JP2013195896A - Controller of display device, control method of display device, display device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the charge amount that pixels have from being biased to suppress deterioration in pixels.SOLUTION: When detected temperature changes after writing operation of gradation change of pixels finishes at a seventh frame, voltage is applied on pixels to a thirteenth frame so that the difference between the number of times of voltage application at a moment when a pixel is made black and the number of times of voltage application at a moment when a pixel is made white becomes zero. After the difference becomes zero, voltage is applied to pixels at the number of times of application according to the detected temperature to make all pixels black, and voltage is applied to pixels at the number of times of application according to the detected temperature to make all pixels white. After all pixels are made white, voltage is applied to the pixels at the number of times of application according to the detected temperature, so that the image stored in a buffer is displayed.

Description

  The present invention relates to a display device control device, a display device control method, a display device, and an electronic apparatus.

  As an invention relating to the display quality of the electro-optical device, there is an electro-optical device disclosed in Patent Document 1, for example. This electro-optical device uses electrophoretic particles, and by applying an electric field to the electrophoretic particles in the dispersion medium, the colored electrophoretic particles are moved to display an image. In an electro-optical device using a dispersion medium and electrophoretic particles, the viscosity of the dispersion medium changes depending on the temperature, so that a desired gradation may not be obtained even when the same electric field is applied. For this reason, this electro-optical device controls the amount of movement of the electrophoretic particles by changing the electric field applied according to the temperature, even when displaying the same gradation, and the desired amount of temperature can be changed. Gradation is displayed.

JP 2004-85606 A

  By the way, in a display device using electrophoretic particles, when the display is changed by the active matrix method, the electrophoretic particles are moved by applying a voltage to the electrode sandwiching the dispersion medium and the electrophoretic particles multiple times. is there. Specifically, for example, in the case of a display device that performs two-tone display of white and black, when a pixel is black, a positive voltage is applied multiple times, and when a pixel is white, Control of applying a negative voltage a plurality of times is performed. In this configuration, it is necessary to change the number of voltage applications so that a desired gradation is displayed when the temperature changes. For example, even when the same gradation is displayed, the number of times of application is increased if the temperature is low, and the number of times of application is decreased if the temperature is high.

  In this configuration, the number of applied voltages is the same between black and white pixels, but the polarity of the applied voltage is different. For this reason, in a state where the temperature does not change and the number of times of application is not changed, for example, when the pixel is set to white after the pixel is set to black, the charge amount held by the pixel is maintained at a constant value. However, after setting the pixel to a black state, the number of times of application is set by lowering the temperature, and then changing the pixel to white, the polarity of the applied voltage and the number of times of application when the pixel is black, Since the polarity of the applied voltage when the pixel is white and the number of times of application are not balanced, and the amount of charge held by the pixel does not become a constant value, the pixel may deteriorate quickly.

  The present invention has been made in view of the above-described circumstances, and one of its purposes is to suppress the deterioration of the pixel by suppressing the bias of the charge amount held by the pixel.

In order to achieve the above object, a control device for a display device according to the present invention includes a plurality of first electrodes provided for each pixel, a second electrode disposed to face the plurality of first electrodes, A control device for a display device, comprising: a plurality of first electrodes; and an electro-optic material disposed between the second electrodes, wherein the gradation of the pixel is changed from a second gradation to a first gradation. In the case of changing in the direction, the first writing operation of applying the first voltage to the first electrode of the pixel a plurality of times is performed, and the gradation of the pixel is changed from the first gradation to the second gradation. When changing in the direction, a writing unit for performing a second writing operation for applying a second voltage having a polarity different from that of the first voltage to the first electrode of the pixel a plurality of times; Number of times of application of the first voltage and application of the second voltage in the second write operation In the case of changing the number, at least one of the charge amount held by the electro-optic material converges to a predetermined charge amount when the potential of the first electrode and the potential of the second electrode are the same potential. When the adjustment unit that applies a voltage to the first electrode of the pixel and the number of times of applying the first voltage and the number of times of applying the second voltage are changed, the amount of charge held by the electro-optic material of each pixel is determined in advance. And a changing unit configured to change the number of times of application of the first voltage in the first write operation and the number of times of application of the second voltage in the second write operation while converging to a predetermined charge amount.
According to this configuration, when changing the number of times of application applied to the first electrode of the pixel in the writing operation, the amount of charge held by the electro-optic material of each pixel is converged to a predetermined amount of charge. Since the number of times of application is changed, there is no bias in the amount of charge held by the pixel, and deterioration of the pixel can be suppressed.

In the control device, after the changing unit changes the number of times of application of the first voltage and the number of times of application of the second voltage, the gradation of the plurality of pixels is changed to the first gradation or the second gradation. It is good also as composition to do.
According to this configuration, since the image is displayed after the gradation of each pixel is aligned after changing the number of times of application, it is possible to suppress a difference in gradation between pixels when displaying the same gradation. Can do.

In the control device, after the amount of charge held by the electro-optic material of each pixel is converged to a predetermined amount of charge by the adjustment unit, the gradation of the plurality of pixels is changed to the first gradation or the It is good also as a structure which makes it a 2nd gradation.
According to this configuration, since the number of times of application is changed after the gradation of each pixel is aligned and the image is displayed after that, it is possible to suppress a difference in gradation between pixels when displaying the same gradation. be able to.

In the control device, in the first write operation, the second voltage is applied in addition to the first voltage, and the number of times of application of the first voltage is greater than the number of times of application of the second voltage, In the second write operation, the first voltage is applied in addition to the second voltage, and the number of times of application of the second voltage is greater than the number of times of application of the first voltage. The difference between the number of times of application of the first voltage and the number of times of application of the second voltage is the same as the difference between the number of times of application of the second voltage and the number of times of application of the first voltage in the second write operation. It is good also as a structure.
According to this configuration, since the first voltage and the second voltage having different polarities are applied in the writing operation, the electro-optic material can be controlled and the gradation can be displayed with high accuracy.

The controller may be configured such that the number of times of application of the first voltage in the first write operation is the same as the number of times of application of the second voltage in the second write operation.
According to this configuration, the voltage of the same polarity is applied in each writing operation, and the voltage of the other polarity is not applied, so that the writing operation is simplified.

The controller may be configured such that the number of times of application of the first voltage in the first write operation is different from the number of times of application of the second voltage in the second write operation.
According to this configuration, even if the electro-optic material constituting the pixel is an electro-optic material in which the number of times of voltage application differs between the first gradation and the second gradation, Since the number of times of application is changed while the amount of charge held by the electro-optic material converges to a predetermined amount of charge, there is no bias in the amount of charge held by the pixel, and deterioration of the pixel can be suppressed. it can.

The controller may be configured to change the number of times of application of the first voltage and the number of times of application of the second voltage when the temperature detected by a sensor that detects temperature changes.
According to this configuration, even if the electro-optic material constituting the pixel is an electro-optic material in which the number of times of voltage application in the writing operation needs to be changed depending on the temperature, the amount of charge held by the electro-optic material of each pixel Is converged to a predetermined charge amount, the number of times of application is changed. Therefore, there is no bias in the charge amount held by the pixel, and deterioration of the pixel can be suppressed.

In the control device, any one of a mode in which the number of gradations displayed by the pixel is two gradations of the first gradation and the second gradation and a mode in which the number of gradations exceeds the two gradations is selected. The switching unit may be configured to change the number of times of applying the first voltage and the number of times of applying the second voltage when switching the mode.
According to this configuration, even if the electro-optic material needs to change the number of times of voltage application in the writing operation depending on the temperature according to the number of gradations to be displayed, the amount of charge held by the electro-optic material of each pixel is small. Since the number of times of application is changed while converging on a predetermined charge amount, the charge amount held by the pixel is not biased, and deterioration of the pixel can be suppressed.

In order to achieve the above object, a display device according to the present invention includes a plurality of first electrodes provided for each pixel, a second electrode disposed to face the plurality of first electrodes, and the plurality of the plurality of first electrodes. An electro-optic material disposed between the first electrode and the second electrode, wherein the gray level of the pixel is changed from the second gray level to the first gray level. In this case, a first writing operation in which a first voltage is applied to the first electrode of the pixel a plurality of times is performed, and the gray level of the pixel is changed from the first gray level to the second gray level. Includes a writing unit for performing a second writing operation in which a second voltage having a polarity different from that of the first voltage is applied to the first electrode of the pixel a plurality of times, and application of the first voltage in the first writing operation. The number of times and the number of times the second voltage is applied in the second write operation. In the state where the potential of the first electrode and the potential of the second electrode are the same potential, the charge amount held by the electro-optic material converges to a predetermined charge amount. An adjustment unit that applies a voltage to one electrode, and a charge amount that the electro-optic material of each pixel holds is predetermined when changing the number of times of applying the first voltage and the number of times of applying the second voltage. And a changing unit that changes the number of application times of the first voltage in the first write operation and the number of application times of the second voltage in the second write operation.
According to this configuration, when changing the number of times of application applied to the first electrode of the pixel in the writing operation, the amount of charge held by the electro-optic material of each pixel is converged to a predetermined amount of charge. Since the number of times of application is changed, there is no bias in the amount of charge held by the pixel, and deterioration of the pixel can be suppressed.

  Note that the present invention can be conceptualized not only as a display device control device and a display device, but also as a display device control method and an electronic apparatus including the display device.

