JP2011186147A - Method of driving electrophoretic display device, electrophoretic display device, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of driving an electrophoretic display device or the like for eliminating the afterimage of the contour part of an image while taking DC balance. <P>SOLUTION: The method of driving the electrophoretic display device including a display part comprising pixels capable of displaying at least a first color and a second color includes: a first entire surface rewrite step S1 of performing entire surface drive and displaying a given area in a second color; a first partial rewrite step S2 of rewriting a given visual expression by partial drive inside the given area after the first entire surface rewrite step; a second entire surface rewrite step S5 of performing the entire surface drive and displaying the given area in the first color after the first partial rewrite step is repeated a given number of times; and a second partial rewrite step S6 of rewriting the given visual expression by the partial drive after the second entire surface rewrite step. After the second partial rewrite step is repeated the given number of times, the step returns to the first entire surface rewrite step again. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In recent years, a display panel having a memory property that can hold an image even when the power is turned off has been developed and used in an electronic timepiece or the like. As a display panel having a memory property, an EPD (Electrophoretic Display), that is, an electrophoretic display device, a memory-type liquid crystal display device, and the like are known.

  While the electrophoretic display device has excellent advantages such as wide viewing angle, high contrast, flexibility, and low power consumption because it is a reflective display, it responds to move electrophoretic particles by an electric field. Speed is limited. For this reason, not only full-surface driving for drawing the entire display portion but also partial driving for drawing only a part of the display portion to be rewritten may be used. By appropriately performing partial drive according to the use and situation of the electrophoretic display device, it becomes possible to speed up the response at the time of rewriting.

JP-T-2005-530201

  However, for example, when partial driving is performed only on a part of the pixels (in this case, an image) of the display unit to be rewritten, an oblique electric field is generated between the image and the background pixel. An afterimage may occur along the contour of the image.

  Further, according to Patent Document 1, if the time average of the electric field applied between the electrodes in the electrophoretic display device is not substantially zero, that is, if the DC balance is lost, the operation life of the device may be shortened. That is, in order to ensure long-term reliability of the electrophoretic display device, it is necessary to perform drive control with a DC balance.

  The present invention has been made in view of such problems. According to some aspects of the present invention, it is possible to provide an electrophoretic display device driving method, an electrophoretic display device, and an electronic apparatus that erase afterimages along the contour of an image while maintaining DC balance.

(1) The present invention drives an electrophoretic display device that includes an electrophoretic element including electrophoretic particles between a pair of substrates and includes a display unit including pixels capable of displaying at least a first color and a second color. A first full-surface rewriting step of performing a whole-surface driving for applying a voltage to the electrophoretic element in all regions of the display unit and displaying a given region in the display unit in the second color. And a first partial rewriting step of performing rewriting of a given visual expression by partial driving in which a voltage is applied to the electrophoretic element within the given region after the first full rewriting step; After the partial rewriting process is repeated a given number of times, the whole surface driving is performed, and the given area is displayed in the first color. After the second full rewriting process and the second full rewriting process, The given view by the partial drive; A second partial rewriting step of rewriting the expression, and after the second partial rewriting step is repeated the given number of times, the process returns to the first full rewriting step again, and the first partial rewriting step A first partial writing step of displaying, in the first color, a visual expression forming pixel that is a pixel forming the given visual expression, and a first part displaying the visual expression forming pixel in the second color An erasing step, a contour forming pixel forming a contour of the given visual representation among the visual representation forming pixels, and a background that is a pixel other than the visual representation forming pixel among pixels adjacent to the contour forming pixel A first afterimage erasing step for displaying an afterimage erasing area including a boundary pixel in the second color, and the second partial rewriting step displays the visual expression forming pixel in the second color. Second part writing And see step, displaying the visual representation form pixels in the first color includes a second partial erase process, displaying the afterimage erasing region in the first color, a second afterimage erasing step.

  According to the present invention, the DC balance can be achieved as a result by performing the second partial rewriting process for performing symmetrical display after the first partial rewriting process. By taking DC balance, an electrophoretic display device with high long-term reliability can be provided. The first partial rewriting step and the second partial rewriting step include a first afterimage erasing step and a second afterimage erasing step for erasing the outline of a given visual expression, respectively, and the afterimage can be erased, so that the visibility is improved. A good electrophoretic display device can be provided. The given visual expression may be any one of a character, a message, an image, a figure, a pattern, a symbol, or the like, or a combination thereof.

  The first color and the second color are two colors that are basic colors that can be displayed at least by a memory-type display means such as EPD. For example, in a two-particle microcapsule type electrophoresis system, the dispersion liquid is colorless and transparent, and the electrophoretic particles are white or black. This type of electrophoretic display unit is capable of displaying at least two colors, with white or black as the basic colors. At this time, black, which is one color of the migrating particles, may be assigned as the first color, and white may be assigned as the second color. Conversely, white may be assigned as the first color and black may be assigned as the second color.

  The symmetrical display means, for example, that the first partial rewriting process displays a black image with white as a background, and the second partial rewriting process displays the image with white as a background.

(2) In the driving method of the electrophoretic display device, the first full-surface rewriting step includes a first reverse display step and a first normal display step, and the second full-surface rewrite step is a second reverse display step. And a second normal rotation display step, wherein the first reverse display step is performed when the first color is displayed for all the pixels of the display unit based on the display of the first normal rotation display step. Displays the second color, and when the second color is displayed, performs a reverse display to display the first color, and the first normal display step is performed after the first reverse display step. The given area is displayed in the second color, and the second reverse display step performs the reverse display on all the pixels of the display unit based on the display of the second normal rotation display step, In the second normal display step, the given region is displayed after the second reverse display step. Serial may be displayed in the first color.

  According to the present invention, the first full surface rewriting step includes a first reverse display step and a first normal display step, and the second full surface rewrite step includes a second reverse display step and a second normal display step. Including. By including the step of performing reverse display, the first full surface rewrite step and the second full surface rewrite step can achieve DC balance in each step.

(3) In the driving method of the electrophoretic display device, in the first afterimage erasing step and the second afterimage erasing step, only the contour forming pixel and the background boundary pixel may be targeted as the afterimage erasing region.

  According to the present invention, the afterimage erasing area is the smallest area having a width of two adjacent pixels, and the number of pixels to be erased is also minimized. As a result, the time for driving the pulse in the first afterimage erasing step and the second afterimage erasing step is shortened, so that power consumption can be suppressed. The “two adjacent pixels” may include pixels adjacent in the oblique direction in addition to pixels adjacent in the horizontal and vertical directions in the display unit.

(4) In the driving method of the electrophoretic display device, the first partial rewriting step performs a region storing process for storing the afterimage erasing region, and the second partial rewriting step is stored by the region storing process. The second afterimage erasing step performed based on the afterimage erasing area may be included.

  According to the present invention, in the first partial rewriting process, even if, for example, the afterimage erasing area is changed or the number of repetitions of the first partial rewriting process is changed, the history of the same area stored by the area storing process is recorded. Accordingly, the second partial rewriting process can be correctly performed. Therefore, it is possible to provide an electrophoretic display device that can be displayed in various ways and is convenient for the user.

(5) In the driving method of the electrophoretic display device, the given number of times may be a plurality of times.

  According to the present invention, the first partial rewriting step and the second partial rewriting step of rewriting only a given visual expression that needs to be updated are repeated a plurality of times. Since the number of times of performing the first full-surface rewrite process and the second full-surface rewrite process for relatively driving all the pixels of the display portion is reduced, the processing efficiency can be increased and the power consumption can be reduced.

  The number of repetitions of the first partial rewriting step and the second partial rewriting step is in principle the same, but even if the DC balance is adjusted between the first partial rewriting step and the second partial rewriting step. Good.

