JP4436600B2 - Image display device - Google Patents

Description

【００５０】
表１の結果から、求めた評価結果と、Ｗ／Ｒ、Ｈ／Ｒ、Ｉ／Ｒとの関係を検討したところ、Ｗ／Ｒは２を超えることが、Ｈ／Ｒは２を超えることが、Ｉ／Ｒは５０未満であることが、本発明において好ましいことがわかった。
【００５１】
なお、上述した実施例では、電極を基板上に設けた例を示しているが、本発明を達成するためには、電界を発生するための電極が存在しさえすれば電極は基板上に必ずしも存在する必要はなく、電極を基板とは離して設けることもできる。
【００５２】
【発明の効果】
以上の説明から明らかなように、本発明によれば、電極表面に設けた微小凹部および／または微小凸部によって部分的に微小不均一電界を導入でき、この微小凹部および・または微小凸部によって発生する微小な不均一電界は横方向、すなわち基板面と平行な方向への電界成分を有するため、横方向に移動しようとする粒子に対し積極的に吸引もしくは排斥することで粒子を固定し、凝集による偏在を抑制できる。その結果、耐久使用時の画質劣化を改良することができる。
【図面の簡単な説明】
【図１】 （ａ）〜（ｃ）はそれぞれ本発明の画像表示装置に用いる画像表示板の表示素子の一例とその表示駆動原理を示す図である。
【図２】 （ａ）〜（ｈ）はそれぞれ電極表面に複数個形成した微小凹部および／または微小凸部の一例を説明するための図である。
【図３】 セグメント表示装置に本発明を適用した一例を示す図である。
【図４】 セグメント表示装置における対向基板の一例を示す図である。
【図５】 セグメント表示装置における透明電極の一例を示す図である。
【図６】 セグメント表示装置におけるスクリーンパターン（レジストパターン）の一例を例を示す図である。
【図７】 粒子の表面電位の測定要領を示す図である。
【符号の説明】
１、２２ 透明基板
２、２４ 対向基板
３ 表示電極
４ 対向電極
５ 負帯電粒子
６ 正帯電粒子
１１、２５ 微小切り欠き
１２ 電極
２１ セグメント表示装置
２３ スペーサ
２６ セグメント電極
２７ 開口
３１ チャック
３２ スコロトロン放電器
３３ 表面電位計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display device including an image display plate capable of repeatedly displaying and erasing an image with the flying movement of particles using Coulomb force, and more particularly to an image display device having improved image quality deterioration during durable use.
[0002]
[Prior art]
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 replace liquid crystal (LCD).
[0003]
These conventional technologies can be used for next-generation and inexpensive image display devices because they have advantages such as a wide viewing angle that is close to that of ordinary printed materials, low power consumption, and memory functions compared to LCDs. It is considered as a technology that can be developed, 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 expected. (For example, refer nonpatent literature 1).
[0004]
However, the electrophoresis method has a problem that the response speed is slow due to the viscous resistance of the liquid because the particles migrate in the liquid. Furthermore, since particles having a high specific gravity such as titanium oxide are dispersed in a solution having a low specific gravity, they are liable to settle, it is difficult to maintain the stability of the dispersed state, and there is a problem that the stability of image repetition is lacking. Even with microencapsulation, the cell size is set to the microcapsule level, and the above-described drawbacks are made difficult to appear, and the essential problems are not solved.
[0005]
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 has been proposed in contrast to an electrophoresis method using behavior in a solution. However, since the charge transport layer and further the charge generation layer are arranged, the structure becomes complicated, and it is difficult to inject the charges into the conductive particles uniformly, and there is a problem that the stability is lacking.
[0006]
[Non-Patent Document 1]
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”, p.249-252
[0007]
[Problems to be solved by the invention]
As one method for solving the above-mentioned various problems, two or more kinds of particles having different colors and charging characteristics are sealed between two substrates, at least one of which is transparent, and an electrode comprising an electrode provided on the substrate There is known an image display apparatus including an image display plate that displays an image by applying an electric field to particles from a pair and causing the particles to fly and move by Coulomb force.
