JP2003307755A - Image display unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display unit which can reduce density unevenness and maintain display picture quality as an image display unit which is a dry type, has fast response performance and a simple structure, and is inexpensive and superior in stability. <P>SOLUTION: The image display unit is provided with an image display sheet which seals at least two types of particles different in color and electrification characteristics into between two substrates, at least one of which being transparent, and gives electric field to the particles from an electrode pair consisting of electrodes provided on one or both of the substrates to send the particles flying and display an image. In a first embodiment, the process of forming an image to be displayed comprises the step of applying to between electrodes an electric field pattern in a direction of a particle A flying to a displaying-side substrate to form an image, and the step of applying a pattern reverse (negative) to the above pattern in an electric field direction of a particle B, different in color and electrification characteristics from the particle A, flying to a display-side substrate to form an image, whereby an image deleting step prior to the step of forming an image to be displayed can be omitted. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device having an image display plate capable of repeatedly displaying and erasing an image as particles fly and move by utilizing Coulomb force.

[0002]

2. Description of the Related Art Conventionally, as an image display device replacing a liquid crystal (LCD), an image display device using a technique such as an electrophoretic system, an electrochromic system, a thermal system, and a two-color particle rotation system has been proposed.

[0003] These conventional techniques are advantageous in that they can obtain a wider viewing angle similar to ordinary printed matter, consume less power, and have a memory function as compared with LCDs. It is considered as a technology that can be used in devices, and is expected to be applied to image display for mobile terminals, electronic paper, and the like. In particular, recently, an electrophoretic method in which a dispersion liquid composed of dispersed particles and a coloring solution is formed into microcapsules and the microcapsules are arranged between opposed substrates has been proposed and expected. (See, for example, Non-Patent Document 1).

However, the electrophoretic 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. Further, 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 in that the image repeating stability is insufficient. Even in the case of microencapsulation, the cell size is set to the microcapsule level, and apparently the above-mentioned drawbacks are hard to appear, and no essential problem is solved.

On the other hand, a method in which conductive particles and a charge transport layer are incorporated in a part of a substrate without using a solution has begun to be proposed, as opposed to an electrophoretic method which utilizes behavior in a solution. However, since the structure is complicated because the charge transport layer and further the charge generation layer are arranged, it is difficult to inject the charge into the conductive particles constantly, and there is a problem that the stability is lacking.

[0006]

[Non-Patent Document 1] Zhao, 3 foreigners, "New Toner Display Device (I)", July 21, 1999,
Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcop
y'99 ”, p.249-252

[0007]

As a method for solving the above-mentioned various problems, at least one of two transparent substrates has two or more kinds of particles having different colors and different charging characteristics enclosed between them. 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 formed of electrodes provided on one or both of the substrates and causing the particles to fly and move by Coulomb force is known. There is.

This image display device has a display memory property (holds the display state even when the power is turned off).
In the case of an image display device with a display memory like this,
Both the electric field direction Ea in which the particle A flies to the display substrate side (polarity) and the electric field direction Eb in which the particle B different in color and charging characteristics from the particle A flies to the display substrate side are sequentially switched to obtain one image. Need to be formed. because,
When the image 1 made of particles A and B is rewritten to the image 2 made of particles A and B in the same manner, when an image is formed by Ea, only the part newly added to the image 2 by the particles A changes, This is because the portion of the particle B that must be added does not change.

Therefore, as shown in FIG. 6, after the image erasing process (the screen formed by only the particles A or B) is executed before the image formation, the electric field direction used for the image erasing is different. A method of forming an image in the direction of the electric field can be considered. 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 portion (line) where the image is formed in the first half of the frame time and the portion where the image is formed in the latter half of the frame time. In (line), since the time from the image formation until the image is erased at the beginning of the next frame is different, density unevenness occurs, and there is a problem that display image quality is significantly impaired.

An object of the present invention is to provide a dry type and quick response performance,
It is an object of the present invention to provide an image display device that has a simple structure, is inexpensive, and is excellent in stability, and that can reduce density unevenness and maintain display image quality.

[0011]

The image display device of the present invention has two or more kinds of particles having different colors and different charging characteristics enclosed between at least one transparent substrate, and one or both of the substrates. An electric field is applied to the particles from an electrode pair made up of electrodes provided in the image forming apparatus, and an image to be displayed is formed in an image display device including an image display plate that causes the particles to fly and move by Coulomb force to display an image. In the process, an electric field pattern in the direction in which the particles A fly to the display-side substrate is applied between the electrodes to form an image, and the particles B having different color and charging characteristics from the particles A fly to the display-side substrate. A step of forming an image by applying a reverse (negative) pattern of the above pattern in the direction of the electric field to be displayed, and omitting the step of erasing the image prior to the problem of forming the image to be displayed. It is an.

