JP2006058559A - Image display panel and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display panel having little variance in film thickness or film quality within a substrate and having uniform characteristics as an image display panel within the substrate, and to provide a method for manufacturing the same. <P>SOLUTION: The image display panel contains an image display medium 3 sealed between two substrates 1, 2 at least one of which is transparent and the panel displays an image by moving the image display medium by applying a voltage on electrodes 5, 6 laid on the substrate to apply an electric field on the display medium, wherein an insulating film 11 of a metal oxide produced by an anodic oxidation method is formed on a metal electrode. The insulating film 11 is obtained by connecting all metal electrodes on the substrate and dummy electrodes laid on the substrate edge, immersing the substrate in an anodic oxidation liquid while only the dummy electrodes are kept out of the liquid, immersing a platinum plate, and applying a voltage with the dummy electrode as a plus terminal and the platinum plate as a minus terminal to form an insulating film of the metal oxide on the metal electrode by an anodic oxidation method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention moves an image display medium by enclosing an image display medium between two substrates, at least one of which is transparent, and applying an electric field to the image display medium by applying a voltage to an electrode provided on the substrate. The present invention relates to an image display panel for displaying an image and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, image display devices using techniques such as an electrophoresis method, an electrochromic method, a thermal method, and a two-color particle rotation method have been proposed as image display devices that can replace liquid crystal (LCD).

  Compared to LCDs, these conventional technologies have advantages such as a wide viewing angle close to that of ordinary printed materials, low power consumption, and a memory function. It is considered as a technology that can be used for mobile phones, and is expected to expand to image display for mobile terminals, electronic paper, and the like. Particularly recently, an electrophoretic method in which a dispersion liquid composed of dispersed particles and a colored solution is encapsulated and disposed between opposing substrates has been proposed and is expected.

  However, the electrophoresis method has a problem that the response speed becomes slow due to the viscous resistance of the liquid because the particles migrate in the liquid. Furthermore, since particles with high specific gravity such as titanium oxide are dispersed in a solution with low specific gravity, it is easy to settle, and it is difficult to maintain the stability of the dispersed state, and there is a problem of lack of image repetition stability. . Even when microencapsulation is performed, the cell size is set to the microcapsule level, and the above-described drawbacks are hardly made to appear, and the essential problems are not solved at all.

  On the other hand, a method in which conductive particles and a charge transport layer are incorporated into a part of a substrate without using a solution is proposed instead of an electrophoresis method using behavior in a solution (see, for example, Non-Patent Document 1). ). However, the structure is complicated because the charge transport layer and further the charge generation layer are arranged, and it is difficult to inject the charges into the conductive particles.

As one method for solving the various problems described above, an image display medium is sealed between two substrates, at least one of which is transparent, and an electric field is applied to the image display medium by applying a voltage to an electrode provided on the substrate. An image display panel that displays an image by moving an image display medium by applying the image display medium is known.
趙 Kuniori and three others, “New Toner Display Device (I)”, July 21, 1999, Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcopy'99” Proceedings, p.249-252

  In the above-described image display panel, conventionally, an (inorganic) insulating film is conventionally formed on the electrode by sputtering, vapor deposition, CVD so as to prevent the adhesion between the electrode and the image display medium and smooth movement of the image display medium. Or the sol-gel method. However, since the (inorganic) insulating film produced by the conventional method has a large variation in film thickness and film quality within the substrate, the characteristics (driving voltage, contrast, etc.) of the image display panel vary within the substrate. It has occurred.

  An object of the present invention is to solve the above-described problems, and provide an image display panel in which variations in film thickness and film quality in the substrate are small and characteristics as an image display panel do not vary within the substrate, and a method for manufacturing the same. It is something to try.

  The image display panel of the present invention encloses an image display medium between two substrates, at least one of which is transparent, and applies an electric field to the image display medium by applying a voltage to an electrode provided on the substrate. In an image display panel that displays an image by moving an image display medium, a metal oxide insulating film formed by an anodic oxidation method is formed on a metal electrode.

  As a suitable example of the image display panel of the present invention, a metal oxide insulating film is formed on an electrode other than the metal electrode by a method other than the anodic oxidation method, and the image display medium is a particle group or a powder fluid. There is, there is.

