JP5045976B2 - Electrophoretic display device and driving method thereof - Google Patents

Description

  The present invention relates to an electrophoretic display device and a driving method thereof, and more particularly to an electrophoretic display device and a driving method thereof that can perform good display without causing afterimages and image sticking in a display.

In electronic display devices, when reading electronic books, electronic newspapers, and the like with eyes, there is an electronic paper display as a display that enables reading without causing stress on the eyes, and the development thereof has been intensively performed. Requirements for this electronic paper display include thinness, light weight, difficulty in cracking, and ease of viewing as a printing level.
As a display device that satisfies these requirements, there is a reflective display that does not use a backlight and consumes less power.

An example of a reflective display that does not use a deflecting plate is an electrophoretic display device (hereinafter also referred to as an EPD (Electrophorphoretic Display)). Although there are several types of EPDs, EPD using a microcapsule type electrophoretic element (also referred to as an electrophoretic element) will be described below.
FIG. 14 is a cross-sectional view of m columns of a matrix arrangement of m rows and n columns of a monochrome microcapsule electrophoretic element. As shown in FIG. 14, each of the microcapsule type electrophoretic elements has a laminated structure in which a TFT glass substrate 102, an electrophoretic film 110, and a PET (Poly Ethylene Terephthalete) counter substrate 120 are laminated in this order. For example, m rows of microcapsule type electrophoretic elements 100-m1, 100-m2, and 100-m3 are formed. These electrophoretic elements constitute an electrophoretic display panel.

The TFT glass substrate 102 includes one TFT 104-m1, 104-m2, and 104-m3 corresponding to the electrophoretic elements 100-m1, 100-m2, and 100-m3, and the TFTs 104-m1, 104-m2, and 104. Pixel electrodes 106-m1, 106-m2, and 106-m3 connected to -m3 are provided. Storage electrodes 108-m1, 108-m2, and 108-m3 are also provided for each electrophoretic element.
In the electrophoretic film 110, about 40 μm microcapsules 114 are spread in a polymer binder 112. Each of the microcapsules 114 is conventionally smaller by a certain value than the size of the pixel electrode of the active matrix microcapsule electrophoretic display device. Inside the microcapsule 114, a solvent 116 is injected, into the solvent 116, a nano-sized negatively charged white pigment (white particles, TiO) 117 and a positively charged black color. An infinite number of pigments (black particles, carbon) 118 are suspended.
The PET counter substrate 120 is formed by attaching a single counter electrode 122 facing the pixel electrodes 106-m1, 106-m2, and 106-m3 of the TFT glass substrate 102 to a transparent plastic substrate 124.
Therefore, each of the microcapsule type electrophoretic elements 100-m1, 100-m2, and 100-m3 includes TFTs 104-m1, 100-m2, and 100-m3 corresponding to each pixel, and pixel electrodes 106-m1, 106-m2, and 106, respectively. -m3, formed by corresponding parts of the microcapsule 114 and the counter electrode 122.

FIG. 15 schematically shows a matrix arrangement of microcapsule electrophoretic elements in an active matrix microcapsule electrophoretic display device (also referred to as an electrophoretic display device) on a plane. Among the components in FIG. 15, the same components as those in FIG. 14 are denoted by the same reference numerals.
In FIG. 15, data lines Dn are electrophoretic elements 100-mn (m = 1, 2,..., M, n = 1, 2) in a matrix arrangement of the active matrix microcapsule electrophoretic display device shown in FIG. ,..., N) as a representative line for supplying a display data signal to each horizontal electrophoretic element 100-mi (i = 1, 2,..., N). Further, in FIG. 15, the scanning line Gm represents a horizontal electrophoretic element group 100-m1 of the electrophoretic elements 100-mn in the matrix array of the active matrix microcapsule electrophoretic display device shown in FIG. 100-m 2,..., 100-mN is a line representative of lines for supplying a scanning voltage for one scanning line period.

FIG. 16 shows a drive circuit 140 of an active matrix microcapsule type electrophoretic display device, and this drive circuit 140 is a group of electrophoretic elements (100-m1, 100) in the horizontal direction among the electrophoretic elements arranged in a matrix. -m2,..., 100-mN) for each scanning line 142 for sequentially supplying a scanning voltage for one scanning line period, and each electrophoretic element 100-mi in the horizontal direction among the electrophoretic elements in a matrix arrangement. It is a figure which shows the data driver 144 which supplies a display data signal sequentially via the line Dn.
FIG. 17 is a diagram showing a data signal generation circuit 145 for each data line Dn constituting the data driver 144. The selection signal generation circuit 146 that generates a selection signal in response to screen data and the output from the selection signal generation circuit 146 are shown. The voltage selection circuit 147 outputs a voltage corresponding to the selection signal to the data line Dn.

  In the active matrix microcapsule electrophoretic display device configured as described above, a voltage is applied to the pixel electrode 106-mn of the microcapsule electrophoretic element 100-mn as follows, and the active matrix microcapsule is displayed. An image corresponding to the screen data input on the screen of the electrophoretic display device is displayed.

  That is, when an electrophoretic element corresponding to a certain pixel in the screen of the active matrix microcapsule electrophoretic display device is to be displayed in a white display state (hereinafter also referred to as W), the pixel of the electrophoretic element 100-mn A negative voltage, for example, a voltage of −15 volts, is applied to the electrode 106-mn, for example, the data line connected to the pixel electrode 106-mn of the data driver 144, for example, the data line Dn between the data driver 144 and the required number of frames. Output. This will be described with reference to FIG. 17. The selection signal generation circuit 146 that receives screen data outputs a negative voltage during the pixel period on a selection line corresponding to the pixel, for example, the selection line 152-n. As a result, the pMOS of the voltage selection circuit 147, for example, the pMOS 154-n is turned on and outputs a voltage of -15 volts to the data line Dn.

  When an electrophoretic element corresponding to a certain pixel in the screen of the active matrix microcapsule electrophoretic display device is to be displayed in a black display state (hereinafter also referred to as B), the pixel of the electrophoretic element 100-mn is displayed. A positive voltage, for example, a voltage of +15 volts, is output to the electrode 106-mn for a required number of frames from the data driver 144 to the data line connected to the pixel electrode 106-mn of the data driver 144, for example, the data line Dn. To do. This will be described with reference to FIG. 17. The selection signal generation circuit 146 that receives screen data outputs a negative voltage during the pixel period on a selection line corresponding to the pixel, for example, the selection line 156-n. As a result, the pMOS of the voltage selection circuit 147, for example, the pMOS 158-n is turned on and outputs a voltage of +15 volts to the data line Dn.

