JP6420042B2 - Display medium drive device, drive program, and display device - Google Patents

Description

  The present invention relates to a display medium drive device, a drive program, and a display device.

  U.S. Patent No. 6,057,049 is a method for driving an electro-optic display having at least one pixel capable of achieving at least two different gray levels, wherein at least two different waveforms are the same between predetermined gray levels. The pre-determined gray level used for the transition depends on the duration of the pause time of the pixel in the state where the transition begins, and these two waveforms are: (a) inserting at least one balanced pulse pair; Different from each other by at least one of (b) deleting at least one balanced pulse pair, and (c) inserting at least one period of zero voltage, an “balanced pulse pair” means a total of the balanced pulse pairs Meaning a series of two pulses of opposite polarity so that the impulse is substantially zero It has been disclosed.

JP 2011-085944 A

  The present invention provides a display medium that can suppress variations in density between pixels when displaying an image on a display medium, as compared with a case where an initialization voltage is applied to adjacent pixels of the display medium at the same timing. An object of the present invention is to provide a driving device, a driving program, and a display device.

  In order to achieve the above object, the display medium driving device according to claim 1 moves between the pair of substrates according to an electric field formed between the pair of substrates, at least one of which has translucency. An application unit that applies a voltage according to an image to each of the plurality of pixels of the display medium in which the particle group is sealed, and when displaying a different display color in each of the adjacent pixels, Control means for controlling the application means so that the application timing of the initialization voltage applied to each of them differs.

  According to a second aspect of the present invention, the control means increases the deviation in application timing of the initialization voltage applied to each of the adjacent pixels as the density of the display color to be displayed increases. The application means is controlled.

  According to a third aspect of the present invention, the control means applies the initialization voltage to one of the adjacent pixels as the density of the display color to be displayed increases, and then applies the initial voltage to the other pixel. The application means is controlled so that the voltage value of the initialization voltage applied to the one pixel increases during the period until the activation voltage is applied.

  According to a fourth aspect of the present invention, the particle group is a plurality of types of particle groups having different movement start voltages that move between the pair of substrates, and the control unit is configured to display the display color according to the display color to be displayed. The application unit is controlled so that the application procedure of the initialization voltage applied to each of the adjacent pixels is different.

The invention of the display medium driving program according to claim 5 causes a computer to function as control means constituting the driving device according to any one of claims 1 to 4.

  The display device according to claim 6 includes a pair of substrates, at least one of which is light-transmitting, and a group of particles that move between the pair of substrates according to an electric field formed between the pair of substrates. And a display medium driving device according to any one of claims 1 to 3.

  According to a seventh aspect of the present invention, in the display device according to the seventh aspect, a movement start voltage that moves between the pair of substrates according to an electric field formed between the pair of substrates, at least one of which has a light-transmitting property, is provided. A display medium in which a plurality of different types of particle groups are enclosed, and the display medium driving device according to claim 4.

  According to the first, fifth, sixth, and seventh aspects of the invention, when displaying an image on the display medium, the pixel-to-pixel comparison is performed as compared with the case where the initialization voltage is applied to each of the adjacent pixels of the display medium at the same timing. It is possible to suppress the variation in the concentration of the.

  According to the second aspect of the present invention, the pixel is compared with the case where the application timing of the initialization voltage applied to each of the adjacent pixels of the display medium is fixed without considering the density of the image displayed on the display medium. There is an effect that the variation in the density can be further suppressed.

  According to the third aspect of the invention, the initialization voltage is applied to one of the adjacent pixels of the display medium without considering the density of the image displayed on the display medium, and then the initialization voltage is applied to the other image. Compared with the case where the voltage value of the initialization voltage applied to one image is fixed in the period until application, it is possible to further suppress the variation in density between pixels.

  According to the fourth aspect of the present invention, compared with the case where the application procedure of the initialization voltage applied to each of the adjacent images is fixed without considering the display color of the image displayed on the display medium, it is between pixels. There is an effect that variation in display color density can be suppressed.

It is the schematic of the display apparatus in 1st Embodiment. It is a block diagram which shows the principal part structure of the electric system of a display apparatus. It is a figure which shows the threshold value characteristic of the particle group in 1st Embodiment. It is a figure which shows the waveform of the reset voltage applied to the conventional pixel electrode. It is the schematic which shows the behavior of a particle group accompanying the application of the conventional reset voltage. It is a flowchart of the drive program of the display medium in 1st Embodiment. It is a figure which shows the waveform of the reset voltage applied to the pixel electrode in 1st Embodiment. It is the schematic which shows the behavior of a particle group accompanying the application of the reset voltage in 1st Embodiment. It is a figure which shows the evaluation result at the time of performing the drive program of the display medium in 1st Embodiment. It is the graph which showed the average OD change rate at the time of changing the number of shift frames for every white reset drive and black reset drive. It is a figure which shows the waveform of the reset voltage which changed the initial reset voltage. It is the graph which showed the average OD change rate at the time of changing an initial reset voltage. It is the graph which showed the average OD change rate when changing the number of shift frames and the initial reset voltage. It is the schematic of the display apparatus in 2nd Embodiment and 3rd Embodiment. It is a figure which shows the threshold value characteristic of the particle group in 2nd Embodiment. It is a flowchart of the drive program of the display medium in 2nd Embodiment. It is the schematic which shows the behavior of the particle group by the 1st reset process in 2nd Embodiment. It is a flowchart of the 2nd reset process in 2nd Embodiment. It is the schematic which shows the behavior of the particle group by the 2nd reset process in 2nd Embodiment. It is a figure which shows the threshold value characteristic of the particle group in 3rd Embodiment. It is a flowchart of the drive program of the display medium in 3rd Embodiment. It is a flowchart of the 3rd reset process in 3rd Embodiment. It is the schematic which shows the behavior of the particle group by the 1st reset process in 3rd Embodiment. It is the schematic which shows the behavior of the particle group by the 3rd reset process in 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Members having the same functions and functions may be given the same reference numerals throughout the drawings, and redundant descriptions may be omitted.

  In addition, when it is necessary to describe the characteristics and the like by distinguishing each color for cyan and the like, the color code C, red for the color code R, white for the color code W, and black for the color code K. A color code (C, R, W, K) corresponding to each color is added to the end of the code to be distinguished. Further, particles and particle groups are indicated by the same reference numerals.

<First Embodiment>

  FIG. 1 is a diagram schematically illustrating a display device 100 according to the first embodiment. The display device 100 includes a display medium 10 and a drive device 20 that drives the display medium 10. Then, the driving device 20 applies a voltage according to image information including a voltage application unit 30 that applies a voltage between the display-side electrode 3 and the pixel electrode 4 of the display medium 10 and color information of an image displayed on the display medium 10. And a control unit 40 that controls the application unit 30.

  The display medium 10 includes a display substrate 1, a back substrate 2, a display side electrode 3 provided on the display substrate 1, a pixel electrode 4 provided on the back substrate 2, and a dispersion medium 6 sealed between the display substrate 1 and the back substrate 2. The particle group 11 that migrates the dispersion medium 6 and the floating particle group 12 that floats in the dispersion medium 6 are included.

A translucent display substrate 1 serving as an image display surface and a back substrate 2 serving as an image non-display surface are disposed to face each other with a predetermined gap. When a voltage is applied to the display side electrode 3 and the pixel electrode 4 from the voltage application unit 30, an electric field corresponding to the applied voltage is generated in the gap formed by the display substrate 1 and the back substrate 2. Note that both the display substrate 1 and the back substrate 2 may be light-transmitting substrates.

  Here, the display-side electrode 3 is an electrode arranged over the entire surface of the display substrate 1 and one electrode (common electrode) having translucency. The pixel electrode 4 is a general term for individual electrodes arranged on the back substrate 2. In order to simplify the description below, the operation of the display medium 10 will be described using the two pixel electrodes 4 of the pixel electrode 4A and the pixel electrode 4B. However, three or more pixel electrodes 4 are arranged on the rear substrate 2. Needless to say. In FIG. 1, only the connection between the voltage application unit 30 and the pixel electrode 4 </ b> B is illustrated, but actually, the voltage application unit 30 and each of the pixel electrodes 4 are connected, and a voltage is applied to each pixel electrode 4. Applied. Note that both the display-side electrode 3 and the pixel electrode 4 may be translucent electrodes.

  In this embodiment, as an example, the pixel electrode 4 is composed of a TFT electrode, and n horizontal scanning lines (address lines Y1 to Yn) and m vertical signal lines (data lines X1 to Xm). ), A so-called active matrix driving method is used in which a matrix is formed and each pixel electrode 4 is arranged at the intersection.

  In this case, the scanning line is connected to the gate of the pixel electrode 4 and applies a voltage for determining on / off of the TFT electrode. The signal line is connected to the drain or source of the pixel electrode 4 and applies a voltage to the pixel electrode 4.