  The image display panel manufacturing method of the present invention is the method for manufacturing an image display panel having the above-described configuration, wherein all the metal electrodes on the substrate and the dummy electrodes provided on the substrate end are connected, and anodization is performed. In the liquid, only the dummy electrode is immersed in the anodic oxidation solution, the substrate is immersed, the platinum plate is immersed, the dummy electrode is a positive electrode, the platinum plate is a negative electrode, and a voltage is applied, A metal oxide insulating film is formed on the metal electrode by an anodic oxidation method.

  In the present invention, since the metal oxide insulating film formed by the anodic oxidation method is formed on the metal electrode, the insulating film can be formed uniformly, even if the other electrode is not a metal electrode and the insulating film is an anode. Even if it has an insulating film formed by a method other than the oxidation method, variations in film thickness and film quality within the substrate can be reduced, and an image display panel in which characteristics as an image display panel do not vary within the substrate is obtained. be able to.

  First, a basic configuration of an image display panel that is an object of the present invention will be described. In the image display panel used in the present invention, an electric field is applied to an image display medium sealed between two opposing substrates. Along with the applied electric field direction, the image display medium charged at a low potential toward the high potential side is attracted by the force of the electric field or the Coulomb force, and is charged at a high potential toward the low potential side. The image display medium is attracted by an electric field force, a Coulomb force, or the like, and the image display medium is reciprocated by a change in the electric field direction due to the potential switching, thereby displaying an image. Therefore, it is necessary to design the image display panel so that the image display medium moves uniformly and can maintain stability during repetition or storage. Here, as the force applied to the particles constituting the image display medium, in addition to the force attracted by the Coulomb force between the particles, the electric image force with the electrode and the substrate, the intermolecular force, the liquid cross-linking force, gravity and the like can be considered. .

An example of an image display panel which is an object of the present invention will be described with reference to FIGS. 1 (a) and (b) to FIGS. 2 (a) and 2 (b).
In the example shown in FIGS. 1 (a) and 1 (b), an image display medium 3 (here, white particles 3W and black particles 3B) having different colors and charging characteristics composed of at least one kind of particles is used as a substrate. 1 is moved perpendicularly to the substrates 1 and 2 in accordance with the electric field generated by applying a voltage between the electrode 6 provided on the electrode 1 and the electrode 5 provided on the substrate 2 to make the black particles 3B visible to an observer. Thus, black display is performed, or white particles 3W are visually recognized by an observer to perform white display. In the example shown in FIG. 1B, in addition to the example shown in FIG. 1A, partition walls 4 are provided, for example, in a lattice shape between the substrates 1 and 2 to define display cells.
In the example shown in FIGS. 2A and 2B, a voltage is applied between the electrode 5 and the electrode 6 provided on the substrate 2 with the image display medium 3 (here, white particles 3 W) of one kind of color. The white particles 3W are moved in the direction parallel to the substrates 1 and 2 in accordance with the electric field generated by the display, and the white particles 3W are visually recognized by the observer, or the color of the electrode 6 or the substrate 1 is given to the observer. The color of the electrode 6 or the substrate 1 is displayed by visual recognition. In the example shown in FIG. 2B, in addition to the example shown in FIG. 2A, partition walls 4 are provided, for example, in a lattice form between the substrates 1 and 2 to define display cells.
The above description can be similarly applied to the case where the white particles 3W are replaced with the white powder fluid and the black particles 3B are replaced with the black powder fluid.

FIG. 3 is a diagram showing the configuration of an example of the image display panel of the present invention. In the example shown in FIG. 3, a transparent ITO electrode 6 is provided on the transparent front substrate 1, and a metal electrode 5 made of aluminum is provided on the opaque back substrate 2. A feature of the image display panel of the present invention shown in FIG. 3 is that an insulating film 11 of aluminum oxide (Al ₂ O ₃ ) formed by anodic oxidation is formed on the metal electrode 5. Since the ITO electrode 6 is not a metal and an anodic oxidation method cannot be applied, an insulating film 12 made of aluminum oxide is formed on the ITO electrode 6 by sputtering or the like. As described in the prior art, the insulating film 12 formed by sputtering or the like is inferior in uniformity as compared with the insulating film 11 formed by the anodic oxidation method. This is effective in eliminating variations in characteristics (drive voltage, contrast, etc.) within the substrate. Further, the anodic oxidation method can obtain uniformity even when the insulating films are collectively provided in a large area.

