JP2006301665A - Image display device and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device and an image forming method capable of obtaining a constant image without loading a power supply. <P>SOLUTION: A voltage applying process of repeating an operation to drive particles by one frame, row by row, by generating an electric field corresponding to column data in every row, row by row, based upon the same image data while a voltage application time for every row is set to 1 msec is controlled to be performed repeatedly. In this case, an image of one frame having a blurred outline is displayed on a display surface of a display substrate 20 in the beginning and then the image of the one frame gradually becomes sharp each time the voltage applying process is repeated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display apparatus and an image forming method, and in particular, an image display that displays colored images by sealing the colored particles that move by an electric field between a pair of substrates arranged opposite to each other and attaching the colored particles. The present invention relates to an apparatus and an image forming method.

  Conventionally, as a rewritable sheet-like display medium, Twisted Ball Display (two-color coated particle rotation display medium), electrophoretic display medium, magnetophoretic display medium, thermal rewritable display medium, and liquid crystal having memory properties Etc. have been proposed.

  Among these display media that can be repeatedly rewritten, a thermal rewritable display medium, a liquid crystal having a memory property, and the like have a feature that the image memory property is excellent.

  A display medium using electrophoresis and magnetophoresis disperses colored particles that can be moved by an electric field or a magnetic field in a white liquid, and forms an image with the color of the colored particles and the color of the white liquid. For example, the image portion attaches colored particles to the display surface to display the color of the colored particles, and the non-image portion removes the colored particles from the display surface to display white due to the white liquid. In a display medium using electrophoresis and magnetophoresis, the movement of the colored particles does not occur without the action of an electric field or a magnetic field, and thus has a display memory property.

  In addition, the Twist Ball Display has a spherical surface in which half of the surface is white and the other side is black, and is reverse driven by the action of an electric field. The display is performed by applying an electric field so that is on the display surface side.

  According to this, since the particles do not cause inversion driving unless there is an action of an electric field, the display has a memory property. In the display medium, oil exists only in the cavities around the particles, but since it is almost in a solid state, it is relatively easy to make the display medium into a sheet.

  However, the thermal rewritable display medium and the liquid crystal having a memory property cannot display the display surface sufficiently white like paper, and the contrast between the image portion and the non-image portion is small when an image is displayed. Therefore, it is difficult to perform a clear display.

  In addition, in a display medium using electrophoresis and magnetophoresis, white display by white liquid is excellent, but when displaying the color of the colored particles, the white liquid enters the gap between the colored particles, so the display density decreases. Resulting in. Therefore, the contrast between the image portion and the non-image portion is reduced, and it is difficult to obtain a clear display.

  Furthermore, since the white liquid is sealed in these display media, when the display medium is removed from the image display device and handled roughly like paper, the white liquid may leak from the display medium.

  In the Twistig Ball Display, even if the white-coated hemisphere is perfectly aligned on the display side, the light rays that enter the gap between the spheres are not reflected and are lost internally, so in principle 100% White display is not possible. In addition, the white display is gray because of the influence of light absorption and light scattering in the cavity. Further, it is difficult to completely invert the particles, which also causes a decrease in contrast, and as a result, it is difficult to obtain a clear display. Furthermore, since the particle size is required to be smaller than the pixel size, fine particles with different colors must be manufactured for high-resolution display, which requires advanced manufacturing techniques. There is also a problem.

  Therefore, several display media using toner (particles) have been proposed as novel display media for solving the above-described problems (see Non-Patent Document 1).

  These display media have a configuration in which two types of particle groups (toners) having different colors and charging characteristics are sealed between a transparent display substrate and a back substrate facing this with a minute gap. By applying an electric field between the substrates in accordance with image information, particles of an arbitrary color are attached to the display substrate to perform image display.

According to the particle display medium using this particle group, since the particle group does not move unless an electric field acts, it has a display memory property, and since the image display medium is entirely composed of a solid, There is no problem. Since the display of white and black can be switched 100% in principle, it is possible to display a clear image with high contrast. Furthermore, by using particles with high concealability, it is possible to display a two-color image (for example, a black and white image) with a high display contrast. Hereinafter, the display medium using the particle group is simply referred to as an image display medium.
Japan Hardcopy, '99 Proceedings, p249-p252, Japan Hardcopy, '99 Fall Proceedings, p10-p13

  In the image display device using the image display medium described above, the image quality is determined by the movement state of the particles, and moving the particles stably and instantaneously is a major factor for improving the image quality. .

