JP4397157B2 - Image display device - Google Patents

Description

[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 as a particle moves using Coulomb force.
[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 various problems described above, 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 provided on one or both of the substrates. There is known an image display device including an image display plate that displays an image by applying an electric field to the particles from an electrode pair including electrodes and causing the particles to fly and move by Coulomb force.
[0008]
This image display device has a display memory property (a display state is maintained even when the power is turned off). Thus, in the case of an image display device having a display memory property, Ea which is the electric field direction (polarity) in which the particles A fly to the display substrate side, and particles B having a color and charging characteristics different from those of the particle A are on the display substrate side. It is necessary to form one image by sequentially switching both of the flying electric field directions Eb. This is because, when the image 1 made of the particles A and B is rewritten to the image 2 made of the particles A and B in the same manner, when the image is formed with Ea, only the part newly added to the image 2 with the particles A is obtained. This is because the portion that has changed and has to be written with the particle B does not change.
[0009]
Therefore, as shown in FIG. 6, after an image erasing process (a screen formed of only particles A or B) is performed prior to image formation, the electric field direction is different from the electric field direction used for image erasing. A method of forming an image is conceivable. However, for example, in the matrix display, as shown in FIG. 7, when the image is erased at the beginning of the frame time, the part (line) where the image is formed at the first half of the frame time and the part where the image is formed at the second half of the frame time In (Line), there is a problem in that density unevenness occurs because the time from image formation to image erasing at the beginning of the next frame is different, and display quality is significantly impaired.
[0010]
An object of the present invention is to provide an image display device that can reduce density unevenness and maintain display image quality in an image display device that is dry, has quick response performance, has a simple structure, is inexpensive, and has excellent stability. Is.
[0011]
[Means for Solving the Problems]
The image display device of the present invention includes two or more kinds of particles having different colors and charging characteristics between two substrates, at least one of which is transparent, and an electrode pair comprising electrodes provided on one or both of the substrates. In the image display device including an image display plate that displays an image by applying an electric field to the particles and causing the particles to fly and move, a process of forming an image to be displayed includes: Next, the pattern of 1 to n rows of n rows × m columns of images to be written next is set to P1 to Pn, and the inverted (negative) patterns thereof are Not (P1) to Not (Pn). In this case, the pattern P1 is written in the first row with the electric field Ea in the direction in which the particles A fly to the substrate on the display side, and then the inverted pattern Not (P1) is displayed with the particles B having different colors and charging characteristics from the particles A. Write with the electric field Eb in the direction of flight to the substrate on the side, write the pattern P2 with the electric field Ea in the second row, write the pattern Not (P2) with the electric field Eb, repeat this up to n rows, and write next n rows Xm lines of images are displayed process Consist of The image erasing process prior to the process of forming the image to be displayed is omitted.
Also, the image display device of the present invention is an electrode comprising two or more kinds of particles having different colors and charging characteristics between two substrates, at least one of which is transparent, and an electrode formed on one or both of the substrates. In the image display device including an image display plate that displays an image by applying an electric field to the particles from a pair and causing the particles to fly and move, a process of forming an image to be displayed includes: Next, the pattern of 1 to n rows of n rows × m columns of images to be written next is set to P1 to Pn, and the inverted (negative) patterns thereof are Not (P1) to Not (Pn). Then, the pattern P1 is written in the first row with the electric field Ea in the direction in which the particles A fly to the substrate on the display side, then the pattern P2 is written in the second row with the electric field Ea, and this is repeated up to n rows. The pattern Not (P1) is written in the first row with the electric field Eb in the direction in which the particles B having different colors and charging characteristics from the particles A fly to the substrate on the display side, and then the pattern Not (P2) is written in the second row. Writing is performed with the electric field Eb, this is repeated up to n rows, and the next n rows × m rows of images are displayed. process Consist of The image erasing process prior to the process of forming the image to be displayed is omitted.
[0012]
In the image display device of the present invention configured as described above, a novel image display device is configured by arranging image display elements that can directly apply electrostatic fields to the particles and cause the particles to fly and move by Coulomb force. By doing so, it is possible to provide an image display device that has a high response speed, a simple structure, is inexpensive, and has excellent stability. Further, by omitting the image erasing process prior to the process of forming the image to be displayed, density unevenness can be reduced and display image quality can be maintained.
[0014]
The particles in the image display device of the present invention preferably have an average particle diameter of 0.1 to 50 μm. The surface charge density measured by the blow-off method using a particle carrier is 5 μC / m in absolute value. ² 150 μC / m ² The following is preferable. 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.
