JP4671642B2 - Image display panel and manufacturing method thereof - Google Patents

Description

  The present invention forms a plurality of cells partitioned by a partition between two opposing substrates at least one of which is transparent, encapsulates 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 method for manufacturing the same.

  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. In addition, 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 that the stability of repeated image display is lacking. ing. 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. In the case of these dry image display medium moving display systems, the image display medium is sealed between the substrates of the image display panel, but the image display medium is prevented from becoming unevenly distributed as the movement is repeated. For this purpose, a method of enclosing an image display medium in a small room (cell) surrounded by a partition wall is used.
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 these image display panels, since the image display medium is filled in the cells formed by the partition walls before the two substrates are overlapped, even a little extra is provided on the tops of the partition walls that become the joining portions when the two substrates are stacked. If the image display medium adheres to the substrate, the distance between the substrates becomes non-uniform and adversely affects the quality of the displayed image. Therefore, it is essential to remove the image display medium before stacking the substrates. It has been a problem in productivity as a process.

  The object of the present invention is to eliminate the above-mentioned problems, eliminate the need for a step of removing the image display medium, maintain a constant distance between the substrates after superposition, high productivity, low cost and image quality. It is an object of the present invention to provide an image display panel and a method for manufacturing the same.

The image display panel of the present invention forms a plurality of cells partitioned by a partition wall between two opposing substrates at least one of which is transparent, and has at least different optical reflectivity and charging characteristics in the cell. An image display panel for enclosing two types of image display media and moving the image display medium to display an image by applying an electric field to the image display medium, wherein the cell enclosing the image display medium is defined. The barrier ribs provided for the two substrates are provided in a line shape between the electrodes of the comb-shaped line electrodes provided on both of the two substrates, and the barrier ribs and combs provided on both of the two substrates. The mold line-shaped electrodes are formed so as to face each other at right angles, and at least one of the partition walls provided on both of the two substrates is lower than the height of the other part of the partition wall at the joint portion. The distance between the substrates is determined by the sum of the partition wall heights of the partition wall portions joined to each other, and the total height of the partition walls of the partition wall portions joined to each other is is characterized in Rukoto exceed the height of both the partition walls provided on both sides.

An image Preferred examples of the display panel of the present invention, it images the display medium is particles or liquid powders, there is.

The method for manufacturing an image display panel according to the present invention is a method for manufacturing an image display panel, wherein a line shape is formed between electrodes of comb-shaped line electrodes provided on both of the two substrates. After the image display medium is filled in either one of the substrates, at least one of which is provided with a partition wall having a recess that is lower than the height of the other part of the partition wall at a portion where the partition walls are joined to each other, The distance between the substrates is determined by the sum of the heights of the partition walls that are joined to each other by overlapping the line-shaped partition walls and the comb-shaped line-shaped electrodes provided on both of the substrates so as to be orthogonal to each other. it is intended to, and total bulkhead height of the partition portion joining this together is characterized in that it has a so that exceed the height of both the partition walls provided on both substrates.

As a preferred example of the method for manufacturing an image display panel of the present invention, at least either of the partition lines provided in a line shape between the electrodes of the comb-shaped line electrodes provided on both of the two substrates. as a method for filling the image display medium or on one substrate side, be done by pushing the image display medium using the blade along the bulkhead line direction, there is.

  In the present invention, when providing the partition walls defining the cells on the substrates, both the substrates are provided with line-shaped partition walls, and the partition wall height of the joint portion when the substrates are overlapped is the inter-substrate distance. The image display medium can be filled more easily than in the case where the image display medium is filled in the cells on the substrate having the partition walls that form completely independent cells. Therefore, since the image display medium can be filled without adhering to the top of the partition wall, the process of removing the image display medium is unnecessary, and the distance between the substrates after overlapping is performed. In addition, it is possible to obtain an image display panel that is kept constant, has high productivity, is inexpensive, and has excellent image quality, and a manufacturing method thereof.