  In order to move particles stably and instantaneously, it is necessary to control three factors: the charge amount of the particles, the adhesion between the particles and the substrate, and the electric field applied to the space. However, among these three factors, the charge amount of the particle is determined by the material constituting the particle, and the adhesion force between the particle and the substrate is determined by the electrical properties of the material constituting the particle and the material constituting the substrate. Therefore, it is difficult to adjust the charge amount of the particles and the adhesion between the particles and the substrate in the image display medium once manufactured. Therefore, there is a problem that adjustment for moving particles stably and instantaneously is difficult.

  In addition, in an image display device using an image display medium, a high-contrast image of reflective display can be obtained. However, the difference in particle movement does not occur due to application of voltage during image formation, that is, particle movement. There is a problem that an unstable image display greatly depends on the state. In an image display device using liquid crystal, since an electric field is constantly applied, correction can be easily performed. However, in an image display device using an image display medium that displays an image by adhesion of particles, the image display device is stable within the electric field application time. There is a restriction that it must be configured to be able to output images. In addition, since the image is displayed by moving the particles, there is also a problem that the image display speed is slower than other image display devices such as an image display device using liquid crystal.

  In view of the above, an object of the present invention is to provide an image display device that can obtain a stable image without imposing a burden on a power source. Another object of the present invention is to provide an image forming method capable of forming a stable image without imposing a burden on the power source.

  In order to achieve the above object, an image display device according to an embodiment of the present invention includes a pair of substrates that are arranged to face each other and at least one of the substrates forms an image display region, and each of the pair of substrates. A plurality of electrodes disposed in the image display region so as to face each other, and sealed between the pair of substrates, and the pair of substrates according to a predetermined potential difference generated between the facing electrodes A plurality of electrodes when a voltage is applied based on the colored particle group moving to any one of the image data and one frame of image information displayed in the image display area to generate a predetermined potential difference between the plurality of electrodes. Display control means for repeatedly applying a voltage based on the same image information of one frame a plurality of times.

  According to a second aspect of the present invention, the plurality of electrodes provided on each of a pair of substrates that are arranged to face each other and at least one of the substrates forms an image display area, according to image information. A predetermined potential difference is generated between the electrodes facing each other to form an electric field between the electrodes facing each other, and particles enclosed between the pair of substrates according to the electric field are transferred to either side of the pair of substrates. And forming an image with the color of the particles that can be seen through the substrate on one side, in accordance with the image information based on one frame of image information displayed in the image display area When the electric field is formed between the opposing electrodes by generating a predetermined potential difference between the opposing electrodes at the same position, an image of the same frame between the opposing electrodes at the position corresponding to the image information Information-based voltage And performing repeatedly applied a plurality of times.

  By applying a voltage, the particles move and an image is displayed, but it takes a predetermined time for the particles to move completely to the substrate. This time depends on the strength of the electric field formed between the substrates. However, the strength of the electric field depends on the potential difference. Therefore, in the present invention, when the display control unit applies a voltage based on one frame of image information displayed in the image display area to generate a predetermined potential difference in the plurality of electrodes, Thus, voltage application based on the same image information of one frame is repeated a plurality of times.

  That is, in the present invention, even if the colored particles are not completely moved to the substrate side by a single voltage application, the display control means controls so that the voltage is repeatedly applied. To move to. At this time, in the image display area of the substrate, an image of one frame in which the outline with insufficient contrast is blurred initially appears, and the image is displayed so that the contrast gradually increases and the outline becomes clear. Become. Therefore, it is possible for the person who is looking at the image state where the outline is blurred to recognize the image to some extent, so that the image viewer can quickly recognize the image. This is highly effective when, for example, the image display device of the present invention is used for an advertising billboard or the like.

  Further, by repeatedly applying a voltage based on the same image information of one frame a plurality of times, the time required to display an image of one frame is shortened without applying a high voltage. Although this is not clear, when a voltage is applied, a strong electric field is generated in the region corresponding to the edge portion of the electrode compared to the region other than the edge, and it is better to repeatedly apply such a strong electric field many times. This is probably because the action of accelerating the movement of particles is greater than when a voltage is applied for a long time or a high voltage is applied. Therefore, according to the present invention, a stable image can be obtained with a short voltage application time.

  As described above, according to the present invention, there is an effect that a stable image can be obtained without imposing a burden on the power source.

  Hereinafter, an example of an embodiment to which an image display medium and an image display apparatus of the present invention are applied will be described in detail with reference to the drawings.

  As shown in FIG. 1, the image display apparatus according to the present embodiment includes an image display unit 10 and a voltage control unit 12 for forming an image on the image display unit 10.

  As shown in FIG. 2, in the image display unit 10, a display-side electrode 22, a spacer 26, and a back-side electrode 25 are sequentially formed between a transparent display substrate 20 that forms an image display surface and a back-side substrate 23. It is a configuration. A transparent surface coat layer 28 is formed on the surfaces of the display-side electrode 22 and the back-side electrode 25, respectively.

