JP6102373B2 - Control device, electro-optical device, electronic apparatus, and control method - Google Patents

Description

  The present invention relates to a technique for controlling a display element having memory properties.

  Patent Document 1 discloses a technique for displaying four gradations of black, dark gray, light gray, and white in an electrophoretic display device. In this display device, when the pixel is dark gray, the pixel is changed to black and then transitioned to dark gray. When the pixel is changed to light gray, the pixel is changed to white and then transitioned to light gray. Patent Document 1 discloses a configuration using a pulse width modulation driving method as a pixel driving method. By controlling the application time and polarity of a driving voltage applied to the pixel, the gradation of the pixel is disclosed. Is controlling.

Special table 2007-513368 gazette

  In the display device of Patent Document 1, when the gradation is changed from black to dark gray, the transition is made directly from black to dark gray. However, when the gradation is changed from black or dark gray to light gray, the pixel is changed to white. It has been changed to light gray. In other words, when changing the gradation from lower than light gray to light gray, since the gradation is once raised and then lowered, the pixel gradation changes during image rewriting. It will stand out.

  The present invention has been made in view of the above-described circumstances, and one of its purposes is to prevent changes in pixel gradation from being noticeable when rewriting an image.

In order to achieve the above object, a control device according to the present invention includes a first electrode provided for each of a plurality of pixels, a second electrode disposed to face the first electrode, and the first electrode. An electro-optic device having a memory property disposed between the second electrode and the second electrode, and having a gradation control unit for rewriting an image displayed by the pixel, When rewriting the image, the gradation control unit changes the gradation of the pixel to the second reference gradation side when the gradation after the rewriting is on the second reference gradation side of the gradation before the rewriting. A voltage to be applied is applied to the first electrode by the number of times applied according to the gradation difference between the gradation before rewriting and the gradation after rewriting, and the gradation after rewriting is a first reference than the gradation before rewriting. For a pixel on the gradation side, change the gradation of the pixel to the second reference gradation After that, the first electrode is changed to the first reference gradation, and then the voltage for changing the gradation of the pixel to the second reference gradation is applied by the number of times corresponding to the rewritten gradation. The structure which applies to is provided.
According to this configuration, for the pixel whose gradation is changed from the first reference gradation side to the second reference gradation side, the gradation changes without passing through the second reference gradation, and therefore the second reference gradation is changed. Compared with a configuration via a tone, a change in pixel gradation is less noticeable during image rewriting.

In the control device, the gradation control unit may be configured such that the voltage of the first electrode is set to the voltage of the second electrode for pixels whose gradation does not change before and after rewriting.
According to this configuration, since the voltage for changing the gradation of the pixel is not applied to the pixel whose gradation does not change before and after the rewriting, the change in the gradation of the pixel becomes inconspicuous during the rewriting of the image. .

In the control device, the first voltage for changing the gradation of the pixel to the first reference gradation side and the second voltage for changing the gradation of the pixel to the second reference gradation side are: The first voltage and the second voltage may have a predetermined polarity, and the polarities may be different from each other.
According to this configuration, the gradation of the pixel can be controlled by controlling the number of times the voltage is applied to the first electrode.

Further, in the control device, a phase in which the first voltage is applied to the first electrode and a phase in which the second voltage is applied to the first electrode during a period when the gradation control unit rewrites an image. It is good also as a structure with.
According to this configuration, in the same phase, the pixel to which the first voltage is applied and the pixel to which the second voltage is applied are not mixed, so that the amplitude of the data line can be suppressed, and as a result, power consumption is reduced. be able to.

Further, in the control device, when the voltage for changing the gradation to the second reference gradation side is applied to the pixel of the first reference gradation, the change amount of the gradation is the gradation as the first reference gradation. The voltage may be smaller than the amount of change in gradation when the voltage for changing the gradation toward the gradation side is applied to the pixel of the second reference gradation.
According to this configuration, it is easy to control halftone gradation.

In the control device, the second reference gradation may be a background color of a displayed image.
According to this configuration, since the number of pixels passing through the second reference gradation is reduced when the image is rewritten, the change in the pixel gradation becomes inconspicuous during the image rewriting.

In addition, the control device of the present invention includes a first electrode provided for each of a plurality of pixels, a second electrode disposed to face the first electrode, and a gap between the first electrode and the second electrode. An electro-optical material having a memory property, and a gradation control unit that rewrites an image displayed by the pixel, wherein the gradation control unit includes: In the case of rewriting an image, for a pixel whose gradation after rewriting is on the second reference gradation side with respect to the gradation before rewriting, a voltage for changing the gradation of the pixel to the second reference gradation side is set to the voltage before rewriting. With respect to a pixel that is applied to the first electrode for an application time corresponding to the gradation difference between the gradation and the gradation after rewriting, and the gradation after rewriting is on the first reference gradation side of the gradation before rewriting. , After changing the gradation of the pixel to the second reference gradation, After changing to the voltage of changing the gradation of the pixel to the second reference gradation side, at application time corresponding to the gradation after rewriting has a structure to be applied to the first electrode.
According to this configuration, for the pixel whose gradation is changed from the first reference gradation side to the second reference gradation side, the gradation changes without passing through the second reference gradation, and therefore the second reference gradation is changed. Compared with a configuration via a tone, a change in pixel gradation is less noticeable during image rewriting.

The electro-optical device according to the invention includes a first electrode provided for each of a plurality of pixels, a second electrode disposed to face the first electrode, the first electrode, and the second electrode. An electro-optical device having a memory property disposed between the two, and having a gradation control unit that rewrites an image displayed by the pixels, and the gradation control unit includes the image For a pixel whose gradation after rewriting is on the second reference gradation side with respect to the gradation before rewriting, a voltage for changing the gradation of the pixel to the second reference gradation side is set to a level before rewriting. With respect to a pixel that is applied to the first electrode with the number of times of application corresponding to the tone difference between the tone and the tone after rewriting, and the tone after rewriting is closer to the first reference tone than the tone before rewriting, The first reference gradation after the gradation of the pixel is changed to the second reference gradation After changing the voltage to change the tone of the pixel to the second reference gradation side, at the applied number of times corresponding to the gradation after rewriting has a structure to be applied to the first electrode.
According to this configuration, for the pixel whose gradation is changed from the first reference gradation side to the second reference gradation side, the gradation changes without passing through the second reference gradation, and therefore the second reference gradation is changed. Compared with a configuration via a tone, a change in pixel gradation is less noticeable during image rewriting.

  The present invention can be conceptualized not only as a control device and an electro-optical device, but also as a control method of the electro-optical device and an electronic apparatus having the electro-optical device.