  Since the active matrix microcapsule type electrophoretic display device that performs monochrome display in this manner has memory characteristics, when switching the pixel display from W → B or B → W, the above-described case may be considered. Although it is necessary to apply the same voltage to the pixel electrode of the electrophoretic element corresponding to the pixel to be switched, when the pixel is displayed in W → W or B → B, the electrophoretic element has memory characteristics. Therefore, basically, it is not necessary to apply a voltage to the pixel.

An example analyzed by the present inventor for such an active matrix microcapsule electrophoretic display device will be described as follows.
As described above, the electrophoretic film has a positive voltage applied to the pixel electrode in the transition from W to B, a negative voltage applied to the pixel electrode in the transition from B to W, and W → W, B → In B, it is necessary to apply a voltage of 0 volts.

Further, in driving an active matrix microcapsule electrophoretic display device, unlike an active matrix display device such as a liquid crystal display, the screen cannot be rewritten in one frame with 1/60 Hz = 16.6 ms as one frame.
This is because the microcapsule type electrophoretic element is closed in a microcapsule containing a solvent, and the responsiveness of the particle is poor, and rewriting of the screen is completed unless voltage is continuously applied for a period of multiple frames. Because it does not.
For this reason, in an active matrix microcapsule electrophoretic display device, generally, as shown in FIG. 18, a constant negative voltage is applied in the case of rewriting from B (black) to W (white) during a period of a plurality of frames. Further, in the case of rewriting from W (white) to B (black), PWM driving (PWM is an abbreviation for Pulse Width Modulation) in which a constant positive voltage is continuously applied is performed.

  In order to realize the drive shown in FIG. 18, in the conventional example, the previous screen is stored in a frame buffer constituted by SRAM, and the difference from the next screen is obtained, so that B → W and W → B. It is considered that a corresponding voltage is applied during a period of a plurality of frames. As a method of applying the voltage, a ternary (+ V, 0 volt, −V) driver is used for the H-Driver (scan driver), and the Vcom voltage is 0 volt. The pixels for which the rewriting of the pixels in each frame from B → W and W → B is performed at the corresponding time of the frame.

Further analysis of the above-described conventional active matrix type microcapsule type electrophoretic display device by the present inventor has revealed the following technical problems.
Although the microcapsule type electrophoretic element has a memory property, when the microcapsule type electrophoretic element is driven in the driving mode shown in FIG. 19, the microcapsule type electrophoretic element is driven without applying a voltage to the pixel electrode. It was observed that there was a decrease in white brightness and an increase in black brightness. This is considered to be due to the influence of the gate line and data line of the microcapsule electrophoretic element and the DC component of the common potential of the counter electrode.
Therefore, in the case of W → W or B → W, there is a difference in white luminance (see FIGS. 20 and 21), and the first afterimage of the previous screen remains when the next screen is displayed. There's a problem.
The same problem occurs when B → B or W → B.

Furthermore, in order to make a high-definition electronic book display terminal device, display a dither pattern with two gradations, or colorize, it is necessary to make the pixel pitch 150 μm or less. As described above, when the pixel pitch is set to a sandwich pitch, it is recognized that a certain microcapsule type electrophoretic element is affected by the pixel voltage applied to the adjacent microcapsule type electrophoretic element.
Specifically, in order to display a dither pattern in a two-tone display, for example, the previous screen (Current Image) displays the pattern in black, and the subsequent screen (Next Image) has a checkered pattern. When displayed, it was observed that black floats, that is, the original display area of the pixel is reduced.
For example, there is a second afterimage problem that when a certain area of black characters is displayed on the previous screen and dither display is performed on the next screen, the previous characters remain.

  This problem is that in the conventional driving method, the pixel voltage is not written in the pixel in the character area (black) NTL shown on the left of FIG. 22 displayed on the previous screen and the black pixel in the dither pattern. When the pattern becomes a fine pattern of about 100 to 150 μm, the white display voltage of the adjacent pixel is picked up, and the white particles in the microcapsule located on the pixel electrode of the adjacent pixel come out on the surface. (Fig. 23)

As described above, when the screen is switched from black (B) to white (W) to black (B) to white (W), positive and negative voltages of +15 V, −15 V, +15 V, and −15 V are sequentially applied to the pixels. Since the pixel electrodes are alternately applied, no DC voltage is applied to the electrophoretic element.
However, a voltage of + 15V is applied to the pixel electrode for a number of frames in order to display the black state of black (B) → black (B) → black (B), or white (W) → white (W). → If a voltage of −15 V is continuously applied to the pixel electrode for a number of frames in order to display white (W) and a white state, a positive or negative DC current is constantly applied to the electrophoretic element to which these voltages are applied. Will continue to be applied.
Therefore, it has been found that even when the electrophoretic film is charged up and the display of the image is stopped at 0 V, there is a problem of image sticking in which the reverse display state of the image displayed only in the charge-up portion is displayed.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an electrophoretic display device capable of preventing afterimages and image sticking and a driving method thereof.

In order to solve the above-described problem, the first configuration of the present invention has a one-to-one correspondence at a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and intersections of the signal lines and the scanning lines. A pixel substrate having a plurality of pixel electrodes provided corresponding to the pixel electrode, a transparent counter electrode facing the pixel electrode, a counter substrate constituting a display surface, and the pixel substrate and the counter substrate. A first charged colored particle having a first color and a first polarity, and a second color different from the first color and a second polarity different from the first polarity. The present invention relates to an electrophoretic display device including an electrophoretic film having second charged colored particles, and selects a time-series voltage corresponding to input screen display data during a predetermined number of frames corresponding to screen update. The selected voltage in a time series between each pixel electrode and the counter electrode. Voltage selection means for applying the first charged colored particles to the display surface by applying a first voltage between the pixel electrodes and the counter electrode. The second voltage is applied between the first frame group for moving the second charged colored particles away from the display surface, and the pixel electrodes and the counter electrode. A second frame group for moving the second charged colored particles toward the display surface and moving the first charged colored particles away from the display surface, and the voltage selecting means comprises: During the predetermined number of frames corresponding to the screen update, the second (or first) charged colored particles are displayed from the display state by the first (or second) charged colored particles according to the rule expressed by the following formula: Special display It is set to.
Twb (+) + Tbw (+) = Twb (−) + Tbw (−)
Here, Twb (+) is the number of frames of the first frame group when transitioning from the display state with the first charged colored particles to the display state with the second charged colored particles, and Twb (−) is The number of frames of the second frame group, Tbw (+), is the number of frames of the first frame group when transitioning from the display state with the second charged colored particles to the display state with the first charged colored particles. , Tbw (−) represents the number of frames of the second frame group.

