JP4862311B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device, and more specifically, an image that repeatedly displays images on an image display medium by moving charged particles enclosed between a display substrate and a back substrate of the image display medium by an electric field. The present invention relates to a display device.

  Conventionally, as an image display medium (display device) that can be repeatedly rewritten, it has Twisting Ball Display (two-color coating particle rotation display), an electrophoretic display medium, a magnetophoretic display medium, a thermal rewritable display medium, and a memory property. Liquid crystal display media have been proposed.

  Among these image display media, thermal rewritable display media and liquid crystal display media having memory properties are excellent in image memory properties, but the background cannot be made sufficiently white like paper. When an image is displayed, the contrast between the image portion and the non-image portion is small, and it is difficult to perform a clear display.

  A display medium using electrophoresis and magnetophoresis is known in which colored particles that can be moved by an electric field or a magnetic field are dispersed in a white liquid. The image portion is colored by attaching the colored particles to the display surface. The color of the particles is displayed, and in the non-image portion, the colored particles are removed from the display surface, and white is displayed by the white liquid to form an image. Since the movement of the colored particles does not occur without the action of an electric field or a magnetic field, it has a display memory property. However, in these methods, although white display property by the white liquid is excellent, when displaying the color of the colored particles, the white liquid enters the gap between the colored particles, so that the display density is lowered. Therefore, the contrast between the image portion and the non-image portion is reduced, and it is difficult to obtain a clear display. Further, since the white liquid is sealed in these display media, when the display medium is removed from the image display device and handled roughly like paper, the white liquid may leak from the display medium.

  Twisting Ball Display is a spherical particle whose half surface is painted white and the other surface is painted black by the action of an electric field. The display is performed by applying an electric field so as to be on the side. According to this, since the particles are not driven to rotate unless the electric field is applied, the display has a memory property. In the display medium, oil is present only in the cavities around the particles. However, since the display medium is mostly composed of solid, it is relatively easy to make the display medium into a sheet. However, in this method, it is difficult to completely rotate the particles, and the contrast is lowered by the particles that have not been completely rotated, so that it is difficult to form a clear display image. Also, even if the white-coated hemisphere is completely aligned on the display side, it is difficult to display white like paper due to light absorption and light scattering in the cavity, resulting in a clear display image. It was difficult to get. Furthermore, since the particle size is required to be smaller than the pixel size, fine spherical particles with different colors must be manufactured for high-resolution display, and advanced manufacturing technology is required. There is also a problem that it takes.

  Recently, a display medium having a configuration in which colored particles such as powder toner are enclosed between a pair of substrates has been proposed as a completely solid display medium (for example, see Patent Document 1).

  These have a structure in which conductive colored toner (for example, black toner) and insulating colored particles (for example, white particles) are encapsulated between a transparent display substrate and a rear substrate that is opposed to the transparent substrate. It has become. Electrodes are formed on the display substrate and the back substrate, and the inner surface of each substrate is coated with a charge transport material that transports only charges of one polarity (for example, holes). Between the display substrate and the rear substrate, a gap member is provided that holds a gap between the display substrate and the rear substrate and partitions the display substrate and the rear substrate into a plurality of cells.

  When a voltage is applied between these substrates, holes are injected only into the conductive black toner, the black toner is positively charged, and the white particles are pushed between the substrates according to the electric field formed between the substrates. Moving. Here, when the black toner is moved to the display substrate side, black display is performed, and when the black toner is moved to the rear substrate side, white display by white particles is performed. Therefore, a black and white image can be displayed by applying a voltage between the substrates according to the image information of the image to be displayed and moving the black toner.

  According to the display medium using these colored particles, the particles do not move unless an electric field is applied, so that the display has a memory property, and since the display medium is entirely made of solid, there is no problem of liquid leakage. . In addition, it is possible to perform image display with high contrast using two types of colored particles (for example, white particles and black particles).

Patent Document 2 has a configuration in which two types of colored particles having different colors and charging characteristics are enclosed between a transparent display substrate and a back substrate. It is charged with the polarity. Then, by applying an electric field between the display substrate and the back substrate, the two types of colored particle groups are moved to different substrate sides for display. In this display medium, if a voltage is applied between the substrates according to image information, a clear image display with high contrast can be performed.
JP 2001-3383 A JP 2000-165138 A

  However, in the above prior art, due to changes in environmental temperature, changes over time, repetitive rewriting, etc., the charge amount of the charged particle group enclosed between the substrates is reduced, and the charged particles are likely to adhere to the substrate. Or a phenomenon such as an increase in the adhesion between charged particles occurs. In such a state, when a display driving voltage for moving the particles to display an image on the image display medium is applied, the charged particle group is moved between the substrates due to a decrease in responsiveness according to the applied voltage of the charged particle group. There is a problem that a cell is generated in which the charged particles inside cannot move at all.

  As a method for coping with such a problem, a method of increasing the electrostatic force applied to the charged particles by increasing the voltage value of the display drive voltage and increasing the strength of the electric field formed between the opposing substrates can be considered. However, when the function for increasing the voltage value is provided in the image display device main body, there is a possibility that problems such as an increase in size and weight of the image display device main body may occur.

  The present invention has been made in view of the above-described facts, and an object of the present invention is to provide an image display device capable of easily moving between substrates of charged particles having reduced responsiveness between substrates with respect to an applied voltage. And

In order to achieve the above object, an image display device according to claim 1 of the present invention includes a display substrate having at least translucency, a back substrate disposed to face the display substrate with a gap, and the display. A first electrode comprising a plurality of electrodes provided on the substrate and arranged on the same plane parallel to the opposing surface of the display substrate and the back substrate, with at least a smaller interval than the gap between the display substrate and the back substrate. A plurality of electrodes arranged on the same plane parallel to the opposing surface of the rear substrate and the display substrate, with an interval smaller than at least the gap between the display substrate and the rear substrate. The display electrode according to an electric field formed by a voltage applied to the first electrode and the second electrode, and sealed between the display substrate and the back substrate. At least one type of charged particle group having different charging characteristics that can move between a plate and the back substrate, and a gap between the display substrate and the back substrate, and between the display substrate and the back substrate Before applying a display drive voltage for performing image display on the image display medium, and between the adjacent electrodes of the first electrode, A voltage whose potential difference between the adjacent electrodes is larger than a threshold voltage at which the charged particle group starts to move so that an electric field in which the charged particle group can move is generated in one or both of the adjacent electrodes of the second electrode. Voltage application means for applying a pre-driving voltage that makes a difference to one or both of the first electrode and the second electrode .