  That is, the pixel electrode 4 on the wiring is conducted through one of the scanning lines Yi (i = 1 to n), and a voltage is applied to the pixel electrode 4 from the signal line. By performing this scanning over all scanning lines Y1 to Yn (one frame), the image displayed on the display medium 10 is rewritten.

  Accordingly, the application time of the voltage applied to the pixel electrode 4 can be varied by controlling the number of frames to which the voltage is applied. The pixel electrode 4 is not limited to the TFT electrode, and the driving method of the pixel electrode 4 is not limited to the active matrix method.

  Here, each gap formed by disposing each pixel electrode 4 and the display side electrode 3 to face each other is referred to as a pixel. When a voltage is applied from the voltage application unit 30 to the pixel electrode 4 and the display-side electrode 3 for each pixel, an electric field is generated between the pair of substrates 1 and 2 corresponding to each pixel. A particle group 11 (to be described later) moves in the pixel according to the strength of the electric field, whereby a display color corresponding to the image information is displayed on each pixel, and an image is displayed on the display medium 10.

  As shown in FIG. 1, each pixel includes, for example, a dispersion medium 6 that is a permeable insulating liquid, a black particle group 11 </ b> K dispersed in the dispersion medium 6, and a floating particle group (not shown). White particle group 12W is arranged.

  The black particle group 11K is charged to, for example, the positive electrode, and a voltage exceeding a predetermined threshold value (movement start voltage) is applied to the display-side electrode 3 and the pixel electrode 4 so that the black particle group 11K becomes a pair of substrates. It has an electrical property of moving between 1 and 2 and adhering to either one of the pair of substrates 1 and 2.

  On the other hand, the white particle group 12W (not shown) is a particle group having a smaller charge amount than the black particle group 11K. Therefore, even when a voltage for moving the black particle group 11K to one of the pair of substrates 1 and 2 is applied between the pair of electrodes 3 and 4, the moving speed of the black particle group 11K is increased. Since the moving speed of the white particle group 12 </ b> W is slower than the white particle group 12 </ b> W, the white particle group 12 </ b> W floats in the dispersion medium 6 without adhering to any of the pair of substrates 1 and 2. Moreover, the particle amount of the white particle group 12W enclosed between the pair of substrates 1 and 2 is larger than the particle amount of the black particle group 11K. Therefore, for example, when the black particle group 11K adheres to the back substrate 2 side, the dispersion medium 6 so that the white particle group 12W covers the black particle group 11K before the black particle group 11K when viewed from the display substrate 1 side. Since it floats inside, white is observed from the display substrate 1 side.

  In the present embodiment, description is made on the assumption that the pixel is configured by the unit of the pixel electrode 4, but the configuration unit of the pixel is not limited to this. For example, the form which treats the several pixel electrode 4 collectively as one pixel may be sufficient. Further, the color of the particles is not limited to white and black, and is appropriately selected.

  The drive device 20 (the voltage application unit 30 and the control unit 40) applies a voltage corresponding to the display density of the black particles 11K instructed as the color information of the image to the display side electrode 3 and the pixel electrode 4 to display the image. An image is displayed on the display medium 10 by attaching black particles 11K having a particle amount corresponding to the display density to the substrate 1 side.

  The voltage application unit 30 is a voltage application device for applying a voltage to the display side electrode 3 and the pixel electrode 4, and is electrically connected to each of the display side electrode 3 and the pixel electrode 4. The voltage application unit 30 is connected to the control unit 40 and varies the application timing and voltage value of the voltage applied to the display side electrode 3 and the pixel electrode 4 in accordance with instructions from the control unit 40. In the present embodiment, as an example, the display-side electrode 3 is grounded, and the voltage applied to the pixel electrode 4 is variable.

  The control unit 40 is configured as a computer 40, for example, as shown in FIG. The computer 40 includes a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, a nonvolatile memory 404, and an input / output interface (I / O) 405 via the bus 406. The voltage application unit 30 is electrically connected to the I / O 405.

  In this case, for example, a drive program for the display medium 10 to be described later is written in the ROM 402 of the computer 40, and the CPU 401 reads and executes the drive program for the display medium 10 to control the voltage application unit 30.

  Here, the nonvolatile memory 404 may be connected to the outside of the computer 40 via the I / O 405, and may be an external storage device such as a memory card, for example.

  FIG. 3 shows characteristics of applied voltage (hereinafter referred to as threshold characteristics) necessary for moving the black particles 11K to the display substrate 1 side or the back substrate 2 side in the display device 100 according to the present embodiment. .

  The horizontal axis in FIG. 3 represents the voltage applied to the pixel electrode 4, and the vertical axis represents the display density of the black particles 11K observed from the display substrate 1 side.

  When a voltage exceeding the threshold value V1a is applied to the pixel electrode 4, the black particles 11K are peeled off from the back substrate 2 in an amount corresponding to the electric field formed between the substrates 1 and 2, and the display substrate 1 side. Move to. When a voltage equal to or higher than the threshold value V1 is applied to the pixel electrode 4, the black display density observed from the display substrate 1 side becomes 100%.

  Further, when a voltage less than the threshold value −V1a is applied to the pixel electrode 4, the black particles 11K are peeled off from the display substrate 1 in an amount corresponding to the electric field formed between the substrates 1 and 2, and the back surface Move to the substrate 2 side. When a voltage equal to or lower than the threshold value −V1 is applied to the pixel electrode 4, the black display density observed from the display substrate 1 side becomes 0%.

  Note that the threshold value refers to the attractive force between the black particles 11K that acts on the black particles 11K attached to either the display substrate 1 or the back substrate 2, for example, Van der Waals force or intermolecular force, and the like. The energy necessary for separating the black particles 11K from the display substrate 1 or the back substrate 2 by cutting off the attractive force between the black particles 11K and the substrates 1 and 2 due to the mirror image force, that is, the movement of the black particles 11K starts. It shows energy.

  The movement start energy of the black particles 11K depends on the magnitude of the voltage applied between the electrodes 3 and 4 and the voltage application time.

  Therefore, even if the voltage of the magnitude | size required in order to cut off the attractive force between the black particles 11K and the attractive force between the black particles 11K and the substrates 1 and 2 is applied between the electrodes 3 and 4, the black particles 11K When the application of voltage is stopped before reaching the energy required for peeling from the substrates 1 and 2, the black particles 11K are not peeled off from the substrates 1 and 2 and are attached to one of the substrates 1 and 2 side. Will remain.

  In the present embodiment, for convenience of explanation regarding the threshold value, the magnitude of the voltage necessary for peeling the black particles 11K from the display substrate 1 and the back substrate 2, that is, the movement start voltage will be described. It is not a value determined by the magnitude of the applied voltage applied between 4 and 4, but a value determined by the applied voltage applied between the electrodes 3 and 4 and the length of application time of the applied voltage.

  Next, the drive control of the black particle group 11K having the threshold characteristic shown in FIG. 3 will be specifically described with reference to FIGS.

  FIG. 4 is a diagram illustrating a waveform of a voltage applied to the pixel electrode 4 of each pixel when displaying black on the pixel A and white on the pixel B. FIG.

  Here, the pixel A means a pixel formed by the display side electrode 3 and the pixel electrode 4A in FIG. 1, and FIG. 4A shows a voltage applied to the pixel A, that is, a voltage applied to the pixel electrode 4A. The waveform is shown. The pixel B is a pixel formed by the display-side electrode 3 and the pixel electrode 4B in FIG. 1, and FIG. 4B shows a voltage applied to the pixel B, that is, a voltage applied to the pixel electrode 4B. The waveform is shown.

  FIG. 5A is a diagram showing the state of the black particle group 11K before the voltage shown in FIGS. 4A and 4B is applied to the pixel A and the pixel B, and the black particle It is assumed that the group 11K is attached to the display substrate 1 side in advance. That is, the display color of the pixel A and the pixel B is black.

  FIG. 5B is a diagram illustrating the state of the black particle group 11K when the voltage −V1b that is a voltage equal to or lower than the threshold −V1 is applied to the pixel A and the pixel B at time t1. In this case, as shown in FIG. 5B, since the black particle group 11K is positively charged, the black particle group 11K adheres to the back substrate 2 side in both the pixel A and the pixel B. In this state, when the pixel A and the pixel B are observed from the display substrate 1 side, the white particle group 12W floating in the dispersion medium 6 is observed before the black particle group 11K, and the display colors of the pixel A and the pixel B are It turns white.

  FIG. 5C shows a state of the black particle group 11K when the voltage applied to the image A and the pixel B is changed from the voltage −V1b to the voltage V1b that is equal to or higher than the threshold value V1 at time t2. It is. In this case, as shown in FIG. 5C, since the black particle group 11K adheres to the display substrate 1 side for both the pixel A and the pixel B, the display color of the pixel A and the pixel B is black.