[0008]
When this image display device repeatedly displays and erases an image, the particles move in a direction parallel to the substrate due to the cohesive force and gravity of the particles themselves, resulting in coarse and dense portions of the particles, resulting in image display defects or contrast. Cause a drop. For this reason, an idea has been proposed in which the space between both substrates is finely divided by partition walls to form a cell structure to suppress the lateral movement of particles. However, this method using the barrier ribs reduces the effective display area to deteriorate the contrast, makes it difficult to fill the cells with particles when manufacturing the image display device, and manufactures the image display device to form the barrier ribs. There was a problem of increasing costs.
[0009]
An object of the present invention is to improve the durability characteristics by suppressing image quality deterioration due to particle aggregation during repeated image display in an image display device that is dry, has quick response performance, has a simple structure, is inexpensive, and has excellent stability. It is an object of the present invention to provide an image display device that can be used.
[0010]
[Means for Solving the Problems]
The image display device of the present invention encloses two or more kinds of particles having different colors and charging characteristics between two substrates, at least one of which is transparent, and applies an electric field to the particles from an electrode pair comprising electrodes provided on the substrate. Te, projected shape of the image display apparatus comprising an image display panel for displaying an image by ejecting move particles, (1) Rutotomoni provided a small recess in the entire plane of the surface of the electrode, the electrode surface of the micro recesses When the average diagonal length is the average width, the average of the absolute values of the depth from the electrode surface of the minute recesses is the average depth, and the largest average particle size of two or more types of particles is the maximum average particle size (1) The micro-recesses were formed so that the average width / maximum average particle diameter> 2 and the average depth / maximum average particle diameter> 2, and (2) the micro-protrusions were provided on the entire surface of the electrode. , Average the absolute value of the height from the electrode surface of the minute projection Assuming that the largest average particle diameter of two or more types of particles is the maximum average particle diameter, the average width / maximum average particle diameter> 2 and the average height / maximum average particle diameter> 2. (3) Provided with micro concave portions and micro convex portions on the entire surface of the electrode, the average diagonal length of the projected shape on the electrode surface of the micro concave portion as the average width, and the electrode of the micro concave portion When the average of the absolute values of the depths from the surface is defined as the average depth, and the largest average particle size of two or more types of particles is defined as the maximum average particle size, the average width / maximum average particle size> 2 and the average depth The maximum average particle diameter of the two or more kinds of particles is formed by forming the minute recesses so that the thickness / maximum average particle diameter> 2, and taking the average of the absolute values of the heights from the electrode surface of the minute protrusions as the average height. When the diameter is the maximum average particle diameter, the average width / maximum average particle diameter 2, and the average height / maximum average particle size of> 2, and so as to have configured the minute projections is characterized in.
[0011]
In contrast, the electric field for particle flight given by the electrode pair provided on each of two substrates arranged in parallel is a uniform electric field, whereas in the image display device of the present invention configured as described above, A minute non-uniform electric field can be partially introduced by the provided minute recesses and / or minute protrusions. The minute non-uniform electric field generated by the minute recesses and / or the minute protrusions has an electric field component in the horizontal direction, that is, in a direction parallel to the substrate surface, and therefore is actively attracted to particles moving in the horizontal direction. Alternatively, the particles can be fixed by being rejected and uneven distribution due to aggregation can be suppressed.
[0012]
In the image display device of the present invention, since the degree of the influence of the non-uniform electric field obtained by the minute recesses and / or the minute protrusions on the particles is determined by the relationship with the average particle diameter of the particles, the average particle diameter and the minute recesses and From the standpoint of obtaining a non-uniform electric field of a predetermined value or more by defining the relationship with the dimensions of the micro-convex portions, the average diagonal length of the projection shape on the electrode surface of the micro-concave portions and / or the micro-projections portions Is the average width, and the average of the absolute values of the depth and / or height of the minute recesses and / or minute protrusions from the electrode surface is the average height (depth), and the largest average of the two or more types of particles When the particle diameter is defined as the maximum average particle diameter, the minute recesses and / or the minute protrusions may be configured such that average width / maximum average particle diameter> 2 and average height / maximum average particle diameter> 2. preferable. If the above relationship cannot be achieved, a non-uniform electric field of a predetermined value or more cannot be obtained, so that the image quality deterioration due to particle aggregation at the time of repeated image display of the present invention is suppressed, and the durability characteristics are sufficiently improved. I can't.