(6) The present invention is an electrophoretic display device, in which an electrophoretic element including electrophoretic particles is sandwiched between a pair of substrates, and a display unit including pixels capable of displaying at least a first color and a second color And a control unit that controls the display unit, the control unit performing full-surface driving to apply a voltage to the electrophoretic element in all regions of the display unit, and a given one of the display units After the first full-surface rewrite control for displaying the region in the second color and the first full-surface rewrite control, a given visual perception is performed by partial driving in which a voltage is applied to the electrophoretic element within the given region. A first partial rewrite control for rewriting the expression and the first partial rewrite control are repeated a given number of times, and then the entire surface drive is performed to display the given region in the first color. 2 full rewrite control and the second full rewrite control After the second partial rewriting control, the second visual rewriting control is performed by rewriting the given visual expression by the partial driving, and the second partial rewriting control is repeated the given number of times. Returning to the rewrite control, in the first partial rewrite control, the first partial write control for displaying the visual expression forming pixel which is a pixel forming the given visual expression in the first color, and the visual expression forming pixel. Are displayed in the second color, out of the visual expression forming pixels, the contour forming pixels forming the contour of the given visual expression, and the pixels adjacent to the contour forming pixels In the second partial rewriting control, a first afterimage erasing control is performed, in which an afterimage erasing area including a background boundary pixel that is a pixel other than the visual expression forming pixel is displayed in the second color. A second partial writing control for displaying the visual expression forming pixels in the second color; a second partial erasing control for displaying the visual expression forming pixels in the first color; and the afterimage erasing area in the first color. The second afterimage erasing control displayed in step S3 is performed.

  According to the present invention, after the first partial rewriting control, the second partial rewriting control that performs symmetrical display is performed, and as a result, DC balance can be achieved. By taking DC balance, an electrophoretic display device with high long-term reliability can be provided. The first partial rewrite control and the second partial rewrite control include a first afterimage erasing control and a second afterimage erasing control for erasing the contour of a given visual expression, respectively. A good electrophoretic display device can be provided.

(7) In the electrophoretic display device, the control unit performs a first inversion display control and a first normal display control in the first entire rewrite control, and performs a second inversion in the second entire rewrite control. Display control and second normal display control are performed, and in the first reverse display control, the first color is displayed for all the pixels of the display unit based on the display of the first normal display control. In this case, the second color is displayed, and when the second color is displayed, the reverse display for displaying the first color is performed. In the first normal display control, the first reverse display control is performed. Later, the given area is displayed in the second color, and in the second reverse display control, the reverse display is performed for all the pixels of the display unit based on the display of the second normal display control. In the second forward rotation display control, After two inversion display control, the given area may be displayed in the first color.

  According to the present invention, the first full surface rewrite control includes a first reverse display control and a first normal display control, and the second full surface rewrite control includes the second reverse display control and the second normal display control. Including. By including control for performing reverse display, the first full-surface rewrite control and the second full-surface rewrite control can achieve DC balance in each control.

(8) In the electrophoretic display device, the control unit may use the afterimage erasing area including only the contour forming pixel and the background boundary pixel in the first afterimage erasing control and the second afterimage erasing control. Good.

  According to the present invention, the afterimage erasing area is the smallest area having a width of two adjacent pixels, and the number of pixels to be erased is also minimized. As a result, the time for driving pulses in the first afterimage erasing control and the second afterimage erasing control is shortened, so that power consumption can be suppressed.

(9) In the electrophoretic display device, the control unit includes a storage unit, and stores the afterimage erasing area in the storage unit in the first partial rewrite control, and stores the storage in the second partial rewrite control. The second afterimage erasing control may be performed based on the afterimage erasing area stored in the section.

  According to the present invention, in the first partial rewrite control, for example, even if the afterimage erasing area changes or the number of repetitions of the first partial rewrite control changes, based on the history of the same area stored in the storage unit. Thus, the second partial rewrite control can be performed correctly. Therefore, it is possible to provide an electrophoretic display device that can be displayed in various ways and is convenient for the user.

(10) The present invention may be an electronic apparatus including the electrophoretic display device.

  ADVANTAGE OF THE INVENTION According to this invention, the electronic device containing the electrophoretic display apparatus which erase | eliminates the afterimage along the outline of an image, DC balance can be provided. At this time, since there is no afterimage, the visibility of the electrophoretic display device is improved, and since the DC balance is achieved, the long-term reliability of the electrophoretic display device can be obtained.

(11) The present invention is an electronic timepiece including the electrophoretic display device, wherein the display unit performs time display including at least an hour digit and a minute digit, and the control unit performs the first partial rewrite control. In the second partial rewriting control, the minute digit of the time display may be the given visual expression.

  According to the present invention, the control unit performs the first partial rewrite control and the second partial rewrite control for the minute digit display of the electronic timepiece whose display changes every other minute. Therefore, it is possible to provide an electronic timepiece that performs time display with no afterimage and good visibility.

(12) In this electronic timepiece, the control unit may perform the first full rewrite control and the second full rewrite control with an interval of 12 hours.

  According to the present invention, the control unit performs the first full rewrite control and the first partial write control in the first 12 hours of the day. Then, the control unit performs the second full-surface rewrite control and the second partial write control in the remaining 12 hours of the day. Since the display mode is switched at exactly half a day, it is possible to perform display that does not give the user a sense of discomfort as an electronic timepiece while maintaining DC balance.

1 is a block diagram of an electrophoretic display device according to a first embodiment. FIG. 3 is a diagram illustrating a configuration example of a pixel of the electrophoretic display device according to the first embodiment. FIG. 3A illustrates a configuration example of an electrophoretic element. 3B and 3C are explanatory diagrams of the operation of the electrophoretic element. 5 is a flowchart of a method for driving the electrophoretic display device according to the first embodiment. FIGS. 5A to 5D are flowcharts of the subroutine of FIG. The wave form figure at the time of the 1st partial rewriting in 1st Embodiment. FIG. 7A to FIG. 7D are diagrams showing a display example at the time of first partial rewriting in the first embodiment, and cross-sectional views cut along the YY line. FIG. 8A to FIG. 8C are diagrams showing an afterimage erasing area in the first embodiment. FIGS. 9A to 9F are diagrams showing display examples at the time of rewriting the entire surface, and cross-sectional views taken along the line YY. The wave form figure at the time of the 2nd partial rewriting in 1st Embodiment. FIG. 11A to FIG. 11D are diagrams showing a display example at the time of second partial rewriting in the first embodiment, and cross-sectional views cut along the YY line. 12A is a diagram of a wrist watch that is an example of an electronic device, and FIG. 12B is a diagram of electronic paper that is an example of an electronic device. FIGS. 13A to 13P are diagrams showing display examples of an electronic timepiece according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the second and subsequent embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

1. First Embodiment A first embodiment of the present invention will be described with reference to FIGS.

1.1. Electrophoretic display device 1.1.1. Configuration of Electrophoretic Display Device FIG. 1 is a block diagram of an active matrix driving type electrophoretic display device 100 according to the present embodiment.

  The electrophoretic display device 100 includes a display unit 5 in which a plurality of pixels 40 are arranged. The control unit 6 controls the display unit 5. The control unit 6 includes a scanning line driving circuit 61, a data line driving circuit 62, a controller 63, and a common power supply modulation circuit 64.

  The scanning line driving circuit 61, the data line driving circuit 62, and the common power supply modulation circuit 64 are each connected to the controller 63. The controller 63 comprehensively controls these based on image signals and synchronization signals supplied from outside the figure. The controller 63 may include a storage unit 160. The storage unit 160 may be an SRAM, DRAM, or other memory, and may store image information to be displayed on the display unit 5. Further, the storage unit 160 repeats the positional information on the display unit 5 of the afterimage erasing area erased in the first afterimage erasing step S24 (see FIG. 5B) and the first partial rewriting step S2 (see FIG. 4). The number of times information may be stored. The stored information may be read by the controller 63, for example, and the second afterimage erasing step S64 (see FIG. 5D) or the like may be performed based on the information.

  In the display unit 5, a plurality of scanning lines 66 extending from the scanning line driving circuit 61 and a plurality of data lines 68 extending from the data line driving circuit 62 are formed, and the pixels 40 correspond to these intersecting positions. Is provided.

The scanning line driving circuit 61 is connected to each pixel 40 by _m scanning lines 66 (Y ₁ , Y ₂ ,..., Y _m ). The scanning line driving circuit 61 specifies the on-timing of the driving TFT 41 (see FIG. 2) provided in the pixel 40 by sequentially selecting the scanning lines 66 from the first row to the m-th row under the control of the controller 63. A selection signal is supplied.