  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 a chargeable image display medium (particle group or powder fluid) sealed between two opposing substrates. The charged image display medium is attracted by the electric field force or Coulomb force along the applied electric field direction, and the image display medium is reciprocated by the change in 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, 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 FIG. In the example shown in FIG. 1, an electrode 5 provided on a substrate 1 and an electrode provided on a substrate 2 are provided with an image display medium 3 composed of at least one kind of particles (here, white particles 3W and black particles 3B are shown). The black particles 3B are moved vertically to the substrates 1 and 2 according to the electric field generated by applying a voltage between the black particles 3 and the black particles 3B are visually recognized by the observer, or the white particles 3W are displayed. Is displayed in white by the observer. A partition 4 is provided between the substrates 1 and 2 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.

Figure 2 (a) ~ (c) is a plan view for explaining an example of a substrate constituting the panel their respective images displayed, a front view and a side view. In the example shown in FIGS. 2A to 2C, the comb-shaped line electrode 5 on one substrate 1 is shown as an example, but the comb-shaped line electrode 6 on the other substrate 2 is also the same. It has the composition of. In the example shown in FIGS. 2A to 2C, the feature of the present invention is that a line-shaped partition wall 4 is provided between the electrodes of the comb-shaped line-shaped electrode 5 so that there is no gap with the substrate 1. It is a point. Here, the relationship between the distance L between the electrodes and the width D of the partition 4 is L ≧ D.

FIG. 3 (a), it is a diagram for explaining an example of (b) is, respectively it images the display panel. As shown in FIG. 3 (a), the substrate 1 in which the partition walls 4 are provided in a line shape between the electrodes of the line electrodes 5, and the partition walls 4 are lined between the electrodes of the line electrodes 6 and the electrodes. As shown in FIG. 3B, the image display panel of the present invention is obtained by superimposing the electrodes 2 and 6 and the partition walls 4 so as to be orthogonal to each other. In this example, the distance between the substrates 1 and 2 is determined by the total height of the partition walls that become the joint portions of the partition walls 4 provided on both of the two substrates 1 and 2.

  4A to 4C are a plan view, a front view, and a side view, respectively, for explaining another example of a substrate constituting the image display panel of the present invention. In the example shown in FIGS. 4A to 4C, when the partition 4 and the partition 4 are joined to each other in addition to the line-shaped partition 4 provided between the electrodes of the line electrode 5. A recess 11 that is lower than the height of the other part of the partition wall 4 is formed in the part to be joined together. Therefore, as shown in FIGS. 5 (a) and 5 (b), when the concave portions 11 are joined to each other and the substrates 1 and 2 are joined, the total of the partition wall heights of the partition wall portions to be joined to each other, The distance between the two partitions is determined, and the total height of the partition walls joined to each other is equal to or greater than the height of both partition walls 4 provided on both the substrates 1 and 2.

In the image display panel of the present invention configured as described above, the cells filling the image display medium 3 are not completely sealed, but uneven distribution of the image display medium 3 can be prevented. The reason will be described with reference to FIGS. 6 (a) and 6 (b) and FIGS. 7 (a) and 7 (b).

First, FIG. 6 (a), the (b), the Example partition wall 4 is superimposed two substrates 1 and 2 which are formed in parallel to the line electrodes 5 and 6, the comb-type electrode 5, 6, since the potential is the same at the same electrode position, the image display medium 3 on the electrode 5 moves toward the electrode 6 on the facing substrate side having a different potential as indicated by A, but exceeds the partition wall 4 as indicated by B and C. Since it does not move, uneven distribution of the image display medium 3 does not occur even if it is repeatedly moved. On the other hand, FIG. 7 (a), as shown, in the example the partition walls 4 are superimposed two substrates 1 and 2 which are formed to cross the line electrodes 5 and 6, on the substrate 5 (b) The image display medium 3 moves toward the electrode 6 on the facing substrate side as in A, but the image display medium 3 positioned at the end on the electrode 5 includes B and C shown in FIG. When the image display medium 3 is moved repeatedly by moving to the adjacent electrode 5 as shown in FIG. 7 or moving to the electrode 6 in another cell on the facing substrate side as shown in FIG. Uneven distribution occurs. In particular, when there is a potential difference with an adjacent electrode, the image display medium 3 shown as B and C in FIG.