The figure which showed the hardware constitutions of the display apparatus 1000 concerning 1st Embodiment. The figure which showed the cross section of the display area. FIG. 6 is a diagram showing an equivalent circuit of the pixel 110. The figure for demonstrating the structure of a storage area. The block diagram which showed the structure of the function implement | achieved by the controller 5. FIG. The flowchart which showed the flow of the process which the controller 5 performs. The flowchart which showed the flow of the process which the controller 5 performs. The flowchart which showed the flow of the process which the controller 5 performs. The flowchart which showed the flow of the process which the controller 5 performs. The flowchart which showed the flow of the process which the controller 5 performs. The figure for demonstrating operation | movement of 1st Embodiment. The figure which showed the structure of RAM4 which concerns on 2nd Embodiment. The figure which showed the structure of the balance storage area D. FIG. The flowchart which showed the flow of the process which the controller 5 of 2nd Embodiment performs. The flowchart which showed the flow of the process which the controller 5 of 2nd Embodiment performs. The flowchart which showed the flow of the process which the controller 5 of 2nd Embodiment performs. The figure for demonstrating operation | movement of 2nd Embodiment. The external view of the electronic book reader 2000. FIG. The flowchart which showed the flow of the process which the controller 5 of 2nd Embodiment performs. The flowchart which showed the flow of the process which the controller 5 which concerns on a modification performs.

[Embodiment]
(Configuration of the embodiment)
FIG. 1 is a block diagram showing a hardware configuration of a display apparatus 1000 according to an embodiment of the present invention. The display device 1000 is a device that displays an image, and includes an electrophoretic electro-optical device 1, a control unit 2, a VRAM (Video Random Access Memory) 3, and a RAM 4 that is an example of a storage unit. The electro-optical device 1 includes a display unit 10 and a controller 5.

The control unit 2 is a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM, and the like, and controls each unit of the display device 1000. The control unit 2 accesses the VRAM 3 and writes image data indicating an image to be displayed in the display area 100 to the VRAM 3.
The controller 5 supplies various signals for displaying an image on the display area 100 of the display unit 10 to the scanning line driving circuit 130 and the data line driving circuit 140 of the display unit 10. The controller 5 corresponds to the control device of the electro-optical device 1. Note that the combined portion of the control unit 2 and the controller 5 can be defined as the control device of the electro-optical device 1. Alternatively, the entire control unit 2, controller 5, VRAM 3, and RAM 4 can be defined as a control device for the electro-optical device 1.

The VRAM 3 is a memory that stores image data written by the control unit 2. The VRAM 3 has a storage area (buffer) for each pixel 110 arranged in m rows and n columns, which will be described later. The image data includes pixel data representing the gradation of each pixel 110, and the pixel data representing the gradation of one pixel 110 is stored in one storage area corresponding to the pixel 110 in the VRAM 3. Pixel data written in the VRAM 3 is read by the controller 5.
The temperature sensor 6 is a sensor that detects temperature. The temperature sensor 6 outputs a signal representing the detected temperature. The temperature sensor 6 is disposed in the vicinity of the display area 100.
The RAM 4 stores various data used for displaying an image on the display area 100. The RAM 4 is provided with a counter storage area B and a scheduled image storage area E.
The RAM 4 is provided with a voltage application number N_PRE, which is an area for storing the voltage application number. Details of the storage area provided in the RAM 4 will be described later.

  In the display region 100, a plurality of scanning lines 112 are provided along the row (X) direction in the figure, and the plurality of data lines 114 are electrically connected to each scanning line 112 along the column (Y) direction. It is provided to keep insulation. Pixels 110 are provided corresponding to the intersections of the scanning lines 112 and the data lines 114, respectively. For convenience, when the number of rows of the scanning lines 112 is “m” and the number of columns of the data lines 114 is “n”, the pixels 110 are arranged in a matrix in m rows and n columns. Will be configured.

FIG. 2 is a view showing a cross section of the display region 100. As shown in FIG. 2, the display area 100 is roughly configured by a first substrate 101, an electrophoretic layer 102, and a second substrate 103. The first substrate 101 is a substrate in which a circuit layer is formed on an insulating and flexible substrate 101a. The substrate 101a is made of polycarbonate in this embodiment. Note that the substrate 101a is not limited to polycarbonate, and a resin material having lightness, flexibility, elasticity, and insulation can be used. In addition, the substrate 101a may be formed of non-flexible glass. An adhesive layer 101b is provided on the surface of the substrate 101a, and a circuit layer 101c is laminated on the surface of the adhesive layer 101b.
The circuit layer 101c has a plurality of scanning lines 112 arranged in the row direction and a plurality of data lines 114 arranged in the column direction. The circuit layer 101c has pixel electrodes 101d corresponding to the intersections of the scanning lines 112 and the data lines 114, respectively.

  The electrophoretic layer 102, which is an example of an electro-optic material, includes a binder 102b and a plurality of microcapsules 102a fixed by the binder 102b, and is formed on the pixel electrode 101d. Note that an adhesive layer formed using an adhesive may be provided between the microcapsule 102a and the pixel electrode 101d.

  The binder 102b is not particularly limited as long as it has good affinity with the microcapsule 102a, excellent adhesion to the electrode, and has insulating properties. A dispersion medium and electrophoretic particles are stored in the microcapsule 102a. As a material constituting the microcapsule 102a, it is preferable to use a flexible material such as a gum arabic / gelatin compound or a urethane compound.

  Dispersion media include water, alcohol solvents (methanol, ethanol, isopropanol, butanol, octanol, methyl cellosolve, etc.), esters (ethyl acetate, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.) , Aliphatic hydrocarbons (pentane, hexane, octane, etc.), alicyclic hydrocarbons (cyclohexane, methylcyclohexane, etc.), aromatic hydrocarbons (benzene, toluene, benzenes with long chain alkyl groups (xylene) Hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene)), halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) 1,2-dichloroethane, etc.), it can be any of such carboxylates, and the dispersion medium may be other oils. These substances can be used alone or in combination as a dispersion medium, and a surfactant or the like may be further blended to form a dispersion medium.

  Electrophoretic particles are particles (polymer or colloid) having the property of moving by an electric field in a dispersion medium. In the present embodiment, white electrophoretic particles and black electrophoretic particles are stored in the microcapsule 102a. The black electrophoretic particles are particles made of a black pigment such as aniline black or carbon black, and are positively charged in this embodiment. The white electrophoretic particles are particles made of a white pigment such as titanium dioxide or aluminum oxide, and are negatively charged in this embodiment.

  The second substrate 103 includes a film 103a and a transparent common electrode layer 103b (second electrode) formed on the lower surface of the film 103a. The film 103a plays a role of sealing and protecting the electrophoretic layer 102, and is, for example, a polyethylene terephthalate film. The film 103a is transparent and has an insulating property. The common electrode layer 103b is made of a transparent conductive film such as an indium oxide film (ITO film), for example.

FIG. 3 is a diagram showing an equivalent circuit of the pixel 110. In this embodiment, in order to distinguish each scanning line 112, the scanning lines 112 shown in FIG. 1 are called 1, 2, 3,... (M−1), m-th row in order from the top. You may want to Similarly, in order to distinguish the data lines 114, the data lines 114 shown in FIG. 1 are called 1, 2, 3,..., (N−1), nth column in order from the left. There is a case.
FIG. 3 shows an equivalent circuit of the pixel 110 corresponding to the intersection of the scanning line 112 in the i-th row and the data line 114 in the j-th column. Since the configuration of the pixel 110 corresponding to the intersection of the other data line 114 and the scanning line 112 is the same as the configuration shown in the figure, the data line 114 in the i-th row and the scanning in the j-th column are representatively shown here. The equivalent circuit of the pixel 110 corresponding to the intersection with the line 112 will be described, and the description of the equivalent circuit of the other pixels 110 will be omitted.

  As shown in FIG. 3, each pixel 110 includes an n-channel thin film transistor (hereinafter simply referred to as “TFT”) 110a, a display element 110b, and an auxiliary capacitor 110c. In the pixel 110, the gate electrode of the TFT 110a is connected to the scanning line 112 in the i-th row, the source electrode is connected to the data line 114 in the j-th column, and the drain electrode is a pixel that is one end of the display element 110b. The electrode 101d is connected to one end of the auxiliary capacitor 110c. The auxiliary capacitor 110c has a configuration in which a dielectric layer is sandwiched between a pair of electrodes formed on the circuit layer 101c. The electrode at the other end of the auxiliary capacitor 110c is set to a common voltage across the pixels. The pixel electrode 101d faces the common electrode layer 103b, and the electrophoretic layer 102 including the microcapsules 102a is sandwiched between the pixel electrode 101d and the common electrode layer 103b. Therefore, the display element 110b has a capacity in which the electrophoretic layer 102 is sandwiched between the pixel electrode 101d and the common electrode layer 103b when viewed in an equivalent circuit. The display element 110b holds (stores) the voltage between both electrodes and performs display according to the direction of the electric field generated by the held voltage. In the present embodiment, a common voltage Vcom is applied to the other electrode of the auxiliary capacitor 110c of each pixel 110 and the common electrode layer 103b by an external circuit (not shown).

Returning to FIG. 1, the scanning line driving circuit 130 is connected to each scanning line 112 in the display region 100. The scanning line driving circuit 130 selects the scanning line 112 in the order of 1, 2,..., M-th row under the control of the controller 5, and a high level signal for the selected scanning line 112. , And a low level signal is supplied to the other scanning lines 112 that are not selected.
The data line driving circuit 140 is connected to each data line 114 in the display area, and the data line driving circuit 140 is connected to the data line 114 in each column according to the display content of one row of the pixels 110 connected to the selected scanning line 112. Each supplies a data signal.