[0013]
In the image display device according to the present invention, when a minute concave portion and / or a minute convex portion are provided on the display electrode side requiring light transmittance, the thickness of an ITO transparent electrode or the like usually used as a thin film of about several tens of nm is increased. However, since it is difficult in terms of optical characteristics in terms of manufacturing method, it is preferable to obtain the same effect by providing a transparent insulating layer on the electrode and providing a minute concave portion and / or a minute convex portion on the transparent insulating layer. Further, the insulating resin can be printed in a dot shape by a screen printing method or the like and used as a minute convex portion. In this case, if the dot occupation area ratio is sufficiently small, the resin may not be transparent.
[0014]
In the image display device of the present invention, it is preferable to arrange a plurality of minute recesses and / or minute protrusions at intervals because a minute non-uniform electric field can be applied to a large electrode surface, that is, a large pixel. Alternatively, it is preferable that the average interval between the minute protrusions is set so that the average interval / maximum average particle size <50. In this case, the effect of generating a non-uniform electric field due to the minute recesses and / or the minute protrusions can be continuously obtained over a wide range.
[0015]
Further, under certain conditions, a slight decrease in contrast may be observed in the minute concave portion and / or the minute convex portion. In order to ensure the contrast of the entire display portion, the minute concave portion and / or the minute convex portion may be observed. The total area of the projected shape on the electrode surface is preferably 50% or less with respect to the electrode area. Furthermore, in order to sufficiently obtain the effects of the minute recesses and / or the minute protrusions, the total area of the minute recesses and / or the minute protrusions is preferably 0.1% or more with respect to the electrode area.
[0016]
The particles in the image display device of the present invention preferably have an average particle diameter of 0.1 to 50 μm. Further, it is preferable that the surface charge density measured by a blow-off method using a carrier of particles is 150μC / m ² or less 5 [mu] C / m ² or more in absolute value. Furthermore, when the surface is charged by generating a corona discharge by applying a voltage of 8 KV to a corona discharger in which the particles are arranged at a distance of 1 mm from the surface, the surface potential after 0.3 seconds It is preferred that the maximum value be particles larger than 300V. Furthermore, the color of the particles is preferably white and black.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an example of an image display element of an image display board constituting the image display apparatus of the present invention and its display driving principle. In the example shown in FIGS. 1A to 1C, 1 is a transparent substrate, 2 is a counter substrate, 3 is a display electrode (transparent electrode), 4 is a counter electrode, 5 is negatively charged particles, and 6 is positively charged particles. is there.
[0018]
FIG. 1A shows a state in which negatively charged particles 5 and positively charged particles 6 are arranged between opposing substrates (transparent substrate 1 and opposing substrate 2). In this state, when a voltage is applied so that the display electrode 3 side is at a low potential and the counter electrode 4 side is at a high potential, the positively charged particles 6 are caused to move to the display electrode 3 by Coulomb force as shown in FIG. The negatively charged particles 5 fly and move to the opposite electrode 4 side. In this case, the display surface viewed from the transparent substrate 1 side looks like the color of the positively charged particles 6. Next, when the polarity is switched and a voltage is applied so that the display electrode 3 side is at a high potential and the counter electrode 4 side is at a low potential, the negatively charged particles 5 are displayed by the Coulomb force as shown in FIG. The positively charged particles 6 fly and move to the electrode 3 side, and fly to the counter electrode 4 side. In this case, the display surface viewed from the transparent substrate 1 side looks like the color of the negatively charged particles 6.