According to a second configuration of the present invention, a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and a plurality of one-to-one correspondence provided at the intersections of the signal lines and the scanning lines are provided. A pixel substrate having a pixel electrode; a transparent counter electrode facing the pixel electrode; a counter substrate constituting a display surface; and the pixel substrate interposed between the pixel substrate and the counter substrate; First charged colored particles having a first color and a first polarity; and second charged colored particles having a second color different from the first color and a second polarity different from the first polarity. The present invention relates to an electrophoretic display device comprising an electrophoretic film having
Select a time-series voltage corresponding to the input screen display data for a predetermined number of frames corresponding to the screen update, and apply the selected voltage between each pixel electrode and the counter electrode in time series Voltage selection means for applying a first voltage between each of the pixel electrodes and the counter electrode so that the predetermined number of frames apply the first charged colored particles to the display surface side. The second voltage is applied between the first frame group for moving the second charged colored particles away from the display surface, and the pixel electrodes and the counter electrode. 2 charged colored particles are moved to the display surface side, and the first charged colored particles are configured to include at least a second frame group for moving away from the display surface, and the voltage selecting means includes: The predetermined number of frames corresponding to the screen update Between, when to continue the display state according to the first or second charged color particles, in accordance with the rules represented by the following formula, prior to the first or second frame group, the second or the first It is characterized by applying an intermediate value of the voltage value .
V1xT1 = -V2xT2
Here, V1 is applied between the pixel electrode and the counter electrode of the electrophoretic element when the display state by the second charged colored particles is changed to the display state by the first charged colored particles. The intermediate value of the first voltage value , T1 is the number of frames to which the intermediate value V1 of the first voltage value is applied, and V2 is the second charged color from the display state by the first charged colored particles. An intermediate value of the second voltage value applied between the pixel electrode and the counter electrode of the electrophoretic element when transitioning to a display state by particles, T2 is an intermediate value of the second voltage value This represents the number of frames to which V2 is applied.

According to a third configuration of the present invention, a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and a plurality of lines provided in one-to-one correspondence at intersections of the signal lines and the scanning lines are provided. A pixel substrate having a pixel electrode; a transparent counter electrode facing the pixel electrode; a counter substrate constituting a display surface; and the pixel substrate interposed between the pixel substrate and the counter substrate; First charged colored particles having a first color and a first polarity; and second charged colored particles having a second color different from the first color and a second polarity different from the first polarity. In accordance with a driving method for driving an electrophoretic display device comprising an electrophoretic film, a time-series voltage corresponding to input screen display data is selected during a predetermined number of frames corresponding to screen update, The selected voltage is marked in time series between each pixel electrode and the counter electrode. In addition, a first voltage is applied to the predetermined number of frames between each pixel electrode and the counter electrode to move the first charged colored particles to the display surface side, and the second And applying the second voltage between the first group of frames for moving the charged colored particles away from the display surface and between the pixel electrodes and the counter electrode, A second frame group for moving to the display surface side and moving the first charged colored particles away from the display surface, and between the predetermined number of frames corresponding to the screen update According to the rule represented by the following formula, the display state by the first (or second) charged colored particles is changed to the display state by the second (or first) charged colored particles.
Twb (+) + Tbw (+) = Twb (−) + Tbw (−)
Here, Twb (+) is the number of frames of the first frame group when transitioning from the display state with the first charged colored particles to the display state with the second charged colored particles, and Twb (−) is The number of frames of the second frame group, Tbw (+), is the number of frames of the first frame group when transitioning from the display state with the second charged colored particles to the display state with the first charged colored particles. , Tbw (−) represents the number of frames of the second frame group.

According to a fourth configuration of the present invention, a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and a plurality of lines provided in one-to-one correspondence at the intersections of the signal lines and the scanning lines are provided. A pixel substrate having a pixel electrode; a transparent counter electrode facing the pixel electrode; a counter substrate constituting a display surface; and the pixel substrate interposed between the pixel substrate and the counter substrate; First charged colored particles having a first color and a first polarity; and second charged colored particles having a second color different from the first color and a second polarity different from the first polarity. In accordance with a driving method for driving an electrophoretic display device comprising an electrophoretic film, a time-series voltage corresponding to input screen display data is selected during a predetermined number of frames corresponding to screen update, The selected voltage is marked in time series between each pixel electrode and the counter electrode. In addition, a first voltage is applied to the predetermined number of frames between each pixel electrode and the counter electrode to move the first charged colored particles to the display surface side, and the second And applying the second voltage between the first group of frames for moving the charged colored particles away from the display surface and between the pixel electrodes and the counter electrode, A second frame group for moving to the display surface side and moving the first charged colored particles away from the display surface, and between the predetermined number of frames corresponding to the screen update When the display state by the first or second charged colored particles is continued, the second or first voltage value is set before the first or second frame group according to a rule represented by the following formula: as characterized by the application of the intermediate value That.
V1xT1 = -V2xT2
Here, V1 is applied between the pixel electrode and the counter electrode of the electrophoretic element when the display state by the second charged colored particles is changed to the display state by the first charged colored particles. The intermediate value of the first voltage value , T1 is the number of frames to which the intermediate value V1 of the first voltage value is applied, and V2 is the second charged color from the display state by the first charged colored particles. An intermediate value of the second voltage value applied between the pixel electrode and the counter electrode of the electrophoretic element when transitioning to a display state by particles, T2 is an intermediate value of the second voltage value This represents the number of frames to which V2 is applied.

According to the configuration of the present invention, no charge-up of the electrophoretic film occurs, so that it is possible to prevent afterimages and image sticking.