  The image display device according to claim 1 includes an image display medium, and the image display medium is charged between at least a translucent display substrate and a rear substrate facing the display substrate with a gap. When a display driving voltage is applied to each of the first electrode and the second electrode formed on each substrate by enclosing at least one kind of charged particle group having different characteristics, the first electrode and the second electrode The charged particles move between the substrates by the electric field formed between the second electrodes. The gap between the display substrate and the back substrate is held by a gap member that divides the display substrate and the back substrate into a plurality of cells. The display drive voltage generates an electric field that selectively moves at least one of the charged particle groups to either the display substrate or the back substrate in accordance with image information of an image to be displayed on the image display medium. Thus, the voltage applied to the first electrode and the second electrode. This display driving voltage is applied to the first electrode and the second electrode, and the charged particles move between the display substrate and the back substrate, whereby a desired image is displayed on the image display medium.

  Charged particles encapsulated between the display substrate and the back substrate are subject to a decrease in charge amount or adhesion between the substrate and charged particles due to changes in environmental temperature, changes over time, and repeated rewriting. Or a phenomenon such as an increase in adhesion between charged particles may occur. When such a phenomenon occurs, when a display driving voltage is applied to the first electrode and the second electrode in order to display an image on the image display medium, the responsiveness corresponding to the applied voltage of the charged particle group decreases. However, there is a problem in that a cell in which the charged particle group does not move at all even when a voltage is applied is generated.

Accordingly, the voltage application means applies the display drive voltage for displaying an image to the image display medium between adjacent electrodes of the first electrode (arrangement direction of the plurality of electrodes of the first electrode) and the second. The charged particle group is moved by the potential difference between the adjacent electrodes so that an electric field that allows the charged particle group to move is generated between any one or both of the adjacent electrodes (the arrangement direction of the plurality of electrodes of the second electrode). A voltage is applied to one or both of the first electrode and the second electrode with a pre-driving voltage such that the voltage difference is larger than the threshold voltage for starting the operation .

  In this way, the first electric field is generated such that an electric field capable of moving the charged particle group is generated in one or both of the arrangement direction of the plurality of electrodes of the first electrode and the arrangement direction of the plurality of electrodes of the second electrode. After applying the preliminary driving voltage to one or both of the first electrode and the second electrode, and then applying the display driving voltage, one of the first electrode and the second electrode is applied by applying the preliminary driving voltage. Alternatively, the group of charged particles moved in both arrangement directions can be moved between the display substrate and the back substrate by an electric field formed by applying a display driving voltage. Therefore, the display drive voltage can be applied after the charged particle group is easily moved in the electrode arrangement direction in which the charged particle group is more easily moved than between the substrates, and the charged particle group is in the electrode arrangement direction. A voltage can be applied so as to move between the substrates triggered by the movement to the.

  Therefore, the charged particles having reduced responsiveness between the substrates with respect to the applied voltage can be easily moved between the substrates.

An image display device according to a second aspect is the image display device according to the first aspect, wherein the voltage applying means is arranged via one electrode or a plurality of electrodes in the arrangement direction of the first electrode or the second electrode. Thus, the preliminary driving voltage can be applied .

  For this reason, it is possible to easily move between the substrates with respect to the charged particles whose responsiveness between the substrates with respect to the applied voltage is lowered.

  The image display device according to claim 3 is the image display device according to claim 1 or 2, wherein the preliminary drive voltage is an alternating voltage, and the arrangement direction of the first electrode and the second electrode The charged particle group can be easily moved in either or both of the arrangement directions.

  The image display device according to claim 4 is the image display device according to any one of claims 1 to 3, wherein the voltage application unit is configured to apply the first electrode when the preliminary drive voltage is applied. The first electrode and the second electrode so that an electric field capable of moving the charged particle group is generated in one or both of the arrangement direction of the plurality of electrodes and the arrangement direction of the plurality of electrodes of the second electrode. After applying a voltage to one or both of the electrodes, the first electrode and the second electrode are generated so that an electric field is generated in which the charged particle group can move between the display substrate and the back substrate. A DC voltage can be applied to the electrodes.

  The image display device according to claim 5 is the image display device according to any one of claims 1 to 4, wherein the voltage application unit is configured to apply the first drive voltage when the preliminary drive voltage is applied. The first electrode and the first electrode and the second electrode so that an electric field capable of moving the charged particle group is generated in one or both of the arrangement direction of the plurality of electrodes and the arrangement direction of the plurality of electrodes of the second electrode. After applying a voltage to one or both of the second electrodes, the first electrode and the first electrode are generated so that an electric field that allows the charged particle group to move between the display substrate and the back substrate is generated. An alternating voltage can be applied to the two electrodes.

  In the image display device according to any one of claims 4 and 5, the preliminary drive voltage may be applied to one or both of the arrangement direction of the plurality of electrodes of the first electrode and the arrangement direction of the plurality of electrodes of the second electrode. The charged particle group can move between the display substrate and the back substrate after applying a voltage to one or both of the first electrode and the second electrode so that an electric field capable of moving the charged particle group is generated. Since an alternating voltage or a DC voltage is applied to the first electrode and the second electrode so as to generate an electric field, the charged particles can be further moved when the preliminary driving voltage is applied.

  The image display device according to claim 6 is the image display device according to any one of claims 1 to 5, wherein the charged particle groups are two or more types of charged particle groups having different charging characteristics. be able to. As described above, when the charged particle groups are two or more types of charged particle groups having different charging characteristics, when a preliminary driving voltage is applied, the charged particle groups having different charging characteristics collide with each other with respect to the applied voltage. The movement of the charged particles with reduced responsiveness can be promoted, and the charged particles with reduced responsiveness between the substrates with respect to the applied voltage can be easily moved between the substrates.

  The image display device according to claim 7 is the image display device according to any one of claims 1 to 6, wherein the image display medium includes the first electrode and the second electrode. Each of the image display media may be a simple matrix image display medium that is configured of an electrode group including a plurality of line-shaped electrodes and is disposed so as to be orthogonal to the first electrode and the second electrode. .

  The image display device according to claim 8 is the image display device according to any one of claims 1 to 6, wherein the image display medium includes at least the second electrode for each pixel. It may be an active matrix image display medium composed of a plurality of electrode groups.

  As described above, according to the present invention, before applying the display drive voltage for performing image display on the image display medium, as the preliminary drive voltage, the arrangement direction of the plurality of electrodes of the first electrode and the Either or both of the first electrode and the second electrode so that an electric field capable of moving the charged particle group is generated in one or both of the arrangement directions of the plurality of electrodes of the second electrode. Since the display drive voltage is applied after the charged particles are easily moved in the direction in which the particles are more likely to move from one substrate to the other because the voltage is applied to the charged particles. In addition, an image display device that can be easily moved between the substrates can be provided.

  Embodiments of the image display apparatus according to the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the image display device 10 includes an image display medium 12 and a voltage application unit 14. The image display medium 12 is a medium for displaying an image, and the voltage application unit 14 selectively applies a voltage to the image display medium 12 according to image information.

  The image display medium 12 includes a transparent display substrate 16 provided on the viewing side X, a transparent rear substrate 18 that faces the display substrate 16 with a gap, and holds the substrates at a predetermined interval. A gap member 20 that divides the substrate 18 into a plurality of cells and a group of charged particles 25 enclosed between the substrates are formed.