[0019]
Between FIG. 1 (b) and FIG. 1 (c), it is possible to repeatedly display only by reversing the polarity of the power source. In this way, the color can be reversibly changed by reversing the polarity of the power source. . The color of the particles can be selected at will. For example, when the negatively charged particles 5 are white and the positively charged particles 6 are black, or the negatively charged particles 5 are black and the positively charged particles 6 are white, the display is reversible between white and black. In this method, since each particle is once attached to the electrode by mirror image force, the display image is retained for a long time even after the voltage is turned off, and the memory retainability is good.
[0020]
In the present invention, since each charged particle flies in the gas, the response speed of image display is high, and the response speed can be 1 msec or less. Further, unlike the liquid crystal display element, an alignment film, a polarizing plate, and the like are unnecessary, the structure is simple, and the cost and the large area are possible. It is stable against temperature changes and can be used from low to high temperatures. Furthermore, there is no viewing angle, high reflectivity, reflection type, easy to see even in bright places, and low power consumption. It also has memory characteristics and does not consume power when holding images.
[0021]
In the image display device described with reference to FIGS. 1A to 1C, in the present invention, a minute recess, a minute protrusion, or a minute recess is formed on a part or the entire surface of an electrode (here, the display electrode 3 and the counter electrode 4). And a minute convex part (described later) are provided. At that time, the shape of the minute recesses and / or the minute protrusions is important. The average diagonal length of the projected shape of the minute recesses and / or the minute protrusions on the electrode surface is the average width, and the minute recesses and / or the minute protrusions are used. When the average of the absolute value of the depth and / or height from the electrode surface of the portion is the average height (depth), and the largest average particle size of two or more types of particles is the maximum average particle size, the average It is preferable to configure the minute recesses and / or the minute protrusions so that the width / maximum average particle diameter> 2 and the average height / maximum average particle diameter> 2.
[0022]
In the image display device of the present invention, the minute concave portion and / or the minute convex portion on the electrode surface may be a circle, an ellipse, a square, a rectangle, a polygon, a line, a curve, an indefinite shape, or a combination thereof. . In particular, in the segment display in which the area of one pixel is increased, the same effect can be obtained on a large screen by repeatedly arranging the minute concave portions and / or the minute convex portions. In this case, as a method of repeated placement, lattice placement, staggered lattice placement, pitch variation placement, random placement, and the like are conceivable.
[0023]
2A to 2H are diagrams for explaining an example of a plurality of minute recesses or minute protrusions formed on the electrode surface. FIG. 2A shows an example in which circular minute recesses 11 are arranged in a grid on the surface of the electrode 12, and FIG. 2B shows an example in which racetrack-shaped minute recesses 11 are arranged in a lattice on the surface of the electrode 12. FIG. 2C shows an example in which the circular minute recesses 11 are arranged in a staggered manner on the surface of the electrode 12, and FIG. 2D shows an example in which the race track-shaped minute recesses 11 are arranged in a staggered manner on the surface of the electrode 12. Show. Further, FIG. 2 (e) shows an example in which circular minute convex portions 13 are arranged in a grid on the surface of the electrode 12, and FIG. 2 (f) shows an example in which minute concave portions 11 made of linear slits are arranged in parallel. Indicates. Further, FIG. 2G shows an example in which conical minute convex portions 13 are arranged in a staggered manner, and FIG. 2H shows a waffle type example in which square minute concave portions 11 are arranged on the electrode 12.
[0024]
FIG. 3 is a diagram showing an example in which the present invention is applied to a segment display device. In the example shown in FIG. 3, the segment display device 21 is configured by laminating a transparent substrate 22, a spacer 23, and a counter substrate 24. A transparent electrode (not shown) having a shape along each segment of the display pattern is provided on the surface of the transparent substrate 22 on the spacer 23 side. As the spacer 23, a black spacer having an opening 27 according to the shape of each segment of the display pattern is used. On the surface of the counter substrate 24 on the spacer 23 side, seven segment electrodes 26 provided with a plurality of circular minute recesses 25 are formed for each segment. The transparent electrode and the segment electrode 26 are provided with an electrode lead wire (not shown) and connected to a drive circuit (not shown). Each of the seven openings 27 of the spacer 23 is filled with two or more kinds of particles having different colors and charging characteristics, for example, positively charged particles and negatively charged particles as in the above-described example. The thickness of the spacer 23 is adjusted so that the distance between the electrodes becomes a predetermined distance. The operation of the segment display device 21 shown in FIG. 3 is the same as that of the image display device described above.