  The present invention relates to a pattern of one of two colors and a pattern of the other color that can be displayed on a pixel on a display surface of an electrophoretic display device in which a plurality of pixels (electrophoretic elements) are arranged in a matrix. When a screen consisting of the above is displayed, the frames forming the screen are composed of a frame group corresponding to one color in a predetermined order and a frame group corresponding to the other color, and are sequentially generated when the screen is displayed. When the frame group becomes a frame group of one of the two colors, a potential difference corresponding to the color of the frame group is set between the pixel electrode and the counter electrode of the electrophoretic element corresponding to the pixel of the pattern. It is comprised including making it apply.

  1 is a diagram showing a drive circuit of an active matrix microcapsule electrophoretic display device according to Embodiment 1 of the present invention, and FIG. 2 is a diagram showing a data driver of the active matrix microcapsule electrophoretic display device. FIG. 3 is a driving waveform diagram of the data driver of the active matrix microcapsule electrophoretic display device, and FIG. 4 is a transition from a white state to a white state in driving the active matrix microcapsule electrophoretic display device. FIG. 5 is a diagram for explaining the effect when a black state is inserted, FIG. 5 is a state transition diagram in driving the active matrix microcapsule electrophoretic display device, and FIG. 6 is an active matrix microcapsule electrophoresis. FIG. 7 is a diagram showing a state in which a second afterimage of the display device is generated, and FIG. It is a diagram showing a second state in which the afterimage is eliminated hex type microcapsule type electrophoretic display device.

  An active matrix type microcapsule type electrophoretic display device (hereinafter also referred to as an electrophoretic display device) 10 of this embodiment divides a frame forming a screen into a plurality of white frames and a plurality of black frames. A device that makes the number of frames written with white frames equal to the number of frames written with black frames, and makes the writing frame for particles with a large factor of slowing the movement of particles the last frame in the screen Therefore, as shown in FIG. 1, a microcapsule type electrophoretic element 100-mn (m = 1, 2,..., M, n = 1, 2,..., N) having a matrix arrangement of m rows and n columns. It is schematically configured to be driven by the scanning driver 12 and the data driver 14. The configuration of the microcapsule type electrophoretic element 100-mn itself is the same as that shown in FIG. The microcapsule-type electrophoretic element 100-mn constitutes an electrophoretic display panel as a whole.

The microcapsule type electrophoretic element 100-mn is connected to the scanning line Gm and the data line Dn via the TFT gate 104-mn.
The scanning driver 12 is a driver that outputs a negative gate voltage to the scanning line Gm, assuming that the TFT gate 104-mn is composed of a pMOS.
The data driver 14 is a time series that does not apply DC to the microcapsule type electrophoretic element 100-mn when the total frame of the rewrite is viewed in the rewriting of the pixel of the microcapsule type electrophoretic element 100-mn. It is a driver that sends a voltage to the data line Dn.

As shown in FIG. 2, the data driver 14 includes a selection signal generation circuit 26 and a voltage selection circuit 28. The selection signal generation circuit 26 outputs +15 volts (voltage when writing black (B)), 0 volt, and -15 volts (voltage when writing white (W)) from the voltage selection circuit 28. ) To output a time-series selection signal for outputting a time-series voltage, and the voltage selection circuit 28 sends a time series of voltages determined according to the selection signal to the data line Dn.
The selection signal is determined by the pixel data of each screen of the image, and is a signal switched according to the pixel data of each screen. That is, each screen includes a predetermined number of black frames and a predetermined number of white frames. Selection signals that cause W → W and B → B transitions within each screen and B → W and W → B transitions between sequential screens are generated so as to satisfy the following conditions (FIG. 3). ).

When the electrophoretic element 100-mn continues white (W) in a certain screen (when W → W → W... Continues), W is written in a predetermined number of white frames on the screen. Put black (B) transition in black frame before or after those white frames, ie write B in black frame before writing W in white frame on some screen or W in white frame B is written in the black frame after writing ((1) in FIG. 3).
In this case, the voltage applied to the pixel electrode 106-mn of the electrophoretic element 100-mn at the time of B writing is set to V + = + 15 V, while it is applied to the pixel electrode 106-mn of the electrophoretic element 100-mn at the time of W writing. The voltage to be written is V − = − 15V, the number of white frames for writing W is Tww−, and the number of black frames for writing B is Tww +.
Then, the following formula, that is,
Tww + = Tww- (1)
To satisfy.

Also, when the electrophoretic element 100-mn continues black in a certain screen (when B → B → B... Continues), B is written in a predetermined number of black frames on the screen. The white (W) transition is inserted in the white frame before or after the black frame, ie, the W write in the white frame before the B write in the black frame of a certain screen or the B write in the black frame Write W in the white frame after (4 in FIG. 3).
In this case, the voltage applied to the pixel electrode 106-mn of the electrophoretic element 100-mn at the time of W writing is V − = − 15V, while the voltage applied to the pixel electrode 106-mn of the electrophoretic element 100-mn at the time of B writing. The applied voltage is V + = + 15 V, the number of white frames for writing W is Tbb−, and the number of black frames for writing B is Tbb +.
Then, the following formula, that is,
Tbb + = Tbb- (2)
To satisfy.

In addition, when W → B is written on sequential screens, and B → W is written on subsequent screens ( the screen that immediately follows or the screen that follows) , the electrophoretic element 100-mn in W → B W writing. V − = − 15V, the voltage applied to the electrophoretic element 100-mn in the B writing is V + = + 15V, the number of white frames in which W writing is performed is Twb (−), and B Twb (+) is the number of black frames in which writing is performed, the voltage applied to the electrophoretic element 100-mn in B → W writing B is V + = + 15 V, and the electrophoretic element 100-mn in writing W V − = − 15V, the number of black frames for writing B is Tbw (+), and the number of white frames for writing W is Tbw (−).
Tbw (+) + Tbw (+) = Tbw (−) + Twb (−) (3)
And

Next, the operation of this embodiment will be described with reference to FIGS.
In this embodiment, in driving each electrophoretic element 100-mn of the electrophoretic display device, the electrophoretic element 100-mn is changed from a white display state (hereinafter also simply referred to as W) to a black display state (hereinafter simply referred to as “W”). The driving for the transition to B) and the transition for the electrophoretic element 100-mn from B to W are the same as in the prior art except for the following points.
That is, any screen displaying an image is configured by arranging a plurality of black frames and a plurality of white frames in a predetermined time-series order. The number of black frame groups and the number of white frame groups that are sequentially displayed on each screen are composed of different or the same number of frames.