  The display substrate 16 has a configuration in which a line electrode 28 and an insulating layer 30 are laminated on a transparent support substrate (or glass substrate) 26. The line-shaped electrode 28 is formed in a plurality of lines by an ITO conductive film, and is provided for each pixel column in a predetermined direction of a display image displayed on the image display medium 12. In the image display medium 12 shown in FIG. 1, the line electrodes 28 are arranged in the column direction, and are hereinafter referred to as column electrodes 28.

  An interval between adjacent electrodes of the column electrode 28 is provided so as to be narrower than at least the interval between the display substrate 16 and the back substrate 18. Note that a plurality of column electrodes 28 may be provided for one pixel column of the display image.

  The back substrate 18 has a structure in which a support substrate 32, a line electrode 34, and an insulating layer 38 are laminated. The line electrodes 34 are formed on the support substrate 32 so as to form a plurality of lines using copper electrodes or the like, and are provided for each pixel column in a direction orthogonal to the column electrodes 28 formed on the display substrate 16. Yes. Hereinafter, it is referred to as a row electrode 34.

  Similar to the column electrode 28, the adjacent electrode interval of the row electrode 34 is provided to be narrower than at least the interval between the display substrate 16 and the back substrate 18.

The gap member 20 is formed so as not to impair the transparency of the display substrate 16 and holds the gap between the display substrate 16 and the back substrate 18. The gap member 20 may be formed so as to divide the display area of the image display medium 12 for each pixel of the image displayed on the image display medium 12, but a plurality of pixels in terms of the aperture ratio contributing to image display. It is preferable to form the display area of the image display medium 12 so as to divide the display area every time.

  In the present embodiment, the charged particle group 25 includes white particles 22 and black particles 24 having different charging characteristics.

  The white particles 22 and the black particles 24 are particle groups having different charging characteristics. Specifically, the white particles 22 and the black particles 24 are charged and sealed so as to have opposite polarities (one is positive and the other is negative). . In the present embodiment, in order to simplify the description, it is assumed that the black particles 24 are positively charged and the white particles 22 are negatively charged.

  The display substrate 16 corresponds to the display substrate of the present invention, the back substrate 18 corresponds to the back substrate of the present invention, and the white particles 22 and the black particles 24 (charged particle group 25) correspond to the charged particle group of the present invention. To do. The image display medium 12 corresponds to the image display medium of the present invention, and the line electrode (column electrode) 28 and the line electrode (row electrode) 34 respectively serve as the first electrode and the second electrode of the present invention. The voltage application unit 14 corresponds to each of the voltage application means of the present invention.

  FIG. 2 is a block diagram showing an electrical configuration of the image display apparatus 10 according to the present embodiment. In the present embodiment, it is assumed that the region where the column electrode 28 and the row electrode 34 face each other is one pixel, and the gap member 20 is provided so that one cell is configured by 2 × 3 pixels. However, the arrangement is not limited to this.

  The image display medium 12 has a simple matrix drive system configuration in which the column electrodes 28 formed on the display substrate 16 and the row electrodes 34 formed on the back substrate 18 are arranged so as to intersect each other. Although not shown, the column electrode 28 and the row electrode 34 are formed on each substrate with the number of electrodes corresponding to the number of vertical and horizontal pixels necessary for image display.

  The voltage application unit 14 includes a column electrode drive circuit 40, a row electrode drive circuit 42, a sequencer 44, an external power supply 46, and an image input device 48. The column electrode 28 is connected to the column electrode drive circuit 40. The row electrode 34 is connected to the row electrode drive circuit 42. The column electrode drive circuit 40 and the row electrode drive circuit 42 are connected to a sequencer 44 and an external power supply 46. The sequencer 44 is connected to the image input device 48 and outputs a signal to the column electrode drive circuit 40 and the row electrode drive circuit 42 in accordance with image information input from the image input device 48.

  In such an image display device 10, an image write signal (scanning signal) for each row electrode 34 is sent from the sequencer 44 to the row electrode drive circuit 42, and a display drive voltage (hereinafter referred to as a display drive voltage) is applied from the row electrode drive circuit 42 to the row electrode 34. , Referred to as scanning voltage). At the same time, an image information signal corresponding to the row electrode 34 to which the scanning voltage is applied is sent from the sequencer 44 to the column electrode driving circuit 40 in synchronization with the application of the scanning voltage sequentially applied to the row electrode 34. The column electrode drive circuit 40 applies a display drive voltage corresponding to image information to the column electrodes 28 all at once. The scanning direction of the scanning voltage applied to the row electrode 34 is the arrow Z direction. Similarly, a desired image can be displayed on the image display medium 12 by sequentially applying a voltage in the scanning direction Z.

In the present embodiment, a 6 × 6 simple matrix configuration is used for simplification of description, and the six column electrodes 28 of the display substrate 16 are 28a, 28b, 28c, 28d, 28e, and 28f, respectively. The row electrodes 34 of the substrate 18 were 34i, 34ii, 34iii, 34iv, 34v, and 34vi, respectively. Actually, it goes without saying that the number of electrodes corresponding to the number of vertical and horizontal pixels necessary for image display is formed on each substrate (the display substrate 16 and the back substrate 18). In the present embodiment, the line-shaped electrode 28 of the display substrate 16 is a column electrode and the line-shaped electrode 34 of the back substrate 18 forms a row electrode. A configuration in which row electrodes are provided on the substrate 16 and column electrodes are provided on the back substrate 18 may be employed.

  (Method for manufacturing image display medium)

  In this embodiment, a transparent conductive ITO supporting substrate of 70 mm × 50 mm × 1.1 mm is used as the display substrate 16 of the image display medium 12, and a width of 0.234 mm and a spacing of 0. A plurality of 02 mm line-shaped column electrodes 28 were formed. Similarly, the back substrate 18 uses a 70 mm × 50 mm × 1.1 mm ITO supporting substrate, and a plurality of line-shaped row electrodes 34 having a width of 0.234 mm and a spacing of 0.02 mm are formed on the supporting substrate 32 by etching. did. The insulating layer 30 and the insulating layer 38 were formed on the opposing surfaces of the display substrate 16 and the back substrate 18 by applying a transparent polycarbonate resin to a thickness of about 1 μm, respectively.

  A gap member 20 was provided between the display substrate 16 and the back substrate 18 so as to have a height of 100 μm.

  The gap member 20 was formed by applying a thermosetting epoxy resin to the rear substrate 18 in a desired pattern shape by screen printing, heating and curing this, and repeating this process until the required height was reached. . The cell pattern formed by the gap member 20 was formed such that rectangular cells having a length of 1 mm and a width of 4 mm were arranged in a brick shape. The gap member 20 can also be formed by adhering a thermoplastic film formed in a desired surface shape to the back substrate 18 by injection compression molding, embossing, hot pressing, or the like. Further, the gap member 20 can be integrally formed with the back substrate 18 by embossing or hot pressing. Of course, the gap member 20 may be formed on the display substrate 16 side or may be integrally formed with the display substrate 16 as long as the transparency is not impaired.