  FIG. 5D shows the state of the black particle group 11K when the voltage −V1b is applied only to the pixel B at time t4 after the voltage applied to the image A and the pixel B is stopped at time t3. FIG. In this case, as shown in FIG. 5D, the black particle group 11K existing within the range covered by the electric field formed by the voltage −V1b adheres to the back substrate 2 side, while formed by the voltage −V1b. The black particle group 11K existing in a range where the electric field does not reach remains attached to the display substrate 1 side. That is, the display color of the pixel A is white, and the display color of the pixel B is black.

  When displaying black on the pixel A and white on the pixel B, the voltage −V1b is applied only to the pixel electrode 4B in the state of the black particle group 11K shown in FIG. The reason why the state of the black particle group 11K shown in FIGS. 5B and 5C is not used is that the reset voltage is applied to the black particle group 11K.

  The reset voltage is a voltage applied to each pixel before applying a voltage (drive voltage) corresponding to the display density of the black particle group 11K instructed as the color information of the image to the pixel electrode 4. Since the adhesion force of each black particle 11K to the pair of substrates 1 and 2 varies, the black particle group that adheres to one of the pair of substrates 1 and 2 by applying a reset voltage to each pixel in advance. 11K is peeled from the substrate at least once. By doing so, the variation in the movement start energy required for the separation of each black particle 11K is reduced, and the effect of suppressing the variation in the display density of the image displayed when the drive voltage is applied to each pixel is expected. .

  Specifically, in FIG. 4, the voltage from time t1 to time t3 is the reset voltage, and the voltage from time t4 to time t5 is the drive voltage.

  However, even when a reset voltage having the waveform shown in FIG. 4 is applied to each pixel, if different colors are displayed in adjacent pixels, such as pixel A and pixel B, they are displayed on each pixel. In some cases, the display density of an image varies.

  For example, in FIG. 5D, in order to display black in the image A and white in the pixel B, the drive voltage −V1b is applied only to the pixel electrode 4B, but the electric field formed by the voltage −V1b is only the pixel B. In some cases, the pixel A adjacent to the pixel B is also affected. In this case, under the influence of the electric field from the pixel B that attempts to attract the black particles 11K to the back substrate 2 side, the black particles 11K included in the pixel A that adheres to the display substrate 1 side more closely to the pixel B. The black particles 11 </ b> K located in a nearby place are peeled off from the display substrate 1 side and attached to the back substrate 2 side of the pixel B. Therefore, it is considered that the particle amount of the black particles 11K included in the pixel B is larger than the particle amount of the black particles 11K included in the pixel A, and the display density of the image between the pixels varies.

  Therefore, in the following description, the CPU 401 of the display device 100 according to the present embodiment reads a drive program for the display medium 10 and executes the drive program, thereby applying a reset voltage that suppresses variation in density between pixels of the display medium 10. Processing will be described.

  As an example, the drive program is preinstalled in the ROM 402 of the display device 100. However, the drive program is provided in a state stored in a computer-readable recording medium such as a CD-ROM, or wired Or the form etc. which are delivered via the communication means (not shown) by radio | wireless may be sufficient.

  First, with reference to FIG. 6, the operation of the display device 100 when executing the reset voltage application process according to the present embodiment will be described.

  FIG. 6 is a flowchart showing the flow of processing of the drive program for the display medium 10 executed by the CPU 401 of the display device 100 at this time. The drive program is displayed by the CPU 401 via a communication means (not shown), for example. This is executed by the CPU 401 every time an instruction to display an image on the medium 10 is received.

  As an example, the black particle group 11K in each pixel before the reset voltage application process shown in FIG. 6 is performed is attached to the display substrate 1 side as shown in FIG. And At this time, it is assumed that the voltage applied to the pixel electrode 4A and the pixel electrode 4B is the ground voltage, that is, 0V.

  First, in step S10, for example, color information of an image displayed on the display medium 10 is read for each pixel from image information received together with an image display instruction.

  Here, the color information of the image is information for uniquely specifying the display color for each pixel of the image, such as RGB data or CMY data, and the color information of the image in the present embodiment is, for example, a pixel It is assumed that a black density value is given every time. In order to simplify the description, in the following description, as an example, it is assumed that color information in which the black density value of the pixel A is 100% and the black density value of the pixel B is 0% is read.

  In step S20, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A is the voltage −V1b. At this time, the voltage applied to the pixel electrode 4B remains 0V.

  FIG. 7 is a diagram showing waveforms of voltages applied to the pixel electrodes 4 corresponding to the pixels A and B when the reset voltage application process shown in FIG. 6 is executed. ) Shows the waveform of the voltage applied to the pixel A, and FIG. 7B shows the waveform of the voltage applied to the pixel B. As shown in FIG. 7, by the process of step S20, for example, the applied voltage to the pixel electrode 4A at time t1 becomes the voltage −V1b, and the applied voltage to the pixel electrode 4B becomes 0V.

  FIG. 8 is a diagram showing the state of the black particle group 11K in each pixel when the reset voltage application process shown in FIG. 6 is executed.

  Before the reset voltage application process is executed, as shown in FIG. 8A, the black particle group 11K attached to the display substrate 1 side of the pixel A executes the process of step S20, so that FIG. As shown in (B), it is drawn toward the back substrate 2 side.

  In this case, as already described, the electric field formed by the voltage −V1b affects not only the pixel A but also the pixel B adjacent to the pixel A along the direction of the arrow R1, for example. Therefore, among the black particle group 11K included in the pixel B, the black particles 11K located closer to the pixel A are peeled off from the display substrate 1 side and moved to the back substrate 2 side of the pixel A. That is, the particle amount of the black particle group 11K included in the pixel A is larger than the particle amount of the black particle group 11K included in the pixel B.

  Next, in step S30, it is determined whether or not the voltage −V1b is applied to the pixel electrode 4A over a predetermined first frame number (shift frame number). When the determination is negative, the process of this step is repeated until the voltage −V1b is applied to the pixel electrode 4A by the number of frames shifted. And in affirmation determination, it transfers to step S40.

  As already described, the frame is a unit that represents the time required to sequentially apply a voltage to each of all the pixel electrodes 4 included in the display medium 10 when the pixel electrode 4 is a TFT electrode, for example. Note that the number of misaligned frames is stored in advance in a predetermined area of the nonvolatile memory 404, for example.

  As a result of the processing in this step, as shown in FIG. 7, the voltage applied to the pixel electrode 4A is maintained at the voltage −V1b over the period from time t1 to time t1 ′ corresponding to the number of shifted frames, and the pixel The applied voltage to the electrode 4B is maintained at 0V.

  In step S40, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4B becomes the voltage −V1b. At this time, the voltage applied to the pixel electrode 4A is kept at the voltage −V1b. As a result of the process in this step, as shown in FIG. 7, for example, the voltage applied to the pixel electrode 4A and the pixel electrode 4B at time t1 'becomes both the voltage -V1b.

  In step S50, it is determined whether or not the voltage −V1b is applied to the pixel electrode 4A and the pixel electrode 4B over a predetermined second frame number (white reset frame number). If the determination is negative, the process in this step is repeated until the voltage −V1b is applied to the pixel electrode 4A and the pixel electrode 4B by the number of white reset frames. And in affirmation determination, it transfers to step S60.

  Through the processing in this step, as shown in FIG. 7, the voltage applied to the pixel electrode 4A and the pixel electrode 4B is maintained at the voltage −V1b over a period from time t1 ′ corresponding to the number of white reset frames to time t2. Is done.

  In addition, as a result of the processing in this step, as shown in FIG. 8C, the black particle group 11K of each pixel adheres to the back substrate 2 side, and both the pixel A and the pixel B display white. In this way, driving the black particle group 11K of the display medium 10 by controlling the voltage applied to the pixel electrode 4 so that the display color of each pixel becomes white is called white reset driving.

  Next, in step S60, the voltage application unit 30 is controlled so that the applied voltage to the pixel electrode 4A is 0 V and the applied voltage to the pixel electrode 4B is the voltage V1b.

  Through the processing in this step, as shown in FIG. 7, the voltage applied to the pixel electrode 4B at time t2 becomes the voltage V1b, and the voltage applied to the pixel electrode 4A becomes 0V.

  Further, as a result of the processing in this step, as shown in FIG. 8D, the black particle group 11K of the pixel B moves to the display substrate 1 side. In this case, the electric field formed by the voltage V1b affects not only the pixel B but also the pixel A adjacent to the pixel B, for example, along the arrow R2 direction. Accordingly, among the black particle group 11K included in the pixel B, the black particles 11K positioned closer to the pixel A move to the display substrate 1 side of the pixel A, not to the display substrate 1 side of the pixel B. That is, while maintaining the magnitude relationship of the particle amount of the black particle group 11K included in the pixel A> the particle amount of the black particle group 11K included in the pixel B, the particle amount of the black particle group 11K included in the pixel A is When the processing in step S30 is completed, the amount of particles is larger than the amount of particles of the black particle group 11K included in the pixel A.

