JP4862309B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device, and more particularly to an image display device 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.

  2. Description of the Related Art Conventionally, as an image display medium (display device) that can be rewritten repeatedly, an image display medium having a configuration in which colored particles such as powder toner are enclosed between a pair of substrates (see, for example, Patent Document 1 and Patent Document 2). Proposed.

  These have a structure in which two types of charged particle groups having different colors and charging characteristics are sealed between a transparent display substrate and a back substrate facing the transparent display substrate. Charged to opposite polarity. By applying an electric field between the display substrate and the back substrate, the two types of charged particle groups move between the substrates, thereby changing the display density for display. In this image display medium, if a voltage is applied between the substrates according to the image information, a clear image display with high contrast can be performed.

  In such an image display medium, due to changes in environmental temperature, changes over time, and repeated rewriting, etc., the charged amount of charged particles encapsulated between the substrates decreases, and the substrate and charged particles adhere. Display drive voltage that forms an electric field to move particles to one of the substrates to display an image on an image display medium when a phenomenon such as facilitating or strong adhesion between charged particles occurs When is applied, the charged particle group is difficult to move between the substrates, and there is a problem in that the contrast and image quality are deteriorated due to a decrease in responsiveness corresponding to the applied voltage of the charged particle group.

  In Patent Document 3, a flying movement current generated by the movement of charged particles enclosed between a pair of substrates is detected, and an integral value of the flying movement current corresponding to the total charge amount of the flying particles is measured in advance. By determining how much particles have moved by comparing with the average charge amount of the deposited particles, and dividing the amount of these moved particles by the electrode area for applying a voltage between the substrates, By calculating the particle density per unit area, obtaining the display density when displayed by optical calculation based on this particle density, and performing feedback control that compares this integrated value with the grayscale indication voltage, the flying movement current Is disclosed that adjusts the deviation of the integrated value of γ from the gradation instruction voltage corresponding to the gradation level.

By applying this technique, it is considered that image quality deterioration can be suppressed.
JP 2001-033833 A JP 2001-31225 A JP 2004-054227 A

  However, in the above prior art, the current value due to the movement of the charged particles when a certain level of voltage is applied is detected. However, the charged amount of the charged particles depends on factors such as change over time, frictional charging, etc. It is conceivable that the charge amount is smaller than the charge amount when the display medium is sealed so as to have a predetermined charge amount, the same case, or the larger case. In the above prior art, it is possible to grasp that the charged state of particles has changed by measuring the value of the current that flows when a pulse voltage of a certain level is applied (measurement of the total amount of charge that flows). It is not possible to determine how the characteristics have changed. Therefore, when a change in the charge amount is detected, it is only possible to return to the original charge amount by performing initialization drive mainly to make the particle density uniform, and it is necessary to frequently perform initialization drive. . For this reason, there is a problem that the time required for display becomes longer, mechanical damage to particles increases, and energy consumption also increases.

  The present invention has been made in view of the above-described facts, and can accurately determine the deterioration of the display characteristics of the image display medium due to the change in the charge amount of the charged particles, and the display characteristics due to the change in the charge amount of the charged particles. An object of the present invention is to provide an image display device capable of easily adjusting the change without accompanying an extreme increase in initialization drive.

  According to a first aspect of the present invention, there is provided a display substrate having at least a light-transmitting property and having a first electrode, a back substrate having a second electrode facing the display substrate with a gap, and the display substrate. At least one that is enclosed between the back substrate and movable between the display substrate and the back substrate in accordance with an electric field formed by a voltage applied to the first electrode and the second electrode. An image display medium having a kind of charged particle group, a display driving voltage having a predetermined first voltage value for displaying an image on the image display medium, the charged particle group being movable, and A display characteristic detection voltage in which an absolute value of the voltage value increases from a second voltage value lower than the first voltage value to a third voltage value higher than the first voltage value by a predetermined value; Voltage applying means for applying to the second electrode, and the charged particles Measuring means for measuring the current value of the current generated by the movement of the display, and the current value measured by the measuring means between the start and end of application of the display characteristic detection voltage by the voltage applying means. And determining means for determining deterioration of display characteristics of the image display medium.

  According to another aspect of the present invention, there is provided an image display medium in which a charged particle group is enclosed between a display substrate having a first electrode and a back substrate having a second electrode.

  The voltage application means includes a display driving voltage having a predetermined first voltage value for displaying an image on the image display medium, and a second voltage value at which the charged particle group is movable and lower than the first voltage value. A display characteristic detection voltage in which the absolute value of the voltage value increases from a first voltage value to a third voltage value that is higher than the first voltage value by a predetermined value is applied to the first electrode and the second electrode. When the charged particles move between the display substrate and the back substrate according to the electric field formed by the voltage applied to the first electrode and the second electrode, a current is generated. The measuring means measures the current value of the current generated by the movement of the charged particle group. As the display characteristic detection voltage, the absolute value of the voltage value increases from a second voltage value that allows the charged particle group to move and a voltage value that is lower than the first voltage value to a third voltage value that is higher than the first voltage value by a predetermined value. When a voltage is applied to the first electrode and the second electrode, the charged particles do not move when the application of the display characteristic detection voltage is started, and the current value is not measured by the measuring means. When the value is increased, the charged particles start to move, and the current value corresponding to the movement is measured by the measuring means. For this reason, the movement state of the charged particles can be grasped from the current value measured by the measuring means. The discriminating unit discriminates the deterioration of the display characteristics of the image display medium based on the current value measured by the measuring unit between the start and the end of the application of the display characteristic detection voltage by the voltage applying unit. .

  The determination of the deterioration of the display characteristic is performed by the measurement unit between the start and end of application of the display characteristic detection voltage by the voltage application unit. When the voltage value of the display characteristic detection voltage corresponding to when the particle movement start current due to the movement of the charged particles is measured is substantially the same as the first voltage value, the display characteristic of the image display device main body is When it is determined as normal and is different from the first voltage value, it is possible to determine deterioration in display characteristics of the image display medium.

  Here, when the voltage value of the display characteristic detection voltage is substantially the same as the first voltage value, the voltage value of the display characteristic detection voltage is displayed on the image display device main body based on the first voltage value. This shows a case where the characteristics are within a range that does not change. This range can determine a specific range of the characteristics of the charged particle group used in the image display device depending on the configuration of the image display device.

  Note that, as shown in claim 3, the particle movement start current is a maximum current value measured by the measurement unit from the start to the end of application of the display characteristic detection voltage by the voltage application unit. It can be.

  In this way, the display particle characteristic that the charged particle group is movable and the absolute value of the voltage value increases from the second voltage value lower than the first voltage value to the third voltage value higher than the first voltage value by a predetermined value. When the detection voltage is applied to the first electrode and the second electrode, it is determined whether the image display medium is normal or not based on the current value measured by the measuring means. It is possible to determine the deterioration of the display characteristics of the image display medium.