  The charged particle group 25 includes spherical black particles 24 of carbon-containing crosslinked polymethylmethacrylate having a volume average primary particle size of 10 μm obtained by mixing Aerosil A130 fine powder treated with aminopropyltrimethoxysilane at a weight ratio of 100 to 0.2. Sekisui Plastics Co., Ltd. Techpolymer MBX-Black) and titania fine powder treated with isopropyltrimethoxysilane mixed at a weight ratio of 100 to 0.1 containing titanium oxide with a volume average primary particle size of 10 μm Spherical white particles 22 of cross-linked polymethylmethacrylate (Techpolymer MBX-white manufactured by Sekisui Plastics Co., Ltd.) were used, and these were mixed at a weight ratio of 3 to 5. At this time, the black particles 24 were positively charged and the white particles 22 were negatively charged by mutual friction.

  About 12 mg of the mixed particles of the black particles 24 and the white particles 22 were shaken out evenly through the screen in the space between the gap member 20 and the gap member 20 on the back substrate 18. Then, the display substrate 16 is stacked on the rear substrate 18 via the gap member 20 so that the line-shaped row electrodes 34 of the rear substrate 18 and the line-shaped column electrodes 28 of the display substrate 16 are orthogonal to each other. Was pressed and held with a double clip, and the gap member 20 and both substrates were brought into close contact with each other to form the image display medium 12. The total volume ratio of the white particles 22 and the black particles 24 to the void volume between the substrates was about 20%.

  As shown in FIG. 2, the image display medium 12 created as described above has the column electrode 28 of the display substrate 16 as the column electrode drive circuit 40, and the row electrode 34 of the back substrate 18 as the row electrode drive circuit 42. The image display device 10 was manufactured by connecting so that signals could be exchanged.

  The mixing ratio of the white particles 22 and the black particles 24, the total volume ratio of the white particles 22 and the black particles 24 to the void volume between the substrates, and the volume average primary particle size of each particle are not limited to the above values. .

  In addition, as the charged particle group 25 that can be used in the image display device 10 of the present invention, and the display substrate 16 and the back substrate 18, the following charged particles and the following substrate can be used.

  (Charged particles)

  As the charged particle group 25 that can be used in the present embodiment, in addition to the charged particle group 25 described above, insulating metal oxide particles such as glass beads, alumina, and titanium oxide, and thermoplastic or thermosetting resins can be used. Examples thereof include particles, those obtained by fixing a colorant on the surface of these resin particles, and particles containing an insulating colorant in a thermoplastic or thermosetting resin.

  Examples of the thermoplastic resin used in the production of the charged particle group 25 include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate. Α-methylene fat such as vinyl ester such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers of aromatic monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl butyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone It can be exemplified a copolymer.

  In addition, as the thermosetting resin used for the production of the charged particle group 25, cross-linked resins mainly composed of divinylbenzene, cross-linked resins such as cross-linked polymethyl methacrylate, phenol resins, urea resins, melamine resins, polyesters Examples thereof include a resin and a silicone resin. Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include a polymer, polyethylene, polypropylene, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, and paraffin wax.

  As the colorant, organic or inorganic pigments, oil-soluble dyes, etc. can be used, magnetic powders such as magnetite and ferrite, carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan colorant, Known colorants such as an azo yellow color material, an azo magenta color material, a quinacridone magenta color material, a red color material, a green color material, and a blue color material can be given. Specifically, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3, etc. can be exemplified as typical ones. Further, porous sponge-like particles or hollow particles enclosing air can be used as the white particles 22. These are selected so that the two types of particles have different color tones.

  The shape of the charged particle group 25 is not particularly limited, but a spherical particle having a small physical adhesion to the charged particle group 25 and the display substrate 16 and the back substrate 18 and good particle fluidity is preferable. In order to form spherical particles, suspension polymerization, emulsion polymerization, dispersion polymerization or the like can be used.

  The volume average primary particle size of the charged particle group 25 is generally 1 to 1000 μm, preferably 5 to 50 μm, but is not limited thereto.

  An external additive may be attached to the surface of the charged particle group 25 as necessary. By attaching the external additive, the charging characteristics of the charged particle group 25 can be controlled and the fluidity can be improved. The color of the external additive is preferably white or transparent so as not to affect the color of the charged particle group 25.

  As the external additive, inorganic fine particles such as metal oxides such as silicon oxide (silica), titanium oxide, and alumina are used. In order to adjust the chargeability, fluidity, environment dependency, etc. of the fine particles, these can be surface-treated with a coupling agent or silicone oil.

  Coupling agents include positively chargeable ones such as aminosilane coupling agents, aminotitanium coupling agents, nitrile coupling agents, and silanes that do not contain nitrogen atoms (consisting of atoms other than nitrogen). There are negatively charged ones such as coupling agents, titanium-based coupling agents, epoxy silane coupling agents, and acrylic silane coupling agents. Similarly, silicone oil includes positively chargeable ones such as amino-modified silicone oil, dimethyl silicone oil, alkyl-modified silicone oil, α-methylsulfone-modified silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, fluorine-modified. Examples include negatively chargeable ones such as silicone oil. These are selected according to the desired resistance of the external additive.

Of these external additives, well-known hydrophobic silica and hydrophobic titanium oxide are preferable. In particular, TiO (OH) ₂ described in JP-A-10-3177 and a silane compound such as a silane coupling agent. The titanium compound obtained by the reaction with is suitable. As the silane compound, any of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. This titanium compound is produced by reacting TiO (OH) ₂ produced in a wet process with a silane compound or silicone oil and drying it. Since it does not pass through the firing step of several hundred degrees, strong bonds between Ti are not formed, there is no aggregation, and the fine particles are almost in the state of primary particles. Furthermore, since the silane compound or silicone oil reacts directly with TiO (OH) ₂ , the amount of silane compound or silicone oil treated can be increased, and the charging characteristics can be controlled by adjusting the amount of silane compound treated. The charging ability that can be imparted and can be imparted can be significantly improved over that of conventional titanium oxide.

  The volume average primary particle size of the external additive is generally 5 to 100 nm, preferably 10 to 50 nm, but is not limited thereto.

  The mixing ratio of the external additive and the charged particle group 25 is appropriately adjusted based on the balance between the particle size of the particle and the particle size of the external additive. If the added amount of the external additive is too large, a part of the external additive is liberated from the surface of the charged particle group 25 and adheres to the surface of the other particle, so that desired charging characteristics may not be obtained. Generally, the amount of the external additive is 0.01 to 3 parts by mass, more preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the charged particles.

  The composition of the charged particle group 25 to be combined, the mixing ratio of the particles, the presence or absence of the external additive, the composition of the external additive, and the like are selected so that the desired charging characteristics can be obtained.