The figure which showed the hardware constitutions of the display apparatus 1000. 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 which showed the structure of the controller 5. FIG. The figure which showed the structure of the storage area. The figure which showed an example of the table which LUT503 of 1st Embodiment has. The figure which showed an example of the table which LUT503 of 1st Embodiment has. The figure for demonstrating operation | movement of 1st Embodiment. The figure for demonstrating operation | movement of 1st Embodiment. The figure for demonstrating operation | movement of 1st Embodiment. The figure for demonstrating operation | movement of 1st Embodiment. The figure which showed an example of the table which LUT503 of 2nd Embodiment has. The figure which showed an example of the table which LUT503 of 2nd Embodiment has. The figure for demonstrating operation | movement of 2nd Embodiment. The figure for demonstrating operation | movement of 2nd Embodiment. The figure for demonstrating operation | movement of 2nd Embodiment. The figure for demonstrating operation | movement of 2nd Embodiment. The external view of the electronic book reader 2000. FIG.

[First Embodiment]
(Configuration of the first 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 and a control unit 2. The electro-optical device 1 includes a display unit 10 and a controller 5.

The control unit 2 is a microcomputer that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM, and the like, and controls the controller 5. In addition, the control unit 2 acquires image data indicating an image to be displayed in the display area 100 from a recording medium (not shown) and supplies the controller 5 with the image data.
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.

  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 between 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 with m rows × 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 a pixel electrode 101d (first electrode) corresponding to each intersection of the scanning line 112 and the data line 114.

  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 110 c is set to a common voltage across the pixels 110. 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 capacitance 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 acquires data indicating the voltage applied to the pixel electrode 101 d of the pixel 110 connected to the selected scanning line 112 from the controller 5. . The data line driving circuit 140 supplies data signals to the data lines 114 in each column according to the acquired data.

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 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 the positively charged black The 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 −15V 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 negatively charged. The 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, the data signal is not supplied to the pixel 110 for one frame and the display state is changed, but the data signal is supplied to the pixel 110 over a plurality of frames. The display state is changed by supplying. For example, when the display state of the pixel 110 is changed from white (W) to black (B), a data signal for displaying black on the pixel 110 is supplied to the pixel 110 over a plurality of frames. Is changed from black to white, a data signal for displaying white on the pixel 110 is supplied to the pixel 110 over a plurality of frames. In this embodiment, by utilizing the fact that even if a potential difference is applied to the electrophoretic particles for one frame, it does not become black or white, by controlling the number of times a voltage of +15 V or −15 V is applied to the pixel electrode 101d, Dark gray (DG) and light gray (LG) are displayed.

Next, the configuration of the controller 5 will be described. FIG. 4 is a block diagram showing the configuration of the controller 5 of the present embodiment. The controller 5 includes a RAM 501, a gradation control unit 502, and an LUT 503.
The RAM 501 is provided with a storage area for storing a frame number for managing which frame is controlled in each phase to be described later.
In addition, the RAM 501 is provided with a first storage area for storing image data supplied from the control unit 2 and a second storage area for storing image data of the displayed image. Each storage area has a storage area (buffer) for each pixel 110 arranged in m rows × n columns. 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 RAM 501. When the display of the image corresponding to the image data stored in the first storage area is completed, the image data stored in the second storage area is overwritten with the image data stored in the first storage area.

FIG. 5 is a diagram showing a part of the pixels 110 in the display area 100 and each storage area corresponding to these pixels 110. FIG. 5A 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. 5B is a diagram showing a buffer corresponding to each of the pixels 110 shown in FIG. 5A in the first storage area, and FIG. 5C is a diagram showing the second storage area. FIG. 6 shows a buffer corresponding to each of the pixels 110 shown in FIG.
For example, the buffer A (i, j) in the first storage area is a storage area corresponding to the pixel P (i, j). Pixel data indicating the gradation to be displayed on the pixel P (i, j) is written into the buffer A (i, j). Note that pixel data having a value “0” is written when the pixel 110 is black, and pixel data having a value “3” is written when the pixel 110 is white. When the pixel 110 is dark gray, pixel data having a value “1” is written, and when the pixel 110 is light gray, pixel data having a value “2” is written. The buffer B (i, j) in the second storage area is a storage area corresponding to the pixel P (i, j). Pixel data indicating the gradation displayed by the pixel P (i, j) is written into the buffer B (i, j).
Note that the RAM 501 is not limited to the configuration built in the controller 5 but may be a configuration externally attached.

The LUT 503 is a look-up table (Look Up Table) that stores voltages applied to the pixel electrode 101d during the frame period when rewriting an image to be displayed. The gradation control unit 502 newly displays a new gradation (pixel data stored in the first storage area) by rewriting to the LUT 503 and an old gradation (stored in the second storage area) displayed before the rewriting. When a frame number or the like is input, a voltage to be applied to the pixel electrode 101d in the frame of the input frame number is output to the gradation control unit 502.
6 and 7 are diagrams illustrating examples of tables stored in the LUT 503 according to the present embodiment. 6 and 7, the data stored in the column of the frame number represents a voltage applied to the pixel electrode 101d in the frame, “+” represents a voltage of + 15V, and “−” represents −. It represents a voltage of 15V. Note that “0” indicates that the voltage Vcom is applied to the pixel electrode 101d and the potential difference between the pixel electrode 101d and the common electrode layer 103b is set to 0V. For example, with respect to a pixel in which the gradation before rewriting is black and the gradation after rewriting is white, the LUT 503 refers to the row “W” in FIG. The data in is output.

  The gradation control unit 502 is a block that controls the gradation of the pixel 110. The gradation control unit 502 controls the scanning line driving circuit 130 and the data line driving circuit 140, and applies the voltage Vcom, + 15V voltage, or −15V voltage to the pixel electrode 101d in the frame period, so that the level of the pixel 110 is increased. Control the key. Specifically, in the present embodiment, the gradation control unit 502 rewrites an image using the first phase, the second phase, and the third phase during a rewriting period in which the image is rewritten.

  The first phase is a phase in which the gradation is changed for pixels whose gradation before and after rewriting is different and the gradation before rewriting is other than white. In the present embodiment, the number of frames in the first phase is 13 frames. That is, when the number of the first frame when rewriting an image is 1, the first to 13th frames are the first phase.

  The second phase is a phase in which after the first phase, the gradation is changed to black for pixels whose gradation after rewriting is lower than the gradation before rewriting. In the present embodiment, the number of frames in the second phase is 13 frames. When the number of the first frame when rewriting an image is 1, the 14th to 26th frames are in the second phase.

  The third phase is a phase in which after the second phase, the gradation is changed for a pixel whose gradation after rewriting is lower than the gradation before rewriting and becomes light gray or dark gray after rewriting. In the present embodiment, the number of frames in the third phase is 5 frames. When the number of the first frame when rewriting an image is 1, the 27th to 31st frames are in the third phase.

  The control unit 2 outputs the image data to the controller 5 when rewriting the image in the display area 100. When the controller 5 acquires the image data output from the control unit 2, the controller 5 writes the acquired image data in the first storage area of the RAM 501. Note that the image data of the image displayed before the image data is acquired is written in the second storage area. The gradation control unit 502 starts image rewriting processing when new image data is written in the first storage area.

