JP2015175987A - Display medium drive device, display medium drive program and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable suppression of occurrence of a density difference in an adjacent display unit in comparison with a case where a voltage application timing is matched in the adjacent display unit.SOLUTION: A display device 100 comprises a voltage application unit 30 that causes a voltage application timing to be made different in a first display unit and a second display unit to apply a second voltage to each of a plurality of display units owned by a display medium 10 including a display substrate 50, a rear surface substrate 52, and a coloring particle group 62 filled between the substrates so as to move between the substrates according to an electric field formed between the substrates so that the particle having moved to the second display unit adjacent to the first display unit from the first display unit by applying a first voltage at a first voltage application time corresponding to a first display density returns to the first display unit when applying a second voltage at a second voltage application time corresponding to a second display density.

Description

  The present invention relates to a display medium driving apparatus, a display medium driving program, and a display apparatus.

  Patent Document 1 discloses an electrophoretic display including a display-side substrate and a rear-side substrate arranged with a predetermined gap therebetween, and an insulating liquid and a plurality of charged electrophoretic particles arranged in the gap between these substrates. In an electrophoretic display device driving method for performing display based on moving the charged electrophoretic particles by applying an electric field to the device, the electrophoretic display device is disposed in each pixel so as to be close to the insulating liquid. A reset step that includes first to third electrodes, and wherein the driving method attracts the charged electrophoretic particles to the second electrode so that the particles are accumulated in a relatively narrow region in the pixel so that the particles are less visible. A writing step for attracting the accumulated charged electrophoretic particles to the first electrode so that the particles are arranged in a relatively wide area in the pixel so that the particles can be easily seen, and the second electric current. A display holding step for transferring the charged electrophoretic particles remaining in the vicinity of the first electrode to the third electrode and restricting the transfer of the charged electrophoretic particles to the first electrode, and the display after the writing step. An electrophoretic display device comprising: controlling a timing of starting a holding process to control an amount of charged electrophoretic particles arranged in the region of the first electrode and controlling a display gradation of a pixel. A driving method is disclosed.

  Patent Document 2 discloses a display panel having a display screen formed by arranging scan electrodes and information electrodes in a matrix, a first means for driving the scan electrodes, and a second means for driving the information electrodes. A driving method for a display device is disclosed in which when a display image is written on the display panel, driving is performed according to a writing history before writing.

  Patent Document 3 discloses that a pair of substrates at least one of which has translucency and is disposed so as to face each other with a gap, a translucent dispersion medium sealed between the pair of substrates, Disclosed is an image display medium comprising a plurality of types of particle groups that are dispersed in a movable manner and move according to an electric field formed between the substrates, and that have different colors and different detachment forces from the substrate. ing.

JP 2004-219841 A JP 2004-271609 A JP 2007-249188 A

  The present invention relates to a display medium driving apparatus, a display medium driving program, and a display medium driving program capable of suppressing the occurrence of a density difference between adjacent display units as compared with the case where voltage application timings are adjusted in adjacent display units. And a display device.

  In order to achieve the above object, a display medium driving apparatus according to claim 1 is configured to move between a pair of substrates and the substrates in accordance with an electric field formed between the pair of substrates. A first voltage is applied to each of a plurality of display units included in a display medium including a group of particles encapsulated in a first voltage application time according to a first display density When the particles that have moved from the first display unit to the second display unit adjacent to the first display unit applied the second voltage for the second voltage application time corresponding to the second display density. In order to return to the first display section, the first display section and the second display section are provided with voltage application means for applying the second voltage at different voltage application timings.

  According to a second aspect of the present invention, the voltage application unit starts application of the second voltage to the second display unit, and after a time corresponding to the first display density has elapsed, Application of the second voltage to the first display unit is started.

  According to a third aspect of the present invention, the particle group is different in color from the first particle group and the first particle group, and has a voltage threshold value for peeling from the substrate as compared with the first particle group. A low second particle group, and the voltage applying means applies the first voltage at a first voltage application time corresponding to a first display density in the color of the first particle group. The second particle group that has moved from the first display unit to the second display unit adjacent to the first display unit is a second according to the second display density in the color of the second particle group. When the second voltage is applied during the voltage application time, the first display unit and the second display unit have different voltage application timings so as to return to the first display unit. Apply a voltage of.