  The external additive may be added to only one of the two types of particles, or may be added to both charged particle groups 25. When adding an external additive to both particles, it is preferable to use external additives having different polarities. In addition, when an external additive is added to the surfaces of both particles, the external additive is applied to the surface of the charged particle group 25 by impact force, or the surface of the charged particle group 25 is heated to apply the external additive to the particle surface. It is desirable to fix firmly. Thereby, the external additive is released from the charged particle group 25, and the external additive of different polarity is strongly aggregated to prevent formation of an aggregate of the external additive that is difficult to dissociate with an electric field, As a result, image quality deterioration is prevented.

  The contrast depends not only on the primary average volume particle diameter of the two types of charged particle groups 25 but also on the mixing ratio of these charged particle groups 25. In order to obtain high contrast, it is desirable to determine the mixing ratio so that the surface areas of the two types of charged particle groups 25 are the same. If the ratio deviates greatly from this ratio, the color of particles having a large ratio is emphasized. However, this is not the case when the color tone of the two types of charged particle groups 25 is changed to a dark color tone and a light color tone of similar colors, or when the color produced by mixing the two types of charged particle groups 25 is used for an image.

(Display board / Back board)

  Next, the support substrate that can be used as each of the display substrate 16 and the back substrate 18 of the present embodiment can be composed of a general support substrate and electrodes. Examples of the support substrate 26 and the support substrate 32 include glass and plastics such as polycarbonate resin, acrylic resin, polyimide resin, polyester resin, and epoxy resin. For the electrodes, use oxides such as indium, tin, cadmium and antimony, composite oxides such as ITO, metals such as gold, silver, copper and nickel, organic conductive materials such as polypyrrole and polythiophene, etc. Can do. These can be used as a single layer film, a mixed film, or a composite film, and can be formed by vapor deposition, sputtering, coating, or the like. The thickness is usually 100 to 2000 angstroms according to the vapor deposition method and the sputtering method. The row electrodes 34 and the column electrodes 28 can be formed in a desired pattern, for example, a matrix shape, by a conventionally known means such as etching of a conventional liquid crystal display element or a printed board.

  The row electrodes 34 and the column electrodes 28 may be embedded in the display substrate 16 and the back substrate 18 respectively. In this case, the materials of the display substrate 16 and the back substrate 18 also serve as dielectric layers, and charged particles. Since the charging characteristics and fluidity of the group 25 may be affected, it is necessary to select appropriately according to the composition of the charged particle group 25 and the like.

  Further, the column electrodes 28 and the row electrodes 34 may be arranged outside the image display medium 12 separately from the display substrate 16 and the back substrate 18 respectively.

  In the case where the column electrode 28 and the row electrode 34 are formed on the display substrate 16 and the back substrate 18 respectively, in order to prevent the occurrence of leakage between the electrodes causing damage to the electrodes and fixation of the charged particle group 25, If necessary, a dielectric film may be formed as the insulating layer 30 and the insulating layer 38 on the electrodes (column electrode 28 and row electrode 34). As the dielectric film, polycarbonate, polyester, polystyrene, polyimide, epoxy, polyisocyanate, polyamide, polyvinyl alcohol, polybutadiene, polymethyl methacrylate, copolymerized nylon, ultraviolet curable acrylic resin, fluorine resin, or the like can be used.

  In addition to the insulating material described above, an insulating material containing a charge transport material can also be used. By containing a charge transport material, the chargeability of the charged particle group 25 can be improved by improving the chargeability of the particle by injecting the charge into the charged particle group 25 or when the charged amount of the charged particle group 25 becomes extremely large. Effects such as stabilizing the charge amount of the charged particle group 25 can be obtained. Examples of the charge transport material include a hydrazone compound, a stilbene compound, a pyrazoline compound, and an arylamine compound that are hole transport materials. Further, a fluorenone compound, a diphenoquinone derivative, a pyran compound, zinc oxide, or the like, which is an electron transport material, can also be used. Furthermore, a self-supporting resin having a charge transporting property can also be used. Specific examples thereof include polyvinyl carbazole and polycarbonate obtained by polymerization of a specific dihydroxyarylamine and bischloroformate described in US Pat. No. 4,806,443.

  Since the dielectric film affects the charging characteristics and fluidity of the charged particle group 25, it is appropriately selected according to the composition of the charged particle group 25 and the like. Since the display substrate 16 which is one of the substrates needs to transmit light, it is preferable to use a transparent one of the above materials.

  (Display drive voltage)

  First, an operation when a display drive voltage applied when displaying an image on the image display medium is applied to the image display medium 12 will be described.

  The display drive voltage is a voltage applied to the column electrode 28 and the row electrode 34 when an image corresponding to the image information input from the image input device 48 is displayed on the image display medium 12, and is selectively applied to the column. One kind (white particles 22 or black particles 24) of the charged particles 25 enclosed in the corresponding region is displayed on the display substrate by an electric field formed by applying a voltage to the electrodes 28 and the row electrodes 34. 16 and a voltage for selectively moving to one of the back substrate 18 and the back substrate 18.

Here, an example in which a black image is displayed on a white display surface by a simple matrix driving method will be described. In the following description, the display drive voltage applied to the column electrode 28 of the display substrate 16 according to the image information signal is V _SB , and the display drive voltage applied sequentially to the row electrode 34 of the back substrate 18 is V _LB. In addition, all the electrodes on which no image is written are assumed to be 0 V or grounded.

2, that is, a region where the column electrode and the row electrode intersect, a region where the row electrode 34i and the column electrode 28a intersect, a region where the row electrode 34i and the column electrode 28c intersect, and the row electrode. 34ii and the column electrode 28b intersect, the row electrode 34ii and the column electrode 28d intersect, the row electrode 34iii and the column electrode 28a intersect, and the row electrode 34iii and the column electrode 28c intersect When the pixel corresponding to each region is changed from white display to black display, display drive is performed on the row electrode 34i of the back substrate 18 in order to display an image of the pixel in the i-th row (corresponding to the row electrode 34i). The voltage V _LB is applied, and the display drive voltage V _SB is applied to the column electrode 28 a and the column electrode 28 c of the display substrate 16 in synchronization with the voltage V _LB. Next, in order to display an image of the pixel in the ii-th row (corresponding to the row electrode 34ii), the voltage V _LB is applied to the ii-th row (row electrode 34ii) of the rear substrate 18, and the display substrate is synchronized with this. The display drive voltage V _SB is applied to the 16 b columns (column electrode 28b) and d column (column electrode 28d). Then (corresponding to the row electrodes 34Iii) iii row to display an image of the pixel, the voltage V _LB are applied to iii row of the rear substrate 18 (the row electrodes 34Iii), the display substrate 16 in synchronism with The voltage V _SB is applied to the a column (column electrode 28a) and the c column (column electrode 28c).