  In the image rewriting process, the gradation control unit 502 initializes a frame number for managing which frame is controlled to 1 to control the gradation of the pixel 110 over a plurality of frames. The gradation control unit 502 initializes the frame number and then acquires pixel data in the first storage area and the second storage area.

  The gradation control unit 502 outputs the pixel data acquired from the first storage area and the second storage area and the frame number to the LUT 503. The LUT 503 refers to the tables of FIGS. 6 and 7 based on the pixel data and the frame number supplied from the gradation control unit 502, and outputs data indicating the voltage applied to the pixel electrode 101d. The gradation control unit 502 outputs a signal indicating a voltage to be applied to the pixel electrode 101 d to the data line driving circuit 140 in accordance with the data output from the LUT 503. When the data line driving circuit 140 outputs a data signal to the data line 114 based on this signal during the period when the scanning line 112 is selected, a voltage corresponding to the signal is applied to the pixel electrode 101d, and the gray level of the pixel Changes. The gradation control unit 502 adds 1 to the frame number every time one frame period ends, acquires data indicating the voltage to be applied to the pixel electrode 101d in the frame of the frame number after the addition from the LUT 503, and outputs the pixel 110 To control the gradation. When the 31st frame ends, the gradation control unit 502 ends the image rewriting process.

(Operation example of the first embodiment)
Next, an operation example when rewriting the gradation of a pixel in the first embodiment will be described. In the following description, when the gradation of the pixel before rewriting is black, the gradation of the pixel before rewriting is dark gray, the gradation of the pixel before rewriting is light gray, and the pixel before rewriting An example of the operation when the gradation of white is white will be described.

(Operation example when the gradation of the pixel before rewriting is black)
FIG. 8 is a diagram showing the transition of the gradation of pixels that were black before rewriting when the image was rewritten. FIG. 8A shows the case of black → white, and FIG. In the case of black → light gray, FIG. 8C shows the transition in the case of black → dark gray, and FIG. 8D shows the transition in the case of black → black. In FIG. 8 and FIGS. 9 to 11 described later, the horizontal axis is the frame number, and the vertical axis is the lightness (gradation) of the pixel. In FIG. 8 and FIGS. 9 to 11 to be described later, “(1)” in the figure indicates the first phase, “(2)” indicates the second phase, and “(3)” indicates the third phase. Show. In the present embodiment, in FIG. 8A, the gradation when the frame number is 0 is black (first reference gradation in the present embodiment), the gradation when the frame number is 2 is dark gray, The gradation when the number is 4 is light gray, and the gradation when the frame number is 12 is white (second reference gradation in the present embodiment).

First, the LUT 503 refers to the “W” row in the table of FIG. 6A for pixels whose gradation before rewriting is black and whose gradation after rewriting is white. In this row, since “−” is stored from the column of the frame number 1 to the column of 12, the LUT 503 outputs “−” from the first frame to the twelfth frame. When the gradation control unit 502 obtains “−” as data indicating the voltage applied to the pixel electrode 101d of the pixel, a signal instructing the voltage applied to the pixel electrode 101d of the pixel to be −15V is used as the data line. Output to the drive circuit 140. When the data line driving circuit 140 outputs a data signal to the data line 114 based on this signal, a voltage of −15 V is applied to the pixel electrode 101d of the pixel during the period when the scanning line 112 related to the pixel is selected. Then, as shown in FIG. 8A, the gradation of the pixel approaches white from the first frame and becomes white at the twelfth frame.
Also, “0” is stored in the column “W” in the table of FIG. When the gradation control unit 502 acquires “0” as data indicating the voltage applied to the pixel electrode 101d of the pixel, a signal that instructs the voltage Vcom to be applied to the pixel electrode 101d of the pixel is displayed on the data line. Output to the drive circuit 140. When the data line driving circuit 140 outputs a data signal to the data line 114 based on this signal, the voltage Vcom is applied to the pixel electrode 101d. Therefore, as shown in FIG. The gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 6A for pixels whose gradation before rewriting is black and whose gradation after rewriting is light gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 8, as shown in FIG. The gradation does not change. Further, since “-” is stored from the column of the frame number 9 to the column of 12 in the “LG” row of the table of FIG. 6A, as shown in FIG. The gray level of the pixel approaches white from the eyes, and becomes light gray at the 12th frame. In addition, since “0” is stored for the column with the frame number 13 and later in the row “LG” in the table of FIG. 6A, the gradation of the pixel does not change after the 13th frame. It will be.

  Next, the LUT 503 refers to the row of “DG” in the table of FIG. 6A for pixels whose gradation before rewriting is black and whose gradation after rewriting is dark gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 10, as shown in FIG. The gradation does not change. In addition, since “−” is stored in the column of the frame number 11 and the column of 12 in the “DG” row of the table of FIG. 6A, as shown in FIG. The gradation of the pixel approaches white at the 12th and 12th frames, and dark gray at the 12th frame. In addition, since “0” is stored for the column with the frame number 13 and later in the row “DG” of the table of FIG. 6A, the gradation of the pixel does not change after the 13th frame. It will be.

  Next, the LUT 503 refers to the row “B” in the table of FIG. 6A for pixels whose gradation before rewriting is black and whose gradation after rewriting is black. In this row, since “0” is stored in all the columns, from the first frame to the 31st frame, as shown in FIG. It will not change.

(Operation example when the gradation of the pixel before rewriting is dark gray)
Next, an operation example when the gradation before rewriting of the image is dark gray will be described. When the gradation before rewriting is dark gray, the LUT 503 refers to the table of FIG. 6B and outputs data indicating the voltage applied to the pixel electrode 101d.

  FIG. 9 is a diagram showing the transition of the gradation of a pixel that was dark gray before rewriting when the image is rewritten. FIG. 9A shows the case of dark gray → white, and FIG. In the case of dark gray → light gray, FIG. 9C shows the transition in the case of dark gray → dark gray, and FIG. 9D shows the transition in the case of dark gray → black.

  First, the LUT 503 refers to the row “W” in the table of FIG. 6B for pixels whose gradation before rewriting is dark gray and whose gradation after rewriting is white. In this row, “0” is stored in the column of the frame number 1 and the column of 2, and therefore, in the first frame and the second frame, as shown in FIG. The gradation does not change. Further, in the “W” row of the table of FIG. 6B, since “−” is stored from the column of the frame number 3 to the column of 12, as shown in FIG. The gradation of the pixel approaches white from the third frame, and becomes white at the twelfth frame. In the column of “W” in the table of FIG. 6B, “0” is stored in the column of the frame number 13 and later, so that the gradation of the pixel does not change after the 13th frame. It will be.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 6B for pixels in which the gradation before rewriting is dark gray and the gradation after rewriting is light gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 10, the pixels from the first frame to the tenth frame, as shown in FIG. 9B, Does not change the gradation. In the row of “LG” in the table of FIG. 6B, since “−” is stored in the column of the frame number 11 and the column of 12, as shown in FIG. 9B, The gradation of the pixel approaches white from the 11th frame, and becomes light gray at the 12th frame. Further, in the column of “LG” in the table of FIG. 6B, “0” is stored in the column having the frame number of 13 or later, and therefore, as shown in FIG. 9B, the 13th frame. Thereafter, the gradation of the pixel does not change.

