JP2003222912A - Device and method for displaying image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for displaying an image, which is of a dry type, has high response speed, has a simple structure and further is excellent in stability and sharpness and a method therefor. <P>SOLUTION: Particles having mutually different charging characteristics are sealed in a space between two transparent substrates equipped with a backlight, a color filter and two pairs of electrodes. An electric field is produced between the substrates to fly and move the particles and thereby display the image. <P>COPYRIGHT: (C)2003,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 and an image display method capable of repeatedly displaying and erasing an image as particles fly and move by utilizing Coulomb force or the like.

[0002]

2. Description of the Related Art As an image display device replacing liquid crystal (LCD), an image display device (display) using a technique such as an electrophoretic system, an electrochromic system, a thermal system, and a two-color particle rotation system has been proposed. These image display devices are considered as next-generation inexpensive display devices because they have a wider viewing angle than ordinary printed matter, lower power consumption, and a memory function than LCDs. Therefore, it is expected to be applied to displays for mobile terminals and electronic papers.

Recently, an electrophoretic method has been proposed 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. 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, there is a problem in that they easily settle, it is difficult to maintain the stability of the dispersed state, and the stability of image repetition is lacking. Even in the case of microencapsulation, the cell size is set to the microcapsule level, and such defects are apparently difficult to appear, and no essential problem is solved.

In contrast to the electrophoretic method utilizing the behavior in the solution as described above, recently, a method in which conductive particles and a charge transport layer are incorporated in a part of the substrate has been proposed without using the solution. However, this method has a problem in that the structure is complicated because the charge transport layer and the charge generation layer are arranged, and it is difficult to uniformly dissipate the charges from the conductive particles, resulting in lack of stability. Further, the method of displaying using particles as described above has a drawback that it is difficult to display a clear image due to insufficient brightness. (For example, Non-Patent Document 1
reference)

[0005]

[Non-Patent Document 1] Japan Imaging Society "Japan Hardcopy '99"
Proceedings July 21, 1999, p. 249-252

[0006]

SUMMARY OF THE INVENTION The present invention relates to a new type of image display device that has been earnestly studied in view of the above-mentioned circumstances, and has a dry structure, a fast response speed, a simple structure, stability, and vividness. An object of the present invention is to provide an image display device and an image display method which are excellent in properties.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that between two transparent substrates provided with a backlight, a color filter and two pairs of electrodes. By encapsulating particles with different charging characteristics and applying an electric field between the substrates to fly and move the particles to display an image, the response speed is fast, the structure is simple, and the image is excellent in stability and sharpness. The inventors have found that a display device can be obtained, and completed the present invention.

That is, the present invention provides the following image display device and image display method. 1. Encapsulating particles having different charging characteristics between two transparent substrates provided with a backlight, a color filter and two pairs of electrodes, and applying an electric field between the substrates to fly and move the particles to display an image. An image display device characterized by. 2. The image display device according to the above 1, wherein the average particle diameter d _{0.5 of the} particles is 0.1 to 50 μm. 3. The surface charge density of particles measured and calculated by the blow-off method using a carrier is 5 to 150 μC / m in absolute value.
^2. The image display device according to 1 or 2 above. 4. The image display device according to any one of 1 to 3 above, wherein the particles are insulating particles having a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more. 5. The maximum value of the surface potential after 0.3 seconds when the particles are charged with a corona discharge by applying a voltage of 8 kV to the corona discharger arranged at a distance of 1 mm from the surface to generate corona discharge. The image display device according to any one of 1 to 4 above, wherein the particles are larger than 300V. 6. The image display device according to any one of 1 to 5 above, wherein the color of the particles is black. 7. 7. The image display device according to any one of 1 to 6 above, which has one or more image display elements separated from each other by a partition wall. Of the 8.2 pairs of electrodes, one pair is an electrode pair provided in a central portion of the substrate, and the other pair is an electrode pair provided in a peripheral portion of the substrate and / or a partition wall. Image display device. 9. An image display method by the image display device according to any one of 1 to 8 above.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the image display device of the present invention, particles having different charging characteristics are enclosed between two transparent substrates provided with a backlight, a color filter and two pairs of electrodes, and the two substrates are charged between the substrates. An electric field is applied to cause particles to fly and move to display an image. Here, the force applied to the particles may be a force that attracts each other due to the Coulomb force between the particles, an electric image force with the electrode plate, an intermolecular force, a liquid bridge force, and gravity.