[0015]
The image display plate in the image display device of the present invention preferably has a configuration in which the image display plate includes one or more image display elements in which each electrode pair of matrix electrodes is separated from each other by a partition wall.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
As will be described in detail later, an image display device that is an object of the present invention encloses two or more types of particles having different colors and charging characteristics between two substrates, at least one of which is transparent, An image display plate is provided that displays an image by applying an electric field to the particles from an electrode pair including electrodes provided on both, and causing the particles to fly and move by Coulomb force. In the image display device having this configuration, the process of forming an image to be displayed includes the process of forming an image by applying an electric field pattern between the electrodes in the direction in which the particles A fly to the display-side substrate, Includes a process of forming an image by applying a reversal (negative) pattern of the pattern in the electric field direction in which the particles B having different colors and charging characteristics fly to the substrate on the display side. In the present invention, as a specific writing method, for example, a binary pattern P is written by Ea, and then a desired image pattern is formed by writing inversion (not (P)) (negative) of the pattern P by Eb. By eliminating the image erasing (same color writing) process, density unevenness can be reduced and display image quality can be maintained.
[0017]
Referring to the drawings, description will be given of writing means that omits image erasure, which is a feature of the image display device of the present invention. FIG. 1 and FIG. 2 are diagrams for explaining an example of writing means in which the image erasing process is omitted in the image display apparatus of the present invention. In the example shown in FIG. 1 and FIG. 2, an example is shown in which the number 1 is rewritten to the number 2 in a matrix display of 7 rows × 5 columns.
[0018]
In the example shown in FIG. 1, in the matrix display of 7 rows × 5 columns, the image is formed by sequentially switching the direction of the electric field during the image forming process of the portion where the display can be rewritten simultaneously (usually for each row). Specifically, when the pattern of the number 2 1... N rows, which is the next image to be written, is P1... Pn, the pattern P1 is changed to the first row when the direction of the electric field is sequentially switched for each row. Write with Ea, then write pattern Not (P1) with Eb, write pattern P2 with Ea on the second row, then write pattern Not (P2) with Eb, repeat this, and finally on the nth row The number 1 can be rewritten to the number 2 by writing the pattern Pn and then writing the pattern Not (Pn).
[0019]
In this example, in the case of matrix display, by sequentially switching Ea and Eb and the electric field direction for each row and writing, moving image display without afterimage can be performed as compared with the case of FIG.
[0020]
In the example shown in FIG. 2, in the matrix display of 7 rows × 5 columns, the number 2 which is a 7 × 5 writing pattern is written with Ea in the same electric field direction, and then the number is the writing pattern of 7 rows × 5 columns. The number 1 can be rewritten to the number 2 by writing an inversion pattern formed by reversing 2 in Eb while switching the electric field.
[0021]
In this example, in the case of matrix display, the number 2 as the writing pattern is formed for one screen by Ea, and then the negative of the number 2 as the writing pattern is formed by switching to Eb for one screen. In this case, even after the image is formed with Ea, the portion of the particle A on the previous screen that must be replaced with the particle B remains, and thus it is recognized as an afterimage on the moving image display. However, since the frequency of the electric field switching between Ea and Eb may be significantly lower than that in the embodiment shown in FIG. 1, the generation of electromagnetic noise due to the display element driving is small, and the capacitance between the display element electrodes is small. The limit of the frame operation speed can be increased.
[0022]
FIG. 3 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. 3A to 3C, 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, 6 is positively charged particles, 7 is a partition.
[0023]
FIG. 3A shows a state in which the negatively charged particles 5 and the positively charged particles 6 are arranged between the opposing substrates (the transparent substrate 1 and the 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.
[0024]
Between FIG. 3 (b) and FIG. 3 (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.
[0025]
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.
[0026]
The image display device of the present invention is composed of an image display plate in which the image display elements are arranged in a matrix. An example of the schematic diagram is shown in FIGS. In this example, a 3 × 3 matrix is shown for convenience of explanation. By setting the number of electrodes to n, an arbitrary n × n matrix can be configured.
[0027]
In the example shown in FIGS. 4A and 4B, the display electrodes 3-1 to 3-3 arranged almost in parallel to the counter electrodes 4-1 to 4-3 arranged almost in parallel are almost orthogonal to each other. In this state, it is provided on the transparent substrate 1 and the counter substrate 2. Two SW3-1-1 and SW3-1-2; SW3-2-1 and SW3-2-2; SW3-3-1 are provided on the display electrodes 3-1 to 3-3, respectively. And SW3-3-2; are connected to each other. Similarly, two counter electrodes 4-1 to 4-3 are provided in succession, SW4-1-1 and SW4-1-2; SW4-2-1 and SW4-2-2; SW4-. 3-1 and SW 4-3-2 are connected to each other.