The data line driving circuit 62 is connected to each pixel 40 by _n data lines 68 (X ₁ , X ₂ ,..., X _n ). The data line driving circuit 62 supplies an image signal defining 1-bit image data corresponding to each of the pixels 40 to the pixels 40 under the control of the controller 63. In the present embodiment, when defining pixel data “0”, a low-level image signal is supplied to the pixel 40, and when defining image data “1”, a high-level image signal is applied to the pixel 40. 40.

The display unit 5 also includes a low-potential power line 49 (Vss), a high-potential power line 50 (Vdd), a common electrode line 55 (Vcom), and a first control line 91 (S ₁ ) extending from the common power modulation circuit 64. ), A second control line 92 (S ₂ ) is provided, and each wiring is connected to the pixel 40. The common power supply modulation circuit 64 generates various signals to be supplied to each of the wirings according to the control of the controller 63, and performs electrical connection and disconnection (high impedance, Hi-Z) of these wirings.

1.1.2. Circuit Configuration of Pixel Part FIG. 2 is a circuit configuration diagram of the pixel 40 of FIG.

  The pixel 40 is provided with a driving TFT (Thin Film Transistor) 41, a latch circuit 70, and a switch circuit 80. The pixel 40 has an SRAM (Static Random Access Memory) type configuration in which an image signal is held as a potential by a latch circuit 70. In addition, the same number is attached | subjected to the same wiring as FIG. 1, and description is abbreviate | omitted. Further, the description of the common electrode wiring 55 common to all pixels is omitted.

  The driving TFT 41 is a pixel switching element made of an N-MOS transistor. The gate terminal of the driving TFT 41 is connected to the scanning line 66, the source terminal is connected to the data line 68, and the drain terminal is connected to the data input terminal of the latch circuit 70. The latch circuit 70 includes a transfer inverter 70t and a feedback inverter 70f. A power supply voltage is supplied to the inverters 70t and 70f from the low potential power supply line 49 (Vss) and the high potential power supply line 50 (Vdd).

  The switch circuit 80 includes transmission gates TG1 and TG2, and outputs a signal to the pixel electrode 35 (see FIGS. 3B and 3C) according to the level of the pixel data stored in the latch circuit 70. . Note that Va means a potential (signal) supplied to the pixel electrode of one pixel 40.

Image data "1" into latch circuit 70 (high-level image signal) is stored, the transmission gate TG1 is turned, switching circuit 80 supplies a potential S ₁ as Va. On the other hand, the image data "0" in the latch circuit 70 (the image signal of a low level) is stored, when the transmission gate TG2 is turned on, the switch circuit 80 supplies a potential S ₂ as Va. With such a circuit configuration, the control unit 6 can control the potential (signal) supplied to the pixel electrode of each pixel 40. The circuit configuration of the pixel 40 is an example, and is not limited to that shown in FIG.

1.1.3. Display Method The electrophoretic display device 100 of the present embodiment is a two-particle microcapsule type electrophoresis method. Assuming that the dispersion is colorless and transparent and the migrating particles are white or black, at least two colors can be displayed with two colors of white or black as basic colors. As described above, of the basic colors, the first color is black and the second color is white.

  FIG. 3A is a diagram showing a configuration of the electrophoretic element 32 of the present embodiment. The electrophoretic element 32 is sandwiched between an element substrate 30 and a counter substrate 31 (see FIGS. 3B and 3C). The electrophoretic element 32 is configured by arranging a plurality of microcapsules 20. The microcapsule 20 encloses, for example, a colorless and transparent dispersion, a plurality of white particles (electrophoretic particles) 27, and a plurality of black particles (electrophoretic particles) 26. In the present embodiment, for example, it is assumed that the white particles 27 are negatively charged and the black particles 26 are positively charged.

  FIG. 3B is a partial cross-sectional view of the display unit 5 of the electrophoretic display device 100. The element substrate 30 and the counter substrate 31 sandwich an electrophoretic element 32 in which the microcapsules 20 are arranged. A plurality of pixel electrodes 35 are formed on the electrophoretic element 32 side of the element substrate 30, and a potential can be supplied to each pixel 40 (Va, Vb).

  On the other hand, the counter substrate 31 is a transparent substrate, and an image is displayed on the counter substrate 31 side in the display unit 5. A planar common electrode 37 is formed on the counter substrate 31 on the electrophoretic element 32 side. The common electrode 37 is a transparent electrode. Unlike the pixel electrode 35, the common electrode 37 is an electrode common to all pixels, and is supplied with the potential Vcom.

  In FIG. 3B, the common electrode side potential Vcom is higher than the potential Va of the pixel electrode of the pixel 40A. At this time, the negatively charged white particles 27 are attracted to the common electrode 37 side, and the positively charged black particles 26 are attracted to the pixel electrode 35 side, so that the pixel 40A is visually recognized as displaying white. Of the pixels 40, the pixel to which the potential Va is supplied in the pixel electrode 35 is referred to as a pixel 40A, and the pixel to which the potential Vb is supplied is referred to as a pixel 40B.

  In FIG. 3C, the common electrode side potential Vcom is lower than the potential Va of the pixel electrode of the pixel 40A. At this time, on the contrary, the positively charged black particles 26 are attracted to the common electrode 37 side, and the negatively charged white particles 27 are attracted to the pixel electrode 35 side, so that it is visually recognized that the pixel 40A displays black. Is done. Note that the structure in FIG. 3C is similar to that in FIG.

1.2. Driving method of electrophoretic display device 1.2.1. Afterimage of Contour Part As a driving method of the electrophoretic display device, not only full-surface driving for drawing the entire display unit but also partial driving for drawing only a part of the display unit to be rewritten may be used. By reducing the number of pixels to which the voltage is applied, the response at the time of rewriting can be accelerated.

  However, when partial driving is performed, an electric field is generated in an oblique direction at a boundary portion with a pixel (background) that is not driven. When characters, figures, etc. displayed by partial driving are erased, the outlines of the letters, figures, etc. may be visually recognized as an afterimage due to the influence of an electric field generated in an oblique direction (see FIG. 7B). ). Therefore, when partial rewriting is performed by partial driving (partial rewriting), an operation (afterimage erasing) for erasing the afterimage of the contour portion is necessary.

  Note that when full-surface driving is performed, all pixels are driven, and an electric field is hardly generated in an oblique direction. Therefore, in the case of full-surface driving, afterimage erasing is not necessary (see FIGS. 9A and 9B).

1.2.2. The DC balance afterimage erasure is an auxiliary operation different from the display and erasure of characters, graphics and the like. In addition, the time during which the electric field is applied in the afterimage erasure is shorter than that in the display and erasure of characters, graphics, and the like. Therefore, conventionally, DC balance has not been considered for afterimage removal.

  However, an electric field is applied in a certain direction between the electrodes of the pixel to be subjected to afterimage erasure by the afterimage erasure. Since afterimage erasure is repeated with the display of characters, graphics, etc. itself, the asymmetry of the applied electric field increases as it continues to be used. Therefore, in order to ensure long-term reliability of the electrophoretic display device, it is necessary to balance DC including afterimage erasure.

  Therefore, a method for driving an electrophoretic display device capable of achieving DC balance including afterimage elimination will be described below.

1.2.3. Flowchart of Main Routine FIG. 4 is a flowchart of the driving method of the electrophoretic display device in the first embodiment.

1.2.3.1. First Whole Rewriting Step In the driving method of the electrophoretic display device according to this embodiment, first, the first whole rewriting step S1 is performed. In the first full-surface rewriting step S1, full-surface driving for drawing the entire display unit is performed. In the first full rewrite step S1, all of the given area of the display unit is displayed in the background color required by the first partial rewrite step S2.

  Here, the given region in the display unit refers to a region in which a given visual expression can be rewritten by partial driving in the first partial rewriting step S2 and the second partial rewriting step S6. A given visual representation is any of letters, messages, images, figures, patterns, symbols, etc., or a combination thereof.

  For example, it is assumed that characters A to Z are rewritten to a 6 pixel × 6 pixel region by partial driving, and the other regions of the display unit are rewritten only by full surface driving. At this time, the given area is an area of 6 pixels × 6 pixels, and the given visual expression is characters A to Z. In the first full-surface rewriting step S1, the entire display unit is drawn, and all of the 6 pixel × 6 pixel region is displayed in, for example, white (second color). Displaying the same area with a white background color is necessary to perform partial driving in the subsequent first partial rewriting step S2.