  The image display device corresponds to the image display device of the present invention, the image display unit 10 corresponds to the image display medium of the present invention, and the display substrate 20 and the back substrate 23 constituting the image display unit 10 are a pair of the present invention. The display-side electrode 22 and the back-side electrode 25 correspond to a plurality of electrodes of the present invention, and the voltage control unit 12 corresponds to display control means of the present invention.

  The display substrate 20 is composed of a transparent ITO-attached 7059 glass substrate, and the display-side electrode 22 formed on the display substrate 20 is composed of a plurality of line-like ITO electrodes arranged in parallel. As the display substrate 20, a transparent film or a flexible substrate FPC can be used instead of the glass substrate with the transparent electrode ITO.

  The back substrate 23 is composed of a printed wiring board. The printed wiring board is the most versatile member for electric field supply, and is suitable not only because it can be made into an arbitrary shape by etching the body foil, but also because it can be wired to the electrode by laminating epoxy resin .

  Of course, the present invention is not limited to a printed wiring board, but may be a substrate electric field such as a member that temporarily stores and holds charges, such as a dielectric or a photoconductor using a photoconductive material used in electrophotography. Any member having a function of generating the above can be applied.

  In addition, two types of particles, a first particle 40 and a second particle 42, are enclosed between the display substrate 20 and the back substrate 23. As the first particles 40, for example, titanium oxide-containing polymethyl having a volume average particle size of 20 μm obtained by stirring and mixing fine particles of titania treated with isobutyltrimethoxysilane with white particles at a weight ratio of 100 to 0.1. Methacrylate white spherical particles 40 can be used.

  Moreover, as the 2nd particle | grains 42, the fine powder obtained by processing a silica (A-130 by Nippon Aloesil Co., Ltd.) with an aminopropyltrimethoxysilane with black particle | grains is 100 to 0.2 weight ratio, for example. A black spherical powder of carbon-containing crosslinked polymethacrylate having a volume average particle size of 20 μm, which is stirred and mixed at a ratio (hereinafter referred to as black spherical particles 42) can be used. The first particles 40 and the second particles 42 correspond to the colored particles of the present invention.

  The display-side electrode 22 and the back-side electrode 25 have a configuration in which line-shaped electrodes are arranged in parallel, and have a simple matrix structure in which the extending directions are orthogonal to each other as shown in FIG.

  The display-side electrode 22 and the back-side electrode 25 are each connected to the voltage control unit 12, and the connection to the wiring of the voltage control unit 12 is, for example, an anisotropic conductive sheet in which conductive particles are embedded. Can be performed by thermocompression bonding. When the display substrate 20 has a large screen and individual pixels are large, the display substrate 20 can be directly attached to the substrate or coated with a conductive paste such as Doetite (trade name; manufactured by Fujikura Kasei Co., Ltd.). The display side electrode 22 and the wiring of the voltage control unit 12 can be electrically connected to achieve conduction.

  As shown in FIG. 1, the voltage control unit 12 includes an electric field generation device 30, a sequencer 32, and a controller (logic IC) 19. The electric field generation device 30 includes a power source 34, a waveform generation device 36, an amplification device ( And a relay (not shown) or a transistor circuit (not shown). Note that a relay (not shown) shorts all electrodes connected by an ON signal. The waveform generator 36 generates a waveform determined by a trigger-on signal input from the outside.

  In the image display device according to the present embodiment, the electric field generator 30 generates a potential on each electrode, and the sequencer 32 controls the potential of the electrode, so that the electrode formed on one of the display substrate 20 and the back substrate 23 In this case, an electric field corresponding to image information is simultaneously applied in the plane, and an electric field capable of driving particles in units of one row is applied to the electrode formed on the other side.

  Here, how to apply a voltage to the display-side electrode 22 and the back-side electrode 25 by the voltage control unit 12 will be described. FIG. 3 shows the relationship between the potential difference between the row electrode and the column electrode and the reflectance of the display surface. As shown in FIG. 3, when a high positive electric field is applied, the black spherical particles 42 move to the display substrate 20, and the reflectance of the display surface of the display substrate 20 decreases, resulting in black display. When a high negative electric field is applied, the white spherical particles 40 move to the display substrate 20, and the reflectance of the display surface of the display substrate 20 increases, resulting in white display. In addition, since the same effect | action will arise if it is a particle | grain with a different charge polarity, the display of arbitrary colors can be performed by combining the color of particle | grains other than white and black.