[0028]
SW3-n-1 (n = 1 to 3) and SW4-n-1 (n = 1 to 3) play a role of switching between connection to the ground and connection to the next-stage SW. SW3-n-2 (n = 1 to 3) and SW4-n-2 (n = 1 to 3) serve to switch the connection to the high voltage generation circuit 8 and the connection to the low voltage generation circuit 9. Fulfill. The entire SW constitutes the matrix drive circuit 10. Further, in this example, 3 × 3 image display elements are configured by being separated from each other by the partition wall 7, but the partition wall 7 is not essential and can be omitted.
[0029]
The operation of the matrix electrode composed of the display electrodes 3-1 to 3-3 and the counter electrodes 4-1 to 4-3 described above controls the opening and closing of each SW by the control of a sequencer (not shown) according to the image to be displayed. Thus, 3 × 3 image display elements are sequentially displayed. This operation is the same as that conventionally known.
[0030]
In the case of a display electrode provided on a transparent substrate, each electrode constituting the matrix electrode is formed of a conductive material that is transparent and can be patterned. Examples of such conductive materials include metals such as aluminum, silver, nickel, copper, and gold, and transparent conductive metal oxides such as ITO, conductive tin oxide, and conductive zinc oxide by sputtering, vacuum deposition, CVD, A thin film formed by a coating method or the like, or a conductive agent mixed with a solvent or a synthetic resin binder and applied.
[0031]
Conductive agents include cationic polymer electrolytes such as benzyltrimethylammonium chloride and tetrabutylammonium perchlorate, anionic polymer electrolytes such as polystyrene sulfonate and polyacrylate, and conductive zinc oxide, tin oxide, and indium oxide. Fine powder or the like is used. The electrode thickness may be any thickness as long as conductivity can be ensured and there is no problem with light transmittance, but it is preferably 3 to 1000 nm, preferably 5 to 400 nm. A transparent electrode material can be used on the counter substrate in the same manner as the display electrode, but non-transparent electrode materials such as aluminum, silver, nickel, copper, and gold can also be used.
[0032]
It is preferable to form an insulating coating layer on each electrode so that the charge of charged particles does not escape. For the coating layer, it is particularly preferable to use a positively chargeable resin for the negatively charged particles and a negatively chargeable resin for the positively charged particles because the charge of the particles is difficult to escape.
[0033]
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.
[0034]
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.
[0035]
Moreover, as shown in FIG. 3, it is preferable to provide the partition 7 in the four periphery of each display element. The partition walls can be provided in two parallel directions. Thereby, excessive particle movement in the substrate parallel direction can be prevented, durability repeatability and memory retention can be assisted, and the space between the substrates can be uniformly and reinforced to increase the strength of the image display plate. The method for forming the partition is not particularly limited. For example, a screen printing method in which a paste is repeatedly applied at a predetermined position using a screen plate, or a partition material having a desired thickness is solidly coated on the substrate to form a partition. After coating the resist pattern only on the partition material on the part to be left, the blast material is sprayed to remove the partition material other than the partition part, and the resist pattern is formed using a photosensitive resin on the substrate. A lift-off method (additive method) for removing the resist after embedding the paste in the resist recess, or a photosensitive paste method for applying a photosensitive resin composition containing a partition material on the substrate to obtain a desired pattern by exposure and development Also, after applying a paste containing partition wall material on the substrate, mold molding method etc. to form partition walls by pressing and pressure forming a mold with irregularities etc. How it is adopted. Furthermore, a relief molding method using a mold patterning method and using a relief pattern provided with a photosensitive resin composition as a mold is also employed.
[0036]
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.
[0037]
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. The surface charge density measured by the blow-off method using a particle carrier is 5 μC / m in absolute value. ² 150 μC / m ² The following ranges are preferred. When the surface charge density is lower than this range, the response speed with respect to the change of the electric field becomes slow, and the memory property becomes low. 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.
[0038]
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 are used as carriers, and charge density per unit area in each case (unit: μC / m) ² ) Was measured. 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.
[0039]
Since the particles need to retain their charged charge, the volume resistivity is 1 × 10 ¹⁰ Insulating particles of Ω · cm or more are preferable, and the volume resistivity is 1 × 10. ¹² Insulating particles of Ω · cm or more are preferable. Further, particles having a low charge attenuating property evaluated by the method described below are more preferable.
[0040]
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.
[0041]
In addition, the measurement of the said surface potential can be performed, for example with the apparatus (CRT2000 by QEA) shown in FIG. In the case of this apparatus, the above-mentioned measuring unit is provided with both ends of the shaft of the roll on which the above-mentioned film is arranged held by the chuck 21 and the small scorotron discharger 22 and the surface potential meter 23 are 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%.