In the image display device of the present invention having the above-described structure, a novel image display is provided by arranging image display elements capable of directly moving an electrostatic field to particles to fly and move the particles by Coulomb force. By configuring the device, it is possible to provide an image display device having a high response speed, a simple structure, a low cost, and excellent stability. Also,
By omitting the image erasing process prior to the process of forming the image to be displayed, it is possible to reduce the density unevenness and maintain the display image quality.

In the image display device of the present invention, in the matrix display, the direction of the electric field is successively switched during the image forming process of the portion (usually every row) in which the display can be rewritten simultaneously, and the matrix is formed. In the display, it is preferable to form a plurality of portions (usually for each row) in which the display can be rewritten at the same time in the same electric field direction, and then to change the electric field direction to form the same portion in the image.

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 5 μC / m ² or more and 150 μC / m ² or less in absolute value. Further, when the particles were charged with a voltage of 8 KV to generate corona discharge to a corona discharger arranged at a distance of 1 mm from the surface to charge the surface, the surface potential of 0.3 seconds later was measured. It is preferable that the particles have a maximum value of more than 300V. Furthermore, it is preferable that the colors of the particles are white and black.

As the image display plate in the image display device of the present invention, it is preferable that the image display plate has one or more image display elements in which the electrode pairs of the matrix electrodes are separated from each other by the partition walls.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As will be described later in detail, the image display device to which the present invention is applied has two or more kinds of particles having different colors and different charging characteristics between at least two transparent substrates. An electric field is applied to the particles from an electrode pair made up of electrodes that are encapsulated and provided on one or both of the substrates to cause the particles to fly and move by Coulomb force to display an image. In the image display device having this configuration, the process of forming an image to be displayed is
The process of applying an electric field pattern in the direction in which the particles A fly to the display-side substrate to form an image, and the electric field direction in which the particles B having different color and charging characteristics from the particles A fly to the display-side substrate. And forming an image by applying a reverse (negative) pattern of the above pattern. In the present invention, as a concrete writing method, for example, E
After writing the binary pattern P with a, and writing the reverse (not (P)) (negative) of the pattern P with Eb, a desired image pattern can be formed, and image erasing (same color writing) By eliminating the process, it is possible to reduce the density unevenness and maintain the display image quality.

A description will be given below of a writing means which omits image erasing, which is a feature of the image display device of the present invention, with reference to the drawings. FIG. 1 and FIG. 2 are views for explaining an example of a writing means in the image display device of the present invention, in which the image erasing process is omitted. In each of the examples shown in FIGS. 1 and 2, in the matrix display of 7 rows × 5 columns, the number 1 is rewritten to the number 2.

In the example shown in FIG. 1, in the matrix display of 7 rows × 5 columns, the direction of the electric field is sequentially switched during the image forming process of the portion (usually every row) in which the display can be simultaneously rewritten to form an image. ing. In particular,
When the pattern of the number 2 1 ... N rows of the image to be written next is P1 ... Pn, when the direction of the electric field is sequentially switched for each row, the pattern P1 is set to Ea in the first row.
Then, the pattern Not (P1) is written with Eb, the pattern P2 is written with Ea in the second row, the pattern Not (P2) is written with Eb in the second row, and this is repeated until the pattern is finally written in the nth row. By writing Pn and then writing the pattern Not (Pn), the number 1 can be rewritten to the number 2.

In this example, in the case of matrix display, writing is performed by sequentially switching the electric field directions Ea and Eb row by row, so that moving image display without afterimage can be performed as compared with the case of FIG. 2 described later. it can.

In the example shown in FIG. 2, in the matrix display of 7 rows × 5 columns, the number 2 which is a writing pattern of 7 × 5 is written by Ea in the same electric field direction, and then 7 rows × 5.
It is possible to rewrite the numeral 1 into the numeral 2 by switching the electric field and writing by Eb in the inversion pattern formed by inverting the numeral 2 which is the writing pattern of the column.