In each period (hereinafter referred to as “frame period” or simply “frame”) after the scanning line driving circuit 130 selects the first scanning line 112 until the selection of the m-th scanning line 112 ends. The scanning line 112 is selected once, and a data signal is supplied to each pixel 110 once per frame.
When the scanning line 112 is at a high level, the TFT 110 a whose gate is connected to the scanning line 112 is turned on, and the pixel electrode 101 d is connected to the data line 114. When a data signal is supplied to the data line 114 when the scanning line 112 is at a high level, the data signal is applied to the pixel electrode 101d through the TFT 110a that is turned on. When the scanning line 112 becomes low level, the TFT 110a is turned off. However, the voltage applied to the pixel electrode 101d by the data signal is accumulated in the auxiliary capacitor 110c, and the potential of the pixel electrode 101d and the potential of the common electrode layer 103b. Electrophoretic particles move according to the potential difference (voltage).

  For example, when the voltage of the pixel electrode 101d is + 15V (second voltage) with respect to the voltage Vcom of the common electrode layer 103b, the negatively charged white electrophoretic particles move to the pixel electrode 101d side and become positive The charged black electrophoretic particles move to the common electrode layer 103b side, and the pixel 110 displays black. Further, when the voltage of the pixel electrode 101d is −15 V (first voltage) with respect to the voltage Vcom of the common electrode layer 103b, the positively charged black electrophoretic particles move to the pixel electrode 101d side and are negative. The charged white electrophoretic particles move to the common electrode layer 103b side, and the pixel 110 displays white. Note that the voltage of the pixel electrode 101d is not limited to the voltage described above. If the voltage is a positive (positive) voltage or a negative (negative) voltage with respect to the voltage Vcom of the common electrode layer 103b, the + 15V described above. Or a voltage other than −15V.

  In the present embodiment, when the display state of each pixel 110 is changed from white (low gradation) as the first gradation to black (high gradation) as the second gradation or from black to white, one frame is used. Instead of supplying the data signal only to the pixel 110 and changing the display state, the display state is changed by a writing operation for supplying the data signal to the pixel 110 over a plurality of frames. This is because when the display state is changed from white to black, even if a potential difference is applied to the electrophoretic particles for one frame, the black electrophoretic particles are not completely moved to the display side. This is because it must not. The same applies to white electrophoretic particles when the display state is changed from black to white. Therefore, for example, when the display state of the pixel 110 is changed from white to black, a data signal for displaying black on the pixel 110 is supplied to the pixel 110 over a plurality of frames, and the display state of the pixel 110 is changed from black to white. In the case of changing to (1), a data signal for displaying white on the pixel is supplied to the pixel 110 over a plurality of frames. In this specification, the “writing operation” refers to a data signal supply sequence to a pixel that is performed to change the display state of the pixel to a desired gradation display state, or the common electrode layer 103b and the pixel that are performed based on the data signal supply sequence A voltage application sequence between the electrodes 101d is said.

  In this embodiment, the pixel electrode 101d of the pixel 110 in one frame is a positive electrode whose potential is higher than that of the common electrode layer 103b, and the pixel electrode 101d of another pixel 110 in the same frame is the common electrode layer 103b. In contrast, a negative electrode having a lower potential can be obtained. That is, the driving is such that both the positive electrode and the negative electrode can be selected with respect to the common electrode layer 103b within one frame (hereinafter referred to as bipolar driving). More specifically, in one frame, the pixel electrode 101d of the pixel 110 that changes the gradation to the high gradation side (second gradation side) is the positive electrode, and the gradation is on the low gradation side (first gradation side). The pixel electrode 101d of the pixel 110 to be changed is a negative electrode. Note that when the black electrophoretic particles are negatively charged and the white electrophoretic particles are positively charged, the pixel electrode of the pixel 110 that changes the gradation to the high gradation side (second gradation side). 101d may be a negative electrode, and the pixel electrode 101d of the pixel 110 whose gradation is changed to the low gradation side (first gradation side) may be a positive electrode.

Next, each storage area provided in the RAM 4 will be described. FIG. 4 is a diagram showing a part of the pixels 110 in the display area 100 and each storage area corresponding to these pixels 110. Each storage area includes a storage area corresponding to each of the pixels 110 in m rows and n columns.
FIG. 4A shows the arrangement of the pixels 110. Pixel P (i, j) represents one pixel 110 in the i-th row and j-th column. The subscript i represents the row number of the pixel 110 arranged in the matrix, and the subscript j represents the column number.
FIG. 4B shows a buffer corresponding to each of the pixels shown in FIG. 4A in the VRAM 3. For example, the buffer A (i, j) is a storage area corresponding to the pixel P (i, j). Pixel data indicating the gradation of the pixel P (i, j) is written into the buffer A (i, j). Note that pixel data whose value is “0” is written when the pixel is black, and pixel data whose value is “5” is written when the pixel is white.

FIG. 4C is a diagram showing a storage area corresponding to each of the pixels shown in FIG. 4A in the counter storage area B. For example, the counter storage area B (i, j) is a storage area corresponding to the pixel P (i, j). In the counter storage area B (i, j), a value indicating the remaining number of application times when a voltage is applied to the pixel P (i, j) a plurality of times is written.
FIG. 4D is a diagram showing a storage area corresponding to each of the pixels shown in FIG. 4A in the scheduled image storage area E. For example, the scheduled image storage area E (i, j) is a storage area corresponding to the pixel P (i, j). In the scheduled image storage area E (i, j), pixel data of each pixel of the image to be displayed in the display area 100 is written.
FIG. 4E is a diagram showing a storage area of the voltage application number N_PRE. In the voltage application frequency N_PRE, the voltage application frequency when changing the gradation of the pixel is written. Since the number of times of voltage application to the pixel varies depending on the temperature as will be described later, the value of the voltage application number N_PRE is rewritten according to the temperature measured by the temperature sensor 6.

  Next, the configuration of the controller 5 will be described. FIG. 5 is a block diagram showing functions realized in the controller 5 of the present embodiment. In the controller 5, an adjustment unit 501, a writing unit 502, and a changing unit 503 are realized. The blocks realized in the controller 5 may be realized by hardware, or may be realized by providing a CPU in the controller 5 and executing a program by the CPU.

The writing unit 502 is a block that performs a writing operation for changing the gradation of a pixel to white or black. The writing unit 502 controls the scanning line driving circuit 130 and the data line driving circuit 140 to apply the second voltage for changing the pixel from white to black or the first voltage for changing the pixel from black to white over a plurality of frames. To change the gradation of the pixel to white or black.
The adjustment unit 501 is a block that converges the amount of charge held by the electrophoretic layer 102 to a predetermined amount of charge. The adjustment unit 501 controls the scanning line driving circuit 130 and the data line driving circuit 140 to apply the first voltage or the second voltage to the pixel so that the charge amount held by the electrophoretic layer 102 converges to a predetermined charge amount. Apply to.
The change unit 503 is a block that changes the number of times the voltage is applied when the writing unit 502 changes the gradation of the pixel. The changing unit 503 specifies the temperature detected by the temperature sensor 6 based on the signal output from the temperature sensor 6. Further, the changing unit 503 writes the number of times of application corresponding to the specified temperature in the RAM 4. When changing the gradation of the pixel, the writing unit 502 applies the first voltage or the second voltage by the number of times of application written in the RAM 4.

  In the present embodiment, the controller 5 changes the number of voltage application (number of frames) when changing the gradation of the pixel according to the temperature detected by the temperature sensor 6. In this embodiment, the number of times of voltage application is 6 times when the detected temperature is less than 15 ° C, 5 times when the detected temperature is 15 ° C or more and less than 20 ° C, and 4 when the detected temperature is 20 ° C or more and less than 30 ° C. If the temperature is 30 ° C. or higher, it is 3 times. For example, when the temperature detected by the temperature sensor 6 is 18 ° C., when the pixel is changed from white to black, a voltage of +15 V is applied five times, and when the pixel is changed from black to white, a voltage of −15 V is set to 5 Apply once. If the number of times that the positive voltage is applied to the pixel is the same as the number of times that the negative voltage is applied, there is a bias between the number of times that the positive voltage is applied to the pixel electrode 101d and the number of times that the negative voltage is applied to the pixel electrode 101d. It does not occur.

However, after applying the + 15V voltage to the pixel five times to make the pixel black, if the detected temperature is less than 15 ° C., the black pixel is set to white at a voltage of −15V six times. Will be applied. In this case, the number of times of applying a negative voltage is larger than the number of times of applying a positive voltage, and there is a bias between the number of times of applying a positive voltage and the number of times of applying a negative voltage. When such an operation is repeatedly performed, there is a risk that the bias is increased between the number of times of applying a positive voltage and the number of times of applying a negative voltage, and the pixel may deteriorate quickly. For this reason, it is preferable that no deviation occurs between the number of times of applying a positive voltage and the number of times of applying a negative voltage to the pixel. Here, in a certain pixel, when the number of times of applying a positive voltage is equal to the number of times of accumulation of a negative voltage, the amount of charge held in the electrophoretic layer 102 in that pixel is a predetermined amount of charge (in this case, It can be considered that the state has converged to 0). In other words, the state in which the amount of charge held by the electrophoretic layer 102 in a certain pixel converges to 0 means that the number of positive voltage applications and the number of negative voltage accumulations in that pixel are equal. Can do.
Therefore, in this embodiment, even if the temperature changes, the operation is performed so that there is no bias between the number of times of applying a positive voltage to the pixel and the number of times of applying a negative voltage. The operation will be described below.