  Next, in step S70, it is determined whether or not the voltage V1b is applied to the pixel electrode 4B over the number of shifted frames. If the determination is negative, the process in this step is repeated until the voltage V1b is applied to the pixel electrode 4B by the number of frames that are shifted. And in affirmation determination, it transfers to step S80.

  By the processing in this step, as shown in FIG. 7, the voltage applied to the pixel electrode 4B is maintained at the voltage V1b over the period from time t2 to time t2 ′ corresponding to the number of shifted frames, and the pixel electrode The applied voltage to 4A is maintained at 0V.

  In step S80, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A is the voltage V1b. At this time, the voltage applied to the pixel electrode 4B continues to be the voltage V1b. By the processing in this step, as shown in FIG. 7, for example, the voltage applied to the pixel electrode 4A and the pixel electrode 4B at time t2 'becomes the voltage V1b.

  In step S90, it is determined whether or not the voltage V1b is applied to the pixel electrode 4A and the pixel electrode 4B over a predetermined third number of frames (number of black reset frames).

  If the determination is negative, the process in this step is repeated until the voltage V1b is applied to the pixel electrode 4A and the pixel electrode 4B by the number of black reset frames. And in affirmation determination, it transfers to step S100.

  Through the processing in this step, as shown in FIG. 7, the voltage applied to the pixel electrode 4A and the pixel electrode 4B is maintained at the voltage V1b over a period from time t2 ′ to time t3 corresponding to the number of black reset frames. The

  In addition, as a result of the processing in this step, as shown in FIG. 8E, the black particle group 11K of each pixel adheres to the display substrate 1 side, and both the pixel A and the pixel B display black. In this way, driving the black particle group 11K of the display medium 10 by controlling the voltage applied to the pixel electrode 4 so that the display color of each pixel becomes black is called black reset driving.

  In step S100, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A and the pixel electrode 4B is 0V.

  As described above, the reset voltage application process illustrated in FIG. 6 causes the amount of the black particle group 11K included in the pixel A to be greater than the amount of the black particle group 11K included in the pixel B.

  Next, the situation of the black particle group 11K in each pixel when displaying an image in which the pixel A is black and the pixel B is white after the reset voltage application process is completed will be described.

  In this case, in order to set the display color of the pixel B to white, as shown in FIG. 7, for example, the voltage −V1b is applied to the pixel electrode 4B over a period from time t4 to time t5. When the voltage −V1b is applied to the pixel electrode 4B, the black particle group 11K included in the pixel B is peeled off from the display substrate 1 side and moved to the back substrate 2 side as shown in FIG. As already described, the electric field formed by the voltage −V1b affects not only the pixel B but also the pixel A adjacent to the pixel B along the direction of the arrow R3, for example. Therefore, among the black particle group 11K included in the pixel A adhering to the display substrate 1 side, the black particles 11K located closer to the pixel B are peeled off from the display substrate 1 side to the back substrate 2 side of the pixel B. Moving.

  That is, the black particles 11K included in the pixel A move to the pixel B by applying a driving voltage for displaying an image according to the image information. However, after the reset voltage application process shown in FIG. 6 is performed, the amount of particles of the black particle group 11K included in the pixel A is larger than the amount of particles of the black particle group 11K included in the pixel B. Therefore, even when a driving voltage is applied to the pixel B, the variation in the amount of particles of the black particle group 11K included in the pixel A and the pixel B can be suppressed within a predetermined range (see FIG. 8G). Variations in the display density of the image during this period are suppressed.

  FIG. 9 shows experimental results when the reset voltage application process shown in FIG. 6 is performed. In FIG. 9A, for example, like the voltage waveform shown in FIG. 4, the application timing of the reset voltage applied to each pixel is aligned, and an image corresponding to the image information is obtained up to a predetermined number of times. FIG. 4 is a diagram illustrating an example of an image displayed on the display medium 10 when repeatedly displayed.

  On the other hand, in FIG. 9B, for example, as in the voltage waveform shown in FIG. 7, the reset voltage application timing in the white reset drive and the reset voltage application timing in the black reset drive are different between adjacent pixels. Furthermore, FIG. 5 is a diagram illustrating an example of an image displayed on the display medium 10 when an image corresponding to image information is repeatedly displayed up to a predetermined number of times.

  The image of FIG. 9A has thinner image lines than the image of FIG. 9B, and it is recognized that the image may be blurred depending on the location.

  On the other hand, the image of FIG. 9B has less variation in display density of the image than the image of FIG. 9A, and it can be seen that the clarity of the image is improved.

  Specifically, for example, after aligning the application timing of the reset voltage applied to the pixel electrode 4 of each pixel, the average optical density after displaying the line of one pixel width 10 times on the display medium 10 is displayed. After the rate of change (average OD rate of change) is 7.8%, the reset voltage application process in the present embodiment is executed, and a line of 1 pixel width is displayed 10 times on the display medium 10 repeatedly. The average OD change rate was 2.7%.

  Furthermore, the inventors evaluated the influence of the number of misaligned frames in the processing of step S30 and step S70 on the amount of movement of the black particles 11K between pixels.

  Table 1 shows the average OD change after displaying an image displaying a different display color in adjacent pixels once using a combination of the number of shift frames in the white reset drive and the number of shift frames in the black reset drive. It is a table showing a rate. Note that one frame in this embodiment corresponds to about 40 ms.

  FIG. 10 is a graph showing the evaluation results in Table 1 with the average OD change rate on the vertical axis and the number of shifted frames on the horizontal axis.

  From the evaluation results shown in Table 1 and FIG. 10, when the number of misaligned frames during black reset driving is set to 0, that is, the reset voltage application timing applied to the pixel electrode 4 during black reset driving is aligned for each pixel. Thus, looking at the average OD change rate when only the number of shifted frames in white reset driving is changed, the maximum is 2.1% when the number of shifted frames is four.

  On the other hand, when the number of misaligned frames at the time of white reset driving is set to 0, that is, after the reset voltage application timing applied to the pixel electrode 4 in white reset driving is aligned for each pixel, black reset driving is performed. Looking at the average OD change rate when only the number of misaligned frames is changed, the maximum is 6.5% when the number of misaligned frames is six.

  From the above results, the application timing of the reset voltage applied to each of the adjacent pixels during the black reset driving rather than shifting the application timing of the reset voltage applied to each of the adjacent pixels during the white reset driving. It can be seen that the degree of influence on the amount of movement of the black particles 11K between the pixels is larger when the position is shifted. That is, the degree of influence of the process of step S70 on the amount of movement of the black particles 11K between the pixels is greater than that of the process of step S30.

  Therefore, for example, in both the reset driving of the white reset driving and the black reset driving, the reset voltage applied to each of the adjacent pixels at least in the black reset driving without executing the voltage application sequence considering the number of shifted frames. If the application timing is shifted, an effect of suppressing variations in image display density when a drive voltage is applied is expected.

  Further, it can be seen from the evaluation results of Table 1 and FIG. 10 that the amount of movement of the black particles 11K between the pixels tends to increase as the number of shifted frames increases.

  Therefore, for example, as shown in FIG. 8F, when the drive voltage −V1b is applied to the pixel B so that the display color of the pixel A is black and the display color of the image B is white, the display is performed on the pixel B. It is necessary to form a stronger electric field in the pixel B and move more black particles 11K from the display substrate 1 side to the back substrate 2 side as the power white display density becomes higher. Along with this, the particle amount of the black particle group 11K moving from the pixel A to the pixel B also increases.

Therefore, in this case, in order to suppress variations in the display density of the image between the pixels after the drive voltage is applied, the number of shifted frames is increased in the reset voltage application process of FIG. The amount of the particles 11K may be increased.

  In the reset voltage application process of FIG. 6, as shown in FIG. 7, the reset voltage applied to the pixel A during the period from time t1 to time t1 ′ (white reset deviation period) formed by the process of step S30. The magnitude of (initial reset voltage) was set to the same magnitude as the reset voltage applied to the pixel A during the period from time t1 ′ to time t2 (white reset common period).

  However, it is not necessary to make the magnitude of the reset voltage applied to the pixel A common in the white reset shift period and the white reset common period.

  Similarly, in the reset voltage application process of FIG. 6, as shown in FIG. 7, in the period from time t2 to time t2 ′ formed by the process of step S70 (black reset deviation period), the initial application to the pixel B is performed. The magnitude of the reset voltage is the same as the reset voltage applied to the pixel B during the period from time t2 ′ to time t3 (black reset common period).

  However, it is not necessary to make the magnitude of the reset voltage applied to the pixel B common in the black reset shift period and the black reset common period. The white reset shift period and the black reset shift period may be collectively referred to simply as “shift period”.

  Therefore, the inventors apply different voltages to the pixel electrode 4A of the pixel A during the white reset shift period and the white reset common period, and also apply a black voltage to the pixel electrode 4B of the pixel B, as shown in FIG. Different voltages were applied in the reset deviation period and the black reset common period, and the influence of the initial reset voltage on the amount of movement of the black particles 11K between the pixels was evaluated.