In this example, in the case of matrix display, Ea
After the number 2 which is the writing pattern is image-formed for one screen, the negative of the number 2 which is the writing pattern is formed for one screen by switching to Eb. In this case, Ea
Even after the image is formed with, since the part of the particle A on the front screen that should originally be replaced by the particle B remains,
It is recognized as an afterimage on the moving image display. But,
The electric field switching frequency between Ea and Eb may be remarkably lower than that of the embodiment shown in FIG. 1, so that electromagnetic wave noise accompanying driving of the display element is small, and the frame due to the capacitance between the display element electrodes is small. The operating speed limit can also be increased.

FIG. 3 is a diagram showing an example of the image display element of the image display plate which constitutes the image display device of the present invention and the display driving principle thereof. 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, and 7 is a partition wall.

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). When a voltage is applied to this state such that the display electrode 3 side has a low potential and the counter electrode 4 side has a high potential, as shown in FIG. 3B, the Coulomb force causes the positively charged particles 6 to move to the display electrode 3 side. The negatively-charged particles 5 fly 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 has a high potential and the counter electrode 4 side has a low potential, FIG.
As shown in (c), the Coulomb force causes the negatively charged particles 5 to fly to the display electrode 3 side, and the positively charged particles 6 to 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.

Between FIG. 3 (b) and FIG. 3 (c), the display can be repeated by simply reversing the polarity of the power supply, and the color can be reversibly changed by reversing the polarity of the power supply. be able to. The color of the particles can be chosen 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 a reversible display between white and black. In this method, since each particle is once attached to the electrode by the image force, the display image is retained for a long time even after the voltage is cut off, and the memory retention property is good.

In the present invention, since each charged particle flies in gas, the response speed of image display is high, and the response speed is 1 ms.
It can be ec or less. Further, unlike a liquid crystal display element, an alignment film, a polarizing plate, etc. are not required, and the structure is simple, low cost and large area are possible. It is stable against temperature changes and can be used at low to high temperatures. Furthermore, there is no viewing angle, high reflectance, reflective type, easy to see even in bright places,
Low power consumption. It also has a memory function and does not consume power when holding an image.

The image display device of the present invention comprises an image display plate in which the above 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 each electrode to be n, an arbitrary n × n matrix can be constructed.

In the example shown in FIGS. 4A and 4B, the display electrodes 3-1 to 3-3 arranged substantially parallel to each other and the counter electrodes 4-1 to 4-3 arranged substantially parallel to each other are as follows. They are provided on the transparent substrate 1 and the counter substrate 2 in a state of being substantially orthogonal to each other. The display electrodes 3-1 to 3-3 are provided with two SW3-1-1 and SW3-1-sequentially, respectively.
2; SW3-2-1 and SW3-2-2; SW3-3-1
And SW3-3-2; are separately connected. Similarly,
The counter electrodes 4-1 to 4-3 are provided with two SW4-1-1 and SW4-1-2; SW4-2 provided in succession.
-1, SW4-2-2; SW4-3-1 and SW4-3-
2; are separately connected.

SW3-n-1 (n = 1 to 3) and SW4-
The n-1 (n = 1 to 3) serves to switch between connection to the ground and connection to the SW in the next stage. SW3-
n-2 (n = 1 to 3) and SW4-n-2 (n = 1 to 3)
And plays a role of switching between connection to the high voltage generation circuit 8 and connection to the low voltage generation circuit 9. The entire SW constitutes the matrix drive circuit 10. Further, in this example, the partition walls 7 are isolated from each other to form 3 × 3 image display elements, but the partition walls 7 are not essential and can be omitted.

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 is performed by opening and closing each SW under the control of a sequencer (not shown) according to an image to be displayed. Is controlled to sequentially display 3 × 3 image display elements. This operation is the same as that conventionally known.

In the case of display electrodes provided on a transparent substrate, each of the electrodes forming the matrix electrode is formed of a transparent and patternable conductive material. As such a conductive material, a metal such as aluminum, silver, nickel, copper, gold or a transparent conductive metal oxide such as ITO, conductive tin oxide, conductive zinc oxide or the like is formed by a sputtering method, a vacuum deposition method, a CVD method, 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 is used.

Examples of the conductive agent include cationic polymer electrolytes such as benzyltrimethylammonium chloride and tetrabutylammonium perchlorate, anionic polymer electrolytes such as polystyrene sulfonate and polyacrylate, and conductive zinc oxide and tin oxide. Indium oxide fine powder or the like is used. The electrode thickness may be any thickness as long as the conductivity can be secured and the light transmittance is not hindered, but 3 to 1000 nm, preferably 5 to 400 nm is suitable. On the counter substrate, a transparent electrode material may be used similarly to the display electrode, but aluminum,
Non-transparent electrode materials such as silver, nickel, copper and gold can also be used.