A case where the display state of a certain screen is switched will be described.
In a black frame of a certain screen, a signal for turning on the TFT gate 104-mn is sent from the scanning driver 12 to the gate line Gm, and the data line Dn of the data driver 14 is sent to the pixel electrode 106-mn of the electrophoretic element 100-mn. In a state where B is written in the electrophoretic element 100-mn by applying a voltage of +15 volts and the electrophoretic element 100-mn is displayed in black, the electrophoretic element-mn is whitened in the white frame of the next screen. To make a transition to, a signal for turning on the TFT gate 104-mn is sent from the scanning driver 12 to the gate line Gm, and the pixel electrode of the electrophoretic element 100-mn from the data line Dn of the data driver 14 in the white frame of the screen A voltage of -15 volts is applied to 106-mn.

  The application of a voltage of −15 volts to the pixel electrode of the electrophoretic element 100-mn will be described with reference to FIG. 2. The selection signal generating circuit 26 that receives screen data generates white in the electrophoretic element 100-mn. In some cases, a negative voltage is output on the selection line corresponding to the pixel, for example, the selection line 30-n. As a result, the pMOS of the voltage selection circuit 28, for example, the pMOS 36-n is turned on and outputs a voltage of -15 volts to the data line Dn.

  In this way, when a voltage of −15 volts is applied to the pixel electrode 106-mn of the electrophoretic element 100-mn, the black carbon particles that are positively charged are attracted to the pixel electrode 106-mn, while negatively charged. The white titanium oxide particles are driven to the counter electrode 122. Thus, the electrophoretic element 100-mn transitions from the black state to the white state ((2) in FIG. 3).

Then, in order to transition the electrophoretic element 100-mn to B on the screen next to the screen in the transitioned white display state (W) (the above-mentioned next screen), the scan driver 12 changes to the gate line Gm. A signal for turning on the TFT gate 104-mn is sent, and a voltage of +15 volts is applied from the data line Dn of the data driver 14 to the pixel electrode 106-mn of the electrophoretic element 100-mn.
The application of a voltage of +15 volts to the pixel electrode of the electrophoretic element 100-mn will be described with reference to FIG. 2. The selection signal generating circuit 26 that receives screen data is supplied to the electrophoretic element 100-mn. In order to make a transition from B to B in the black frame of the next screen, a negative voltage is output on the selection line corresponding to the pixel, for example, the selection line 32-n. As a result, the pMOS of the voltage selection circuit 28, for example, the pMOS 38-n is turned on and outputs a voltage of +15 volts to the data line Dn.

  In this way, when a voltage of +15 volts is applied to the pixel electrode 106-mn of the electrophoretic element 100-mn, the white titanium oxide particles that are negatively charged are attracted to the pixel electrode 106-mn, while being positively charged. The black carbon particles are driven to the counter electrode 122. Thus, the electrophoretic element 100-mn transitions from the white state to the black state ((3) in FIG. 3).

In FIG. 3 showing the specific driving example described above, when W → B, the reason why the white voltage is once written is that when black frame T = 40 frames, white frame T = 20 frames when B → W. Therefore, 20 frames of white voltage are temporarily inserted.
As described above, when the electrophoretic element 100-mn repeats B and W for each screen, or when W and B are repeated for each screen, the electrophoretic element 100-mn calculates the number of black frames and W that cause B. The number of white frames to be generated is set so as to satisfy Equation (3) described above.
As a result, no DC voltage is applied to the electrophoretic element 100-mn, and the problem of image sticking does not occur.

The driving in the case where the electrophoretic element 100-mn is changed from W to W and the case where the electrophoretic element 100-mn is changed from B to B in this embodiment is as follows.
The driving when the electrophoretic element 100-mn is changed from W to W in an arbitrary screen is shown in FIG. 3 (1) when white is displayed in an arbitrary screen. Insert a black frame before the frame or between the white frame and the white frame.
The number of black frames Tww + inserted in this way is the same as the number of white frames Tww- that follows the black frame. In this case, in order to write B in the black frame and write W in the white frame, the voltage is applied to the pixel electrode 106-mn of the electrophoretic element 100-mn by the data driver 12 shown in FIG. Since the method of applying the voltage is the same as that described when the transition between the screens is caused, the description thereof is omitted.

Further, as shown in (4) of FIG. 3, the driving in the case where the electrophoretic element 100-mn is changed from B to B is performed before the black frame of the screen or when the B is displayed on an arbitrary screen. Insert a later white frame.
The frame number Tbb + of the black frame inserted in this way is assumed to be the same as the frame number Tbb- of the white frame that follows the black frame. In this case, in order to write B in the black frame and write W in the white frame, the voltage application to the pixel electrode 106-mn of the electrophoretic element 100-mn is also changed from W to W in an arbitrary screen. The same.

According to this driving method, as shown in FIG. 4, when the electrophoretic element 100-mn is changed from W to W, if B is inserted between W and W, the electrophoretic element is charged up. In addition, no image sticking occurs, and a negative voltage (white voltage) is applied for display, so that the white luminance is reduced as compared with the case where the white state is maintained in the memory characteristics (described above). It was experimentally confirmed that the first afterimage) can be prevented.
In addition, when transitioning from B to B, if W is inserted between them, an increase in black luminance (the first afterimage described above) can be prevented as compared with a case where a black state is to be maintained with memory characteristics. Has been confirmed experimentally.

FIG. 5 shows the drive state transition in this embodiment.
In FIG. 5, 15V of 15V / −15V in W → W is a voltage for inserting B between W and W, and −15V is for transition from B to W from W to B. Is the voltage. In addition, −15V of −15V / 15V in B → B is a voltage for inserting W between B and B, and 15V is a voltage for transitioning from W to B from B to W. It is.
At this time, when a transition of W → B (the number of frames T1) → W (the number of frames T2) is caused in a certain screen, T1 = T2, and B → W (the number of frames T3 in the certain screen). ) → B (the number of frames T4), as described above, T3 = T4 as described above.