Therefore, | V _SB −V _LB | / d ₁ acts as a display drive electric field on the pixel that changes from white display to black display. The (d ₁ is the distance between the substrates), in the pixel is not performed black display remains white display | for driving electric field / d ₁ will act, | | V _SB | / d ₁ or | V _LB V _SB Even if | / d ₁ or | V _LB | / d ₁ acts, it is necessary that the display does not change, that is, the particles do not move between the substrates. Therefore, V _SB and V _LB are set as follows.

FIG. 3 shows the relationship between the electric field intensity applied between the display substrate 16 and the back substrate 18 and the image display density (reflection density) in the image display medium 12 used in the present embodiment. This is an example of an image display medium that changes from black display to white display with a positive electric field and changes from white display to black display with a negative electric field. According to FIG. 3, the display density changes according to the electric field strength, and the higher the electric field strength, the higher the display contrast. Further, it can be seen that there is an electric field region in which the particles do not move up to the positive electric field strength E ₁ or the negative electric field strength E ₁ ′ and the display density does not change. Therefore, in this image display medium 12, in order to obtain a higher display contrast by simple matrix driving, it is necessary to increase | V _SB −V _LB | / d ₁ as much as possible and | V _SB | / d ₁ or In order to prevent the display from changing even when | V _LB | / d ₁ is applied, V _SB and V _LB are set to a threshold voltage value at which the particles start to move between the substrates.

Similarly, when a white image is displayed on the black display surface by simple matrix driving, the display drive voltage applied to the column electrode 28 of the display substrate 16 according to the image information signal is V _SW , and the row electrode of the rear substrate 18 is used. Assuming that the display drive voltage applied to 34 is V _LW , a display drive electric field of | V _SW −V _LW | / d ₁ acts on a pixel that changes from white display to black display, but white display is not performed while black display is performed. A driving electric field of | V _SW | / d ₁ or | V _LW | / d ₁ is also applied to the pixel. Therefore, as described above, in order to obtain a higher display contrast, it is necessary to increase | V _SW −V _LW | / d ₁ as much as possible, and V _SW and V _LW are the last minute particles start to move. A voltage value, that is, a threshold voltage is set.

  In this embodiment, the row electrode 34 and the column electrode 28 on which no image is written are set to 0 V or ground. However, as described above, in the pixel corresponding to the non-image portion, particles do not move unnecessarily between the substrates, and the image An arbitrary voltage may be applied to the row electrode 34 and the column electrode 28 on which no image is written as long as the condition that display is possible in the portion is satisfied.

Here, due to changes in environmental temperature, changes with time, repeated rewrites, etc., the charge amount of the charged particle group 25 enclosed between the substrates is reduced, or the display substrate 16 or the back substrate 18 and the charged particle group. When the phenomenon such that the adhesion between the charged particle groups 25 or the charged particle groups 25 is increased occurs, the charged particle groups 25 are moved to one of the substrates to display an image on the image display medium 12. When a display driving voltage for forming an electric field is applied so as to selectively move, the charged particle group 25 may not be driven at all due to a decrease in responsiveness corresponding to the applied voltage of the charged particle group 25.
That is, the charge amount of the charged particles group, the strength of the adhesion between the substrate and the charged particles, and the strength of the adhesion between the charged particles do not change uniformly. There is a problem that a cell in which particles cannot move at all occurs.

  For this reason, in the image display device 10 of the present invention, before applying the display drive voltage, the arrangement direction of the row electrodes 34 provided on the back substrate 18 and the column electrode 28 provided on the display substrate 16 are used as a preliminary drive voltage. A voltage is applied to one or both of the row electrode 34 and the column electrode 28 so that an electric field in which the charged particle group 25 can move is generated in either or both of the arrangement directions.

  Specifically, as the pre-driving voltage, as shown in FIG. 4A, a charged particle group 25 is provided between adjacent electrodes of the row electrode 34 and the column electrode 28 provided on each of the back substrate 18 and the display substrate 16. A voltage is applied so that a potential difference that can move is generated.

  As the preliminary drive voltage, as shown in FIG. 4B, the row electrode 34 and the column electrode 28 provided on each of the back substrate 18 and the display substrate 16 are provided for each electrode via a plurality of electrodes. A voltage may be applied. Specifically, the voltage may be applied every one electrode or every two electrodes. In this case, the distance between the electrodes to which the voltage is applied may be narrower than the distance between the back substrate 18 and the display substrate 16.

  As shown in FIGS. 5A and 5B, the preliminary drive voltage is applied to either the row electrode 34 provided on the back substrate 18 or the column electrode 28 provided on the display substrate 16. It may be possible to apply only.

  Further, as shown in FIG. 6, as a preliminary drive voltage, a charged particle group 25 is provided between any one of adjacent electrodes of the row electrode 34 provided on the back substrate 18 and the column electrode 28 provided on the display substrate 16. Simultaneously or immediately after applying a voltage so as to generate a movable potential difference, a voltage is applied to all of the electrodes provided on the other substrate, and a DC voltage or an alternating voltage is applied between the back substrate 18 and the display substrate 16. A voltage may be applied.

As the preliminary drive voltage, a threshold value that is an electron difference at which the charged particle group 25 starts to move between the electrodes to which the preliminary drive voltage of one or both of the row electrode 34 and the column electrode 28 is applied. A voltage value larger than the voltage and not more than a predetermined maximum voltage value may be applied.
The maximum voltage value is determined by the driver IC used in the image display apparatus 10. Normally, a driver IC that can sufficiently apply a display drive voltage is selected. Therefore, the maximum voltage value that can be applied determined by the driver IC is larger than the voltage value used as the display drive voltage. For this reason, it is effective to use the maximum voltage value that can be applied as determined by the driver IC as the initialization drive voltage and the preliminary drive voltage.

  In the method of applying the preliminary driving voltage, when the column electrode 28 on the display substrate 16 side is used as a scanning electrode, the row electrode 34 on the rear substrate 18 side is used as a data electrode, and a preliminary driving voltage is applied between adjacent electrodes of the row electrode 34. The deterioration of the image quality of the display image due to the uneven distribution of the charged particle group 25 due to the movement of the charged particle group 25 between the electrodes can be suppressed, which is preferable.

  As described above, a plurality of row electrodes 34 on the display substrate 16 and a plurality of column electrodes 28 on the back substrate 18 are arranged so as to be narrower than the interval between the display substrate 16 and the back substrate 18, and used as a preliminary drive voltage. The electric field in which the charged particle group 25 can move is generated in one or both of the arrangement direction of the row electrodes 34 provided on the back substrate 18 and the arrangement direction of the column electrodes 28 provided on the display substrate 16. When a voltage is applied to one or both of the row electrode 34 and the column electrode 28, the column electrode 28 and the display electrode are applied even when a voltage having the same voltage value as the display drive voltage is applied when the preliminary drive voltage is applied. The electric field strength formed between the plurality of electrodes of the column electrode 28 and between the plurality of electrodes of the row electrode 34 is larger than the electric field strength formed between the row electrodes 34.