  The image display device according to claim 4 is the image display device according to any one of claims 1 to 3, wherein the determination unit determines deterioration in display characteristics of the image display medium. The display driving voltage corresponding to the voltage value of the display characteristic detection voltage corresponding to the measurement of the particle movement start current is applied to the first electrode and the second electrode. Control means for controlling the voltage applying means can be included. In this way, by controlling the display drive voltage value according to the voltage value of the display characteristic detection voltage corresponding to when the particle movement start current of the charged particles when the display characteristic detection voltage is applied is measured, With such a configuration, it is possible to easily suppress deterioration of display characteristics of the image display medium.

  The image display device according to claim 5 is the image display device according to claim 4, wherein the particle movement start current is measured when the determination unit determines deterioration of display characteristics of the image display medium. According to the difference between the voltage value of the display characteristic detection voltage corresponding to and the first voltage value, the first voltage value of the display drive voltage, a predetermined first voltage application time, and The voltage application means can be controlled to apply a voltage obtained by adjusting at least one of the determined first voltage application times as the display drive voltage. As described above, the voltage applying unit applies the voltage obtained by adjusting at least one of the first voltage value of the display drive voltage, the first voltage application time, and the first voltage application frequency as the display drive voltage. By controlling the display, deterioration of display characteristics can be suppressed.

  The image display device according to claim 6 is the image display device according to claim 5, wherein the determination unit has a voltage value of the display characteristic detection voltage corresponding when the particle movement start current is measured. A larger voltage value corresponding to a difference between the voltage value of the display characteristic detection voltage and the first voltage value corresponding to the particle movement start current when the particle movement start current is measured when the first voltage value is larger than the first voltage value; The voltage application means is controlled so that a voltage adjusted to be at least one of an application time longer than the first voltage application time and an application frequency greater than the first voltage application frequency is applied as the display drive voltage. be able to.

Further, in the image display device according to claim 7, in the image display device according to claim 5 or 6, the determination means detects the display characteristic corresponding to the time when the particle movement start current is measured. When the voltage value of the voltage is smaller than the first voltage value, according to the difference between the voltage value of the display characteristic detection voltage corresponding to the measurement of the particle movement start current and the first voltage value. A voltage adjusted to be at least one of a small voltage value, an application time shorter than the first voltage application time, and an application frequency less than the first voltage application time is applied as the display drive voltage. The voltage application means can be controlled.

As described above, when the voltage value of the display characteristic detection voltage corresponding to when the particle movement start current is measured is larger than the first voltage value, the display characteristic corresponding to when the particle movement start current is measured. At least one of a large voltage value corresponding to the difference between the voltage value of the detection voltage and the first voltage value, an application time longer than the first voltage application time, and an application frequency greater than the first voltage application frequency. When the voltage value of the display characteristic detection voltage corresponding to when the particle movement start current is measured is smaller than the first voltage value, the particle movement start current is Based on the small voltage value corresponding to the difference between the voltage value of the display characteristic detection voltage corresponding to the measured value and the first voltage value, the application time shorter than the first voltage application time, and the first voltage application frequency Less application times Since the voltage was adjusted to one even without applying a said display driving voltage, it is possible to suppress the deterioration of display characteristics.

  The image display device according to claim 8 is the image display device according to any one of claims 1 to 7, wherein a plurality of the first electrodes are provided on the display substrate, A plurality of second electrodes are provided on the back substrate, and the measuring means measures a current value for each of the plurality of electrodes of the first electrode and the plurality of electrodes of the second electrode, and the determining means Is displayed for each region corresponding to the intersection of the plurality of electrodes of the first electrode and the plurality of electrodes of the second electrode based on each of the current values measured by the measuring means. If the deterioration of the characteristics is determined, the deterioration of the display characteristics of the image display medium can be determined in detail.

  The image display device according to claim 9 is the image display device according to any one of claims 1 to 8, wherein the image display medium is between the display substrate and the back substrate. A gap member may be further provided that maintains a gap and partitions the display substrate and the back substrate into a plurality of cells.

  Thus, when the image display medium is partitioned into a plurality of cells, as shown in claim 8, by selecting the first electrode and the second electrode corresponding to each cell, In addition, it is possible to determine the deterioration of the display characteristics.

  An image display device according to a tenth aspect is the image processing device according to any one of the first to ninth aspects, wherein the determination unit is configured to transmit a determination result to the outside of the main body of the image processing device. Communication means may be included.

  The image display device according to claim 11 is the image processing device according to any one of claims 1 to 10, wherein the voltage application unit displays the image before applying the display drive voltage. An initialization drive voltage for frictionally charging the charged particles of the medium is applied, and the determination unit applies the initialization drive voltage to the image display medium when determining the deterioration in display characteristics of the image display medium. Thus, since the voltage application means is controlled, it is possible to recover the decrease in the charge amount.

As described above, according to the image display device of the present invention, the charged particle group is movable and the second voltage value lower than the first voltage value of the display drive voltage is set to a predetermined value from the first voltage value. The first electrode and the second electrode measured by the measuring means between the start and end of application of the display characteristic detection voltage in which the absolute value of the voltage value increases to a high third voltage value. Since the deterioration of the display characteristics of the image display medium is determined based on the value of the current flowing between them, the change in the display characteristics of the image display medium due to the change in the charge amount of the charged particles can be accurately determined. It has the effect that it can be easily prepared without an increase in the drive.

  Hereinafter, embodiments of the present invention will be described in detail.

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

  As shown in FIG. 1, the image display device 10 includes an image display medium 12 for displaying an image, a voltage application unit 14 for applying a voltage to the image display medium 12, and a drive voltage applied to the voltage application unit 14. A control unit 42 for controlling and a current measurement unit 40 are included.

  The voltage application unit 14 applies a drive voltage to the image display medium 12 under the control of the control unit 42. As will be described in detail later, the control unit 42 includes a storage unit 44 for storing various data and a communication unit 45 for exchanging data and signals with an external device. The communication unit 45 is for exchanging various types of information with an external device by wire or wireless. The communication unit 45 receives image information of an image to be displayed on the image display medium 12 from the external device, and the image display medium 12 This is an interface for transmitting information indicating display characteristics to the outside.

  The image display medium 12 includes a transparent display substrate 16 provided on the viewing side X, a back substrate 18 facing the display substrate 16 with a gap, a gap member 20 for holding these substrates at a predetermined interval, and these It is composed of a group of charged particles 25 enclosed between the substrates.

  The display substrate 16 has a configuration in which a transparent support substrate (or glass substrate) 26, line electrodes 28, and an insulating layer 30 are laminated. A plurality of line-shaped electrodes 28 are formed on the support substrate 26.

