JP4899379B2 - Image display medium driving apparatus and driving method - Google Patents

Description

  The present invention relates to an image display medium driving apparatus and driving method, and more particularly to an image display medium driving apparatus and driving method for performing rewrite display by moving colored particles by an electric field.

  2. Description of the Related Art Conventionally, an image display medium using colored particles is known as an image display medium that has a memory property and can be rewritten repeatedly. For example, as shown in FIG. 7, such an image display medium is enclosed between a pair of substrates and the substrates so as to be movable between the substrates by an applied electric field, and a plurality of types of particles having different colors and charging characteristics. And a group. In addition, a gap member for partitioning the substrates with a plurality of cells is provided between the substrates for the purpose of preventing the particles from being biased to a partial region in the substrates.

As a method for driving such an image display medium, for example, a technique described in Patent Document 1 has been proposed. In the technique described in Patent Document 1, when switching an image by driving an image display medium by passive matrix (simple matrix) driving, the particles to be moved are attracted to at least one of the substrates. After applying a voltage, it has been proposed to apply a voltage pulse so as to move the particles to be moved to a substrate opposite to the substrate to which the particles are attached.
JP 2002-82361 A

  However, as described above, the image display medium described in Patent Document 1 has a structure in which the substrates are partitioned by a plurality of cells by the gap member, as shown in FIGS. 7A and 7B. Thus, when there are a plurality of electrodes in a cell (FIG. 7 shows a case in which there are 2 rows × 4 columns of electrodes in a cell), for example, a black solid image different from a white background image is displayed. When black is displayed on the first line, more than normal black particles move. When black is displayed on the second line, sufficient black particles cannot be contributed to the display, and the white particles remain on the display surface side, resulting in a deterioration in black density. There is a problem that a sufficient density cannot be displayed.

  The present invention has been made to solve the above problem, and an object thereof is to uniformly display the display density in the cells partitioned by the gap member.

In order to achieve the above object, a drive device for an image display medium according to claim 1 includes a display substrate having at least translucency, a rear substrate facing the display substrate with a gap, and along a predetermined direction. A voltage corresponding to an image is applied between a plurality of first electrodes juxtaposed in parallel and a second electrode arranged opposite to the first electrode in a direction orthogonal to the first electrode, whereby the display substrate and A group of particles including at least two or more kinds of particles having different charged colors and colors enclosed between the substrates so as to move in accordance with an electric field formed between the substrate and the back substrate; A gap member for partitioning a cell including a plurality of first electrodes and a plurality of the second electrodes, and applying a voltage to the first electrodes and the second electrodes by simple matrix driving in order for each row, and to display the image by the movement of the And applying means for applying a voltage to the first electrode and the second electrode in accordance with an image to be displayed on the images display medium, when displaying an image of the same concentration in said cell, and displays the image at the beginning A physical quantity related to a voltage representing at least one of a magnitude of a voltage, a pulse width, the number of times of pulse application , and a pulse shape to be applied to the first electrode and the second electrode corresponding to the row is a row in which an image is displayed later as Naru rather smaller than the physical quantity to be applied to the first electrode and the second electrode corresponding to, is characterized by and a control means for controlling said applying means.

  According to the first aspect of the present invention, the image display medium moves the group of particles enclosed between the display substrate and the back substrate by applying an electric field between the first electrode and the second electrode. The image is displayed.

  In the applying means, a voltage is applied to the first electrode and the second electrode in accordance with the image to be displayed on the image display medium. As a result, an electric field is applied between the substrates, and the portion where the first electrode and the second electrode intersect with each other can display an image as a pixel.

  However, since the cells are partitioned by the gap member and there are a plurality of electrodes in the cell, as described above, the image display medium is driven by the passive matrix drive to move the particles to the first row. When a voltage is applied, more than normal particles move, and sufficient particles cannot contribute to the display when the second row is displayed.

Therefore, in the technique according to claim 1, when displaying the image with the same density in the cell by the control means , the voltage applied to the first electrode and the second electrode corresponding to the row in which the image is displayed first. the size of the pulse width, giving the number of pulses, and a physical quantity related to a voltage representative of at least one of the pulse shape, rather smaller than the physical quantity to be applied to the first electrode and the second electrode corresponding to the row to display an image after The application means is controlled so that

  As a result, it is possible to prevent the particles from moving more than usual in the row where the image is displayed first, and the image density in the same cell can be displayed uniformly.