(Operation example of the first embodiment)
6 to 10 are flowcharts showing the flow of processing performed by the controller 5, and FIG. 6 is a diagram showing the flow of processing performed by the controller 5 before the frame period. Prior to the frame period, the controller 5 first initializes variables i and j to 1 (steps SA1 and SA2). Next, the controller 5 determines whether the value of the buffer A (i, j) is the same as the value of the scheduled image storage area E (i, j). Here, if the value of the buffer A (i, j) and the value of the scheduled image storage area E (i, j) are the same (YES in step SA3), the controller 5 moves the process flow to step SA7.

  When the value of the buffer A (i, j) and the value of the scheduled image storage area E (i, j) are different (NO in step SA3), the controller 5 sets the value of the counter storage area B (i, j) to 0. Judge whether there is. Here, when the value of the counter storage area B (i, j) is not 0 (NO in step SA4), the controller 5 moves the flow of processing to step SA7. On the other hand, when the value of the counter storage area B (i, j) is 0 (YES in step SA4), the pixel gradation is changed from the current gradation to the gradation of the buffer A (i, j). The number of times of applying the necessary voltage is written in the counter storage area B (i, j) (step SA5). Here, the controller 5 sets the value of the voltage application count N_PRE in the counter storage area B (i, j). For example, when the value of the voltage application count N_PRE is 5, “5” is written in the counter storage area B (i, j).

  When step SA5 is completed, the controller 5 overwrites the value of the scheduled image storage area E (i, j) with the value of the buffer A (i, j) (step SA6). When the process of step SA6 ends, the controller 5 determines whether the value of the variable j is n in step SA7. If the value of the variable j is not n, the controller 5 increments the variable j and moves the process flow to step SA3. If the value of the variable j is n, the controller 5 determines whether the value of the variable i is m in step SA8. If the value of the variable i is not m, the controller 5 increments the variable i and moves the process flow to step SA2.

  Next, FIG. 7 is a diagram showing a flow of processing performed by the controller 5 in the frame period. In this process, the controller 5 first initializes variable i and variable j to 1 (steps SB1, SB2). Next, the controller 5 determines whether or not the value of the scheduled image storage area E (i, j) is zero. If the value of the scheduled image storage area E (i, j) is 0 (black) (YES in step SB3), the controller 5 performs the process shown in FIG. 8 in step SB4, and performs the scheduled image storage area E (i , J) is 5 (white) (NO in step S3), the process shown in FIG. 9 is performed in step SB5.

  In the process of FIG. 8, the controller 5 first determines whether the value of the counter storage area B (i, j) is zero. When the value of the counter storage area B (i, j) is not 0 (NO in step SC1), the controller 5 updates the value of the counter storage area B (i, j) (step SC2). Specifically, the controller 5 decrements the value of the counter storage area B (i, j). Then, the controller 5 controls the data line driving circuit 140 so that the j-th data line 114 is set to +15 V with respect to the voltage Vcom (step SC3). If the controller 5 determines YES in step SC1, the controller 5 sets the data line 114 in the jth column to 0 V with respect to the voltage Vcom (step SC4).

  Next, the processing of FIG. 9 will be described. In the process of FIG. 9, the controller 5 first determines whether the value of the counter storage area B (i, j) is zero. When the value of the counter storage area B (i, j) is not 0 (NO in step SD1), the controller 5 updates the value of the counter storage area B (i, j) (step SD2). Specifically, the controller 5 decrements the value of the counter storage area B (1, 1). Then, the controller 5 sets the data line 114 in the j-th column to −15V with respect to the voltage Vcom (step SD3). If the controller 5 determines YES in step SD1, the controller 5 sets the data line 114 in the j-th column to 0 V with respect to the voltage Vcom (step SD4).

  Returning to FIG. 7, the controller 5 determines whether the value of the variable j is n in step SB6. If the value of the variable j is not n, the controller 5 increments the variable j and moves the process flow to step SB3. Further, when the value of the variable j is n, the controller 5 drives the i-th scanning line (step SB7). Next, the controller 5 determines whether the value of the variable i is m in step SB8. If the value of the variable i is not m, the controller 5 increments the variable i and moves the process flow to step SB2. Moreover, the controller 5 complete | finishes the process of FIG. 7, when the value of the variable i is m.

FIG. 10 is a flowchart showing a flow of processing for aligning the number of times of applying a positive voltage and the number of times of applying a negative voltage to a pixel. The process of FIG. 10 is executed after the process of FIG. 6 before the frame period.
In this process, the controller 5 first determines whether all the values in the counter storage area B are zero. If all the values in the counter storage area B are not 0 (NO in step SE1), the controller 5 ends this process. When all the values in the counter storage area B are 0 (YES in step SE1), the controller 5 specifies the temperature measured by the temperature sensor 6 (step SE2), and determines the number of times of voltage application corresponding to the specified temperature. The number of times of application is N_NEW (step SE3). Next, the controller 5 determines whether the value of the voltage application number N_PRE is equal to the value of the voltage application number N_NEW. Here, when the value of the voltage application number N_PRE and the value of the voltage application number N_NEW are the same (YES in step SE4), the controller 5 ends the process of FIG.

When the value of the voltage application number N_PRE is different from the value of the voltage application number N_NEW (NO in step SE4), the controller 5 performs a process of aligning the positive voltage application number and the negative voltage application number to the pixel. Specifically, the controller 5 executes a process for making all the pixels white (step SE5). In this process, no voltage is applied to the white pixels at this time, and the voltage is applied only to the black pixels to make the gradations of all the pixels uniform, but when the pixels are changed from black to white. Is the value of the voltage application number N_PRE.
Next, the controller 5 rewrites the value of the voltage application number N_PRE to the value of the voltage application number N_NEW (step SE6). Then, the controller 5 executes the process of making all pixels black (step SE7), and then executes the process of making all pixels white (step SE8) again. Further, the controller 5 performs a process of updating each storage area (step SE9). In addition, the controller 5 performs the process shown in FIG. 6 as a process of step SE9.

  Next, an example of the operation when the temperature detected by the temperature sensor 6 changes will be described with reference to FIG. FIG. 11 is a diagram showing the contents of each storage area that changes over time. As an example, the contents of each storage area corresponding to the pixel P (1, 1) and the pixel P (1, 2) are shown. Yes. The contents of each storage area are values after the end of the frame period. FIG. 11 also shows the difference in the number of application times of the voltage that makes the pixel black (+15 V) and the voltage that makes the pixel white (−15 V), and the change in temperature. As for the difference in the number of times of application, when a positive voltage is applied to the pixel, the value is incremented, and when a negative voltage is applied, the value is decremented and the value is 0. In the pixel, the number of times of applying a positive voltage is the same as the number of times of applying a negative voltage.

  First, in the first frame and the second frame, the value of the counter storage area B is 0, and the writing operation is not performed on all the pixels. After the contents of the buffer A are rewritten by the control unit 2 before the start of the third frame, the controller 5 performs the process of FIG. 6 before the start of the frame period. Here, the value of the buffer A (1, 1) is 0, the value of the scheduled image storage area E (1, 1) is 5, and the buffer A (1, 1) and the scheduled image storage area E (1) , 1) are different (NO in step SA3), and the value of the counter storage area B (1, 1) is 0 (YES in step SA4), the controller 5 uses the counter storage area B (1, 1). Is set (step SA5).

  Here, when the value of the voltage application number N_PRE is 5, the controller 5 writes 5 in the counter storage area B (1, 1) as the voltage application number for setting the gradation to 0 (black). Further, the controller 5 overwrites the value of the scheduled image storage area E (1, 1) with the value of the buffer A (1, 1) to make it 0 (step SA6). Next, the controller 5 has a value of 5 in the buffer A (1, 2), a value of the scheduled image storage area E (1, 2) is 0, and the buffer A (1, 2) and the scheduled image storage area. Since the value of E (1,2) is different (NO in step SA3) and the value of the counter storage area B (1,2) is 0 (YES in step SA4), the controller 5 sets the gradation to 5 (white 5 is written in the counter storage area B (1,2) as the number of times of voltage application (step SA5), and the value of the scheduled image storage area E (1,2) is the value of the buffer A (1,2). Overwrite to 5 (step SA6).

  Next, the controller 5 executes the process of FIG. At this point, since there is an area in which 5 is written in the counter storage area B as described above, the controller 5 determines NO in step SE1 and ends the process of FIG. Next, the controller 5 executes the processing of FIG. 7 when the frame period comes.

In the process of FIG. 7, since the value of the scheduled image storage area B (1, 1) is 0 for the pixel P (1, 1), the controller 5 performs the process of step SB4 (the process of FIG. 8). Run. In the process of FIG. 8, since the value of the counter storage area B (1, 1) is not 0 (NO in step SC1), the controller 5 decrements the value of the counter storage area B (1, 1) to 4 (Step SC2). Further, the controller 5 sets the data line 114 in the first column to + 15V with respect to the voltage Vcom (step SC3), and moves the processing flow to step SB6.
For the pixel P (1,2), since the value of the scheduled image storage area B (1,2) is 5, the controller 5 executes the process of step SB5 (the process of FIG. 9). In the process of FIG. 9, since the value of the counter storage area B (1,2) is not 0 (NO in step SD1), the controller 5 decrements the value of the counter storage area B (1,2) to 4 (Step SD2). Further, the controller 5 sets the data line 114 in the first column to −15V with respect to the voltage Vcom (step SD3), and moves the processing flow to step SB6.
Thereafter, when the scanning line 112 in the first row is driven (step SB7), a voltage of + 15V with respect to the voltage Vcom is applied to the pixel electrode 101d of the pixel P (1,1), and black electrophoresis is performed. The particles move to the common electrode layer 103b side, a voltage of -15V is applied to the pixel electrode 101d of the pixel P (1,2) with respect to the voltage Vcom, and the white electrophoretic particles are moved to the common electrode layer 103b side. Moving.