The problem of the second afterimage described above is that when the pixel electrode has a fine pattern of about 100 to 150 μm, the particles in the microcapsules of the electrophoretic element are caused by the leakage electric field generated by the pixel voltage of the adjacent electrophoretic element. Caused by being affected.
This problem arises when there is a leakage electric field from an electrophoretic element adjacent to the electrophoretic element even when no voltage is applied to the pixel electrode of the electrophoretic element or when a voltage is applied.

The second afterimage problem also depends on the difference in charge amount of different particles in the microcapsule. It is difficult to make the charge amount of the white particles in the microcapsule equal to the charge amount of the black particles. In the EDP element evaluated by the present inventor, since the charge amount of TiO as white particles is larger than the charge amount of carbon particles as black particles, the white particles move faster.
Therefore, when the microcapsule is positioned between the pixel electrodes, the surface of the microcapsule becomes white, and the white particles enter the adjacent pixel (FIG. 6). For this reason, black will float.

In order to solve this problem, the white frame is divided into the black frame, and the frame having the smaller charge amount, mobility, etc. of the particle, for example, in the evaluated EDP element example, the black frame is the last, and the number of black frames is We adopted the means of making it the required number.
When this means is used, the white particles once penetrate into the neighboring pixels, but black is written next, so that the black particles and the white particles can be divided into regions in the microcapsule at the pixel boundary. (FIG. 7), the second afterimage problem can be solved.
The reason why the black particles did not penetrate into the adjacent pixel electrode is considered to be that the charge amount, mobility, etc. of the black particles are smaller than those of the white particles and the number of writing frames is optimized.

As described above, it has been proved that it is useful for solving the problems of the first afterimage, the second afterimage, and the image sticking described in the [Background Art] section.
In summary, the drive method described above is divided into a white frame and a black frame for writing to the electrophoretic element, and a writing frame for particles having a small charge amount is the last.
Then, when trying to cause the transition of W → W, B is written in the black frame before or after W written in the white frame in the screen, and at that time, the above-described expression (1) is satisfied. Like that.
When an attempt is made to cause a transition from B to B, W is written in the white frame before or after B written in the white frame in the screen, and at this time, the above equation (2) is satisfied. Like that.
In addition, when W → B is written on sequential screens and then B → W is written, the above-described equation (3) is satisfied.

Thus, according to this embodiment, when the screen is divided into a predetermined number of white frames and black frames and a W → W transition occurs in the screen, the writing of B before or after the writing of W is inserted. Since the number of W and B write frames satisfies the expression (1), it helps to eliminate the first afterimage and burn-in that occur at the transition from W to W.
In addition, when a B → B transition occurs in the screen, the writing of W is performed before or after the writing of B, and the number of writing frames of these B and W satisfies the formula (2). It helps to eliminate the first afterimage and image sticking that occur at the transition of B → B.
Also, if the black frame is written at the end of the screen, it helps to eliminate the second afterimage.

  FIG. 8 is a diagram illustrating the relationship between the voltage of the counter electrode and the voltage of the pixel electrode in driving the electrophoretic display device according to the first embodiment, and FIG. 9 illustrates driving of the electrophoretic display device according to the second embodiment of the present invention. It is a voltage wave form diagram applied to a counter electrode in FIG.

The configuration of this embodiment is greatly different from that of the first embodiment in that the electrophoretic element of the electrophoretic display device is driven by a binary driver.
Specifically, the above-described driving is dot inversion driving without changing the COM voltage, that is, Vcom = 0 V, and HDriver (data driver) uses a ternary driver of +15 V / 0 V / −15 V. (FIG. 8). In other words, this ternary driver always maintains the counter electrode voltage (COM voltage) at 0 V, and the pixel electrode voltage is set to −15 V for the white frame, and +15 V for the black frame. It is. It is also possible to drive an equivalent electrophoretic element with a binary driver as described above, and this is a feature of this embodiment.

The basic configuration of this feature is that the voltage applied to the pixel electrode is set to + 15V or 0V in the white frame and the black frame, while the COM voltage is set to 15V during the transition in the white frame described above, At the time of transition in the black frame, the COM voltage is swung between + 15V and 0V so that the COM voltage is 0V.
With this configuration, in the case of a white frame, when +15 volts is applied to the counter electrode (the section of +15 volts of the solid line in FIG. 9) and +15 V is applied to the pixel electrode, the pixel electrode (pix) and the counter electrode When the potential difference is 0 volt, +15 volts is applied to the counter electrode (section of +15 volts of the solid line in FIG. 9) and 0 V is applied to the pixel electrode, the potential difference between the pixel electrode (pix) and the counter electrode is −15 volts. It becomes.

In the case of a black frame, when 0 volt is applied to the counter electrode (0 volt section of the solid line in FIG. 9) and +15 V is applied to the pixel electrode, the potential difference between the pixel electrode (pix) and the counter electrode is When the voltage is +15 volts, 0 volt is applied to the counter electrode (interval of 0 volt of the solid line in FIG. 9) and 0 V is applied to the pixel electrode, the potential difference between the pixel electrode (pix) and the counter electrode is 0 volt.
Therefore, even a binary driver can be driven in the same manner as a ternary driver according to the driving method described above.

  As described above, according to the configuration of this embodiment, the binary driver can enjoy the same effect as that of the first embodiment, which helps to reduce the cost.

FIG. 10 is a transition diagram of driving performed in the electrophoretic display device according to the third embodiment of the present invention, FIG. 11 is a driving waveform diagram of the electrophoretic display device, and FIG. 12 is the driving waveform of the first or second embodiment. FIG. 13 is a time chart for explaining the advantages of the third embodiment.
The configuration of this embodiment is greatly different from that of the first or second embodiment. The first or second embodiment is configured to prevent a flickering display state from entering when the screen is changed. Is a point.

That is, the electrophoretic display device according to this embodiment, when continuously updating the display state of W, when causing a transition of W → B → W, sets the voltage in the black frame at the transition of W → B to + V ( Vwb), for example, not to +15 volts, but to an intermediate potential (Vwb2) that brings the electrophoretic element to a light gray (LG) display state, for example, +7.5 volts, as shown in FIGS. When the white frame is returned to -15 volts and the B display state is continuously updated, when the B → W → B transition occurs, the voltage at the white frame at the B → W transition is -V (Vwb), for example, -15 volts, rather than an intermediate potential (Vbw2) that places the electrophoretic element in a dark gray (DG) display state, for example, +15 volts in the black frame after having been +12 volts Return to.