  A display medium driving program according to a fourth aspect of the invention is a display medium driving program for causing a computer to function as each means constituting the display medium driving device according to any one of claims 1 to 3. It is.

  According to a fifth aspect of the present invention, there is provided a display device comprising: a pair of substrates; and a group of particles sealed between the substrates so as to move between the substrates in response to an electric field formed between the pair of substrates. The display medium and the display medium driving device according to claim 1, which drives the display medium.

  According to the first, fourth, and fifth aspects of the invention, it is possible to suppress the occurrence of a density difference in the adjacent display unit as compared with the case where the voltage application timing is adjusted in the adjacent display unit. Has an effect.

  According to the second aspect of the present invention, the time from the start of application of the second voltage to the second display unit to the start of application of the second voltage to the first display unit is determined. Compared to the case where the display density is set regardless of the first display density, it is possible to prevent the time from being unnecessarily prolonged.

  According to the third aspect of the present invention, the first voltage is applied for the first voltage application time corresponding to the first display density in the color of the first particle group, and the second color in the color of the second particle group. When the second voltage is applied with the second voltage application time corresponding to the display density of 2, the adjacent display unit is compared with the case where the voltage application timing of the second voltage is matched with the adjacent display unit. Thus, it is possible to suppress the occurrence of the density difference.

1 is a schematic configuration diagram of a display device according to a first embodiment. It is a block diagram at the time of comprising a control part with a computer. It is a figure which shows the voltage application characteristic of each migrating particle which concerns on 1st Embodiment. It is a flowchart of the process performed by a control part. It is a figure which shows the flow of the conventional reset drive and display drive. It is a figure which shows the flow of the reset drive and display drive which concern on 1st Embodiment. 3 is a timing chart of voltage application to pixels A and B according to the first embodiment. It is a schematic block diagram of the display apparatus which concerns on 2nd Embodiment. It is a figure which shows the voltage application characteristic of each migrating particle which concerns on 1st Embodiment. It is a figure which shows the flow of the conventional reset drive and display drive. It is a figure which shows the flow of the reset drive and display drive which concern on 2nd Embodiment. It is a timing chart of the voltage application with respect to the pixels A and B which concern on 2nd Embodiment.

  (First embodiment)

  The first embodiment will be described below with reference to the drawings. In order to simplify the description, the present embodiment will be described with reference to a diagram that focuses on one cell as appropriate.

  FIG. 1 schematically shows a display device according to this embodiment. The display device 100 includes a display medium 10 and a drive device 20 that drives the display medium 10. The driving device 20 includes a voltage applying unit 30 that applies a voltage to the display medium 10 and a control unit 40 that controls the voltage applying unit 30 in accordance with image information of an image to be displayed on the display medium 10. Yes.

  In the display medium 10, a translucent display substrate 50 serving as an image display surface and a back substrate 52 serving as a non-display surface are arranged to face each other with a gap. The display substrate 50 has a display-side electrode 54 as a common electrode having translucency, and the back substrate 52 has a plurality of back-side electrodes 56 as pixel electrodes. Although FIG. 1 shows a case where the two back-side electrodes 56A and 56B are formed on the back substrate 52, in the actual display medium 10, a large number of back-side electrodes 56 are formed on the back substrate 52. . Hereinafter, the back side electrodes 56A and 56B may be simply referred to as the back side electrodes 56 when they are not distinguished. Further, the display-side electrode 54 and the back-side electrode 56 may be external electrodes without being provided on the display substrate 50 and the back-side substrate 52.

  Further, the display medium 10 is provided with a gap member 58 that holds the display substrate 50 and the back substrate 52 at a predetermined interval and partitions the substrate into a plurality of cells.

  The cell indicates a region surrounded by the display substrate 50 provided with the display-side electrode 54, the back substrate 52 provided with the plurality of back-side electrodes 56, and the gap member 58. Each electrode surface is provided with surface layers 55 and 57 made of a protective film, an insulating material, or the like. Although FIG. 1 shows the case where two backside electrodes 56A and 56B are included in one cell, the number of backside electrodes 56 included in one cell is limited to two. is not.