1.2.3.2. First Partial Rewriting Step In the first partial rewriting step S2, a given visual expression is rewritten by partial driving in the given region. The first partial rewriting step S2 includes a first afterimage erasing step S24 (see FIG. 5B) in which the afterimage erasing is performed. Then, in order to eliminate the DC imbalance (applied electric field asymmetry) occurring in the afterimage erasing, the second partial rewriting step S6 needs to be performed later.

  In the previous example, in the first partial rewriting step S2, the characters A to Z are displayed in black or are erased by partial driving in a 6 pixel × 6 pixel region. The afterimages along the outlines of the characters A to Z are also erased using white.

  The first partial rewriting step S2 may be repeated a given number of times (S3). In the previous example, if A to Z are displayed one by one in order, the first partial rewriting step S2 is repeated 26 times.

1.2.3.3. Second Full-surface Rewriting Step Also in the second full-surface rewriting step S5, full-surface driving for drawing the entire display unit is performed. Then, in the second entire rewriting step S5, the entire given area of the display unit is displayed in the background color required by the second partial rewriting step S6.

  In the previous example, in the second full-surface rewriting step S5, the entire display unit is drawn, and all the 6 pixel × 6 pixel region (given region) is displayed in black (first color). Displaying the same area with a black background color is necessary to perform partial driving in the subsequent second partial rewriting step S6. The second full rewrite step S5 has a meaning as a preparation for the subsequent second partial rewrite step S6.

1.2.3.4. Second Partial Rewriting Step In the second partial rewriting step S6, as in the first partial rewriting step S2, a given visual expression is rewritten by partial driving in the given area. The second partial rewriting step S6 includes a second afterimage erasing step S64 (see FIG. 5D) that performs a display opposite to the first afterimage erasing step S24 (see FIG. 5B). This eliminates the DC balance imbalance that occurs in the first partial rewriting step S2.

  For example, in an electrophoretic display device capable of displaying black as the first color and white as the second color, the first partial rewriting step S2 includes an operation of displaying an area including the contour portion (afterimage erasing area) in white. And At this time, the second partial rewriting step S6 includes an operation of displaying the afterimage display area in black. It is assumed that the direction of the applied electric field is the opposite between the case where white is displayed and the case where black is displayed, and the time during which the electric field is applied is the same.

  In the previous specific example, in the second partial rewriting step S6, the characters A to Z are displayed in white by the partial drive in the area of 6 pixels × 6 pixels, or these characters are erased. Then, the afterimages along the outlines of the characters A to Z are erased using black symmetrically with the first partial rewriting step S2.

  The second partial rewriting step S6 may be repeated a given number of times (S7). In the previous example, if A to Z are displayed one by one in order, the second partial rewriting step S6 is repeated 26 times. In the present embodiment, the number of repetitions is the same as the number of repetitions (S3) of the first partial rewriting step S2. If the first partial rewriting step S2 is repeated three times to display A to C, the second partial rewriting step S6 is also repeated three times to display A to C.

  After the second partial rewriting step S6, it may be determined whether or not there is a display end command of the electrophoretic display device (S8). When the display is continued, the process returns to S1 again (S8N), and when the display is ended, the control of the flowchart is also ended (S8Y). For example, in an electrophoretic display device used for an electronic timepiece, the display does not end, and the steps S1 to S7 are repeated again.

1.2.4. Subroutine flowchart 1.2.4.1. Full Rewrite Process FIGS. 5A and 5C are flowcharts showing subroutines of the first full rewrite process S1 and the second full rewrite process S5, respectively.

  In the first whole surface rewriting step S1 and the second whole surface rewriting step S5, full surface driving for drawing the entire display unit is performed. In the given area of the display unit, the first full-surface rewriting step S1 and the second full-surface rewriting step S5 perform symmetrical display. In the previous example, the entire area of 6 pixels × 6 pixels is displayed in white (second color) in the first full-surface rewrite step S1, and is displayed in black (first color) in the second full-surface rewrite step S5. If DC balance is established between the two processes of the first full-surface rewrite process S1 and the second full-surface rewrite process S5, a subroutine is not necessary for these processes.

  However, DC balance may not be achieved between the two processes of the first full rewrite process S1 and the second full rewrite process S5. For example, FIG. 13B is an example of the display unit 5 after the processing of the first full surface rewriting step S1, and FIG. 13J is an example of the display unit 5 after the processing of the second full surface rewriting step S5. Although the backgrounds are displayed in reverse to each other, since the display of the tens place of the minute digit is different, DC balance cannot be achieved between the processes of these steps. In such a case, the subroutines shown in FIGS. 5A and 5C are necessary.

1.2.4.2. Subroutine of First Full-Rewrite Process FIG. 5A is a flowchart showing a subroutine of the first full-rewrite process S1. In the present embodiment, the first full rewrite step S1 includes a first reverse display step S10 and a first normal display step S12.

  In the first full surface rewriting step S1, all the given areas of the display unit are displayed in the background color required by the subsequent first partial rewriting step S2 by the first normal rotation display step S12 (FIG. 9B). reference). In order to achieve DC balance with this display, a first reverse display step S10 for performing reverse display on the entire display unit is performed prior to the first normal display step S12 (see FIG. 9A). By these two display steps S10 and S12, DC balance is achieved in the first full-surface rewriting step S1. Further, the first partial rewriting step S2 is ready to rewrite a given visual expression by partial driving in the given area.

1.2.4.3. First Partial Rewriting Process Subroutine FIG. 5B is a flowchart showing a subroutine of the first partial rewriting process S2. In the present embodiment, the first partial rewriting step S2 includes a first partial writing step S20, a first partial erasing step S22, and a first afterimage erasing step S24.

  The first partial writing step S20 displays a given visual expression in a given area of the display unit. Using the previous example again, in the first partial writing step S20, when all of the 6 pixel × 6 pixel area (given area) is white (background color), it is black by partial driving, for example, A Display characters (given visual representation).

  The first partial erasing step S22 erases the given visual expression written in the first partial writing step S20. In the previous example, the first partial erasing step S22 performs erasing by displaying the letter A in white by partial driving. In the first partial erasing step S22, the same display is performed in the opposite color, so that a DC balance is achieved with the first partial writing step S20.

  In the first afterimage erasing step S24, an area (afterimage erasing area) including a contour of a given visual expression is erased. In the first afterimage erasing step S24, for example, the afterimage erasing area including the outline of the letter A (given visual expression) is displayed in white by partial driving to perform erasure. As will be described later, the afterimage erasing region includes at least a contour forming pixel that is a pixel that displays the contour of the letter A in black in the first partial writing step S20, and a background boundary pixel that is a white pixel adjacent to the contour forming pixel. (See R2 in FIG. 8A). At this time, DC balance imbalance occurs in the first afterimage erasing step S24.

1.2.4.4. Subroutine of Second Full Rewrite Process FIG. 5C is a flowchart showing a subroutine of the second full rewrite process S5. In the present embodiment, the second full rewrite step S5 includes a second reverse display step S50 and a second normal display step S52.

  The second reverse display step S50 and the second normal display step S52 correspond to the first reverse display step S10 and the first normal display step S12, respectively, and description thereof will be omitted. By these two display steps S50 and S52, DC balance is achieved in the second full-surface rewriting step S5. Also, the second partial rewriting step S6 is ready to rewrite a given visual expression.

1.2.4.5. Subroutine of Second Partial Rewriting Step FIG. 5D is a flowchart showing a subroutine of the second partial rewriting step S6. In the present embodiment, the second partial rewriting step S6 includes a second partial writing step S60, a second partial erasing step S62, and a second afterimage erasing step S64.

  The second partial writing step S60 corresponds to the first partial writing step S20 and displays a given visual expression in a given area of the display unit. If the previous example is used again, in the second partial writing step S60, when all of the 6 pixel × 6 pixel region (given region) is black (background color), it is white by partial driving, for example, A Display characters (given visual representation). Here, the given visual expression is the same as that displayed in the first partial writing step S20.