[0025]
In the segment display device 21 described above, the segment electrode 26 having the minute recesses 25 is formed by forming a plurality of minute recesses 25 by etching on the surface of one side of an aluminum plate having a square of 100 mm × 100 mm and a thickness of 1 mm, for example. It can be produced by cutting into a shape.
[0026]
As another example, the counter substrate 24 (FIG. 4) on which the segment electrode 26 having minute convex portions is formed can be manufactured as follows. That is, first, as shown in FIG. 5, the segment electrode 26 along the display pattern is formed on the glass substrate by the ITO transparent electrode. Next, as shown in FIG. 6, a screen having an opening at a position where a minute convex portion is to be formed is prepared, and this screen is superimposed on a glass substrate having a segment electrode 26 formed on the surface, and a PDP rib is formed from the opening. A predetermined counter substrate 24 can be manufactured by attaching the paste for use to the surface of the segment electrode 26. At that time, by adjusting the viscosity of the paste and the size of the opening, the height of the minute convex portion can be set to a predetermined value.
[0027]
As yet another example, the counter substrate 24 (FIG. 4) on which the segment electrodes 26 having minute recesses are formed can be manufactured as follows. That is, first, as shown in FIG. 5, the segment electrode 26 along the display pattern is formed on the glass substrate by the ITO transparent electrode. Next, a resist film is stuck on the entire surface of the glass substrate to a thickness of 50 microns, exposed to UV with a photomask (see FIG. 6) along the display pattern, and minute recesses are formed in the segment electrodes 26 by etching. Thus, a predetermined counter substrate 24 can be manufactured. At this time, the depth of the minute recesses can be set to a predetermined value by adjusting the etching time.
[0028]
Hereinafter, the substrate used in the image display device of the present invention will be described. At least one of the substrates is a transparent substrate in which the color of the particles can be confirmed from the outside of the apparatus, and a material having high visible light transmittance and good heat resistance is preferable. The presence or absence of flexibility is appropriately selected depending on the application. For example, flexible materials are used for applications such as electronic paper, and flexibility is used for applications such as display devices for portable devices such as mobile phones, PDAs and notebook computers. A material with no is preferred.
[0029]
Examples of the substrate material include polymer sheets such as polyethylene terephthalate, polyether sulfone, polyethylene, polycarbonate, polyimide, and acrylic, and inorganic sheets such as glass and quartz. The counter substrate may be transparent or opaque. The thickness of the substrate is preferably 2 to 5000 μm, particularly preferably 5 to 1000 μm. If the thickness is too thin, it will be difficult to maintain the strength and the uniformity of the distance between the substrates. If the thickness is too thick, the sharpness and contrast of the display function will be reduced, especially in the case of electronic paper applications. Lack of tea.
[0030]
Hereinafter, the particles used in the image display device of the present invention will be described. In the present invention, the display particles may be any negative or positively charged colored particles that can be moved by a Coulomb force. Particularly, spherical particles having a small specific gravity are preferable. The average particle diameter of the particles is preferably from 0.1 to 50 μm, particularly preferably from 1 to 30 μm. If the particle size is smaller than this range, the charge density of the particles is too large and the image force on the electrode or substrate is too strong, and the memory performance is good, but the followability when the electric field is reversed is poor. On the other hand, if the particle size is larger than this range, the followability is good, but the memory property is poor.
[0031]
A method of charging the particles negatively or positively is not particularly limited, and a method of charging the particles such as a corona discharge method, an electrode injection method, and a friction method is used. It is preferable that the surface charge density measured by a blow-off method using a carrier of particles is 5 [mu] C / m ² or more 150μC / m ² or less in absolute value. When the surface charge density is lower than this range, the response speed with respect to the change of the electric field is lowered and the memory property is also lowered. When the surface charge density is higher than this range, the mirror image force on the electrode and the substrate is too strong and the memory property is good, but the followability when the electric field is reversed is deteriorated.