  In the cell, a dispersion medium 60 made of, for example, an insulating liquid, and a colored particle group 62 and a white particle group 66 dispersed in the dispersion medium 60 are enclosed.

  The colored particle group 62 has a characteristic that the colored particle group 62 migrates independently by applying a threshold voltage that generates an electric field equal to or higher than a predetermined threshold electric field between the display-side electrode 54 and the back-side electrode 56. Have. On the other hand, as an example, the white particle group 66 is negatively charged with a polarity opposite to that of the colored particle group 62, but the charge amount is smaller than that of the colored particle group 62, and the colored particle group 62 moves to one of the substrate sides. This is a floating particle group that does not move to any electrode side even when a voltage that generates an electric field is applied between the electrodes.

  Instead of using the white particle group 66, white color may be displayed by mixing a colorant in the dispersion medium 60.

  In the present embodiment, the case where the colored particle group 62 is a positively charged electrophoretic particle (red particle R) having a red color is described, but the present invention is not limited to this. In addition, the voltage value of the voltage to be applied in the following description is also an example, and is not limited to this, and may be appropriately set according to the charging polarity, charging amount, particle size, responsiveness, distance between electrodes, and the like of each particle. That's fine. Hereinafter, red particles are referred to as red particles R, and white particles are referred to as white particles W.

  The driving device 20 (the voltage application unit 30 and the control unit 40) causes the colored particle group 62 to migrate by applying a voltage corresponding to the color to be displayed between the substrates of the display medium 10, and according to the respective charging polarities. Then, it is attracted to either the display substrate 50 or the back substrate 52.

  The voltage application unit 30 is electrically connected to the display-side electrode 54 and the back-side electrode 56, respectively. Further, the voltage application unit 30 is connected to the control unit 40 so as to exchange signals.

  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) 40A, a ROM (Read Only Memory) 40B, a RAM (Random Access Memory) 40C, a non-volatile memory 40D, and an input / output interface (I / O) 40E via a bus 40F. A voltage application unit 30 and a communication line I / F (Interface) 32 are connected to the I / O 40E. In this case, a program for causing the computer 40 to execute processing for instructing the voltage application unit 30 to apply a voltage necessary for displaying an image, which will be described later, is written in, for example, the nonvolatile memory 40D, and is read and executed by the CPU 40A. . The program may be provided by a recording medium such as a CD-ROM.

  The voltage application unit 30 is a voltage application device for applying a voltage to the display side electrode 54 and the back side electrode 56, and applies a voltage according to the control of the control unit 40 to the display side electrode 54 and the back side electrode 56. .

  In this embodiment, as an example, the display side electrode 54 is a common electrode formed on the entire surface of the display substrate 50, and each of the plurality of back side electrodes 56 has a pixel configuration corresponding to so-called active matrix driving. Therefore, in the present embodiment, a case will be described in which the display-side electrode 54 as a common electrode is grounded and a voltage corresponding to an image is applied to the plurality of back-side electrodes 56.

  In the present embodiment, one display unit corresponds to one pixel electrode. That is, the display medium has a plurality of display portions corresponding to the number of pixel electrodes. Furthermore, in the present embodiment, a case where one pixel electrode (display unit) corresponds to one pixel will be described. The pixel corresponding to the back side electrode 56A is the pixel A, and the pixel corresponding to the back side electrode 56B is the pixel B. Called. A plurality of pixel electrodes (display units) may correspond to one pixel.

  The communication line I / F 32 is connected to a communication line (not shown) and communicates data with a terminal device such as a server or a personal computer (not shown) connected to the communication line. The communication line (not shown) may be either a wired line or a wireless line. For example, image information of an image to be displayed on the display medium 10 may be acquired from a server or personal computer (not shown).

  FIG. 3 shows the characteristics of the applied voltage necessary to move the positively charged red particles R to the display substrate 50 side and the back substrate 52 side in the display device 100 according to the present embodiment. In FIG. 3, the applied voltage characteristic of the red particle R is represented by a characteristic 50R. FIG. 3 shows the relationship between the voltage applied to the back-side electrode 56 with the display-side electrode 54 as the ground (0 V) and the display density due to the red particles R.