  Next, the state in which the image display medium is filled in the image display panel of the present invention, and the state of monochrome display when the white particle group 3W and the black particle group 3B are used as the image display medium 3 will be described.

Figure Figure 8 (a) ~ (c) and FIG. 9 (a) ~ (c) are shown respectively, in the substrate used for the images display panel, a state filled with white particles 3W as an image display medium 3 It is. In the example shown in FIGS. 8A to 8C, an example in which the parallel partition walls 4 are provided between the electrodes of the comb electrode 5 is shown, and the white particle group 3 </ b> W is placed in the cell defined by the partition walls 4. It shows a state in which the filler is removed and the excessive white particle group 3W on the partition walls 4 is removed. In the example of the present invention shown in FIGS. 9 (a) to 9 (c), an example in which parallel line-shaped partition walls 4 having recesses 11 are provided between the electrodes of the comb electrode 5 is shown, and the white particle group 3 </ b> W is defined by the partition walls 4. It shows a state in which the formed cell is filled and an excessive white particle group 3W on the partition wall is removed.

Figure 10 (a), (b) and FIG. 11 (a), the in (b), respectively, images display panel used as an image display medium 3 and a white particle group 3W and the black particles 3B, the transparent substrate It is a figure which shows a mode that the black display image on a center line electrode is observed from the side. Here, FIGS. 10A and 10B show an example in which the line-shaped partition walls 4 are simply overlapped, and FIGS. 11A and 11B show the line-shaped partition walls 4 having the recesses 11 between the recesses 11. The example of this invention which was made to fit and overlap | superposed is shown. Figure 12 (a), (b) and FIG. 13 (a), (b), respectively, as the image display media 3 in images display panel using the white particles 3W and black particles 3B, the transparent substrate It is a figure which shows a mode that the state of a monochrome display image is observed from the side. Here, FIG. 12A and FIG. 13A each show a black display state, and FIG. 12B and FIG. 13B each show a white display state. 12A and 12B show examples of black and white display when the line-shaped partition walls 4 are simply overlapped, and FIGS. 13A and 13B show the line-shaped partition walls 4 having the recesses 11. An example of the present invention in which the concave portions 11 are fitted and overlapped is shown.

Next, the filling method of the image display medium in the method of manufacturing the images display panel will be described with reference to FIG. 14 (a) ~ (d) and FIG. 15 (a) ~ (d) .

  FIGS. 14A to 14D are diagrams each showing an example in which the white particle group 3W as the image display medium 3 is filled in the substrate 1 in which the line-shaped partition walls 4 are provided between the electrodes 5. First, as shown in FIGS. 14A and 14B, the substrate 1 is set in the holder 21. The surface of the holder 21 is set to be at the same position as the surface of the partition wall 4. Then, by pushing the white particle group 3W set on the holder 21 with the blade 22, the white particle group 3W can be filled between the partition walls 4 as shown in FIGS. 14 (c) and 14 (d). In the example shown in FIGS. 14A to 14D, the white particle group 3 </ b> W can be filled without adhering to the top of the partition wall, which is a joint portion between the partition walls, which is necessary in the conventional filling process. The image display medium removing step at the top of the partition wall can be eliminated.

  FIGS. 15A to 15D are diagrams showing examples in which the white particle group 3W is filled in the substrate 1 in which the line-shaped partition walls 4 having the recesses 11 are provided between the electrodes 5. Similarly to the example shown in FIGS. 14A to 14D, first, the substrate 1 is set in the holder 21 as shown in FIGS. 15A and 15B. The surface of the holder 21 is set to be at the same position as the surface of the partition wall 4. Then, by pushing the white particle group 3W set on the holder 21 with the blade 22, the white particle group 3W can be filled between the partition walls 4 as shown in FIGS. 15 (c) and 15 (d). In the example shown in FIGS. 15A to 15D as well, the white particle group 3W adheres to the tops of the concave portions of the partition walls, which are the joint portions of the partition walls, as in the examples shown in FIGS. 14A to 14D. Thus, the image display medium removing process at the top of the partition wall, which is necessary in the conventional filling process, can be eliminated.