Hereinafter, an example of the display element of the image display device of the present invention and its display operation principle will be described with reference to the drawings. FIG. 1 shows a color filter 9, a transparent electrode (A electrode) 3 and an insulator 1 inside a transparent display substrate 1 (a side facing a counter substrate).
The C electrode 5 isolated by 2 is provided, and the transparent electrode (B electrode) 4 and the electrode (D electrode) 6 isolated by the insulator 12 inside the transparent counter substrate 2 (the side facing the display substrate). Is installed, and the backlight 10 is illuminated from the outside of the transparent counter substrate 2. FIG. 1A shows a state in which negatively chargeable particles 7 and positively chargeable particles 8 are arranged between two transparent substrates facing each other. In this state, with the power supply, the A electrode 3 side is the negative electrode,
When a voltage is applied so that the B electrode 4 side becomes a positive electrode, FIG.
As shown in (b), due to Coulomb force and the like, the positively charged particles 8 fly and move to the A electrode 3 side, and the negatively charged particles 7 move to B side.
It flies to the electrode 4 side. In this case, the display surface viewed from the display substrate 1 side is in a non-display state (usually black) because the light from the backlight 10 is blocked. Next, by switching the polarity of the power source, dropping the A electrode 3 and the B electrode 4 to the ground, and applying a voltage so that the C electrode 5 becomes the negative electrode and the D electrode 6 becomes the positive electrode, as shown in FIG. 1 (c). The negatively chargeable particles 7 fly to the D electrode 6 and the positively chargeable particles 8 fly to the C electrode 5 due to Coulomb force. In this case, the display surface viewed from the display substrate 1 side is in a display state and looks like the color of the color filter 9. Since a backlight is used and the space is gas, bright and clear color display is provided. Between FIG. 1 (b) and FIG. 1 (c), display can be repeated by simply switching the polarity of the power source, and the display can be reversibly changed. For example, if the negatively chargeable particles 5 and the positively chargeable particles 8 are black and the color filter 7 is R (red), G (green) or B (blue), each color can be displayed. In the method of the present invention, since each particle is attached to the electrode by the image force, the displayed image is retained for a long time even after the power is turned off, and the memory retention property is good. Further, since the charged particles fly and move in the gas by Coulomb force or the like, the display speed is very fast and can be 10 msec or less.

In FIG. 2, the C electrode 5 and the D electrode 6 are separated by a partition wall 11.
2A shows a state in which the negatively chargeable particles 7 and the positively chargeable particles 8 are arranged between two transparent substrates facing each other. In this state, power supply A
When voltage is applied so that the electrode 3 side becomes the negative electrode and the B electrode 4 side becomes the positive electrode, the positively chargeable particles 8 fly and move to the A electrode 3 side due to the Coulomb force as shown in FIG. Particles 7 fly to the B electrode 4 side. in this case,
The display surface viewed from the display substrate 1 side is in a non-display state (usually black) because light from the backlight 10 is blocked. Next, by switching the polarity of the power source, dropping the A electrode 3 and the B electrode 4 to the ground, and applying a voltage so that the C electrode 5 becomes the positive electrode and the D electrode 6 becomes the negative electrode, as shown in FIG. 2 (c). The negatively chargeable particles 7 fly to the C electrode 5 and the positively chargeable particles 8 fly to the D electrode 6 due to Coulomb force. In this case, the display surface viewed from the display substrate 1 side is in a display state and looks like the color of the color filter 9. Figure 2
Between (b) and FIG. 2 (c), display can be repeated by simply switching the polarity of the power source, and the color can be reversibly changed.

