface can be mentioned.

  By the way, the area | region in which any one electrode is arrange | positioned among the 1st and 2nd electrodes 3 and 4 is given the same color as the charged particle 8, and the area | region in which the other electrode is arrange | positioned is colored in a different color. can do. In this case, the electrode itself may be colored, or a colored layer may be provided separately from the electrode, and the insulating layer may be disposed so as to overlap the electrode, and the insulating layer may be colored. Further, when used as a white display, it is preferable to provide surface irregularities so that light is irregularly reflected on the electrode surface itself, or to form a light scattering layer on the electrode.

Here, as a material constituting the scattering layer 6, it is preferable to include highly reflective fine particles in a transparent insulating resin, and titanium oxide, Al ₂ O _3, or the like is suitably used as the fine particles. As the transparent resin, acrylic resin, urethane resin, fluorine resin, norbornene resin, PC, PET, or the like can be used.

  The average particle size of the charged particles 8 is preferably in the range of 0.1 μm to 10 μm. The colorant is not particularly limited. Blue, phthalocyanine green, sky blue, rhodamine lake and the like can be mentioned.

  Examples of the particle resin include polyethylene such as polystyrene, polyethylene, polyester, polymethacrylate, polyacrylate, polyacrylate, polyethylene-acrylic acid copolymer, polyethylene-methacrylic acid copolymer, polyethylene-vinyl acetate copolymer. And other high molecular weight materials such as polyvinyl chloride resin, nitrocellulose, phenol resin, and polyamide resin. These materials may be used alone or in combination of two or more.

  As the insulating liquid 9, a highly insulating organic solvent having low conductivity can be used. For example, aromatic hydrocarbon solvents such as benzene, toluene, xylene, hexane, cyclohexane, paraffin hydrocarbon solvents, aliphatic hydrocarbon solvents such as isoparaffin hydrocarbons and naphthene hydrocarbons, halogenated hydrocarbon solvents In addition, silicon oil, high-purity petroleum, and the like can be mentioned. Among them, aliphatic hydrocarbon solvents are preferably used. Specifically, Isopar G, H, M, L (all manufactured by Exxon Chemical Co., Ltd.), Shellsol (Showa) Shell Japan), IP solvent 1016, 1620, 2028, 2835 (Idemitsu Petrochemical). These can be used alone or in admixture of two or more.

  Note that a charge control agent for controlling and stabilizing the charging of the charged particles 8 may be added to the above-described insulating liquid or charged particles. As such a charge control agent, a metal complex salt of a monoazo dye, salicylic acid, an organic quaternary ammonium salt, a nigrosine compound, or the like may be used.

  In addition, a dispersing agent for preventing aggregation of charged particles and maintaining a dispersed state may be added to the insulating liquid. As such a dispersing agent, polyvalent metal phosphates such as calcium phosphate and magnesium phosphate, carbonates such as calcium carbonate, other inorganic salts, inorganic oxides, or organic polymer materials can be used. These charge control agents and dispersants can be used alone or in combination of two or more.

  As described above, in the space S surrounded by the first substrate 1 and the second substrate 2 and the partition wall 7, at least a part of a region having a high electric field strength between the first electrode 3 and the second electrode 4. By preventing the occurrence of a decrease in the density of the charged particles 8 as a region where at least one of the adhesion force and the frictional force with the charged particles 8 is stronger than the other regions, Decline can be prevented.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
In this example, the electrophoretic display device shown in FIG. 1 was produced as follows.

  First, aluminum is vapor-deposited with a thickness of 100 nm on the surface of the first substrate 1 made of a 1.1 mm thick glass substrate, and patterned using a photolithography technique to form the first electrode 3 and a wiring (not shown). Next, a polyurethane resin layer that is whitened by mixing fine titanium oxide particles is formed on the surface of the first electrode 3 to form the scattering layer 6.

  Next, a particle adhesion band 5 made of a photosensitive epoxy resin is provided on the surface of the scattering layer 6 by a photolithography technique. Here, the film thickness of this particle adhesion band is 1.5 μm and the line width is 26 μm so as to surround the pixel.

  Next, the second electrode 4 is provided on the particle adhesion zone. Here, the second electrode 4 is made of copper using a plating method, and has a height of 10 μm and an electrode width of 7 μm. Further, a partition wall 7 is formed so as to overlap the second electrode 4. Here, the partition walls 7 are formed by a photolithography technique using a photosensitive epoxy resin. The partition 7 has a width of 12 μm and a height from the insulating layer of 20 μm. By forming the partition wall 7 in this way, the particle adhering body 5 protrudes by 7 μm on both sides from the partition wall 7.