In addition to this, when the number of frames to which the intermediate potential of Vwb2 is applied is T1, and the number of frames to which the intermediate potential of Vbw2 is applied is T2,
Vwb2 × T1 = Vbw2 × T2 (4)
And
Thereby, generation | occurrence | production (charge up) of DC potential can be suppressed in an electrophoretic film.
By satisfying the above equation (4), it is possible to suppress the charge-up, but in the sense of the movement of black particles in the microcapsule, even if the above equation (4) is established, the amount of movement of the black particles is not the same. This is because the amount of movement of black particles is small when the voltage is low.

In this way, in the first or second embodiment, as shown in FIG. 12, when W → B → W is driven, black followed by white and flickering white, ie, flickering. Although there is an inconvenience that glare (uncomfortable feeling) occurs (flushing occurs), since the display state of light gray and white is followed by white by performing the driving of the above-described third embodiment, it occurs in the display. Discomfort can be greatly relieved.
According to the driving method in the first embodiment or the second embodiment, in the drive of B → W → B, there is an inconvenience that flickering of white followed by black and black, that is, flickering (uncomfortable feeling) occurs. However, according to the driving of the above-described third embodiment, since the display state of black is followed by dark gray and black, the uncomfortable feeling generated in the display can be relieved greatly.

  As described above, according to this embodiment, the effect of the first embodiment or the second embodiment can be enjoyed, and the flushing can be alleviated.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and the design does not depart from the gist of the present invention. These changes are included in the present invention.
For example, in the embodiment, formula (1) is established when W → W → W... Continues in the screen, and formula (2) is established when B → B → B. However, this is not always necessary, and even a slight difference is allowed.
Similarly, although it has been described that the expression (3) is established in the case of driving in which W → B → B → W between the screens, it is not always necessary, and there may be slight differences.
Similarly, although it has been described that the expression (4) is established in the case of the third embodiment, it is not always necessary, and there may be a slight difference.
Even if the microcapsule type electrophoretic element configured by storing white charged particles and black charged particles in a capsule is used as charged particles of the other two colors while inheriting the above, the present invention Can be implemented.
Also, the PET counter substrate has been described with respect to a transparent plastic substrate with a single counter electrode attached thereto. For example, the PET counter substrate extends in the scanning line direction and is configured with each counter electrode in that direction. May be.

  The driving method of the electrophoretic display device disclosed herein and the device thereof can be used as various display devices such as an information processing device, a mobile terminal device, a video camera display device, a television, and the like.

It is a figure which shows the drive circuit of the electrophoretic display device which is Example 1 of this invention. It is a figure which shows the data driver of the same electrophoretic display device. It is a drive waveform diagram of the data driver of the same electrophoretic display device. It is a figure explaining the effect at the time of putting a black state in the transition from W to W in the drive of the same electrophoretic display device. It is a state transition diagram in the drive of the same electrophoretic display device. It is a figure which shows the state in which the 2nd afterimage of the same electrophoretic display device generate | occur | produces. It is a figure which shows the state from which the 2nd afterimage of the same electrophoretic display device is lose | eliminated. 6 is a diagram illustrating a relationship between a voltage of a counter electrode and a voltage of a pixel electrode in driving of an electrophoretic display device that is Embodiment 1. FIG. It is a voltage wave form diagram applied to a counter electrode in the drive of the electrophoretic display device which is Example 2 of this invention. It is the transition diagram of the drive performed with the electrophoretic display device which is Example 3 of this invention. It is a drive waveform diagram of the same electrophoretic display device. 6 is a time chart for explaining a defect of the first embodiment or the second embodiment. 10 is a time chart for explaining the advantages of the third embodiment. It is sectional drawing of the structure of the conventional microcapsule-type electrophoretic element panel. It is a schematic diagram of the electrophoretic element of the matrix-like arrangement of the electrophoretic display device. It is a figure which shows the drive circuit of the same electrophoretic display device. It is a figure which shows the partial structure of the data driver of the same electrophoretic display device. It is a drive waveform diagram of the data driver of the same electrophoretic display device. It is a transition diagram which drives the same electrophoretic display device. FIG. 5 is a diagram for explaining a first afterimage problem that occurs in the electrophoretic display device. 3 is a time chart for explaining a problem of a first afterimage generated in the electrophoretic display device. It is a figure explaining the problem of the 2nd afterimage which arises in the same electrophoretic display device. It is a panel sectional view for explaining the problem of the 2nd afterimage which arises in the same electrophoretic display device.

Explanation of symbols

10 Active Matrix Microcapsule Electrophoretic Display Device 12 Scan Driver 14 Data Driver (First Means, Second Means)
26 Selection signal generation circuit (part of the first means, part of the second means)
28 Voltage selection circuit (the remainder of the first means, the remainder of the second means)

Claims (6)