Regarding the substrate, both the display substrate 1 and the counter substrate 2 are transparent substrates in which the display color can be confirmed from the outside of the display plate, and a material having high visible light transmittance and good heat resistance is preferable. Is. 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 thickness of the substrate is preferably from 2 to 5000 μm, and particularly preferably from 5 to 1000 μm. When the thickness is too thin, it becomes difficult to maintain strength and the uniformity of the distance between the substrates. A drop occurs.

The A and B electrodes are made of a transparent and patternable conductive material, such as aluminum,
A thin film made of a metal such as silver, nickel, copper or gold or a transparent conductive metal oxide such as ITO, conductive tin oxide or conductive zinc oxide by a sputtering method, a vacuum deposition method, a CVD method, a coating method or the like. Alternatively, 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, tin oxide and indium oxide. Fine powder or the like is used. In addition, the electrode thickness may be 3 to 1000 nm, preferably 5 to 400 nm, as long as the conductivity can be secured and the light transmittance is not hindered. As the C electrode and the D electrode, the above-mentioned transparent electrode materials can be used, but non-transparent electrode materials such as aluminum, silver, nickel, copper and gold can also be used. In this case, the external voltage may be applied by superimposing DC or AC on it. It is preferable to form an insulating coat layer on each electrode so that the charges of the charged particles do not escape. This coat layer is particularly preferable when a positively chargeable resin is used for the negatively chargeable particles and a negatively chargeable resin is used for the positively chargeable particles because the charge of the particles is difficult to escape.

In the image display device of the present invention, it is preferable to provide partition walls 11 as shown in each drawing on the four circumferences of each display element. The partition walls can be provided in two directions parallel to each other. As a result, excessive movement of particles in the direction parallel to the substrate can be prevented, durability repeatability and memory retention can be assisted, and the distance between the substrates can be made uniform and reinforced 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 wall material, a blasting material is sprayed to remove the partition wall material other than the partition wall by sandblasting, or a resist pattern is formed on the substrate using a photosensitive resin. , Lift-off method (additive method) that removes resist after embedding paste in resist recess
Or a photosensitive paste method in which a partition wall material-containing photosensitive resin composition is applied onto the substrate and a desired pattern is obtained by exposure and development, or after a partition wall material-containing paste is applied onto the substrate Various methods such as a mold forming method in which a mold having irregularities is pressure-bonded and pressure-molded to form partition walls are used. Further, a relief embossing method is also applied in which a relief molding method is applied, in which a relief pattern provided by a photosensitive resin composition is used as a template.

The particles for display in the image display device of the present invention may be any negatively or positively charged colored particles that can fly and move by Coulomb force or the like, but in particular,
Spherical particles with a low specific gravity are preferred. The average particle diameter d _0.5 of the particles is preferably 0.1 to 50 μm, and particularly 1 to 30
μm is preferred. If the average particle size d _0.5 is less 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 property is good, but the followability when the electric field is reversed becomes poor. On the other hand, if it exceeds this range, the followability is good, but the memory property is poor. In addition, in the present invention, the average particle diameter d _0.5 (μm) is calculated by Mastersizer2000 (Malv
ern instruments Ltd.) Put each particle into the measuring machine and use the attached analysis software (software that calculates the particle size distribution and particle size based on the volume-based distribution) to find that 50% of the particles are larger than this. % Is a numerical value expressed in μm as a particle diameter that is smaller than this.

The charge amount of the particles naturally depends on the measurement conditions, but the charge amount of the particles in the image display device is almost dependent on the initial charge amount, the contact with the substrate, the contact with other particles, and the charge decay with the passage of time. It has been found that the saturation value of the charging behavior associated with the contact of charged particles is the controlling factor. However, this is difficult with simple measurements. As a result of intensive studies, the inventors of the present invention can predict the charge amount of particles suitable for an image display device by measuring the charge amount by a measurement method using a carrier in the blow-off method and defining the charge amount by the surface charge density. Found.
Although the measuring method will be described in detail later, the charge amount per unit weight of the particles can be measured by sufficiently contacting the particles with the carrier particles by the blow-off method and measuring the saturated charge amount. . Then, the surface charge density of the particles can be calculated by separately determining the particle diameter and the specific gravity of the particles.