  The line-shaped electrode 28 is provided for each pixel column adjacent to the display image displayed on the image display medium 12 in a predetermined direction. Note that a plurality of lines of electrode 28 may be provided corresponding to one pixel line.

  The back substrate 18 has a structure in which a support substrate 32, a line electrode 34, and an insulating layer 38 are laminated. A plurality of line-shaped electrodes 34 are formed on the support substrate 32.

  The line-shaped electrode 34 is provided for each adjacent pixel column in the direction orthogonal to the line-shaped electrode 28 formed on the display substrate 16 (a plurality of line-shaped electrodes 34 corresponding to one pixel column). A row may be provided.

  The gap member 20 holds the gap between the display substrate 16 and the back substrate 18 and prevents the charged particle group from moving in the lateral direction (horizontal with the support substrate surface).

  The charged particle group 25 includes colored charged particles having different charging characteristics. In the present embodiment, in order to simplify the description, the description will be made on the assumption that it is composed of white charged particles 22 and black charged particles 24 having different charging characteristics. The white charged particles 22 and the black charged particles 24 are particle groups having different charging characteristics. Specifically, the white charged particles 22 and the black charged particles 24 are selected so as to have opposite polarities (one is positive and the other is negatively charged). Yes. In this embodiment, in order to simplify the description, it is assumed that the black charged particles 24 are positively charged and the white charged particles 22 are negatively charged.

  A drive voltage is applied so that one electrode (for example, the line electrode 34) of the front substrate 16 and the rear substrate 18 of the image display medium 12 has a low potential and the other electrode (for example, the line electrode 28) has a high potential. Then, the positively charged black charged particles 24 in the charged particle group 25 move to the low potential electrode (that is, the line electrode 34) side by Coulomb force or the like, and the negatively charged white charged The particles 22 move toward the high potential electrode (that is, the line electrode 28). In this case, the color of the image display medium 12 when viewed from the viewing direction X side in FIG. 1 appears to be the color of the particles moving to the surface substrate 16 side, that is, white.

  If the potential difference between the line electrode 28 and the line electrode 34 is reversed, the color of the image display medium 12 can be reversibly changed. The color of the charged particle group 25 will be described later in detail, but can be selected arbitrarily. When two types of charged particles are used, one of which is white and the other is black, reversible display of white and black is possible. It is. The color of the particles can be arbitrarily selected by selecting the composition. In this method, each charged particle group 25 is once attached to the line-shaped electrode 28 and the line-shaped electrode 34, so that the display image is retained for a long period of time and the memory property is good.

  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 charged particles 22 and the black charged particles 24 (charged particle group 25) are the charged particle groups of the present invention. It corresponds to. The image display medium 12 corresponds to the image display medium of the present invention, and the line-shaped electrode (line-shaped electrode) 28 and the line-shaped electrode 34 respectively correspond to the first electrode and the second electrode of the present invention. The voltage application unit 14 corresponds to the voltage application means of the present invention. The control unit 42 corresponds to the determination unit and the control unit 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.

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

  The voltage application unit 14 includes a column electrode drive circuit 50, a row electrode drive circuit 48, and an external power supply 46. The line electrode 28 is connected to the column electrode drive circuit 50. The line electrode 34 is connected to the row electrode drive circuit 48. The row electrode drive circuit 48 and the column electrode drive circuit 50 are connected to the gate control unit 42 and the external power supply 46. The control unit 42 is connected to an image input device (not shown), and outputs a signal to the column electrode drive circuit 50 and the column electrode drive circuit 50 in accordance with image information input from the image input device.

  In such an image display device 10, an image writing signal (scanning signal) for each line electrode 34 is sent from the control unit 42 to the row electrode drive circuit 48, and displayed on the line electrode 34 from the row electrode drive circuit 48. A driving voltage is sequentially applied. At the same time, an image write signal corresponding to the line electrode 34 to which the display drive voltage is applied is sent from the control unit 42 to the column electrode drive circuit 50 in synchronization with the application of the display drive voltage sequentially applied to the line electrode 34. It is done. The column electrode drive circuit 50 applies a display drive voltage corresponding to the image information to the line electrodes 28 all at once. The scanning direction of the display driving voltage applied to the line electrode 34 is the arrow Z direction. Similarly, a desired image can be displayed on the image display medium 12 by sequentially applying a drive voltage in the scanning direction Z.

  Here, the drive voltage applied from the voltage application unit 14 to the image display medium 12 includes a display drive voltage, an initialization drive voltage applied to the image display medium 12 before application of the display drive voltage, and the image display medium 12. There is a display characteristic detection voltage for detecting the display characteristic.

  The display drive voltage is a voltage applied to the image display medium 12 when displaying an image on the image display medium 12. The initialization driving voltage is such that the charged particles 25 are sealed in the image display medium 12 so as to display white or black on the entire surface of the image display medium 12 in order to uniformly disperse the charged particle group 25 enclosed in the image display medium 12 in the image display medium 12. This voltage is used to selectively move the group 25 to either the display substrate 16 side or the back substrate 18 side according to the color being colored, or to frictionally charge the charged particle group 25. In the present embodiment, the initialization drive voltage will be described as a voltage for frictionally charging the charged particle group 25, although details will be described later. The display characteristic detection voltage is a voltage applied to the image display medium 12 to detect the display characteristics of the image display medium 12, and the charged particle group 25 moves from a low voltage value at which the charged particle group 25 cannot move. The voltage is such that the absolute value of the voltage value gradually increases up to a voltage value higher than the possible voltage value by a predetermined value.

  The control unit 42 sets the charge amount when the charge of the charged particle group 25 is in a stable state as the display drive voltage is initialized immediately after the charged particle group 25 is sealed in the image display medium 12. Accordingly, a predetermined voltage value (hereinafter referred to as a movement reference voltage value), a predetermined voltage that enables the charged particle group 25 to move between the substrates so that a predetermined display density can be achieved. The storage unit 44 is configured to store the application time and a predetermined number of times of voltage application in advance as reference values, and to store processing routines (FIGS. 4 and 8) described later in advance. The storage unit 44 stores in advance the voltage value and voltage application time of the initialization drive voltage as a reference value for the initialization drive voltage, and stores various data.

  It should be noted that initialization drive is performed immediately after the charged particle group 25 is sealed in the image display medium 12, and the charged particle group 25 is determined according to the charge amount when the charged particle group 25 is in a stable state. The moving reference voltage value that can be moved between the substrates so that the display density can be achieved corresponds to the first voltage value of the present invention, and the charged particle group 25 is predetermined according to the charge amount. The voltage application time that enables movement between the substrates so as to achieve the display density corresponds to the first voltage application time of the present invention, and the charged particle group 25 is given a predetermined amount according to the charge amount. The number of voltage applications that can be moved between the substrates so that the display density can be achieved corresponds to the first voltage application number of the present invention.