  Next, the manufacturing method of the image display panel of the present invention will be described. FIGS. 4A to 4D are views showing an example of a method for manufacturing an image display panel according to the present invention in the order of steps. The manufacturing method of the image display panel according to the present invention will be described with reference to FIGS. 4A to 4D. First, as shown in FIG. 4A, all the metal electrodes 5 on the back substrate 2 and the back substrate 2 are used. The connection pattern 14 is connected to the dummy electrode 13 provided at the end portion (the end portion on the upper side when immersed in the anodizing solution as will be described later). Next, as shown in FIGS. 4B and 4C, the back substrate 2 is immersed in the anodizing solution 15 with only the dummy electrode 13 taken out from the anodizing solution 15, and the back substrate 2 and A platinum plate 16 having substantially the same size is immersed in the anodizing solution. Then, the connecting wire 17 and the alligator clip 18 are used to connect the positive electrode of the power supply device (not shown) and the dummy electrode 13 and the negative electrode of the power supply device and the platinum plate 16. In this state, a predetermined voltage is applied between the metal electrode 5 on the back substrate 2 and the platinum plate 16 from a power supply device (not shown) to perform anodization. In the anodic oxidation, the positive side is oxidized, so that an insulating film 11 made of aluminum oxide is formed on the metal electrode 5 made of aluminum and the connection pattern 14 as shown in FIG.

  FIGS. 5A to 5D are views showing another example of the image display panel manufacturing method of the present invention in the order of steps. In the example shown in FIGS. 5A to 5D, the same members as those in the example shown in FIGS. 4A to 4D are denoted by the same reference numerals, and the description thereof is omitted. The example shown in FIGS. 5A to 5D is different from the example shown in FIGS. 4A to 4D in the example shown in FIGS. 4A to 4D. In the example shown in FIGS. 5 (a) to 5 (d), a plurality of back substrates 2 are used, while only one mother substrate for taking a large number of back substrates 2 is used to perform anodization. Alternatively, anodization is performed using a plurality of mother substrates for obtaining a plurality of back substrates 2. As shown in FIGS. 5A to 5D, when anodization is performed using a plurality of rear substrates 2 or a plurality of mother substrates for taking a plurality of back substrates 2, This is preferable because the thickness of the insulating film 11 obtained by anodization can be made uniform, in other words, the thickness of the insulating film 11 in the lot can be made uniform.

  In the above-described anodic oxidation method, as the anodic oxidation solution 15, generally an acidic aqueous solution such as sulfuric acid, oxalic acid, phosphoric acid or citric acid, or a neutral aqueous solution such as borate or phosphate can be used. In addition to aluminum, magnesium, tantalum, titanium, zirconium, or the like can be used as the metal electrode 5.

  FIG. 6 is a view for explaining a specific example of anodic oxidation in the method for producing an image display panel of the present invention. In the example shown in FIG. 6, 21 is a container, 22 is an electrolytic solution as an anodizing solution 15 accommodated in the container 21, 23 is an anode plate made of a glass substrate 2 provided with an aluminum electrode 5 having a thickness of 300 nm, Reference numeral 24 denotes a cathode plate made of the platinum plate 15, and 25 denotes a power supply device. In this example, a 15% aqueous solution of sulfuric acid is used as the electrolytic solution 22, and the distance between the plates between the anode plate 23 and the cathode plate 24 is set to 10 cm. In this state, a DC voltage is applied from the power supply device 25 so that the anode plate 23 is positive and the cathode plate 24 is negative. The method of applying the DC voltage is a schedule of increasing from 0 to 20 V over 30 minutes. As a result, a 100 nm oxide film was formed on the surface of the aluminum electrode 5. Further, the film thickness distribution of the oxide film is within ± 5% within a 30 cm square substrate. If an image display panel is produced using this substrate 2, variations in driving voltage and contrast are reduced.

In the present invention, the insulating film 12 having the following excellent characteristics can be obtained by forming the insulating film by an anodic oxidation method.
(1) The film thickness can be easily set (the film thickness is determined by the applied voltage).
(2) The film thickness distribution is very small (current does not flow due to the formation of the insulating film).
(3) The film quality becomes dense (formation of a barrier film) as compared with other film forming methods (sputtering, vapor deposition, etc.).
(4) Wide range of applicable metal species (Al, Mg, Ta, Ti, Zr, Hf, Si, Ge, etc.).
(5) The apparatus is simple and the introduction cost is low.
(6) This technology is widely used (alumite treatment, Ta ₂ O _{5 of} TFD element).