According to a second aspect of the present invention, there is provided an image display medium driving method comprising: a display substrate having at least translucency; a rear substrate facing the display substrate with a gap; and a plurality of first substrates arranged in parallel along a predetermined direction. A voltage corresponding to an image is applied between one electrode and a second electrode arranged to face each other in a direction orthogonal to the first electrode, thereby causing a gap between the display substrate and the rear substrate. A group of particles including at least two or more kinds of particles having different charging polarity and color enclosed between the substrates so as to move according to the electric field formed between the first electrode and the second A gap member for partitioning the cell including a plurality of electrodes, and applying a voltage to the first electrode and the second electrode by simple matrix driving in order for each row and displaying an image by moving the particle group display all in that images display media An application step of applying a voltage to the first electrode and the second electrode according to an image, and the first electrode corresponding to a row in which an image is first displayed when displaying an image of the same density in the cell And a physical quantity relating to a voltage representing at least one of a magnitude of a voltage, a pulse width, the number of times of pulse application , and a pulse shape applied to the second electrode, the first electrode corresponding to a row displaying an image later, and wherein as Naru rather smaller than the physical quantity to be applied to the second electrode, is characterized by and a control step of controlling the applying step.

According to the second aspect of the present invention, in the image display medium, the particle group enclosed between the display substrate and the back substrate is moved by applying an electric field between the first electrode and the second electrode. The image is displayed.

  In the applying step, a voltage is applied to the first electrode and the second electrode in accordance with the image to be displayed on the image display medium. As a result, an electric field is applied between the substrates, and the portion where the first electrode and the second electrode intersect with each other can display an image as a pixel.

  However, since the cells are partitioned by the gap member and there are a plurality of electrodes in the cell, as described above, the image display medium is driven by the passive matrix drive to move the particles to the first row. When a voltage is applied, more than normal particles move, and sufficient particles cannot contribute to the display when the second row is displayed.

Therefore, in the technique according to claim 2 , when displaying an image of the same density in the cell in the control step, a voltage applied to the first electrode and the second electrode corresponding to the row in which the image is displayed first. the size of the pulse width, giving the number of pulses, and a physical quantity related to a voltage representative of at least one of the pulse shape, rather smaller than the physical quantity to be applied to the first electrode and the second electrode corresponding to the row to display an image after The application step is controlled so that

  By driving the image display medium in this way, it is possible to prevent the particles from moving more than usual in the row where the image is displayed first, and to uniformly display the image density in the same cell. it can.

  As described above, according to the present invention, there is an effect that the display density in the cells partitioned by the gap member can be displayed uniformly.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a partial cross-sectional view of an image display medium 10 according to an embodiment of the present invention. As shown in FIG. 1, the image display medium 10 is orthogonal to the scanning electrode 14 and a display substrate 18 in which a plurality of line-shaped transparent scanning electrodes 14 and a transparent insulating layer 16 are formed on a transparent substrate 12. A back-side substrate 28 having a line-shaped data electrode 20, a colored layer 22 and a transparent insulating layer 24 disposed on the substrate 26, and a positively charged black sealed between the substrates. It is composed of particles 30 and negatively charged white particles 32, and gap members 36 that partition the substrates into a plurality of cells 34 as shown in FIG.

  The image display medium 10 shown in FIG. 1 is a cross-sectional view taken along the line AA in FIG. In FIG. 2, the gap member 36 is shown in black for the sake of clarity. However, any color may be used as long as the image formed by the particles does not feel unnatural to the observer. Actually, it is composed of a transparent member.

  As shown in FIG. 2, the plurality of line-shaped scanning electrodes 14 are juxtaposed in the vertical direction (scanning direction S) in FIG. 2, and the plurality of line-shaped data electrodes 20 juxtaposed in the left-right direction in FIG. Are arranged so as to be orthogonal to each other. The intersection position of each scanning electrode 14 and each data electrode 20 constitutes a pixel. Each electrode is composed of, for example, an ITO (Indium Tin Oxide) electrode.

  In the present embodiment, the gap member 36 includes two scanning electrodes 14 and a plurality of data electrodes 20, and a plurality of rectangular cells 34 whose longitudinal direction is a direction orthogonal to the scanning direction S are formed. It has a grid shape. In FIG. 2, as an example, each cell 34 has a configuration in which two scanning electrodes 14 and four data electrodes 20 are arranged, that is, a configuration of 2 × 4 pixels per cell. However, the configuration is not limited to this. Absent.

  In FIG. 2, an electrode arrangement of a simple matrix structure of 8 rows × 8 columns is used for simplification of description, but in practice, the number of electrodes corresponding to the number of pixels necessary for image display is formed on each substrate. It goes without saying that it is done. That is, if m rows × n columns of pixels are required, m scanning electrodes 14 are formed on the substrate 12, and n data electrodes 20 are formed on the substrate 26.