  When the display drive voltage is applied, the voltage application unit 14 applies the display drive voltage to the image display medium 12 so that a potential difference corresponding to the movement reference voltage value is generated between the display substrate 16 and the back substrate 18. In the present invention, in order to simplify the description, the potential difference between the line electrode 28 and the line electrode 34 of the image display medium 12 will be described as the voltage value of the display voltage value.

In the present embodiment, a 6 × 6 simple matrix configuration is used to simplify the description, and the six line-shaped electrodes 28 of the display substrate 16 are 28a, 28b, 28c, 28d, 28e, and 28f, respectively. The line-shaped electrodes 34 of the back 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 line-shaped electrode and the line-shaped electrode 34 of the back substrate 18 is formed to form a line-shaped electrode. Alternatively, the display substrate 16 may be provided with line-shaped electrodes, and the back substrate 18 may be provided with line-shaped electrodes.

  (Charged particles)

  The charged particle group 25 that can be used in the present embodiment may be any particle that can move between substrates by Coulomb force. In particular, a particle that is excellent in chargeability and has a small specific gravity is preferably used. A method of charging the charged particle group 25 positively or negatively is not particularly limited, and a method of charging particles such as a corona discharge electrode injection method or a friction method is used.

  The charged particle group 25 only needs to satisfy charging performance. For example, the charged particle group 25 can be formed from a resin, a charge control agent, a colorant, an inorganic additive, or the like, or a colorant alone. Specifically, insulating metal oxide particles such as glass beads, alumina, titanium oxide, thermoplastic or thermosetting resin particles, those having a colorant fixed on the surface of these resin particles, thermoplastic or thermal Examples thereof include particles containing an insulating colorant in the curable 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. Also, porous sponge-like particles or hollow particles enclosing air can be used as the white charged 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. In order to obtain a high contrast, it is preferable that the particle diameters of the two types of charged particle groups 25 are substantially the same. In this way, a situation in which large particles are surrounded by small particles and the original color density of the large particles is reduced is avoided. If the volume average primary particle size of the charged particle group 25 is smaller than the above range, the charge density of the charged particle group 25 is too high, the image force on the electrode or the substrate is too strong, and the followability when the electric field is reversed is obtained. Deteriorate. On the other hand, when the charged particle group 25 is larger than this range, the following property is good, but the memory property is inferior.

  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 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 line-shaped electrode 34 and the line-shaped electrode 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 line electrode 34 and the line electrode 28 may be embedded in the support substrate 32 and the support substrate 26, respectively. In this case, the material of each of the support substrate 32 and the support substrate 26 also serves as a dielectric layer. Since charging characteristics and fluidity of the charged particle group 25 may be affected, it is necessary to select appropriately according to the composition of the charged particle group 25 and the like.

  Furthermore, each of the line-shaped electrode 28 and the line-shaped electrode 34 may be disposed outside the image display medium 12 separately from the display substrate 16 and the back substrate 18.

  When the line-shaped electrode 28 and the line-shaped electrode 34 are formed on the display substrate 16 and the back substrate 18, respectively, the occurrence of leakage between the electrodes that causes damage to the electrodes and fixation of the charged particle group 25 is prevented. Therefore, a dielectric film may be formed as the insulating layer 30 and the insulating layer 38 on the electrodes (the line electrode 28 and the line electrode 34) as necessary. 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.

  The gap between the display substrate 16 and the back substrate 18 is not limited as long as the charged particle group 25 can move and the contrast by the movement of the charged particle group 25 can be maintained, but is usually 10 to 5000 μm, preferably 30 to 500 μm. Adjusted to The filling amount of particles is relative to the space volume between the substrates. It is preferable to fill so that the volume occupies 10 to 80%, preferably 10 to 70%.

  (Method for manufacturing image display medium)

  Although an example of the manufacturing method of the image display medium 12 is demonstrated below, it is not limited to the following methods. Moreover, in the following manufacturing method, as the charged particle group 25, Sekisui Plastics Industry Co., Ltd. is used for the black charged particles 24, and Sekisui Plastics Industry Co., Ltd. is used for the white charged particles 22. Although the case where manufactured techpolymer MBX-white is used is demonstrated, it is not restricted to such a composition.

  In this embodiment, a transparent conductive ITO glass substrate having a size of 70 mm × 50 mm × 1.1 mm is used as the display substrate 16 of the image display medium 12. A plurality of 02 mm line-shaped line electrodes 28 were formed. Similarly, the back substrate 18 is an ITO glass substrate of 70 mm × 50 mm × 1.1 mm, and a plurality of line-shaped line electrodes 34 having a width of 0.234 mm and an interval of 0.02 mm are formed on the support substrate 32 by etching. Created. Then, on each of the opposing surfaces of the display substrate 16 and the back substrate 18, a transparent polycarbonate resin was applied to a thickness of about 5 μm, thereby forming the insulating layer 30 and the insulating layer 38.

  As for the gap between the display substrate 16 and the back substrate 18, a thermosetting epoxy resin is applied to the back substrate 18 by screen printing in a desired pattern shape, this is heated and cured, and this process is repeated until the required height is reached. Formed by. The display area on which the image of the image display medium 12 is displayed was 20 mm × 20 mm, and the height (thickness of the image display medium 12) was 100 μm.

  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 is a black charged particle 24 of carbon-containing crosslinked polymethylmethacrylate having a volume average 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 Co., Ltd.). Titanium fine powder containing titanium oxide having a volume average particle size of 10 μm, which is obtained by mixing fine powder of titania treated with isopropyltrimethoxysilane in a ratio of 100 to 0.1 by weight. White charged particles 22 of methyl methacrylate (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 charged particles 24 were positively charged and the white charged particles 22 were negatively charged due to mutual friction.

  About 12 mg of mixed particles of such black charged particles 24 and white charged particles 22 were uniformly shaken off through the screen into the space between the gap member 20 and the gap member 20 on the back substrate 18. Then, the display substrate 16 is superimposed on the back substrate 18 via the gap member 20 so that the line-shaped line electrodes 34 of the back substrate 18 and the line-shaped line electrodes 28 of the display substrate 16 are orthogonal to each other. Both substrates were pressed and held with a double clip, and the gap member 20 and both substrates were brought into close contact to form the image display medium 12. Note that the total volume ratio of the white charged particles 22 and the black charged 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 line electrode 28 of the display substrate 16 as the column electrode drive circuit 50 and the line electrode 34 of the back substrate 18 as the column electrode drive circuit 50. The image display device 10 was manufactured by connecting each other so that signals could be exchanged.

  The mixing ratio of the white charged particles 22 and the black charged particles 24, the total volume ratio of the white charged particles 22 and the black charged particles 24 to the void volume between the substrates, and the volume average particle diameter of each particle are limited to the above values. It is not a thing.