  Up to the seventh frame thereafter, the process of step SB4 is performed for the pixel P (1,1), and the process of step SB5 is performed for the pixel P (1,2). When the seventh frame ends, the values of the counter storage area B (1, 1) and the counter storage area B (1, 2) become zero.

Next, if the contents of the buffer A have not been rewritten before the start of the eighth frame, since YES is determined in step SA3 for all pixels before the start of the frame period, the counter storage area B and the scheduled image storage area The contents of E are not updated.
Further, in the eighth frame, since all the values in the counter storage area B are 0, the controller 5 determines YES in step SE1 in the process of FIG. Next, the controller 5 identifies the temperature based on the signal from the temperature sensor 6 (step SE2), and identifies the number of times of voltage application N_NEW corresponding to the identified temperature (step SE3). Here, when the temperature specified in step SE2 is 19 ° C., the voltage application frequency N_NEW is 5 because the voltage application frequency is 5 when the temperature is 15 ° C. or higher and less than 20 ° C.

  Next, since the value of the voltage application number N_PRE is 5, which is the same as the value 5 of the voltage application number N_NEW, the controller 5 determines YES in step SE4 and ends the process of FIG. After that, when the frame period is reached, the value of the counter storage area B (1, 1) is 0 for the pixel P (1, 1), and therefore the controller 5 performs the process of step SC4, and the pixel P (1 , 2), since the value of the counter storage area B (1, 2) is 0, the process of step SD4 is performed. When the controller 5 executes the process of step SB7, the potential difference between the pixel electrode 101d and the common electrode layer 103b becomes 0 V in the pixel P (1,1) and the pixel P (1,2), and the electrophoretic particles Will not move.

Next, when the contents of the buffer A are not rewritten before the start of the ninth frame, the contents of the counter storage area B and the scheduled image storage area E are not updated as in the eighth frame. Since all the values in the counter storage area B are 0, the controller 5 determines YES in step SE1.
Next, the controller 5 identifies the temperature based on the signal from the temperature sensor 6 (step SE2), and identifies the number of times of voltage application N_NEW corresponding to the identified temperature (step SE3). Here, when the temperature has changed from the 8th frame and the temperature specified in step SE2 is 20 ° C., the voltage application frequency is 4 when the temperature is 20 ° C. or more and less than 30 ° C. N_NEW is 4. Since the value of the voltage application number N_PRE is 5, which is different from the value 4 of the voltage application number N_NEW, the controller 5 determines NO in Step SE4 and moves the process flow to Step SE5.

In step SE5, the controller 5 writes 5 in the area where 0 is written in the scheduled image storage area E. For the pixel in which the value of the scheduled image storage area E is rewritten from 0 to 5, the controller 5 sets the value of the counter storage area B to the value of the voltage application count N_PRE. For example, since 0 is written in the scheduled image storage area E (1, 1) at the end point of the eighth frame, the controller 5 rewrites the value of the scheduled image storage area E (1, 1) to 5. . Further, the controller 5 rewrites the value of the counter storage area B (1, 1) to 5 that is the value of the voltage application count N_PRE at this time.
Thereafter, the controller 5 repeats the processing of FIG. 7 until all the values in the counter storage area B become zero. As a result, for the pixel P (1, 1), the voltage of −15V is applied five times, the difference between the voltage application frequency of + 15V and the voltage application frequency of −15V becomes 0, and the voltage application frequency of + 15V is applied to all the pixels. And the difference in the number of applied voltages of -15V becomes zero. That is, the positive voltage application count and the negative voltage application count are aligned in all pixels.

Next, the controller 5 rewrites the value of the voltage application number N_PRE with the value of the voltage application number N_NEW (step SE6). Thereby, the value of the voltage application number N_PRE is rewritten from 5 to 4. Thereafter, the controller 5 executes a process for setting all pixels to black (step SE7). In step SE7, the controller 5 sets all the values in the scheduled image storage area E to zero. Further, all the values in the counter storage area B are set to the value of the voltage application number N_PRE. As a result, 4 is written in the counter storage area B (1, 1) and the counter storage area B (1, 2), and the scheduled image storage area E (1, 1) and the scheduled image storage area E (1, 2). 0 is written in.
Thereafter, the controller 5 repeats the processing of FIG. 7 until all the values in the counter storage area B become zero. As a result, the + 15V voltage is applied four times to all the pixels, and the difference between the + 15V voltage application count and the -15V voltage application count is 4.

Next, the controller 5 executes a process for making all pixels white (step SE8). In step SE8, the controller 5 sets all the values of the scheduled image storage area E to 5. Further, all the values in the counter storage area B are set to the value of the voltage application number N_PRE. As a result, 4 is written in the counter storage area B (1, 1) and the counter storage area B (1, 2), and the scheduled image storage area E (1, 1) and the scheduled image storage area E (1, 2). 5 is written in.
Thereafter, the controller 5 repeats the processing of FIG. 7 until all the values in the counter storage area B become zero. Accordingly, a voltage of −15 V is applied four times to all the pixels, and the difference between the number of times of applying the voltage of +15 V and the number of times of applying the voltage of −15 V becomes zero.

Next, the controller 5 performs the process of FIG. 6 in step SE9 to make the contents of the scheduled image storage area E the same as the contents of the buffer A for each pixel. Note that the contents of the buffer A (1, 1) are rewritten from 0 to 5 by the control unit 2 before the start of the tenth frame after the processing of FIG. If the content has been rewritten from 5 to 0, the value of the buffer A (1, 1) and the scheduled image storage area E (1, 1) are the same for the pixel P (1, 1). The controller 5 determines YES in step SA3, the value of the scheduled image storage area E (1, 1) remains 5, and the value of the counter storage area B (1, 1) remains 0. Further, for the pixel P (1,2), since the values of the buffer A (1,2) and the scheduled image storage area E (1,2) are different, the controller 5 determines NO in step SA3, and the scheduled image The value of the storage area E (1,2) is set to 0, and the value of the counter storage area B (1,2) is set to 4.
After that, when the frame period is reached, the process of FIG. 7 is executed, and a voltage of +15 V is applied to the pixel P (1,2) until the value of the counter storage area B (1,2) becomes 0, The gradation changes to black.

  As described above, in this embodiment, when changing the voltage application frequency for changing the gradation of the pixel according to the temperature, first, the voltage application frequency of +15 V and the voltage application frequency of −15 V are set. The voltage application count is changed after the alignment. Therefore, the polarity of the applied voltage and the number of times of application when the pixel is black are balanced with the polarity and the number of times of application of the voltage when the pixel is white, and the amount of charge held by the pixel becomes a constant value. Therefore, it is possible to prevent the pixels from deteriorating quickly.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment of the present invention is different from the first embodiment in the configuration of the RAM 4 and the flow of processing performed by the controller 5. Hereinafter, description of the same configuration as that of the first embodiment will be omitted, and differences will be described.

FIG. 12 is a diagram showing a configuration of the RAM 4 according to the present embodiment. As shown in the figure, in the present embodiment, a balance storage area D is provided. FIG. 13 is a diagram showing storage areas corresponding to the respective pixels shown in FIG. 4A in the balance storage area D. For example, the balance storage area D (i, j) is a storage area corresponding to the pixel P (i, j). The balance storage area D (i, j) stores the difference between the number of times of applying a positive voltage applied to the pixel P (i, j) and the number of times of applying a negative voltage.
In this embodiment, since the ease of movement in the dispersion medium differs between the white electrophoretic particles and the black electrophoretic particles, the number of times of voltage application when changing the gradation of the pixels It is different when changing from black to black and when changing the pixel from black to white.
Specifically, when the pixel is changed from black to white, when the temperature detected by the temperature sensor 6 is less than 15 ° C., it is 7 times, when the temperature is 15 ° C. or more and less than 20 ° C., 6 times, 20 ° C. or more and 30 ° C. If it is less than 5 times, it is 5 times, and if it is 30 ° C. or higher, it is 4 times. When the pixel is changed from white to black, when the temperature detected by the temperature sensor 6 is less than 15 ° C, it is 5 times, when it is 15 ° C or more and less than 20 ° C, it is 4 times, and when it is 20 ° C or more and less than 30 ° C. 3 times, and 3 times when the temperature is 30 ° C. or higher.

  In the present embodiment, the RAM 4 is provided with a first voltage application number N_PRE1 and a second voltage application number N_PRE2. In the first voltage application number N_PRE1, the voltage application number when the pixel is changed from black to white is written, and in the second voltage application number N_PRE2, the voltage application number when the pixel is changed from white to black is written.