Next, the LUT 503 refers to the row of “DG” in the table of FIG. 6B for a pixel in which the gradation before rewriting is dark gray and the gradation after rewriting is also dark gray.
In this row, since “0” is stored in all the columns, the gradation of the pixel does not change from the first frame to the 31st frame as shown in FIG. 9C. Become.

  Next, the LUT 503 refers to the row “B” in the table of FIG. 6B for pixels whose gradation before rewriting is dark gray and whose gradation after rewriting is black. In this row, since “0” is stored in the column with the frame number 1 and the column 2, as shown in FIG. 9D, in the first frame and the second frame, The gradation does not change. In the row of “B” in the table of FIG. 6B, “−” is stored from the column of the frame number 3 to the column of 12, so that as shown in FIG. The gradation of the pixel approaches white from the third frame, and becomes white at the twelfth frame. Also, “+” is stored in the column “B” in the table of FIG. 6B from the column of the frame number 14 to the column 25. When the gradation control unit 502 acquires “+” as data indicating the voltage applied to the pixel electrode 101d, the gradation control unit 502 transmits a signal instructing the voltage applied to the pixel electrode 101d of the pixel to +15 V to the data line driving circuit 140. Output. When the data line driving circuit 140 outputs a data signal to the data line 114 based on this signal in the period when the scanning line 112 related to the pixel is selected, a voltage of +15 V is applied to the pixel electrode 101d of the pixel. As shown in FIG. 9D, the gradation of the pixel approaches black from the 13th frame and becomes black at the 25th frame. In the row “B” in the table of FIG. 6B, since “0” is stored after the column of the frame number 26, 26 frames as shown in FIG. 9D. After the first eye, the gradation of the pixel does not change.

(Operation example when the gradation of the pixel before rewriting is light gray)
Next, an operation example when the gradation before rewriting of the image is light gray will be described. When the gradation before rewriting is light gray, the LUT 503 refers to the table in FIG. 7A and outputs data indicating the voltage applied to the pixel electrode 101d.

  FIG. 10 is a diagram showing the transition of the gradation of a pixel that was light gray before rewriting when the image is rewritten. FIG. 10A shows the case of light gray → white, and FIG. FIG. 10C shows the transition in the case of light gray → light gray, FIG. 10C shows the transition in the case of light gray → dark gray, and FIG. 10D shows the transition in the case of light gray → black.

  First, the LUT 503 refers to the row “W” in the table of FIG. 7A for pixels in which the gradation before rewriting is light gray and the gradation after rewriting is white. In this row, since “0” is stored from the column of the frame number 1 to the column of 4, in the first to fourth frames, as shown in FIG. The gradation does not change. In the row “W” of the table of FIG. 7A, “−” is stored from the column of the frame number 5 to the column of 12, so as shown in FIG. The gradation of the pixel approaches white from the 5th frame, and becomes white at the 12th frame. Also, in the column “W” in the table of FIG. 7A, “0” is stored in the column of the frame number 13 and later, so that the 13th frame is displayed as shown in FIG. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 7A for pixels in which the gradation before rewriting is light gray and the gradation after rewriting is also light gray. In this row, since “0” is stored in all the columns, the gradation of the pixel does not change from the first frame to the 31st frame as shown in FIG. 10B. Become.

  Next, the LUT 503 refers to the row of “DG” in the table of FIG. 7A for pixels whose gradation before rewriting is light gray and whose gradation after rewriting is dark gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 4, the pixels from the first frame to the fourth frame are displayed as shown in FIG. 10C. Does not change the gradation. In the row of “DG” in the table of FIG. 7A, “−” is stored from the column of the frame number 5 to the column of 12, so that as shown in FIG. The gradation of the pixel approaches white from the 5th frame, and becomes white at the 12th frame. In addition, since “+” is stored from the column of the frame number 14 to the column of 25 in the “DG” row of the table of FIG. 7A, as shown in FIG. The gradation of the pixel approaches black from the 14th frame, and becomes black at the 25th frame. Further, since “−” is stored in the column of the frame number 27 and the column of 28 in the “DG” row of the table of FIG. 7A, as shown in FIG. The gradation of the pixel approaches white from the 27th frame and becomes dark gray at the 28th frame. In the column of “DG” in the table of FIG. 7A, “0” is stored in the column of the frame number 29 and later, and therefore, as shown in FIG. 10C, the 29th frame. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row “B” in the table of FIG. 7A for pixels whose gradation before rewriting is light gray and whose gradation after rewriting is black. In this row, since “0” is stored from the column of the frame number 1 to the column of 4, the pixel from the first frame to the fourth frame, as shown in FIG. Does not change the gradation. Further, in the row “B” in the table of FIG. 7A, since “−” is stored from the column of the frame number 5 to the column of 12, as shown in FIG. The gradation of the pixel approaches white from the 5th frame, and becomes white at the 12th frame. Further, since “+” is stored in the column “B” in the table of FIG. 7A from the column of the frame number 14 to the column 25, the gradation of the pixel is black from the 14th frame. It becomes black at the 25th frame. In the row “B” in the table of FIG. 7A, since “0” is stored after the column of the frame number 26, as shown in FIG. After the first eye, the gradation of the pixel does not change.

(Operation example when the gradation of the pixel before rewriting is white)
Next, an operation example when the gradation before rewriting of the image is white will be described. When the gradation before rewriting is white, the LUT 503 refers to the table of FIG. 7B and outputs data indicating the voltage applied to the pixel electrode 101d.

  FIG. 11 is a diagram showing the transition of the gradation of pixels that were white before rewriting when the image was rewritten. FIG. 11A shows the case of white → white, and FIG. In the case of white → light gray, FIG. 11C shows a transition in the case of white → dark gray, and FIG. 11D shows the transition in the case of white → black.