(Change in current value due to movement of charged particle group 25 when display drive voltage is applied)

  In the image display device 10 including the image display medium 12 configured as described above, as described above, one of the display substrate 16 and the rear substrate 18 has a low potential and the opposite substrate side has a high potential. When a voltage is applied to the line electrode 34 and the line electrode 28, the charged particle group 25 moves due to Coulomb force or the like. Since the current flows when the charged particle group 25 moves in this manner, the drive voltage applied to the image display medium 12 is gradually increased from a low voltage at which the charged particle group 25 cannot move. When a value driving voltage is applied, it is possible to grasp whether the charged particle group 25 has moved between the substrates. The voltage value at which the charged particle group 25 moves will be described as a charged particle movement start voltage value.

That is, as shown in a diagram 66 in FIG. 3, when the drive voltage applied to the image display medium 12 is gradually increased, a current flows due to the movement of the charged particle group 25 from a state where the current value is constant, and the current flows. As the value increases and the movement of all the charged particle groups 25 ends, the current value decreases and returns to the value before the current value increase. The voltage corresponding to the maximum current value in the diagram 66 indicated by the current flowing from the start to the end of the application of the display characteristic detection voltage as a voltage for gradually increasing the absolute value of the drive voltage The value 62 will be described as the voltage at which the charged particle group 25 starts moving (charged particle movement start voltage).
The charged particle movement start voltage may be a voltage when current starts to flow when the application of the display characteristic detection voltage is started and the movement of the charged particle group 25 is started. In order to suppress the influence, the movement of the charged particle group 25 can be determined with higher accuracy by using the voltage value corresponding to the maximum current value.

  Here, the relationship between the drive voltage and the current value due to the movement of the charged particle group 25 when the display characteristic detection voltage is applied is the image display medium 12 having the same configuration, and the charged amount of the charged particle group 25 is the same. If it is constant, it is considered that the same relationship is always shown. However, the charge amount of the charged particle group 25 changes due to a change in the environmental temperature of the image display medium 12 or a change in the shape of the charged particle group 25 due to repeated rewriting. When appears, the charged particle movement start voltage value changes.

  In the present embodiment, the movement reference voltage value is obtained when initialization drive is performed immediately after the charged particle group 25 is sealed in the image display medium 12 and the charged particle group 25 is in a stable state. It is assumed that the voltage value of the display characteristic detection voltage corresponds to the maximum current value due to the movement of the charged particle group 25 when the display characteristic detection voltage is applied to the image display medium 12 with the charge amount held. .

  When the charged particle movement start voltage is higher than the movement reference voltage value (see voltage value 62 in FIG. 3 diagram 66) of the charged particle group 25 (see voltage value 68 in FIG. 3 diagram 63), the charged particles It can be said that the mobility of the group 25 with respect to the driving voltage is lowered with respect to the initial state.

  On the other hand, when the charged particle movement start voltage is lower than the movement reference voltage value (see voltage value 62) of the charged particle group 25 (see voltage value 69 in FIG. 3 diagram 67), the charged particle group 25 is Compared to the initial state, the mobility with respect to the drive voltage is improved. When a display drive voltage having the same voltage (moving reference voltage value) as that in the initial state is applied, background fogging occurs and display characteristics deteriorate. .

  Therefore, in the image display device 10 of the present invention, when a display characteristic detection voltage is applied to the image display medium 12, a current value that flows due to the movement of the charged particle group 25 is measured, and the image display medium 12 is measured based on the measurement result. The display drive voltage is adjusted while determining the deterioration of the display characteristics.

  Next, processing executed by the control unit 42 of the image display device 10 of the present invention will be described.

  When an image display instruction signal for displaying an image corresponding to the image information on the image display medium 12 is input, the control unit 42 executes the processing routine shown in FIG. 4 and proceeds to step 100. The image display instruction signal input is determined by determining whether or not the information input from the external device via the communication unit 45 is an image display instruction signal including image information of an image to be displayed on the image display medium 12. Alternatively, the image switch of the image displayed on the image display medium 12 may be stored in the storage unit 44 in advance, and an instruction switch operated by the user when instructing an image display not shown is a user. It may be determined by determining the input of the image display instruction signal that is input by being operated by.

  In step 100, it is determined whether a predetermined time has elapsed since the image was displayed on the previous image display medium. If the result is negative, the process proceeds to step 112. If the result is positive, the process proceeds to step 102.

  In step 102, the voltage application unit 14 is controlled so that a display characteristic detection voltage for detecting the display characteristic of the image display medium 12 is applied to the image display medium 12.

  The display characteristic detection voltage is a high voltage value at which the charged particle group 25 starts moving and is further moved from a low voltage value at which the charged particle group 25 enclosed in the image display medium 12 does not move. Thus, the applied voltage is such that the absolute value of the voltage value gradually increases.

  Further, as the display characteristic detection voltage, as shown in FIG. 5A, in addition to applying a voltage so that the voltage value is gradually increased from a low voltage value at which the charged particle group 25 does not move. It may be applied so as to increase stepwise, or may be increased discretely as shown in FIG. 5A and 5B, the voltage application interval is shorter than the response time of the charged particle group 25 to the applied voltage. There is a need.

  Further, as the display characteristic voltage, a voltage is set such that the voltage value is increased from a low voltage value at which the charged particle group 25 does not move to a voltage value that is a predetermined level higher than the voltage value at which the charged particle group 25 starts moving. What is necessary is just to apply, and a triangular wave as shown in FIG.5 (C), a sawtooth wave as shown in FIG.5 (D), and a sine wave as shown in FIG.5 (E) may be sufficient. In the triangular wave shown in FIG. 5C, the absolute value of the voltage gradually increases in the voltage range 66 and the voltage range 67, and in the sawtooth wave shown in FIG. 5D, in the voltage range 68 and the voltage range 69, The absolute value of the voltage gradually increases, and the absolute value of the voltage gradually increases in the voltage range 70 and the voltage range 71 in the sine wave shown in FIG. The relationship between the voltage value applied to the medium 12 and the current value due to the movement of the charged particle group 25 may be such a voltage that indicates such a triangular wave, sawtooth wave, or sine wave.

  When the voltage application unit 14 is controlled by the process of step 102, the voltage application unit 14 applies the display characteristic detection voltage to the line electrode 28 and the line electrode 34 of the image display medium 12.

  In the next step 104, the voltage value is changed from the voltage value at which the charged particle group 25 cannot move to the voltage value that is higher by a predetermined level than the voltage value at which the charged particle group 25 starts to move by the process of step 102. Measurement result of moving current due to movement of the charged particle group 25 by the current measuring unit 40 from the start of application of the display characteristic detection voltage to the end of application when the display characteristic detection voltage that increases is applied to the image display medium 12. Read.

