JP2006023541A - Panel for image display, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a panel for image display, by which no dropping off of an image display medium from a partition wall defining a cell occurs, and as a result uneven distribution of the image display medium is prevented, and an image with stable image quality is obtained, and a method for manufacturing the same. <P>SOLUTION: In the panel for image display, displaying an image by forming a plurality of cells partitioned with partition walls 4 between opposing two sheets of substrates 1, 2, of which at least one is transparent, sealing the image display medium 3 in the cells, and applying an electric field to the image display medium and transferring the image display medium, the partition wall mounted for the purpose of defining the cells has a structure formed by placing the partition walls arranged on both of the two substrates opposite to each other and joining them to each other. Preferably, in the structure of the partition walls 4, an intersection point 4-1 of the partition wall in each of the substrates is constructed so as to be higher than other parts 4-2 of the partition wall, the intersection points of the partition walls arranged on both of the two substrates are placed opposite to each other and joined to each other, and further, the distance between the substrates is determined by the height of the partition wall in this part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention forms a plurality of cells partitioned by partition walls between two opposing substrates at least one of which is transparent, encloses an image display medium in the cells, and applies an electric field to the image display medium. The present invention relates to an image display panel that displays an image by moving an image display medium, 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, a cell isolated from each other by a partition is formed between two opposing substrates, at least one of which is transparent, and an image display medium is sealed in the cell. 2. Description of the Related Art An image display panel that displays an image by applying an electric field to an image display medium and moving 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 image display panel having the above-described configuration, usually, a partition is provided only on one substrate, and two substrates are joined by joining the top of the partition and the other substrate. At that time, the filled image display medium may come off from the gap between the substrate opposite to the side on which the partition wall has been provided in advance and the top of the partition wall, causing the image display medium to be unevenly distributed and stabilizing the image quality of the displayed image. There was a problem that hindered us. Further, in order to prevent the image display medium from coming off from the gap between the top of the partition wall and the substrate, the image display medium adheres to the adhesive that protrudes from the substrate in the cell when bonded with an adhesive or the like. There were also problems that made it difficult to move.

  The object of the present invention is to solve the above-mentioned problems, and to prevent the image display medium from coming off from the partition walls defining the cells. As a result, it is possible to prevent the image display medium from being unevenly distributed and obtain a stable image quality. An image display panel and a manufacturing method thereof are to be provided.

  The image display panel of the present invention forms a plurality of cells partitioned by partition walls between two opposing substrates, at least one of which is transparent, encloses the image display medium in the cells, and the electric field is applied to the image display medium. In the image display panel that displays the image by moving the image display medium, the partition walls provided to define the cells are bonded to each other with the partition walls provided on both of the two substrates facing each other. It has the structure which was made.

  As a suitable example of the image display panel of the present invention, the distance between the substrates is determined by the height of the partition walls provided on both of the two substrates, and the partition walls provided to define the cells are in each substrate. The intersection of the partition walls is made higher than the other part of the partition walls, the intersections of the partition walls provided on both of the two substrates are joined to face each other, and the distance between the substrates is determined by the height of the partition walls in this part. And the image display medium is a particle group or a powder fluid.

  The image display panel manufacturing method of the present invention is the image display panel manufacturing method having the above-described structure, in which partition walls are provided on both of the two substrates, and an adhesive is applied to the partition wall portions to be joined. The two substrates are joined by joining the portions to be joined of the partition walls facing each other.

  In the present invention, the partition provided to define the cell has a structure in which the partitions provided on both of the two substrates are opposed to each other, that is, the junction of the partitions is between the two substrates. As a result, it is possible to prevent the image display medium from coming off from the partition walls defining the cells. As a result, it is possible to prevent the image display medium from being unevenly distributed and to obtain an image with stable image quality.

  First, the basic configuration of the image display panel of the present invention will be described. In the image display panel of the present invention, an electric field is applied to two types of image display media (particle group or powder fluid) sealed between two opposing substrates and having different charging properties. Along 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 Coulomb force, and charged at a high potential toward the low potential side. The image display medium is attracted by the force of the electric field or the -ron force, and the image display medium is reciprocated by a change in the electric field direction due to the switching of the electric potential, 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, the force applied to the particles or powder fluid used as the image display medium is not only the force attracted by the Coulomb force between the particles or powder fluid, but also the image power, intermolecular force, liquid crosslinking force with the electrode or substrate. , Gravity and so on.