  Next, each pixel is filled with an insulating liquid 9 and charged particles 8. For the insulating liquid 9, isoparaffin (trade name: Isopar, manufactured by Exxon) is used, and for the charged particles 8, a polystyrene-polymethyl methacrylate copolymer resin containing carbon black having a particle size of about 1 to 2 μm is used. Isoparaffin contains succinimide (trade name: OLOA 1200, manufactured by Chevron) as a charge control agent. Next, the 2nd board | substrate 2 is arrange | positioned on a partition, the voltage application means not shown is connected to the 1st and 2nd electrodes 1 and 2, and an electrophoretic display element is obtained.

  A voltage is applied to the electrophoretic display element obtained as described above, and the display state is observed. Here, when the second electrode 4 is set to the ground potential and a positive polarity voltage is applied to the first electrode 3, the charged particles 8 move to the vicinity of the side wall of the partition wall 7, and the scattering layer 6 on the second substrate is exposed. White display. Further, when a negative polarity voltage is applied to the first electrode to move the charged particles onto the first electrode, the charged particles 8 move onto the first electrode, and a good black display without white spots is obtained.

  As a comparative example, when a voltage is applied to the electrophoretic display element formed in the same manner as in Example 1 except that the particle adhesion band 5 is not provided on the scattering layer 6, and the display state is observed, the first electrode is negative. When a polar voltage was applied and the charged particles were moved onto the first electrode, white spots were observed due to the scattering layer being visually recognized in the vicinity of the second electrode, and the display quality in the black display state was lowered.

(Example 2)
In this example, the process up to the formation of the scattering layer 6 is the same as that of Example 1, and thereafter, the part where the particle adhesion band is formed in Example 1 is uncoated using a photolithography technique. A mask is formed. Next, irregularities are formed on the surface of the uncoated scattering layer 6 by dry etching using oxygen plasma to form particle adhesion bands, and then the mask is removed. Thereafter, an electrophoretic display element is obtained in the same manner as in Example 1.

  When a voltage was applied to the electrophoretic display element thus obtained and the display state was observed, the same effect as in Example 1 was obtained.

(Example 3)
In this example, the process up to the formation of the scattering layer 6 is the same as in Example 1, and thereafter, as shown in FIG. 5, the particle adhesion band 5 made of an epoxy resin is provided on the entire surface of the pixel without patterning, and on the surface. The coating layer 11 made of an acrylic resin having a smaller adhesion force of charged particles than that of the epoxy resin is formed so as not to cover only the peripheral portion of the pixel. Thereafter, an electrophoretic display element is obtained in the same manner as in Example 1. When a voltage was applied to the electrophoretic display element thus obtained and the display state was observed, the same effect as in Example 1 was obtained.

The figure which shows the structure of the electrophoretic element which concerns on embodiment of this invention. The figure which shows the black display state of the said electrophoretic element. The figure which shows the other structure of the said electrophoretic element. The figure which shows the other structure of the said electrophoretic element. The figure which shows the other structure of the said electrophoretic element. The figure which shows the black display state of the conventional electrophoretic element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 2nd board | substrate 3 1st electrode 4 2nd electrode 5 Particle adhesion zone 6 Scattering layer 7 Partition 8 Charged particle 9 Insulating liquid 10 Pixel 11 Coat layer S Space

Claims (5)

A first substrate and a second substrate disposed in a state where a predetermined gap is provided; a partition member disposed in a gap between the first substrate and the second substrate; the first substrate, the second substrate and the partition member; A plurality of pixels formed by a charged particle disposed in a space surrounded by a first electrode and a second electrode disposed facing the gap, and the charged particle is generated by an electric field generated between the electrodes. In an electrophoretic display element that performs display by changing the distribution of
Of the space, at least part of a region where the electric field strength is strong between the first electrode and the second electrode, and at least one of adhesion force and friction force between the charged particles is stronger than other regions. An electrophoretic display element characterized in that it is a region.   The electrophoretic display element according to claim 1, wherein the region where the adhesive force is stronger than the other region is formed of a material having a strong attractive force between the charged particles.   The electrophoretic display element according to claim 1, wherein the region where the frictional force is stronger than the other region is formed with unevenness in a portion in contact with the charged particle in the region.   The first electrode is provided on at least one of the first substrate and the second substrate, and the second electrode is disposed on a side surface, a bottom surface, the inside of the partition member, or at least the partition member and the first substrate and the second substrate. 4. The device according to claim 1, wherein the region having a strong electric field strength is provided in the vicinity of a closest portion between the partition wall member and the first electrode. 2. The electrophoretic display element according to item 1. An electrophoretic display device comprising the electrophoretic display element according to claim 1.

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