  In the next step 106, the voltage value of the applied voltage of the display characteristic detection voltage corresponding to the maximum current value among the current values from the start of application of the display characteristic detection voltage to the end of application, Obtained as the charged particle movement start voltage value. Specifically, if the relationship between the voltage applied to the image display medium 12 and the current measured by the movement of the charged particle group 25 is the relationship shown in the diagram 64 of FIG. A voltage value 68 corresponding to the value is read as a charged particle movement start voltage value.

  Next, in step 108, it is determined whether or not the charged particle movement start voltage value read in step 106 is equal to the movement reference voltage value stored in the storage unit 44.

  In the present embodiment, in the process of step 108, whether or not the charged particle movement start voltage value read in step 106 is equal to the movement reference voltage value as the first voltage value stored in the storage unit 44. In the determination of step 108, it may be determined whether or not the charged particle movement start voltage value is a value within a predetermined range with respect to the movement reference voltage value. In this case, the predetermined range needs to be within a range of −10% to + 10% of the movement reference voltage value, and preferably within a range of −3% to + 3% of the movement reference voltage value.

  When the charged particle movement start voltage value is greater than + 10% of the movement reference voltage value or less than −10%, the display characteristics of the image display medium 12 are such that the charged particle group 25 is enclosed in the image display medium 12. Immediately after that, the initialization drive is performed and the charged particle group 25 is in a stable state.

  If the charged particle movement start voltage value read in step 108 is affirmative in step 108 and equal to the movement reference voltage value, the process proceeds to step 110, and after clearing a counter (detailed later) in the storage unit 44, Proceed to step 111.

  In step 111, the moving reference voltage value, the voltage application time, and the voltage application frequency as the reference values stored in the storage unit 44 are displayed as the voltage value, the voltage application time, and the voltage application frequency of the display drive voltage. The drive voltage is stored in a predetermined memory area (hereinafter referred to as a display drive voltage storage area).

  In the next step 112, the display drive voltage stored in the display drive voltage storage area in the storage unit 44 is read.

  In the next step 114, image information to be displayed on the image display medium 12 is read from the storage unit 44.

  In the next step 116, the display drive voltage read in step 112 is applied to the image display medium 12 based on the image information, and then this routine is terminated.

  On the other hand, if the charged particle movement start voltage value read in the above step 106 is negative and the result read in the above step 106 is different from the movement reference voltage value stored in the storage unit 44 in advance, the process proceeds to step 117 and the image display medium. Grasping 12 display characteristics deterioration.

  In the next step 118, it is determined whether or not the counter value n of the counter provided in the control unit 42 is “0”, and if affirmative and the counter value n is “0”, Proceeding to step 120, the initialization drive voltage is applied to the image display medium 12. When the initialization drive voltage is applied to the line electrode 34 and the line electrode 28 by the process of step 120 and the charged particle group 25 is frictionally driven, the charged particle group 25 is charged. The charge amount of the charged particle group 25 can be recovered by the process of step 120.

  In the next step 122, after counting up the counter value n of the counter stored in advance in the storage unit 44, the process returns to step 102.

  If the result in Step 118 is negative and the counter value n is not “0” and the initialization drive is performed, but the charged particle movement start voltage value is different from the movement reference voltage value, the process proceeds to Step 124.

  In step 124, it is determined whether or not the charged particle movement start voltage value read in step 106 is larger than the movement reference voltage value. If the result is affirmative and larger than the movement reference voltage value, the process proceeds to step 126.

  If the result of step 124 is affirmative and the charged particle movement start voltage value is larger than the movement reference voltage value, the charged amount of the charged particle group 25 is charged to the image display medium 12 by charging the charged particle group 25. Since the initializing drive is performed immediately after the charging of the charged particle group 25 and the charged amount of the charged particle group 25 is in a stable state, it is lower than the charge amount, so that the display drive voltage is determined as a reference value. If the display drive voltage prepared so as to be at least one of the reference voltage value, the voltage application time, and the voltage application number is larger than the voltage value, the long voltage application time, and the large number of voltage application times, the charged particle group 25 is not applied. The predetermined display density is not moved in achievable manner. For this reason, in the next step 126, at least one of the movement reference voltage value, the voltage application time, and the voltage application frequency determined as the reference value is set as a difference between the charged particle movement start voltage value and the movement reference voltage value. Change the size accordingly.

  In the process of step 126, at least one of the movement reference voltage value, the pulse width, and the pulse number of the display drive voltage that is determined in advance as a reference value is set to the charged particle movement start voltage value and the movement reference voltage value. You may make it change so that it may become large according to a difference.

  In the next step 128, the voltage value changed in step 126, the voltage application time, and the voltage application count are stored as display drive voltages in the display drive voltage storage area of the storage unit 44, and then the process proceeds to step 112.

  On the other hand, when the result in Step 124 is negative and the charged particle movement start voltage value is smaller than the movement reference voltage value, the charged amount of the charged particle group 25 is charged to the image display medium 12 by charging the charged particle group 25. Since the initialization drive is performed immediately after the particle group 25 is sealed and the charge of the charged particle group 25 is in a stable state, it is higher than the charge amount, so that the display drive voltage is a reference value. If a display drive voltage prepared so as to have a voltage value smaller than a predetermined moving reference voltage value, a short voltage application time, and a small number of times of voltage application is not applied, background fogging occurs due to the movement of the charged particle group 25. Therefore, in the next step 130, at least one of the movement reference voltage value, the voltage application time, and the voltage application frequency determined as the reference value is set as a difference between the charged particle movement start voltage value and the movement reference voltage value. Change to be smaller accordingly.

  In the process of step 130, at least one of the movement reference voltage value, the pulse width, and the pulse number of the display drive voltage that is determined in advance as a reference value is set to the charged particle movement start voltage value and the movement reference voltage value. You may make it change so that it may become small according to a difference.

  In the next step 132, the movement reference voltage value, the voltage application time, and the voltage application frequency changed in step 130 are stored as display drive voltages in the display drive voltage storage area of the storage unit 44, and then the step 112. Proceed to

  As described above, according to the image display apparatus 10 of the present invention, as a display characteristic detection voltage for detecting the display characteristic of the image display medium 12, the charged particle group 25 is charged from a low voltage value at which the charged particle group 25 cannot move. A voltage at which the absolute value of the voltage value gradually increases to a high voltage value higher than the voltage value by which the particle group 25 can move is applied to the line electrode 28 and the line electrode 34 of the image display medium 12, and this display is performed. The charged particles obtained based on the measurement result obtained by measuring the current value of the current generated by the movement of the charged particle group 25 from the start to the end of the application of the characteristic detection voltage starts to move between the substrates. The voltage (charged particle movement start voltage value) is the charge amount when the initialization drive is performed immediately after the charged particle group 25 is sealed in the image display medium 12 and the charged particle group 25 is in a stable state. Almost identical By determining whether equal or not the movement reference voltage value of time, the display characteristics of the image display medium 12, it is determined whether or not reduced.