An example of the image display panel of the present invention will be described with reference to FIGS.
In the example shown in FIG. 1, two or more kinds of image display media 3 having different colors (here, white particles 3W and black particles 3B are shown) are applied to the substrate 1, 2, the black particles 3 </ b> B are visually recognized by the observer and black display is performed, or the white particles 3 </ b> W are visually recognized by the observer and white display is performed. A partition cell 4 is provided between the substrates 1 and 2 in a lattice shape, for example, to define a display cell.
In the example shown in FIG. 2, an image display medium 3 having two or more different colors (here, white particles 3 </ b> W and black particles 3 </ b> B) are provided between an electrode 5 provided on the substrate 1 and an electrode 6 provided on the substrate 2. Depending on the electric field generated by applying a voltage between them, the substrate is moved perpendicularly to the substrates 1 and 2 and the black particles 3B are visually recognized by the observer to display black, or the white particles 3W are observed by the observer. The white display is made visible. A partition cell 4 is provided between the substrates 1 and 2 in a lattice shape, for example, to define a display cell.
In the example shown in FIG. 3, according to the electric field generated by applying a voltage between the electrode 5 and the electrode 6 provided on the substrate 1, one kind of color particle 3 (here, white particle 3W). The white particles 3W are moved in the direction parallel to the substrates 1 and 2 and the white particles 3W are visually recognized by the observer, or the color of the electrode 6 or the substrate 1 is visually recognized by the observer. The color is displayed. A partition cell 4 is provided between the substrates 1 and 2 in a lattice shape, for example, to define a display cell.
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.

  The image display panel and the manufacturing method thereof according to the present invention are characterized in that a partition wall 4 provided to define a cell has a structure in which partition walls provided on both of two substrates 1 and 2 are joined to face each other. Further, as a more preferable example, the partition 4 provided to define the cell is configured such that the intersection of the partition is higher than the other part of the partition in each substrate, and the partition provided on both of the two substrates. It has a structure in which the intersections are opposed to each other and bonded, and the distance between the substrates is determined by the height of the partition walls in this part. Hereinafter, the present invention will be described focusing on the above-described preferred examples.

  4 (a) and 4 (b) are diagrams showing an example of the partition wall in the image display panel of the present invention, FIG. 4 (a) shows a plane of the partition wall, and FIG. 4 (b) shows FIG. The cross section along the AA line of FIG. In the example shown in FIGS. 4A and 4B, for convenience of explanation, an example of 2 × 2 cells is shown. However, in an actual image display panel, the panel is composed of a larger number of cells. In the example shown in FIGS. 4A and 4B, the partition wall 4 is composed of an intersection part 4-1 where the partition wall intersects and a wall part 4-2 other than the intersection part 4-1. And it is comprised so that the height of the intersection part 4-1 may become higher than the height of the other wall part 4-2. In this example, the top part of the intersection part 4-1 is used for joining. The partition walls 4 having the configuration shown in FIGS. 4A and 4B are provided on both the substrates 1 and 2.

  The shape of the partition wall 4 in the image display panel of the present invention is not particularly limited and can be appropriately selected according to the size of the panel or cell, but the following shape is preferable. First, from the restrictions on the strength and the area of the display screen, the width of the partition wall 4 is preferably 2 to 100 μm, and more preferably 3 to 50 μm. The length of each partition wall 4 (related to the cell size) is preferably 200 to 500 μm. 5-30 micrometers is preferable and, as for the length of the intersection part 4-1 of the partition 4, 5-20 micrometers is more preferable. If the length of the intersection portion 4-1 is smaller than 5 μm, there is a problem in the strength to secure the distance between the substrates 1 and 2 and support the substrates 1 and 2; This is not preferable because the displayed image display medium 3 cannot be reliably removed.

  As shown in FIG. 5, the display cell formed by the partition walls 4 is 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. And a mesh shape. 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. Here, examples of the method for forming the partition walls 4 include a screen printing method, a sand blast method, a photolithography method, and an additive method. Of these, the photolithography method using a resist film is preferably used. In any method, the present invention can be suitably used.