  First, the LUT 503 refers to the “W” row of the table in FIG. 7B for pixels whose gradation before rewriting is white and gradation after rewriting is also white. In this row, since “0” is stored in all the columns, the gradation of the pixel does not change from the first frame to the 31st frame as shown in FIG. Become.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 7B for pixels whose gradation before rewriting is white and whose gradation after rewriting is light gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 13, the pixels from the first frame to the thirteenth frame are displayed as shown in FIG. 11B. Does not change the gradation. In the row of “LG” in the table of FIG. 7B, since “+” is stored from the column of the frame number 14 to the column of 25, as shown in FIG. The gradation of the pixel approaches black from the 14th frame, and becomes black at the 25th frame. Further, since “−” is stored in the column “LG” in the table of FIG. 7B from the column of the frame number 27 to the column of 30, as shown in FIG. 11B, The gradation of the pixel approaches white from the 27th frame and becomes light gray at the 30th frame. In addition, since “0” is stored in the column of the frame number 31 in the “LG” row of the table of FIG. 7B, as shown in FIG. 11B, in the 31st frame, The gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “DG” in the table of FIG. 7B for pixels whose gradation before rewriting is white and whose gradation after rewriting is dark gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 13, the pixel from the first frame to the thirteenth frame is displayed as shown in FIG. 11C. Does not change the gradation. In addition, since “+” is stored from the column of the frame number 14 to the column of 25 in the “DG” row of the table of FIG. 7B, as shown in FIG. The gradation of the pixel approaches black from the 14th frame, and becomes black at the 25th frame. Further, since “−” is stored in the column of the frame number 27 and the column of 28 in the “DG” row of the table of FIG. 7B, as shown in FIG. The pixel gradation approaches white from the 27th frame, and becomes dark gray at the 28th frame. Since “0” is stored in the column “DG” in the table of FIG. 7B and the column with the frame number 28, the 28th frame is stored as shown in FIG. 11C. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row “B” in the table of FIG. 7B for the pixels whose gradation before rewriting is white and whose gradation after rewriting is black. In this row, since “0” is stored from the column of the frame number 1 to the column of 13, the pixel from the first frame to the thirteenth frame is shown in FIG. Does not change the gradation. In addition, since “+” is stored from the column of the frame number 14 to the column of 25 in the row “B” in the table of FIG. 7B, as shown in FIG. The gradation of the pixel approaches black from the 14th frame, and becomes black at the 25th frame. In the table “B” in the table of FIG. 7B, “0” is stored after the column of the frame number 26, so that the 26th frame is stored as shown in FIG. 11D. Thereafter, the gradation of the pixel does not change.

As described above, in the present embodiment, the pixel that changes the gradation from the low gradation side (black side: first reference gradation side) to the high gradation side (white side: second reference gradation side). Since the gradation changes without going through white, the change in the gradation of the pixel becomes inconspicuous during the rewriting of the image as compared with the configuration through white.
Further, in this embodiment, when rewriting an image, the voltage Vcom is applied to the pixel electrode 101d for all pixels at the last frame of each phase, that is, the 13th frame, the 26th frame, and the 31st frame. The As a result, since the electrophoretic particles are stopped when each phase is started, the gradation is controlled from the state in which the electrophoretic particles easily move in all the pixels 110, and the same gradation is displayed. Differences in gradation are less likely to occur between the pixels 110.
In this embodiment, when light gray and dark gray are displayed, neither light gray nor dark gray is applied from the high gradation side, and a voltage of −15 V is applied to the pixel electrode 101d from the low gradation side. However, since the gradation is controlled by changing the number of times of voltage application, variations in the gradation difference between light gray and dark gray are less likely to occur.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment of the present invention differs from the first embodiment in the configuration of the LUT 503 as compared to the first embodiment. Hereinafter, description of the same configuration as that of the first embodiment will be omitted, and differences will be described.

  The first phase of the present embodiment is a phase in which the gradation is changed for a pixel whose gradation before and after rewriting is different and whose gradation before rewriting is other than black. Also in this embodiment, when the number of the first frame when rewriting an image is 1, the first to 13th frames are in the first phase.

  The second phase of the present embodiment is a phase in which after the first phase, the gradation is changed to white for pixels whose gradation after rewriting is higher than the gradation before rewriting. Also in the present embodiment, when the number of the first frame when rewriting an image is 1, the 14th to 26th frames are in the second phase.

  The third phase of the present embodiment is a phase in which after the second phase, the gradation after the rewriting is higher than the gradation before the rewriting, and the gradation is changed for pixels that become light gray or dark gray after the rewriting. Also in this embodiment, the number of frames in the third phase is 5 frames. When the number of the first frame when rewriting an image is 1, the 27th to 31st frames are in the third phase.

  12 and 13 are diagrams showing tables stored in the LUT 503 according to the present embodiment. As shown in FIGS. 12 and 13, in this embodiment, the polarity of the voltage applied to the pixel electrode 101d is different from that in the first embodiment when the gradation of the pixel is changed in each phase. Specifically, when changing the gradation of the pixel in the first phase, a positive voltage is applied to the pixel electrode 101d, and when changing the gradation of the pixel in the second phase, the negative voltage is applied to the pixel electrode. Apply to 101d. Further, when changing the gradation of the pixel in the third phase, a positive voltage is applied to the pixel electrode 101d.

(Operation example of the second embodiment)
Next, an operation example when rewriting the gradation of a pixel in the first embodiment will be described. In the following description, when the gradation of the pixel before rewriting is black, the gradation of the pixel before rewriting is dark gray, the gradation of the pixel before rewriting is light gray, and the pixel before rewriting An example of the operation when the gradation of white is white will be described.

  FIG. 14 is a diagram showing the transition of the gradation of pixels that were white before rewriting when the image was rewritten. FIG. 14A shows the case of white → white, and FIG. In the case of white → light gray, FIG. 14C shows the transition in the case of white → dark gray, and FIG. 14D shows the transition in the case of white → black. In FIG. 14 and FIGS. 15 to 17 described later, the horizontal axis is the frame number, and the vertical axis is the lightness (gradation) of the pixel. In FIG. 14 and FIGS. 15 to 17 to be described later, “(1)” in the figure indicates the first phase, “(2)” indicates the second phase, and “(3)” indicates the third phase. Show. In the present embodiment, the gray level when the frame number is 0 in FIG. 14D is white (first reference gray level in the present embodiment), and the gray level when the frame number is 2 is light gray. The gradation when the frame number is 4 is dark gray, and the gradation when the frame number is 12 is black (second reference gradation in the present embodiment).

  First, the LUT 503 refers to the row “W” in the table of FIG. 13B for pixels whose gradation before rewriting is white and gradation after rewriting is white. In this row, since “0” is stored in all the columns, the gradation of the pixel does not change from the first frame to the 31st frame as shown in FIG. Become.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 13B for pixels whose gradation before rewriting is white and whose gradation after rewriting is light gray. In this row, since “0” is stored in the columns from the column number 1 to the column 10, the first frame to the tenth frame are shown in FIG. The gradation does not change. In the row of “LG” in the table of FIG. 13B, since “+” is stored in the column of the frame number 11 and the column of 12, the gradation of the pixel is black from the 11th frame. It becomes light gray at the 12th frame. In the column of “LG” in the table of FIG. 13B, “0” is stored in the column after the frame number 13, and therefore, as shown in FIG. 14B, the 13th frame. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “DG” in the table of FIG. 13B for pixels whose gradation before rewriting is white and whose gradation after rewriting is dark gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 8, the pixels from the first frame to the eighth frame are displayed as shown in FIG. 14C. Does not change the gradation. In the row of “DG” in the table of FIG. 13B, “+” is stored from the column of the frame number 9 to the column of 12, so that as shown in FIG. The gradation of the pixel approaches black from the 9th frame, and becomes dark gray at the 12th frame. In the column of “DG” in the table of FIG. 13B, “0” is stored in the column of the frame number 13 and later, so that the 13th frame is displayed as shown in FIG. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row “B” in the table of FIG. 13B for the pixels in which the gradation before rewriting is white and the gradation after rewriting is black. In this row, since “+” is stored from the column of the frame number 1 to the column of 12, the gray level of the pixel approaches black from the first frame as shown in FIG. , It turns black at the 12th frame. In addition, since “0” is stored in the column of the frame number 13 and later in the row “B” in the table of FIG. 13B, as shown in FIG. This means that the gradation of the pixel does not change.