  In the present invention, the thickness of the thin insulating film can be measured using a film thickness meter, an ellipsometer, an optical interferometer, or the like. Here, the ellipsometer method means ellipsometry, and the optical properties (film thickness, refractive index) of the sample can be determined by analyzing the difference between the polarization state of the incident light and the reflected light on the sample. It is a method of measuring. According to this method, the film thickness of the transparent film can be measured, and if the refractive index is different, the multilayer transparent film can also be measured.

  Hereinafter, each member which comprises the image display panel used as the object of this invention is demonstrated.

  About the partition provided as needed, the shape is appropriately set appropriately depending on the type of the image display medium involved in the display, and is not limited in general, but the width of the partition is 2 to 100 μm, preferably 3 to 50 μm. The height is adjusted to 10 to 500 μm, preferably 10 to 200 μm. As shown in FIG. 7, the display cells formed by the partition walls made of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the substrate plane direction. The shape and the mesh shape are exemplified. It is better to make the portion corresponding to the cross section of the partition wall visible from the display side (the area of the frame portion of the display cell) as small as possible, and the sharpness of the image display increases.

  As for the substrate, at least the substrate on the viewer side is a transparent substrate in which the color of the image display medium can be confirmed from the outside of the image display panel, and a material having high visible light transmittance and good heat resistance is suitable. . The substrate which is the other back side substrate may be transparent or opaque. Examples of substrate materials include polymer sheets such as polyethylene terephthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and flexible materials such as glass and quartz. There are no inorganic sheets. The thickness of the transparent substrate is preferably 2 to 5000 μm, more preferably 5 to 2000 μm, and the thickness of the back substrate is preferably 20 to 5000 μm, and more preferably 30 to 2000 μm. If any of the substrates is too thin, it is difficult to maintain the strength and the uniformity between the substrates, and if it is thicker than 5000 μm, it is inconvenient for an image display panel mounted on a thin image display device.

  Regarding the electrode provided as necessary, the electrode 6 provided on the substrate side which needs to be transparent on the viewing side is formed of a conductive material which is transparent and can be patterned, and is aluminum, silver, nickel, copper, gold Metals such as ITO, conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene are exemplified and used as appropriate. . As a method for forming an electrode, a method of forming the above-described materials into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or mixing a conductive agent with a solvent or a synthetic resin binder. The method of apply | coating is used. Note that the electrode thickness is not particularly limited as long as the conductivity can be secured and the light transmittance is not hindered, and is preferably 3 to 1000 nm, preferably 5 to 400 nm. The material, thickness, and the like of the electrode 5 provided on the substrate side on the back side are the same as those of the electrode 6 described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

  Next, the powder fluid as an image display medium used in the image display panel of the present invention will be described. As for the name of the powder fluid as the image display medium of the present invention, the present applicant has obtained the right of “Electronic Powder Fluid (registered trademark)”.

  The “powder fluid” in the present invention is a substance in an intermediate state of both fluid and particle characteristics that exhibits fluidity by itself without borrowing the force of gas or liquid. For example, a liquid crystal is defined as an intermediate phase between a liquid and a solid, and has fluidity that is a characteristic of a liquid and anisotropy (an optical property) that is a characteristic of a solid (Heibonsha: Encyclopedia). . On the other hand, the definition of particle is an object with a finite mass even if it is negligible, and is said to be affected by gravity (Maruzen: Physics Encyclopedia). Here, even in the case of particles, there are special states of gas-solid fluidized bed and liquid-solid fluids. When gas is flowed from the bottom plate to the particles, upward force is applied to the particles according to the velocity of the gas. Is a gas-solid fluidized bed that is in a state where it can easily flow when it balances with gravity, and it is also called a liquid-solid fluidized state that is fluidized by the fluid (ordinary) Company: Encyclopedia). As described above, the gas-solid fluidized bed body and the liquid-solid fluid body are in a state using a flow of gas or liquid. In the present invention, it has been found that a substance in a state of fluidity can be produced specifically without borrowing the force of such gas and liquid, and this is defined as powder fluid.