  As shown in FIG. 3, the movement start voltage (threshold voltage) for generating an electric field for starting movement of the red particles R on the back substrate 52 side to the display substrate 50 side is + V1a, and the red particles R on the display substrate 50 side. The movement start voltage for generating an electric field that starts moving toward the back substrate 52 is −V1a. Here, the movement start voltage refers to a voltage for generating an electric field in which a particle group existing on the rear substrate 52 or the display substrate 50 side starts moving toward the opposite substrate. Accordingly, when the voltage of + V1a or higher is applied, the red particles R on the back substrate 52 side move to the display substrate 50 side, and when the voltage of −V1a or lower is applied, the red particles R on the display substrate 50 side are transferred to the back substrate 52. Move to the side. The voltage for generating an electric field in which all the red particles R on the back substrate 52 side move to the display substrate 50 side is + V1, and the electric field for all the red particles R on the display substrate 50 side to move to the back substrate 52 side. The voltage for generating is -V1.

  The amount of red particles R moved from the back substrate 52 side to the display substrate 50 side changes the voltage value of the applied voltage when, for example, the pulse width (voltage application time) of the applied voltage is the same. (Voltage value modulation). For example, when controlling the amount of red particles R moved from the back substrate 52 side to the display substrate 50 side, the pulse width of the applied voltage is made the same, and the voltage value is set to an arbitrary voltage value Vx of + V1a or more. Thus, the red particles R having a particle amount corresponding to the voltage value can be moved to the display substrate 50 side. Thereby, the gradation display of the red particles R is controlled. The same applies to the amount of particles when the red particles R on the display substrate 50 side are moved to the back substrate 52 side.

  The threshold voltage of the particles can be adjusted, for example, by changing the charge amount of the particles by changing the particle material, surface coating material of the particles, additives, particle diameter, particle surface shape, surface area, etc. It is adjusted by controlling the electrostatic force received from the electric field. Alternatively, it is adjusted using electrostatic attraction generated by charging the particle surface material, substrate surface material, van der Waals force, or the like.

In addition, the voltage value of the applied voltage may be the same, and the pulse width, that is, the voltage application time may be changed to control the particle amount of the moving particles to control the gradation display (pulse width modulation). ). For example, when controlling the amount of red particles R to be moved from the back substrate 52 side to the display substrate 50 side, if the voltage value of the applied voltage is a predetermined voltage value Vx of + V1a or more, the pulse width is As the length increases, the amount of red particles R that move toward the display substrate 50 increases. Therefore, the gradation display of the red particles R is controlled by fixing the voltage value and setting the pulse width to a pulse width having a length corresponding to the gradation. In the present embodiment, a case where the amount of moving particles is controlled by pulse width modulation will be described. In the following, for example, the voltage application time corresponding to the display density x (%) is represented by _tdx . The display density x corresponds to the amount of particles moved from one substrate to the other, but all red particles R are transferred from one substrate to the other when the red display density is 100% or 0%. It is the same in that it is moved to the substrate. Therefore, when the adhesion force of the particles is the same between the display substrate 50 and the back substrate 52, the voltage application time is the same regardless of whether the red display density is 100% or 0%. In addition, when the adhesion force of the particles is not the same between the display substrate 50 and the back substrate 52, or when the laminated state of the particles is different in a display medium using a plurality of types of particles, that is, one type of particles adheres to the substrate alone In the case of attaching to a substrate in a state where a plurality of types of particles are laminated, the voltage application time of both is not necessarily the same.

  Next, as an operation of the present embodiment, control executed by the CPU 40A of the control unit 40 will be described with reference to a flowchart shown in FIG.

  First, in step S10, image information of an image to be displayed on the display medium 10 is acquired from an external device (not shown) via the communication line I / F 32, for example.

In step 12, the voltage application unit 30 is instructed to apply the reset voltage. Here, the reset voltage is a voltage for moving all red particles R to the display substrate 50 side as an example. That is, the reset voltage is a positive voltage having a voltage application time t _d100 corresponding to a red display density of 100% and a predetermined voltage value Vx having a voltage value of + V1a or higher. Therefore, as shown in the state 5A of FIG. 5, when the reset voltage, which is a positive voltage, is applied to the backside electrodes 56A and 56B with the voltage application time _td100 , all red particles R move to the display substrate 50 side. And adhere. Thereby, from the display substrate 50 side, the red color due to the red particles R is displayed on both the pixel A corresponding to the back side electrode 56A and the pixel B corresponding to the back side electrode 56B.