It is preferable to form an insulative coat layer on each electrode so that the charges of the charged particles do not escape.
The coat layer is a resin that is positively charged for negatively charged particles,
It is particularly preferable to use a negatively chargeable resin for the positively charged particles because the charge of the particles is difficult to escape.

The substrate used in the image display device of the present invention will be described below. 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 device, and a material having a high visible light transmittance and good heat resistance is suitable. Whether or not it is flexible is appropriately selected depending on the application. For example, it is flexible for electronic paper and other applications, and flexible for applications such as mobile phones, PDAs, and display devices of portable devices such as notebook computers. Materials without are preferred.

Examples of the material for the substrate include polymer sheets such as polyethylene terephthalate, polyether sulfone, polyethylene, polycarbonate, polyimide and acrylic, and inorganic sheets such as glass and quartz. The opposite substrate may be transparent or opaque. The thickness of the substrate is preferably 2 to 5000 μm, particularly 5 to 100 μm.
0 μm is preferred. If the thickness is too thin, it becomes difficult to maintain the strength and the uniformity of the spacing between the substrates, and if the thickness is too thick, the sharpness as a display function and the decrease in contrast occur,
In particular, it lacks flexibility in electronic paper applications.

Further, as shown in FIG. 3, it is preferable to provide the partition walls 7 on the four circumferences of each display element. The partition walls can be provided in two directions parallel to each other. As a result, it is possible to prevent excessive movement of particles in the direction parallel to the substrate, assist durability repeatability and memory retention, and evenly and reinforce the distance between the substrates to increase the strength of the image display plate. The method for forming the partition wall is not particularly limited, for example, a screen printing method in which paste is applied in a predetermined position using a screen plate, or a partition material having a desired thickness is solidly coated on a substrate to form a partition wall. After coating the resist pattern only on the part to be left on the partition material, sandblasting method of cutting and removing the partition material other than the partition part by injecting a blast material, or forming a resist pattern on the substrate using a photosensitive resin, A lift-off method (additive method) in which the resist is removed after the paste is embedded in the resist recesses, or a photosensitive paste method in which a photosensitive resin composition containing a partition material is applied on a substrate and a desired pattern is obtained by exposure and development. Or a mold forming method in which a barrier rib material-containing paste is applied on a substrate, and then a mold having irregularities is pressure-bonded and pressure-molded to form barrier ribs. How it is adopted. Furthermore, a relief embossing method is also applied in which a relief molding method is applied to use a relief pattern provided by a photosensitive resin composition as a template.

The particles used in the image display device of the present invention will be described below. In the present invention, the particles for display may be negative or positively charged colored particles and may be any particles as long as they fly and move by Coulomb's force, but spherical particles having a small specific gravity are particularly preferable. The average particle size of the particles is 0.1
50 μm is preferable, and 1 to 30 μm is particularly preferable. If the particle size is smaller than this range, the charge density of the particles is too large, the image force on the electrode or substrate is too strong, and the memory property is good, but
The trackability when the electric field is reversed becomes poor. On the contrary, if the particle size is larger than this range, the followability is good, but the memory property is poor.

The method of negatively or positively charging the particles is not particularly limited, but 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 carrier of particles is preferably in the range of 5 μC / m ² or more and 150 μC / m ² or less in absolute value. If the surface charge density is lower than this range, the response speed to changes in the electric field becomes slow and the memory property also becomes low.
When the surface charge density is higher than this range, the image force on the electrode or the substrate is too strong and the memory property is good, but the followability when the electric field is reversed becomes poor.

The measurement of the amount of charge and the measurement of the particle specific gravity, which are used in the present invention and are necessary for determining the surface charge density, were carried out 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 having meshes at both ends, high-pressure gas is blown from one end to separate the powder and carrier, and only powder is separated from the mesh openings. Blow off. At this time, a charge amount that is the same as the charge amount of the powder carried out of the container but is opposite to the charge amount remains on the carrier. Then, all the electric flux due to this electric charge is collected in the Faraday cage, and the capacitor is charged by this amount. Therefore, by measuring the potential across the capacitor, the charge Q of the powder can be obtained as Q = CV (C: capacitor capacity, V: voltage across the capacitor). As the blow-off powder charge amount measuring device, TB-200 manufactured by Toshiba Chemical Co. was used. In the present invention, two types of carriers, positively chargeable and negatively chargeable, are used, and the charge density per unit area (unit:
μC / m ² ) was measured. In other words, as a positively chargeable carrier (a carrier that makes the other party positively charged and is likely to become negative) F963-2535 made by Powdertech Co., Ltd., and a negatively charged carrier (the other party is negatively charged and itself becomes positively charged). As the easy carrier, F921-2535 manufactured by Powder Tech Co. was used. <Particle Specific Gravity Measuring Method> The particle specific gravity was measured with a specific gravity meter and multi-volume densitometer H1305 manufactured by Shimadzu Corporation.