  In this evaluation, as an example, both the number of shift frames in the white reset drive and the number of shift frames in the black reset drive are set to two frames. Further, after the absolute value of the reset voltage in the white reset common period and the black reset common period is set to 30 V, the absolute value of the initial reset voltage is changed to 10 V, 20 V, and 30 V, and the image is displayed once. The average OD change rate was compared.

  FIG. 12 shows the evaluation results in a graph with the average OD change rate on the vertical axis and the number of shifted frames on the horizontal axis.

  From the evaluation results in FIG. 12, it can be seen that the degree of influence on the amount of movement of the black particles 11K between the pixels increases as the initial reset voltage increases.

  Therefore, for example, as shown in FIG. 8F, when the drive voltage −V1b is applied to the pixel B so that the display color of the pixel A is black and the display color of the image B is white, the display is performed on the pixel B. It is necessary to form a stronger electric field in the pixel B and move more black particles 11K from the display substrate 1 side to the back substrate 2 side as the power white display density becomes higher. Accordingly, as the white display density to be displayed on the pixel B increases, the amount of particles of the black particle group 11K that moves from the pixel A to the pixel B also increases.

Therefore, in this case, in order to suppress the variation in the display density of the image between the pixels after the drive voltage is applied, the black voltage included in the pixel A is increased by increasing the initial reset voltage in the reset voltage application process of FIG. The amount of the particles 11K may be increased.

  Furthermore, the inventors evaluated the influence of the number of misaligned frames and the initial reset voltage on the amount of movement of the black particles 11K between the pixels in the reset voltage application processing in the present embodiment.

  In this evaluation, as an example, both the number of shift frames in the white reset drive and the number of shift frames in the black reset drive are set to two frames. In addition, the absolute value of the reset voltage in the white reset common period and the black reset common period was set to 30 V, and the absolute value of the initial reset voltage was changed to 10 V, 20 V, and 30 V. Then, after the black line of 1 pixel width was repeated 10 times and displayed on the display medium 10, the average OD change rate between the density of the first line and the density of the 10th line was evaluated.

  FIG. 13 is a graph in which the evaluation results are represented by the average OD change rate on the vertical axis and the number of shifted frames on the horizontal axis. Note that “the number of shift frames is positive” means that the application timing of the reset voltage applied to the adjacent pixels is the timing shown in FIG. Specifically, the timing at which the initial reset voltage in the white reset driving is applied to the pixel A before the pixel B and the initial reset voltage in the black reset driving is applied to the pixel B before the pixel A is positive. The minus number of shift frames means an application timing opposite to the application timing of the initialization reset voltage shown in FIG.

  From the evaluation results shown in FIG. 13, when both the number of misaligned frames in white reset driving and the number of misaligned frames in black reset driving are two frames, the display density between pixels can be increased by setting the initialization reset voltage to 20V. It can be seen that the variation is suppressed.

  This is because the black particles 11K returned to the pixels displaying the line when the absolute value of the initial reset voltage is set to 30 V when the number of shift frames in the white reset drive and the number of shift frames in the black reset drive are both two frames. On the contrary, if the absolute value of the initial reset voltage is 10 V, it is presumed that the amount of black particles 11K returned to the pixels displaying the line is insufficient.

  As described above, according to this embodiment, when displaying different display colors in each of the adjacent pixels, before applying the driving voltage for displaying the image according to the instructed image information, each of the adjacent pixels is displayed. The application timing of the reset voltage to be applied was shifted.

  Thereby, the amount of particles contained in each of the adjacent pixels is individually adjusted, and an image corresponding to the image information is displayed. Therefore, even when the drive voltage is applied to one of the adjacent pixels, the adjacent pixels are adjacent to each other. The amount of particles contained in each pixel is now within a predetermined range. Therefore, even if an image is repeatedly displayed on the display medium 10, an effect of suppressing variation in density between pixels is expected.

  The black particle group 11K of the present embodiment has been described as being charged on the positive electrode, but may be charged on the negative electrode. When the black particle group 11K is charged to the negative electrode, the waveform of the voltage applied to the pixel electrode 4 may be, for example, the polarity of the voltage waveform shown in FIG.

Second Embodiment

  Next, the operation of the display device 100 when executing the reset voltage application process according to the second embodiment of the present invention will be described.

  In the first embodiment, in each pixel, the particle group that moves between the substrates 1 and 2 according to the electric field formed between the pair of substrates 1 and 2 is one type of the black particle group 11K. In the second embodiment, a reset voltage application process when each pixel includes two types of particle groups charged to the same polarity will be described.

  FIG. 14 is a diagram schematically showing the display device 100 according to the second embodiment. A difference from the display device 100 of FIG. 1 in the first embodiment is that a cyan particle group 11C and a red particle group 11R are included in the dispersion medium 6 of each pixel instead of the black particle group 11K. Other configurations are the same as those of the first embodiment.

  In this embodiment, the cyan particle group 11C and the red particle group 11R are both charged to the positive electrode, but the cyan particle group 11C and the red particle group 11R may be charged to the same polarity. Both may be charged to the negative electrode. Moreover, there is no restriction | limiting in the particle size and color of cyan particle group 11C and red particle group 11R, What is necessary is just to set suitably according to the responsiveness of particle group 11, the display color of an image, etc. Moreover, although the red particle group 11R in this embodiment is demonstrated as what has translucency as an example, there is no restriction | limiting regarding the translucency of the particle group 11. FIG.

  FIG. 15 shows threshold characteristics of each particle group 11 in the display device 100 according to the present embodiment.

  In FIG. 15, the threshold characteristic of the cyan particle group 11C is represented by a characteristic 50C, and the threshold characteristic of the red particle group 11R is represented by a characteristic 50R.

  In the cyan particle group 11C, when a voltage exceeding the threshold value V1a is applied to the pixel electrode 4, the cyan particle group 11C attached to the back substrate 2 side peels from the back substrate 2 side, and the substrates 1, 2 It moves to the display substrate 1 side according to the electric field formed therebetween. Further, when a voltage less than the threshold value −V1a is applied to the pixel electrode 4, the cyan particle group 11C peels off from the display substrate 1 side, and the cyan particle group 11C attached to the display substrate 1 side peels off. It moves to the back substrate 2 side according to the electric field formed between 1 and 2.

  On the other hand, in the red particle group 11R, when a voltage exceeding the threshold V2a is applied to the pixel electrode 4, the red particle group 11R attached to the back substrate 2 side begins to peel from the back substrate 2 side, and the substrates 1, 2 It moves to the display substrate 1 side according to the electric field formed therebetween. In addition, when a voltage less than the threshold value −V2a is applied to the pixel electrode 4, the red particle group 11R starts to peel from the display substrate 1 side when the red particle group 11R attached to the display substrate 1 side. It moves to the back substrate 2 side according to the electric field formed between the two.

  In addition, regarding the magnitude of the threshold value of the cyan particle group 11C and the red particle group 11R, it is assumed that | V1a | <| V1 | <| V2a | <| V2 | It is not limited to this.

  FIG. 16 is a flowchart showing the flow of the process of the display medium 10 drive program executed by the CPU 401 of the display device 100 when executing the reset voltage application process according to the present embodiment. The drive program is executed by the CPU 401 every time the CPU 401 receives an image display instruction on the display medium 10 via a communication unit (not shown), for example.

  First, in step S15, the reset voltage application process (first reset process) shown in FIG. 6 is executed. At this time, the magnitude of the reset voltage in the white reset driving is set to a magnitude of a voltage for moving both the cyan particle group 11C and the red particle group 11R, for example, a voltage −V2b which is a voltage equal to or lower than the voltage −V2. Similarly, the magnitude of the reset voltage in the black reset driving is, for example, the voltage V2b that is a voltage equal to or higher than the voltage V2.

  FIGS. 17A to 17D are diagrams illustrating states of the cyan particle group 11C and the red particle group 11R in each pixel when the first reset process is executed. In this case, the cyan particle group 11C and the red particle group 11R show the same movement as the black particle group 11K in the first embodiment shown in FIG.

After completion of the first reset process, as shown in FIG. 17E, the cyan particle group 11C and the red particle group 11R included in the pixel A have the same amount of particles as the cyan particle group 11C included in the pixel B. And more than the amount of particles of the red particle group 11R.

  In step S <b> 25, the voltage application unit 30 is controlled so that a drive voltage that causes the display color of the pixel A to be black and the display color of the pixel B to be white is applied to the pixel electrode 4. Specifically, the voltage application unit 30 is controlled so that the drive voltage −V2b is applied to the pixel electrode 4B.

  When the voltage −V2b is applied to the pixel electrode 4B, the cyan particle group 11C and the red particle group 11R included in the pixel B, and part of the cyan particle group 11C and the red particle group 11R included in the pixel A are displayed. As shown in FIG. 17F, the particles are peeled off from the display substrate 1 side and moved to the back substrate 2 side of the pixel B.