  FIGS. 6A and 6B are views for explaining an example of the method for manufacturing the image display panel of the present invention. First, as shown in FIG. 6A, partition walls 4 that define cells are provided on both substrates 1 and 2. At this time, when the intersection portion 4-1 of the partition wall 4 is configured to be higher than the other wall portions 4-2, and the intersection portion 4-1 is overlapped, the interval between the substrates 1 and 2 is a predetermined substrate. The partition 4 is configured so as to have an interval. Next, a predetermined image display medium 3 is filled in the cells defined by the partition walls 4 on the lower substrate 1. Thereafter, as shown in FIG. 6B, the intersection portion 4-1 of the partition wall 4 is overlapped and joined, whereby the image display panel of the present invention can be obtained.

  In the above-described example, when the image display medium 3 is filled, the image display medium 3 placed on the intersection portion 4-1 of the partition wall 4 can be reliably removed before the two substrates 1 and 2 are joined. The distance can be made constant according to the height of the intersection part 4-1 of the partition wall 4, and there is little gap on the mating surface of the intersection part 4-1 of the partition wall 4, thereby eliminating the omission of the image display medium 3. Can do. Further, in this structure, the partition wall 4 defining the cell has a gap at the wall portion 4-2 and is not completely closed, but the position of the gap is a position away from both the substrates 1 and 2. Therefore, the image display medium 3 that has been a problem in the past does not come off in the gap between the top of the partition wall and the substrate surface. The reason for this is not clear, but it is considered that this is caused by the difference between the gap at the surface of the substrates 1 and 2 that is the movement end point of the moved image display medium 3 and the gap at the intermediate point of movement. In order to remove the image display medium 3 placed on the top of the intersection portion 4-1 at the time of filling, a removal roller, a removal sheet, or a method of scraping with a plate is used. If the intersection portion 4-1 is high, the image display medium 3 can be removed reliably. The reason for this is not clear, but it is considered that there is a difference in stress acting between the removal member and the top of the intersection portion 4-1 during removal. It is important that the excess image display medium 3 is removed from the partition wall portion that becomes the bonding portion, and even if some image display medium 3 remains on the top of the partition wall that does not become the bonding portion, the distance between the substrates is not affected. It doesn't matter.

  FIGS. 7A to 7C are views for explaining another example of the method for manufacturing the image display panel of the present invention. In the example shown in FIGS. 7A to 7C, unlike the examples shown in FIGS. 6A and 6B, the relationship between the electrodes excluding the substrate and the partition walls is shown. First, as shown in FIG. 7A, a line electrode 5-1 is formed for each cell in the horizontal direction on the partition wall 4 (intersection portion 4-1 and wall portion 4-2) on the substrate 2 side on the back surface. As shown in FIG. 7B, the electrode 5 on the substrate 2 side and the partition wall 4 are prepared, and the line electrode 5 is provided on the partition wall 4 (intersection portion 4-1 and wall portion 4-2) on the front substrate 1 side as shown in FIG. A transparent line electrode 5-2 is formed for each cell in the vertical direction, which is 90 degrees different from -1, and an electrode 5 and a partition wall 4 on the front substrate 1 side are prepared. Then, as shown in FIG. 7A, after the white particle 3W and the black particle 3B are filled in the cell on the back substrate 2 side, the intersection portion 4- of the partition wall 4 is formed as shown in FIG. 7C. By overlapping and joining one another, the image display panel of the present invention can be obtained. The image display medium 3 (particles or powdered fluid) may be filled on the front substrate side or on the back substrate side. Further, both the substrate sides may be filled.

  FIG. 8 is a view for explaining another example of the image display panel of the present invention. In each of the above examples, a rectangular cell is illustrated, but a hexagonal honeycomb-shaped cell can also be used as shown in FIG. Also in this case, by forming the partition wall 4 from the intersection portion 4-1 and the other wall portion 4-2, the image display panel of the present invention can be obtained in the same manner as in the above-described example.

  Hereafter, each member which comprises the image display panel of this invention is demonstrated.

  As for the substrate, at least one substrate is the transparent substrate 1 from which the color of the image display medium can be confirmed from the outside of the panel, and a material having high visible light transmittance and good heat resistance is preferable. The substrate 2 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 substrate is preferably 2 to 5000 μm, more preferably 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the uniformity of the distance between the substrates, and if it is thicker than 5000 μm, it will be a thin image display panel. Is inconvenient.