(Operation example when the gradation of the pixel before rewriting is light gray)
Next, an operation example when the gradation before rewriting of the image is light gray will be described. When the gradation before rewriting is light gray, the LUT 503 refers to the table in FIG. 13A and outputs data indicating the voltage applied to the pixel electrode 101d.

  FIG. 15 is a diagram showing the transition of the gradation of a pixel that was light gray before rewriting when the image is rewritten. FIG. 15A shows the case of light gray → white, FIG. FIG. 15C shows the transition in the case of light gray → light gray, FIG. 15C shows the transition in the case of light gray → dark gray, and FIG. 15D shows the transition in the case of light gray → black.

  First, the LUT 503 refers to the row “W” in the table of FIG. 13A for pixels in which the gradation before rewriting is light gray and the gradation after rewriting is white. In this row, since “0” is stored in the column with the frame number 1 and the column with the frame number 2, in the first frame and the second frame, as shown in FIG. Key does not change. In the row “W” in the table of FIG. 13A, “+” is stored from the column of the frame number 3 to the column of 12, so that as shown in FIG. The gradation of the pixel approaches black from the third frame, and becomes black at the twelfth frame. In addition, since “−” is stored from the column of the frame number 14 to the column of 25 in the “W” row of the table of FIG. 13A, as shown in FIG. The gradation of the pixel approaches white from the 14th frame, and becomes white at the 25th frame. Also, in the column “W” in the table of FIG. 13A, “0” is stored in the column of the frame number 26 and later, so that the 26th frame is displayed as shown in FIG. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 13A for pixels in which the gradation before rewriting is light gray and the gradation after rewriting is also light gray. In this row, all “0” are stored. For this reason, from the first frame to the 31st frame, as shown in FIG. 15B, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “DG” in the table of FIG. 13A for pixels whose gradation before rewriting is light gray and whose gradation after rewriting is dark gray. In this row, since “0” is stored in the columns from the column number 1 to the column 10, the first frame to the tenth frame are shown in FIG. The gradation does not change. In the row of “DG” in the table of FIG. 13A, since “+” is stored in the column of the frame number 11 and the column of 12, as shown in FIG. The gradation of the pixel approaches black from the 11th frame, and becomes dark gray at the 12th frame. In the column of “DG” in the table of FIG. 13A, “0” is stored in the column of the frame number 13 and later, so that the 13th frame is displayed as shown in FIG. Thereafter, the gradation of the pixel does not change.

Next, the LUT 503 refers to the row of “B” in the table of FIG. 13A for pixels in which the gradation before rewriting is light gray and the gradation after rewriting is black. In this row, since “0” is stored in the column with the frame number 1 and the column with the frame number 2, in the first frame and the second frame, as shown in FIG. Key does not change.
Further, in the row “B” in the table of FIG. 13A, “+” is stored from the column of the frame number 3 to the column of 12, so as shown in FIG. The gradation of the pixel approaches black from the third frame, and becomes black at the twelfth frame. In the column “B” in the table of FIG. 13A, “0” is stored in the column of the frame number 13 and later. For this reason, as shown in FIG. 15D, the gradation of the pixel does not change after the 13th frame.

(Operation example when the gradation of the pixel before rewriting is dark gray)
Next, an operation example when the gradation before rewriting of the image is dark gray will be described. When the gradation before rewriting is dark gray, the LUT 503 refers to the table of FIG. 12B and outputs data indicating the voltage applied to the pixel electrode 101d.

  FIG. 16 is a diagram showing the transition of the gradation of pixels that were dark gray before rewriting when the image is rewritten. FIG. 16A shows the case of dark gray → white, and FIG. In the case of dark gray → light gray, FIG. 16C shows the transition in the case of dark gray → dark gray, and FIG. 16D shows the transition in the case of dark gray → black.

  First, the LUT 503 refers to the row “W” in the table of FIG. 12B for pixels in which the gradation before rewriting is dark gray and the gradation after rewriting is white. In this row, since “0” is stored from the column of the frame number 1 to the column of 4, the pixels from the first frame to the fourth frame are displayed as shown in FIG. 16A. Does not change the gradation. Also, in the row “W” of the table of FIG. 12B, “+” is stored from the column of the frame number 5 to the column of 12, so that as shown in FIG. The gradation of the pixel approaches black from the 5th frame and becomes black at the 12th frame. In addition, since “−” is stored from the column of the frame number 14 to the column of 25 in the “W” row of the table of FIG. 12B, as shown in FIG. The gradation of the pixel approaches white from the 14th frame, and becomes white at the 25th frame. Also, in the column “W” in the table of FIG. 12B, “0” is stored in the column with the frame number 26 and later, and therefore, as shown in FIG. 16A, the 26th frame. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 12B for pixels whose gradation before rewriting is dark gray and whose gradation after rewriting is light gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 4, the pixels from the first frame to the fourth frame are displayed as shown in FIG. Does not change the gradation. Further, in the row “LG” in the table of FIG. 12B, “+” is stored from the column of the frame number 5 to the column of 12, so as shown in FIG. 16B, The gradation of the pixel approaches black from the 5th frame and becomes black at the 12th frame. In addition, since “−” is stored in the column of “LG” in the table of FIG. 12B from the column of the frame number 14 to the column of 25, as shown in FIG. The gradation of the pixel approaches white from the 14th frame, and becomes white at the 25th frame. Also, since “+” is stored in the column of the frame number 27 and the column of 28 in the “LG” row of the table of FIG. 12B, as shown in FIG. The gradation of the pixel approaches black from the 27th frame and becomes light gray at the 28th frame. Also, in the column “W” in the table of FIG. 12B, “0” is stored in the column of the frame number 29 and later, so that the 29th frame as shown in FIG. 16B. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “DG” in the table of FIG. 12B for pixels in which the gradation before rewriting is dark gray and the gradation after rewriting is also dark gray. Since all “0” are stored in this row, the gradation of the pixel does not change from the first frame to the 31st frame as shown in FIG.

  Next, the LUT 503 refers to the row “B” in the table of FIG. 12B for pixels whose gradation before rewriting is dark gray and whose gradation after rewriting is black. In this row, since “0” is stored from the column of the frame number 1 to the column of 4, the pixels from the first frame to the fourth frame are displayed as shown in FIG. Does not change the gradation. Further, in the row “B” in the table of FIG. 12B, “+” is stored from the column of the frame number 5 to the column of 12, so as shown in FIG. The gradation of the pixel approaches black from the 5th frame and becomes black at the 12th frame. Also, in the column “B” in the table of FIG. 12B, “0” is stored in the column of the frame number 13 and later, so that the 13th frame is displayed as shown in FIG. Thereafter, the gradation of the pixel does not change.

(Operation example when the gradation of the pixel before rewriting is black)
Next, an operation example when the gradation before rewriting of the image is black will be described. When the gradation before rewriting is white, the LUT 503 refers to the table of FIG.

  FIG. 17 is a diagram showing the transition of the gradation of pixels that were black before rewriting when the image was rewritten. FIG. 17A shows the case of black → white, and FIG. In the case of black → light gray, FIG. 17C shows a transition in the case of black → dark gray, and FIG. 17D shows the transition in the case of black → black.

  First, the LUT 503 refers to the row “W” in the table of FIG. 12A for pixels in which the gradation before rewriting is black and the gradation after rewriting is white. In this row, since “0” is stored from the column of the frame number 1 to the column of 13, the pixel from the first frame to the thirteenth frame is displayed as shown in FIG. Does not change the gradation. In addition, since “−” is stored from the column of the frame number 14 to the column of 25 in the row “B” in the table of FIG. 12A, as shown in FIG. The gradation of the pixel approaches white from the 14th frame, and becomes white at the 25th frame. In the table “B” in the table of FIG. 12A, “0” is stored after the column of the frame number 26, so that the 26th frame is stored as shown in FIG. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “LG” in the table of FIG. 12A for pixels whose gradation before rewriting is white and whose gradation after rewriting is light gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 13, the pixel from the first frame to the thirteenth frame is displayed as shown in FIG. Does not change the gradation. In addition, since “−” is stored in the row of “LG” in the table of FIG. 12A from the column of frame number 14 to the column of 25, as shown in FIG. 17B. The gradation of the pixel approaches white from the 14th frame, and becomes white at the 25th frame. Also, since “+” is stored in the column of the frame number 27 and the column of 28 in the “LG” row of the table of FIG. 12A, as shown in FIG. The gradation of the pixel approaches black from the 27th frame and becomes light gray at the 28th frame. Note that “0” is stored in the column “LG” in the table of FIG. 12A and the column with the frame number 28 and thereafter, and therefore, as shown in FIG. 17B, the 28th frame. Thereafter, the gradation of the pixel does not change.

  Next, the LUT 503 refers to the row of “DG” in the table of FIG. 12A for pixels whose gradation before rewriting is black and whose gradation after rewriting is dark gray. In this row, since “0” is stored from the column of the frame number 1 to the column of 13, the pixel from the first frame to the thirteenth frame is displayed as shown in FIG. Does not change the gradation. In addition, since “−” is stored from the column of the frame number 14 to the column of 25 in the “DG” row of the table of FIG. 12A, as shown in FIG. The gradation of the pixel approaches white from the 14th frame, and becomes white at the 25th frame. In addition, since “+” is stored in the column of the frame number 27 to the column 30 in the “DG” row of the table of FIG. 12A, as shown in FIG. The gradation of the pixel approaches black from the 27th frame, and becomes dark gray at the 30th frame. In the column of “DG” in the table of FIG. 12A, “0” is stored in the column of the frame number 31. Therefore, as shown in FIG. The gradation of the pixel does not change.

  Next, the LUT 503 refers to the row “B” in the table of FIG. 12A for pixels whose gradation before rewriting is black and whose gradation after rewriting is black. Since all “0” are stored in this row, the gradation of the pixel does not change from the first frame to the 31st frame as shown in FIG.

As described above, in the present embodiment, the pixel that changes the gradation from the high gradation side (white side: first reference gradation side) to the low gradation side (black side: second reference gradation side). Since the gradation changes without going through black, the change in the gradation of the pixel becomes inconspicuous during the rewriting of the image as compared with the configuration through black.
Also in this embodiment, when rewriting an image, the voltage Vcom is applied to the pixel electrode 101d for all pixels at the last frame of each phase, that is, the 13th, 26th, and 31st frames. The As a result, since the electrophoretic particles are stopped when each phase is started, the gradation is controlled from the state in which the electrophoretic particles easily move in all the pixels 110, and the same gradation is displayed. Differences in gradation are less likely to occur between the pixels 110.
In this embodiment, when displaying light gray and dark gray, light gray or dark gray is not applied from the low gradation side, and a voltage of +15 V is applied to the pixel electrode 101d from the high gradation side. Since gradation is controlled by changing the number of times of voltage application, variations in gradation difference between light gray and dark gray are less likely to occur.

[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, and the electro-optical device 1 and the control unit 2 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 first phase to the third phase are executed on all the pixels 110 in the display region 100 to rewrite the displayed image. However, the present invention is not limited to this configuration. For example, when rewriting an image, an area where a gradation change occurs before and after rewriting is specified. For the specified area, the above three phases are executed, and for pixels 110 in other areas, The voltage Vcom may be applied to the pixel electrode 101d.

In the present invention, the number of frames in each phase is not limited to the number described above, and may be other numbers. In the embodiment described above, when the gradation is changed from white to black, the voltage of +15 V is applied 12 times to the pixel electrode 101d. However, the voltage may be 11 times or less or 13 times or more. In the above-described embodiment, the voltage of −15 V is applied 12 times to the pixel electrode 101d when the gradation is changed from black to white. However, it may be 11 times or less or 13 times or more. Further, the number of application of the voltage of −15 V or +15 V applied when displaying the halftone is not limited to the number of the above-described embodiments, and may be another number of application.
In the above-described embodiment, the temperature of the display region 100 is measured by the temperature sensor, and the number of frames in each phase and the number of applied voltages of + 15V and −15V are changed according to the measured temperature. Good.

  In the above-described embodiments, the active matrix type electro-optical device has been described as an example, but the present invention is not limited to this. The electro-optical device may have a segment type configuration having a segment electrode as the first electrode. In this case, the moving distance of the electrophoretic particles, that is, the magnitude of the gradation change is determined according to the time during which the voltage is applied to the segment electrode. For this reason, in the description of the above-described embodiment, if the number of frames in which the voltage is applied to the pixel electrode 101d is read as the time during which the voltage is applied to the segment electrode, an embodiment of the segment type electro-optical device can be obtained. In the segment-type electro-optical device, the gradation control unit applies a voltage for changing the gradation of the pixel to the segment electrode for an application time corresponding to the gradation difference to be changed, and the pixel having the larger gradation difference, Increase the voltage application time.

  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 may be any device as long as the writing for changing the display state of the pixel is performed by a writing operation in which a voltage is applied a plurality of times. It may be an electro-optical device using.

  In the embodiment described above, the electro-optical device 1 is configured to display four gradations of black, dark gray, light gray, and white, but the gradation to be displayed is not limited to four gradations. . For example, a configuration in which one of dark gray and light gray is not displayed, that is, a configuration in which three gradations are displayed may be employed. Further, gradations other than dark gray and light gray may be displayed as halftones, and gradations of 5 gradations or more may be displayed.

  In the embodiment described above, the voltage Vcom is applied to the pixel electrode 101d in the last frame of each phase, but the present invention is not limited to this configuration. For example, the voltage Vcom may be applied to the pixel electrode 101d in the last frame of at least one of the three phases.

In the electronic book reader 2000 described above, it may be set by operating a button to determine which operation of the first embodiment or the operation of the second embodiment is performed.
For example, when displaying a document, when the background color is white and the character is black or halftone, the operation of the first embodiment is set so that the background color is black and the character is white or intermediate. In the case of a key, it may be set to perform the operation of the second embodiment.

  In the embodiment described above, the amount of change in gradation is different between a case where a voltage of −15 V is applied to the pixel electrode 101 d of the black pixel and a case where a voltage of −15 V is applied to the pixel electrode 101 d of the white pixel. May be different. For example, the amount of change in gradation from black when a voltage of −15 V is applied once to the pixel electrode 101 d of the black pixel is the white balance when the voltage of +15 V is applied once to the pixel electrode 101 d of the white pixel. If it is smaller than the amount of change in gradation from, the operation of the first embodiment may be performed. Further, for example, when a + 15V voltage is applied to the pixel electrode 101d of the white pixel once, the change in gradation from white is applied to the pixel electrode 101d of the black pixel once at a voltage of -15V. If it is smaller than the amount of change in gradation from black, the operation of the second embodiment may be performed.

DESCRIPTION OF SYMBOLS 1 ... Electro-optical device, 2 ... Control part, 5 ... Controller, 10 ... Display part, 100 ... Display area, 101 ... 1st board | substrate, 101a ... Substrate, 101b ... Adhesion layer, 101c ... Circuit layer, 101d ... Pixel electrode, DESCRIPTION OF SYMBOLS 102 ... Electrophoresis layer, 102a ... Microcapsule, 102b ... Binder, 103 ... 2nd board | substrate, 103a ... Film, 103b ... Common electrode layer, 110 ... Pixel, 110a ... TFT, 110b ... Display element, 110c ... Auxiliary capacity, 112 DESCRIPTION OF SYMBOLS ... Scanning line, 114 ... Data line, 130 ... Scanning line drive circuit, 140 ... Data line drive circuit, 501 ... RAM, 502 ... Gradation control part, 503 ... LUT, 1000 ... Display apparatus, 2000 ... Electronic book reader, 2001 …flame

Claims (10)

A first electrode provided in a plurality of pixels, a second electrode disposed opposite to the first electrode, and an electro-optic having memory property disposed between the first electrode and the second electrode An electro-optical device comprising a material,
A gradation control unit for rewriting an image displayed by the pixels;
When the gradation control unit rewrites the image,
The pixel of the second reference gradation side than the gradation of the previous gradation rewriting after rewriting the voltage for changing the gray level of the pixel to the second reference gradation side, after rewriting before rewriting tone Applied to the first electrode with the number of times of application corresponding to the gradation difference from
For the pixels in the first reference gradation side than the gradation of the previous gradation rewriting after rewriting, changing the gray level of the pixel after changing to the second reference tone to said first reference gradation after a voltage for changing the gray level of the pixel to the second reference gradation side, at the applied number of times corresponding to the gradation after rewriting, it is applied to the first electrode
Electro-optic device . 2. The electricity according to claim 1, wherein the gradation control unit sets the voltage of the first electrode to the voltage of the second electrode for a pixel whose gradation does not change before and after rewriting. Optical device . The first voltage for changing the gradation of the pixel to the first reference gradation side and the second voltage for changing the gradation of the pixel to the second reference gradation side are predetermined constant voltages. The electro-optical device according to claim 1, wherein the first voltage and the second voltage have different polarities. The period during which the gradation control unit rewrites an image includes a phase in which the first voltage is applied to the first electrode and a phase in which the second voltage is applied to the first electrode. Item 4. The electro-optical device according to Item 3. The amount of change in gradation when a voltage that changes the gradation toward the second reference gradation is applied to the pixel of the first reference gradation changes the gradation toward the first reference gradation The electro-optical device according to any one of claims 1 to 4, wherein a voltage to be applied is smaller than a change amount of gradation when the voltage to be applied to the pixel of the second reference gradation is applied. The electro-optical device according to claim 1, wherein the second reference gradation is a background color of a displayed image. A first electrode provided in a plurality of pixels, a second electrode disposed opposite to the first electrode, and an electro-optic having memory property disposed between the first electrode and the second electrode An electro-optic device of an electro-optic device comprising:
A gradation control unit for rewriting an image displayed by the pixels;
When the gradation control unit rewrites the image,
For a pixel whose second gray level after rewriting is higher than the gray level before rewriting, the voltage that changes the gray level of the pixel to the second reference gray level is set to the gray level before rewriting and the gray level after rewriting. Applied to the first electrode for an application time corresponding to the gradation difference from
For pixels whose first reference gradation is higher than the gradation before rewriting, the gradation of the pixel is changed to the first reference gradation after the gradation of the pixel is changed to the second reference gradation. Thereafter, a voltage for changing the gradation of the pixel to the second reference gradation side is applied to the first electrode for an application time corresponding to the gradation after rewriting.
Electro-optic device . An electronic apparatus having the electro-optical device according to claim 1 . A first electrode provided in a plurality of pixels, a second electrode disposed opposite to the first electrode, and an electro-optic having memory property disposed between the first electrode and the second electrode A control device for an electro-optical device comprising a material,
A gradation control unit for rewriting an image displayed by the pixels;
When the gradation control unit rewrites the image,
The pixel of the second reference gradation side than the gradation of the previous gradation rewriting after rewriting the voltage for changing the gray level of the pixel to the second reference gradation side, after rewriting before rewriting tone Applied to the first electrode with the number of times of application corresponding to the gradation difference from
For the pixels in the first reference gradation side than the gradation of the previous gradation rewriting after rewriting, changing the gray level of the pixel after changing to the second reference tone to said first reference gradation after a voltage for changing the gray level of the pixel to the second reference gradation side, at the applied number of times corresponding to the gradation after rewriting, it is applied to the first electrode
Control device . A first electrode provided in a plurality of pixels, a second electrode disposed opposite to the first electrode, and an electro-optic having memory property disposed between the first electrode and the second electrode A control method of an electro-optical device comprising:
When rewriting an image displayed by the pixels,
The pixel of the second reference gradation side than the gradation of the previous gradation rewriting after rewriting the voltage for changing the gray level of the pixel to the second reference gradation side, after rewriting before rewriting tone Applied to the first electrode with the number of times of application corresponding to the gradation difference from
For the pixels in the first reference gradation side than the gradation of the previous gradation rewriting after rewriting, changing the gray level of the pixel after changing to the second reference tone to said first reference gradation after a voltage for changing the gray level of the pixel to the second reference gradation side, at the applied number of times corresponding to the gradation after the rewriting, a control method to be applied to the first electrode.

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