  As a result, as already described in the first embodiment, the variation in the amount of particles of the cyan particle group 11C and the red particle group 11R included in the pixel A and the pixel B is suppressed within a predetermined range. At this time, the pixel A is black and the pixel B is white (see FIG. 17G).

  Next, in step S35, it is determined whether or not the display color displayed in each of the adjacent pixels read in the process of step S15 is a combination of white and black. In the case of an affirmative determination, since one of the adjacent pixels has already been displayed in white and the other in black by the processing in step 15 and step S25, the reset voltage application processing is terminated. On the other hand, if a negative determination is made, the process proceeds to step S45.

  In step S45, a reset voltage application process (second reset process) is executed for setting the display color to be displayed on each adjacent pixel to other than the combination of white and black. In the second reset process in the present embodiment, for example, a reset voltage application process is executed when an instruction to display an image in which the pixel A is red and the image B is cyan is received.

  For this purpose, in the second reset process, the same process as the first reset process is performed on the cyan particle group 11C having a lower threshold value. The particle amount of the cyan particle group 11C adhering to the display substrate 1 side of the pixel B is previously set larger than the particle amount of the cyan particle group 11C adhering to the display substrate 1 side of the pixel A.

  FIG. 18 is a flowchart showing the flow of the second reset process executed by the CPU 401.

  First, in step S200, in order to move the cyan particle group 11C included in the pixel A and the pixel B to the display substrate 1 side, the voltage applied to the pixel electrode 4A and the pixel electrode 4B is set to voltage V1 ≦ voltage V1c <voltage V2a. The voltage application unit 30 is controlled so as to be the voltage V1c.

  By the processing in this step, as shown in FIG. 19A, the cyan color particle group 11C included in the pixel A and the pixel B adheres to the display substrate 1 side. Then, after a sufficient period of time for the cyan particle group 11C to adhere to the display substrate 1 side, the voltage application unit 30 is controlled so as to stop the voltage applied to the pixel electrode 4A and the pixel electrode 4B.

  In step S210, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4B satisfies the voltage −V1c where the voltage −V2a <voltage−V1c ≦ the voltage −V1. At this time, the voltage applied to the pixel electrode 4A is kept at 0V.

  Before the execution of this step, as shown in FIG. 19A, the cyan particle group 11C attached to the pixel B on the display substrate 1 side executes the processing of this step, so that FIG. As shown in B), it is drawn toward the back substrate 2 side.

  In this case, as already described, the electric field formed by the voltage −V1c affects not only the pixel B but also the pixel A adjacent to the pixel B along the direction of the arrow R4, for example. Accordingly, among the cyan particle group 11C included in the pixel A, the cyan particle 11C located closer to the pixel B is peeled off from the display substrate 1 side and moved to the rear substrate 2 side of the pixel B. That is, the particle amount of the cyan particle group 11C included in the pixel B is larger than the particle amount of the cyan particle group 11C included in the pixel A.

  Next, in step S220, it is determined whether or not the voltage −V1c has been applied to the pixel electrode 4B over a predetermined number of shift frames. If the determination is negative, the process of this step is repeated until the voltage −V1c is applied to the pixel electrode 4B by the number of frames that are shifted. And in affirmation determination, it transfers to step S230.

  In step S230, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A is the voltage −V1c. At this time, the voltage applied to the pixel electrode 4B continues to be the voltage −V1c.

  In step S240, it is determined whether or not the voltage −V1c is applied to the pixel electrode 4A and the pixel electrode 4B over a predetermined number of frames (the number of cyan reset frames). If the determination is negative, the process in this step is repeated until the voltage −V1c is applied to the pixel electrode 4A and the pixel electrode 4B by the number of cyan reset frames. And in affirmation determination, it transfers to step S250.

  As a result of the processing in this step, as shown in FIG. 19C, the cyan particle group 11C of each pixel is attached to the back substrate 2 side, and the pixel A displays red and the pixel B displays white.

  Next, in step S250, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4B is 0 V and the voltage applied to the pixel electrode 4A is the voltage V1c.

  By the processing in this step, the cyan particle group 11C of the pixel A moves to the display substrate 1 side as shown in FIG. In this case, the electric field formed by the voltage V1c affects not only the pixel A but also the pixel B adjacent to the pixel A along the direction of the arrow R5, for example. Accordingly, among the cyan particle group 11C included in the pixel A, the cyan particle 11C located closer to the pixel B moves to the display substrate 1 side of the pixel B, not to the display substrate 1 side of the pixel A. . That is, the particle size of the cyan particle group 11C included in the pixel B is maintained while maintaining the magnitude relationship of the particle amount of the cyan particle group 11C included in the pixel B> the particle amount of the cyan color group 11C included in the pixel A. The amount is further larger than the particle amount of the cyan particle group 11C included in the pixel B when the process of step S220 is completed.

  Next, in step S260, it is determined whether or not the voltage V1c is applied to the pixel electrode 4A over the number of shift frames. If the determination is negative, the process in this step is repeated until the voltage V1c is applied to the pixel electrode 4A by the number of frames shifted. And in affirmation determination, it transfers to step S270.

  In step S270, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4B becomes the voltage V1c. At this time, the voltage applied to the pixel electrode 4A remains at the voltage V1c.

  In step S280, it is determined whether or not the voltage V1c is applied to the pixel electrode 4A and the pixel electrode 4B over the number of cyan reset frames.

  If the determination is negative, the process of this step is repeated until the voltage V1c is applied to the pixel electrode 4A and the pixel electrode 4B by the number of cyan reset frames. And in affirmation determination, it transfers to step S290.

  By the processing in this step, as shown in FIG. 19E, the cyan particle group 11C of each pixel is attached to the display substrate 1, and the pixel A displays black and the pixel B displays cyan.

  In step S290, the voltage application unit 30 is controlled so that the applied voltage to the pixel electrode 4A and the pixel electrode 4B becomes 0 V, and the application of the reset voltage to the pixel A and the pixel B is stopped.

  As described above, the cyan particle group 11C attached to the pixel A on the display substrate 1 side is larger in the amount of the cyan particle group 11C attached to the pixel B on the display substrate 1 side by the second reset processing shown in FIG. More than the amount of particles.

  In step S55 of FIG. 16, the voltage application unit 30 is controlled so that the drive voltage −V1c is applied to the pixel electrode 4A. By the processing in this step, the cyan particle group 11C included in the pixel A is peeled off from the display substrate 1 side and moved to the back substrate 2 side as shown in FIG. Further, the electric field formed by the voltage −V1c affects not only the pixel A but also the pixel B adjacent to the pixel A along the direction of the arrow R6, for example.

  Therefore, among the cyan particle group 11C included in the pixel B attached to the display substrate 1 side, the cyan particle 11C positioned closer to the pixel A is peeled off from the display substrate 1 side, and the rear substrate 2 of the pixel A Move to the side.

  However, due to the processing in step S45, the amount of particles of the cyan particle group 11C attached to the pixel B on the display substrate 1 side is larger than the amount of particles of the cyan particle group 11C attached to the pixel A on the display substrate 1 side. Yes. Therefore, by applying the drive voltage, the variation in the particle amount of the cyan particle group 11C included in the pixel A and the pixel B is suppressed within a predetermined range, and the variation in the display density of the image between the pixels is suppressed. Will be.

  As described above, in the present embodiment, even when two types of particle groups 11 that are charged to the same polarity are sealed in the display medium 10, the adjacent pixel groups 11 are displayed according to the display color to be displayed on the display medium 10. By changing the application sequence of the reset voltage applied to each pixel, even if an image displaying a different display color is repeatedly displayed on each adjacent pixel, variation in density between pixels is suppressed.

  Specifically, when white and black are displayed by adjacent pixels, processing similar to the reset voltage application processing in the first embodiment is executed. Further, when displaying a combination other than white and black in adjacent pixels, the same process as the reset voltage application process in the first embodiment is performed before the drive voltage application in each of steps S25 and S55.

  Thereby, the amount of particles contained in each of the adjacent pixels is individually adjusted, and an image corresponding to the image information is displayed. Therefore, even when the drive voltage is applied to one of the adjacent pixels, the adjacent pixels are adjacent to each other. The amount of particles contained in each pixel falls within a predetermined range. Therefore, even if an image is repeatedly displayed on the display medium 10, an effect of suppressing variation in density between pixels is expected.

  As in the first embodiment, for the reset voltage application processing in this embodiment, by adjusting at least one of the number of shifted frames and the initial reset voltage according to the display density of the image to be displayed on the pixel. Therefore, an effect of further suppressing variation in density between pixels is expected.

<Third Embodiment>

  Next, the operation of the display device 100 when executing the reset voltage application process according to the third embodiment of the present invention will be described.