  That is, the pulverulent fluid in the present invention is in an intermediate state having both the characteristics of particles and liquid, as in the definition of liquid crystal (liquid and solid intermediate phase), and is the characteristic of the above-mentioned particles. It is a substance that is extremely unaffected and exhibits a unique state with high fluidity. Such a substance can be obtained in an aerosol state, that is, a dispersion system in which a solid or liquid substance is stably suspended as a dispersoid in a gas, and the solid substance is used as a dispersoid in the image display device of the present invention. Is.

The image display panel of the present invention is a powder fluid exhibiting high fluidity in an aerosol state in which solid particles are stably suspended as a dispersoid, for example, as an image display medium between two opposing substrates, at least one of which is transparent. Such a powder fluid can be easily and stably moved by a Coulomb force by applying a low voltage.
As described above, for example, the powder fluid used in the present invention is a substance in an intermediate state between fluid and particles, which exhibits fluidity by itself without borrowing the force of gas or liquid. This powder fluid can be in an aerosol state in particular, and in the image display device of the present invention, a solid substance is used in a state of relatively stably floating as a dispersoid in the gas.

  Next, the particles as the image display medium used in the image display panel of the present invention will be described. The particles can contain a charge control agent, a colorant, an inorganic additive, and the like, if necessary, in the resin as the main component, as in the conventional case. Examples of resins, charge control agents, colorants, and other additives will be given below.

  Examples of the resin include urethane resin, urea resin, acrylic resin, polyester resin, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluororesin, acrylic fluororesin, silicone resin, acrylic silicone resin, epoxy resin, polystyrene resin, styrene Acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluororesin, polycarbonate resin, polysulfone resin, polyether resin, polyamide resin and the like can be mentioned, and two or more kinds can be mixed. In particular, acrylic urethane resin, acrylic silicone resin, acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are suitable from the viewpoint of controlling the adhesive force with the substrate.

  The charge control agent is not particularly limited. Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, metal-containing oil-soluble dyes (including metal ions and metal atoms), and quaternary ammonium salt systems. Examples thereof include compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), and nitroimidazole derivatives. Examples of the positive charge control agent include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and the like. In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide, ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen, etc. are also charged. It can also be used as a control agent.

  As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.

Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.
Examples of blue colorants include C.I. I. Pigment blue 15: 3, C.I. I. Pigment Blue 15, Bituminous Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC and the like.
Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risor red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2 etc.

Yellow colorants include chrome yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12 etc.
Examples of green colorants include chrome green, chromium oxide, pigment green B, C.I. I. Pigment Green 7, Malachite Green Lake, Final Yellow Green G, etc.
Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment Orange 31 etc.
Examples of purple colorants include manganese purple, first violet B, and methyl violet lake.
Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

  Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.
These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferable as the black pigment, and titanium oxide is preferable as the white pigment.

  Moreover, it is preferable that the particles used as the image display medium used in the image display panel of the present invention have an average particle diameter d (0.5) in the range of 0.1 to 20 μm and are uniform and uniform. If the average particle diameter d (0.5) is larger than this range, the display is not clear, and if it is smaller than this range, the cohesive force between the particles becomes too large, which hinders the movement of the particles.

Furthermore, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is set to less than 5, preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(However, d (0.5) is a numerical value indicating the particle diameter in μm that 50% of the particles are larger than this, and 50% is smaller than this, and d (0.1) is a particle in which the ratio of the smaller particles is 10%. (Numerical value expressed in μm, and d (0.9) is a numerical value expressed in μm for a particle size of 90% or less.)
By keeping Span within a range of 5 or less, the size of each particle is uniform and uniform particle movement is possible.

  Furthermore, regarding the correlation between the particles, the ratio of d (0.5) of the particles having the minimum diameter to d (0.5) of the particles having the maximum diameter among the used particles is set to 50 or less, preferably 10 or less. It is essential.

The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. When laser light is irradiated onto particles to be measured, a light intensity distribution pattern of diffracted / scattered light is spatially generated, and this light intensity pattern has a corresponding relationship with the particle diameter, so that the particle diameter and particle diameter distribution can be measured. .
Here, the particle size and particle size distribution in the present invention are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring instrument, particles are introduced into a nitrogen stream, and the attached analysis software (software based on volume-based distribution using Mie theory) The diameter and particle size distribution can be measured.