  In general, the gap between the display substrate 16 and the back substrate 18 is required to be 30 μm or more so that the charged particle group 25 can sufficiently move between the substrates. For example, if it is manufactured by a photolithography method, it can be set to 20 μm or less. Therefore, even when a voltage having the same voltage value as the display driving voltage is applied when the preliminary driving voltage is applied, the column electrode 28 and the row electrode 34 are used. The electric field strength formed between the plurality of electrodes of the column electrode 28 and between the plurality of electrodes of the row electrode 34 is several times to ten times as large as the electric field strength formed therebetween.

  That is, when a voltage is applied between electrodes (between a plurality of electrodes of the column electrode 28 and a plurality of electrodes of the row electrode 34) formed on the same substrate, the charged particles are at a voltage equal to or lower than the voltage value of the display drive voltage. Charged particles that can form a sufficient electric field for moving the group 25 in the arrangement direction of the electrodes, and have reduced responsiveness due to adhesion to the substrate, adhesion between the charged particle groups 25, deterioration of charging characteristics, etc. The group 25 can be easily moved in the direction in which the row electrode 34 and the column electrode 28 are arranged.

  As described above, if the display drive voltage is applied after the charged particle group 25 having reduced responsiveness is moved by applying the preliminary drive voltage, the movement of the charged particle group 25 by applying the preliminary drive voltage is a trigger. The entire charged particle group 25 enclosed between the display substrate 16 and the back substrate 18 can be easily moved between the substrates.

  Further, as shown in FIG. 7, when the charged particle group 25 is a spherical particle or a particle close to a sphere, the spherical particles are separated from the display substrate 16 and the back substrate 18 and moved away from the display substrate 16 and the rear substrate 18. 16 and the rear substrate 18 are moved in a direction along the opposing surfaces with a smaller force. For this reason, if the charged particle group 25 (white particles 22 and black particles 24) is a spherical particle having a small physical adhesion to the display substrate 16 and the back substrate 18 and good fluidity of the particles, The charged particle group 25 whose responsiveness is easily lowered can be moved in the arrangement direction of the row electrode 34 or the column electrode 28.

Note that the preliminary drive voltage may be a DC voltage or an alternating voltage. When the alternating voltage is used, the particles reciprocate between the electrodes to which the preliminary driving voltage is applied. Therefore, the charged particle group 25 is more reliably applied to the row electrode 34 or the column electrode 28 by applying the preliminary driving voltage. Can be moved to.
Further, as shown in FIG. 6, as a preliminary drive voltage, a charged particle group 25 is provided between any one of adjacent electrodes of the row electrode 34 provided on the back substrate 18 and the column electrode 28 provided on the display substrate 16. At the same time as or after the voltage is applied so that a movable potential difference is generated, the voltage is applied to all the electrodes provided on the other substrate, and a DC voltage or an alternating voltage is applied between the back substrate 18 and the display substrate 16. Is applied, the entire charged particle group 25 can be easily moved between the substrates.

  Next, processing executed by the voltage application unit 14 of the image display device 10 of the present invention will be described.

  The voltage application unit 14 executes the processing routine shown in FIG. 8 every predetermined time, and proceeds to step 100 to determine whether to display an image on the image display medium 12. If the determination is affirmative, the image display medium 12 is erased by applying a voltage to the column electrode 28 and the row electrode 34 so as to display black or white on the entire surface of the image display medium 12. After performing the processing, the process proceeds to step 102.

  The determination in step 100 may be performed by, for example, determining an input signal based on an instruction to press a switch for instructing start of image display (not shown).

  In step 102, the preliminary drive voltage is applied.

  In the next step 104, after applying a display drive voltage for applying a display drive voltage corresponding to the image information of the image displayed on the image display medium 12 to the row electrode 34 and the column electrode 28, this routine is finished.

  Next, FIG. 9 shows an example of the movement of particles when a display driving voltage is applied after applying a preliminary driving voltage as shown in FIG. In FIG. 9, as a preliminary drive voltage, a voltage is applied to the column electrode 28 so that an electric field that causes the charged particle group 25 to move between adjacent electrodes of the column electrode 28 of the display substrate 16 is generated. A case where an alternating voltage is applied to the column electrode 28 and the row electrode 34 will be described so that an electric field capable of moving the charged particle group 25 between the display substrate 16 and the back substrate 18 is generated.

  FIG. 9 is a schematic diagram showing the movement of the charged particle group 25 when the initialization drive voltage is applied in the AA cross section of the image display medium 12 shown in FIG.

In the present embodiment, first, as shown in FIG. 9A, the row electrodes 34 and the white electrodes 22 are moved so that the white particles 22 move to the display substrate 16 side to display white on the entire surface for image erasure. When a voltage is applied to the column electrode 28, the white particles 22 move to the column electrode 28 side, and the black particles 24 move to the row electrode 34 side.
Next, as shown in FIG. 9 (B), as a preliminary drive voltage, a threshold value at which the charged particle group 25 can move between the column electrode 28b and the column electrode 28b adjacent to the column electrode 28c of the display substrate 16. A voltage V _LP1 greater than the voltage is applied. Here, the voltage V _LP1 is a voltage for moving the white particles 22 near the adjacent electrodes from the column electrode 28c side toward the column electrodes (28b and 28d) adjacent thereto. Then, as shown in FIG. 9C, the white particles 22 near the adjacent electrodes are caused to be on the column electrode 28c side by the edge electric field | V _LP1 | / d ₃ formed between the adjacent electrodes indicated by the arrows in the drawing. To the adjacent column electrode 28b and column electrode 28d side.
Here, immediately after applying a voltage so as to move between adjacent electrodes, if an alternating voltage is further applied between the column electrode 28 and the row electrode 34, particles that have started to move due to a strong electric field between the adjacent electrodes are further separated between the substrates. Can be moved to collide with the opposing substrate, and this impact force can start movement of particles that are difficult to move on the opposing substrate. By reciprocating with the alternating voltage, this effect is further expanded, and as shown in FIG. 9D, all the charged particle groups 25 move between the substrates.
As described above, by applying the initialization driving voltage before the display driving voltage is applied, the charged particle group 25 is easily moved in the direction in which the charged particle group 25 is easily moved between the substrates, and then the display driving is performed. A voltage can be applied, and the charged particle group 25 in which the responsiveness between the substrates with respect to the applied voltage is lowered can be easily moved between the substrates.

  As described above, according to the image display device 10 of the present invention, before the display drive voltage is applied, the preliminary drive voltage is provided on the display substrate 16 and the arrangement direction of the row electrodes 34 provided on the back substrate 18. A voltage is applied to one or both of the row electrode 34 and the column electrode 28 so that an electric field capable of moving the charged particle group 25 is generated in one or both of the arranged directions of the column electrodes 28.