  The second partial erase step S62 corresponds to the first partial erase step S22 and erases the given visual expression written in the second partial write step S60. In the previous example, the second partial erasing step S62 performs erasing by displaying the letter A in black by partial driving. The second partial erasing step S62 has a DC balance with the second partial writing step S60.

  In the second afterimage erasing step S64, an area (afterimage erasing area) including a contour of a given visual expression is erased. In the second afterimage erasing step S64, the same afterimage erasing area as that in the first afterimage erasing step S24 is displayed in black so that the DC balance imbalance generated in the first afterimage erasing step S24 can be eliminated. .

  An electrophoretic display device that erases afterimages along the contour of an image while maintaining DC balance by following the driving method of the electrophoretic display device shown in the flowcharts of FIGS. 4 and 5A to 5D. A driving method is possible. For example, when visual expression is repeatedly displayed in a fixed cycle on the electrophoretic display device, the first full-surface rewrite step S1 and the first partial rewrite step S2, the second full-surface rewrite step S5, and the second partial rewrite step S6; By alternately assigning, it is possible to provide an electrophoretic display device with good visibility and long-term reliability.

  Next, an example of an electrophoretic display device that realizes this driving method will be described. The process numbers (S1 to S64) used in the following description and drawings correspond to the process numbers in the flowcharts of FIGS. 4 and 5A to 5D.

  In the present embodiment, it is assumed that the first color that can be displayed by the electrophoretic display device is black and the second color is white. Displaying pixels displaying black (first color) in white (second color) or displaying pixels displaying white in black is expressed as inversion.

1.3. Correspondence between flowchart and display in electrophoretic display device 1.3.1. First Full Rewrite Step A display example of the display unit 5 when the first full rewrite step S1 is performed by the electrophoretic display device 100 having the above-described configuration is shown in FIGS. 9A to 9D. I will explain. In the drawings cited in the following description including FIG. 9A to FIG. 9D, pixels indicated by diagonal lines in the display portion 5 indicate that the pixels are displayed in black. .

  First, in the first full-surface rewriting process S1, full-surface driving is performed in which all pixels are driven, and an electric field is hardly generated in an oblique direction, and there is no problem of an afterimage (see FIG. 7B) in the contour portion.

  Further, in the step of performing full-surface driving, DC display can be achieved by performing reverse display as shown in FIG. 9B after performing reverse display as shown in FIG. 9A. In the present embodiment, the DC balance is maintained by performing the first reverse display step S10 in the first full-surface rewriting step S1.

  Here, FIGS. 9C to 9D show display examples of the display unit 5 in the subroutines S10 and S12 of the first full-surface rewriting step S1. In FIG. 9C to FIG. 9D, a 6 pixel × 6 pixel region that can be partially driven is extracted from the display unit 5 and displayed. Moreover, the right figure of FIG.9 (C)-FIG.9 (D) is sectional drawing along the YY line of the left figure, respectively.

  FIG. 9C is a display example of the first reverse display step S10. FIG. 9D is a display example of the first normal display step S12. White, which is the background color of the subsequent first partial writing step S20, is displayed on all the pixels in the region.

1.3.2. First Partial Rewriting Step A display example of the display unit 5 when the first partial rewriting step S2 is performed by the electrophoretic display device 100 having the above configuration will be described below.

FIG. 6 is a waveform diagram at the time of the first partial rewriting in the present embodiment. S ₁ and S ₂ are signals from the common power supply modulation circuit 64 (see FIGS. 1 and 2). Va and Vb are signals supplied to the pixel electrodes 35 of the pixels 40A and 40B, respectively. Note that the pixel 40A and the pixel 40B are adjacent to each other (see FIGS. 3B and 3C). Also the circuit configuration of the pixel 40A and the pixel 40B are the same as FIG. 2, in accordance with the image data stored in the respective latch circuits, Va, and outputs the S ₁ or S ₂ as Vb. Vcom is a signal supplied from the common power supply modulation circuit 64 to the common electrode 37. Each of the signals Va, Vb, and Vcom can assume a high level (VH), a low level (VL), or a high impedance state (Hi-Z).

  As shown in FIG. 4, the first partial rewriting step S2 is repeated up to a predetermined number of times (S3). Therefore, “S2 (first loop)” in the corresponding step of FIG. 6 indicates that the first partial rewriting step S2 is performed first, and “S2 (second loop)” indicates that the first partial rewriting step S2 is performed. It means that it is done in the second iteration.

  In a section in which the corresponding process in FIG. 6 is indicated as S20 (first S2 loop), the first partial writing process S20 is performed. Since the potential of Va is VH, positively charged black particles 26 are attracted to the common electrode 37 side in the electrophoretic element 32 constituting the pixel 40A when Vcom is VL. The pixel 40A is displayed in black. On the other hand, in the same section, Vb is in a high impedance state, and the pixel 40B maintains a white display as a background color. The operation in the section in which the corresponding step in FIG. 6 is indicated as S20 (second S2 loop) is the same.

  In the section in which the corresponding step in FIG. 6 is indicated as S22, the first partial erasing step S22 is performed. Since the potential of Va is VL, the negatively charged white particles 27 are attracted to the common electrode 37 side in the electrophoretic element 32 that constitutes the pixel 40A when Vcom is VH. The pixel 40A is displayed in white. On the other hand, in the same section, Vb is in a high impedance state, and white display as the background color of the pixel 40B is maintained.

  At this time, the pixels displayed in black in the first partial writing step S20 including the pixel 40A are displayed in white in the first partial erasing step S22. In other words, the first partial erase step S22 can balance the DC with the first partial write step S20 performed before that. In the example of FIG. 6, the step S22 is performed for a longer time than the step S20, but each Vcom pulse width in the step S22 is shorter than the step S20. For this reason, the time average of the electric field applied between the electrodes in S20 and S22 is zero and the DC balance is achieved.

  In the section in which the corresponding step in FIG. 6 is indicated as S24, the first afterimage erasing step S24 is performed. Since the potential of Va is VL, the negatively charged white particles 27 are attracted to the common electrode 37 side in the electrophoretic element 32 that constitutes the pixel 40A when Vcom is VH. The pixel 40A is displayed in white. Further, since the potential of Vb is also VL, the adjacent pixel 40B is displayed in white. In the first afterimage erasing step S24, the DC balance is unbalanced.

  FIGS. 7A to 7D show a display example (left figure) and a cross-sectional view (right figure) of the display unit 5 corresponding to each step of FIG. In FIG. 7A to FIG. 7D, a 6 pixel × 6 pixel region that can be partially driven is extracted from the display unit 5 and displayed. 7A to 7D are cross-sectional views taken along line YY in the left diagram, and include pixels 40A and 40B.

  FIG. 7A corresponds to the first partial writing step S20 (first S2 loop) of FIG. The image P1 is written on the display unit 5, and the pixel 40A is one of the pixels (contour forming pixels) that forms the contour. The black 16 pixels (4 pixels × 4 pixels) forming the image P1 are visual expression forming pixels. The contour forming pixel is a part of the visual expression forming pixel. The pixel 40B forms one background of the image P1 and is one of the pixels (background boundary pixels) adjacent to the contour forming pixel. The potential of the pixel electrode 35A (Va) is VH, and the pixel 40A is displayed in black. On the other hand, the pixel electrode 35B (Vb) is in a high impedance state, and the pixel 40B maintains a white display as a background color.

  Here, FIG. 8C shows the contour forming pixel R3 and the background boundary pixel R4 in this example. The contour forming pixel R3 is 12 black pixels that form the contour of the image P1. One of them is the pixel 40A. The background boundary pixel R4 is 20 white pixels adjacent to the contour forming pixel R3. One of them is the pixel 40B. The background boundary pixel is adjacent to the contour forming pixel, but the adjacent boundary may include not only the horizontal and vertical directions but also an oblique direction. For example, not only the pixel 40B but also the pixel 40V, the pixel 40W, the pixel 40X, and the pixel 40Y may be included in the background boundary pixels.

