JP2013250384A - Drive device of display medium, drive program of the display medium and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive device of display medium, a drive program of the display medium and a display device capable of uniformizing a group of particles without allowing a viewer to visually recognize unlike the case a voltage is applied across substrates for uniformizing the group of particles.SOLUTION: On a display medium 10 which has: a pair of substrates including a display substrate 50 and a back substrate 52 disposed opposite to the display substrate 50 being interposed by a gap; and a group of colored particles 62 sealed between substrates of a display side electrode 54 formed at the display substrate 50 side and plural back side electrodes 56 formed at the back substrate 52 side so as to move between the substrates according to an electric field formed between the pair of substrates, a drive device 20 applies a first voltage, which is a voltage of a threshold value voltage or less for generating an electric field for separating the group of colored particles 62 from a substrate in the pair of substrates as well as a voltage larger than a voltage for generating an electric field that separates the group of colored particles 62 from one back side electrode 56 between the neighboring back side electrodes 56, to at least one of the neighboring back side electrodes 56.

Description

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

  Patent Document 1 discloses an electrophoresis including a first electrode, a second electrode facing the first electrode, and charged electrophoretic particles sandwiched between the first electrode and the second electrode. And a pixel switching element connected to a scanning line and a data line, a memory circuit connected to the pixel switching element, and the memory A switch circuit provided between the circuit and the first electrode, a pixel driver connected to the pixel switching element via the scan line and the data line, a first control line, A potential control unit connected to the switch circuit via a second control line, and connected to the second electrode via a third control line, the first control line from the potential control unit Supplying a first potential to the control line; A first period in which a second potential is supplied to the second control line, the second potential is supplied from the potential control unit to the first control line, and the first control line is supplied with the first potential. An electrophoretic display device is disclosed in which a preparatory period including a second period for supplying the potential is provided before a period for displaying an image.

JP 2008-249794 A

  An object of the present invention is to provide a display medium drive device, a drive program, and a display device that can make a particle group uniform without being visually recognized by an observer.

A display medium driving device according to a first aspect of the present invention includes a display substrate, a pair of substrates having a back substrate disposed opposite to the display substrate with a gap, a display-side electrode provided on the display substrate side, At least one kind sealed between the pair of substrates so as to move between the pair of substrates in response to an electric field formed between the plurality of back side electrodes provided on the back substrate side and the pair of substrates. A display medium having a particle group of
The particle group is a voltage equal to or lower than a threshold voltage for generating an electric field for separating the particle group from any one of the pair of substrates, and the particle group is disposed on one back side between the adjacent back side electrodes. Application means for applying a first voltage, which is equal to or higher than a voltage for generating an electric field for peeling from the electrode, to at least one of the adjacent back side electrodes is provided.

  According to a second aspect of the present invention, before the first voltage is applied, the applying means has a voltage value that is equal to or higher than the threshold voltage and is lower than the voltage for displaying an image or the application time is shorter. A second voltage is applied between the substrates.

  In the invention of claim 3, after the application of the second voltage, the application means pulls back the particle group having a polarity opposite to that of the second voltage and separated from the back substrate to the back substrate. A pullback voltage is applied.

  According to a fourth aspect of the present invention, the applying means applies the first voltage to at least one of the adjacent back side electrodes according to a predetermined pattern.

  According to a fifth aspect of the invention, the predetermined pattern is a checkered pattern or a linear pattern.

  According to a sixth aspect of the present invention, the applying means applies the first voltage to at least one of the adjacent back side electrodes according to a display history.

  According to a seventh aspect of the present invention, the applying means applies the first voltage to at least one of the adjacent back-side electrodes according to the image displayed immediately before.

  According to an eighth aspect of the present invention, the particle groups are a plurality of types of particle groups having different colors and threshold voltages for generating an electric field for peeling from the substrate.

  According to a ninth aspect of the present invention, the display medium includes a dispersion medium that is sealed between the pair of substrates and has a color different from that of the particle group.

  According to a tenth aspect of the present invention, a display medium driving program causes a computer to function as an application unit constituting the display medium driving device according to any one of the first to ninth aspects.

  A display device according to an eleventh aspect of the present invention is a display device, a pair of substrates having a display substrate and a back substrate disposed to face the display substrate with a gap, a display-side electrode provided on the display substrate side, and the back substrate A plurality of backside electrodes provided on the side and at least one kind of particles sealed between the pair of substrates so as to 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 9.

  According to the first, tenth, and eleventh aspects of the invention, it is possible to make the particle group uniform without being visually recognized by an observer, compared to the case where a voltage for making the particle group uniform is applied between the substrates. Has the effect.

  According to the second aspect of the present invention, it is possible to shorten the time required for equalization as compared with the case where only the first voltage is applied.

  According to the invention of claim 3, the particles separated from the back substrate side after applying the second voltage were separated from the back substrate as compared with the case where no pullback voltage for pulling back the particle group to the back substrate side was applied. This has the effect that the movement of the particle group to the display substrate side can be suppressed.

  According to the fourth and fifth aspects of the present invention, the particle group can be made more uniform as compared with the case where the first voltage is applied at random.

  According to the sixth aspect of the present invention, the particle group can be made more uniform as compared with the case where the first voltage is applied regardless of the display history.

  According to the seventh aspect of the present invention, the particle group can be made more uniform as compared with the case where the first voltage is applied regardless of the image displayed immediately before.

  According to the eighth aspect of the present invention, there is an effect that multicolor display can be performed as compared with the case of one kind of particle group.

  According to the ninth aspect of the present invention, there is an effect that the mobility of particles can be improved as compared with the case where the space between the display substrate and the back substrate is made a space.

(A) is a schematic block diagram of a display apparatus, (B) 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 an electrophoretic particle. It is a flowchart of the process performed by a control part. It is the schematic which shows the behavior of the electrophoretic particle according to a voltage application. It is a figure for demonstrating the case where a 1st voltage is applied to a checkered pattern shape. It is a figure for demonstrating the case where a 1st voltage is applied linearly. It is a figure which shows the voltage application characteristic of an electrophoretic particle. It is a top view of an address electrode. It is the schematic which shows the behavior of the electrophoretic particle according to a voltage application. It is a figure for demonstrating the case where a 1st voltage is applied linearly. It is a figure for demonstrating the case where a 1st voltage is applied linearly. It is a figure which shows the voltage application characteristic of an electrophoretic particle. It is a figure which shows the voltage application characteristic of an electrophoretic particle.

  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.

  Red particles are denoted as red particles R, and white particles are denoted as white particles W. Each particle and its particle group are indicated by the same symbol (symbol).

  FIG. 1A 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. A display-side electrode 54 having translucency is formed on the display substrate 50, and a back-side electrode 56 is formed on the back substrate 52. 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 back-side electrode 56, and the gap member 58. 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 64 dispersed in the dispersion medium 60 are enclosed. Note that the cells enclosing these particle groups and the dispersion medium 60 are not limited to this shape as long as they do not cause unevenness in the display surface of the particles. For example, the cells may be encapsulated in microcapsules. Absent.

  The colored particle group 62 has a characteristic of migrating by applying a threshold voltage between the display-side electrode 54 and the back-side electrode 56 that generates an electric field equal to or higher than a predetermined threshold electric field for separation from the substrate. Yes. On the other hand, the white particle group 64 has a smaller amount of charge than the colored particle group 62, and even if a voltage that generates an electric field for moving the colored particle group 62 to one of the electrodes is applied between the electrodes, It is a suspended particle group that does not move to the side.

  Instead of using the white particle group 64, white color may be displayed by mixing a colorant in the dispersion medium 60. Alternatively, a white member through which the colored particle group 62 can pass may be used, and this white member encloses a large number of white particles having a particle diameter sufficiently larger than the particle diameter of the colored particle group 62. May be.

  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. What is necessary is just to set suitably the color and particle size of each particle | grain. The voltage value of the voltage applied in the following description is also an example, and is not limited to this, and may be set as appropriate according to the charging polarity, particle size, responsiveness, distance between electrodes, and the like of each particle.

  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 display side electrode 54 and the back side electrode 56 of the display medium 10. 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.

  As shown in FIG. 1B, the control unit 40 is configured as a computer 40, for example. 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. The voltage application unit 30 is connected to the I / O 40E. In this case, a program for causing the computer 40 to execute a process for instructing the voltage application unit 30 to apply a voltage necessary for displaying each color, which will be described later, is written in, for example, the nonvolatile memory 40D, and this 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 the present embodiment, as an example, the display-side electrode 54 is a common electrode formed on the entire surface of the display substrate 50, and the back-side electrode 56 is composed of a plurality of isolated electrodes, and has an electrode configuration corresponding to 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 a plurality of isolated electrodes constituting the back-side electrode 56.

  FIG. 2 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. 2, the applied voltage characteristic of the red particle R is represented by a characteristic 50R. FIG. 2 shows the relationship between the voltage applied to the back-side electrode 56 with the display-side electrode 54 as ground (0 V) and the display density due to the red particles R.

  As shown in FIG. 2, 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, for example, when 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 to be moved from the back substrate 52 side to the display substrate 50 side, the pulse width of the applied voltage is the same, and the voltage value is set to an arbitrary voltage value of + V1a or more. The red particles R having a particle amount corresponding to the voltage value are 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 can be adjusted by controlling the electrostatic force received from the electric field. Alternatively, it can be 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 particle amount of the moving particles may be controlled by changing the pulse width 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 of + V1a or more, the pulse width is long. As the amount of particles increases, the amount of red particles R moving to 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 an example, a case will be described in which the amount of moving particles is controlled by voltage value modulation.

  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, for example, the I / O 40E.

  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 the red particles R to the back substrate 52 side. That is, the reset voltage is a voltage (voltage with a high absolute value of voltage value) lower than the voltage −V1 for moving all the red particles R to the back substrate 52 side. For this reason, when a reset voltage is applied to the back side electrode 56, all the red particles R move and adhere to the back substrate 52 side. Thereby, the white color by the white particle group 64 is displayed from the display substrate 50 side.

  In step S <b> 14, the image writing voltage to be applied to the back side electrode 4 is determined based on the acquired image information, and the voltage application unit 30 is instructed. The voltage application unit 30 applies the image writing voltage instructed by the control unit 40 to the back side electrode 4.

  The image writing voltage is a voltage for causing the display medium 100 to display an image corresponding to the acquired image information. That is, a voltage having a voltage value higher than + V1a that is the movement start voltage of the red particles R and corresponding to the gradation (density) of red to be displayed is applied to the pixel that should display red. Further, no voltage is applied to the pixel that should display white (0 V). Note that the voltage values are the same, and gradation control may be performed by the pulse width.

  In step S16, it is determined whether or not a predetermined time has elapsed. If the predetermined time has elapsed, the process proceeds to step S18. If the predetermined time has not elapsed, the process proceeds to step S20.

  In step S <b> 18, a first voltage for making the red particles R on the back substrate 52 side uniform is applied between the adjacent back side electrodes 56. As image writing is repeated on the display medium 10, the arrangement of particles becomes non-uniform even when the display is reset. This is because, for example, when no image writing voltage is applied to the backside electrode 56 adjacent to the backside electrode 56 to which the image writing voltage is applied, a potential difference is generated between the adjacent backside electrodes 56, so that the image writing is performed. This is because not all the red particles R on the back-side electrode 56 to which the voltage is applied move to the display substrate 50 side, but some of the red particles R move to the adjacent back-side electrode 56 side. Therefore, in the present embodiment, in order to make the red particles R uniform, the first voltage is applied between the adjacent back side electrodes 56.

As shown in FIG. 4, when the distance between the display-side electrode 54 and the back-side electrode 56 is D, the red particles R attached to the display substrate 50 side or the back substrate 52 side are peeled off and moved to the display substrate 50 side. The threshold voltage V1a necessary for the above is expressed by the following equation, where Eth is the electric field strength necessary for peeling from the substrate.
V1a = Eth × D (1)

  Here, as shown in FIG. 4, when a voltage Vs equal to or higher than the threshold voltage V1a is applied to the back side electrode 56B, the red particles R on the back side electrode 56 move in the direction of arrow A and adhere to the display side electrode 54. .

As shown in FIG. 4, when the distance between the adjacent backside electrodes 56 is d (<D), the red particles R attached to the backside electrodes 56 are peeled off and moved to the display substrate 50 side. In order to move to the adjacent back side electrode 56 without making it, it is necessary to apply a voltage Vs that satisfies the following equation.
Eth × d ≦ Vs <Eth × D (2)

By substituting the above equation (1) into the above equation (2), the above equation (2) is expressed by the following equation.
V1a × d / D ≦ Vs <V1a (3)

  For example, when the voltage Vs satisfying the above expression (3) is applied to the back side electrode 56B for a predetermined time and the back side electrode 56A is set to 0 V, the red particles R arranged on the left side of the back side electrode 56B And adheres to the back side electrode 56A. In addition, when the voltage Vs is applied to the back side electrode 56B for a predetermined time and the back side electrode 56C is set to 0 V, the red particles R arranged on the right side of the back side electrode 56B move in the direction of the arrow C, It adheres to the electrode 56C. In this case, since the red particles R move between the adjacent back side electrodes 56, it is possible to suppress the movement of the red particles R from the display substrate 50 side. The voltage Vs is preferably applied several times alternately between the adjacent backside electrodes 56. Thereby, the red particles R on the back side electrode 56 side are agitated and made more uniform. The application time of the voltage Vs is preferably as short as possible, and it is preferable that the application of the first voltage to the entire display medium 10 is completed within, for example, 1 second.

  Further, before applying the first voltage, a voltage equal to or higher than the voltage Vs (second voltage) may be applied with a pulse width shorter than usual. In this case, the length t of the pulse width is set to a length satisfying t <th, where th is the time required for the red particles R peeled from the back substrate 52 side to reach the display-side electrode 54. In this way, by applying the second voltage equal to or higher than the voltage Vs in a short pulse, the red particles R can be easily separated from the back-side electrode 56.

  Further, in this case, after applying a second voltage equal to or higher than the voltage Vs, a pull-back voltage for pulling the red particles R separated from the back-side electrode 56 back to the back-side electrode 56 side, that is, a polarity opposite to the second voltage You may make it apply the voltage of. As a result, the red particles R peeled off from the back-side electrode 56 are prevented from moving and adhering to the display-side electrode 54 and being visually recognized by the observer. In addition, if the particle | grains which move to the display side electrode 54 side are 1/10 or less of all the particles, More preferably, it will be hardly visually recognized by an observer. Therefore, within this range, some red particles R are allowed to move to the display side electrode 54 side.

  Further, the first voltage may be applied according to a predetermined pattern. For example, as a pattern that alternately applies the first voltage in a plurality of predetermined patterns, there is a pattern that is applied in a checkered pattern as shown in FIG. In the figure, as an example, a case where one cell is configured by 4 × 4 pixels by the gap member 58 is shown. In this case, the voltage Vs is applied to the hatched pixel back-side electrode 56D in FIG. 5A for a predetermined time, and the other back-side electrode 56E is set to 0 V with no voltage applied. Next, as shown in FIG. 5B, the voltage Vs is applied in a pattern that is an inversion of FIG. That is, no voltage is applied to the back-side electrode 56D to which the voltage Vs is applied in FIG. 9A, and the voltage Vs is applied to the back-side electrode 56E to which no voltage is applied in FIG. To do. By repeating this alternately a predetermined number of times, the red particles R on the back side electrode 56 side are stirred and made uniform. It is to be noted that a voltage having a reverse polarity for pulling the red particles R back to the back side electrode 56 side is sometimes applied so that the red particles R do not move to the display side electrode 54 side while the first voltage is alternately applied. You may make it do.

  Further, as a pattern for applying the first voltage while gradually shifting a predetermined pattern in a predetermined direction, there is a pattern applied in a linear pattern. For example, as shown in FIG. 6, the voltage Vs is applied to the back-side electrode 56F for one line, and the back-side electrodes 56 of other lines are set to 0V. Then, the line to which the voltage Vs is applied is sequentially changed. As a result, the red particles R on the back side electrode 56 side are agitated and made uniform.

  Further, the first voltage may be applied according to the display history of the image displayed on the display medium 10. For example, when the same image is repeatedly displayed, the particles are likely to be biased, and in such a case, the number of times of applying the first voltage is increased as the number of times the same image is displayed increases. It may be.

  Further, the first voltage may be applied according to the image displayed immediately before. For example, the first voltage may be applied only between the back-side electrode 56 corresponding to the pixel that has moved the red particles R toward the display substrate 50 and the back-side electrode 56 adjacent thereto.

  In step S20, it is determined whether or not image rewriting has been instructed from an external device. If image rewriting has been instructed, the process returns to step S10 to execute the same processing as described above. On the other hand, if the instruction to rewrite the image is not given, the process proceeds to step S22. In step S22, it is determined whether or not the end of the image display is instructed from the external device. If the end is not instructed, the process returns to step S16 to execute the same processing as described above, and the end is instructed. Terminates this routine.

  Thus, in this embodiment, since the 1st voltage for making a particle uniform is applied between the adjacent back side electrodes 56, a particle group is made uniform, without being visually recognized by an observer.

  In the present embodiment, the case where the first voltage is applied every time a fixed time elapses has been described. However, the timing for applying the first voltage is not limited thereto. For example, the first voltage may be applied while switching images, such as immediately before rewriting an image or immediately after rewriting an image. Alternatively, the first voltage may be applied every time image rewriting is performed a predetermined number of times. Alternatively, the first voltage may be applied before the first image is displayed after the display device 100 is turned on or immediately before the power is turned off. When the power saving mode is provided, the first voltage may be applied during the power saving mode. Furthermore, the first voltage may be applied in a short time when switching images, and the first voltage may be applied for a longer time than when switching images when a predetermined time elapses.

  Moreover, although this embodiment demonstrated the case where there was one kind of colored particle, you may use several types of particle group from which a color and threshold voltage differ. In this case, the plurality of types of particle groups may be charged with the same polarity or may be charged with opposite polarities. FIG. 7 shows, as an example, characteristics of applied voltages necessary 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 FIG. 7, the applied voltage characteristic of cyan particles C is represented by characteristic 50C, and the applied voltage characteristic of red particles R is represented by characteristic 50R. FIG. 7 shows the relationship between the voltage applied to the back-side electrode 56 with the display-side electrode 54 as ground (0 V) and the display density of each particle group. The characteristic 50R of the red particle R is the same as that shown in FIG.

  As shown in FIG. 7, the movement start voltage (threshold voltage) for generating an electric field for starting the movement of the cyan particles C on the back substrate 52 side to the display substrate 50 side is + V2a, and the cyan particles C on the display substrate 50 side. The movement start voltage for generating an electric field that starts moving toward the back substrate 52 is −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. As shown in FIG. 2, | V1a | <| V2a |, and the absolute value of the voltage value of the threshold voltage of the cyan particle C is larger than the absolute value of the threshold value of the red particle R.

In such a case, a first voltage Vs that satisfies the following formula is applied.
V2a × d / D ≦ Vs <V1a (3)

  Further, a particle group of three or more colors (for example, cyan, magenta, yellow, etc.) may be used.

  When a plurality of types of particle groups are used, all may have the same particle diameter, and at least two types of particle groups may have different particle diameters.

  In this embodiment, the case where the display medium having a configuration in which the dispersion medium is sealed between the substrates is described, but a display medium in which the space between the substrates is a space (gas) may be used.

  Note that the configuration of the display device 100 described in this embodiment (see FIG. 1) is merely an example, and unnecessary portions may be deleted or new portions may be added without departing from the scope of the present invention. Needless to say.

  Examples will be described below.

Example 1
As an electrophoretic solution, about 25% by mass of uncharged white particles with a center particle size of about 0.5 μm and about 1% by mass of positively charged black particles with a center particle size of about 1 μm are used as silicone oil (Shin-Etsu Silicone, KF- 96L-2cs) was used. Each particle has the same specific gravity as that of silicone oil, and the surface is surface-treated so that it is uniformly dispersed and held in the silicone oil.

  A glass substrate was used as the back substrate 52. As the back side electrode 56, comb electrodes as shown in FIG. These are obtained by etching an ITO (300Ω / □) electrode formed on a glass substrate, and the address electrode surrounded by a dotted line has a width of 117 μm and an interelectrode gap of 10 μm (200 dpi). Equivalent), and the length direction is 8 mm.

  A glass substrate was used as the display substrate 50. As the display side electrode 54 (counter electrode), a solid electrode on the entire surface was used. These used what formed the square-shaped gap | interval member 58 (isolation wall) with the colorless and transparent photoresist on the glass substrate in which the ITO electrode in which the whole surface was not etched was formed. The isolation wall has a height of 50 μm, a width of 20 μm, and the inner width of the square is 10 mm both vertically and horizontally. Both the address electrode and the counter electrode were spin-coated with an acrylic copolymer resin to form a surface layer having a thickness of about 200 nm. Place the counter electrode on the horizontal side with the separation wall side up, drop the electrophoretic dispersion liquid in the center, pile up the address electrodes, and fix the peripheral edge with UV curing adhesive. A display medium was produced by sealing.

  When a positive voltage was applied to the electrodes 1 and 2 of the address electrode while 0 V was applied to the counter electrode, the black particles in the electrophoresis solution moved to the counter electrode side, so that it appeared black from the observation side. On the other hand, when a negative voltage is applied to the address electrodes 1 and 2, the black particles move to the address electrode side, so that only white white particles can be seen from the observation side. From this state, after the voltage of the address electrodes 1 and 2 is once set to 0 V, when a positive voltage is applied only to the address electrode 1, only the black particles on the address electrode 1 move to the counter electrode side. I could see black lines displayed at regular intervals on a white background. Here, the observation from the counter electrode side was performed by visual observation and an optical microscope (Keyence, VHX-200).

  Here, the threshold value of the voltage applied to the address electrode for changing from white display to black display was about 5 V, and no change was observed from the observation side even when a voltage lower than this was applied. As the address voltage was increased, the black density gradually increased and was almost saturated at about 12V. The voltage application time was 2 seconds.

  The following Experiment 1 (Comparative Example) was performed using such a display medium.

(Experiment 1-1) Hereinafter, the counter electrode is always grounded (0 V). By applying a voltage of +15 V to the address electrodes 1 and 2 for 2 seconds, and then applying a voltage of −15 V for 2 seconds 5 times, and finally applying 0 V, black display 2 seconds, white display 2 It was confirmed that the display of “seconds” was repeated five times, and finally the entire display was white. This operation is a full reset.

(Experiment 1-2) Thereafter, +15 V was applied to only the electrode 1 for 2 seconds from the white display state, and then returned to 0 V. Evenly spaced black lines were observed on the observation side.

(Experiment 1-3) Subsequently, a voltage of −15 V was applied to the address electrodes 1 and 2 for 2 seconds and then returned to 0 V. This was an operation for whitening the entire surface, and a white display was observed on the observation side.

(Experiment 1-4) Subsequently, a voltage of +15 V was applied to the address electrodes 1 and 2 for 2 seconds and then returned to 0 V. This is an operation for blackening the entire surface. However, although the entire display side is black, the observation side is not uniform, the black portion displayed in black in Experiment 1-3 is lighter, and the black portion displayed in white in Experiment 1-3 is darker. It had been.

Experiment 1-5) Here again, after performing the entire reset operation (black and white 5 times) in Experiment 1-1, the operation in Experiment 1-4 was performed again. As a result, the black display on the entire surface was uniform. It was.

  In Experiment 1-4, the density difference appeared on the observation side black because the distribution of black particles on the address electrode side was not uniform when the entire surface was white in Experiment 1-3. This state is schematically shown in FIG. Here, only the black particles Bk are displayed for the sake of simplicity. First, as shown in FIG. 9A, from the state where all the black particles Bk are moved to the back substrate 52 side, the black particles Bk on the address electrode 1 are moved to the display substrate 50 side in the operation of Experiment 1-2. 9, most of the particles move to the display substrate 50 side, but the particles near the address electrode 2, which is an adjacent electrode, are attracted to the address electrode 2, and as a result, as shown in FIG. As described above, the increase in the amount of the black particles Bk existing in the address electrode 2 is the reason why the altitude is increased later. Further, the black particles Bk moved to the display-side electrode 54 side also spread due to the bending of the electric field or the repulsive action between the particles, which later causes the concentration to become thin. When the operation in Experiment 1-3 is performed in this state, as shown in FIG. 9C, the particles on the display substrate 50 side are almost translated and returned to the address electrode side. Particles on 1 decrease from the beginning and increase at address electrode 2. Therefore, when the operation in Experiment 1-4 is performed, as shown in FIG. 9D, the display reflects the non-uniform distribution on the address electrode side as it is.

  Here, when the operation of Experiment 1-5 is performed, the black particles are reciprocated many times, the particles are agitated in the electrophoresis solution, and the uniform distribution is obtained again by uniformizing the particle distribution. However, since the black particles Bk are reciprocated many times, meaningless display of the entire black-white area is repeated on the observation side.

Then, the following experiment 2 was implemented (Example).
Experiment 2-1) Same as Experiment 1-1 (full reset)
Experiment 2-2) Same as Experiment 1-2 (black line display)
Experiment 2-3) Same as Experiment 1-3 (all white display)
Experiment 2-4) First, a voltage of 4 V was applied to the address electrode 1 and simultaneously, a voltage of 0 V was applied to the address electrode 2 for 0.5 seconds. Subsequently, a voltage of 0 V was applied to the address electrode 1 and simultaneously, a voltage of 4 V was applied to the address electrode 2 for 0.5 seconds. After repeating these five times, both address electrodes were set to 0 V (application of the first voltage). During this time, the observation side remained entirely white.
Experiment 2-5) In the same manner as Experiment 1-4, when +15 V was applied to the address electrodes 1 and 2 for 2 seconds, the entire display was black. At this time, unlike Experiment 1-4, the entire surface was uniform black.

  This is considered to be because the black particles Bk on the address electrode side were agitated and the distribution became uniform in the operation of Experiment 2-4. As described above, when a low voltage is applied between adjacent address electrodes, not all particles move, but extra particles (particles stacked more than necessary) move preferentially. It is thought that it was averaged and made uniform.

(Supplementary experiment of Example 1)
Here, if only Experiment 2-2 (black line display) and Experiment 2-3 (full white display) are repeated continuously several times, even if initialization of Experiment 2-4 is performed, Experiment 2- Unevenness appears in the all black display of 5. This seems to be mainly due to the uneven distribution of particles caused by repeatedly writing the same image. In that case, the operation of Experiment 2-4 is performed a few times to make the all black display of Experiment 2-5 uniform. Thus, it was found that the particles can be made uniform by controlling the number of times of application of the first voltage according to the display history.

  For example, when the operation in Experiment 2-4 is repeated twice, the whiteness on the observation side may slightly decrease. This is because the black particles diffused to the observation side due to the long stirring time. In that case, between the first and second operations, −15 V is applied to all the address electrodes for 1 second to pull the particles back to the address electrode side, thereby preventing the whiteness on the observation side from decreasing. I was able to.

  Furthermore, in Experiment 2-4, 4V was applied to one address electrode for 0.5 seconds, but instead, a voltage of + 6V was applied for 0.2 seconds, and then a voltage of + 3.5V was added to 0.3 seconds for a total of 0 seconds. The voltage may be applied for 5 seconds. In that case, the number of repetitions of voltage application could be sufficiently initialized by 4 times, and there was no problem such as a decrease in whiteness on the observation side. In that case, a condition is necessary for the time integration of voltage application to be substantially constant, but the condition may be determined by confirming actual display.

(Example 2)
The same electrophoresis solution as in Example 1 was used. A TFT substrate having a diagonal size of 5 inches and a dot number of 800 × 600 (200 dpi) was used as the address side substrate (back substrate). The pitch of the address pixels is about 127 μm, and the distance between adjacent address electrodes is about 20 to 30 μm. The counter substrate (display substrate) is a PET film with ITO (300Ω / □) coated on the entire surface, and lattice-shaped isolation walls (height 50 μm, lattice spacing 508 μm, lattice width 20 μm) formed of photoresist. Was used. Both the address substrate and the counter substrate were spray-coated with an acrylic copolymer resin to form a surface layer having a thickness of about 200 nm. After applying a urethane-based adhesive to the upper end of the isolation wall formed on the counter substrate, an electrophoretic solution was injected into the isolation wall, and the address substrate was superimposed and bonded from above. In this way, there is a configuration in which 4 × 4 address electrodes are present in one lattice cell constituted by the isolation walls. A display experiment was carried out using an area of 16 × vertical 16 × lattice and 64 × vertical 64 × 64 in the address pixel (this region is described as the entire surface) out of the fabricated ones.

Experiment 3 was performed using the display medium thus manufactured (Comparative Example).
(Experiment 3-1) Hereinafter, the counter electrode is always 0V. By repeating the pattern of applying + 15V voltage to all address electrodes for 2 seconds and applying -15V voltage for 2 seconds five times, and finally applying 0V voltage, black display is 2 seconds and white display is 2 seconds. It was confirmed that the display was repeated five times, and finally a white display was made on the entire surface (full surface reset).
(Experiment 3-2) One pixel line (1 × 40 pixels, two in parallel at 8 pixel pitch) L1 as shown in FIG. 10 and two pixel lines as shown in FIG. An address electrode that draws a total of four lines of L2 (2 × 40 pixels, two in parallel at 8 pixel pitch) was selected, a voltage of +15 V was applied for 2 seconds, and then returned to 0 V. The pixels were selected so that the longitudinal direction of the line pixels did not contact the isolation wall (gap member 58). From the observation side, the black one-pixel line and the two-pixel line could be clearly observed.
(Experiment 3-3) Subsequently, a voltage of −15 V was applied to all the address electrodes for 2 seconds, and then returned to 0 V. This was an operation for whitening the entire surface, and a white display was observed on the observation side.
(Experiment 3-4) Subsequently, a voltage of +15 V was applied to all the address electrodes for 2 seconds, and then returned to 0 V. This is an operation for displaying the entire surface in black, but the black density of the portion where the line was displayed in Experiment 3-3 was clearly reduced, and it appeared that a thin white line was displayed on the black background. This is the same situation as in Experiment 1-4, and the main cause is that the black particles in the line portion moved to the periphery of the line when the line display was performed in Experiment 3-2.
(Experiment 3-5) Subsequently, after performing the operation of resetting the entire surface of Experiment 3-1, confirming that white was displayed on the entire surface, the operation of Experiment 3-4 was performed. Displayed in black.

Then, the following experiment 4 was implemented (Example).
(Experiment 4-1) Same as Experiment 3-1 (Experiment 4-2) Same as Experiment 3-2 (Experiment 4-3) Same as Experiment 3-3 (Experiment 4-4) Each surrounded by an isolation wall Among the address pixels in the lattice cell, a voltage of +4 V is applied to the back side electrode 56D at the hatched position in FIG. 5A, and at the same time, a voltage of 0 V is applied to the other back side electrode 56E for 0.5 seconds ( Step 1), and subsequently, an operation of applying a voltage of + 4V to the hatched back electrode 56E in FIG. 5B and simultaneously applying a voltage of 0V to the other back electrode 56D for 0.5 seconds (Step 2). Was repeated five times (Step 1 → Step 2 → Step 1 →...), And finally all the address electrodes were set to 0V. During this time, the observation side was entirely white and nothing was observed (application of the first voltage).
(Experiment 4-5) When a voltage of +15 V was applied to all address electrodes for 2 seconds in the same manner as in Experiment 3-4, black display was obtained on the entire surface. At this time, unlike Experiment 3-4, the entire surface was uniform black.

  This is considered to be because the black particles Bk on the address substrate side were agitated by the operation of Experiment 4-4 and the distribution became uniform as in Experiment 2-4.

The following experiment 5 was performed in the same manner as the experiment 4 (Example: another uniform pattern).
(Experiment 5-1) Same as Experiment 4-1 (Experiment 5-2) Same as Experiment 4-2 (Experiment 5-3) Same as Experiment 4-3 (Experiment 5-4) Uniformization shown in Experiment 4-4 In this operation, exactly the same experiment was conducted except that the pattern shown in FIG. 6 was used instead of the pattern shown in FIGS. That is, first, a voltage of +4 V is applied to the back-side electrode 56F in the hatched position in FIG. 6A, and simultaneously, a voltage of 0 V is applied to the other back-side electrode 56 for 0.5 seconds (Step 1). A voltage of + 4V is applied to the back side electrode 56F at the position hatched in 6 (B), and at the same time, a voltage of 0V is applied to the other back side electrode 56 for 0.5 seconds (Step 2), and then FIG. 6 (C). A voltage of + 4V was applied to the back side electrode 56F in the hatched position at the same time, and a voltage of 0V was applied to the other back side electrode 56 for 0.5 seconds (Step 3), followed by hatching in FIG. 6 (D). A series of operations of applying a voltage of +4 V to the back electrode 56F at the position and simultaneously applying a voltage of 0 V to the other back electrode 56 for 0.5 seconds (Step 4) is repeated three times (Step 1 → St p2 → Step3 → Step4 → Step1 → ···), last in all of the address electrode was to 0V. During this time, the entire surface of the observation side remained white.
(Experiment 5-5) In the same manner as Experiment 4-5, when +15 V was applied to all the address pixels for 2 seconds, the entire surface was displayed in black. At this time, unlike Experiment 3-4, the entire surface was uniform black.

  This is considered to be because the black particles Bk on the address substrate side were agitated by the operation of Experiment 5-4 and the distribution became uniform as in Experiment 2-4.

(Supplementary experiment of Example 2)
In Experiment 3, as a pixel and a pixel line, a line pattern that does not contact the isolation wall as shown in FIGS. Here, when each line is in contact with the isolation wall, the particles do not diffuse beyond the isolation wall, so the same result is obtained except that the concentration unevenness appearing in Experiment 3-4 is slightly smaller. Obtained. In Experiment 4 and Experiment 5, the same result was obtained whether or not the line pattern was in contact with the isolation wall.

  In Experiment 3 to Experiment 5, the application of the first voltage was performed on all 16 × 16 cells (entire surface), but the first voltage was not necessarily applied to cells that did not display a line, for example. It is not necessary to apply or the number of repetitions of applying the first voltage can be reduced. As described above, it is possible to select a cell that makes particles uniform according to the image pattern displayed immediately before, or to change the application condition of the first voltage. Alternatively, it is possible to determine whether or not to apply the first voltage by referring to not only the previous image but also the display history information so far, and to set different application conditions for the first voltage. .

(Example 3)
As an electrophoretic solution, a central particle size of about 0.5 μm and uncharged white particles of about 25 mass%, a central particle size of about 0.5 μm and positively charged cyan particles (C particles) of about 1 mass%, About 10% by mass of positively charged red particles (R particles) having a diameter of about 10 μm and dispersed in silicone oil (Shin-Etsu Silicone, KF-96L-2cs) were used. Using this electrophoresis solution, a display medium was produced in the same manner as in Example 1.

  The threshold characteristics in this case are shown in FIG. 12 (two particles with the same polarity). First, when −12 V or less, for example, −15 V, is applied to both the address electrodes 1 and 2, both C particles and R particles are attracted to the address side, and white display is obtained. When the voltage of the address electrode is gradually increased, the R particles start to move to the observation side at + 2V, and move completely to + 6V and become red. When further increased, the C particles begin to move to the observation side at +7 V, and move completely to +12 V and become black display. Here, even if +12 V or more, for example, +15 V is applied from the beginning, this state is obtained. When the voltage is gradually lowered from this state, the R particles start to move to the address side at −2V, and move completely at −6V to display cyan. When the voltage is further lowered, the C particles start to move to the address side at -7V, and move completely at -12V or less to return to white display.

The following experiment 6 (comparative example: black line) was performed using such a display medium.
(Experiment 6-1) Hereinafter, the counter electrode is always grounded (0 V). By repeating the pattern of applying a voltage of + 15V for 2 seconds to the address electrodes 1 and 2 and then applying a voltage of −15V for 2 seconds 5 times, and finally applying 0V, white display 2 The display of “second” is repeated five times, and finally it is confirmed that the entire white display is obtained (entire reset).
(Experiment 6-2) Then, from the state of white display, a voltage of +15 V was applied to only the electrode 1 for 2 seconds, and then returned to 0 V. Evenly spaced black lines were observed on the observation side.
(Experiment 6-3) Subsequently, a voltage of −15 V was applied to the address electrodes 1 and 2 for 2 seconds and then returned to 0 V. This was an operation for whitening the entire surface, and a white display was confirmed on the observation side.
(Experiment 6-4) Subsequently, a voltage of +15 V was applied to the address electrodes 1 and 2 for 2 seconds and then returned to 0 V. This is an operation for displaying the entire surface in black. However, although the entire surface is displayed in black, it is not uniform, and the black portion displayed in Experiment 6-2 is thin, and is displayed in white in Experiment 6-2. The darker part was displayed darker. Also, the color around the boundary of the line was blurred.
(Experiment 6-5) After the operation of resetting the entire surface in Experiment 6-1 (black and white 5 times) was performed again, the operation of Experiment 6-4 was performed again. As a result, the black display on the entire surface was uniform. there were.

  These results were the same as those in Experiment 1 of Example 1.

Subsequently, the following experiment 7 (Example: black line) was performed.
(Experiment 7-1) Same as Experiment 6-1 (white display with full reset)
(Experiment 7-2) Same as Experiment 6-2 (black line display)
(Experiment 7-3) Same as Experiment 6-3 (full white display)
(Experiment 7-4) First, a voltage of 2 V was applied to the address electrode 1 and simultaneously, a voltage of 0 V was applied to the address electrode 2 for 0.5 seconds. Subsequently, a voltage of 0 V was applied to the address electrode 1 and simultaneously, a voltage of 2 V was applied to the address electrode 2 for 0.5 seconds. After repeating these five times, both address electrodes were set to 0 V (application of the first voltage). During this time, the observation side remained entirely white.
(Experiment 7-5) When the entire surface was displayed in black by the same operation as Experiment 6-4, the density unevenness and the color blur observed in Experiment 6-4 were not observed. This is presumably because the particles on the address substrate side were agitated and the distribution became uniform in the operation of Experiment 7-4. A voltage of 2V is sufficient to stir R particles but small to stir C particles. However, in reality, when the R particles are agitated, it is considered that the C particles are agitated by the collision of the R particles, the flow of the medium, and the like, and the C particles are also agitated.

(Supplementary experiment of Example 3: other colors)
Here, the black line was displayed in Experiment 7-2, but the applied voltage in Experiment 7-2 was changed to + 6V instead of + 15V to be red, and in Experiment 7-5 to + 6V to make the entire surface red. Even with this, a display with no unevenness was obtained, and the effect of the present invention was confirmed.

  Similarly, in Experiment 7-2, a voltage of -6V was applied following the voltage of + 15V to display a cyan line, and even in the entire cyan display in Experiment 7-5, a uniform display without unevenness was obtained. .

Example 4
As an electrophoretic solution, a central particle size of about 0.5 μm and uncharged white particles of about 25 mass%, a central particle size of about 0.5 μm and positively charged cyan particles (C particles) of about 1 mass%, About 1% by mass of negatively charged red particles (R particles) having a diameter of about 0.5 μm and dispersed in silicone oil (Shin-Etsu Silicone, KF-96L-2cs) were used. Using this electrophoresis solution, a display medium was produced in the same manner as in Example 1.

  The threshold characteristics in this case are shown in FIG. 13 (two particles with different polarities). First, when a voltage of −12 V or less, for example, −15 V, is applied to both the address electrodes 1 and 2, the C particles are attracted to the address side, and the R particles move to the observation side to display red. From this point, when the voltage of the address electrode is gradually increased, the R particles start to move to the address side at + 2V, and move completely to + 6V to display white. When it is further raised, the C particles start to move to the observation side at +7 V, and move completely to +12 V and become cyan display. Even if + 12V or more, for example, + 15V is first applied, this state is obtained. When the voltage is gradually lowered from this cyan display state, the R particles start to move to the observation side at −2V, and move completely to −6V and become black display. When the voltage is further lowered, the C particles begin to move to the address side at -7V, and move completely to -12V and return to red display.

Using this display medium, the following experiment 8 (comparative example) was performed.
(Experiment 8-1) Hereinafter, the counter electrode is always grounded (0 V). A pattern of + 15V for 2 seconds and then −15V for 2 seconds is repeated 5 times on the address electrodes 1 and 2 and finally a voltage of + 6V is applied, so that cyan display is 2 seconds and red display 2 It was confirmed that the display of “second” was repeated five times, and finally a white display was made on the entire surface (full surface reset).
(Experiment 8-2) Then, from the state of white display, a voltage of +15 V was applied to only the electrode 1 for 2 seconds, a voltage of -6 V was applied for 2 seconds, and finally the voltage was returned to 0 V. Evenly spaced black lines were observed on the observation side.
(Experiment 8-3) Subsequently, a voltage of −15 V was applied to the address electrodes 1 and 2 for 2 seconds (all red), and then a voltage of +6 V was applied for 2 seconds and then returned to 0 V. This was an operation for whitening the entire surface, and a white display was confirmed on the observation side.
(Experiment 8-4) Subsequently, a voltage of +15 V was applied to the address electrodes 1 and 2 for 2 seconds to display the entire surface in cyan. However, the cyan of the line portion (the portion corresponding to the address electrode 1) displayed in black in Experiment 8-2 was displayed slightly lighter. Subsequently, when a voltage of −6 V was applied to the address electrodes 1 and 2 to display black on the entire surface, line-like unevenness was also observed.
(Experiment 8-5) Here, after resetting the entire surface of Experiment 8-1 again to display the entire surface white, the operation of Experiment 8-4 was performed. The display was confirmed.

Subsequently, the following Experiment 9 (Example) was performed.
(Experiment 9-1) Same as Experiment 8-1 (white display with full reset)
(Experiment 9-2) Same as Experiment 8-2 (black line display)
(Experiment 9-3) Same as Experiment 8-3 (full white display)
(Experiment 9-4) First, a voltage of 2 V was applied to the address electrode 1 and simultaneously, a voltage of 0 V was applied to the address electrode 2 for 0.5 seconds. Subsequently, a voltage of 0 V was applied to the address electrode 1 and simultaneously, a voltage of 2 V was applied to the address electrode 2 for 0.5 seconds. After repeating these five times, both address electrodes were set to 0 V (application of the first voltage). During this time, the observation side remained entirely white.
(Experiment 9-5) When the entire surface was displayed in cyan by the same operation as in Experiment 8-4, and then the entire surface was displayed in black, density unevenness and the like were not observed. This is considered to be because the particles on the address substrate side were agitated and the distribution became uniform in the operation of Experiment 9-4. A voltage of 2V is sufficient to stir R particles but small to stir C particles. However, in actuality, when the R particles are agitated, it is considered that the C particles are also agitated by the effect that the agitation of the C particles is promoted by the collision of the R particles and the flow of the medium.

DESCRIPTION OF SYMBOLS 10 Display medium 20 Drive apparatus 30 Voltage application part 40 Computer 40 Control part 50 Display substrate 52 Back substrate 54 Display side electrode 56 Back side electrode 58 Gap member 60 Dispersion medium 62 Colored particle group 64 White particle group 100 Display apparatus

Claims (11)

A pair of substrates having a display substrate and a back substrate disposed opposite to the display substrate with a gap, a display side electrode provided on the display substrate side, and a plurality of back side electrodes provided on the back substrate side And a display medium having at least one kind of particle group sealed between the pair of substrates so as to move between the pair of substrates in accordance with an electric field formed between the pair of substrates.
The particle group is a voltage equal to or lower than a threshold voltage for generating an electric field for separating the particle group from any one of the pair of substrates, and the particle group is disposed on one back side between the adjacent back side electrodes. An apparatus for driving a display medium, comprising: application means for applying a first voltage that is equal to or higher than a voltage for generating an electric field for peeling from an electrode to at least one of the adjacent back side electrodes. Before applying the first voltage, the applying means applies a second voltage that is equal to or higher than the threshold voltage and lower in voltage value or shorter in application time than the voltage for displaying an image. The display medium driving device according to claim 1, wherein the display medium driving device is applied in between. After applying the second voltage, the applying means applies a pull-back voltage having a polarity opposite to that of the second voltage and for pulling the particle group separated from the back substrate side back to the back substrate side. The display medium driving device according to claim 2. The display medium driving apparatus according to claim 1, wherein the applying unit applies the first voltage to at least one of the adjacent back-side electrodes according to a predetermined pattern. The display medium driving device according to claim 4, wherein the predetermined pattern is a checkered pattern or a linear pattern. 5. The display medium driving device according to claim 1, wherein the applying unit applies the first voltage to at least one of the adjacent back-side electrodes according to a display history. 5. The display medium driving device according to claim 1, wherein the applying unit applies the first voltage to at least one of the adjacent back-side electrodes in accordance with an image displayed immediately before. 8. The display medium driving device according to claim 1, wherein the particle groups are a plurality of types of particle groups having different colors and threshold voltages for generating an electric field for peeling from the substrate. The display medium driving device according to claim 1, wherein the display medium includes a dispersion medium that is sealed between the pair of substrates and has a color different from that of the particle group.   A display medium driving program for causing a computer to function as an application unit constituting the display medium driving device according to any one of claims 1 to 9. A pair of substrates having a display substrate and a back substrate disposed opposite to the display substrate with a gap, a display side electrode provided on the display substrate side, and a plurality of back side electrodes provided on the back substrate side And at least one kind of particle group sealed between the pair of substrates so as to move between the pair of substrates in accordance with an electric field formed between the pair of substrates, and a display medium,
A drive device for a display medium according to any one of claims 1 to 9,
A display device comprising:

Images