  In step S <b> 14, the display drive voltage to be applied to the back side electrode 56 is determined based on the acquired image information, and the voltage application unit 30 is instructed. The voltage application unit 30 applies the display drive voltage instructed by the control unit 40 to the back side electrode 56.

  This display drive voltage is a voltage for causing the display medium 100 to display an image corresponding to the acquired image information. That is, a voltage for a voltage application time corresponding to the red gradation (display density) to be displayed is applied to the pixel to display red.

For example, when displaying red with a display density of 50% on the pixel A and displaying red with a display density of 0% (first display density), that is, white on the pixel B, the voltage application time for the pixel A is the display substrate. A voltage application time t _d50 for moving half of the 50-side red particles R to the back substrate 52 side and a negative voltage of a predetermined voltage value −Vx having a voltage value less than −V1a are applied. On the other hand, in the pixel B, the voltage application time is a voltage application time t _d0 (> t _d50 ) for moving all the red particles R on the display substrate 50 side to the back substrate 52 side, and the negative voltage value is −Vx. A voltage (first voltage) is applied.

  Thereby, as shown in the state 5B of FIG. 5, when a voltage is applied to the pixels A and B, the red particles R start to move toward the back substrate 52, and as shown in the state 5C of FIG. When half of the red particles R on the display substrate 50 side move to the back substrate 52 side, the voltage application to the pixel A is stopped. On the other hand, for the pixel B, after the voltage application for the pixel A is stopped, the voltage application is continued until all the red particles R on the display substrate 50 side move to the rear substrate 52 side. For this reason, as shown in the state 5C in FIG. 5, among the red particles R of the pixel A attached to the display substrate 50 side, some of the red particles R close to the pixel B move to the pixel B side. . Here, in order to display red with a display density of 100% again on the pixels A and B, the same positive voltage (second voltage) as in the state 5A is applied to the pixels A and B as shown in the state 5D in FIG. Then, as shown in the state 5E of FIG. 5, all the red particles R on the back side electrodes 56A and 56B move to the display substrate 50 side. At this time, since the red particles R are biased toward the pixel B, a density difference occurs between the pixels A and B.

  Therefore, in this embodiment, the voltage application timing is different between the pixel A and the pixel B so that the red particles R that have moved from the pixel A to the pixel B return to the pixel A when the second voltage is applied. A second voltage is applied. Specifically, the application of the second voltage to the pixel A is started after the time corresponding to the first display density has elapsed after the application of the second voltage to the pixel B is started. .

  FIG. 6 shows a driving flow when the second voltage is applied to the pixel A and the pixel B at different voltage application timings. FIG. 7 shows a timing chart of voltage application of the pixels A and B. States 6A to 6C in FIG. 6 are the same as states 5A to 5C in FIG.

As shown in FIG. 7, the reset voltage is applied to the pixels A and B during the period from t1 to t2 (voltage application time _td100 ) (state 6A in FIG. 6). Next, a negative voltage is applied to the pixel A in the period of t2 to t3 (voltage application time _{t d50)} (the state of FIG. 6 6B), a negative voltage to the pixel B in the period of t2 to t4 (voltage application time _{t d0)} Is applied (states 6B and 6C in FIG. 6). Next, a positive voltage is applied to the pixel B in the period t4-t6 (voltage application time _{t d100)} (the state of FIG. 6 6D, 6E), the pixel A in the period t5 to t7 (voltage application time _{t d100)} A positive voltage is applied (state 6E in FIG. 6).