  As described above, the movement of particles occurs when a predetermined potential difference exists between the row electrode and the column electrode. The voltage control unit 12 applies a voltage to the display side electrode 22 and the back side electrode 25 so that a predetermined voltage difference occurs between the display side electrode 22 and the back side electrode 25.

  In addition, the image display unit of the present embodiment has a simple matrix structure. In order to form an image on the image display unit 10 having such a simple matrix structure, an electric field corresponding to column data for each row is set to 1. This operation is performed by performing the operation for generating one row and driving the particles row by row for one frame. In this case, a clear image is displayed line by line on the display surface of the display substrate 20.

  When an image is formed on the image display unit of this embodiment by such a method, it takes about 10 msec until a good image with sufficient contrast is formed, as shown in FIG.

  In this embodiment, the voltage application time per row is set to 1 msec, and an electric field corresponding to the column data for each row is generated for each row based on the same image data to drive the particles for each row. The voltage application process for performing one frame is controlled to be repeated a plurality of times. In this case, an image for one frame with a blurred initial contour is displayed on the display surface of the display substrate 20, and the image for one frame gradually becomes clear each time the voltage application process is repeated.

  Thus, by performing the voltage application process based on the same image data a plurality of times with the voltage application time being shortened, sufficient contrast can be obtained by repeating three times as shown in FIG. This is presumably because the movement of particles is promoted by repeated application of the same voltage.

  As described above, the present embodiment is configured to change the electric field applied to the space for particle movement by controlling the applied voltage by the voltage control unit 12 as a display control means for controlling the voltage. A stable image can be obtained with the application time.

  In the present embodiment, the case where the present invention is applied to the image display unit 10 having a simple matrix structure in which line-shaped electrodes are arranged to be orthogonal to each other has been described. For example, FIG. 6 (A) and FIG. As shown in B), the present invention can be applied to an image display unit 10 having an active matrix structure in which pixel electrodes are two-dimensionally arranged.

  In the above-described embodiment, the case where the image display unit 10 of the image display device includes the two substrates of the display substrate 20 and the back substrate 23 has been described. However, the present invention is a pair of substrates. The image display unit 10 may include a multi-layer structure such as a two-layer image display unit in which three substrates are arranged to face each other, a three-layer image display unit in which four substrates are arranged to face each other, or the like. The present invention can also be applied to an image display unit.

It is explanatory drawing which shows schematic structure of the image display apparatus which concerns on embodiment of this invention. It is sectional drawing which shows schematic structure of the image display part of the image display apparatus shown in FIG. It is explanatory drawing explaining the graph which shows the relationship between the electric potential difference between a row electrode and a column electrode, and the reflectance of a display surface, and the adhesion state of particle | grains. It is a graph which shows the relationship between the time (drive time) which applies a voltage, and the contrast of an image. It is a graph which shows the relationship between the frequency | count of repetition when the same voltage is repeatedly applied in a short time, and the contrast of an image. 6A is a schematic diagram illustrating the configuration of an image display unit having an active matrix structure, and FIG. 6B is a schematic explanatory diagram illustrating the configuration of the image display unit having an active matrix structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image display part 12 Voltage control part 20 Display substrate 22 Display side electrode 23 Back surface substrate 25 Back surface side electrode 26 Spacer 28 Surface coat layer 30 Electric field generator 32 Sequencer 34 Power supply 36 Waveform generator 40 1st particle | grain (white spherical particle)
42 2nd particle (black spherical particle)

Claims (2)

A pair of substrates that are arranged to face each other and at least one of the substrates forms an image display area;
A plurality of electrodes provided on each of the pair of substrates and arranged to face each other in the image display region;
A group of colored particles encapsulated between the pair of substrates and moving to one side of the pair of substrates according to a predetermined potential difference generated between the opposing electrodes;
When applying a voltage based on one frame of image information displayed in the image display area to generate a predetermined potential difference in the plurality of electrodes, the voltage based on the same one frame of image information for the plurality of electrodes Display control means for repeatedly applying a plurality of times,
An image display device comprising: Among a plurality of electrodes provided on each of a pair of substrates that are arranged to face each other and at least one substrate forms an image display region, a predetermined potential difference is provided between the electrodes facing each other according to image information. An electric field is formed between the opposing electrodes, and particles enclosed between the pair of substrates are moved to one side of the pair of substrates in accordance with the electric field, and the substrate on one side is moved. An image forming method for forming an image by the color of particles seen through
When forming the electric field between the opposing electrodes by generating a predetermined potential difference between the opposing electrodes at a position corresponding to the image information based on one frame of image information displayed in the image display area, An image forming method, wherein voltage application based on the same image information of one frame is repeated a plurality of times between opposing electrodes at positions corresponding to the image information.

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