  FIG. 7B corresponds to the first partial erase step S22 of FIG. 6 (first S2 loop). The pixels forming the image P1 written in the first partial writing step S20 are displayed in white. The potential of the pixel electrode 35A (Va) is VL, and the pixel 40A is white. At this time, an oblique electric field is generated between the contour forming pixel and the background boundary pixel in the high impedance state (Hi-Z) adjacent thereto, and an afterimage P2 is generated along the contour of the image P1. In this example, with a white background, a thin black afterimage P2 is visually recognized along the contour. Therefore, the next first afterimage erasing step S24 is required.

  FIG. 7C corresponds to the first afterimage erasing step S24 (first S2 loop) of FIG. In order to erase the afterimage P2 of the outline, the afterimage deletion area is displayed in the same white color as the background color. Here, the afterimage erasing area refers to an area including at least contour forming pixels and background boundary pixels.

  Here, FIG. 8A illustrates an afterimage erasing area in this example. R2 in the figure is the minimum afterimage erasing area composed of the contour forming pixel R3 and the background boundary pixel R4.

  Returning again to FIG. The afterimage P2 is erased by displaying the afterimage elimination region R2 shown in FIG. 8A in white. In the first afterimage erasing step S24, the potentials of the pixel electrodes 35A (Va) and 35B (Vb) of the pixels 40A and 40B are VL, and the electric field in the direction in which the negatively charged white particles 27 are attracted to the common electrode 37 side. Is applied. In order to achieve DC balance, it is necessary to perform an operation of applying a reverse electric field, that is, an operation of displaying the afterimage erasing region R2 in black as shown in FIG. 8B.

  The afterimage erasing area is not limited to R2 in FIG. 8A and may be a wider area (for three pixels or more). That is, the afterimage P2 may be more reliably erased by increasing the width toward the background side or the image side. However, as the width of the afterimage erasing area is smaller, the number of pixels to be partially driven is reduced and power consumption can be suppressed. Therefore, from the viewpoint of low power consumption, a minimum afterimage erasing area including a contour forming pixel and a background boundary pixel is preferable.

  FIG. 7D corresponds to the first partial writing step S20 (second S2 loop) of FIG. Even when the first partial rewriting step S2 is repeatedly performed and the image P11 is written in the display unit 5, the operations of the pixels 40A and 40B are the same as those in FIG.

1.3.3. Second Full-surface Rewriting Step Display examples of the display unit 5 when the second full-surface rewriting step S5 is performed by the electrophoretic display device 100 having the above-described configuration are shown in FIGS. 9A, 9B, and 9C. 9 (E) and FIG. 9 (F).

  First, in the second entire surface rewriting step S5, the entire surface driving in which all pixels are driven is performed, and an electric field is hardly generated in an oblique direction, and there is no problem of an afterimage (see FIG. 7B) of the contour portion.

  Further, in the step of performing full-surface driving, DC display can be achieved by performing reverse display as shown in FIG. 9B after performing reverse display as shown in FIG. 9A. In the present embodiment, the DC balance is maintained by performing the second reverse display step S50 in the second full-surface rewriting step S5.

  Here, display examples of the display unit 5 in the subroutines S50 and S52 of the second full-surface rewriting step S5 are shown in FIGS. 9 (E) to 9 (F). 9E to 9F, a 6 pixel × 6 pixel region in which partial driving can be performed is extracted from the display unit 5 and displayed. Moreover, the right figure of FIG.9 (E)-FIG.9 (F) is sectional drawing along the YY line | wire of the left figure, respectively.

  FIG. 9E is a display example of the second reverse display step S50. FIG. 9F is a display example of the second normal rotation display step S52. All the pixels in the region are displayed with black as the background color of the subsequent second partial writing step S60.

1.3.4. Second Partial Rewriting Step A display example of the display unit 5 when the second partial rewriting step S6 is performed by the electrophoretic display device 100 will be described below.

  FIG. 10 shows a waveform diagram at the time of second partial rewriting in the present embodiment. The symbols and the like in FIG. 10 are the same as those in FIG. Also, the number of loops in FIG. 10 is the same as in FIG.

  In the section in which the corresponding process in FIG. 10 is indicated as S60 (S6 first loop), the second partial writing process S60 is performed. Since the potential of Va is VL, the negatively charged white particles 27 are attracted to the common electrode 37 side in the electrophoretic element 32 that constitutes the pixel 40A when Vcom is VH. The pixel 40A is displayed in white. On the other hand, in the same section, Vb is in a high impedance state, and the display of black as the background color of the pixel 40B is maintained. The operation in the section in which the corresponding step in FIG. 10 is indicated as S60 (second S6 loop) is the same.

  In the section in which the corresponding step in FIG. 10 is indicated as S62, the second partial erasing step S62 is performed. Since the potential of Va is VH, positively charged black particles 26 are attracted to the common electrode 37 side in the electrophoretic element 32 constituting the pixel 40A when Vcom is VL. The pixel 40A is displayed in black. On the other hand, in the same section, Vb is in a high impedance state, and the pixel 40B maintains a black display as a background color.

  At this time, the pixels displayed in white in the second partial writing step S60 including the pixel 40A are displayed in black in the second partial erasing step S62. That is, the second partial erasing step S62 can balance the DC with the second partial writing step S60 performed before that.

  In the section in which the corresponding step in FIG. 10 is indicated as S64, the second afterimage erasing step S64 is performed. Since the potential of Va is VH, positively charged black particles 26 are attracted to the common electrode 37 side in the electrophoretic element 32 constituting the pixel 40A when Vcom is VL. The pixel 40A is displayed in black. Further, since the potential of Vb is also VH, the adjacent pixel 40B is displayed in black. In the operation in this section, the afterimage erasing area displayed in white in the section indicated by S24 in FIG. 6 is displayed in black, and the DC balance is maintained with the afterimage erasing step S24 in FIG.

  11A to 11D show a display example (left diagram) of the display unit 5 corresponding to FIG. 10 and cross-sectional views (right diagram) of the pixel 40A and the pixel 40B in the display unit 5. FIG. Is. Note that the display method in FIGS. 11A to 11D is the same as that in FIG.

  FIG. 11A corresponds to the second partial writing step S60 (first S6 loop) of FIG. The image P1 is written in the display unit 5, the potential of the pixel electrode 35A (Va) is VL, and the pixel 40A is displayed in white. On the other hand, the pixel electrode 35B (Vb) is in a high impedance state, and the pixel 40B maintains a black display as the background color.

  FIG. 11B corresponds to the second partial erasing step S62 (first S6 loop) of FIG. The pixels forming the image P1 written in the second partial writing step S60 are displayed in black. The potential of the pixel electrode 35A (Va) is VH, and the pixel 40A is black. At this time, an oblique electric field is generated between the contour forming pixel and the background boundary pixel in the high impedance state (Hi-Z) adjacent thereto, and an afterimage P2 is generated along the contour of the image P1. In this example, a thin white afterimage P2 is visually recognized along the outline with black as a background. Therefore, the next second afterimage erasing step S64 is necessary. Note that in FIG. 11B, P2 is indicated by a black line for convenience of description.

  FIG. 11C corresponds to the second afterimage erasing step S64 (first S6 loop) of FIG. The potentials of the pixel electrodes 35A (Va) and 35B (Vb) of the pixels 40A and 40B are VH, and an electric field in a direction in which the negatively charged black particles 27 are attracted toward the common electrode 37 is applied. In this way, in the second afterimage erasing step S64, the afterimage erasing area is displayed in black, which is the same as the background color, in order to erase the outline afterimage P2. Since the display is in black, which is the same as the background color, this operation is not visually recognized by the user.

  Here, this afterimage erasing area is the same afterimage erasing area R2 (see FIG. 8A) as in the first afterimage erasing step S24 (first S2 loop) of FIG. In this step, since an operation for displaying the afterimage erasing region R2 in black, that is, an operation for applying an electric field in the reverse direction, is performed, DC balance is achieved with the afterimage erasing step S24 of FIG.

  FIG. 11D corresponds to the second partial writing step S60 (second S6 loop) of FIG. Even when the second partial rewriting step S6 is repeatedly performed and the image P11 is written on the display unit 5, the operations of the pixels 40A and 40B are the same as those in FIG.

  As described above, the electrophoretic display device 100 according to the present embodiment has an image while maintaining DC balance by the driving method of the electrophoretic display device shown in the flowcharts of FIGS. 4 and 5A to 5D. It is possible to erase the afterimage along the outline of the image. At this time, without providing a correction process only for achieving DC balance, the normal display (first full rewrite process S1, first partial rewrite process S2) is followed by reverse display (second full rewrite process S5, first full rewrite process S5, second full rewrite process S5, second partial rewrite process S5, The DC balance can be achieved only by performing the two-part rewriting step S6). An electrophoretic display device with excellent long-term reliability can be provided by balancing DC.

2. Electronic Device A second embodiment of the present invention will be described with reference to FIGS. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected, description is abbreviate | omitted, and a different part is demonstrated.

  The electrophoretic display device 100 can be applied to various electronic devices.

  For example, FIG. 12A is a front view of a wrist watch 1000 that is one of electronic devices. The wristwatch 1000 includes a watch case 1002 and a pair of bands 1003 connected to the watch case 1002. A display unit 1004 including the electrophoretic display device 100 is provided in front of the watch case 1002, and the display unit 1004 displays a display 1005 including a time display. Two operation buttons 1011 and 1012 are provided on the side of the watch case. Note that various display forms such as time, calendar, and alarm may be selected as the display 1005 by the operation buttons 1011 and 1012.

  For example, FIG. 12B is a perspective view of an electronic paper 1100 that is one of the electronic devices. The electronic paper 1100 is flexible and includes a display area 1101 including the electrophoretic display device 100 and a main body 1102.

  The electronic apparatus including the electrophoretic display device 100 has no afterimage, so that the visibility of the electrophoretic display device is improved and the DC balance is achieved, so that long-term reliability of the electrophoretic display device is obtained.

2.1. Here, an embodiment of an electronic timepiece including a wrist watch 1000 will be described as a second embodiment.

  FIGS. 13A to 13P show display examples of the display unit 5 of the electronic timepiece according to this embodiment. In FIG. 13A to FIG. 13P, only the time display portion is extracted from the display unit 5. An area 51 indicates an area where partial driving can be performed. In the embodiment shown in FIGS. 13A to 13P, the area 51 corresponds to the first digit of the minute digit of the time display. For example, the area 51 may include the tenth digit of the minute digit, The entire time display may be the area 51.

  In the enlarged view (right view) of the region 51 in FIG. 13A to FIG. 13P, a gray portion indicates a pixel that is not subject to partial driving. That is, the pixels displayed in black or white in the enlarged view of the region 51 are partially driven. In addition, the process number attached | subjected to FIG. 13 (A)-FIG. 13 (P) respond | corresponds to the process number of the flowchart of FIG. 4, FIG. 5 (A)-FIG.

  In FIG. 13A, the first inversion display step S10 is performed, and inversion display is performed on the entire surface of the display portion 5 by driving the entire surface. This is for achieving DC balance with the subsequent FIG.

  In FIG. 13B, the first normal display step S12 is performed, and the region 51 is displayed in white by full-surface driving. White is the background color of the subsequent partial drive display (FIGS. 13C to 13H).

  FIG. 13C shows that the time is 12:00. The first partial writing step S20 is performed, and 0 is displayed in black in the region 51 as a single digit.

  FIG. 13D shows that the first partial erasing step S22 is performed before the time changes from 12:00 to 12:01, and 0 displayed in black in the region 51 is erased.

  FIG. 13E shows that the first afterimage erasing step S24 is performed and the afterimage of the 0 contour portion displayed in black in the region 51 is erased. At this time, an area storing process for storing information of an afterimage erasing area (area displayed in white in the right diagram in FIG. 13E) is performed, and information is stored in, for example, the storage unit 160 (see FIG. 1). And

  Thereafter, the first digit of the minute digit changes to 1, 2, 3,..., And the same steps as those in FIGS. This corresponds to repeating the first partial rewriting step S2 10 times as a given number of times in S3 of FIG. During this time, the afterimage erasing areas 1, 2, 3,..., 9 are stored in the storage unit 160. 13 (F) to 13 (H) are cases where the first digit of the minute digit is 9 in FIGS. 13 (C) to 13 (E), respectively, and description thereof is omitted.

  In FIG. 13I, the second inversion display step S50 is performed, and inversion display is performed on the entire surface of the display unit 5 by full-surface driving. This is to achieve DC balance with the subsequent FIG. Since ten minutes have passed, the tenth digit of the minute digit changes from 0 to 1.

  In FIG. 13J, the second normal display step S52 is performed, and the region 51 is displayed in black by the entire surface driving. Black is the background color of the subsequent partial drive display (FIGS. 13K to 13P). With black as the background color, the time display and separator (:) are displayed in white characters.

  FIG. 13K shows that the time is 12:10. The second partial writing step S60 is performed, and 0 is displayed in white in the area 51 as a single digit.

  FIG. 13L shows that the second partial erasing step S62 is performed before the time changes from 12:10 to 12:11, and 0 displayed in white in the region 51 is erased.

  FIG. 13M shows that the second afterimage erasing step S64 is performed and the afterimage of the 0 contour portion displayed in white in the region 51 is erased. At this time, the afterimage erasing area (the area displayed in black in the right diagram in FIG. 13M) is specified based on, for example, information on the afterimage erasing area from the storage unit 160 (see FIG. 1). For this reason, the afterimage erasing areas in the first partial rewriting process (FIGS. 13C to 13H) and the second partial rewriting process (FIGS. 13K to 13P) are accurately matched. DC balance can be achieved.

  Thereafter, the first digit of the minute digit changes to 1, 2, 3,..., And the same steps as those in FIGS. This corresponds to repeating the second partial rewriting step S6 10 times as a given number of times in S7 of FIG. 13 (N) to 13 (P) are cases where the first digit of the minute digit is 9 in FIGS. 13 (K) to 13 (M), respectively, and thus description thereof is omitted.

  As described above, the electronic timepiece of the present embodiment does not provide a correction process only for achieving DC balance, and reverse display (FIG. 13 (C) to FIG. 13 (H)) is followed by reverse display ( 13 (K) to FIG. 13 (P)), a DC balance can be achieved, and an electronic timepiece with high long-term reliability can be provided. In the present embodiment, after the process of FIG. 13 (P), the tenth digit of the minute digit changes to 2, and the process returns to the first reverse display step S10 (FIG. 13 (A)), which has been described above. Repeat the process.

  In the example of the electronic timepiece of FIGS. 13A to 13P, the white background and the black background are switched every 10 minutes, but the background may be switched every 12 hours, for example. In other words, the first full rewrite control (FIGS. 13A and 13B) and the second full rewrite control (FIGS. 13I and 13J) are performed with an interval of 12 hours. May be. Reducing the number of times of the first or second full-surface rewrite control that needs to rewrite the entire surface is efficient for the control unit (see FIG. 1), for example.

  For example, it is possible to display a white background from 6:00 am to 5:59 pm (daytime) and display a black background from 6:00 pm to 5:59 am (nighttime). is there. At this time, since the background color corresponding to the brightness of the environment is selected, even if the background color changes, there is an effect that does not give the user a sense of incongruity. The time for changing the background is not limited to 12 hours, but may be 6 hours, 4 hours, 2 hours, 1 hour, or the like.

  13A to 13P, FIG. 13A and FIG. 13B, FIG. 13C and FIG. 13D, FIG. 13F, and FIG. 13 (G), FIG. 13 (I) and FIG. 13 (J), FIG. 13 (K) and FIG. 13 (L), FIG. 13 (N) and FIG. 13 (O), FIG. 13 (E) and FIG. M), and the DC balance is taken in each of the pairs of FIG. 13 (H) and FIG. 13 (P).

3. Others In the above-described embodiment, the electrophoretic display device is not limited to one that performs black and white two-particle electrophoresis using black particles and white particles, and may perform one-particle electrophoresis such as blue and white, Also, combinations other than black and white may be used.

  The driving method described above may be applied not only to the electrophoretic display device but also to a memory-type display unit. For example, ECD (Electrochromic Display = electrochromic display), ferroelectric liquid crystal display, cholesteric liquid crystal display, and the like.

  Furthermore, the electronic timepiece of the above embodiment is not limited to a wristwatch, and can be widely applied to devices having a clock function such as a table clock, a wall clock, and a pocket watch.