  Electrode forming materials for electrodes provided as necessary include metals such as aluminum, silver, nickel, copper, and gold, conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide, polyaniline , Conductive polymers such as polypyrrole and polythiophene are exemplified, and are appropriately selected and used. Since the polymer material is etched by oxygen RIE, care must be taken when using it as an electrode material. 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. The electrode provided on the viewing side substrate needs to be transparent, but the electrode provided on the back side substrate does not need to be transparent. In any case, the above-mentioned material that is conductive and capable of pattern formation can be suitably 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 and thickness of the electrode provided on the back side substrate are the same as those of the electrode provided on the view side substrate 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, liquid crystal is defined as an intermediate phase between a liquid and a solid, and has fluidity that is a characteristic of liquid and anisotropy (optical properties) that is a characteristic of 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 a fluid (ordinary) Company: Encyclopedia). As described above, the gas-solid fluidized bed body and the liquid-solid fluid are in a state of using a gas or liquid flow. 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.

  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 50 μm, and are preferably 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 image display medium naturally depends on the measurement conditions, but the charge amount of the image display medium in the image display panel is almost the initial charge amount, the contact with the partition wall, the contact with the substrate, and the charge decay with the elapsed time. In particular, it was found that the saturation value of the charging behavior of the image display medium is the dominant factor.

Furthermore, in the present invention, it is important to manage the gas in the gap surrounding the image display medium between the substrates, which contributes to improved display stability. 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.
In FIG. 1 to FIG. 3, this void portion is an area occupied by the electrodes 5 and 6, the image display medium (particle group or powder fluid 3), and an area occupied by the partition wall 4 from the portion sandwiched between the opposing substrates 1 and 2. The part (if present) and the gas part in contact with the so-called image display medium, excluding the device seal part, shall be indicated.
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 apparatus so that the humidity is maintained. For example, the image display medium is filled and the substrate is assembled in a predetermined humidity environment. It is important to apply a sealing material and a sealing method to prevent the above.

The distance between the substrates in the image display panel of the present invention is not limited as long as the image display medium can be moved and the contrast can be maintained, but is usually adjusted to 10 to 500 μm, preferably 10 to 200 μm.
The volume occupation ratio of the image display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. If it exceeds 70%, the movement of the image display medium is hindered. If it is less than 5%, the contrast tends to be unclear.

  Hereinafter, the present invention and a comparative example will be shown to specifically describe the present invention, but the present invention is not limited to the following. In addition, the panel for image display of an Example and a comparative example evaluated what produced by the following method according to the following reference | standard.

“Production of image display panels”
First, a transparent glass substrate (7 cm × 7 cm □) with an ITO electrode was prepared as a front substrate and a rear substrate, and partition walls were formed by ribs having a height of 50 μm.
The rib is formed by the following procedure.
The paste is prepared by preparing glass powder obtained by melting, cooling and grinding SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , ZnO as inorganic powder, and thermosetting epoxy resin as resin. A paste adjusted to a viscosity of 12000 cps with a solvent was prepared. Next, the paste was applied on the entire surface of the substrate, heated and cured at 150 ° C., and this coating to curing was repeated to adjust the thickness (corresponding to the height of the partition wall) to 50 μm. Next, a dry photoresist was attached, and a mask was formed so that a desired partition wall pattern was formed by exposure to etching. Next, excess portions were removed by sandblasting so as to obtain a predetermined partition wall shape, and a partition wall having a desired shape was formed.

  Next, two types of particle groups (particle group A and particle group B) having different colors and charging characteristics are prepared. The substrate on which the partition walls are formed is transferred into a dry container having a humidity of 40% RH or less. First, the particle group A is dispersed as a first particle group in the container from a nozzle provided in the upper part of the container. Particle group A was filled by spraying into cells on a substrate placed underneath. Subsequently, the particle group B is dispersed into the container from another nozzle provided in the upper part of the container as the second particle group, and the cell on the substrate placed in the lower part of the container (the particle group A is already filled). The particle group A was overlaid and packed by spraying. The packing arrangement amount of the particle group A and the particle group B was set to the same volume amount, and the volume occupancy ratio of both particle groups with respect to the space between the substrates formed by bonding the two substrates was adjusted to 26 vol%. Subsequently, an extra particle group placed on the top of the partition wall was removed by rolling the removal roller on the substrate. Next, the other substrate is superimposed on the substrate in which the particle group is filled and arranged in the cell, and the outer peripheral portion around the substrate is bonded and sealed with an epoxy adhesive to enclose the particle group, and an image display panel Was made.

"Evaluation of display function"
Black-white display was repeated by applying a voltage of 250 V to the display device incorporating the manufactured display panel and inverting the potential. For the evaluation of the display function, the uniformity of the image display medium (particle group) in the cell near the partition wall intersection was examined by observing the display surface during white display and black display with an optical microscope.

"Image display medium"
In Examples and Comparative Examples, a black and white two-color particle group (particle group A, particle group B) having different charging characteristics was used as an image display medium.
Particle group A consists of acrylic urethane resin EAU53B (manufactured by Asia Industry Co., Ltd.) / IPDI crosslinking agent Excel Hardener HX (manufactured by Asia Industry Co., Ltd.), 4 parts by weight of carbon black (MA100 Mitsubishi Chemical Corporation), charge control. 2 parts by weight of the agent Bontron N07 (Orient Chemical Co., Ltd.) was added, kneaded, pulverized with a jet mill, and mechanical impact force was applied using a hybridizer device (Nara Machinery Co., Ltd.). In addition, classification was made after making it approximately spherical. The produced particle group A was an approximately spherical and negatively charged black particle group having an average particle diameter of 9.1 μm.

  Particle group B was prepared by dissolving 0.5 parts by weight of AIBN (azobisisobutyronitrile) in 80 parts by weight of tertiary butyl methacrylate monomer and 20 parts by weight of 2- (diethylamino) ethyl methacrylate. The liquid obtained by dispersing 20 parts by weight of titanium oxide made lipophilic by treatment with an agent is suspended and polymerized in an aqueous solution of 0.5% surfactant (sodium lauryl sulfate), filtered, dried. Then, it was prepared using a classifier (MDS-2: Nippon Numatic Industries). The produced particle group B is a positively charged spherical white particle having an average particle diameter of 8.5 μm.

<Example 1>
For display using a front substrate and a rear substrate on which the partition walls are formed so that the cells are square and arranged in a lattice pattern, and the height of the portion where the partition wall intersects and the other position is the same 50 μm A panel was prepared according to the procedure described above, and the display function was evaluated. The results are shown in Table 1.

<Example 2>
The display panel is formed by using the front substrate and the rear substrate in which the partition walls are formed so that the cells have a hexagonal honeycomb arrangement and the height of the intersection of the partition walls and the other position is the same 50 μm. The display function was evaluated. The results are shown in Table 1.

<Example 3>
A front substrate on which the partition is formed so that the cell has a square and lattice arrangement, the height of the intersection of the partition is 50 μm, and the height of the other position of the partition is lower than 50 μm Using the back substrate, a display panel was produced according to the procedure described above, and the display function was evaluated. The results are shown in Table 1.

<Example 4>
Using the front substrate and the rear substrate on which the partition walls are formed so that the cells are square and arranged in a lattice pattern, and the heights of the portions that are the intersections of the partition walls and the other positions are the same 50 μm, the intersections of the partition walls A display panel was produced in the same manner as described above except that an epoxy adhesive was provided on the part and the substrate was bonded together, and the display function was evaluated. The results are shown in Table 1.

<Example 5>
A front substrate on which the partition is formed so that the cell has a square and lattice arrangement, the height of the intersection of the partition is 50 μm, and the height of the other position of the partition is lower than 50 μm A display panel was produced in the same manner as described above, except that a back substrate was used and an epoxy adhesive was provided at the intersection of the partition walls to bond the substrates, and the display function was evaluated. The results are shown in Table 1.

<Comparative Example 1>
Partitions are formed only on the front substrate so that the cells are square and in a lattice arrangement, and the height of the other positions and the intersections of the partitions are the same 100 μm, and the partition is formed on the rear substrate. A display panel was produced by using the non-formed one according to the procedure described above, and the display function was evaluated. The results are shown in Table 1.

<Comparative example 2>
Partitions are formed only on the front substrate so that the cells are square and in a lattice arrangement, and the height of the other positions and the intersections of the partitions are the same 100 μm, and the partition is formed on the rear substrate. A display panel was produced in the same manner as described above, except that an unformed one was used, and an epoxy adhesive was provided at the junction of the partition walls to bond the substrates together. The display function was evaluated. The results are shown in Table 1.

<Comparative Example 3>
Using a front substrate and a rear substrate on which the partition walls are formed so that the cells have a square and lattice arrangement, and the height of the intersections and the other positions are the same 50 μm, the partition walls are joined. A display panel was produced in the same manner as described above except that an epoxy adhesive was provided on the part and the substrate was bonded together, and the display function was evaluated. The results are shown in Table 1.

  From the results in Table 1, the following can be understood. First, in Examples 1 to 5 where the partition wall bonding surface in the cell is located away from the substrate surface, the particles do not escape from the cell, and a good state is maintained even after 100,000 times from the initial stage. On the other hand, in Comparative Example 1 and Comparative Example 2 in which the partition wall bonding surface is on the substrate surface, there is no problem in the state of particles in the cell at the initial stage, but the particles are unevenly distributed after 100,000 times. It is inferred that the particles gradually escape from the cell and move to other cells.

  Further, in Examples 4 and 5 in which the adhesive is provided only at the intersection of the partition walls, the particles are not adhered to the adhesive-applied portion even during repeated reversal display, and a good cell even after 100,000 times from the beginning. In Comparative Example 2 and Comparative Example 3 in which an adhesive was provided on the entire surface of the partition wall, there was a situation where particles adhered to the adhesive application portion during repeated reversal display. The particle state in the cell was poor.

  Furthermore, in Example 3 and Example 5 in which the junction part of the partition wall is slightly higher than other positions, unnecessary particles deposited on the top of the partition wall, which is a joint part, are removed when the particles to be filled are dispersed. It is easy to do, and the man-hour until the subsequent bonding of the substrates is reduced.

  The image display panel according to the present invention includes display units for mobile devices such as notebook computers, PDAs, mobile phones, and handy terminals, electronic papers such as electronic books and electronic newspapers, bulletin boards such as signboards, posters, and blackboards, calculators, and home appliances. 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.

It is a figure which shows an example of the panel for image display used as the object of this invention. It is a figure which shows the other example of the image display panel used as the object of this invention. It is a figure which shows the further another example of the image display panel used as the object of this invention. (A), (b) is a figure which shows an example of the partition in the image display panel of this invention, respectively. It is a figure which shows an example of the shape of the partition in the image display panel of this invention. (A), (b) is a figure for demonstrating an example of the manufacturing method of the image display panel of this invention, respectively. (A)-(c) is a figure for demonstrating the other example of the manufacturing method of the image display panel of this invention, respectively. It is a figure for demonstrating the other example of the image display panel of this invention.

Explanation of symbols

1, 2 Substrate 3 Image display medium (particle or powder fluid)
3W white particles (white powder fluid)
3B Black particles (black powder fluid)
4 Partition 4-1 Intersection part 4-2 Wall part 5, 6 electrode 5-1 5-2 Line electrode

Claims (5)

  An image display medium is formed by forming a plurality of cells partitioned by partition walls between two opposing substrates at least one of which is transparent, enclosing the image display medium in the cells, and applying an electric field to the image display medium In the image display panel for displaying an image by moving the partition, the partition provided to define the cell has a structure in which the partitions provided on both of the two substrates are joined to face each other. Image display panel.   2. The image display panel according to claim 1, wherein the distance between the substrates is determined by the height of the partition walls provided on both of the two substrates.   Partition walls provided to define the cells are configured such that the intersections of the partition walls are higher than the other portions of the partition walls in each substrate, the intersections of the partition walls provided on both of the two substrates are bonded to each other, and 3. The image display panel according to claim 1, wherein the image display panel has a structure in which the distance between the substrates is determined by the height of the partition walls in this portion.   The image display panel according to claim 1, wherein the image display medium is a particle group or a powder fluid.   The method for manufacturing an image display panel according to any one of claims 1 to 4, wherein a partition wall is provided on both of the two substrates, an adhesive is applied to a partition wall portion to be bonded, and the partition wall is bonded. A method for manufacturing an image display panel, wherein two substrates are joined by joining the power portions facing each other.

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