  Next, processing performed by the controller 5 of the present embodiment will be described. First, in the present embodiment, the processing in FIG. 6 is performed before the frame period, but the content of the processing in step SA5 is different from that in the first embodiment. Specifically, in step SA5 of the present embodiment, the controller 5 counters the value of the first voltage application count N_PRE1 when the value of the scheduled image storage area E (i, j) is 5 (white). When the value of the scheduled image storage area E (i, j) is 0 (black), the value of the second voltage application number N_PRE2 is set to the counter storage area B (i, j). )

In the present embodiment, the process of FIG. 7 is performed, but the contents of the processes in steps SB4 and SB5 are different from those in the first embodiment.
FIG. 14 is a flowchart showing the flow of processing performed in step SB4 of the present embodiment. First, the controller 5 determines whether the value of the counter storage area B (i, j) is 0 in step SC11. If the value of the counter storage area B (i, j) is 0 (YES in step SC11), the j-th data line 114 is set to 0 V with respect to the voltage Vcom (step SC14). On the other hand, if the value of the counter storage area B (i, j) is not 0 (NO in step SC11), the values of the counter storage area B (i, j) and the balance storage area D (i, j) are set in step SC12. rewrite. Specifically, the controller 5 decrements the value of the counter storage area B (i, j) and increments the value of the balance storage area D (i, j). Note that the process of step SC13 is the same as the process of step SC3.

  Next, FIG. 15 is a flowchart showing the flow of processing performed in step SB5 of the present embodiment. First, the controller 5 determines whether the value of the counter storage area B (i, j) is 0 in step SD11. If the value of the counter storage area B (i, j) is 0 (YES in step SD11), the j-th data line 114 is set to 0 V with respect to the voltage Vcom (step SD14). On the other hand, if the value of the counter storage area B (i, j) is not 0 (NO in step SD11), the values of the counter storage area B (i, j) and the balance storage area D (i, j) are set in step SD12. rewrite. Specifically, the controller 5 decrements the value of the counter storage area B (i, j) and decrements the value of the balance storage area D (i, j). Note that the process of step SD13 is the same as the process of step SD3.

In the present embodiment, the process of FIG. 16 is executed between the process of FIG. 6 and the process of FIG. 7 instead of the process of FIG. In the process shown in FIG. 16, the process of step SE11 is the same as that of step SE1, and the process of step SE12 is the same as that of step SE2.
In step SE13, the controller 5 specifies the first voltage application number N_NEW1 and the second voltage application number N_NEW2 based on the temperature specified in step SE12. For example, when the temperature specified in step SE12 is 18 ° C., six times of voltage application times for changing the pixel from black to white are set as the first voltage application number N_NEW1, and 4 times of voltage application times for changing the pixel from white to black are set. The number of times is the second voltage application number N_NEW2.

Next, in step SE14, the controller 5 determines whether the first voltage application number N_NEW1 and the first voltage application number N_PRE1 are the same, and whether the second voltage application number N_NEW2 and the second voltage application number N_PRE2 are the same. to decide. Here, if the controller 5 determines YES, the process of FIG. 16 ends.
On the other hand, if NO is determined in step SE14, the controller 5 adjusts the balance between the polarity of the applied voltage and the number of times of application when the pixel is black and the polarity and the number of times of application of the voltage when the pixel is white. Is executed (step SE15). Specifically, the controller 5 writes 0 (black) to the scheduled image storage area D for the pixels whose balance storage area D value is negative, and stores the absolute value of the balance storage area D as a counter. Write to area B. Further, the controller 5 writes 5 (white) to the scheduled image storage area D for the pixels having a positive value in the balance storage area D, and stores the absolute value of the balance storage area D in the counter storage area B. Write. When the values of the scheduled image storage area E and the counter storage area B are changed, the controller 5 executes the process of FIG. 7 until the values of the counter storage areas B of all the pixels become zero.

  Next, in step SE16, the controller 5 sets the value of the first voltage application frequency N_PRE1 as the value of the first voltage application frequency N_NEW1, and sets the value of the second voltage application frequency N_PRE2 as the value of the second voltage application frequency N_NEW2. Thereafter, the controller 5 executes a process of setting all pixels to black (step SE17) and then executes a process of setting all pixels to white (step SE18). Further, the controller 5 performs a process of updating each storage area (step SE19). In addition, the controller 5 performs the process shown in FIG. 6 as a process of step SE19.

  Next, an example of the operation when the temperature detected by the temperature sensor 6 changes will be described with reference to FIG. FIG. 17 is a diagram showing the contents of each storage area that changes over time. As an example, the contents of each storage area corresponding to the pixel P (1,1) and the pixel P (1,2) are shown. Yes. The contents of each storage area are values after the end of the frame period. FIG. 17 also shows changes in the temperature detected by the temperature sensor 6, the value of the first voltage application number N_PRE1, and the value of the second voltage application number N_PRE2.

First, in the first frame and the second frame, the value of the counter storage area B is 0, and the writing operation is not performed on all the pixels. After the contents of the buffer A are rewritten by the control unit 2 before the start of the third frame, the controller 5 performs the process of FIG. 6 before the start of the frame period. Here, the value of the buffer A (1, 1) is 0, the value of the scheduled image storage area E (1, 1) is 5, and the buffer A (1, 1) and the scheduled image storage area E (1) , 1) are different (NO in step SA3), and the value of the counter storage area B (1, 1) is 0 (YES in step SA4), the controller 5 uses the counter storage area B (1, 1). Is set (step SA5).
Here, in the present embodiment, the content of the processing in step SA5 is different from that in the first embodiment. At this time, when the value of the second voltage application count N_PRE2 is 4, the controller 5 writes 4 in the counter storage area B (1, 1) as the voltage application count for setting the gradation to 0 (black). Further, the controller 5 overwrites the value of the scheduled image storage area E (1, 1) with the value of the buffer A (1, 1) to make it 0 (step SA6).

  Further, the controller 5 has a value of 5 in the buffer A (1, 2), a value of the scheduled image storage area E (1, 2) is 0, and the buffer A (1, 2) and the scheduled image storage area E. Since the values of (1, 2) are different (NO in step SA3), and the value of the counter storage area B (1, 2) is 0 (YES in step SA4), the controller 5 uses the counter storage area B (1, The value of 1) is set (step SA5). At this time, when the value of the first voltage application number N_PRE1 is 6, the controller 5 writes 6 in the counter storage area B (1, 2) as the voltage application number for setting the gradation to 5 (white). Then, the value of the scheduled image storage area E (1,2) is overwritten with the value of the buffer A (1,2) to 5 (step SA6).

  Next, the controller 5 executes the process of FIG. At this point, since there is an area in which a value other than 0 is written in the counter storage area B as described above, the controller 5 determines NO in step SE11 and ends the process of FIG. Next, the controller 5 executes the process of FIG. 7 when the frame period is reached.

In the process of FIG. 7, since the value of the scheduled image storage area B (1, 1) is 0 for the pixel P (1, 1), the controller 5 executes the process of step SB4 (process of FIG. 14). . In the process of FIG. 14, the controller 5 decrements the value of the counter storage area B (1, 1) by 3 because the value of the counter storage area B (1, 1) is not 0 (NO in step SC11). And the value of the balance storage area D (1, 1) is incremented (step SC12). Further, the controller 5 sets the data line 114 in the first column to + 15V with respect to the voltage Vcom (step SC13), and moves the processing flow to step SB6.
For the pixel P (1,2), the value of the scheduled image storage area B (1,2) is 5, so the controller 5 executes the process of step SB5 (the process of FIG. 15). In the process of FIG. 15, the controller 5 decrements the value of the counter storage area B (1,2) to 5 because the value of the counter storage area B (1,2) is not 0 (NO in step SD11). Then, the value of the balance storage area D (1, 2) is decremented (step SD12). Further, the controller 5 sets the data line 114 in the first column to −15 V with respect to the voltage Vcom (step SD13), and moves the processing flow to step SB6.
Thereafter, when the scanning line 112 in the first row is driven (step SB7), a voltage of + 15V with respect to the voltage Vcom is applied to the pixel electrode 101d of the pixel P (1,1), and black electrophoresis is performed. The particles move to the common electrode layer 103b side, a voltage of -15V is applied to the pixel electrode 101d of the pixel P (1,2) with respect to the voltage Vcom, and the white electrophoretic particles are moved to the common electrode layer 103b side. Moving.

Thereafter, the process of step SB4 is performed for the pixel P (1,1) until the value of the counter storage area B becomes 0, and the value of the counter storage area B is 0 for the pixel P (1,2). The process of step SB5 is performed up to the eighth frame. Next, when the contents of the buffer A are not rewritten at the time when the eighth frame is finished, YES is determined in step SA3 for all the pixels, so the contents of the counter storage area B and the scheduled image storage area E are not updated. .
Thereafter, the processing of FIG. 16 is executed. At this time, since the values of the counter storage area B are all 0, the controller 5 determines YES in step SE11. Next, the controller 5 specifies the temperature based on the signal from the temperature sensor 6 (step SE12), and specifies the first voltage application number N_NEW1 and the second voltage application number N_NEW2 corresponding to the specified temperature (step SE13). . When the temperature specified in step SE2 is 20 ° C., the first voltage application number N_NEW1 is 5, and the second voltage application number N_NEW2 is 3.

  Here, since the value of the first voltage application number N_PRE1 is different from the value of the first voltage application number N_NEW1, and the value of the second voltage application number N_PRE2 is different from the value of the second voltage application number N_NEW2, the controller 5 performs step SE14. Is determined as NO, and the flow of processing proceeds to step SE15.