  The present invention is not limited to these exemplifications, and 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 5 ... Display part, 6 ... Control part, 20 ... Microcapsule, 26 ... Black particle, 27 ... White particle, 30 ... Element substrate, 31 ... Opposite substrate, 32 ... Electrophoretic element, 35 ... Pixel electrode, 35A ... Pixel electrode , 35B ... pixel electrode, 37 ... common electrode, 40 ... pixel, 40A ... pixel, 40B ... pixel, 40V ... pixel, 40W ... pixel, 40X ... pixel, 40Y ... pixel, 41 ... driving TFT (Thin Film Transistor), 49 ... Low potential power line (Vss), 50 ... High potential power line (Vdd), 51 ... Area, 55 ... Common electrode wiring (Vcom), 61 ... Scanning line driving circuit, 62 ... Data line driving circuit, 63 ... Controller , 64 ... common power supply modulation circuit, 66 ... scanning line, 68 ... data line, 70 ... latch circuit, 80 ... switch circuit, 91 ... first control line (S ₁ ), 92 ... second control line (S ₂₎ ), 100 ... Electric Electrophoresis display device, 160 ... storage unit, 1000 ... wristwatch, 1002 ... watch case, 1003 ... band, 1004 ... display unit, 1005 ... display, 1011 ... operation button, 1012 ... operation button, 1100 ... electronic paper, 1101 ... display area 1102 ... Main body, P1 ... Image (visual expression forming pixel), P2 ... Afterimage, P11 ... Image, R2 ... Afterimage erasing area, R3 ... Outline forming pixel, R4 ... Background boundary pixel, S1 ... First full rewrite step, S2 ... 1st partial rewriting process, S5 ... 2nd full surface rewriting process, S6 ... 2nd partial rewriting process, S10 ... 1st reverse display process, S12 ... 1st normal rotation display process, S20 ... 1st partial writing process, S22 ... First partial erasing step, S24 ... first afterimage erasing step, S50 ... second reverse display step, S52 ... second forward display step, S60 ... second partial writing Step, S62 ... second partial deletion step, S64 ... second afterimage erasing step

Claims (12)

A method for driving an electrophoretic display device including an electrophoretic element including electrophoretic particles between a pair of substrates and including a display unit including pixels capable of displaying at least a first color and a second color,
A first full-surface rewriting step of performing full-surface driving for applying a voltage to the electrophoretic element in all regions of the display unit, and displaying a given region of the display unit in the second color;
A first partial rewriting step of performing rewriting of a given visual expression by partial driving by applying a voltage to the electrophoretic element within the given region after the first full rewriting step;
After the first partial rewriting step is repeated a given number of times, performing the whole surface driving and displaying the given region in the first color;
A second partial rewriting step of rewriting the given visual representation by the partial driving after the second full surface rewriting step,
After the second partial rewriting process is repeated the given number of times, the process returns to the first full rewriting process again,
The first partial rewriting step includes
A first partial writing step of displaying, in the first color, visual representation forming pixels that are pixels forming the given visual representation;
A first partial erasing step of displaying the visual representation forming pixels in the second color;
A contour forming pixel that forms a contour of the given visual representation among the visual representation forming pixels, and a background boundary pixel that is a pixel other than the visual representation forming pixels among pixels adjacent to the contour forming pixels; Including a first afterimage erasing step for displaying an afterimage erasing region including the second color,
The second partial rewriting step includes
A second partial writing step of displaying the visual expression forming pixels in the second color;
A second partial erasing step of displaying the visual representation forming pixel in the first color;
And a second afterimage erasing step of displaying the afterimage erasing region in the first color. The method for driving an electrophoretic display device according to claim 1,
The first entire surface rewriting step includes
Including a first reverse display step and a first normal display step;
The second whole surface rewriting step includes
Including a second reverse display step and a second normal display step;
The first reverse display step includes
For all the pixels of the display unit, when the first color is displayed based on the display in the first normal rotation display step, the second color is displayed, and when the second color is displayed. Performs a reverse display to display the first color,
The first normal rotation display step includes
After the first reverse display step, the given area is displayed in the second color;
The second reverse display step includes
For all the pixels of the display unit, based on the display of the second normal rotation display step, to perform the reverse display,
The second normal rotation display step includes
A method for driving an electrophoretic display device, wherein the given region is displayed in the first color after the second inversion display step. The method for driving an electrophoretic display device according to claim 1,
In the first afterimage erasing step and the second afterimage erasing step,
A method for driving an electrophoretic display device, which targets only the contour forming pixels and the background boundary pixels as the afterimage erasing region. In the driving method of the electrophoretic display device according to claim 1,
The first partial rewriting step includes
An area storing process for storing the afterimage erasing area is performed,
The second partial rewriting step includes
A method for driving an electrophoretic display device, comprising the second afterimage erasing step performed based on the afterimage erasing region stored in the region storing process. In the driving method of the electrophoretic display device according to claim 1,
The method for driving an electrophoretic display device, wherein the given number of times is a plurality of times. An electrophoretic display device comprising:
A display unit including an electrophoretic element including electrophoretic particles between a pair of substrates and a pixel that can display at least a first color and a second color;
A control unit for controlling the display unit,
The controller is
A first full-surface rewrite control for performing full-surface driving to apply a voltage to the electrophoretic element in all regions of the display unit, and displaying a given region of the display unit in the second color;
A first partial rewriting control for rewriting a given visual expression by partial driving by applying a voltage to the electrophoretic element within the given region after the first full rewriting control;
After the first partial rewrite control is repeated a given number of times, the second full rewrite control for performing the full drive and displaying the given area in the first color;
Performing the second partial rewriting control for rewriting the given visual expression by the partial driving after the second full rewriting control;
After the second partial rewrite control is repeated the given number of times, the process returns to the first full rewrite control again,
In the first partial rewrite control,
A first partial writing control for displaying a visual expression forming pixel that is a pixel forming the given visual expression in the first color;
A first partial erasure control for displaying the visual expression forming pixel in the second color;
A contour forming pixel that forms a contour of the given visual representation among the visual representation forming pixels, and a background boundary pixel that is a pixel other than the visual representation forming pixels among pixels adjacent to the contour forming pixels; And a first afterimage erasing control for displaying an afterimage erasing area including the second color,
In the second partial rewrite control,
A second partial writing control for displaying the visual expression forming pixel in the second color;
A second partial erasure control for displaying the visual expression forming pixel in the first color;
An electrophoretic display device that performs second afterimage erasure control for displaying the afterimage erasure region in the first color. The electrophoretic display device according to claim 6.
The controller is
In the first overall rewrite control,
Performing the first reverse display control and the first normal display control;
In the second overall rewrite control,
Perform the second reverse display control and the second normal display control;
In the first reverse display control,
For all the pixels of the display unit, when the first color is displayed based on the display of the first normal display control, the second color is displayed, and when the second color is displayed. Performs a reverse display to display the first color,
In the first normal display control,
After the first reverse display control, the given area is displayed in the second color,
In the second reverse display control,
For all the pixels of the display unit, based on the display of the second normal rotation display control, the reverse display,
In the second normal rotation display control,
An electrophoretic display device that displays the given region in the first color after the second reverse display control. The electrophoretic display device according to any one of claims 6 to 7,
The controller is
In the first afterimage erasing control and the second afterimage erasing control,
An electrophoretic display device using the afterimage erasing region including only the contour forming pixels and the background boundary pixels. The electrophoretic display device according to any one of claims 6 to 8,
The controller is
Including a storage unit,
In the first partial rewrite control,
Storing the afterimage erasing area in the storage unit;
In the second partial rewrite control,
An electrophoretic display device that performs the second afterimage erasing control based on the afterimage erasing area stored in the storage unit.   An electronic apparatus comprising the electrophoretic display device according to claim 6. An electronic timepiece including the electrophoretic display device according to claim 6,
The display unit
At least display the time including the hour and minute digits,
The controller is
In the first partial rewriting control and the second partial rewriting control, an electronic timepiece in which the minute digit of the time display is the given visual expression. The electronic timepiece according to claim 11,
The controller is
An electronic timepiece in which the first full rewrite control and the second full rewrite control are performed with an interval of 12 hours.

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