In the image display device, the particle diameter of the particles used is small and the effect of gravity is so small that it can be ignored. Therefore, the specific gravity of the particles does not affect the movement of the particles. However, in terms of the charge amount of particles, even if the particles having the same particle diameter have the same average charge amount per unit weight, the charge amount held when the specific gravity of the particles is two times different will be two times different. Therefore, the charging characteristics of the particles used in the image display device have a surface charge density (unit: μC /
It has been found preferable to evaluate by m ² ). Here, the larger the surface charge density, the better. In an image display device, when the particle size of a particle is large, the electric image force tends to be a factor that mainly determines the flying electric field (voltage). Therefore, in order to move the particle at a low electric field (voltage), the charge amount is large. The lower the better. Also,
When the particle size is small, non-electrical forces such as intermolecular force and liquid bridging force are often determinants of the flight electric field (voltage). Therefore, in order to move this particle with a low electric field (voltage), The higher the charge amount, the better. In addition, since this largely depends on the surface property (material, shape) of the particle, it cannot be unconditionally specified by the particle size and the amount of charge, but when the surface charge density of the particle is appropriate, the particles have different characteristics. The function of moving in the direction of the electrode by the electric field will be fulfilled.

The present inventors have found that the average particle diameter d _0.5 is 0.1 to 0.1.
For particles of 50 μm, the surface charge density of the particles measured by the blow-off method using a carrier is 5 in absolute value.
found that that can be a particle that can be used as an image display apparatus in the case where [mu] C / m ² or more 150μC / m ² or less. If the surface charge density is less 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 exceeds 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 deteriorates. In this blow-off method, a mixture of particles and a carrier is placed in a cylindrical container having meshes on both ends,
High-pressure gas is blown from one end to separate the particles from the carrier, and only the particles are blown off (blown away) from the mesh openings. At this time, a charge amount opposite to the charge amount of the powder carried away from the container remains in the carrier. Then, all of 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 amount of the powder can be calculated as Q =
It is obtained as CV (C: capacitor capacity, V: voltage across capacitor). Then, the surface charge density is obtained from this charge amount, the average particle diameter d _0.5 and the specific gravity of the particles, which are separately measured.

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. Since the particles need to retain their charged electric charge, the volume resistivity is 1
× preferably ¹⁰ 10 Ω · cm or more insulating particles, especially 1 ×
Insulating particles of 10 ¹² Ω · cm or more are preferable.

Further, the particles in the image display device of the present invention are more preferably particles having a slow charge decay property evaluated by the method described below. That is, a voltage of 8 kV is applied to a corona discharger arranged at a distance of 1 mm from the surface of the particles to generate corona discharge to charge the surface, and the change in the surface potential is measured and judged. In this case, it is desirable 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. The surface potential is measured, for example, by the device shown in FIG. 3 (CRT20 manufactured by QEA).
00). With this device,
A chuck 21 holds both ends of the roll shaft having the above-mentioned particles arranged on the surface thereof, and a small scorotron discharger 2
2 and the surface electrometer 23 are separated from each other by a predetermined distance, and a measurement unit is placed opposite to the surface of the particles with a distance of 1 mm, and the measurement unit of the roll shaft is fixed while the roll shaft is stationary. A method of measuring the surface potential while applying a surface charge by moving it from one end to the other at a constant speed is suitably adopted. The measurement environment is 25 ± 3 ° C. and humidity is 55 ± 5 RH%.