  In the second embodiment, in each pixel, the particle group that moves between the substrates 1 and 2 according to the electric field formed between the pair of substrates 1 and 2 is the cyan particle group 11C and the red color that are charged to the same polarity. It was particle group 11R. In the third embodiment, a reset voltage application process when each pixel includes two types of particle groups charged to different polarities will be described.

  The display device 100 in the third embodiment is different from the display device 100 in the second embodiment in that the cyan particle group 11C is charged to the negative electrode and the red particle group 11R is charged to the positive electrode. The configuration is the same as that of the display device 100 shown in FIG.

  The cyan particle group 11C and the red particle group 11R need only be charged to different polarities, and the cyan particle group 11C may be charged to the positive electrode and the red particle group 11R may be charged to the negative electrode.

  FIG. 20 shows threshold characteristics of each particle group 11 in the display device 100 according to the present embodiment.

  In the cyan particle group 11C, when a voltage exceeding the threshold value V1a is applied to the pixel electrode 4, the cyan particle group 11C attached to the display substrate 1 side peels from the display substrate 1 side, and the substrates 1, 2 It moves to the back substrate 2 side according to the electric field formed therebetween. Further, when the cyan particle group 11C is applied with a voltage less than the threshold value −V1a to the pixel electrode 4, the cyan particle group 11C attached to the back substrate 2 side peels off from the back substrate 2 side, and the substrate It moves to the display substrate 1 side according to the electric field formed between 1 and 2.

  On the other hand, in the red particle group 11R, when a voltage exceeding the threshold V2a is applied to the pixel electrode 4, the red particle group 11R attached to the back substrate 2 side begins to peel from the back substrate 2 side, and the substrates 1, 2 It moves to the display substrate 1 side according to the electric field formed therebetween. In addition, when a voltage less than the threshold value −V2a is applied to the pixel electrode 4, the red particle group 11R starts to peel from the display substrate 1 side when the red particle group 11R attached to the display substrate 1 side. It moves to the back substrate 2 side according to the electric field formed between the two.

  In addition, regarding the magnitude of the threshold value of the cyan particle group 11C and the red particle group 11R, it is assumed that | V1a | <| V1 | <| V2a | <| V2 | It is not limited to this.

  FIG. 21 is a flowchart showing the flow of the process of the display medium 10 drive program executed by the CPU 401 of the display device 100 when executing the reset voltage application process according to the present embodiment. The drive program is executed by the CPU 401 every time the CPU 401 receives an image display instruction on the display medium 10 via a communication unit (not shown), for example.

  In the following description, it is assumed that the cyan particle group 11C is attached in advance to the back substrate 2 side and the red particle group 11R is attached in advance to the display substrate 1 side.

  First, in step S15, the first reset process shown in FIG. 6 is executed. At this time, the magnitude of the reset voltage −V1b in the white reset driving is replaced with a voltage magnitude that moves the cyan particle group 11C and the red particle group 11R together, for example, a voltage −V2b that is a voltage equal to or lower than the voltage −V2. . Similarly, the magnitude of the reset voltage V1b in the black reset driving is replaced with, for example, a voltage V2b that is a voltage equal to or higher than the voltage V2.

  FIG. 23 is a diagram illustrating a state of the cyan particle group 11C and the red particle group 11R in each pixel when the first reset process is executed in the present embodiment.

  FIG. 23A is a diagram showing the arrangement of the particle groups 11 before the processing in step S15.

  FIG. 23B is a diagram showing the state of each particle group 11 when the voltage −V2b is applied to the pixel electrode 4A in the process of step S20 of FIG. In this case, as already described, the electric field formed by the voltage −V2b affects not only the pixel A but also the pixel B adjacent to the pixel A along the directions of the arrows R7 and R8, for example.

  Therefore, among the red particle group 11R included in the pixel B, the red particle 11R located closer to the pixel A is peeled off from the display substrate 1 side and moves to the back substrate 2 side of the pixel A.

  Further, among the cyan color particle group 11C included in the pixel A, the cyan color particle 11C positioned closer to the pixel B moves to the display substrate 1 side of the pixel B instead of the display substrate 1 side of the pixel A. .

  That is, the particle amount of the red particle group 11R included in the pixel A is larger than the particle amount of the red particle group 11R included in the pixel B, while the particle amount of the cyan particle group 11C included in the pixel B is larger. This is larger than the particle amount of the cyan particle group 11C included in the pixel A.

  FIG. 23C is a diagram showing a state of each particle group 11 when the process of step S50 of FIG. 6 is completed. In this case, unlike the display medium 10 in the first embodiment, each pixel of the display medium 10 displays a cyan color. In this way, by controlling the voltage applied to the pixel electrode 4, driving the cyan particle group 11C and the red particle group 11R of the display medium 10 so that the display color of each pixel becomes cyan is cyan reset driving. That's it.

  FIG. 23D is a diagram showing the state of each particle group 11 when 0 V is applied to the pixel electrode 4A and voltage V2b is applied to the pixel electrode 4B in the process of step S60 of FIG.

  In this case, the electric field formed by the voltage V2b affects not only the pixel B but also the pixel A adjacent to the pixel B along, for example, the directions of the arrows R9 and R10.

  Therefore, among the red particle group 11R included in the pixel B, the red particle 11R located closer to the pixel A moves to the display substrate 1 side of the pixel A, not to the display substrate 1 side of the pixel B.

  Further, among the cyan particle group 11C included in the pixel A, the cyan particle 11C located closer to the pixel B is peeled off from the display substrate 1 side and moved to the rear substrate 2 side of the pixel B.

  FIG. 23E is a diagram showing the state of each particle group 11 when the process of step S90 of FIG. 6 is completed. In this case, for the reason described above, the pixel A includes a larger number of red particle groups 11R than the pixel A in FIG. 23C, and the pixel B is compared to the pixel B in FIG. And an even larger number of cyan particle groups 11C.

  In step S <b> 24, the voltage application unit 30 is controlled so that the drive voltage that applies the display color at the pixel A to red and the display color at the pixel B to cyan is applied to the pixel electrode 4. Specifically, the voltage application unit 30 is controlled so that the drive voltage −V2b is applied to the pixel electrode 4B while the drive voltage to the pixel electrode 4A is kept at 0V.

  When the voltage −V2b is applied to the pixel electrode 4B, some particles of the cyan particle group 11C included in the pixel B move to the pixel A, and some particles of the red particle group 11R included in the pixel A move. Moving to the pixel B, the pixel A is red and the pixel B is cyan. Accordingly, as shown in FIG. 23F, the variation in the amount of particles of the cyan particle group 11C and the red particle group 11R included in the pixel A and the pixel B is suppressed within a predetermined range.

  Next, in step S34, it is determined whether or not the display color displayed in each of the adjacent pixels read in the process of step S15 is a combination of white and black. In the case of negative determination, the reset voltage application process ends because one of the adjacent pixels has already displayed red and the other has cyan in the process of step 15 and step S24. On the other hand, if the determination is affirmative, the process proceeds to step S44.

  In step S44, a reset voltage application process (third reset process) is executed to set the display color displayed on each of the adjacent pixels to a combination of white and black. In the third reset process according to the present embodiment, for example, a reset voltage application process is executed when an instruction to display an image in which the pixel A is black and the image B is white is received.

Therefore, in the third reset process, a process similar to the first reset process of FIG. 6 is performed on the cyan particle group 11C having a lower threshold value, and is attached to the display substrate 1 side of the pixel A, for example. The particle amount of the cyan particle group 11C to be set is made larger in advance than the particle amount of the cyan particle group 11C attached to the display substrate 1 side of the pixel B.

  FIG. 22 is a flowchart showing the flow of the third reset process executed by the CPU 401.

  First, in step S300, in order to move the cyan particle group 11C included in the pixel A and the pixel B to the display substrate 1 side, the voltage applied to the pixel electrode 4A is voltage −V2a <voltage−V1c ≦ voltage−V1. The voltage application unit 30 is controlled so as to have a certain voltage −V1c.

  By the processing in this step, as shown in FIG. 24A, cyan particle group 11C included in pixel A adheres to the display substrate 1 side. Then, after a period sufficient for the cyan color particle group 11C to adhere to the display substrate 1 side, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A is stopped.

  In step S310, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A satisfies the voltage V1c where the voltage V1 ≦ the voltage V1c <the voltage V2a. At this time, the voltage applied to the pixel electrode 4B remains 0V.

  Before execution of this step, as shown in FIG. 24A, the cyan particle group 11C attached to the display substrate 1 side of the pixel A and the display substrate of the pixel B located closer to the pixel A A part of the cyan particle group 11C adhering to the 1 side is pulled toward the back substrate 2 side of the pixel A as shown in FIG. Therefore, the particle amount of the cyan particle group 11C included in the pixel A is larger than the particle amount of the cyan particle group 11C included in the pixel B.

  Next, in step S320, it is determined whether or not the voltage V1c is applied to the pixel electrode 4A over a predetermined number of shift frames. If the determination is negative, the process in this step is repeated until the voltage V1c is applied to the pixel electrode 4A by the number of frames shifted. And in affirmation determination, it transfers to step S330.

  In step S330, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4B becomes the voltage V1c. At this time, the voltage applied to the pixel electrode 4A remains at the voltage V1c.

  In step S340, it is determined whether or not the voltage V1c is applied to the pixel electrode 4A and the pixel electrode 4B over the number of cyan reset frames. If the determination is negative, the process of this step is repeated until the voltage V1c is applied to the pixel electrode 4A and the pixel electrode 4B by the number of cyan reset frames. And in affirmation determination, it transfers to step S350.

  By the processing in this step, as shown in FIG. 24C, the cyan color particle group 11C of each pixel is attached to the back substrate 2 side, and the pixel A displays red and the pixel B displays white.

  Next, in step S350, the voltage application unit 30 is controlled so that the applied voltage to the pixel electrode 4A is 0 V and the applied voltage to the pixel electrode 4B is the voltage −V1c.

  As a result of the processing in this step, as shown in FIG. 24D, the cyan particle group 11C attached to the back substrate 2 side of the pixel B due to the influence of the electric field formed by the voltage −V1c is The movement begins to be divided into the display substrate 1 side and the display substrate 1 side of the pixel B. That is, the particle amount of the cyan particle group 11C included in the pixel A while maintaining the magnitude relationship of the particle amount of the cyan particle group 11C included in the pixel A> the particle amount of the cyan particle group 11C included in the pixel B. Is larger than the particle amount of the cyan particle group 11C included in the pixel A when the process of step S320 is completed.

  Next, in step S360, it is determined whether or not the voltage −V1c is applied to the pixel electrode 4B over the number of shift frames. If the determination is negative, the process of this step is repeated until the voltage −V1c is applied to the pixel electrode 4B by the number of frames that are shifted. And in affirmation determination, it transfers to step S370.

  In step S370, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A is the voltage −V1c. At this time, the voltage applied to the pixel electrode 4B continues to be the voltage −V1c.

  In step S380, it is determined whether or not the voltage −V1c is applied to the pixel electrode 4A and the pixel electrode 4B over the number of cyan reset frames.

  If the determination is negative, the process in this step is repeated until the voltage −V1c is applied to the pixel electrode 4A and the pixel electrode 4B by the number of cyan reset frames. And in affirmation determination, it transfers to step S390.

  By the processing in this step, as shown in FIG. 24E, the cyan particle group 11C of each pixel is attached to the display substrate 1, and the pixel A displays black and the pixel B displays cyan.

  In step S390, the voltage application unit 30 is controlled so that the voltage applied to the pixel electrode 4A and the pixel electrode 4B is 0V.

  As described above, with the third reset process shown in FIG. 22, the cyan particle group 11 </ b> C attached to the display substrate 1 side of the pixel B is larger in the amount of the cyan particle group 11 </ b> C attached to the display substrate 1 side of the pixel A. More than the amount of particles.

  In step S54 in FIG. 21, the voltage application unit 30 is controlled so that the drive voltage V1c is applied to the pixel electrode 4B. By the processing of this step, as shown in FIG. 24F, the cyan particle group 11C attached to the display substrate 1 side of the pixel B and the display substrate 1 side of the pixel A located closer to the pixel B Part of the cyan color particle group 11 </ b> C adhering to is attracted to the back substrate 2 side of the pixel B.

  However, after the third reset processing voltage shown in FIG. 22 is implemented, the amount of the cyan particle group 11C attached to the display substrate 1 side of the pixel A is the cyan particle group attached to the display substrate 1 side of the pixel B. More than 11C particles. Therefore, by applying the drive voltage V1c to the pixel electrode 4B, the variation in the amount of cyan particles 11C included in the pixel A and the pixel B can be suppressed within a predetermined range, and the display density of the image between the pixels can be reduced. The variation in is suppressed.

  As described above, in this embodiment, even when two types of particle groups 11 charged with different polarities are sealed in the display medium 10, the adjacent pixel groups 11 are displayed according to the display color to be displayed on the display medium 10. By changing the application sequence of the reset voltage applied to each pixel, even if an image displaying a different display color is repeatedly displayed on each adjacent pixel, variation in density between pixels is suppressed.

  Specifically, when displaying a combination other than white and black, for example, red and cyan, in adjacent pixels, processing similar to the reset voltage application processing in the first embodiment is executed. Further, when white and black are displayed by adjacent pixels, processing similar to the reset voltage application processing in the first embodiment is performed before applying the drive voltages in steps S24 and S54.

  Thereby, the amount of particles contained in each of the adjacent pixels is individually adjusted, and an image corresponding to the image information is displayed. Therefore, even when the drive voltage is applied to one of the adjacent pixels, the adjacent pixels are adjacent to each other. The amount of particles contained in each pixel falls within a predetermined range. Therefore, even if an image is repeatedly displayed on the display medium 10, an effect of suppressing variation in density between pixels is expected.

  As in the first embodiment, for the reset voltage application processing in this embodiment, by adjusting at least one of the number of shifted frames and the initial reset voltage according to the display density of the image to be displayed on the pixel. Therefore, an effect of further suppressing variation in density between pixels is expected.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such modifications or improvements are added are also included in the technical scope of the present invention.

  In the first to third embodiments, the case where the reset voltage application process is realized by a software configuration has been described. However, the present invention is not limited to this. For example, the voltage application process is performed by hardware. It is good also as a form implement | achieved by a structure.

  As an example of the form in this case, for example, there is a form in which a functional device that executes the same processing as the control unit 40 is created and used. In this case, higher processing speed is expected compared to the above embodiment.

  In the reset voltage application processing of the first to third embodiments, as an example, the movement of the particle group 11 is adjusted by adjusting the voltage value applied to the pixel electrode 4 based on the threshold characteristic of the particle group 11. Controlled. However, the method for controlling the movement of the particle group 11 is not limited to this. For example, the movement of the particle group 11 may be controlled by adjusting at least one of the voltage value applied to the pixel electrode 4 and the application time. Good.

  Further, it goes without saying that the reset voltage application processing of the first to third embodiments is applied even when the display medium 10 includes three or more types of particle groups.

DESCRIPTION OF SYMBOLS 1 Display substrate, 2 Back substrate, 3 Display side electrode, 4 Pixel electrode, 6 Dispersion medium, 10 Display medium, 11C Cyan color particle, 11K Black particle, 11R Red particle, 12W White particle, 20 Drive apparatus, 30 Voltage application part , 40 control unit (computer), 100 display device

Claims (7)

According to the image, each of the plurality of pixels of the display medium in which the particle group moving between the pair of substrates is encapsulated according to the electric field formed between the pair of substrates having at least one of the light transmitting properties Applying means for applying a voltage;
When displaying the different colors in each of the adjacent pixels, and a control means for applying a timing of initialization voltage to be applied to each of the adjacent pixels to control the application means to be different, a,
The control means is a display medium for controlling the application means so that a deviation in application timing of the initialization voltage applied to each of the adjacent pixels increases as the density of the display color to be displayed increases . Drive device.   The control means is a period from when the initialization voltage is applied to one of the adjacent pixels until the initialization voltage is applied to the other pixel as the density of the display color to be displayed increases. In addition, the application unit is controlled so that the voltage value of the initialization voltage applied to the one pixel is increased.
  The display medium driving device according to claim 1. According to the image, each of the plurality of pixels of the display medium in which the particle group moving between the pair of substrates is encapsulated according to the electric field formed between the pair of substrates having at least one of the light transmitting properties Applying means for applying a voltage;
Control means for controlling the application means so that the application timing of the initialization voltage applied to each of the adjacent pixels is different when displaying different display colors in each of the adjacent pixels;
The control means is a period from when the initialization voltage is applied to one of the adjacent pixels until the initialization voltage is applied to the other pixel as the density of the display color to be displayed increases. In addition, the application unit is controlled so that the voltage value of the initialization voltage applied to the one pixel is increased.
Table示媒body of the drive unit. The particle group is a plurality of types of particle groups having different movement start voltages that move between the pair of substrates,
The said control means controls the said application means so that the application procedure of the said initialization voltage applied to each of the said adjacent pixel differs according to the said display color which should be displayed. The display medium driving device according to claim 1.   A display medium driving program for causing a computer to function as control means constituting the driving device according to any one of claims 1 to 4. A pair of substrates, at least one of which is translucent,
A display medium enclosing a group of particles moving between the pair of substrates in response to an electric field formed between the pair of substrates;
The display medium driving device according to any one of claims 1 to 3,
A display device comprising: A pair of substrates, at least one of which is translucent,
A display medium encapsulating a plurality of types of particle groups having different movement start voltages that move between the pair of substrates in accordance with an electric field formed between the pair of substrates;
A display medium driving device according to claim 4,
A display device comprising: