JP2010197563A - Method for driving electrophoresis display panel, electrophoresis display device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for driving an electrophoresis display panel, an electrophoresis display device and electronic equipment which refresh a display color so that change of the display color may be inconspicuous even when neutral color display is performed to maintain display quality. <P>SOLUTION: In the method for driving the electrophoresis display panel, a refresh process includes: a display color determination process (S100) which determines which of a first color, a second color, and a neutral color between them is the display color of an electrophoresis display layer corresponding to a drive electrode; a refresh electrode selection process (S102) which selects a drive electrode in which the display color of the electrophoresis display layer is the first color or the second color based on determination at the display color determination process; and a pulse application process (S104) which applies a refresh pulse for changing the display color of the electrophoresis display layer to the same color side to the drive electrode selected at the refresh electrode selection process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for driving an electrophoretic display panel, an electrophoretic display device, and an electronic apparatus.

  Conventionally, an electrophoretic dispersion liquid (a display material whose optical properties change in response to electrical stimulation) including a liquid phase dispersion medium and electrophoretic particles is included, and the distribution state of the electrophoretic particles can be controlled by applying an electric field. 2. Description of the Related Art An electrophoretic display device is known as an electro-optical panel (EPD: Electrophoretic Display) that utilizes changes in optical characteristics of an electrophoretic dispersion liquid.

  Since such an electrophoretic display device does not require a backlight, it is possible to reduce the cost and thickness, and in addition to having a wide viewing angle and high contrast, and having a display memory property, the next generation Has attracted attention as a display device.

  However, in reality, as time passes, the electrophoretic particles gradually diffuse into the liquid phase dispersion medium, and the display quality deteriorates. For this reason, a driving method for refreshing the display color at an appropriate timing has been proposed.

Japanese Patent Laid-Open No. 3-213827

  For example, in a monochrome display electrophoretic display device, a refresh pulse having the same polarity as the white write pulse is applied to the drive electrode corresponding to the white display region, or black write is applied to the drive electrode corresponding to the black display region. When a refresh pulse having the same polarity as the pulse is applied, the change in display color is small. Therefore, in such a case, by adopting the driving method described in Patent Document 1, the display color can be refreshed at a level where the user cannot visually recognize the change in the display color.

  However, when the electrophoretic display device applies a pulse having the same polarity as the white writing pulse or a pulse having the same polarity as the black writing pulse to the drive electrode corresponding to the region where the intermediate color (for example, gray) is displayed, the display color The change is large. Therefore, in such a case, if the driving method described in Patent Document 1 is adopted, it is difficult for the user to refresh the display color at a level where the change of the display color cannot be visually recognized, which causes flickering and the like. .

  The present invention has been made in view of the above-described problems. Even when intermediate color display is performed, the display color can be refreshed so that the change in display color is not noticeable, and the display quality can be maintained. An object of the present invention is to provide an electrophoretic display panel driving method, an electrophoretic display device, and an electronic apparatus.

  (1) A method for driving an electrophoretic display panel according to the present invention includes an electrophoretic display layer containing electrophoretic particles, a common electrode layer on which a common electrode is formed, and a drive electrode for driving the electrophoretic display layer. An electrophoretic display panel configured to intervene between the drive electrode layer formed with a holding electrode for maintaining a display color of the electrophoretic display layer corresponding to the drive electrode; and Refreshing the display color of the electrophoretic display layer corresponding to the drive electrode, and the refreshing step includes a first color, a second color and a display color of the electrophoretic display layer corresponding to the drive electrode. Based on the determination in the display color determination step for determining which of these intermediate colors and the display color determination step, the display color of the electrophoretic display layer is the first color or the second color A refresh electrode selection step for selecting a moving electrode, and a pulse application step for applying a refresh pulse for changing the display color of the electrophoretic display layer to the same color side with respect to the drive electrode selected in the refresh electrode selection step It is characterized by including.

  In the case of the segment type electrophoretic display panel, the drive electrode corresponds to the segment electrode. In the case of an active matrix type electrophoretic display panel, the drive electrode corresponds to a pixel electrode.

  According to the present invention, the display color can be refreshed while avoiding the intermediate color display area. Therefore, the display color can be refreshed to maintain the display quality so that the change in the display color is not noticeable even when the intermediate color display is performed.

  (2) In the driving method of the electrophoretic display panel, in the holding step, a common electrode driving pulse that repeats the first potential and the second potential is applied to the common electrode, and the common to the driving electrode. Applying a pulse having the same potential as the electrode drive pulse, and applying the common electrode drive pulse to the common electrode in the pulse applying step, and corresponding to the first color selected in the refresh electrode selection step For the drive electrode, a first potential period that becomes the first potential for changing the display color of the electrophoretic display layer to the first color side during a period in which the common electrode drive pulse becomes the second potential. Is applied as the refresh pulse, and the drive electrode corresponding to the second color selected in the refresh electrode selection step is Applying a pulse including the second potential period as the second potential for changing the display color of the electrophoretic display layer to the second color side as the refresh pulse during a period when the through electrode driving pulse is at the first potential May be.

  (3) In the driving method of the electrophoretic display panel, in the holding step, the first potential that lasts for the first time and the second potential that lasts for the second time are applied to the common electrode at a given period. The common electrode driving pulse is repeatedly applied, and a pulse having the same potential as the common electrode driving pulse is applied to the driving electrode. In the pulse applying step, the length of the first potential period is the second time. Thus, the refresh pulse in which the length of the second potential period is the first time may be applied.

  (4) In the driving method of the electrophoretic display panel, in the pulse applying step, a pulse having the same potential as the common electrode driving pulse is applied to the driving electrodes not selected in the refresh electrode selecting step. Also good.

  (5) In this method of driving an electrophoretic display panel, a period in which the refresh process is performed may be inserted at a periodic timing in a period in which the hold process is performed.

  (6) The method for driving the electrophoretic display panel may further include a rewriting step of rewriting the intermediate color with respect to the driving electrodes not selected in the refresh electrode selection step.

  (7) In the driving method of the electrophoretic display panel, the refresh process and the rewrite process may be performed at different timings.

  (8) In the electrophoretic display device according to the present invention, the electrophoretic display layer including the electrophoretic particles includes a common electrode layer on which a common electrode is formed, and a drive electrode for driving the electrophoretic display layer. An electrophoretic display panel configured to be interposed between the drive electrode layer, and a drive control unit that drives and controls the electrophoretic display panel by supplying a voltage between the common electrode and the drive electrode. The electrophoretic display device includes: a hold process for maintaining a display color of the electrophoretic display layer corresponding to the drive electrode; and a display color of the electrophoretic display layer corresponding to the drive electrode. In the refresh process, it is determined whether the display color of the electrophoretic display layer corresponding to the drive electrode is a first color, a second color, or an intermediate color thereof. Display color determination processing to be performed, and refresh electrode selection processing to select the drive electrode whose display color of the electrophoretic display layer is the first color or the second color based on the determination in the display color determination processing A pulse application process for applying a refresh pulse for changing the display color of the electrophoretic display layer to the same color side is performed on the drive electrode selected in the refresh electrode selection process.

  (9) In this electrophoretic display device, in the hold process, the drive control unit gives the first potential that continues for a first time and the second potential that continues for a second time to the common electrode. And applying a pulse having the same potential as the common electrode drive pulse to the drive electrode. In the pulse application process, the length of the first potential period is The refresh pulse in which the second time period is reached and the length of the second potential period is the first time period may be applied.

  (10) In the electrophoretic display device, the drive control unit applies the common electrode drive pulse that repeats the first potential and the second potential at a given period to the common electrode in the hold process. In addition, a pulse having the same potential as the common electrode drive pulse is applied to the drive electrode, and in the pulse application process, the lengths of the first potential period and the second potential period are set to the given period. The refresh pulse that is ½ of the above may be applied.

(11) In the electrophoretic display device, the drive control unit
In the pulse application process, a pulse having the same potential as the common electrode drive pulse may be applied to the drive electrodes that are not selected in the refresh electrode selection process.

  (12) In this electrophoretic display device, the drive control unit may insert a period for performing the refresh process into a period for performing the hold process at a periodic timing.

  (13) In the electrophoretic display device, the drive control unit may further perform a rewrite process for rewriting the intermediate color on the drive electrodes that are not selected in the refresh electrode selection process.

  (14) In this electrophoretic display device, the drive control unit may perform the refresh process and the rewrite process at different timings.

  (15) An electronic apparatus according to the present invention includes any one of these electrophoretic display devices.

1 is a schematic diagram of an electrophoretic display device according to an embodiment. Schematic of the cross section of an electrophoretic display panel. The timing chart of the voltage applied to a common electrode and a segment electrode (drive electrode). 4A to 4C are schematic diagrams illustrating an operation example of the electrophoretic display panel. The flowchart of a refresh process. The timing chart of the voltage applied to a common electrode and a segment electrode (drive electrode). 7A to 7C are schematic diagrams illustrating an operation example of the electrophoretic display panel. FIG. 10 is a schematic diagram of an electrophoretic display device according to a modification of the embodiment. FIG. 9A to FIG. 9C are configuration examples of electronic devices according to the present embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Electrophoretic display device [Configuration of electrophoretic display device]
FIG. 1 is a schematic diagram of an electrophoretic display device according to this embodiment. The electrophoretic display device 1 includes an electrophoretic display panel 30 and a drive control unit 40 that drives the electrophoretic display panel 30. In the following description, an example in which the electrophoretic display panel 30 is a segmented electrophoretic display panel will be mainly described, but an active matrix electrophoretic display panel may be used. In the present embodiment, an example in which the electrophoretic display panel 30 that displays black (first color), white (second color), and an intermediate color thereof is used as the display color will be described. The color is not limited to these, and various selections are possible.

  The drive control unit 40 may include, for example, a data generation unit 421, a pulse application unit 422, a display color determination unit 423, and a refresh electrode selection unit 424.

  The data generation unit 421 includes an image signal processing circuit and a timing generator, and displays display data indicating images and characters to be displayed on the electrophoretic display panel 30 (for example, black display data corresponding to each segment electrode (drive electrode), White display data, intermediate color display data) and refresh data for maintaining the display. The data generation unit 421 may further include a storage unit (not shown) that stores display data and the like.

  The pulse applying unit 422 applies a common electrode driving pulse to the common electrode of the electrophoretic display panel 30 in conjunction with the output of display data or refresh data from the data transfer unit 421, or the electrophoretic display panel 30 A voltage pulse corresponding to the process is applied to the segment electrode (drive electrode).

  The display color determination unit 423 determines whether the display color corresponding to the segment electrode (drive electrode) of the electrophoretic display panel 30 is black (first color), white (second color), or an intermediate color thereof. To do.

  The refresh electrode selection unit 424 selects a segment electrode (drive electrode) for refreshing the display of the electrophoretic display panel 30 based on the determination by the display color determination unit 423.

  A part or all of the drive control unit 40 may be configured by a semiconductor integrated circuit. In addition, the drive control unit 40 can be realized by a dedicated circuit to perform the above-described control and various types of control of processing to be described later. For example, a CPU (Central Processing Unit) is stored in a storage unit (not illustrated) or the like. It is also possible to function as a computer by executing the control program, and to perform various controls of these processes. That is, the drive control unit 40 may be configured to function as the data generation unit 421, the pulse application unit 422, the display color determination unit 423, and the refresh electrode selection unit 424 according to a control program.

  Further, in the electrophoretic display device 1 including the electrophoretic display panel 30 that performs time display as in the example of FIG. 1, a clock interface 45 that provides information necessary for time display and a user interface that processes input from the user. 44 may be included.

  FIG. 2 is a schematic view of a cross section of the electrophoretic display panel 30. As shown in FIG. 2, in the electrophoretic display panel 30, a counter substrate 20 made of a transparent material such as glass or resin is opposed to a substrate 21. A drive electrode layer 110 in which segment electrodes (drive electrodes) 11A to 11C constituting a plurality of divided electrodes are formed is disposed on the substrate 21 side, and ITO (having high light transmittance and low electrical resistance) is disposed on the counter substrate 20 side. A common electrode layer 100 on which a common electrode 10 made of a transparent conductive material such as Indium Tin Oxide is formed is disposed.

  Further, an electrophoretic display layer 600 including an electrophoretic element 60 containing charged electrophoretic particles is configured to be interposed between the common electrode layer 100 and the drive electrode layer 110. In the electrophoretic element 60, a transparent dispersion liquid, positively charged white particles 61 and negatively charged black particles 62 are encapsulated in transparent microcapsules.

  Note that the common electrode layer 100, the drive electrode layer 110, and the electrophoretic display layer 600 may include an adhesive or a binder material (not shown). Further, the white particles 61 may be negatively charged and the black particles 62 may be positively charged. In this case, the electrical operation of the electrophoretic particles described later is reversed.

  Hereinafter, FIG. 2 will be described on the assumption that the user can recognize the display pattern from the counter substrate side. However, in the embodiment of the present invention, the display pattern is displayed from the substrate side using a transparent material for the substrate 21 or the segment electrode 11 on the substrate side. May be recognized.

[Operating Principle of Electrophoretic Display Panel]
The operation principle of the electrophoretic display panel 30 will be described with reference to FIGS. 3 is a timing chart of voltages applied to the common electrode 10 and the segment electrodes (drive electrodes) 11A to 11C, and FIGS. 4A to 4C are schematic diagrams illustrating an operation example of the electrophoretic display panel 30. FIG. FIG. 4A and 4B, the black arrow indicates the moving direction of black particles, and the white arrow indicates the moving direction of white particles.

  FIG. 3 shows the voltages applied to the common electrode 10 segment electrodes (drive electrodes) 11A, 11B, and 11C in order from the top.

  In the example illustrated in FIG. 3, a common electrode driving pulse that repeats a low level (first potential) and a high level (second potential) at a given period is applied to the common electrode 10. A low level (first potential) voltage is applied to the segment electrode (drive electrode) 11A. A high level (second potential) voltage is applied to the segment electrode (drive electrode) 11B. A pulse having the same potential as the common electrode drive pulse is applied to the segment electrode (drive electrode) 11C. That is, the same pulse as the common electrode drive pulse is applied to the segment electrode (drive electrode) 11C in synchronization with the common electrode drive pulse.

  FIG. 4A illustrates an operation in a period in which the common electrode 10 is at a high level (second potential). In this period, since the segment electrodes (drive electrodes) 11B and 11C are at the high level (second potential), the common electrode 10 and the segment electrode (drive electrode) are between the common electrode 10 and the segment electrode (drive electrode) 11B. There is no potential difference with 11C. Therefore, neither white particles nor black particles move. Therefore, the original display color is maintained as the display color of the electrophoretic display layer 600 corresponding to the segment electrodes (drive electrodes) 11B and 11C.

  On the other hand, since the segment electrode (drive electrode) 11A is at the low level (first potential), a potential difference is generated between the common electrode 10 and the segment electrode (drive electrode) 11A. Due to the electric field generated by this potential difference, in this embodiment, positively charged white particles move to the segment electrode (drive electrode) 11A side, and negatively charged black particles move to the common electrode 10 side. Therefore, the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) 11A changes to the black side (first color side).

  FIG. 4B illustrates an operation in a period in which the common electrode 10 is at a low level (first potential). During this period, since the segment electrodes (drive electrodes) 11A and 11C are at the low level (first potential), the common electrode 10 and the segment electrode (drive electrode) are connected between the common electrode 10 and the segment electrode (drive electrode) 11A. There is no potential difference with 11C. Therefore, neither white particles nor black particles move. Therefore, the display color of the electrophoretic display layer 600 corresponding to the segment electrodes (drive electrodes) 11A and 11C is maintained as the original display color.

  On the other hand, since the segment electrode (drive electrode) 11B is at a high level (second potential), a potential difference is generated between the common electrode 10 and the segment electrode (drive electrode) 11B. In this embodiment, positively charged white particles move to the common electrode 10 side, and negatively charged black particles move to the segment electrode (drive electrode) 11B side by the electric field generated by this potential difference. Accordingly, the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) 11B changes to the white side (second color side).

  By repeating these operations, as shown in FIG. 4C, the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) 11A is set to black (first color), and the segment electrode (drive electrode) is displayed. ) The display color of the electrophoretic display layer 600 corresponding to 11B is white (second color), and the display color based on the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) 11C (FIG. In C), the intermediate color can be left as it is.

  In addition, by adjusting the application time of the first potential or the second potential applied to the segment electrode (driving electrode) or combining them, the electrophoretic display layer 600 can display a plurality of gradation intermediate colors. it can.

  As described above, according to the driving method in which the potential of the common electrode 10 and the potential of the segment electrode (drive electrode) are both variable, the drive is performed with two values of Low level (first potential) and High level (second potential). be able to. In addition, the segment electrode (driving electrode) has three types of control: changing the display color to the black side (first color side), changing the display color to the white side (second color side), and maintaining the display color. Can be done every.

[Driving method of electrophoretic display panel]
The driving method of the electrophoretic display panel 30 according to the present embodiment includes a hold process for maintaining the display color of the electrophoretic display layer 600 corresponding to the segment electrode (driving electrode). In the holding step, for example, a common electrode driving pulse that repeats the first potential and the second potential is applied to the common electrode 10, and a pulse having the same potential as the common electrode driving pulse is applied to the segment electrode (driving electrode). (That is, the same pulse as the common electrode drive pulse may be applied to the segment electrode (drive electrode) in synchronization with the common electrode drive pulse).

  In the electrophoretic display device 1 according to this embodiment, the drive control unit 40 performs the hold process by performing a hold process for maintaining the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode). In the hold process, for example, the pulse applying unit 422 of the drive control unit 40 applies a common electrode drive pulse that repeats the first potential and the second potential to the common electrode 10 and also applies to the segment electrode (drive electrode). Alternatively, a pulse having the same potential as the common electrode drive pulse may be applied (that is, the same pulse as the common electrode drive pulse is applied to the segment electrode (drive electrode) in synchronization with the common electrode drive pulse).

  Like the operation of the segment electrode 11C described with reference to FIGS. 3 and 4, the common electrode drive pulse that repeats the first potential and the second potential is applied to the common electrode 10, and the segment electrode (drive electrode) is applied. On the other hand, when a pulse having the same potential as the common electrode drive pulse is applied, no potential difference is generated between the common electrode 10 and the segment electrode (drive electrode). Therefore, neither white particles nor black particles move. Therefore, in the hold process, the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) is maintained as the original display color.

  The driving method of the electrophoretic display panel 30 according to the present embodiment includes a refresh process for refreshing the display color of the electrophoretic display layer 600 corresponding to the segment electrode (driving electrode). FIG. 5 is a flowchart of the refresh process.

  First, a display color determination step for determining whether the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) is black (first color), white (second color), or an intermediate color thereof. Perform (step S100). In the electrophoretic display device 1 according to the present embodiment, the display color determination unit 423 of the drive control unit 40 determines that the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) is black (first color), A display color determination process is performed by performing a display color determination process for determining whether the color is white (second color) or an intermediate color thereof.

  In the display color determination step, for example, the display data generated by the data generation unit 421 corresponding to each segment electrode (drive electrode) and stored in the storage unit (not shown) includes black display data, white display data, The display color determination means 423 may determine based on which of the intermediate color display data.

  After step S100, based on the determination in the display color determination step, refresh that selects a segment electrode (drive electrode) whose display color of the electrophoretic display layer 600 is black (first color) or white (second color) An electrode selection process is performed (step S102). In the electrophoretic display device 1 according to the present embodiment, the refresh electrode selection unit 424 of the drive control unit 40 determines that the display color of the electrophoretic display layer 600 is black (first color) based on the determination in the display color determination process. ) Or white (second color), a refresh electrode selection process is performed by performing a refresh electrode selection process for selecting a segment electrode (drive electrode).

  After step S102, a pulse application step of applying a refresh pulse for changing the display color of the electrophoretic display layer 600 to the same color side is performed on the segment electrode (drive electrode) selected in the refresh electrode selection step. In the electrophoretic display device 1 according to the present embodiment, the pulse application unit 422 of the drive control unit 40 displays the display color of the electrophoretic display layer 600 with respect to the segment electrode (drive electrode) selected in the refresh electrode selection process. The pulse application process is performed by performing a pulse application process of applying a refresh pulse that changes the color to the same color side.

  In the pulse application step, a refresh pulse that changes to the black side (first color side) is applied to the segment electrode (drive electrode) whose display color of the electrophoretic display layer 600 is black (first color), and electrophoresis is performed. A refresh pulse for changing to the white side (second color side) is applied to the segment electrode (drive electrode) whose display color of the display layer 600 is white (second color).

  As a result, the black (first color) display whose display quality has deteriorated over time is changed to a good black side (first color side), and the white (second color) display whose display quality has deteriorated is changed to good white. It can be changed to the side (second color side). Therefore, the display quality deteriorated with the passage of time can be returned to a good state again.

  Further, no refresh pulse is applied to the segment electrode (drive electrode) whose display color of the electrophoretic display layer 600 is an intermediate color. That is, the display color can be refreshed while avoiding the intermediate color display area.

  When the display color of the electrophoretic display layer 600 is an intermediate color, if the refresh pulse is applied to the segment electrode (drive electrode), the display color changes so much that the display color is refreshed at a level where the user cannot visually recognize the change in the display color. Is difficult to do.

  Therefore, even when intermediate color display is performed, the display color change is conspicuous even when intermediate color display is performed by selectively refreshing the black (first color) display or white (second color) display region. The display color can be refreshed so that the display quality can be maintained.

  Next, a specific example of the pulse applying process will be described with reference to FIGS. FIG. 6 is a timing chart of voltages applied to the common electrode and the segment electrode (drive electrode) in the method for driving an electrophoretic display panel according to the present embodiment. FIGS. 6 is a schematic diagram illustrating an operation example of the electrophoretic display panel 30. FIG. 7A and 7B, the black arrow indicates the moving direction of black particles, and the white arrow indicates the moving direction of white particles.

  7A to 7C show, from left to right, a segment electrode (drive electrode) 11A corresponding to black (first color) display and a segment electrode (drive electrode) corresponding to white (second color) display. 11B, a segment electrode (drive electrode) 11C corresponding to intermediate color display, an electrophoretic display layer 600, and the like.

  As described above, in the refresh electrode selection step, the segment electrode (drive electrode) whose display color of the electrophoretic display layer 600 is black (first color) or white (second color) is selected. Electrodes) 11A and 11B are selected.

  FIG. 6 shows the voltages applied to the common electrode 10 segment electrodes (drive electrodes) 11A, 11B, and 11C in order from the top.

  A common electrode driving pulse that repeats a low level (first potential) and a high level (second potential) is applied to the common electrode 10.

  For the segment electrode (drive electrode) 11A corresponding to black (first color), the display color of the electrophoretic display layer 600 is changed to the black side (during the period when the common electrode drive pulse is at the Hihg level (second potential). A pulse including a first potential period that becomes a low level (first potential) to be changed to the first color side is applied as a refresh pulse. In this embodiment, in the period excluding the first potential period, a pulse having the same potential as the common electrode drive pulse is applied (that is, the same pulse as the common electrode drive pulse is applied in synchronization with the common electrode drive pulse). )is doing.

  For the segment electrode (drive electrode) 11B corresponding to white (second color), the display color of the electrophoretic display layer 600 is set to the white side (in the period when the common electrode drive pulse is at the low level (first potential). A pulse including a second potential period that becomes a high level (second potential) to be changed to the second color side is applied as a refresh pulse. In this embodiment, in the period excluding the second potential period, a pulse having the same potential as the common electrode drive pulse is applied (that is, the same pulse as the common electrode drive pulse is applied in synchronization with the common electrode drive pulse). )is doing.

  A pulse having the same potential as the common electrode drive pulse is applied to the segment electrode (drive electrode) 11C corresponding to the intermediate color (that is, the same pulse as the common electrode drive pulse is applied in synchronization with the common electrode drive pulse). is doing.

  The operation of the electrophoretic display panel 30 in the first potential period is shown in FIG. In this period, since the common electrode 10 and the segment electrodes (drive electrodes) 11B and 11C are at the high level (second potential), the common electrode 10 and the segment electrodes are disposed between the common electrode 10 and the segment electrodes (drive electrode) 11B. There is no potential difference with the (drive electrode) 11C. Therefore, neither white particles nor black particles move. Therefore, the original display color is maintained as the display color of the electrophoretic display layer 600 corresponding to the segment electrodes (drive electrodes) 11B and 11C.

  On the other hand, since the segment electrode (drive electrode) 11A is at the low level (first potential), a potential difference is generated between the common electrode 10 and the segment electrode (drive electrode) 11A. Due to the electric field generated by this potential difference, in this embodiment, positively charged white particles move to the segment electrode (drive electrode) 11A side, and negatively charged black particles move to the common electrode 10 side. Therefore, the display color of the electrophoretic display layer 600 corresponding to the segment electrode (drive electrode) 11A changes from black (first color) whose display quality has deteriorated over time to the black side (first color side).

  The operation of the electrophoretic display panel 30 in the second potential period is shown in FIG. During this period, since the common electrode 10 and the segment electrodes (drive electrodes) 11A and 11C are at the low level (first potential), the common electrode 10 and the segment electrodes are between the common electrode 10 and the segment electrode (drive electrode) 11A. There is no potential difference with the (drive electrode) 11C. Therefore, neither white particles nor black particles move. Therefore, the display color of the electrophoretic display layer 600 corresponding to the segment electrodes (drive electrodes) 11A and 11C is maintained as the original display color.

  On the other hand, since the segment electrode (drive electrode) 11B is at a high level (second potential), a potential difference is generated between the common electrode 10 and the segment electrode (drive electrode) 11B. In this embodiment, positively charged white particles move to the common electrode 10 side, and negatively charged black particles move to the segment electrode (drive electrode) 11B side by the electric field generated by this potential difference. Therefore, the display color of the electrophoretic display layer 600 corresponding to the segment electrode (driving electrode) 11B changes from white (second color) whose display quality has deteriorated over time to the white side (second color side).

  A pulse having the same potential as the common electrode drive pulse is applied to the segment electrode (drive electrode) 11A excluding the first potential period, the segment electrode 11B excluding the second potential period, and the segment electrode (drive electrode) 11C corresponding to the intermediate color. Applied. Therefore, as shown in FIG. 7C, the display color of the electrophoretic display layer 600 is maintained as the original display color.

  That is, the original display color is maintained for the intermediate color display region corresponding to the segment electrode (drive electrode) 11C. Therefore, by applying a refresh pulse as shown in FIG. 6, it is possible to selectively refresh the black (first color) display area and the white (second color) display area while avoiding the intermediate color display area. it can.

  In the present embodiment, the low level (first potential) that continues for the first time and the high level (second potential) that continues for the second time with respect to the common electrode 10 in both the hold process and the pulse application process. A common electrode driving pulse that repeats the above in a given cycle is applied. In this case, by applying a refresh pulse in which the length of the first potential period is the second time and the length of the second potential period is the first period, the above-described pulse applying process can be realized with simple control. Can do. In the example shown in FIG. 6, since the common electrode driving pulse having the same first time and second time is applied to the common electrode 10, the lengths of the first potential period and the second potential period are equal to the common electrode driving. A refresh pulse that is ½ of the pulse period is applied.

  Further, a period for performing the refresh process may be inserted at a periodic timing in a period for performing the hold process. For example, the refresh process may be performed at a timing before the time when a normal user can visually recognize the deterioration of display quality. By performing the refresh process at periodic timing, the display quality of the electrophoretic display panel 30 can be maintained.

  Furthermore, a rewriting step of rewriting the intermediate color with respect to the segment electrode (drive electrode) that has not been selected in the refresh electrode selection step may be further included. In the electrophoretic display device 1 according to the present embodiment, the rewrite operation in which the pulse applying unit 422 of the drive control unit 40 rewrites the intermediate color to the segment electrode (drive electrode) not selected in the refresh electrode selection process. A rewriting process is performed by performing the processing. In the rewriting process, for example, a common electrode driving pulse may be applied to the common electrode 10 and a driving pulse for rewriting the intermediate color may be applied to the segment electrode (driving electrode).

  By rewriting the intermediate color, the display quality of the intermediate color can be maintained.

  Further, the refresh process and the rewrite process may be performed at different timings. For example, the rewriting process may be performed at a period longer than the period of performing the refreshing process, or the rewriting process may be performed at the same timing as the display color changing process of other segment electrodes (drive electrodes). As a result, the refresh operation for the intermediate color can be performed at a relatively inconspicuous timing.

[Modification]
In the above-described embodiment, the example using the segment type electrophoretic display panel 30 has been described. However, the electrophoretic display panel 30 may be an active matrix type electrophoretic display panel. FIG. 8 is a schematic diagram of an electrophoretic display device according to a modification of the present embodiment.

  In FIG. 8, an electrophoretic display panel 30 is an active matrix type electrophoretic display panel. The electrophoretic display panel 30 includes a TFT circuit including a pixel electrode (drive electrode) corresponding to each pixel, a TFT (thin film transistor) element 353, and the like. In addition to the data generation unit 421, the pulse application unit 422, the display color determination unit 423, and the refresh electrode selection unit 424, the drive control unit 40 outputs a scanning line signal to the scanning line 351 of the TFT circuit. And a scanning line driving circuit 431 that outputs data line signals to the data line 352 of the TFT circuit. The pulse applying unit 422 of the drive control unit 40 may apply a refresh pulse or a drive pulse for rewriting intermediate colors to the pixel electrode (drive electrode) via the scanning line drive circuit 431 and the data line drive circuit 432. .

  The operation in the active matrix type electrophoretic display panel is the same as the operation described with reference to FIGS. 2 to 7 in which the segment electrode is replaced with the pixel electrode. When the segment type electrophoretic display panel is used Has the same effect as.

2. Electronic Device FIGS. 9A to 9C are configuration examples of electronic devices according to the present embodiment. 9A shows a mobile phone 3000, FIG. 9B shows a wristwatch 4000, and FIG. 9C shows a notebook computer 5000.

  Each of the mobile phone 3000, the wristwatch 4000, and the notebook computer 5000 according to the present embodiment includes the electrophoretic display device 1, and uses the electrophoretic display panel 30 of the electrophoretic display device 1 as the display unit 1100.

  As a result, it is possible to realize an electronic device capable of maintaining the display quality by refreshing the display color so that the change in the display color is not noticeable even when the intermediate color display is performed.

  In addition, this invention is not limited to this Embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 Electrophoretic display apparatus, 10 Common electrode, 11A-11C Segment electrode (drive electrode), 20 Opposite substrate, 21 Substrate, 30 Electrophoretic display panel, 40 Drive control part, 44 User interface, 45 Clock part, 60 Electrophoretic element , 61 White particles, 62 Black particles, 100 Common electrode layer, 110 Drive electrode layer, 351 Scan line, 352 Data line, 353 TFT element, 421 Data generation means, 422 Pulse application means, 423 Display color determination means, 424 Refresh electrode Selection means, 431 scanning line drive circuit, 432 data line drive circuit, 600 electrophoretic display layer, 1100 display unit, 3000 mobile phone, 4000 watch, 5000 notebook computer

Claims (15)

An electrophoretic display layer containing electrophoretic particles is interposed between a common electrode layer on which a common electrode is formed and a drive electrode layer on which a drive electrode for driving the electrophoretic display layer is formed. An electrophoretic display panel driving method comprising:
A hold step for maintaining the display color of the electrophoretic display layer corresponding to the drive electrode;
Refreshing the display color of the electrophoretic display layer corresponding to the drive electrode,
The refresh process includes
A display color determination step for determining whether the display color of the electrophoretic display layer corresponding to the drive electrode is a first color, a second color, or an intermediate color thereof;
A refresh electrode selection step of selecting the drive electrode whose display color of the electrophoretic display layer is the first color or the second color based on the determination in the display color determination step;
An electrophoretic display comprising: applying a refresh pulse for changing a display color of the electrophoretic display layer to the same color side with respect to the drive electrode selected in the refresh electrode selecting step. Panel drive method. The method for driving an electrophoretic display panel according to claim 1,
In the holding step,
Applying a common electrode driving pulse that repeats a first potential and a second potential to the common electrode, and applying a pulse having the same potential as the common electrode driving pulse to the driving electrode;
In the pulse applying step,
While applying the common electrode driving pulse to the common electrode,
For the drive electrode corresponding to the first color selected in the refresh electrode selection step, the display color of the electrophoretic display layer is changed to the first color during a period when the common electrode drive pulse is at the second potential. Applying a pulse including a first potential period to be the first potential to be changed to one color side as the refresh pulse;
For the drive electrodes corresponding to the second color selected in the refresh electrode selection step, the display color of the electrophoretic display layer is changed to the first color during a period when the common electrode drive pulse is at the first potential. A driving method of an electrophoretic display panel, wherein a pulse including a second potential period that is the second potential to be changed to the two-color side is applied as the refresh pulse. The method for driving an electrophoretic display panel according to claim 2,
In the holding step,
Applying the common electrode driving pulse that repeats the first potential that continues for a first time and the second potential that continues for a second time at a given period to the common electrode, and Apply a pulse with the same potential as the common electrode drive pulse,
In the pulse applying step,
The method of driving an electrophoretic display panel, wherein the refresh pulse is applied such that the length of the first potential period is the second time and the length of the second potential period is the first time. The method for driving an electrophoretic display panel according to any one of claims 2 and 3,
In the pulse applying step,
A driving method of an electrophoretic display panel, wherein a pulse having the same potential as the common electrode driving pulse is applied to the driving electrodes that are not selected in the refresh electrode selecting step. The method for driving an electrophoretic display panel according to claim 1,
A method for driving an electrophoretic display panel, wherein a period for performing the refreshing step is inserted at a periodic timing in a period for performing the holding step. The method for driving an electrophoretic display panel according to claim 1,
The method of driving an electrophoretic display panel, further comprising a rewriting step of rewriting the intermediate color to the driving electrodes not selected in the refresh electrode selection step. The method for driving an electrophoretic display panel according to claim 6,
The method for driving an electrophoretic display panel, wherein the refreshing step and the rewriting step are performed at different timings. An electrophoretic display layer containing electrophoretic particles is interposed between a common electrode layer on which a common electrode is formed and a drive electrode layer on which a drive electrode for driving the electrophoretic display layer is formed. An electrophoretic display panel;
An electrophoretic display device including a drive control unit that drives and controls the electrophoretic display panel by supplying a voltage between the common electrode and the drive electrode;
The drive control unit
Hold processing for maintaining the display color of the electrophoretic display layer corresponding to the drive electrode;
Performing a refresh process for refreshing the display color of the electrophoretic display layer corresponding to the drive electrode;
In the refresh process,
A display color determination process for determining whether the display color of the electrophoretic display layer corresponding to the drive electrode is a first color, a second color, or an intermediate color thereof;
A refresh electrode selection process for selecting the drive electrode whose display color of the electrophoretic display layer is the first color or the second color based on the determination in the display color determination process;
An electrophoretic display comprising: applying a refresh pulse for changing a display color of the electrophoretic display layer to the same color side with respect to the drive electrode selected in the refresh electrode selection process. apparatus. The electrophoretic display device according to claim 8.
The drive control unit
In the hold process,
Applying a common electrode driving pulse that repeats a first potential and a second potential to the common electrode, and applying a pulse having the same potential as the common electrode driving pulse to the driving electrode;
In the pulse application process,
While applying the common electrode driving pulse to the common electrode,
For the drive electrodes corresponding to the first color selected in the refresh electrode selection process, the display color of the electrophoretic display layer is changed to the first color during a period in which the common electrode drive pulse is at the second potential. Applying a pulse including a first potential period to be the first potential to be changed to one color side as the refresh pulse;
For the drive electrode corresponding to the second color selected in the refresh electrode selection process, the display color of the electrophoretic display layer is changed to the first color during a period when the common electrode drive pulse is at the first potential. An electrophoretic display device, wherein a pulse including a second potential period that is the second potential to be changed to a two-color side is applied as the refresh pulse. The method for driving an electrophoretic display panel according to claim 9,
The drive control unit
In the hold process,
Applying the common electrode driving pulse that repeats the first potential that continues for a first time and the second potential that continues for a second time at a given period to the common electrode, and Apply a pulse with the same potential as the common electrode drive pulse,
In the pulse application process,
The electrophoretic display device, wherein the refresh pulse is applied such that the length of the first potential period is the second time and the length of the second potential period is the first time. The electrophoretic display device according to any one of claims 9 and 10,
The drive control unit
In the pulse application process,
An electrophoretic display device, wherein a pulse having the same potential as the common electrode drive pulse is applied to the drive electrodes not selected in the refresh electrode selection process. The electrophoretic display device according to any one of claims 8 to 11,
The electrophoretic display device, wherein the drive control unit inserts a period for performing the refresh process at a periodic timing in a period for performing the hold process. The electrophoretic display device according to any one of claims 8 to 12,
The drive control unit
The electrophoretic display device further comprising a rewriting process for rewriting the intermediate color on the drive electrodes not selected in the refresh electrode selection process. The electrophoretic display device according to claim 13,
The drive control unit
An electrophoretic display device, wherein the refresh process and the rewrite process are performed at different timings.   An electronic apparatus comprising the electrophoretic display device according to claim 8.

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