In step SE5, since the value of the balance storage area D (1,1) is −2, the controller 5 writes 0 (black) in the scheduled image storage area D (1,1), and the balance storage area The absolute value 2 of the value of D is written into the counter storage area B (1, 1). Further, since the value of the balance storage area D (1,2) is -1, the controller 5 writes 0 (black) to the scheduled image storage area D (1,2), and the value of the balance storage area D 1 is written to the counter storage area B (1, 2).
Thereafter, the controller 5 repeats the processing of FIG. 7 until all the values in the counter storage area B become zero. As a result, the + 15V voltage is applied twice for the pixel P (1, 1), and the difference between the + 15V voltage application count and the −15V voltage application count is 0. For the pixel P (1, 2), The + 15V voltage is applied once, and the difference between the + 15V voltage application count and the -15V voltage application count becomes zero. That is, the positive voltage application count and the negative voltage application count are aligned in all pixels.

Next, the controller 5 rewrites the value of the first voltage application number N_PRE1 with the value of the first voltage application number N_NEW1, and rewrites the value of the second voltage application number N_PRE2 with the value of the second voltage application number N_NEW2 (step SE16).
Next, the controller 5 executes a process for making all pixels black (step SE17). In step SE17, the controller 5 sets all the values in the scheduled image storage area E to zero. Further, all the values in the counter storage area B are set to the value of the second voltage application count N_PRE2. As a result, 3 is written in the counter storage area B (1, 1) and the counter storage area B (1, 2), and the scheduled image storage area E (1, 1) and the scheduled image storage area E (1, 2). 0 is written in. Thereafter, the controller 5 repeats the processing of FIG. 7 until all the values in the counter storage area B become zero. As a result, the + 15V voltage is applied three times to all the pixels, and the difference between the + 15V voltage application count and the -15V voltage application count is 3.

  Next, the controller 5 executes a process for making all pixels white (step SE18). In step SE18, the controller 5 sets all the values of the scheduled image storage area E to 5. Further, all the values in the counter storage area B are set to the value of the first voltage application number N_PRE1. As a result, 5 is written in the counter storage area B (1,1) and the counter storage area B (1,2), and the scheduled image storage area E (1,1) and the scheduled image storage area E (1,2). 5 is written in. Thereafter, the controller 5 repeats the processing of FIG. 7 until all the values in the counter storage area B become zero. As a result, a voltage of −15 V is applied five times to all the pixels, and the difference between the number of times of applying the voltage of +15 V and the number of times of applying the voltage of −15 V is −2.

  Next, the controller 5 performs the process of FIG. 6 in step SE19 to make the contents of the scheduled image storage area E the same as the contents of the buffer A for each pixel. Note that the contents of the buffer A (1, 1) are rewritten from 0 to 5 by the control unit 2 before the start of the tenth frame after the processing of FIG. If the content has been rewritten from 5 to 0, the value of the buffer A (1, 1) and the scheduled image storage area E (1, 1) are the same for the pixel P (1, 1). The controller 5 determines YES in step SA3, the value of the scheduled image storage area E (1, 1) remains 5, and the value of the counter storage area B (1, 1) remains 0.

  Further, for the pixel P (1,2), since the values of the buffer A (1,2) and the scheduled image storage area E (1,2) are different, the controller 5 determines NO in step SA3, and the scheduled image. The value of the storage area E (1,2) is set to 0, and the value of the counter storage area B (1,2) is set to 3. After that, when the frame period is reached, the process of FIG. 7 is executed, and a voltage of +15 V is applied to the pixel P (1,2) until the value of the counter storage area B (1,2) becomes 0, The gradation changes to black.

  As described above, in this embodiment, when changing the voltage application frequency for changing the gradation of the pixel according to the temperature, first, in step SE15, the voltage application frequency of + 15V and the voltage application voltage of -15V are applied. The number of times of voltage application is changed after aligning the number of times. Therefore, the polarity of the applied voltage and the number of times of application when the pixel is black are balanced with the polarity and the number of times of application of the voltage when the pixel is white, and the amount of charge held by the pixel becomes a constant value. Therefore, it is possible to prevent the pixels from deteriorating quickly.

[Electronics]
Next, an example of an electronic apparatus to which the display device 1000 according to the above-described embodiment is applied will be described. FIG. 18 is a diagram illustrating an appearance of an electronic book reader using the display device 1000 according to the above-described embodiment. The electronic book reader 2000 includes a plate-shaped frame 2001, buttons 9A to 9F, the electro-optical device 1, the control unit 2, the VRAM 3, and the RAM 4 according to the above-described embodiment. In the electronic book reader 2000, the display area 100 is exposed. In the electronic book reader 2000, the contents of the electronic book are displayed in the display area 100, and the pages of the electronic book are turned by operating the buttons 9A to 9F. In addition, examples of the electronic apparatus to which the electro-optical device 1 according to the above-described embodiment can be applied include a watch, electronic paper, an electronic notebook, a calculator, a mobile phone, and the like.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows. In addition, you may combine each of embodiment mentioned above and the following modifications.

  In the above-described embodiment, the electro-optical device having the electrophoretic layer 102 has been described as an example. However, the present invention is not limited to this. The electro-optical device is not limited as long as writing for changing the display state of a pixel from the first display state to the second display state is performed by a writing operation in which a voltage is applied a plurality of times. For example, an electro-optical device using an electronic powder fluid as an electro-optical material may be used.

  In the present invention, when changing the number of times of voltage application, the polarity of the applied voltage and the number of times of application when the pixel is made black can be balanced with the polarity and the number of times of application of the voltage when the pixel is made white. An image may be displayed. For example, in the first embodiment described above, the controller 5 changes the gradation of all pixels to white in step SE5, but changes the gradation of all pixels to white after changing the gradation of all pixels to black. Then, the processing after step SE6 may be performed. In the case of this configuration, the controller 5 may not perform the processing of step SE7 and step SE8. Further, the controller 5 may perform the processing from step SE6 onward after performing the operations of white for all pixels, black for all pixels, and white for all pixels.

  In the embodiment described above, the black electrophoretic particles are positively charged and the white electrophoretic particles are negatively charged. However, the white electrophoretic particles are positively charged and the black electrophoretic particles are negatively charged. It may be configured to be electrically charged. In the case of this configuration, the controller 5 of the first embodiment executes the process of step SB5 when the value of the scheduled image storage area E (i, j) is 0 in step SB3, and executes the scheduled image storage area E ( If the value of i, j) is 5, the process of step SB4 is executed. In this configuration, the controller 5 of the first embodiment executes a process for making all pixels black in step SE5, performs a process for making all pixels white in step SE7, and performs all pixels in step SE8. In step SE5, the process of setting all pixels to black is executed. In step SE7, the process of setting all pixels to white is executed. You may make it perform the process of step SE9.

  In the first embodiment described above, the controller 5 may perform step SE9 without performing step SE8 after step SE7. Further, in the second embodiment, the controller 5 may perform the process of step SE19 without performing the process of step SE18 after step SE17.

  In the first embodiment described above, the controller 5 sets the contents of the scheduled image storage area E to be the same as the contents of the buffer A in step SE9, but is not limited to this configuration. The controller 5 may write an image obtained by inverting the black and white of the image written in the buffer A in step SE9 in the scheduled image storage area E. For example, in the case of the example in FIG. In this case, 0 is written in the scheduled image storage area E (1,1), and 5 is written in the scheduled image storage area E (1,2). Further, 4 is written in the counter storage area B (1, 1) and the counter storage area B (1, 2).

  In the above-described embodiment, in the writing operation for changing the gradation of the pixel, the voltage having the same polarity is applied over a plurality of frames. However, the configuration for changing the gradation of the pixel is limited to this configuration. It is not something. For example, in the first embodiment, when the pixel is black and the temperature is 25 ° C., the voltage of +15 V is applied four times, but the positive voltage is applied four times more than the negative voltage. It is sufficient if there are many configurations, and a voltage may be applied in the order of + 15V, +15, −15V, + 15V, + 15V, and + 15V, and a positive voltage and a negative voltage may be applied. In addition, when the pixel is white and the temperature is 25 ° C., a voltage of −15 V is applied four times. However, the number of negative voltage applications may be four times greater than the number of positive voltage applications. -15V, -15, + 15V, -15V, -15V, and -15V may be applied in this order, and a positive voltage and a negative voltage may be applied. In this modification, the difference between the number of times of applying a positive voltage and the number of times of applying a negative voltage when the pixel is black, and the number of times of applying a negative voltage and the positive voltage when the pixel is white. It is preferable that the difference from the number of times of application is the same.

In the above-described embodiment, when a voltage is applied to a pixel at a predetermined number of times in each temperature zone, the gradation of the pixel is changed to black or white and a two-gradation display is performed. When a smaller number of voltages are applied, some of the black electrophoretic particles are located between the pixel electrode 101d and the common electrode layer 103b, and an intermediate gradation can be displayed. For example, in the first embodiment, when the temperature detected by the temperature sensor 6 is less than 15 ° C., if the number of times the voltage is applied to the pixel is fixed to 6, the image is displayed in two gradations, and the gradation to be displayed When the number of times of voltage application is set to 1 to 6 according to the above, intermediate gradation display is performed.
In the present invention, using this, a mode in which the number of applied voltages is fixed to a predetermined number and a display of two gradations is performed, and a display of the intermediate gradation is performed by determining the number of applied voltages according to the intermediate gradation. The mode may be selected, and the display of the image may be switched between the display of the two gradations and the display of the intermediate gradation.
In this configuration, when switching from two-gradation display to intermediate gradation display and when switching from intermediate gradation display to two-gradation display, all the processes executed in the above-described embodiment are performed. The display may be switched after a process of aligning the number of times of applying a positive voltage and the number of times of applying a negative voltage for a pixel.

In the above-described embodiment, when a voltage is applied to the pixel at a predetermined number of times in each temperature zone, the gradation of the pixel is changed to black or white and a two-gradation display is performed. When a voltage is applied, a predetermined gradation is not obtained, but two gradations of gray close to black and gray close to white can be displayed. In this way, when the voltage is applied a smaller number of times than the predetermined number of times, the number of times of voltage application is small, so that the time required for displaying an image can be shortened.
In the present invention, this is utilized to display black and white in two gradations with a predetermined number of voltage applications, and with a gray level close to black with a voltage application number less than this predetermined number. It is also possible to select a case where two-tone display of gray close to white is performed.
In this configuration, when the number of times of voltage application is set to a predetermined number of times and when the number of times of voltage application is less than the predetermined number of times, a positive voltage is applied to all pixels, which is a process executed in the above-described embodiment. It is also possible to change the number of voltage applications after performing the process of making the number of application times equal to the number of negative voltage applications.

  Further, in the present invention, the controller 5 of the first embodiment may execute the process shown in FIG. 19 every time a predetermined time (for example, 15 minutes or 30 minutes) elapses. In the process of FIG. 19, the controller 5 first waits until all the values in the counter storage area B become 0 in step SF1. When controller 5 determines YES in step SF1, it performs steps SF2 to SF4. Note that the processing of step SF2 to step SF3 is the same as the processing of step SE2 to step SE3, and the processing of step SF4 is the same as the processing of step SE5.

  Next, the controller 5 performs the process of step SF5. Note that the process of step SF5 is the same as the process of step SE4. If the controller 5 determines NO in step SF5, the controller 5 performs steps SF6 to SF9. Steps SF6 to SF9 are the same as steps SE6 to SE9. If the controller 5 determines YES in step SF5, it moves the process flow to step SF7. Note that when the process of FIG. 19 is executed, the controller 5 may not execute the process of FIG. 6 before the frame period.

  In the second embodiment of the present invention, the processing shown in FIG. 20 may be executed every time a predetermined time (for example, 15 minutes or 30 minutes) elapses. In the process of FIG. 20, the controller 5 first waits until all the values in the counter storage area B become 0 in step SG1. If the controller 5 determines YES in step SG1, the controller 5 performs steps SG2 to SG4. Note that the processing of step SG2 to step SG3 is the same as the processing of step SE12 to step SE13, and the processing of step SG4 is the same as the processing of step SE15.

  Next, the controller 5 performs the process of step SG5. Note that the process of step SG5 is the same as the process of step SE14. If controller 5 determines NO in step SG5, controller 5 performs steps SG6 to SG9. In addition, the process of step SG6-step SG9 is the same as the process of step SE16-step SE19. If the controller 5 determines YES in step SG5, it moves the process flow to step SG7. In the second embodiment, when the process of FIG. 20 is executed, the controller 5 may not execute the process of FIG. 16 before the frame period.

DESCRIPTION OF SYMBOLS 1 ... Electro-optical device, 2 ... Control part, 3 ... VRAM, 4 ... RAM, 5 ... Controller, 6 ... Temperature sensor, 9A-9F ... Button, 10 ... Display part, 100 ... Display area, 101 ... 1st board | substrate, 101a ... substrate 101b ... adhesive layer 101c ... circuit layer 101d ... pixel electrode 102 ... electrophoretic layer 102a ... microcapsule 102b ... binder 103 ... second substrate 103a ... film 103b ... common electrode layer DESCRIPTION OF SYMBOLS 110 ... Pixel, 110a ... TFT, 110b ... Display element, 110c ... Auxiliary capacitor, 112 ... Scan line, 114 ... Data line, 501 ... Adjustment part, 502 ... Writing part, 503 ... Change part, 2000 ... Electronic book reader, 2001 ... Frame, A (i, j) ... Buffer, B, B (i, j) ... Counter storage area, D, D (i, j) ... Balance notation Region, E, E (i, j) ... planned image storage area, N_PRE ... number of voltage applications, N_PRE1 ... first voltage application times, N_PRE2 ... second voltage application times

Claims (11)

A plurality of first electrodes provided for each pixel; a second electrode disposed opposite to the plurality of first electrodes; and an electric power disposed between the plurality of first electrodes and the second electrode. A display device control device comprising: an optical material;
When changing the gradation of the pixel from the second gradation to the first gradation, a first writing operation is performed in which a first voltage is applied to the first electrode of the pixel a plurality of times, When the gradation is changed from the first gradation to the second gradation, a second voltage having a polarity different from that of the first voltage is applied to the first electrode of the pixel a plurality of times. A writing unit for performing a writing operation;
When changing the number of times of applying the first voltage in the first writing operation and the number of times of applying the second voltage in the second writing operation, the potential of the first electrode and the potential of the second electrode are the same potential. An adjustment unit that applies a voltage to the first electrode of at least one of the pixels so that the amount of charge held by the electro-optical material in the state converges to a predetermined amount of charge;
When changing the number of times of application of the first voltage and the number of times of application of the second voltage, the first and second voltages are applied in a state where the amount of charge held by the electro-optic material of each pixel converges to a predetermined amount of charge. A control device for a display device, comprising: a first voltage application frequency in the write operation; and a changing unit that changes the second voltage application frequency in the second write operation. After the changing unit changes the number of times of applying the first voltage and the number of times of applying the second voltage, the gradation of the plurality of pixels is changed to the first gradation or the second gradation. The control apparatus of the display apparatus of Claim 1. After the amount of charge held by the electro-optic material of each pixel is converged to a predetermined amount of charge by the adjustment unit, the gradation of the plurality of pixels is changed to the first gradation or the second gradation. The display device control device according to claim 1, wherein In the first write operation, the second voltage is applied in addition to the first voltage, and the number of times the first voltage is applied is greater than the number of times the second voltage is applied.
In the second write operation, the first voltage is applied in addition to the second voltage, and the number of times the second voltage is applied is greater than the number of times the first voltage is applied.
The difference between the number of times of application of the first voltage and the number of times of application of the second voltage in the first write operation is the difference between the number of times of application of the second voltage and the number of times of application of the first voltage in the second write operation. The display device control device according to claim 1, wherein the difference is equal to the difference between the display device and the display device. The number of times of application of the first voltage in the first write operation is the same as the number of times of application of the second voltage in the second write operation. The display device control apparatus according to one item. 4. The number of times of application of the first voltage in the first write operation is different from the number of times of application of the second voltage in the second write operation. 5. A control device for the display device according to 1. The number of times of application of the first voltage and the number of times of application of the second voltage are changed when the temperature detected by the sensor for detecting temperature changes. A control device for the display device according to 1. The mode can be switched between a mode in which the number of gradations displayed on the pixel is two gradations of the first gradation and the second gradation and a mode in which the number of gradations exceeds the two gradations.
The display according to any one of claims 1 to 7, wherein the changing unit changes the number of times of application of the first voltage and the number of times of application of the second voltage when the mode is switched. Control device for the device. A plurality of first electrodes provided for each pixel; a second electrode disposed opposite to the plurality of first electrodes; and an electric power disposed between the plurality of first electrodes and the second electrode. A control method for a display device comprising: an optical material;
When changing the gradation of the pixel from the second gradation to the first gradation, a first writing operation is performed in which a first voltage is applied to the first electrode of the pixel a plurality of times, When the gradation is changed from the first gradation to the second gradation, a second voltage having a polarity different from that of the first voltage is applied to the first electrode of the pixel a plurality of times. A write step for performing the write operation;
When changing the number of times of applying the first voltage in the first writing operation and the number of times of applying the second voltage in the second writing operation, the potential of the first electrode and the potential of the second electrode are the same potential. An adjusting step of applying a voltage to the first electrode of at least one of the pixels so that the amount of charge held by the electro-optic material in the state converges to a predetermined amount of charge;
When changing the number of times of application of the first voltage and the number of times of application of the second voltage, the first and second voltages are applied in a state where the amount of charge held by the electro-optic material of each pixel converges to a predetermined amount of charge. And a changing step of changing the number of times of application of the second voltage in the second writing operation. A plurality of first electrodes provided for each pixel; a second electrode disposed opposite to the plurality of first electrodes; and an electric power disposed between the plurality of first electrodes and the second electrode. A display device comprising: an optical material;
When changing the gradation of the pixel from the second gradation to the first gradation, a first writing operation is performed in which a first voltage is applied to the first electrode of the pixel a plurality of times, When the gradation is changed from the first gradation to the second gradation, a second voltage having a polarity different from that of the first voltage is applied to the first electrode of the pixel a plurality of times. A writing unit for performing a writing operation;
When changing the number of times of applying the first voltage in the first writing operation and the number of times of applying the second voltage in the second writing operation, the potential of the first electrode and the potential of the second electrode are the same potential. An adjustment unit that applies a voltage to the first electrode of at least one of the pixels so that the amount of charge held by the electro-optical material in the state converges to a predetermined amount of charge;
When changing the number of times of application of the first voltage and the number of times of application of the second voltage, the first and second voltages are applied in a state where the amount of charge held by the electro-optic material of each pixel converges to a predetermined amount of charge. And a changing unit that changes the number of times of application of the first voltage in the writing operation and the number of times of application of the second voltage in the second writing operation.   An electronic device comprising the display device according to claim 10.

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