  In the present embodiment, the scanning electrode 14 is provided on the display substrate side and the data electrode 20 is provided on the rear substrate side. Conversely, the data electrode 20 is provided on the display substrate side. The scanning electrode 14 may be formed on the side.

  Further, the scanning electrode 14 and the data electrode 20 may be formed not on the surface on the side where the display substrate 18 and the back substrate 28 face each other but on the surface on the opposite side, respectively. It may be arranged separately and independently on the outside. When the electrodes are provided separately from the image display medium, an electric field can be formed between the substrates by configuring the substrates with a dielectric member.

  In this embodiment, the black particles 30 are positively charged and the white particles 32 are negatively charged. However, the black particles 30 are negatively charged and the white particles 32 are positively charged. Good. As each particle, for example, insulating particles, conductive particles, and the like can be used.

Each member constituting the image display medium 10, it is possible to use those described in, for example, JP 2001-3122 2 5 JP.

  In such an image display medium 10, a predetermined voltage that is necessary for generating a potential difference that can move at least particles between the substrates and that can ensure a necessary concentration is applied to the scan electrode 14 and the data electrode 20. When applied between the electrodes, the black particles 30 and the white particles 32 at the positions move between the substrates. For example, when a predetermined voltage at which the potential of the scanning electrode 14 is positive with respect to the data electrode 20 is applied between the electrodes, the positively charged black particles 30 on the display substrate 18 side move to the back substrate 28 side. At the same time, the negatively charged white particles 32 on the back substrate 28 side move to the display substrate 18 side and are displayed in white.

  On the other hand, when a predetermined voltage at which the potential of the scanning electrode 14 is negative with respect to the data electrode 20 is applied between the electrodes, the negatively charged white particles 32 on the display substrate 18 side move to the back substrate 28 side. At the same time, the positively charged black particles 30 on the back substrate 28 side move to the display substrate 18 side and are displayed in black.

  Therefore, by applying a predetermined positive or negative voltage between the data electrode 20 and the scanning electrode 14 at a position corresponding to the pixel to which the particle is to be moved, the particle is moved according to the image and the image is displayed. Can do. Even after the voltage application is stopped, the black particles 30 or the white particles 32 remain attached to the display substrate 18 or the back substrate 28 by van der Waals force, mirror image force, or the like, and the image display is maintained.

  FIG. 3 shows a schematic configuration of the driving device 40 for displaying an image on the image display medium 10 based on the image data.

  The drive device 40 includes a scan electrode drive circuit 42, a data electrode drive circuit 44, power supply circuits 46 and 48, and a control device 50.

  The scan electrode drive circuit 42 is connected to each scan electrode 14 and applies various voltages supplied from the power supply circuit 46 to each scan electrode 14 in accordance with instructions from the control device 50.

  The data electrode drive circuit 44 is connected to each data electrode 20 and applies various voltages supplied from the power supply circuit 48 to each data electrode 20 in accordance with instructions from the control device 50.

  Image data corresponding to an image to be displayed on the image display medium 10 is input to the control device 50. Based on the input image data, the control device 50 scans a row number designation signal for designating the row number of the scan electrode 14 to be scanned and a scan electrode voltage designation signal for designating the type of applied voltage. A column number designation for designating the column number of the data electrode 20 to which a predetermined voltage is to be applied based on the line image corresponding to the scanning electrode 14 designated by the row number designation signal while being output to the electrode drive circuit 42 A data electrode voltage designation signal for designating the signal and the type of the predetermined voltage is output to the data electrode driving circuit 44, and the image display medium 10 is driven by passive matrix driving.

  The scan electrode drive circuit 42 applies a voltage of the type designated by the scan electrode voltage designation signal to the scan electrode 14 of the row designated by the row electrode designation signal from the control device 50, and the row number designation signal. An OFF voltage is applied to the scan electrodes 14 other than the scan electrode 14 designated by the above.

  The data electrode drive circuit 44 applies a voltage of the type specified by the data electrode voltage specification signal to the data electrode 20 of the column specified by the control device 50 by the column number specification signal, and also supplies a column number specification signal. An OFF voltage is applied to the data electrodes 20 other than the data electrode 20 designated by the above.

  Incidentally, as described above, the image display medium 10 according to the present embodiment includes two scanning electrodes and four data electrodes in one cell and is driven by passive matrix driving. In the case of displaying a solid image, the particles move toward the scan electrode 14 applied first, and the scan electrode 14 applied next cannot contribute sufficient particles to display.

  Thus, when an image having the same density is displayed over a plurality of rows in the same cell as described above, an experiment for improving the density difference in the same cell was conducted, and the result will be described.

  In this experiment, as the basic characteristics of the particles to be used (white particles 32 and black particles 30), those having an average diameter of 13 μm and a threshold voltage of ± 95 V (when the distance between the substrates is 0.2 mm) were used.

  Further, as a test piece, a strip-shaped electrode having a width of 0.5 mm and a pitch of 0.508 mm is formed on ITO with glass, and the scanning electrode 14 is on the upper side (surface side), and display can be performed by passive matrix driving. The electrodes were arranged so as to face each other.

  Then, a gap (inter-substrate distance) of 0.2 mm was held as a gap member 36 by a rib, particles were enclosed, and the upper limit substrate was bonded.

  First, initialization is performed by applying ± 250 V to the entire surface and driving the image display medium 10 (test piece) to display white.

  Next, the first line was displayed in black with the following writing parameters with a voltage application time shorter than that of the second line.

  The writing parameters for the second row were 2 pulses with a pulse width of 5 ms (5 ms between pulses), and the applied voltage was 190 V (85 + 85 V).

  The writing parameters for the first row were 2 pulses (5 ms between pulses) with a pulse width of 3, 4, 5 ms, and an applied voltage of 190 V (85 + 85 V).

  Then, as shown in FIG. 4, the display density was averaged in the longitudinal direction of the electrode, an 8-bit gradation profile was measured in the width direction of the electrode, and the black density was evaluated from the profile.

  FIG. 5A is a graph showing the result of evaluating the black density of the second row by changing the writing parameter of the first row when displaying the same density image over a plurality of rows in the same cell. .

  As shown in FIG. 5A, it can be seen that the density in the second row increases as the pulse width in the first row is decreased. Note that “□” in FIG. 5A indicates the black density when the first line is white.

  FIG. 5B is a graph showing the result of plotting the density difference between the first and second rows by the pulse width.

  As shown in FIG. 5B, the density difference was 0.4 or more before the improvement, that is, when the first and second lines were written with the same writing parameter (pulse width 5 ms), It can be seen that the density difference decreases as the pulse width of the row is shortened. Although the density shifts to the reverse (minus side) at a pulse width of 3 ms, there is no problem because the density difference itself is small.

  Thus, the density difference between the first row and the second row could be reduced by making the driving pulse width of the first row smaller than that of the second row.

  That is, in this embodiment, when displaying the same density image in the same cell, the control means applies the voltage of the scan electrode 14 and the data electrode 20 first applied in the same cell later. The scan electrode drive circuit 42 and the data electrode drive circuit 44 are controlled so that the voltage is lower than the voltage applied to the data electrode 20. Control by the control device 50 in this way makes the display density uniform in one cell.

  Next, processing performed by the control device 50 will be described in detail. FIG. 6 is a flowchart showing an example of the flow of processing performed by the control device 50 of the image display medium 10 according to the embodiment of the present invention.

  When the image data is input to the control device 50, in step 100, it is determined whether or not the image display has the same density over a plurality of lines in the same cell. That is, based on the preset cell arrangement and the image data input to the control device 50, whether or not a plurality of rows (rows corresponding to the plurality of scanning electrodes 14) have the same density display in the same cell. If the determination is affirmative, the process proceeds to step 102. If the determination is negative, the process proceeds to step 104.

  In step 102, the voltage applied to the scan electrode 14 and the data electrode 20 corresponding to the first writing row in the same cell is lowered by a predetermined amount from the voltage applied to the scanning electrode 14 and the data electrode 20 corresponding to the row to be written later. The setting is made in the scan electrode drive circuit 42 and the data electrode drive circuit 44, and the process proceeds to Step 104.

  In step 104, a voltage is applied to each electrode according to the image data. That is, based on the input image data, the scan electrode drive circuit outputs a row number designation signal for designating the row number of the scan electrode 14 to be scanned and a voltage designation signal for scan electrode for designating the type of applied voltage. And a column number designation signal for designating the column number of the data electrode 20 to which a predetermined voltage is to be applied based on the line image corresponding to the scanning electrode 14 designated by the row number designation signal. A data electrode voltage designation signal for designating a predetermined voltage type is output to the data electrode drive circuit 44. As a result, a voltage is applied to each electrode by the scan electrode driving circuit 42 and the data electrode driving circuit 44, and an image is displayed on the image display medium 10. At this time, when displaying images of the same density over a plurality of rows in the same cell, the applied voltages to the scan electrode 14 and the data electrode 20 corresponding to the first row to be written in the cell are set later in step 102. Since the setting is made to be lower by a predetermined amount than the voltage applied to the scanning electrode 14 and the data electrode 20 corresponding to the row to be written, when images of the same density are displayed over a plurality of rows in the same cell, Can be made uniform.

  In the above embodiment, by adjusting the pulse width, the voltage of the scan electrode 14 to be applied first in the same cell is set to be smaller than the voltage to be applied to the scan electrode 14 later. However, the present invention is not limited to this. For example, the magnitude of the voltage to be applied, the number of pulses applied, the pulse shape, and the like may be adjusted. In addition, at least one of the magnitude of the voltage, the pulse width, the number of times of pulse application, and the pulse shape may be adjusted.

  In the above embodiment, one cell is configured in 2 rows × 4 columns so that the voltage applied to the first row is a predetermined amount smaller than the voltage applied to the second row. When one cell is composed of three or more rows, the voltage to be applied may be reduced step by step as the first voltage application row is reached. That is, the voltage may be increased step by step from the electrode corresponding to the first row to the subsequent row.

1 is a partial cross-sectional view of an image display medium according to an embodiment of the present invention. It is a figure which shows arrangement | positioning of an electrode, and a gap | interval member. It is a block diagram which shows the structure of the drive device of the image display medium concerning embodiment of this invention. It is a figure for demonstrating the experiment for improving the density difference in the same cell, when displaying the image of the same density over several lines within the same cell. (A) is a graph showing the result of evaluating the black density of the second row by changing the writing parameter of the first row when displaying the image of the same density over a plurality of rows in the same cell. ) Is a graph showing the result of plotting the density difference between the first and second lines by the pulse width. It is a flowchart which shows an example of the flow of the process performed with the control apparatus of the image display medium concerning embodiment of this invention. It is a figure for demonstrating the problem of a prior art, (A) is a top view of an image display medium, (B) is XX sectional drawing of (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image display medium 14 Scan electrode 18 Display substrate 20 Data electrode 28 Back substrate 30 Black particle 32 White particle 36 Gap member 40 Drive apparatus 42 Scan electrode drive circuit 44 Data electrode drive circuit 50 Control apparatus

Claims (2)

A display substrate having at least translucency, a rear substrate facing the display substrate with a gap, a plurality of first electrodes juxtaposed along a predetermined direction, and a direction orthogonal to the first electrode When a voltage corresponding to an image is applied between the second electrodes arranged opposite to each other, the substrate moves so as to move according to an electric field formed between the display substrate and the rear substrate. A particle group including at least two or more kinds of particles having different colors and charged polarities enclosed therebetween, and a gap member that partitions the substrate into cells including a plurality of the first electrode and the second electrode, by applying a voltage to the first electrode and the second electrode in a simple matrix driving in sequence every row, in response to said image to be displayed on the images display medium that displays an image by the movement of the particles First electrode and second electrode And applying means for applying a voltage,
When displaying an image of the same density in the cell, the magnitude of the voltage applied to the first electrode and the second electrode corresponding to the row in which the image is displayed first , the pulse width, the number of pulses applied , and physical quantity relating to a voltage representative of at least one of the pulse shape, as later Naru rather smaller than the physical quantity to be applied to the first electrode and the second electrode corresponding to the row to display an image, and controls the applying means Control means;
An image display medium drive device comprising: A display substrate having at least translucency, a rear substrate facing the display substrate with a gap, a plurality of first electrodes juxtaposed along a predetermined direction, and a direction orthogonal to the first electrode When a voltage corresponding to an image is applied between the second electrodes arranged opposite to each other, the substrate moves so as to move according to an electric field formed between the display substrate and the rear substrate. A particle group including at least two or more kinds of particles having different colors and charged polarities enclosed therebetween, and a gap member that partitions the substrate into cells including a plurality of the first electrode and the second electrode, by applying a voltage to the first electrode and the second electrode in a simple matrix driving in sequence every row, in response to said image to be displayed on the images display medium that displays an image by the movement of the particles First electrode and second electrode And applying step of applying a voltage,
When displaying an image of the same density in the cell, the magnitude of the voltage applied to the first electrode and the second electrode corresponding to the row in which the image is displayed first , the pulse width, the number of pulses applied , and physical quantity relating to a voltage representative of at least one of the pulse shape, as later Naru rather smaller than the physical quantity to be applied to the first electrode and the second electrode corresponding to the row to display an image, and controls the applying step Control steps;
A method for driving an image display medium comprising:

Images