[0042]
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.
[0043]
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.
[0044]
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.
[0045]
As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.
[0046]
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.
[0047]
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.
[0048]
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.
[0049]
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.
[0050]
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.
[0051]
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.
[0052]
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.
[0053]
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.
[0054]
【The invention's effect】
As is apparent from the above description, according to the image display device of the present invention, a novel image is obtained by arranging image display elements capable of flying and moving particles by directly applying an electrostatic field to the particles. Since the display device is configured, it is possible to provide an image display device having a high response speed, a simple structure, low cost, and excellent stability. Further, since the image erasing process prior to the process of forming the image to be displayed can be omitted, density unevenness can be reduced and the display image quality can be maintained.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an example of writing means in which an image erasing process is omitted in an image display device of the present invention.
FIG. 2 is a diagram for explaining another example of writing means in which an image erasing process is omitted in the image display apparatus of the present invention.
FIGS. 3A to 3C 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. 4A and 4B are diagrams showing an example of an image display device according to the present invention in which display elements are arranged in a matrix. FIG.
FIG. 5 is a diagram showing a procedure for measuring the surface potential of particles.
FIG. 6 is a diagram for explaining image rewriting means in a conventional image display apparatus.
7 is a diagram for explaining problems in the conventional example shown in FIG. 6; FIG.
[Explanation of symbols]
1 Transparent substrate
2 Counter substrate
3 Display electrodes
4 Counter electrode
5 Negatively charged particles
6 Positively charged particles
7 Bulkhead
8 High voltage generator
9 Low voltage generator
10 Matrix drive circuit
21 Chuck
22 Scorotron discharger
23 Surface potential meter

Claims (7)

Encapsulating two or more kinds of particles having different colors and charging characteristics between two substrates at least one of which is transparent, and applying an electric field to the particles from an electrode pair comprising electrodes provided on one or both of the substrates, In an image display device comprising an image display plate that displays the image by flying and moving the particles,
In the process of forming an image to be displayed, an image of n rows × m columns to be written next is a pattern of 1 to n rows each consisting of m pixels, P1 to Pn, and their inverted (negative) pattern Is set to Not (P1) to Not (Pn), the pattern P1 is written in the first row by the electric field Ea in the direction in which the particles A fly to the substrate on the display side, and then the inverted pattern Not (P1) is written to the particles A. Is written with the electric field Eb in the direction in which the particles B having different colors and charging characteristics fly to the substrate on the display side, the pattern P2 is written with the electric field Ea in the second row, and then the pattern Not (P2) is written with the electric field Eb. An image display apparatus comprising: a step of repeating the process up to n lines and displaying an image of n lines × m lines to be written next, and omitting an image erasing process prior to a process of forming an image to be displayed. Encapsulating two or more kinds of particles having different colors and charging characteristics between two substrates at least one of which is transparent, and applying an electric field to the particles from an electrode pair comprising electrodes provided on one or both of the substrates, In an image display device comprising an image display plate that displays the image by flying and moving the particles,
In the process of forming an image to be displayed, an image of n rows × m columns to be written next is a pattern of 1 to n rows each consisting of m pixels, P1 to Pn, and their inverted (negative) pattern Is set to Not (P1) to Not (Pn), the pattern P1 is written in the first row with the electric field Ea in the direction in which the particles A fly to the substrate on the display side, and then the pattern P2 is written in the second row with the electric field Ea. Writing is repeated up to n rows, and then pattern Not (P1) is written in the first row with an electric field Eb in a direction in which particles B having different colors and charging characteristics from the particles A fly to the substrate on the display side. the writing electric field Eb pattern Not (P2) in the second row, which repeated until n rows, then writes consist process for displaying an image of n rows × m lines, the process of forming an image to be displayed Prior to image deletion An image display device characterized in that the process is omitted. The image display apparatus according to claim 1 or 2 average particle diameter of the particles is 0.1 to 50 [mu] m. The image display apparatus according to any one of claims 1 to 3 surface charge density measured by a blow-off method is 150μC / m ² or less 5 [mu] C / m ² or more in absolute value with the carrier particles. When the surface is charged by applying a voltage of 8 KV to a corona discharger in which particles are arranged at a distance of 1 mm from the surface to charge the surface, the maximum value of the surface potential after 0.3 seconds The image display device according to any one of claims 1 to 4 , wherein the particle size is larger than 300V. The image display apparatus according to any one of claims 1 to 5 the color of the particles are white and black. Image display plate, the image display apparatus according to any one of claims 1 to 6 having one or more image display elements isolated from each other by respective electrode pairs partition wall matrix electrodes.

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