A pixel substrate having a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and a plurality of pixel electrodes provided in one-to-one correspondence at intersections of the signal lines and the scanning lines; A transparent counter electrode facing the pixel electrode, interposed between the counter substrate constituting the display surface, the pixel substrate and the counter substrate, and having a first color and a first polarity Electrophoresis comprising first charged colored particles and an electrophoretic film having a second color different from the first color and a second charged colored particle having a second polarity different from the first polarity. A display device,
Select a time-series voltage corresponding to the input screen display data for a predetermined number of frames corresponding to the screen update, and apply the selected voltage between each pixel electrode and the counter electrode in time series Voltage selection means for
The predetermined number of frames is
A first voltage is applied between each of the pixel electrodes and the counter electrode to move the first charged colored particles toward the display surface, and to move the second charged colored particles away from the display surface. A first frame group for,
The second voltage is applied between each pixel electrode and the counter electrode to move the second charged colored particles to the display surface side, and the first charged colored particles are moved from the display surface. And at least a second frame group for moving away, and
The voltage selection means performs the second (or first) from the display state by the first (or second) charged colored particles in accordance with the rule expressed by the following equation during the predetermined number of frames corresponding to the screen update. The electrophoretic display device is caused to transition to a display state by charged colored particles.
Twb (+) + Tbw (+) = Twb (−) + Tbw (−)
Here, Twb (+) is the number of frames of the first frame group when transitioning from the display state with the first charged colored particles to the display state with the second charged colored particles, and Twb (−) is The number of frames of the second frame group, Tbw (+), is the number of frames of the first frame group when transitioning from the display state with the second charged colored particles to the display state with the first charged colored particles. , Tbw (−) represents the number of frames of the second frame group. A pixel substrate having a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and a plurality of pixel electrodes provided in one-to-one correspondence at intersections of the signal lines and the scanning lines; A transparent counter electrode facing the pixel electrode, interposed between the counter substrate constituting the display surface, the pixel substrate and the counter substrate, and having a first color and a first polarity Electrophoresis comprising first charged colored particles and an electrophoretic film having a second color different from the first color and a second charged colored particle having a second polarity different from the first polarity. A display device,
Select a time-series voltage corresponding to the input screen display data for a predetermined number of frames corresponding to the screen update, and apply the selected voltage between each pixel electrode and the counter electrode in time series Voltage selection means for
The predetermined number of frames is
A first voltage is applied between each of the pixel electrodes and the counter electrode to move the first charged colored particles toward the display surface, and to move the second charged colored particles away from the display surface. A first frame group for,
The second voltage is applied between each pixel electrode and the counter electrode to move the second charged colored particles to the display surface side, and the first charged colored particles are moved from the display surface. And at least a second frame group for moving away, and
When the voltage selection means continues the display state by the first or second charged colored particles during the predetermined number of frames corresponding to the screen update, the first or second voltage selection means follows the rule expressed by the following formula: An electrophoretic display device, wherein an intermediate value of the second or first voltage value is applied before a second frame group.
V1xT1 = -V2xT2
Here, V1 is applied between the pixel electrode and the counter electrode of the electrophoretic element when the display state by the second charged colored particles is changed to the display state by the first charged colored particles. The intermediate value of the first voltage value , T1 is the number of frames to which the intermediate value V1 of the first voltage value is applied, and V2 is the second charged color from the display state by the first charged colored particles. An intermediate value of the second voltage value applied between the pixel electrode and the counter electrode of the electrophoretic element when transitioning to a display state by particles, T2 is an intermediate value of the second voltage value This represents the number of frames to which V2 is applied.   The predetermined number of frames includes a period in which a 0 V voltage that does not move the first and second charged particles is applied between each pixel electrode and the counter electrode. 3. The electrophoretic display device according to 1 or 2. A pixel substrate having a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and a plurality of pixel electrodes provided in one-to-one correspondence at intersections of the signal lines and the scanning lines; A transparent counter electrode facing the pixel electrode, interposed between the counter substrate constituting the display surface, the pixel substrate and the counter substrate, and having a first color and a first polarity Electrophoresis comprising first charged colored particles and an electrophoretic film having a second color different from the first color and a second charged colored particle having a second polarity different from the first polarity. A driving method for driving a display device,
Select a time-series voltage corresponding to the input screen display data for a predetermined number of frames corresponding to the screen update, and apply the selected voltage between each pixel electrode and the counter electrode in time series As well as
The predetermined number of frames,
A first voltage is applied between each of the pixel electrodes and the counter electrode to move the first charged colored particles toward the display surface, and to move the second charged colored particles away from the display surface. A first frame group for,
The second voltage is applied between each pixel electrode and the counter electrode to move the second charged colored particles to the display surface side, and the first charged colored particles are moved from the display surface. Comprising at least a second frame group for moving away, and
During the predetermined number of frames corresponding to the screen update, the display state by the first (or second) charged colored particles is changed from the display state by the first (or second) charged colored particles according to the rule expressed by the following formula. A driving method of an electrophoretic display device, characterized by causing a transition to a display state.
Twb (+) + Tbw (+) = Twb (−) + Tbw (−)
Here, Twb (+) is the number of frames of the first frame group when transitioning from the display state with the first charged colored particles to the display state with the second charged colored particles, and Twb (−) is The number of frames of the second frame group, Tbw (+), is the number of frames of the first frame group when transitioning from the display state with the second charged colored particles to the display state with the first charged colored particles. , Tbw (−) represents the number of frames of the second frame group. A pixel substrate having a plurality of signal lines, a plurality of scanning lines intersecting with these signal lines, and a plurality of pixel electrodes provided in one-to-one correspondence at intersections of the signal lines and the scanning lines; A transparent counter electrode facing the pixel electrode, interposed between the counter substrate constituting the display surface, the pixel substrate and the counter substrate, and having a first color and a first polarity Electrophoresis comprising first charged colored particles and an electrophoretic film having a second color different from the first color and a second charged colored particle having a second polarity different from the first polarity. A driving method for driving a display device,
Select a time-series voltage corresponding to the input screen display data for a predetermined number of frames corresponding to the screen update, and apply the selected voltage between each pixel electrode and the counter electrode in time series As well as
The predetermined number of frames,
A first voltage is applied between each of the pixel electrodes and the counter electrode to move the first charged colored particles toward the display surface, and to move the second charged colored particles away from the display surface. A first frame group for,
The second voltage is applied between each pixel electrode and the counter electrode to move the second charged colored particles to the display surface side, and the first charged colored particles are moved from the display surface. Comprising at least a second frame group for moving away, and
When the display state by the first or second charged colored particles is continued during the predetermined number of frames corresponding to the screen update, according to the rule represented by the following formula, the first or second frame group A driving method of an electrophoretic display device, wherein an intermediate value of the second or first voltage value is applied before .
V1xT1 = -V2xT2
Here, V1 is applied between the pixel electrode and the counter electrode of the electrophoretic element when the display state by the second charged colored particles is changed to the display state by the first charged colored particles. The intermediate value of the first voltage value , T1 is the number of frames to which the intermediate value V1 of the first voltage value is applied, and V2 is the second charged color from the display state by the first charged colored particles. An intermediate value of the second voltage value applied between the pixel electrode and the counter electrode of the electrophoretic element when transitioning to a display state by particles, T2 is an intermediate value of the second voltage value This represents the number of frames to which V2 is applied.   The predetermined number of frames includes a period in which a 0 V voltage that does not move the first and second charged particles is applied between each pixel electrode and the counter electrode. 6. A method for driving an electrophoretic display device according to 4 or 5.

Images