  In the present embodiment, the second voltage is not applied to the pixels A and B at the same time as shown in the state 5D of FIG. 5, but only to the pixel B as shown in the state 6D of FIG. Is applied (at time t4 in FIG. 7), and after the time corresponding to the first display density has elapsed, the second voltage is also applied to the pixel A as shown in the state 6E in FIG. Is started (time t5 in FIG. 7). Here, the time corresponding to the first display density (tx = t5-t4 in FIG. 7) is moved from the display substrate 50 side of the pixel B to the rear substrate 52 side as shown in the state 6C of FIG. This time corresponds to the amount of red particles R. In the example of FIG. 6, the time corresponds to the amount of all red particles R in the pixel B. Therefore, for example, if the amount of red particles R to be moved is half the amount of particles (display density 50%), the application of the second voltage to the pixel B is started for a time corresponding to the first display density. The time from the start of applying the second voltage to the pixel A is half that of the case where the amount of red particles R to be moved is all the amount of particles (display density 0%).

  Thus, in the present embodiment, the second voltage is applied to the pixel B so that the red particles R that have moved from the pixel A to the pixel B return to the pixel A when the second voltage is applied. Since the application of the second voltage to the pixel A is started after the time corresponding to the first display density has elapsed since the start, the occurrence of a density difference between the pixel A and the pixel B is suppressed. Is done.

  (Second Embodiment)

  Next, a second embodiment will be described. In the second embodiment, a case where there are two types of colored particles will be described.

  Further, red particles are denoted as red particles R, cyan particles having a complementary color relationship with red are denoted as cyan particles C, and white particles are denoted as white particles W. Each particle and its particle group are indicated by the same symbol (symbol). .

  FIG. 8 schematically shows a display device according to the present embodiment. The display device 100A is different from the display device 100 in FIG. 1 in that the colored particle group 63 is provided on the display medium 10A, and the rest is the same as the display device 100, and detailed description thereof is omitted.

  In the present embodiment, a case where the colored particle group 63 is positively charged electrophoretic particles (cyan particles C) having a cyan color will be described.

  FIG. 9 shows voltages applied to move positively charged cyan particles C and positively charged red particles R to the display substrate 50 side and the back substrate 52 side in the display device 100A according to the present embodiment. The display density characteristics (voltage-display density characteristics) are shown. In FIG. 9, the voltage-display density characteristic of the cyan particle C is represented by a characteristic 50C, and the voltage-display density characteristic of the red particle R is represented by a characteristic 50R. 3 is different from the display density characteristic of FIG. 3 in that a characteristic 50C is added, and the others are the same as those in FIG.

  As shown in FIG. 9, the threshold voltage for generating an electric field at which the cyan particles C on the back substrate 52 side start moving toward the display substrate 50 side is + V2a, and the cyan particles C on the display substrate 50 side are on the back substrate 52 side. The threshold voltage for generating an electric field that starts moving to -V2a. Therefore, by applying a voltage of + V2a or higher, the cyan particles C on the back substrate 52 side move to the display substrate 50 side, and by applying a voltage of −V2a or lower, the cyan particles C on the display substrate 50 side are transferred to the back substrate 52. Move to the side. The voltage for generating an electric field in which all the cyan particles C on the back substrate 52 side move to the display substrate 50 side is + V2, and the electric field for all the cyan particles C on the display substrate 50 side to move to the back substrate 52 side. The voltage to generate is -V2.

  The amount of cyan particles C moved from the back substrate 52 side to the display substrate 50 side changes the voltage value of the applied voltage, for example, when the pulse width (voltage application time) of the applied voltage is the same. (Voltage value modulation). For example, when the amount of cyan particles C moved from the back substrate 52 side to the display substrate 50 side is controlled, the pulse width of the applied voltage is the same, and the voltage value is set to an arbitrary voltage value Vy of + V2a or more. The cyan particles C having a particle amount corresponding to the voltage value are moved to the display substrate 50 side. Thereby, the gradation display of the cyan particles C is controlled. The same applies to the amount of particles when the cyan particles C on the display substrate 50 side are moved to the back substrate 52 side.

  In addition, the voltage value of the applied voltage may be the same, and the pulse width, that is, the voltage application time may be changed to control the particle amount of the moving particles to control the gradation display (pulse width modulation). ). For example, in the case of controlling the amount of cyan particles C moved from the back substrate 52 side to the display substrate 50 side, when the voltage value of the applied voltage is a predetermined voltage value Vy of + V2a or more, the pulse width is As the length increases, the amount of cyan particles C that move toward the display substrate 50 increases. Therefore, the gradation display of the red particles R is controlled by fixing the voltage value and setting the pulse width to a pulse width having a length corresponding to the gradation. In the present embodiment, as in the first embodiment, a case will be described in which the amount of moving particles is controlled by pulse width modulation.