[0032]
The measurement of the charge amount and the particle specific gravity necessary for determining the surface charge density used in the present invention were performed as follows.
<Blow-off measurement principle and method>
In the blow-off method, a mixture of powder and carrier is placed in a cylindrical container with nets at both ends, high pressure gas is blown from one end to separate the powder and carrier, and only the powder is removed from the mesh opening. Blow off. At this time, the charge amount equal to the charge amount taken away from the container by the powder remains on the carrier. All of the electric flux due to this charge is collected by the Faraday cage, and the capacitor is charged by this amount. Therefore, by measuring the potential across the capacitor, the charge quantity Q of the powder is
Q = CV (C: Capacitor capacity, V: Voltage across capacitor)
As required.
TB-200 manufactured by Toshiba Chemical Co. was used as a blow-off powder charge measuring device. In the present invention, two types of carriers of positive chargeability and negative chargeability were used as the carrier, and the charge density per unit area (unit: μC / m ² ) was measured in each case. In other words, F963-2535 manufactured by Powdertech Co., Ltd. is used as a positively chargeable carrier (a carrier that tends to be negatively charged when the other party is positively charged). As an easy carrier, F921-2535 made by Powdertech was used.
<Particle specific gravity measurement method>
The particle specific gravity was measured with a hydrometer and a multi-volume density meter H1305 manufactured by Shimadzu Corporation.
[0033]
Since the particles need to retain their charged charges, insulating particles having a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more are preferable, and insulating particles having a volume resistivity of 1 × 10 ¹² Ω · cm or more are particularly preferable. Further, particles having a low charge attenuating property evaluated by the method described below are more preferable.
[0034]
That is, the particles are separately formed into a film having a thickness of 5 to 100 μm by pressing, heat melting, casting, or the like. Then, a voltage of 8 KV is applied to a corona discharger disposed at a distance of 1 mm from the film surface to generate a corona discharge to charge the surface, and a change in the surface potential is measured and determined. In this case, it is important to select and prepare the particle constituent material so that the maximum value of the surface potential after 0.3 seconds is larger than 300V, preferably larger than 400V.
[0035]
The measurement of the surface potential can be performed, for example, with the apparatus shown in FIG. 7 (CRT2000 manufactured by QEA). In the case of this apparatus, the above-mentioned measuring unit is provided with both ends of the shaft of the roll having the above-described film disposed on the surface thereof by the chuck 31 and a small scorotron discharger 32 and a surface potential meter 33 separated from each other by a predetermined distance. The surface potential is applied while giving a surface charge by moving the measuring unit at a constant speed from one end to the other end of the film while the film is placed in a stationary state with a distance of 1 mm from the surface of the film. The method of measuring is preferably employed. The measurement environment is a temperature of 25 ± 3 ° C. and a humidity of 55 ± 5 RH%.
[0036]
The particles may be composed of any material as long as charging performance and the like are satisfied. For example, it can be formed from a resin, a charge control agent, a colorant, an inorganic additive, or the like, or a colorant alone.
[0037]
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.
[0038]
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.
[0039]
As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.
[0040]
Examples of black pigments include carbon black, copper oxide, manganese dioxide, aniline black, and activated carbon. Yellow pigments include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline There are yellow rake, permanent yellow NCG, tartrage rake and so on. Examples of the orange pigment include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK. Red pigments include Bengala, 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. Rake, Brilliant Carmine 3B, etc.
[0041]
Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake. Examples of blue pigments include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, fast sky blue, and induslen blue BC. Examples of the green pigment include chrome green, chromium oxide, pigment green B, malachite green lake, final yellow green G, and the like. Examples of white pigments include zinc white, titanium oxide, antimony white, and zinc sulfide.
[0042]
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. These colorants can be used alone or in combination. In particular, carbon black is preferable as the black colorant, and titanium oxide is preferable as the white colorant.