  For this reason, before the display drive voltage is applied, a sufficient electric field for moving the charged particle group 25 in the arrangement direction of each electrode is provided between the plurality of electrodes of the column electrode 28 and between the plurality of electrodes of the row electrode 34. The charged particle group 25 whose responsiveness has decreased due to adhesion to the substrate, adhesion between the charged particle groups 25, and deterioration in charging characteristics, etc., can be formed and moved in the arrangement direction of the row electrodes 34 and the column electrodes 28, respectively. Can be made. Furthermore, if a display driving voltage is applied after the application of the preliminary driving voltage, the charged particle group 25 moved in the electrode arrangement direction by the application of the preliminary driving voltage is caused by the electric field formed by the application of the display driving voltage. The display substrate 16 and the back substrate 18 can be moved.

Therefore, even when charged particles having reduced responsiveness between the substrates with respect to the applied voltage are included, they can be easily moved between the substrates.
Further, even if the image display medium 12 is in a state where a cell in which the internal charged particle group 25 cannot move at all even when a display drive voltage is applied, by applying a preliminary drive voltage, The charged particle group 25 can be easily moved.

  In the above-described embodiment, the image display medium 12 has been described as having a simple matrix driving method. However, the present invention can also be applied to a case of being driven by an active matrix driving method.

  In the case of the active matrix driving method, the image display medium 50 is provided with a uniform electrode 27 on the surface of the display substrate 17 facing the back substrate 19 as shown in FIG. A plurality of pixel electrodes 29 are provided on the surface facing the display substrate 17 corresponding to each pixel. For this reason, when the preliminary drive voltage is applied, the preliminary drive voltage is applied so that an electric field that allows the charged particle group 25 to move between adjacent electrodes of the plurality of pixel electrodes 29 is formed. Good.

It is a schematic diagram which shows the image display apparatus of this invention. It is a schematic diagram which shows the electrical constitution of the image display apparatus of this invention. It is a diagram which shows the relationship between the electric field strength formed between the electrode provided in the display substrate, and the electrode provided in the back substrate which opposes, and an image display density. It is a schematic diagram which shows the application method of a preliminary | backup drive voltage, (A) is a schematic diagram in the case of applying a preliminary | backup drive voltage for every electrode to each of a column electrode and a row electrode, (B) is a column electrode and It is a schematic diagram which shows the case where a preliminary drive voltage is applied to each of the row electrodes for every two electrodes. It is a schematic diagram which shows the application method of a preliminary drive voltage, (A) is a schematic diagram which shows the case where a preliminary drive voltage is applied only to a column electrode, without applying a preliminary drive voltage to a row electrode, (B ) Is a schematic diagram showing a case where the preliminary drive voltage is applied only to the row electrode without applying the preliminary drive voltage to the column electrode. (A) is a schematic diagram showing a case in which a preliminary driving voltage is applied to the column electrodes and a voltage is applied to all the row electrodes so that an electric field is formed between the column electrodes and the row electrodes. (B) applies a pre-driving voltage to the row electrodes and applies a voltage to all the column electrodes so that an electric field is formed between the column electrodes and the row electrodes. It is a schematic diagram which shows a case. It is a schematic diagram showing the relationship between the particle peeling force with respect to the substrate and the rolling friction force with respect to the substrate of the charged particles attached to the display substrate or the back substrate. It is a flowchart which shows the process performed by the voltage application part of the image display apparatus of this invention. It is a schematic diagram which shows the motion of a charged particle when a display drive voltage is applied after application of a preliminary drive voltage according to the present invention. 4A and 4B are schematic views showing an image display device of a simple matrix driving method, in which FIG. 5A is a front view of a display substrate of an image display medium, and FIG. 5B is a front view of a rear substrate of the image display medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image display apparatus 12, 50 Image display medium 14 Voltage application part 16, 17 Display board | substrates 18 and 19 Back board | substrate 20 Gap member 22 White particle 24 Black particle 25 Charged particle 28 Column electrode 34 Row electrode

Claims (8)

A display substrate having at least translucency;
A rear substrate disposed facing the display substrate with a gap;
The display substrate includes a plurality of electrodes arranged on the same plane parallel to the opposing surface of the display substrate and the back substrate, at least with a space smaller than the gap between the display substrate and the back substrate. A first electrode;
A plurality of electrodes provided on the back substrate and arranged on the same plane parallel to the opposing surface of the back substrate and the display substrate, with at least a gap smaller than the gap between the display substrate and the back substrate. A second electrode;
It is enclosed between the display substrate and the back substrate, and moves between the display substrate and the back substrate according to an electric field formed by a voltage applied to the first electrode and the second electrode. At least one type of charged particle group possible;
A gap member for holding a gap between the display substrate and the back substrate and partitioning the display substrate and the back substrate into a plurality of cells;
An image display medium having
Before applying a display driving voltage for displaying an image on the image display medium, the charged particle group is placed between one or both of the adjacent electrodes of the first electrode and the adjacent electrode of the second electrode. So that a potential difference between the adjacent electrodes is larger than a threshold voltage at which the charged particle group starts to move, a pre-driving voltage is applied to the first electrode and the second electrode. Voltage application means for applying to either or both of the electrodes;
An image display device comprising: The image display apparatus according to claim 1, wherein the voltage applying unit applies the preliminary driving voltage via one electrode or a plurality of electrodes in an arrangement direction of the first electrode or the second electrode.   The image display device according to claim 1, wherein the preliminary drive voltage is an alternating voltage. The voltage application means has an electric field that allows the charged particle group to move between one or both of the adjacent electrodes of the first electrode and the adjacent electrode of the second electrode when the preliminary driving voltage is applied. As described above, after applying a voltage to one or both of the first electrode and the second electrode, an electric field that allows the charged particle group to move between the display substrate and the back substrate is generated. The image display device according to claim 1, wherein a DC voltage is applied to the first electrode and the second electrode. The voltage application means has an electric field that allows the charged particle group to move between one or both of the adjacent electrodes of the first electrode and the adjacent electrode of the second electrode when the preliminary driving voltage is applied. As described above, after applying a voltage to one or both of the first electrode and the second electrode, an electric field that allows the charged particle group to move between the display substrate and the back substrate is generated. As described above, the image display device according to claim 1, wherein an alternating voltage is applied to the first electrode and the second electrode.   The image display device according to claim 1, wherein the charged particle group is two or more types of charged particle groups having different charging characteristics.   In the image display medium, each of the first electrode and the second electrode is composed of an electrode group including a plurality of line-shaped electrodes, and is orthogonal to the first electrode and the second electrode. The image display device according to any one of claims 1 to 6, wherein the image display medium is a simple matrix-shaped image display medium arranged in such a manner.   7. The image display medium according to claim 1, wherein the image display medium is an active matrix image display medium including an electrode group including a plurality of electrodes in which at least the second electrode is provided for each pixel. The image display device according to item.

Images