Insulating particles having a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more are preferable because the particles are required to retain the charged electric charge, and particularly, the volume resistivity is 1 × 10 ¹² Ω · cm.
Insulating particles of cm or more are preferred. Further, particles having a low charge decay property evaluated by the method described below are more preferable.

That is, the particles are separately pressed, melted by heating,
A film having a thickness of 5 to 100 μm is formed by casting or the like. Then, a voltage of 8 KV is applied to a corona discharger arranged at a distance of 1 mm from the film surface to generate corona discharge to charge the surface, and the change in the surface potential is measured and judged. In this case, the particle constituent material is selected so that the maximum value of the surface potential after 0.3 seconds is larger than 300 V, preferably larger than 400 V,
It is essential to create.

The measurement of the surface potential is carried out by, for example, FIG.
It can be performed by the apparatus shown in (CRT2000 manufactured by QEA). In the case of this apparatus, the chuck 21 is provided on both ends of the shaft of the roll having the above-mentioned film arranged on the surface.
, The small scorotron discharger 22 and the surface electrometer 23 are separated from each other by a predetermined distance, and a measuring unit is placed opposite to the surface of the film with a space of 1 mm, and the film is kept stationary. A method of moving the measuring unit from one end of the film to the other end at a constant speed to measure the surface potential while applying the surface charge is suitably adopted. The measurement environment is temperature 25 ± 3
℃ and humidity 55 ± 5RH%.

The particles may be made of any material as long as the 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 or the like.

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. Resins, styrene acrylic resins, polyolefin resins, butyral resins, vinylidene chloride resins, melamine resins, phenol resins, fluororesins, polycarbonate resins, polysulfone resins, polyether resins, polyamide resins and the like, and two or more types may be mixed. it can.
In particular, acrylic urethane resin, acrylic silicone resin, acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are preferable from the viewpoint of controlling the adhesive force to the substrate.

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

Examples of the colorant include the following.
Various organic or inorganic pigments and dyes of various colors can be used.

Examples of black pigments include carbon black, copper oxide, manganese dioxide, aniline black and activated carbon. Examples of 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,
There are benzidine yellow G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake and the like. Orange pigments include red yellow lead, molybdenum orange, permanent orange GT
R, pyrazolone orange, vulcan orange, induslen brilliant orange RK, benzidine orange G, induslen brilliant orange GK and the like.
Red pigments include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R,
Examples include resole red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, and brilliant carmine 3B.

Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake.
Examples of blue pigments include navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated compound, fast sky blue, and indanthrene blue BC. Examples of green pigments include chrome green, chromium oxide, pigment green B, malachite green lake, and final yellow green G. Examples of white pigments 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. Also, basic, acidic, dispersion,
Examples of various dyes such as direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue. These colorants can be used alone or in combination. Particularly, carbon black is preferable as the black colorant, and titanium oxide is preferable as the white colorant.

The method for producing the particles is not particularly limited, but, for example, a pulverization method and a polymerization method according to the case of producing an electrophotographic toner can be used. Further, a method of coating the surface of the powder of the inorganic or organic pigment with a resin, a charge control agent or the like is also used.

The distance between the transparent substrate and the counter substrate should be such that particles can fly and move and the contrast can be maintained.
It is adjusted to 0 to 5000 μm, preferably 30 to 500 μm. The particle filling amount is 1 with respect to the space volume between the substrates.
It is good to fill so as to have a volume of 0 to 90%, preferably 30 to 80%.

In the display plate used in the image display device of the present invention, a plurality of the above-mentioned display elements are used and arranged in a matrix for display. In the case of black and white, one display element becomes one pixel. When displaying an arbitrary color other than black and white, the particle colors may be appropriately combined. In the case of full color, three types of display elements, that is, display elements each having particles of R (red), G (green) and B (blue) and having black particles respectively are set as a set and It is preferable to arrange a plurality of sets to form a display plate.