[0043]
The method for producing the particles is not particularly limited, and for example, a pulverization method and a polymerization method according to the case of producing an electrophotographic toner can be used. In addition, a method of coating a resin, a charge control agent, or the like on the surface of an inorganic or organic pigment powder is also used.
[0044]
The distance between the transparent substrate and the counter substrate is not limited as long as particles can fly and maintain the contrast, but is usually adjusted to 10 to 5000 μm, preferably 30 to 500 μm. The particle filling amount may be 10 to 90%, preferably 30 to 80% of the space volume between the substrates.
[0045]
In the display panel used in the image display device of the present invention, a plurality of the above display elements are used and arranged in a matrix to perform display. In the case of black and white, one display element becomes one pixel. When displaying an arbitrary color other than black and white, a combination of particle colors may be appropriately performed. In the case of full color, a set of three display elements, that is, display elements each having R (red), G (green) and B (blue) color particles and each having black particles, It is preferable to arrange a plurality of sets to form a display board.
[0046]
The image display device of the present invention includes an image display unit of a mobile device such as a notebook computer, a PDA, and a mobile phone, an electronic book such as an electronic book, an electronic newspaper, a bulletin board such as a signboard, a poster, and a blackboard, a calculator, a household appliance, and an automobile product. It is used for an image display unit.
[0047]
In the above-described embodiment, the example in which the partition wall is not used is described because of the structure of the image display device, but it may be used together with the cell structure using the partition wall. In this case, since the cell size can be increased and the ratio of the partition walls to the display area can be reduced, higher contrast can be obtained.
[0048]
Next, in the image display device of the present invention, in order to examine the relationship between the maximum average particle diameter R of the particles and the minute recesses and / or the minute protrusions, the minute recesses having the shapes and arrangement states shown in Table 1 below are used. One electrode is arranged with the average width W, average height (depth) H, and average interval I shown in Table 1 below, and the substrate interval D and the maximum average particle diameter R of the particles are shown in Table 1 below. The image display devices of Examples 1 to 6 adjusted as described above were prepared. For the prepared image display devices of Examples 1 to 6, evaluation was performed by applying a rectangular wave of 4 (kV / mm) at 1 (Hz) for 10 seconds, then applying at 10 (Hz) for 30 seconds, and then Evaluation was performed by visually judging the degree of image degradation due to particle aggregation while performing inversion at 1 (Hz). In Table 1, ◎ indicates that no image deterioration was observed, ○ indicates that there was almost no image deterioration, and Δ indicates that image deterioration was partially observed but there was no practical problem. Show. The results are shown in Table 1.
[0049]
[Table 1]

[0050]
From the results of Table 1, when the relationship between the obtained evaluation results and W / R, H / R, and I / R was examined, W / R may exceed 2 and H / R may exceed 2. It was found that I / R is less than 50 in the present invention.
[0051]
In the above-described embodiment, an example in which the electrode is provided on the substrate is shown. However, in order to achieve the present invention, the electrode is not necessarily provided on the substrate as long as an electrode for generating an electric field exists. It does not need to be present, and the electrode can be provided separately from the substrate.
[0052]
【The invention's effect】
As is apparent from the above description, according to the present invention, a minute non-uniform electric field can be partially introduced by the minute recesses and / or minute projections provided on the electrode surface. The generated non-uniform electric field has an electric field component in the horizontal direction, that is, in a direction parallel to the substrate surface, so that the particles are fixed by positively attracting or rejecting the particles moving in the horizontal direction, Uneven distribution due to aggregation can be suppressed. As a result, it is possible to improve image quality degradation during durable use.
[Brief description of the drawings]
FIGS. 1A to 1C are diagrams showing an example of a display element of an image display board used in the image display apparatus of the present invention and a display driving principle thereof, respectively.
FIGS. 2A to 2H are views for explaining an example of a plurality of minute recesses and / or minute protrusions formed on the electrode surface.
FIG. 3 is a diagram showing an example in which the present invention is applied to a segment display device.
FIG. 4 is a diagram illustrating an example of a counter substrate in a segment display device.
FIG. 5 is a diagram showing an example of a transparent electrode in a segment display device.
FIG. 6 is a diagram illustrating an example of a screen pattern (resist pattern) in a segment display device.
FIG. 7 is a diagram showing a procedure for measuring the surface potential of particles.
[Explanation of symbols]
1, 22 Transparent substrate 2, 24 Counter substrate 3 Display electrode 4 Counter electrode 5 Negatively charged particle 6 Positively charged particle 11, 25 Minute notch 12 Electrode 21 Segment display device 23 Spacer 26 Segment electrode 27 Opening 31 Chuck 32 Scorotron discharger 33 Surface electrometer

Claims (9)

Two or more kinds of particles having different colors and charging characteristics are encapsulated between two substrates at least one of which is transparent, and an electric field is applied to the particles from an electrode pair consisting of electrodes provided on the substrate to cause the particles to fly and move. an image display apparatus comprising an image display panel for displaying an image, Rutotomoni fine concave portion provided on the entire surface of the surface of the electrode, the average diagonal length of the projected shape of the electrode surface of the minute recesses and average width, When the average of the absolute values of the depths from the electrode surface of the minute recesses is the average depth, and the largest average particle size among the two or more types of particles is the maximum average particle size, the average width / maximum average particle size> 2, In addition, the image display device is characterized in that the minute recesses are configured so that the average depth / the maximum average particle diameter> 2 . The image display apparatus according to claim 1, wherein a plurality of minute recesses are arranged on the same electrode, and an average interval between them is set to be an average interval / maximum average particle diameter <50. The image display device according to claim 1, wherein an insulating layer is provided on the surface of the electrode, and a minute recess is provided in the insulating layer. Two or more kinds of particles having different colors and charging characteristics are encapsulated between two substrates at least one of which is transparent, and an electric field is applied to the particles from an electrode pair consisting of electrodes provided on the substrate to cause the particles to fly and move. an image display apparatus comprising an image display panel for displaying an image, a fine small protrusions provided on the entire surface of the surface of the electrode Rutotomoni average average high Satoshi the absolute value of the height from the electrode surface of the minute projections Slightly convex so that average width / maximum average particle diameter> 2 and average height / maximum average particle diameter> 2 when the largest average particle diameter of two or more kinds of particles is defined as the maximum average particle diameter part image display apparatus characterized by being configured to. 5. The image display device according to claim 4, wherein a plurality of minute convex portions are arranged with respect to the same electrode, and an average interval between them is an average interval / maximum average particle diameter <50. 6. The image display device according to claim 4, wherein an insulating layer is provided on the surface of the electrode, and a minute convex portion is provided on the insulating layer. Two or more kinds of particles having different colors and charging characteristics are encapsulated between two substrates at least one of which is transparent, and an electric field is applied to the particles from an electrode pair consisting of electrodes provided on the substrate to cause the particles to fly and move. an image display apparatus comprising an image display panel for displaying an image, a beauty fine small protrusions Oyo minute recesses on the entire surface of the surface of the electrode is provided, the average diagonal length of the projected shape of the electrode surface of the micro recesses When the average width is defined as the average depth, the average of the absolute values of the depths from the electrode surface of the minute recesses is defined as the average depth, and the largest average particle size among the two or more types of particles is defined as the maximum average particle size. Constructing the minute recesses so that the diameter> 2 and the average depth / maximum average particle diameter> 2, and the average of the absolute values of the heights of the minute protrusions from the electrode surface is the average height, and two or more types The largest average particle size among the particles of When in an average width / maximum average particle size of> 2 and an average height / maximum average particle size of> 2, and so as the image display apparatus being characterized in that it constitutes the minute projections. The image display device according to claim 7, wherein a plurality of minute recesses and a plurality of minute protrusions are arranged with respect to the same electrode, and an average interval between them is an average interval / maximum average particle diameter <50. 9. The image display device according to claim 7, wherein an insulating layer is provided on the surface of the electrode, and a minute concave portion and a minute convex portion are provided on the insulating layer .

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