  Therefore, it is possible to accurately determine the deterioration of the display characteristics of the image display medium 12 with a simple configuration.

  In addition, when the charged particle movement start voltage value is different from the movement reference voltage value, or when the charged particle movement start voltage value is higher than the movement reference voltage value when the charged particle movement start voltage value is different from a predetermined range or more, the movement reference voltage determined as the reference value Since the display drive voltage is adjusted so that at least one of the value, the voltage application time, and the number of times of voltage application is increased according to the difference between the charged particle movement start voltage value and the movement reference voltage value, the charged particles Even when the charge amount of the group 25 is reduced, it is possible to suppress the deterioration of display characteristics.

  Similarly, when the charged particle movement start voltage value is lower than the movement reference voltage value, at least one of the movement reference voltage value, the voltage application time, and the number of times of voltage application determined as the reference value is set to start charged particle movement. Since the display drive voltage is adjusted so as to decrease according to the difference between the voltage value and the movement reference voltage value, even when the charge amount of the charged particle group 25 increases, the deterioration of display characteristics is suppressed. Can do.

  Therefore, it is possible to suppress deterioration of display characteristics due to a change in the charge amount of the charged particle group 25.

  Furthermore, since the initialization drive voltage is applied to the image display medium 12 when the charged particle movement start voltage value is different from the movement reference voltage value, the charge amount of the charged particle group 25 can be recovered.

  4 is performed between all the line electrodes 28 and 34 as the current generated by the movement of the charged particle group 25 when the display characteristic detection voltage is applied to the entire image display medium 12. Although the case where the generated current value is measured by the current measuring unit 40 has been described, the current value is measured for each of the plurality of line-shaped electrodes of each of the line-shaped electrodes 28 and the line-shaped electrodes 34, and the display drive voltage is measured for each line. May be adjusted.

In this case, as shown in FIG. 2, current measuring units 40 ₁ to 40 ₆ for measuring the current values of the plurality of line electrodes 28 _{1 to} 28 ₆ of the line electrode 28 may be provided. Good. Further, as shown in FIG. 6, current value measuring units 41 _{1 to} 41 ₆ for measuring current values of the line electrodes 34 _{1 to} 34 ₆ may be further provided.

In this way, as shown in FIG. 7, each of the line-shaped electrodes 28 and the line-shaped electrodes 34 is selectively applied to each of the plurality of electrodes, as shown in FIGS. 7A and 7B. While applying the display characteristic detection voltage, current measuring units 40 ₁ to 40 ₆ and current value measuring unit 41 are provided for each of the line electrodes (line electrodes 34 _{1 to} 34 ₆ and line electrodes 28 _{1 to} 28 ₆ ), respectively. _{1 to} 41 ₆ , the current value is measured, the charged particle movement start voltage value is obtained for each of the line-shaped electrodes 34 _{1 to} 34 ₆ and the line-shaped electrodes 28 _{1 to} 28 ₆ , and compared with the movement reference voltage value, What is necessary is just to distinguish the line-shaped electrode corresponding to a display characteristic defect area | region. If it is determined as defective, the display drive voltage may be adjusted for each line electrode in the same manner as in FIG.

If you do this. It is possible to determine whether or not the display characteristics are defective for each of the line electrodes 34 _{1 to} 34 ₆ and the line electrodes 28 _{1 to} 28 _6, and it is possible to adjust the deterioration of the display characteristics with high accuracy.

  As described above, when the line-shaped electrode corresponding to the display characteristic defect area is determined, information that can identify the line-shaped electrode corresponding to the display characteristic defect area is transmitted to the external device via the communication unit 45. You may do it. In this way, information indicating a display characteristic defect can be presented to the outside of the image display device 10.

  Further, as shown in FIG. 7C, the image display medium 12 is divided into a plurality of areas so as to include a plurality of areas where the line-shaped electrode 28 and the line-shaped electrode 34 are opposed to each other, and a selection is made for each of the divided areas. The display characteristic detection voltage is applied, and the value of the current flowing through the line electrode 28 and the line electrode 34 corresponding to each region is measured from when the display characteristic detection voltage is applied until the display characteristic detection voltage is finished. By doing so, in the same manner as described above, it is possible to determine the deterioration of display characteristics for each section and to adjust the display drive voltage.

  As shown in FIG. 7D, a display characteristic detection voltage is selectively applied to each area where the line electrode 28 and the line electrode 34 face each other, and the current value measured for each area. Based on the above, it is possible to determine the deterioration of the display characteristics and adjust the display drive voltage in the same manner as described above. In this way, display characteristic deterioration of the image display medium 12 can be suppressed with high accuracy.

  In the case of FIGS. 7C and 7D as well, when the display characteristic defect area is determined, information that can identify the display characteristic defect area is transmitted to the external device via the communication unit 45. You may do it. In this way, information representing the display characteristic defect area can be presented to the outside of the image display device 10.

  In the present embodiment, as shown in FIG. 4, the case where the charged particle moving voltage start voltage value and the moving reference voltage value are compared has been described. However, the drive voltage that can be applied to the image display medium 12 in advance is described. Each of the upper limit value and the lower limit value of the voltage value may be determined in advance, and it may be further compared whether or not the upper limit value is less than or less than the upper limit value. In this case, when the charged particle movement voltage start voltage value is equal to or higher than the upper limit value or the charged particle movement start voltage value is equal to or lower than the lower limit value, the initialization drive voltage is controlled to be applied to the image display medium 12. Good.

  Specifically, as shown in FIG. 8, the charged particles corresponding to the maximum current value measured when the processing of step 100 to step 108 is executed and the display characteristic detection voltage is applied to the image display medium 12. When the movement start voltage value is the same as the movement reference voltage value, the processing from step 111 to step 116 is executed, and after the movement reference voltage is stored as the display drive voltage in the display drive voltage storage area, After the display drive voltage corresponding to the display drive voltage stored in the display drive voltage storage area is applied to the image display medium 12 based on the image information, this routine is finished.

  If the result in Step 108 is negative and the charged particle movement voltage start voltage value and the movement reference voltage value are not the same, the process proceeds to Step 117, and after the display characteristic deterioration is determined, the process proceeds to Step 124, and the charged particle movement It is determined whether or not the start voltage value is larger than the movement reference voltage value.

  If the determination in step 124 is affirmative, the process proceeds to step 202, where it is determined whether or not the charged particle movement start voltage value is equal to or greater than a predetermined upper limit value. If the determination is affirmative, the initialization drive voltage is set to the image display medium 12. If the result of step 102 is negative, the process proceeds to step 126, and at least one of the movement reference voltage value, the voltage application time, and the number of times of voltage application determined as the reference value is transferred to the charged particles. The change is made so as to increase in accordance with the difference between the start voltage value and the movement reference voltage value. In step 128, the change value is stored as the display drive voltage value in the display drive voltage storage area, and then the process proceeds to step 112.

  On the other hand, if the determination in step 124 is negative, the process proceeds to step 204, where it is determined whether or not the charged particle movement start voltage value is less than a predetermined lower limit value. Is applied to the image display medium 12, the process returns to step 102. If the determination is negative, the process proceeds to step 130, and at least one of a moving reference voltage value, a voltage application time, and a voltage application count determined as a reference value is obtained. Is changed so as to become smaller in accordance with the difference between the charged particle movement start voltage value and the movement reference voltage value, and in step 132, the changed value is stored in the display drive voltage storage area as the display drive voltage value, and then the above step 112 is performed. move on.

  In this way, the initial drive voltage is applied only when the charged particle movement start voltage value is not less than the upper limit value or less than the lower limit value, so that the initialization drive voltage can be efficiently applied to the image display medium 12.

  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.

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 voltage applied to an image display medium, and the electric current value which generate | occur | produced by the movement of the charged particle by the applied voltage. It is a flowchart which shows the process performed by the control part of the image display apparatus of this invention. It is a diagram which shows the increase rate per unit time of a display characteristic detection voltage, (A) is a diagram which shows the case where a voltage value is raised digitally, (B) is a voltage value discretely. (C) is a diagram showing a case where the voltage value is raised so as to be a triangular wave, and (D) is a diagram showing a voltage value so as to be a sawtooth wave. It is a diagram which shows the case where it raises, (E) is a diagram which shows the case where a voltage value is raised so that it may become a sine wave. It is a schematic diagram which shows the electrical constitution of the image display apparatus of this invention. It is a schematic diagram which shows an example which applies a display characteristic detection voltage for every line-shaped electrode, (A) is a schematic diagram which shows the case where a display characteristic detection voltage is applied to a specific line-shaped electrode, (B) (A) is a schematic diagram which shows the case where a display characteristic detection voltage is applied to a specific line-shaped electrode different from (A), and (C) is applied to the line-shaped electrode so as to apply the display characteristic detection voltage to a specific region. It is a schematic diagram showing a case where a display characteristic detection voltage is applied. (D) shows a display characteristic detection voltage selectively for each area where the line electrode on the display substrate side and the line electrode on the back substrate side face each other. It is a schematic diagram which shows the case where it applies. It is a flowchart which shows the process different from FIG. 4 performed by the control part of the image display apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image display apparatus 12 Image display medium 14 Voltage application part 16 Front surface board 18 Back surface board 25 Charged particle group 28 Line-shaped electrode 34 Line-shaped electrode 40 Current measurement part 42 Control part 44 Storage part 45 Communication part

Claims (11)

A display substrate having at least translucency and having a first electrode;
A rear substrate facing the display substrate with a gap and having 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 group of charged particles possible;
An image display medium having
The display driving voltage having a predetermined first voltage value for displaying an image on the image display medium, and the second voltage value that is lower than the first voltage value and that can move the charged particle group. Voltage application means for applying to the first electrode and the second electrode a display characteristic detection voltage in which an absolute value of the voltage value increases to a third voltage value higher than the first voltage value by a predetermined value;
Measuring means for measuring a current value of a current generated by movement of the charged particle group;
Discrimination for discriminating deterioration of display characteristics of the image display medium based on a current value measured by the measurement unit between the start and end of application of the display characteristic detection voltage by the voltage application unit Means,
An image display device.   The determination unit corresponds to a case where a particle movement start current due to the movement of the charged particles is measured by the measurement unit between the start and end of application of the display characteristic detection voltage by the voltage application unit. When the voltage value of the display characteristic detection voltage to be determined is substantially the same as the first voltage value, it is determined that the display characteristic of the image display device body is normal and is different from the first voltage value. The image display device according to claim 1, wherein deterioration of display characteristics of the image display medium is determined.   3. The image according to claim 2, wherein the particle movement start current is a maximum current value measured by the measurement unit between the start and end of application of the display characteristic detection voltage by the voltage application unit. Display device.   When the determination means determines the deterioration of the display characteristics of the image display medium, the display drive voltage corresponding to the voltage value of the display characteristics detection voltage corresponding to the measurement of the particle movement start current, 4. The image display device according to claim 1, further comprising a control unit that controls the voltage application unit so as to be applied to the first electrode and the second electrode. 5.   The discriminating means, when discriminating the deterioration of the display characteristics of the image display medium, includes a voltage value of the display characteristic detection voltage corresponding to the measurement of the particle movement start current and the first voltage value. A voltage obtained by adjusting at least one of the first voltage value of the display drive voltage, a predetermined first voltage application time, and a predetermined first voltage application number according to the difference is displayed. The image display apparatus according to claim 4, wherein the voltage application unit is controlled to be applied as a drive voltage.   When the particle movement start current is measured when the voltage value of the display characteristic detection voltage corresponding to when the particle movement start current is measured is greater than the first voltage value, the determination unit A large voltage value corresponding to a difference between the corresponding voltage value of the display characteristic detection voltage and the first voltage value, an application time longer than the first voltage application time, and an application more than the first voltage application frequency The image display device according to claim 5, wherein the voltage application unit is controlled to apply a voltage adjusted to be at least one of the number of times as the display drive voltage. When the particle movement start current is measured when the voltage value of the display characteristic detection voltage corresponding to when the particle movement start current is measured is smaller than the first voltage value, the determination unit A smaller voltage value corresponding to a difference between the corresponding voltage value of the display characteristic detection voltage and the first voltage value, an application time shorter than the first voltage application time, and less than the first voltage application frequency The image display apparatus according to claim 5 or 6, wherein the voltage application unit is controlled so that a voltage adjusted to be at least one of the number of times of application is applied as the display drive voltage.   A plurality of the first electrodes are provided on the display substrate, a plurality of the second electrodes are provided on the back substrate, and the measuring means includes the plurality of electrodes of the first electrode and the second electrode. A current value is measured for each of the plurality of electrodes, and the discriminating unit is configured to determine, based on each of the current values measured by the measuring unit, the plurality of electrodes of the first electrode and the second electrode The image display device according to claim 1, wherein deterioration of display characteristics is determined for each region corresponding to an intersection portion where a plurality of electrodes intersect.   2. The image display medium further includes a gap member that maintains a gap between the display substrate and the back substrate and partitions the display substrate and the back substrate into a plurality of cells. Item 9. The image display device according to any one of items 8.   The image display apparatus according to claim 1, wherein the determination unit includes a communication unit for transmitting a determination result to the outside of the image processing apparatus main body.   The voltage application means applies an initialization drive voltage for frictionally charging the charged particles of the image display medium before applying the display drive voltage, and the determination means reduces the display characteristics of the image display medium. 11. The image display device according to claim 1, wherein when the determination is made, the voltage application unit is controlled to apply the initialization drive voltage to the image display medium.

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