  When displaying an image on such a display medium 10, the image is displayed by driving sequentially from the particles with the higher threshold voltage. That is, after the cyan particles C are driven to set the cyan color to a desired gradation value, the red particles R are driven to set the red to the desired gradation value, thereby displaying an image.

  Control executed by the CPU 40A of the control unit 40 is the same as in the first embodiment. That is, control according to the flowchart shown in FIG. 4 is performed.

  First, in step S10, image information of an image to be displayed on the display medium 10 is acquired from an external device (not shown) via the communication line I / F 32, for example.

In step 12, the voltage application unit 30 is instructed to apply the reset voltage. Here, the reset voltage is a voltage for moving all cyan particles C and red particles R to the display substrate 50 side as an example. That is, the reset voltage is a positive voltage having a voltage application time t _d100 corresponding to a display density of 100% for cyan and red, and a predetermined voltage value Vy having a voltage value of + V2a or higher. For this reason, as shown in the state 10a of FIG. 10, when the reset voltage, which is a positive voltage, is applied to the backside electrodes 56A and 56B during the voltage application time _td100 , all the cyan particles C and red are applied to the display substrate 50 side. Particles R move and adhere. As a result, from the display substrate 50 side, black due to the cyan particles C and red particles R is displayed on both the pixel A corresponding to the back electrode 56A and the pixel B corresponding to the back electrode 56B.

  In step S <b> 14, the display drive voltage to be applied to the back side electrode 56 is determined based on the acquired image information, and the voltage application unit 30 is instructed. The voltage application unit 30 applies the display drive voltage instructed by the control unit 40 to the back side electrode 56.

For example, when displaying a mixed color of cyan and red 50% with a display density of 100% (first display density) on the pixel A and displaying red with a display density of 50% on the pixel B, first, the pixels A and B are The voltage application time t _d0 for moving all the red particles R on the display substrate 50 side to the rear substrate 52 side, the voltage value being a predetermined voltage value less than −V1a and greater than −V2a− A negative voltage of Vy2 is applied. Thereby, as shown in the state 10b of FIG. 10, when a voltage is applied to the pixels A and B, all the red particles R move to the back substrate 52 side.

Next, as shown in the state 10c of FIG. 10, the voltage application time is a voltage application time t _d0 for moving all the cyan particles C on the display substrate 50 side to the back substrate 52 side, and the voltage value is −V2a. A negative voltage (first voltage) of a predetermined voltage value −Vy of less than is applied. As a result, as shown in the state 10c of FIG. 10, all the cyan particles C of the pixel B move to the back substrate 52 side. However, since a potential difference is generated between the back side electrodes 56A and 56B, the back side electrode 56A. The upper part of the red particles R moves to the back electrode 56B side. Here, in order to move the red particles R having a particle amount corresponding to a display density of 50% to the display substrate 50 side of the pixels A and B, as shown in a state 10d of FIG. Voltage application time t _d50 for moving half of the red particles R on the side to the display substrate 50 side, a positive voltage (second voltage) of a predetermined voltage value + Vy2 that is + V1a or more and less than + V2a When applied to the pixels A and B, as shown in the states 10e and 10f of FIG. 10, half of the red particles R on the back side electrodes 56A and 56B move to the display substrate 50 side. At this time, since the red particles R are biased toward the pixel B, a density difference occurs between the pixels A and B.

  Therefore, in the present embodiment, the pixel A and the pixel B so that the red particle R that has moved from the pixel A to the pixel B during display driving of the cyan particle C returns to the pixel B when the second voltage is applied. The second voltage is applied at different voltage application timings. Specifically, the application of the second voltage to the pixel A is started after the time corresponding to the first display density has elapsed after the application of the second voltage to the pixel B is started. .

  FIG. 11 shows a driving flow when the second voltage is applied to the pixel A and the pixel B at different voltage application timings. FIG. 12 shows a timing chart of voltage application of the pixels A and B. States 11a to 11c in FIG. 11 are the same as states 10a to 10c in FIG.