The particles in the image display device of the present invention may be made of any material as long as characteristics such as charging performance 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. 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. , Especially from the viewpoint of controlling the adhesion with the substrate, acrylic urethane resin, acrylic silicone resin,
Acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are suitable. It is also possible to mix two or more kinds.

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 a nigrosine dye, a triphenylmethane compound, a quaternary ammonium salt compound, a polyamine resin, and an imidazole derivative. 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.

As the colorant, various organic or inorganic pigments and dyes of various colors can be used as shown below. 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, benzidine yellow G, benzidine yellow GR, quinoline. Yellow rake, permanent yellow NCG, tartrazine rake, etc. 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.

Examples of red pigments include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, resole red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine. Rake B, Alizarin Rake, Brilliant Carmine 3B, etc. Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake.
Examples of blue pigments include dark 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, chrome 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. Further, various dyes such as basic dyes, acid dyes, dispersion dyes and 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. An example of producing 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. 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 substrates in the image display device of the present invention should be such that particles can fly and move and the contrast can be maintained, but it is usually 10 to 5000 μm, preferably 1
It is adjusted to 0 to 500 μm. The volume occupancy of the particles in the space between the opposing substrates is preferably 10 to 80%, more preferably 10 to 60%. If it exceeds 80%, the movement of particles may be hindered, and if it is less than 10%, the contrast tends to be unclear.

In the image display device of the present invention, a plurality of display elements described above are used and arranged in a matrix for display. In the case of monochrome, one display element serves as one pixel. In the case of full color, three types of display elements, that is, display elements having R (red), G (green) and B (blue) color plates and each having black particles are set as one set,
It is preferable to arrange a plurality of them to form an image display device.

The image display device and the image display method of the present invention are used to display images of mobile devices such as laptop computers, PDAs, and mobile phones, billboards, posters, bulletin boards such as blackboards, copiers, calculators, and home appliances. It is used for departments.

[0029]

EXAMPLES Next, the present invention will be described more specifically by showing Examples and Comparative Examples. However, the present invention is not limited to the following examples. In each Example and Comparative Example, the average particle diameter d _0.5 and the surface charge density were measured as follows. (1) Average particle size d _0.5 (μm) Put each particle into a Mastersizer2000 (Malvern instruments Ltd.) measuring machine and use the attached analysis software (software for calculating particle size distribution and particle size based on volume standard distribution). The average particle diameter (μm) is defined as the numerical value in μm in which 50% of the particles are larger than 50% and smaller than 50%. (2) Surface charge density (μC / m ² ) As a blow-off powder charge amount measuring device, TB-200 manufactured by Toshiba Chemical Co., Ltd. was used. Two types of carriers, positively charged and negatively charged, were used, and the charge density per unit area (unit: μC / m ² ) in each case was measured. That is, F963-2535 manufactured by Powder Tech Co., Ltd. is used as a positively chargeable carrier (a carrier that makes a partner positively charged and is easily negatively charged by itself), and a negatively charged carrier (a partner is negatively charged and made positive by itself). As the carrier (which is easily charged), powder tech particles F921-2535 were used. The surface charge density was determined from the measured charge amount and the separately measured average particle diameter d _0.5 and specific gravity of the particles. The average particle diameter d _0.5 was measured by the method described above, and the specific gravity was measured by using a hydrometer manufactured by Shimadzu Corporation (trade name: Multi-Volume Densitometer H130).

Example 1 An image display device having a display element having the structure shown in FIG. 1 was produced. Using a glass substrate as a transparent substrate and a counter substrate,
The A and B electrodes were ITO electrodes, and the C and D electrodes were copper electrodes. As the negatively chargeable particles, a black polymerized toner for electrophotography (spherical particles having an average particle diameter d _0.5 8 μm, surface charge density −40 μC / m ² , the maximum surface potential value 450 V after 0.3 seconds of the surface potential measurement) was used. Using. The positively charged particles include black polymerized toner (average particle size d _{0.5 8} μ
m spherical shape, surface charge density +45 μC / m ² , maximum value of surface potential 480 after 0.3 seconds from the surface potential measurement
V) was used. The charging of the particles was carried out by triboelectrification by mixing both particles in equal amounts and stirring. The height of the partition wall was 200 μm, and the volume occupation rate of particles in the inter-substrate space was 50%. A red resin plate was used for the color filter. C
200V so that the electrode side is the negative electrode and the D electrode side is the positive electrode
When the DC voltage was applied, the positively chargeable particles flew and adhered to the C electrode side, and the negatively chargeable particles flew and moved to the D electrode side and adhered, and the display element was displayed in red. Next, when a DC voltage of 200 V is applied so that the C electrode and the D electrode are grounded, the A electrode side is the negative electrode, and the B electrode side is the positive electrode,
The positively chargeable particles flew to the A electrode side and adhered thereto, the negatively chargeable particles flew to the B electrode side and adhered thereto, and the display element was displayed in black. When the response time to voltage application was measured, it was 1 msec. In each display, the voltage application was stopped and left for 1 day, but the display was maintained. Next, the polarity reversal of the applied voltage was repeated 10,000 times, but there was almost no change in the response speed.

[0031]

According to the display element of the image display device of the present invention, particles having different charging characteristics are enclosed between two transparent substrates provided with a backlight, a color filter and two pairs of electrodes, and the space between the substrates is increased. An image is displayed by applying an electric field to particles to fly and move, but it has a fast response speed, a simple structure, excellent stability and sharpness, and is suitable for various image display boards and image display devices. Used.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a display element of an image display device of the present invention and a display operation principle thereof.

FIG. 2 is an explanatory diagram showing an example of a display element of the image display device of the present invention and a display operation principle thereof.

FIG. 3 is an explanatory diagram of a measuring device for measuring the surface potential of particles in the image display device of the present invention.

[Explanation of symbols]

1: Display substrate (transparent) 2: Counter substrate (transparent) 3: A electrode (transparent) 4: B electrode (transparent) 5: C electrode 6: D electrode 7: Negatively charged particles 8: Positively charged particles 9: Color filter 10: Backlight 11: Partition wall 12: Insulator 21: Chuck 22: Scorotron discharger 23: Surface electrometer

Continued front page    (72) Inventor Yakushiji Manabu             3-2- 6-408 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Hajime Kitano             3-5-5 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Yoshitomo Masuda             3-5-28 Shinmeidai, Hamura-shi, Tokyo (72) Inventor Takahiro Kawagoe             1302-57 Aobadai, Tokorozawa, Saitama Prefecture

Claims (9)

[Claims] 1. A particle having different charging characteristics is encapsulated between two transparent substrates provided with a backlight, a color filter and two pairs of electrodes, and an electric field is applied between the substrates to cause the particles to fly and move. An image display device for displaying an image. 2. The average particle diameter d _{0.5 of the} particles is 0.1 to 50.
The image display device according to claim 1, wherein the image display device has a thickness of μm. 3. The surface charge density of particles measured and calculated by a blow-off method using a carrier is 5 to 15 in absolute value.
The image display device according to claim 1, wherein the image display device has an amount of 0 μC / m ² . 4. The particles have a volume resistivity of 1 × 10 ¹⁰ Ω · cm.
The image display device according to claim 1, wherein the image display device comprises the above insulating particles. 5. When the particles are charged on the surface by applying a voltage of 8 kV to a corona discharger arranged at a distance of 1 mm from the surface to generate corona discharge,
The image display device according to claim 1, wherein the maximum value of the surface potential after 3 seconds is particles larger than 300V. 6. The image display device according to claim 1, wherein the color of the particles is black. 7. The image display device according to claim 1, further comprising one or more image display elements separated from each other by a partition wall. 8. A pair of electrodes, one of which is an electrode pair provided in a central portion of the substrate, and the other of which is an electrode pair provided in a peripheral portion and / or a partition of the substrate. Item 1
7. The image display device according to any one of 7. 9. An image display method using the image display device according to claim 1.