  The charge amount of the particles constituting the image display medium naturally depends on the measurement conditions, but the charge amount of the particles constituting the image display medium in the image display panel is almost equal to the initial charge amount, contact with the partition walls, and the substrate. It was found that the saturation value of the charging behavior of the particles constituting the image display medium is a dominant factor, depending on the charge decay with contact and elapsed time.

Furthermore, in the present invention, when a particle group or powder fluid is used for the image display medium, it is important to manage the gas in the void surrounding the image display medium 3 (particle group or powder fluid) between the substrates, and display stability is improved. Contribute to. Specifically, it is important that the relative humidity at 25 ° C. is 60% RH or less, preferably 50% RH or less, more preferably 35% RH or less with respect to the humidity of the gas in the gap.
This void portion refers to the electrodes 5 and 6, the image display medium (particles) from the portion sandwiched between the opposing substrate 1 and substrate 2 in FIGS. 1 (a) and (b) to FIGS. It refers to a gas portion in contact with a so-called image display medium, excluding a group or powdered fluid 3) occupied portion, a partition 4 occupied portion (portion where the partition wall exists), and a device seal portion.
The gas in the gap is not limited as long as it is in the humidity region described above, but dry air, dry nitrogen, dry argon, dry helium, dry carbon dioxide, dry methane, and the like are preferable. This gas needs to be sealed in the panel so that the humidity is maintained. For example, the image display medium is filled and the panel is assembled in a predetermined humidity environment. It is important to apply a sealing material and a sealing method to prevent the above.

  The volume occupancy of the image display medium (particle group or powder fluid) in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. When it exceeds 70%, the movement of the image display medium (particle group or powder fluid) is hindered, and when it is less than 5%, the contrast tends to be unclear.

  The image display panel of the present invention includes a display unit of a mobile device such as a notebook computer, a PDA, a mobile phone, and a handy terminal, an electronic book, an electronic paper such as an electronic newspaper, a bulletin board such as a signboard, a poster, and a blackboard, a calculator, and a home appliance. It is suitably used for display parts for automobile supplies, card display parts such as point cards and IC cards, electronic advertisements, electronic POPs, electronic price tags, electronic musical scores, and display parts for RF-ID devices.

(A), (b) is a figure which shows operation | movement of an example of the image display panel of this invention, respectively. (A), (b) is a figure which shows the operation | movement of the other example of the image display panel of this invention, respectively. It is a figure which shows the structure of an example of the image display panel of this invention. (A)-(d) is a figure which shows an example of the manufacturing method of the image display panel of this invention in order of a process, respectively. (A)-(d) is a figure which shows the other example of the manufacturing method of the image display panel of this invention in order of a process. It is a figure for demonstrating the specific example of the anodic oxidation in the manufacturing method of the image display panel of this invention. It is a figure which shows an example of the shape of the partition in the image display panel used as the object of this invention.

Explanation of symbols

1, 2 Substrate 3 Image display medium (particle group or powder fluid)
3W White particle group 3B Black particle group 4 Bulkhead 5, 6 Electrode 11, 12 Insulating film 13 Dummy electrode 14 Connection pattern 15 Anodizing liquid 16 Platinum plate 17 Connection line 18 Alligator clip 21 Container 22 Electrolytic solution 23 Anode plate 24 Cathode plate 25 Power supply

Claims (4)

  An image display medium is sealed between two substrates, at least one of which is transparent, and an image is applied by moving the image display medium by applying an electric field to the image display medium by applying a voltage to an electrode provided on the substrate. An image display panel, wherein a metal oxide insulating film formed by an anodic oxidation method is formed on a metal electrode.   2. The image display panel according to claim 1, wherein an insulating film of a metal oxide is formed on an electrode other than the metal electrode by a method other than the anodic oxidation method.   The image display panel according to claim 1, wherein the image display medium is a particle group or a powder fluid.   4. The method for manufacturing an image display panel according to claim 1, wherein all the metal electrodes on the substrate and the dummy electrodes provided at the end portions of the substrate are connected, and the dummy is provided in the anodizing solution. While immersing the substrate with only the electrode out of the anodizing solution, immersing the platinum plate, applying the voltage with the dummy electrode as the positive electrode and the platinum plate as the negative electrode, anodizing the metal electrode A method for producing an image display panel, wherein a metal oxide insulating film is formed by a method.

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