The image display device of the present invention is an image display unit of a mobile device such as a notebook computer, a PDA and a mobile phone.
It is used for electronic paper such as electronic books and electronic newspapers, signboards, posters, bulletin boards such as blackboards, calculators, home electric appliances, image display parts for automobile supplies and the like.

In the above-mentioned embodiments, the electrodes are provided on the substrate. However, in order to achieve the present invention, the electrodes may be formed on the substrate as long as there is an electrode for generating an electric field. The electrodes do not necessarily need to be present above, and the electrodes can be provided separately from the substrate.

[0054]

As is clear from the above description, according to the image display device of the present invention, the image display elements capable of directly applying an electrostatic field to the particles to cause the particles to fly and move are arranged in a matrix. As a result, a new image display device is configured, so the response speed is fast, the structure is simple, and the cost is low.
An image display device having excellent stability can be provided.
Further, since the image erasing process prior to the process of forming the image to be displayed can be omitted, it is possible to reduce the density unevenness and maintain the display image quality.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an example of a writing unit in which an image erasing process is omitted in the image display device of the present invention.

FIG. 2 is a diagram for explaining another example of a writing unit in the image display device of the present invention, in which an image erasing process is omitted.

3A to 3C are diagrams showing an example of a display element of an image display plate used in the image display device of the present invention and a display driving principle thereof.

4A and 4B are diagrams showing an example of an image display device of the present invention in which display elements are arranged in a matrix.

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 device.

FIG. 7 is a diagram for explaining a problem in the conventional example shown in 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 partition 8 High voltage generation circuit 9 Low voltage generation circuit 10 Matrix drive circuit 21 chuck 22 Scorotron discharger 23 Surface electrometer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yakushiji Manabu             3-2-6 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Kazuya Murata             3-5-5 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Koji Takagi             3-21-33-, Miyauchi, Nakahara-ku, Kawasaki-shi, Kanagawa             304 (72) Inventor Yoshitomo Masuda             3-5-28 Shinmeidai, Hamura-shi, Tokyo (72) Inventor Takahiro Kawagoe             1302-57 Aobadai, Tokorozawa, Saitama Prefecture (72) Inventor Reiji Hattori             200-1, Meinohamacho, Nishi-ku, Fukuoka City, Fukuoka Prefecture F-term (reference) 5C080 AA16 BB05 CC01 CC03 DD05                       DD08 EE24 EE26 FF07 FF12                       JJ01 JJ06 KK07 KK08 KK34                       KK43 KK47

Claims (8)

[Claims] 1. Two or more types of particles having different colors and different charging characteristics are enclosed between at least one transparent substrate, and an electrode pair consisting of electrodes provided on one or both of the substrates is formed into the particles. In an image display device provided with an image display plate that displays an image by applying an electric field to cause the particles to fly and move, the process of forming the image to be displayed is based on the direction in which the particles A fly to the substrate on the display side. A process of forming an image by applying an electric field pattern between the electrodes and an inversion (negative) pattern of the above pattern in the direction of the electric field in which the particle B having a color and a charging characteristic different from those of the particle A fly to the display side substrate. An image display device characterized in that the image erasing step prior to the step of forming an image to be displayed is omitted, including the step of forming an image. 2. The image display device according to claim 1, wherein in the matrix display, an image is formed by sequentially switching the direction of the electric field during an image forming process of a portion (usually row by row) where the display can be rewritten simultaneously. 3. The matrix display according to claim 1, wherein after a plurality of portions (usually row by row) in which the display can be rewritten at the same time are imaged in the same electric field direction, the electric field directions are switched to form the same portion. Image display device. 4. The image display device according to claim 1, wherein the average particle size of the particles is 0.1 to 50 μm. 5. The image display device according to claim 1, wherein a surface charge density measured by a blow-off method using a carrier of particles is 5 μC / m ² or more and 150 μC / m ² or less in absolute value. 6. When the particles have a corona discharger disposed at a distance of 1 mm from the surface of the particles, a voltage of 8 KV is applied to generate corona discharge to charge the surface.
The image display device according to any one of claims 1 to 5, which is a particle having a maximum surface potential of more than 300 V after 3 seconds. 7. The color of particles is white and black.
7. The image display device according to any one of to 6. 8. The image display device according to claim 1, wherein the image display plate has at least one image display element in which each electrode pair of the matrix electrode is separated from each other by a partition wall.