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

  For the partition wall 4 of the present invention, it is important to form the partition wall on both the front substrate and the back substrate in a line shape between the electrodes of the comb-shaped line electrode provided on the substrate. The height and width are appropriately set appropriately depending on the type of the image display medium involved in the display, and are not generally limited. However, the width of the partition wall is 2 to 100 μm, preferably 3 to 50 μm, and the height of the partition wall is 10 to 500 μm, preferably Is adjusted to 10 to 200 μm. The display cells formed by superimposing the line-shaped partition walls provided on both the front substrate and the rear substrate so as to be orthogonal to each other are square and have a lattice arrangement. . The partition shape need not be a straight line as long as it is a line shape, and may be a wavy line shape or a zigzag line shape. In this case, the display cells formed by superimposing the substrates are substantially square and have a lattice arrangement. 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 formed by the partition wall width) as small as possible, and the sharpness of the image display is increased.

  Regarding the substrate, at least one substrate (front substrate) is the transparent substrate 2 from which the color of the image display medium can be confirmed from the outside of the display panel, and a material having high visible light transmittance and good heat resistance is suitable. . The substrate 1 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 from 2 to 5000 μm, more preferably from 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the uniform spacing between the substrates, and if it is thicker than 5000 μm, it will be mounted on a thin image display device. There are inconveniences when using a display panel.

  For the comb-shaped line electrode provided on the substrate, the electrode 6 provided on the side of the front substrate 2 that is on the viewing side and needs to be transparent is formed of a conductive material that is transparent and can be patterned. Aluminum, silver, nickel Transparent from metals such as copper and gold, conductive metal oxides such as ITO, indium oxide, conductive tin oxide and conductive zinc oxide, conductive polymers such as polyaniline, polypyrrole and polythiophene, It is appropriately selected and used. 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. A method of applying 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 and thickness of the electrode 5 provided on the back substrate 1 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, 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 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 yellow lead, 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 yellow lead, 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 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 expressing 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 diameter 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 becomes 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.
In FIG. 1, the void portion refers to the portion occupied by the electrodes 5 and 6, the image display medium (particle group or powdered fluid 3), the portion occupied by the partition wall 4 (the non-filled portion). A portion where a partition wall defining a complete cell is present) and a gas portion in contact with a so-called image display medium excluding an apparatus 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 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 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.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, reference examples , and comparative examples according to the present invention, but the present invention is not limited to the following. The image display panels of Examples , Reference Examples and Comparative Examples were evaluated by the following methods according to the following criteria.

"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), IPDI crosslinker Excel Hardener HX (manufactured by Asia), 4 parts by weight of carbon black (MA100 Mitsubishi Chemical), 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.

“Production of image display panels”
First, transparent glass substrates (7 cm × 7 cm □) with ITO comb electrodes were prepared as a front substrate and a back substrate, and partition walls (ribs) were formed on each as follows. A dry film photoresist NIT250 made by Nichigo Morton Co., Ltd., which is a photosensitive film, is laminated on a glass with ITO, and by exposure and development, linear line partition walls and lattice partition walls with desired lines 30 μm, spaces 320 μm, pitch 350 μm are formed. did. The height was 50 μm, but a 100 μm one was also prepared as desired. With respect to the barrier ribs having the concave portions of the barrier rib portions that become the bonding portions when the substrates are overlapped with each other, the portion to be bonded is scraped using a wet blasting method so as to have a desired barrier rib shape and barrier rib concave portion height.

  Next, two types of particle groups (particle group A and particle group B) having different colors and charging characteristics were filled between the partition walls. First, the particle group A was placed on the side of the substrate on which the partition walls were formed as the first particle group, and was filled in the cells between the partition walls on the substrate by being pushed in the partition line direction using a blade. Subsequently, the particle group B was used as the second particle group in the same manner as described above to fill the particle group A in the cells (already filled with the particle group A) between the partition walls on the substrate. The packing arrangement amount of the particle group A and the particle group B was set to the same volume amount, and the volume occupation ratio of both particle groups with respect to the space between the substrates formed by bonding the two substrates was adjusted to 25 vol%. 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 image display panel"
The uniformity of the distance between the substrates of the produced image display panel was confirmed by measuring the thickness of the image display panel at five points including the four corners and the center. In addition, by applying a voltage of 250 V to the display device incorporating the manufactured display panel and inverting the potential, black to white display is repeated 10,000 times, at the time of white display after 10,000 times and at the time of black display The display surface was observed with an optical microscope to examine the uniformity of the image display medium (particle group) in the cell.

< Reference Example 1>
A display panel was manufactured and evaluated by the above-described procedure using two substrates, both of which are comb-shaped electrodes and a partition wall having a uniform height (50 μm) formed between the electrodes. . The results are shown in Table 1.

<Example 1 >
As the two substrates, one having a comb-shaped electrode and a partition wall having a uniform height (50 μm) is used, and the other is a uniform electrode between the electrodes. A display panel was manufactured and evaluated by the above-described procedure using a partition wall having a height (50 μm) and a portion where the portions to be joined to each other became a concave portion having a height of 25 μm. The results are shown in Table 1.

< Reference Example 2>
As the two substrates, both of which are comb-shaped electrodes having a uniform height (50 μm) between the electrodes and a partition wall in which a portion to be bonded to each other is a recess of 25 μm in height, A display panel was prepared and evaluated according to the procedure described above. The results are shown in Table 1.

<Reference Example 3 >
Using two substrates, both of which are comb-shaped electrodes and a partition wall having a uniform height (50 μm) formed between them, the particle group A is filled into one substrate. A display panel was prepared and evaluated in the same manner as in Example 1 except that the other group of substrates was filled with the particle group B, and each of the substrates was filled in another substrate and then overlapped. The results are shown in Table 1.

< Reference Example 4 >
As the two substrates, both of which are comb-shaped electrodes having a uniform height (50 μm) between the electrodes and a partition wall in which a portion to be bonded to each other is a recess of 25 μm in height, The same procedure as in Example 3 except that the filling of the particle group A is performed on one substrate, the filling of the particle group B is performed on the other substrate, and the other substrates are filled and then overlapped. A display panel was prepared and evaluated. The results are shown in Table 1.

<Comparative Example 1>
The same procedure as in Example 1 was used except that two substrates were used in which a grid-like partition wall defining a rectangular cell having a uniform height (50 μm) was formed on a comb-shaped electrode. A display panel was prepared and evaluated. The results are shown in Table 1.

<Comparative Example 2>
As the two substrates, one is formed by forming a grid-like partition that defines a rectangular cell having a uniform height (100 μm) on the interdigital electrode, and the other is formed by a partition on the interdigital electrode. A display panel was prepared and evaluated in the same procedure as in Example 1 except that the one not used was used. The results are shown in Table 1.

<Comparative Example 3>
Displayed in the same procedure as in Example 1 except that two substrates were used, both of which were comb-shaped electrodes and a line-shaped partition wall having a uniform height (50 μm) formed across the electrodes. Panels were prepared and evaluated. The results are shown in Table 1.

<Comparative example 4>
A display panel similar to that in Example 1 was prepared and evaluated except that the packing of the particle group A and the particle group B was performed by sequentially spraying each particle group from a nozzle above the substrate. The results are shown in Table 1.

  From the results of Table 1, Examples 1 to 5 in which line-shaped partition walls are formed between the electrodes are compared to Comparative Examples 1 to 4 that are different from the above-described Examples in terms of the shape and position of the partition walls, and to the top of the partition walls. It can be seen that there is no adhesion of the image display medium, the distance between the substrates is uniform, and the uniformity of the display image is good.

  In the above-described example, the dry image display panel in which the image display medium is moved in a gas such as air by an electric field has been described. However, a wet image in which the electrophoretic particles in the dispersion medium are moved by an electric field. The present invention can also be applied to a display panel. In the above-described example, the partition walls are provided between all the electrodes, but the partition walls can be provided by thinning out every other electrode.

  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 image display panel of this invention. (A) ~ (c) is a plan view for explaining an example of a substrate constituting the panel their respective images displayed, a front view and a side view. (A), (b) is a diagram for explaining an example of a substrate of the, respectively that images display panel. (A)-(c) is the top view, front view, and side view for demonstrating an example of the board | substrate which respectively comprises the image display panel of this invention. (A), (b) is a figure for demonstrating an example of the board | substrate which respectively comprises the image display panel of this invention. (A), it is a diagram for describing (b) is an example of uneven distribution of the image display medium in images display panel. (A), it is a diagram for describing (b) is another example of uneven distribution of the image display medium in images display panel. (A) ~ (c) is a diagram showing a state filled with the display medium in one example of a substrate used for, respectively therewith images display panel. (A)-(c) is a figure which shows the state which filled the image display medium in an example of the board | substrate used for the image display panel of this invention, respectively. (A), a diagram showing a state of observing a black display image in an example of (b) is, respectively it images the display panel. (A), (b) is a figure which shows a mode that a black display image is observed in an example of the image display panel of this invention, respectively. (A), shows a black and white display state in an example of (b) is, respectively it images the display panel. (A), it shows a black and white display state in an example of (b) an image display panel according to the invention. (A) ~ (d) are views for describing the filling method of the image display medium in an example of the manufacturing method of their respective images display panel. (A)-(d) is a figure for demonstrating the filling method of an image display medium in an example of the manufacturing method of the image display panel of this invention, respectively.

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 5 and 6 Electrode 11 Recess 21 Holder 22 Blade

Claims (4)

A plurality of cells partitioned by a partition are formed between two opposing substrates at least one of which is transparent, and at least two types of image display media having different optical reflectance and charging characteristics are enclosed in the cells. An image display panel that displays an image by moving the image display medium by applying an electric field to the image display medium, and includes a partition wall provided to define the cell enclosing the image display medium. Comb line electrodes provided on both of the two substrates are provided in a line shape between the electrodes, and the barrier ribs and the comb line electrodes provided on both of the two substrates are orthogonal to each other. And formed so as to face each other, at least one partition provided on both of the two substrates has a recess that is lower than the height of the other part of the partition in the part to be joined to each other, The distance between the substrates is determined by the sum of the partition wall heights of the partition wall portions that are bonded to each other, and the total height of the partition wall portions of the partition wall portions that are bonded to each other is image display panel, wherein Rukoto exceed the height.   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 claim 1 or 2, wherein a partition wall is provided in a line shape between electrodes of comb-shaped line electrodes provided on both of the two substrates. Then, at least one of the two substrates is filled with an image display medium in one of the substrates having a partition wall having a recess lower than the height of the other part of the partition wall at a portion where the two substrates are bonded to each other. The provided line-shaped partition walls and the comb-shaped line-shaped electrodes are overlapped so as to be orthogonal to each other, thereby determining the distance between the substrates based on the total partition wall height of the partition wall portions joined to each other, and , total bulkhead height of the partition portion joining the mutually image producing method of a display panel, characterized in that the so that exceed the height of both the partition walls provided on both substrates.   As a method of filling an image display medium on at least one substrate side between partition walls provided in a line shape between electrodes of comb-shaped line electrodes provided on both of the two substrates, 4. The method for manufacturing an image display panel according to claim 3, wherein the image display medium is pushed by using a blade along the partition line direction.

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