As shown in FIG. 12, a reset voltage is applied to the pixels A and B during the period from t1 to t2 (voltage application time _td100 ) (state 11a in FIG. 11). Next, a negative voltage is applied to the pixels A and B during the period t2 to t3 (voltage application time _td0 ) (state 11b in FIG. 11), and the pixel B is applied to the pixel B during the period t3 to t4 (voltage application time _td0 ). A negative voltage is applied (state 11c in FIG. 11). Next, a positive voltage is applied to the pixel B in the period t4-t6 (voltage application time _{t d50)} (the state of FIG. 11 11d~11f), the pixel A in the period t5 to t7 (voltage application time _{t d50)} A positive voltage is applied (states 11e and 11f in FIG. 11).

  In the present embodiment, as shown in the state 11d of FIG. 11, the second voltage is not applied to the pixels A and B at the same time, but the second voltage is applied only to the pixel B (t4 in FIG. 12). After the time corresponding to the first display density has elapsed, as shown in the state 11e of FIG. 11, the application of the second voltage to the pixel A is started (at the time t5 in FIG. 12). ). Here, the time corresponding to the first display density (tx = t5−t4 in FIG. 12) is moved from the display substrate 50 side of the pixel B to the back substrate 52 side as shown in the state 11c of FIG. This time corresponds to the amount of cyan particles C. In the example of FIG. 11, the time corresponds to the amount of all cyan particles C in the pixel B. Therefore, for example, if the amount of cyan particles C to be moved is half the amount of particles (display density 50%), the application of the second voltage to the pixel B is started for a time corresponding to the first display density. The time from the start of applying the second voltage to the pixel A is half that of the case where the amount of cyan particles C to be moved is all the amount of particles (display density 0%).

  As described above, in the present embodiment, the red particles R moved from the pixel A to the pixel B by the display driving of the cyan particles C are returned to the pixel A when the second voltage is applied to the pixel B. After the application of the second voltage is started, the application of the second voltage to the pixel A is started after the time corresponding to the first display density has elapsed. As a result, the occurrence of a density difference between the pixel A and the pixel B is suppressed.

  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.

10, 10A Display medium 20 Drive device 30 Voltage application unit 40 Control unit 50 Display substrate 52 Back substrate 54 Display side electrodes 56A, 56B Back side electrode 58 Gap member 60 Dispersion medium 62, 63 Colored particle group 66 White particle group 100, 100A Display device

Claims (5)

Each of a plurality of display units included in a display medium including a pair of substrates and a group of particles sealed between the substrates so as to move between the substrates in accordance with an electric field formed between the pair of substrates. On the other hand, the first voltage is applied for the first voltage application time corresponding to the first display density, so that the first display unit moves to the second display unit adjacent to the first display unit. The first display unit and the second display unit are configured to return to the first display unit when the second voltage is applied with a second voltage application time corresponding to the second display concentration. A display medium driving device comprising: a voltage applying unit configured to apply the second voltage at different voltage application timings with respect to the display unit. The voltage application means applies the second display unit to the first display unit after a time corresponding to the first display density has elapsed since the start of application of the second voltage to the second display unit. The display medium driving device according to claim 1, wherein application of the second voltage is started. The particle group is a first particle group, a second particle group that is different in color from the first particle group and has a lower threshold voltage than the first particle group for peeling from the substrate, Including
The voltage application means applies the first voltage at a first voltage application time corresponding to the first display density in the color of the first particle group, thereby causing the first display to display the first display. The second particle group that has moved to the second display unit adjacent to the unit applies a second voltage for a second voltage application time corresponding to a second display density in the color of the second particle group. The second voltage is applied at different voltage application timings in the first display unit and the second display unit so that the first display unit returns to the first display unit. 3. A display medium driving apparatus according to 2.   A display medium driving program for causing a computer to function as each unit constituting the display medium driving device according to claim 1. A display medium comprising: a pair of substrates; and a particle group enclosed between the substrates so as to move between the substrates in accordance with an electric field formed between the pair of substrates;
The display medium driving device according to any one of claims 1 to 3, which drives the display medium;
A display device comprising: