JP2014095922A - Method for driving electrophoretic display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-optical device enabling display switching at high speed.SOLUTION: An electro-optical device of the present invention comprises: a display section in which a plurality of pixels are formed; a pulse counter for acquiring an initial value of a control value c (c is a natural number) used for when causing the display section to display an image; a calculation section for decreasing the control value c each time when the image of the display section is re-written; and a control section for selecting one driving method out of a plurality of driving methods according to the control value c, and for re-writing the image of the display section by using the selected driving method.

Description

  The present invention relates to an electro-optical device.

  In an electrophoretic display device that is an aspect of an electro-optical device including a memory-type display element, when updating a display image on a display unit, an image before update (previous image) is deleted and, for example, the entire surface is displayed in white After that, the operation of writing the black display portion of the image to be displayed next is executed over a plurality of frames (see, for example, Patent Document 1).

JP 2002-149115 A

  However, in the above driving method, since the operation of writing the same image to the display unit a plurality of times is performed, there is a problem that it takes time to update the display, which is particularly noticeable when the number of pixels in the display unit is large. Therefore, there has been a problem that a plurality of images cannot be displayed continuously while updating the images at high speed. In this specification, displaying a plurality of images continuously is referred to as continuous display.

  SUMMARY An advantage of some aspects of the invention is that it provides an electro-optical device and a driving method thereof capable of high-speed continuous display.

  The electro-optical device of the present invention includes a display unit having a plurality of pixels, a control value acquisition unit that acquires an initial value of a control value c used when displaying an image on the display unit, and an image on the display unit is rewritten. A calculation unit that reduces the control value c each time the control value c is selected, and a control unit that selects one drive method from a plurality of drive methods according to the value of the control value c and rewrites the image on the display unit using the selected drive method The control value c is an integer, and one pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, and the first electrode. And an electro-optic material layer sandwiched between the second electrode and the control unit that performs a first erasing operation, a second erasing operation, and an image display operation. A driving method, a second driving method for executing an erasing operation and an image display operation, and a display on the display unit. And a third drive method for executing a differential image display operation for displaying a differential image between the current image and a new image, and when performing image rewriting a number of times corresponding to the initial value of the control value c, The first driving method is selected when c is a predetermined value L (L is an arbitrary integer) or more and less than a predetermined value M (M is an integer of L + 1 or more), and the control value c is a predetermined value M or more and a predetermined value. The second drive method is selected when the value is less than a value N (N is an integer equal to or greater than M + 1), and the third drive method is selected when the control value c is equal to or greater than a predetermined value N. To do.

  According to this configuration, since the driving method of the display unit is selected according to the value of the control value c that is subtracted every time the image is rewritten, the remaining number of image rewrites is performed when continuous image rewriting is performed. Accordingly, an appropriate driving method can be selected. Therefore, for example, when the remaining number of image rewrites is large, it is possible to select a driving method capable of displaying an image at a higher speed than when the remaining number of image rewrites is small. In other words, when the control value c is large, it is possible to select a driving method capable of displaying an image at a higher speed than when the control value c is small. As a result, an electro-optical device capable of high-speed continuous display can be obtained.

The driving method selected from the plurality of driving methods when the control value c is equal to a predetermined lower limit value may be configured to be slower than the driving method selected when the control value c is another value. Good.
Usually, when the image rewriting speed is increased, the voltage application period to the electro-optical material layer is shortened or the applied voltage is lowered, so that the display quality is deteriorated. Therefore, as in the present configuration, when the control value c is the lower limit value, the subsequent display is fixed by selecting a driving method that is slower than when the control value c is another value. A high-quality display can be obtained in the last image display. As a result, both high-speed continuous display and high-quality display can be achieved.

The control value c is an integer, and one pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, the first electrode, and the second electrode. An electro-optic material layer sandwiched between the first driving method for performing the first erasing operation, the second erasing operation, and the image display operation; A second driving method for executing an operation and an image display operation; and a third driving method for executing a difference image display operation for displaying a difference image between an image displayed on the display unit and a new image. When the image rewriting is performed a number of times corresponding to the initial value of the control value c, the control value c is equal to or greater than a predetermined value L (L is an arbitrary integer) and less than a predetermined value M (M is an integer equal to or greater than L + 1). And the control value c is equal to or greater than a predetermined value M and a predetermined value N (N is M + 1). Select the second driving method when the upper integer) is less than the third driving method may be configured to select when the control value c is a predetermined value or more N.
According to this configuration, when a plurality of pages are continuously displayed, when the control value c corresponding to the remaining number of times of rewriting the screen is large, a relatively high-speed display is performed, and when the control value c is small (the remaining number is When the number is small, a high-quality display can be performed at a relatively low speed, so that both a high-speed continuous display and a high-quality display can be achieved.

The control value c is an integer, and one pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, the first electrode, and the second electrode. And an electro-optic material layer sandwiched between
The controller includes a first driving method for executing a first erasing operation, a second erasing operation, and an image display operation, and a second driving method for executing an erasing operation and an image display operation. When the image rewriting is performed a number of times corresponding to the initial value of the control value c, the control value c is equal to or greater than a predetermined value L (L is an arbitrary integer) and less than a predetermined value M (M is an integer equal to or greater than L + 1). The first driving method may be selected, and the second driving method may be selected when the control value c is a predetermined value M or more.
According to this configuration, when a plurality of pages are continuously displayed, when the control value c corresponding to the remaining number of times of rewriting the screen is large, a relatively high-speed display is performed, and when the control value c is small (the remaining number is When the number is small, a high-quality display can be performed at a relatively low speed, so that both a high-speed continuous display and a high-quality display can be achieved.

In the second driving method, after the erasing operation for shifting the entire display portion to the first gradation, at least some of the plurality of pixels are different from the first gradation. At least a part of the plurality of pixels after the first mode of executing the image display operation for shifting to the second gradation and the erasing operation for shifting the entire display unit to the second gradation. And a second mode for executing the image display operation for shifting pixels to the first gradation.
In such a configuration, the first mode and the second mode differ only in the gradation value of the pixel driven in each operation. However, depending on the type of the electro-optic material layer, the first mode and the second mode are different. The display state and the visibility of the display unit may differ depending on the mode. Therefore, if the configuration includes both the first mode and the second mode, the first mode and the second mode can be switched and used according to the characteristics of the electro-optical material layer and the image data to be displayed. This makes it easy to obtain a high-quality display.

The control value c is an integer, and one pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, the first electrode, and the second electrode. An electro-optic material layer sandwiched between the first erasing operation, the second erasing operation, and the image display operation in accordance with the gradation to be displayed. A first driving method executed while switching the potential of the two electrodes, and a difference image between an image displayed on the display unit and the next image displayed with the second electrode held at a constant potential And a second driving method for executing a differential image display operation for writing the control value, and when the image rewriting is performed a number of times corresponding to the initial value of the control value c, the control value c is equal to or greater than a predetermined value L (L is an arbitrary integer). When the first driving method is less than a predetermined value M (M is an integer equal to or greater than L + 1), -Option, and may be configured to select the second driving method when the control value c is a predetermined value or more M.
According to this configuration, when a plurality of pages are continuously displayed, when the control value c corresponding to the remaining number of times of rewriting the screen is large, a relatively high-speed display is performed, and when the control value c is small (the remaining number is When the number is small, a high-quality display can be performed at a relatively low speed, so that both a high-speed continuous display and a high-quality display can be achieved.

The control value acquisition unit may measure an input signal pulse supplied from an input device connected to the electro-optical device for a predetermined period and set an initial value of the control value c based on the measured number of pulses. Good.
According to this configuration, the initial value of the control value c can be set according to the number of times the button constituting the input device is pressed and the rotation angle of the jog dial.

The first driving method may be configured to be slower than a driving method selected from the plurality of driving methods when the control value c is equal to or greater than a predetermined value M.
According to this configuration, high-quality display can be performed at a relatively low speed when the control value c is small.

The predetermined value L may be 1.
According to this configuration, the driving method applied when writing an image to be fixedly displayed can be a driving method capable of performing high-quality display at a relatively low speed.

1 is an external view of an electronic book reader according to a first embodiment. The figure which shows the internal structure of an electronic book reader. The figure which shows the electrical constitution of an electro-optical panel. The flowchart of the page switching process in an electronic book reader. The figure which shows the operation | movement flow of a pulse counter. The figure which shows the drive waveform in each operation | movement which comprises a drive sequence. Operation | movement explanatory drawing of an electrophoretic element. The figure which shows the drive waveform in each operation | movement which comprises a drive sequence. The figure which shows the drive waveform in each operation | movement which comprises a drive sequence.

(First embodiment)
The electro-optical device of the present invention will be described below with reference to the drawings.
The scope of the present invention is not limited to the following embodiment, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each structure easy to understand, the actual structure may be different from the scale, number, or the like in each structure.

The electrophoretic display device according to the present embodiment is an electronic book reader that can browse an electronic book or the like composed of documents divided into predetermined pages.
FIG. 1 is an external view of an electronic book reader 100 according to this embodiment. FIG. 2 is a block diagram showing an internal configuration of the electronic book reader 100 of the present embodiment.

  As shown in FIG. 1, the electronic book reader 100 includes a housing 101 and an electro-optical panel 112 attached to a rectangular opening 101 a formed on one surface of the housing 101. The housing 101 is provided with a page advance button 105, a page return button 106, an enter button 108, a skip advance button 115, and a skip return button 116.

The page feed button 105 is an operation unit that activates a function of feeding and displaying the next page and subsequent pages of the document (image) currently displayed on the electro-optical panel 112 by one page each time the button is pressed. The page return button 106 is an operation unit that activates a function of displaying the previous page of the document before the previous page by one page each time it is pressed.
The skip feed button 115 is an operation unit that activates a function of displaying, for example, a page 10 pages ahead each time the button is pressed once. The skip back button 116 is an operation unit that activates a function of displaying, for example, the previous 10 pages each time the button is pressed once. The number of page skips of the skip sending button 115 and the skip return button 116 can be arbitrarily set.

  As shown in FIG. 2, the electronic book reader 100 includes a CPU (Central Processing Unit; control unit) 102, a display unit control device 110, a storage device 111, an electro-optical panel 112, an input device 113, a pulse counter 114, A VY power supply 161, a VX power supply 162, and a common power supply 163 are provided.

  Note that a work memory and a program memory (not shown) are connected to the CPU 102 shown in FIG. The work memory is a RAM (Random Access Memory) constituting a work area of the CPU 102, and the program memory is a ROM (Read Only Memory) holding various programs. These work memory and program memory may be included in the storage device 111, or may be provided as a storage device different from the storage device 111. Alternatively, the CPU 102 may include a work memory or a program memory.

The CPU 102 reads various programs and data such as basic control programs and application programs stored in the program memory, develops and executes these various programs and data in a work area provided in a work memory (not shown), and the electronic book Control each part of the leader. In the present embodiment, the CPU 102 also calculates the control value c corresponding to the remaining number of times of rewriting the screen when continuously displaying a plurality of pages. Therefore, the calculating unit reduces the control value c every time the image is rewritten. Also works.
A display unit control device 110 and a pulse counter 114 are connected to the CPU 102. An electro-optical panel 112 and a common power source 163 are connected to the display unit control device 110, and a VY power source 161 and a VX power source 162 are connected to the electro-optical panel 112. On the other hand, an input device 113 is connected to the pulse counter 114.

  The input device 113 includes the page advance button 105, the page return button 106, the determination button 108, the skip advance button 115, and the skip return button 116 shown in FIG. 1, and when any of these buttons is operated (pressed), A signal (pulse) corresponding to the pressed button is output to the pulse counter 114.

  The pulse counter 114 is a control value acquisition unit that acquires an initial value of the control value c. The pulse counter 114 counts input pulses input from the input device 113 for a predetermined period, and outputs the obtained count value to the CPU 102 as a control value c. For example, the pulse counter 114 stores the storage area for storing the number of times the button of the input device 113 is pressed within a predetermined period and the count value held in the storage area for each predetermined period or in response to a request from the CPU 102. And a control circuit for outputting to the control circuit. The count value held in the storage area is cleared every time the control value c is output.

The pulse counter 114 is not limited to the configuration in which the count value is directly output as the control value c as described above (the configuration in which the count value and the page feed number correspond one-to-one), and the input pulse is converted into a predetermined conversion algorithm. It is good also as a structure which converts based on this and outputs this conversion value to CPU102 as the control value c. In this embodiment, since the count value is output as it is as the control value c, c is an integer.
For example, when the input device 113 is a device that outputs a large number of pulses, such as a jog dial, if the number of output pulses is set as the number of page feeds as it is, the number of pages may be excessive. In such a case, it is preferable to set the control value c by converting the count value so that there is one page for a plurality of pulses.

The display controller 110 includes an overall controller 140, an image data write controller 141, a timing signal generator 142, a common power controller 143, a storage device controller 144, and an image data read controller 145. The image signal generation unit 146 and the selection signal generation unit 147 are included.
An image data write control unit 141, a timing signal generation unit 142, and a common power supply control unit 143 are connected to the overall control unit 140. A storage device control unit 144 is connected to the image data write control unit 141. An image data read control unit 145, an image signal generation unit 146, and a selection signal generation unit 147 are connected to the timing signal generation unit 142. A common power supply 163 is connected to the common power supply control unit 143.
The display unit control device 110 is connected to the CPU 102 in the overall control unit 140, is connected to the electro-optical panel 112 in the image signal generation unit 146 and the selection signal generation unit 147, and is connected to the storage device 111 in the storage device control unit 144. Yes.

The storage device 111 includes a previous image holding unit 120 and a next image holding unit 121, both of which are RAMs. The previous image holding unit 120 is a storage area for holding image data (image data corresponding to the currently displayed image) after being displayed on the electro-optical panel 112, and the next image holding unit 121 is stored in the electro-optical panel 112. This is a storage area for holding image data to be displayed next (image data corresponding to an updated image).
Both the previous image holding unit 120 and the next image holding unit 121 are connected to the storage device control unit 144 of the display unit control device 110, and the display unit control device 110 is connected to the storage device 111 via the storage device control unit 144. Read and write image data.

  The electro-optical panel 112 includes a display unit 150 including a memory display element such as an electrophoretic element or a cholesteric liquid crystal element, and a scanning line driving circuit 151 and a data line driving circuit 152 connected to the display unit 150. Yes. A common power source 163 is connected to the display unit 150. A VY power supply 161 and a selection signal generation unit 147 of the display unit control device 110 are connected to the scanning line driving circuit 151. A VX power source 162 and an image signal generation unit 146 of the display unit control device 110 are connected to the data line driving circuit 152.

Here, FIG. 3 is a diagram showing an electrical configuration of the electro-optical panel 112.
As shown in FIG. 3, the display unit 150 of the electro-optical panel 112 has a plurality of scanning lines G (G1, G2,..., Gm) extending in the X-axis direction and a Y-axis direction. A plurality of data lines S (S1, S2,..., Sn) are formed. Pixels 10 are formed corresponding to the intersections between the scanning lines G and the data lines S. The pixels 10 are arranged in a matrix of m pieces along the Y-axis direction and n pieces along the X-axis direction, and a scanning line G and a data line S are connected to each pixel 10. In the display unit 150, a common electrode line COM and a capacitor line C extending from the common power source 163 are formed.

In the pixel 10, a selection transistor 21 as a pixel switching element, a storage capacitor 22, a pixel electrode 24, a common electrode 25, and an electro-optic material layer 26 are formed.
The selection transistor 21 is configured by an N-MOS (Negative-channel Metal Oxide Semiconductor) TFT. The scanning line G is connected to the gate of the selection transistor 21, the data line S is connected to the source, and one electrode of the storage capacitor 22 and the pixel electrode 24 are connected to the drain.
The storage capacitor 22 is composed of a pair of electrodes that are arranged to face each other with a dielectric film interposed therebetween. One electrode of the storage capacitor 22 is connected to the drain of the selection transistor 21, and the other electrode is connected to the capacitor line C. The image signal written through the selection transistor 21 by the storage capacitor 22 can be maintained for a certain period.
The electro-optic material layer 26 is composed of an electrophoretic element, a cholesteric liquid crystal element, an electronic powder element, or the like. For example, examples of the electrophoretic element include a device in which microcapsules in which electrophoretic particles and a dispersion medium are enclosed, and a device in which electrophoretic particles and a dispersion medium are enclosed in a space partitioned by a partition wall and a substrate.

  The scanning line driving circuit 151 is connected to the scanning line G formed in the display unit 150, and is connected to the pixel 10 in the corresponding row via each scanning line G. The scanning line driving circuit 151 generates a selection signal for each of the scanning lines G1, G2,..., Gm based on the timing signal supplied from the timing signal generation unit 142 illustrated in FIG. The selection signals generated by the unit 147 are sequentially supplied in the form of pulses, and each of the scanning lines G is sequentially selected exclusively. The selected state is a state in which the selection transistor 21 connected to the scanning line G is on.

  The data line driving circuit 152 is connected to the data line S formed in the display unit 150, and is connected to the pixel 10 in the corresponding column via each data line S. Based on the timing signal supplied from the timing signal generation unit 142 via the image signal generation unit 146, the data line driving circuit 152 generates an image generated by the image signal generation unit 146 on the data lines S1, S2,. Supply signal.

  In the description of the operation described later, the image signal takes a binary potential of a high level potential VH (for example, 15V) or a low level potential VL (for example, 0V or −15V). In the present embodiment, a high-level image signal (VH) is supplied to the pixel 10 on which black (first gradation) is to be displayed, and the pixel on which white (second gradation) is to be displayed. 10 is supplied with a low-level image signal (VL).

The common electrode 25 is supplied with the common electrode potential Vcom from the common power source 163, and the capacitor line C is supplied with the capacitor line potential Vss from the common power source 163.
However, in the description of the driving method described later, for the sake of simplicity, the common electrode potential Vcom is a low-level potential VL (for example, 0V or −15V) or a high-level potential VH (for example, 15V). Shall be taken. Further, it is assumed that the capacitance line potential Vss is fixed to a reference potential (for example, 0 V).

  In the present embodiment, the active matrix type electro-optical panel 112 including the scanning line driving circuit 151 and the data line driving circuit 152 is shown. However, as the electro-optical panel 112, a passive matrix type or segment driving type electric optical panel 112 is used. It may be an optical panel.

(Document display operation)
Next, a document display operation in the electronic book reader will be described with reference to the drawings.
The electronic book reader 100 according to this embodiment can continuously display a plurality of pages one after another even when the button is continuously pressed a plurality of times on the input device 113. More specifically, when a continuous page feed (page return) instruction is input, a control value c indicating the number of times the image should be rewritten is acquired, and the control value c is subtracted every time the image is rewritten. When the image is rewritten, that is, when the next page is displayed, a different driving sequence (driving method) is set according to the value of the control value c, and an image is displayed using the driving sequence. As a result, an image is displayed at high speed during continuous page feed operations, while a high-quality display is obtained on the last fixed page displayed during page feed.

  FIG. 4 is a flowchart of the page switching process in the electronic book reader 100 of this embodiment. FIG. 5 is a diagram showing an operation flow of the pulse counter. FIG. 6 is a diagram showing drive waveforms in each operation constituting the drive sequence.

  The page switching process of this embodiment is a process executed when the input device 113 (page feed button 105, page return button 106, skip forward button 115, skip back button 116, etc.) shown in FIG. 1 is operated. is there. Alternatively, the page switching process of the present embodiment may be executed only when the input device 113 is continuously pressed a plurality of times.

Of course, the image displayed on the electro-optical panel 112 in the page switching process varies depending on the type of button operated on the input device 113.
For example, when the page feed button 105 of the input device 113 is pressed a plurality of times, pages subsequent to the next page of the document are sequentially displayed by the number (control value c) corresponding to the number of times the button is pressed. . When the page return button 106 of the input device 113 is pressed a plurality of times, the pages before the previous page of the document are sequentially displayed by the number corresponding to the number of times the button is pressed (control value c). .
Further, when the skip sending button 115 of the input device 113 is pressed a plurality of times, the display starts from 10 pages ahead of the document, and skips 10 pages by the number (control value c) corresponding to the number of times the button is pressed. The pages are sent sequentially. When the skip return button 116 of the input device 113 is pressed a plurality of times, the display starts from 10 pages before the document, and skips 10 pages by the number (control value c) corresponding to the number of times the button is pressed. Pages are returned sequentially.
In this embodiment, page feed is performed when the control value c (integer) is positive, but page feed is not performed when the control value c is 0 (zero) or negative. In other words, since the lower limit value of the control value c for rewriting the image is 1, the number of times that the image is rewritten is c in any case.

  Hereinafter, the page switching process according to the present embodiment will be described in detail with reference to FIGS. 4 to 6. In the following description, the electro-optical material layer 26 is an electrophoretic element for easy understanding of the invention. Will be described.

FIG. 7 is an explanatory diagram of the operation of the electrophoretic element. FIG. 7A shows a case where the pixel is displayed in white, and FIG. 7B shows a case where the pixel is displayed in black.
In the case of white display shown in FIG. 7A, the common electrode 25 is held at a relatively high potential and the pixel electrode 24 is held at a relatively low potential. Thereby, the negatively charged white particles 27 are attracted to the common electrode 25, while the positively charged black particles 28 are attracted to the pixel electrode 24. As a result, when this pixel is viewed from the common electrode 25 side which is the display surface side, white (W) is recognized.
In the case of black display shown in FIG. 7B, the common electrode 25 is held at a relatively low potential, and the pixel electrode 24 is held at a relatively high potential. As a result, the positively charged black particles 28 are attracted to the common electrode 25, while the negatively charged white particles 27 are attracted to the pixel electrode 24. As a result, when this pixel is viewed from the common electrode 25 side, black (B) is recognized.

The page switching process of this embodiment includes steps S101 to S108 shown in FIG.
First, in step S101, the CPU 102 determines whether or not the electronic book reader 100 is in a page switchable state. For example, when an operation menu, a selection dialog, or the like is displayed on the electro-optical panel 112 instead of a document, the page switching process is terminated as it is because the page cannot be switched. On the other hand, when the document is displayed on the electro-optical panel 112 of the electronic book reader 100 and the page can be switched, the process proceeds to step S102.

Next, in step S <b> 102, the CPU 102 acquires the control value c output from the pulse counter 114. In a succeeding step S103, it is determined whether or not the control value c is 0 (zero). If the control value c is 0, page feed is not performed, and the page switching process is terminated as it is.
The case where the control value c is 0 means that the calculation result in step S108 described later is c = 0 (that is, the continuous display operation (page feed) of the number of pages instructed by the user by operating the input device 113). Is typical).
In addition to the above, for example, when a button other than a button related to page switching (for example, the determination button 108) is pressed, or the input device 113 is a jog dial and the number of pulses output from the jog dial corresponds to one page feed. The control value c is 0 even when it is less than the number.
On the other hand, when the control value c is an integer of 1 or more, the process proceeds to step S104.

Here, the operation of the pulse counter 114 will be described with reference to FIG.
As shown in FIG. 5, the operation flow of the pulse counter 114 includes steps S201 to S207. In the electronic book reader 100, the timer used for timing by the pulse counter 114 may be in a pause state to reduce power consumption. In such a case, the timer is started when the input device 113 is operated. There is a need to. FIG. 5 shows the operation of the pulse counter 114 including timer activation.

  As shown in step S201 of FIG. 5, the pulse counter 114 monitors the supply of the input pulse from the input device 113. When the input pulse is detected, the pulse counter 114 executes step S202 and subsequent steps and outputs the control value c. To do.

  When the pulse counter 114 detects the input pulse, the pulse counter 114 proceeds to step S202 for determining the state of the timer. If it is determined that the timer is inactive, the process proceeds to step S203 to start the timer, and then proceeds to step S204. If the timer has already been started, the process proceeds from step S202 to step S204.

  In step S204, the input pulses supplied from the input device 113 are counted (the count value held by the pulse counter 114 is incremented by 1). Subsequently, in step S205, it is determined whether or not the elapsed time measured by the timer exceeds the set time. If the elapsed time is equal to or shorter than the set time, the process returns to step S201 to continue monitoring the input pulse. . On the other hand, if the set time has elapsed, the process proceeds to step S206, and the control value c is output to the CPU 102 based on the count value. After outputting the control value c, the count value is cleared in step S207, and the process ends.

Returning to FIG. 4, in step S <b> 104 of the page switching process, the CPU 102 refers to the data table using the acquired control value c, and identifies the drive sequence (drive method) to be selected.
Table 1 below is a table showing an outline of the data table referred to in step S104. Table 2 is a table showing the configuration of the drive sequence shown in Table 1.

In Table 1, N is a natural number of 3 or more, and M is a natural number of 2 or more and less than N. These M and N are constants set appropriately and are not particularly limited.
In the data table shown in Table 1, the value of the control value c is classified into three levels, and the drive sequence SQ11, the drive sequence SQ12, and the drive sequence SQ13 are associated with each level. The CPU 102 refers to the data table using the control value c acquired in step S102, and acquires drive sequences SQ11 to SQ13 corresponding to the level to which the control value c belongs.

For example, when N = 8 and M = 4, the drive sequence SQ13 is selected when the control value c is 8 or more, and the drive sequence SQ12 is selected when the control value c is 4-7. When the control value c is 1 to 3, the drive sequence SQ11 is selected.
When N = 4 and M = 2, the drive sequence SQ13 is selected when the control value c is 4 or more, and the drive sequence SQ12 is selected when the control value c is 2 or 3. The drive sequence SQ11 is selected only when the control value c is selected.

  As shown in Table 2, the drive sequences SQ11 to SQ13 differ in the configuration of operations executed in the electro-optical panel 112. Hereinafter, each drive sequence will be described with reference to Table 2 and FIG.

<Drive sequence SQ11>
The drive sequence SQ11 is a drive sequence selected when the control value c belongs to the first level (1 ≦ c <M). As shown in Table 2, the inversion erase step (first erase operation) and , An all white erasing step (second erasing operation) and an image displaying step (image displaying operation). Further, FIG. 6A shows potentials respectively input to the pixel electrode 24 and the common electrode 25 in one pixel 10 of the display unit 150, ST11 is an inversion erasing step, ST12 is an all white erasing step, ST13 corresponds to each image display step.
As described above, the lower limit value of the control value c for rewriting an image is set to 1, and at least when the control value c is equal to the lower limit value, the drive sequence SQ11 is selected.

The reverse erasing step ST11 is a process in which black is written to pixels displaying white in the image (previous image) displayed on the electro-optical panel 112 immediately before the page switching process, whereby the entire surface of the display unit 150 is displayed. This is an operation of shifting (all pixels) to black display. Thereby, the previous image can be erased. In FIG. 6, such erasure is shown as inverted all black erasure.
FIG. 6A shows the input potential in the pixel 10 that performs the black display operation in the inversion erasing step ST11. As shown in the drawing, the pixel electrode 24 (potential Vs) is inputted with a high level potential VH, and the common electrode 25 (potential Vcom) held at the reference potential GND is set to a high potential, so that the pixel 10 displays black. (See FIG. 7B).
Note that the same potential (reference potential) as the potential Vcom of the common electrode 25 is input to the pixel electrode 24 of the pixel 10 that has been displayed black in the previous image, and the pixel 10 maintains black display.

  The all white erasing step ST12 is an operation of displaying white on the entire surface by writing white to all the pixels of the display unit 150. In the all white erasing step ST12, as shown in FIG. 6A, the low level potential VL is input to the pixel electrodes 24 of all the pixels 10, and the pixel electrode 24 has a lower potential than the common electrode 25 (potential Vcom). (See FIG. 7A).

In the image display step ST13, display based on image data of an image (next image) to be displayed next on the display unit 150 is performed. As shown in Table 2, the image display step ST13 in the drive sequence SQ11 is single color writing. Specifically, by writing black to the pixel that should display black in the next image, the all white erasing step ST12. Only the black display portion of the next image is drawn on the display unit 150 that is displayed white in FIG. In FIG. 6, such a writing operation is indicated as black component writing. The next image can be displayed by this image display step ST13.
FIG. 6A shows the input potential at the pixel 10 displayed in black in the image display step ST13. In the pixel 10, the high level potential VH is input to the pixel electrode 24, and the pixel electrode 24 is held at a high potential with respect to the common electrode 25. On the other hand, in the pixel 10 that maintains white display, the same reference potential as the potential Vcom of the common electrode 25 is input to the pixel electrode 24.

<Drive sequence SQ12>
The drive sequence SQ12 is a drive sequence that is selected when the control value c belongs to the second level (M ≦ c <N). As shown in Table 2, an inversion erasing step (erasing operation) and an image display are performed. Step (image display operation).
FIGS. 6B and 6C show two types of modes (SQ12A, SQ12B) of the drive sequence SQ12, and the pixel electrode 24 and the common electrode 25 in one pixel 10 of the display unit 150 for each mode. The input waveform to is shown. In FIG. 6, ST11a and ST11b correspond to the reverse erasing step, and ST13a and ST13b correspond to the image display step, respectively.

First, in the inversion erasing step ST11a of the drive sequence SQ12A shown in FIG. 6B, for the pixels displaying white in the image (previous image) displayed on the electro-optical panel 112 immediately before the page switching process. By writing black, the entire surface (all pixels) of the display unit 150 is shifted to black display.
FIG. 6B shows the input potential of the pixel 10 displayed in black in the inversion erasing step ST11a. In the pixel 10, the high level potential VH is input to the pixel electrode 24 (potential Vs), and the potential is set higher than the common electrode 25 (potential Vcom) held at the reference potential GND. On the other hand, the same potential (reference potential) as the potential Vcom of the common electrode 25 is input to the pixel electrode 24 of the pixel 10 that has been displayed in black in the previous image.

Next, in the image display step ST13a, display based on the image data of the next image to be displayed on the display unit 150 is performed. Specifically, by writing white to the pixel that should display white in the next image, the white component (white display portion) of the next image is displayed on the display unit 150 that has been displayed in black in the reverse erasing step ST11a. Is written. In FIG. 6, such a writing operation is shown as white component writing.
FIG. 6B shows the input potential in the pixel 10 that is displayed in white in the image display step ST13a. In the pixel 10, the low level potential VL is input to the pixel electrode 24, and is set to a low potential with respect to the common electrode 25 held at the reference potential GND. On the other hand, in the pixel 10 whose display is not changed, the same reference potential as the potential Vcom of the common electrode 25 is input to the pixel electrode 24.

On the other hand, in the drive sequence SQ12B, the black component of the next image is written in the image display step ST13b with respect to the display unit 150 that has been displayed in white in the reverse erasing step ST11b. In the drive sequence SQ12A and the drive sequence SQ12B, the relationship between white and black is opposite to each other.
Therefore, as shown in FIG. 6C, in the reverse erasing step ST11b, the low level potential VL is input to the pixel electrode 24 of the pixel 10 to be driven (displayed in white), and the pixel electrode 24 of the pixel 10 that is not driven. Is supplied with a reference potential GND.
In the image display step ST13b, the high level potential VH is input to the pixel electrode 24 of the pixel 10 to be driven (displayed in black), and the reference potential GND is input to the pixel electrode 24 of the pixel 10 that is not driven.

  The drive sequence SQ12A and the drive sequence SQ12B are common in that an erase operation is performed only once and an image is displayed thereafter, and the display speed and power consumption are also the same. Therefore, the electronic book reader 100 only needs to have at least one of the drive sequences SQ12A and SQ12B.

On the other hand, since the drive sequences SQ12A and SQ12B have the following characteristics, the characteristics of each aspect and the characteristics of the electro-optical panel 112 (ease of occurrence of afterimage, response speed, etc.) are taken into consideration. It is also preferable that the drive sequence can be set for each scene.
In the drive sequence SQ12A, the display unit 150 is displayed in black in the reverse erasing step ST11a, so that an afterimage is hardly generated, but the user can easily see the blinking (flushing) of the screen. On the other hand, in the drive sequence SQ12B, since the black display portion is shifted to white display in the inversion / erasure step ST11b, an afterimage is likely to occur in the pixels that are displayed white in the previous image, but the screen does not flash.
In the present specification, as in the reverse erasing step ST11, the first gradation, for example, white is displayed among the images (previous image) displayed on the electro-optical panel 112 immediately before the page switching process. The operation of shifting the entire surface (all pixels) of the display unit 150 to the second gradation by writing the second gradation, for example, black, to the pixel is expressed as writing an inverted image. Of the image (previous image) displayed on the electro-optical panel 112 immediately before the page switching process, writing is not performed on the pixel displaying the second gradation.

<Drive sequence SQ13>
The drive sequence SQ13 is a drive sequence selected when the control value c belongs to the third level (c ≧ N), and includes only an image display step (image display operation) as shown in Table 2.
In the image display step ST13c in the drive sequence SQ13, the pixel 10 is driven using difference data between the next image displayed on the display unit 150 and the previous image displayed immediately before. That is, when the display image is switched from the previous image to the next image, only the pixels 10 whose gradation changes are driven, and the display state of the pixels 10 whose gradation does not change is maintained as it is. Specifically, among the pixels displaying black in the previous image, white is written to the pixels displaying white in the next image, and among the pixels displaying white in the previous image, black is displayed in the next image. Black is written to the pixels that display. However, among the pixels displaying black in the previous image, the pixels displaying black in the next image, and among the pixels displaying white in the previous image, pixels displaying white in the next image; Is not driven, and the display state of those pixels is maintained as it is. In this specification, such a writing operation is referred to as differential writing or differential image display operation.

  FIG. 6D shows the input potential of the pixel 10 in the image display step ST13c of the drive sequence SQ13. In the pixel 10 displayed in black in the image display step ST13c, the high-level potential VH is input to the pixel electrode 24 (potential Vs), and is set to a relatively high potential with respect to the common electrode 25 (potential Vcom). On the other hand, in the pixel 10 displaying white, the low level potential VL is input to the pixel electrode 24, so that the potential is relatively low with respect to the common electrode 25. As a result, the pixel 10 in the black display portion and the pixel 10 in the white display portion can be simultaneously driven, and the previous image can be erased and the next image can be simultaneously written.

  In the drive sequence SQ13, an independent erasing step is not provided, and the next image is displayed in the form of overwriting the display image on the display unit 150. Therefore, the image can be switched at a very high speed. On the other hand, since only the pixels 10 having different gradations are rewritten, the afterimage is much more likely to occur when driven by the drive sequence SQ13 than when driven by the drive sequence SQ11.

  Returning again to FIG. In the page switching process of this embodiment, in step S104 shown in FIG. 4, the CPU 102 refers to the table (Table 1) using the control value c, and in the subsequent step S105, sets the drive sequence acquired from the table.

  If the drive sequence is set in step S105, in the subsequent step S106, the CPU 102 determines image data to be displayed based on information about the operated button, and a panel including the image data and the set value of the drive sequence. A drive request is generated and output to the display controller 110. Thereafter, when the process proceeds to step S107, the CPU 102 monitors whether or not the image display operation in the electro-optical panel 112 is completed, and interrupts the process until the panel driving is completed.

  On the other hand, the display controller 110 that has received the panel drive request causes the electro-optical panel 112 to display the image data of the next image included in the panel drive request in accordance with the drive sequence set in the panel drive request.

  Here, an example of an operation for displaying an image on the electro-optical panel 112 will be described. In the following description, it is assumed that the drive sequence SQ11 is set in the panel drive request output to the display unit control device 110.

  In the above example, the overall control unit 140 of the display unit control device 110 outputs the received image data of the next image to the image data write control unit 141 and executes the inversion erasing step ST11 of the drive sequence SQ11. The command is output to the timing signal generation unit 142 and the common power supply control unit 143.

  The image data writing control unit 141 stores the received image data of the next image in the next image holding unit 121 of the storage device 111 via the storage device control unit 144. At this time, the previous image holding unit 120 holds the image data of the currently displayed document page.

The timing signal generation unit 142 outputs a command for causing the image data read control unit 145 to read the image data (image data of the previous image) used in the reverse erasing step ST11 from the previous image holding unit 120 of the storage device 111. . The image data read control unit 145 acquires the image data of the previous image from the previous image holding unit 120 via the storage device control unit 144 and outputs it to the image signal generation unit 146. The image signal generation unit 146 generates an image signal using an inverted image of the input image data of the previous image, and outputs the generated image signal to the data line driving circuit 152 together with the timing signal. The selection signal generation unit 147 generates a selection signal under the control of the timing signal generation unit 142 and outputs the generated selection signal to the scanning line driving circuit 151 together with the timing signal.
The common power supply control unit 143 outputs a command for supplying the reference potential GND to the common electrode 25 to the common power supply 163.

  In the electro-optical panel 112, an image signal based on an inverted image of the previous image is applied to the pixel electrode 24 of the pixel 10 by the scanning line driving circuit 151 to which the selection signal is input and the data line driving circuit 152 to which the image signal is input. Is entered. Further, the reference potential GND is input to the common electrode 25. As a result, the pixels 10 that were displayed in white when the previous image was displayed are shifted to black display. That is, the reverse erasing step ST11 is executed, and the entire image of the display unit 150 is displayed in black so that the previous image is erased.

Next, the overall control unit 140 outputs a command for executing the all white erasing step ST12 to the timing signal generation unit 142 and the common power supply control unit 143.
The timing signal generation unit 142 controls the image signal generation unit 146 and the selection signal generation unit 147, causes the image signal generation unit 146 to generate the image signal used in the all white erasing step ST12, and generates the generated image signal together with the timing signal. The data line driving circuit 152 outputs the data. In addition, the selection signal generation unit 147 generates a selection signal and outputs the generated selection signal to the scanning line driver circuit 151 together with the timing signal.

  In the electro-optical panel 112, an image signal having a low level potential is applied to the pixel electrodes 24 of all the pixels 10 by the scanning line driving circuit 151 to which the selection signal is input and the data line driving circuit 152 to which the image signal is input. The reference potential GND is input from the common power source 163 to the common electrode 25. That is, the all white erasing step ST12 is executed, and the entire surface of the display unit 150 is displayed in white.

Next, the overall control unit 140 outputs a command for executing the image display step ST13 to the timing signal generation unit 142 and the common power supply control unit 143.
The timing signal generation unit 142 outputs a command to the image data read control unit 145 to read the image data (image data of the next image) used in the image display step ST13 from the next image holding unit 121 of the storage device 111. . The image data read control unit 145 acquires the image data of the next image from the next image holding unit 121 via the storage device control unit 144 and outputs the image data to the image signal generation unit 146. The image signal generation unit 146 generates an image signal using the input image data of the next image, and outputs the generated image signal to the data line driving circuit 152 together with the timing signal. The selection signal generation unit 147 generates a selection signal under the control of the timing signal generation unit 142 and outputs the generated selection signal to the scanning line driving circuit 151 together with the timing signal. In addition, the common power supply control unit 143 outputs a command for supplying the reference potential GND to the common electrode 25 to the common power supply 163.

  In the electro-optical panel 112, a high-level potential is applied to the pixel electrode 24 of the pixel 10 to be displayed black by the scanning line driving circuit 151 to which the selection signal is input and the data line driving circuit 152 to which the image signal is input. An image signal is input, and a reference potential GND is input from the common power supply 163 to the common electrode 25. That is, the image display step ST <b> 13 is executed, and a part of the pixels 10 of the display unit 150 that is displayed in white is changed to black display, whereby the next image is displayed on the display unit 150.

When the display of the next image is finished, the CPU 102 resumes the page switching process shown in FIG.
In step S108, the CPU 102 updates the control value c to a value obtained by subtracting 1 and returns the process to step S103. Then, the processing from step S103 to step S108 is repeated until it is determined in step S103 that the control value c is 0. That is, the image is rewritten by the number of times corresponding to the initial value of the control value c set in the pulse counter 114, and a plurality of pages are continuously displayed. At this time, in step S105, one of the drive sequences SQ11 to SQ13 is selected according to the control value c that changes over time, and therefore, the electro-optical panel 112 determines the remaining number of pages to be displayed. Different display operations are performed accordingly.

In the electronic book reader 100 according to the present embodiment described above, when the button of the input device 113 is continuously pressed, an initial value of the control value c corresponding to the number of times the button is pressed is set and the control is performed. The number of pages corresponding to the value c is sequentially displayed.
Each time one page is displayed, that is, every time an image is rewritten, an operation for reducing the control value c by 1 is performed, and a different drive sequence can be set according to the value of the control value c.

  Specifically, when the control value c is a relatively large value (c ≧ N), the driving sequence SQ13 that simultaneously deletes the previous image and displays the next image is selected. That is, when the remaining number of pages to be displayed is large, the display speed is the fastest and the drive sequence SQ13 that does not cause flashing of the display unit 150 is selected. In the drive sequence SQ13, an afterimage is likely to occur because the image is overwritten on the display unit 150. However, the drive sequence SQ13 is immediately switched to another page, so that the user is not uncomfortable.

  On the other hand, when the control value c is an intermediate value (M ≦ c <N), the drive sequence SQ12 (SQ12A or SQ12B) for performing image display after performing one erase is selected. That is, when the remaining number of pages to be displayed is reduced, the drive sequence SQ12 that is slower than the drive sequence SQ13 but provides a display with less afterimage as compared with the drive sequence SQ13 is selected. This makes it easier for the user to visually recognize the contents of the page.

  When the control value c is a small value (1 ≦ c <M), the drive sequence SQ11 for displaying the next image after performing the erasing operation twice is selected. When the control value c is at least equal to the lower limit value of the control value c for rewriting an image, the drive sequence SQ11 is selected. That is, at least on the last page to be displayed, the drive sequence SQ11 that provides a high-quality display with almost no afterimage is selected. In the drive sequence SQ11, since the number of steps is large, the display speed is the slowest, and flushing due to full white display and full black display occurs, but the user can clearly see the contents of the target page.

As described above, according to the electronic book reader 100 of the present embodiment, a driving sequence capable of high-speed image display is used when continuously feeding pages, and display quality is given priority on the last page where the display is fixed. Since the above drive sequence is used, both high-speed page feed and high-quality display can be achieved.
In this embodiment, the control value c is an integer, and the lower limit value of the control value c for rewriting the image is 1. However, the lower limit value of the control value c for rewriting the image is not limited to 1. Absent. Further, the control value c need not be an integer.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings.
In the second embodiment, the data table referred to in step S104 and the operation configuration in each driving sequence are changed. Since the configuration other than the above is the same as that of the first embodiment, detailed description is omitted. .

  The electro-optical device according to the second embodiment has a configuration in which the potential of the common electrode 25 is changed according to the gradation to be displayed on the pixel 10. Details will be described below.

  Table 3 is a table showing an outline of the data table referred to in step S104. Table 4 is a table showing the configuration of the drive sequence shown in Table 3. FIG. 8 is a diagram showing drive waveforms in each operation shown in Table 4.

In Table 3, N is a natural number of 2 or more, and is a constant set appropriately.
In the data table shown in Table 3, the value of the control value c is classified into two levels, and the drive sequences SQ21 and SQ22 are associated with each level. The CPU 102 refers to the data table using the control value c acquired in step S102, and acquires the drive sequence SQ21 or SQ22 corresponding to the level to which the control value c belongs.
For example, when N = 2, the drive sequence SQ22 is selected when the control value c is 2 or more, and the drive sequence SQ21 is selected only when the control value c is 1.

  As shown in Table 4, the drive sequences SQ21 and SQ22 differ in the configuration of the operations executed in the electro-optical panel 112. Hereinafter, each drive sequence will be described with reference to Table 4 and FIG.

<Drive sequence SQ21>
The drive sequence SQ21 is a drive sequence selected when the control value c belongs to the first level (1 ≦ c <N). As shown in Table 4, the inversion erase step (first erase operation) and , An all white erasing step (second erasing operation) and an image displaying step (image displaying operation). Further, FIG. 8A shows potentials respectively input to the pixel electrode 24 and the common electrode 25 in one pixel 10 of the display unit 150, ST21 is an inversion erasing step, ST22 is an all white erasing step, ST23 corresponds to each image display step.

Similar to the reverse erase step ST11, the reverse erase step ST21 writes black to the pixels displaying white in the image (previous image) displayed on the electro-optical panel 112 immediately before the page switching process. The operation of shifting the entire surface (all pixels) of the display unit 150 to black display. In the inversion erasing step ST21 shown in FIG. 8A, the high level potential VH is input to the pixel electrode 24 (potential Vs), while the low level potential VL is input to the common electrode 25 (potential Vcom). As a result, the pixel electrode 24 is set to a high potential with respect to the common electrode 25, and the pixel 10 shifts from white display to black display.
In the inversion erasing step ST21, the pixel 10 that has been displayed black in the previous image is not driven. Therefore, the pixel electrode 24 of the pixel 10 has the same potential (low level potential VL) as the potential Vcom of the common electrode 25. Entered.

  Next, in the all white erasing step ST22, an operation of displaying the entire surface of the display unit 150 in white is executed. As shown in FIG. 8A, in the all white erasing step ST22, the low level potential VL is input to the pixel electrodes 24 of all the pixels 10, while the high level potential VH is input to the common electrode 25. As a result, the pixel electrode 24 is held at a low potential with respect to the common electrode 25 (potential Vcom), and all the pixels 10 are displayed in white.

Next, in the image display step ST23, display based on image data of an image (next image) to be displayed next on the display unit 150 is performed. The image display step ST23 in the drive sequence SQ21 is monochrome writing similar to the image display step ST13 according to the first embodiment. That is, the next image is displayed by drawing only the black display portion of the next image on the display unit 150 that is displayed in white on the entire white in the all white erasing step ST22.
In the pixel 10 displayed in black in the image display step ST23, as shown in FIG. 8A, the high level potential VH is input to the pixel electrode 24, and the low level potential VL is input to the common electrode 25. On the other hand, the same low level potential VL as the potential Vcom of the common electrode 25 is input to the pixel electrode 24 of the pixel 10 that maintains white display in the image display step ST23.

<Drive sequence SQ22>
The drive sequence SQ22 is a drive sequence that is selected when the control value c belongs to the second level (c ≧ N). As shown in Table 4, the reverse erase step (erase operation) and the image display step ( Image display operation).
8B and 8C show two types of driving sequences SQ22 (SQ22A, SQ22B), and the pixel electrode 24 and the common electrode 25 in one pixel 10 of the display unit 150 for each mode. The input waveform to is shown. In FIG. 8, ST21a and ST21b correspond to the reverse erasing step, and ST23a and ST23b correspond to the image display step, respectively.

First, in the inversion erasing step ST21a of the drive sequence SQ22A shown in FIG. 8B, for the pixels displaying white in the image (previous image) displayed on the electro-optical panel 112 immediately before the page switching process. By writing black, the entire surface (all pixels) of the display unit 150 is shifted to black display (reversed all black erasure).
In the inversion erasing step ST21a shown in FIG. 8B, unlike the first embodiment, the high level potential VH is input to the pixel electrode 24 (potential Vs) and the low level potential VL is applied to the common electrode 25 (potential Vcom). Is input, the pixel 10 is displayed in black. At this time, in the pixel 10 displayed in black in the previous image, the same low level potential VL as the potential Vcom of the common electrode 25 is input to the pixel electrode 24, and the pixel 10 is not driven.

  Next, in the image display step ST23a, display based on the image data of the next image to be displayed on the display unit 150 is performed. Specifically, the white component (white display portion) of the next image is written into the display unit 150 that is black-displayed entirely in the reverse erasing step ST21a. In the pixel 10 that displays white in this step, as shown in FIG. 8B, the low level potential VL is input to the pixel electrode 24 and the high level potential VH is input to the common electrode 25. On the other hand, in the pixel 10 whose display is not changed in the image display step ST <b> 23 a, the same high level potential VH as the potential Vcom of the common electrode 25 is input to the pixel electrode 24.

  On the other hand, in the drive sequence SQ22B, in the inversion erasing step ST21b, the display unit 150 is erased with all white (inverted all white erase) using the inverted image of the previous image, and then the black component of the next image is written in the image display step ST23b. Therefore, as shown in FIG. 8C, in the inversion erasing step ST21b, the low level potential VL is input to the pixel electrode 24 of the driven pixel 10 and the high level potential VH is input to the common electrode 25. In the image display step ST23b, the high level potential VH is input to the pixel electrode 24 of the driven pixel 10, and the low level potential VL is input to the common electrode 25.

  Similarly to the first embodiment, the drive sequence SQ22A and the drive sequence SQ22B only have to include at least one, but may be configured to be switchable according to the scene.

  Also in the electro-optical device according to the first modification described above, when the button of the input device 113 is continuously pressed, an initial value of the control value c corresponding to the number of times the button is pressed is set. The number of pages corresponding to the control value c can be displayed sequentially. Then, every time one page is displayed, that is, every time an image is rewritten, an operation for reducing the control value c by 1 is performed, and a different drive sequence is set according to the value of the control value c.

Specifically, when the control value c is a relatively large value (c ≧ N), the drive sequence SQ22 (SQ22A or SQ22B) for performing image display after performing one erasure is selected, and the image is displayed at high speed. Is displayed. On the other hand, when the control value c is a small value (1 ≦ c <M), the driving sequence SQ21 for displaying the next image after performing the erasing operation twice is selected.
That is, at least the last displayed page can obtain a high-quality display with almost no afterimage.

  As described above, also in the electro-optical device according to the first modified example, the driving sequence capable of high-speed image display is used when continuously feeding pages, and display quality is given priority on the last page where the display is fixed. Since the above drive sequence is used, both high-speed page feed and high-quality display can be achieved.

In the electro-optical device of the first modification, the low level potential VL is input to the common electrode 25 when the pixel 10 is displayed in black, and the high level potential VH is input when the pixel 10 is displayed in white. Therefore, black writing and white writing cannot be performed simultaneously on the display unit 150, and the drive sequence SQ13 of the first embodiment cannot be employed.
On the other hand, since the potential difference between the high level potential VH and the low level potential VL can be used as it is as the potential difference between the pixel electrode 24 and the common electrode 25, compared with the driving method used in the first embodiment, There is an advantage that the drive voltage applied to the electro-optic material layer 26 can be increased.
That is, if the high-level potential VH and the low-level potential VL are the same as those in the first embodiment, the electro-optical material layer 26 has a voltage twice that of the first embodiment in the electro-optical device according to the first modification. Can be applied. Therefore, according to the electro-optical device according to the second embodiment, it is possible to reduce the voltage application time to the electro-optical material layer 26 and display an image at high speed.

(Third embodiment)
Next, the electro-optical device according to the third embodiment has a configuration in which drive sequences for different driving methods of the common electrode 25 are switchable. Hereinafter, the third embodiment will be described in detail.

  Table 5 is a table showing an outline of the data table referred to in step S104. Table 6 is a table showing the configuration of the drive sequence shown in Table 5. FIG. 9 is a diagram showing drive waveforms in each operation shown in Table 6.

In Table 5, N is a natural number of 2 or more, and is a constant set as appropriate.
In the data table shown in Table 5, the value of the control value c is classified into two levels, and the drive sequences SQ31 and SQ32 are associated with each level. The CPU 102 refers to the data table using the control value c acquired in step S102, and acquires the drive sequence SQ31 or SQ32 corresponding to the level to which the control value c belongs.
For example, when N = 2 is set, the drive sequence SQ32 is selected when the control value c is 2 or more, and the drive sequence SQ31 is selected only when the control value c is 1.

  As shown in Table 6, the drive sequences SQ31 and SQ32 differ in the configuration of the operations executed in the electro-optical panel 112. Hereinafter, each drive sequence will be described with reference to Table 6 and FIG.

<Drive sequence SQ31>
The drive sequence SQ31 is a drive sequence selected when the control value c belongs to the first level (1 ≦ c <N). As shown in Table 6, the drive sequence SQ31 is the same as the drive sequence SQ21 in the first modified example. is there.
As shown in FIG. 9A, the drive sequence SQ31 includes a reverse erasing step (first erasing operation) ST31, an all white erasing step (second erasing operation) ST32, and an image displaying step (image displaying operation). It consists of ST33. Since the operation of the electro-optical panel 112 in each step is the same as that of the first modified example, description thereof is omitted here.

<Drive sequence SQ32>
The drive sequence SQ32 is a drive sequence selected when the control value c belongs to the second level (c ≧ N), and as shown in Table 6, is the same as the drive sequence SQ13 in the first embodiment.
As shown in FIG. 9B, the drive sequence SQ32 simultaneously drives the black display pixel 10 and the white display pixel 10 to simultaneously erase the previous image and write the next image ST33a. Consists of. Since the operation of the electro-optical panel 112 in each step is the same as that in the first embodiment, description thereof is omitted here.

  Also in the electro-optical device according to the second modification described above, when the button of the input device 113 is continuously pressed, an initial value of the control value c corresponding to the number of times the button is pressed is set. The number of pages corresponding to the control value c can be displayed sequentially. Then, a different drive sequence is set according to the value of the control value c while performing an operation of decreasing the control value c by 1 every time one page is displayed.

  Specifically, when the control value c is a relatively large value (c ≧ N), the drive sequence SQ32 for simultaneously erasing the previous image and displaying the next image is selected, and the image is displayed at high speed. On the other hand, when the control value c is a small value (1 ≦ c <M), the drive sequence SQ31 for displaying the next image after performing the erasing operation twice is selected. That is, at least the last displayed page can obtain a high-quality display with almost no afterimage.

  As described above, also in the electro-optical device according to the second modified example, the driving sequence capable of high-speed image display is used when performing continuous page feed, and display quality is given priority on the last page where the display is fixed. Since the above drive sequence is used, both high-speed page feed and high-quality display can be achieved.

100 electronic book reader (electro-optical device), 101 case, 102 CPU (control unit, calculation unit), 105 page forward button, 106 page return button, 108 enter button, 110 display unit control device, 111 storage device, 112 electricity Optical panel, 113 input device, 114 pulse counter, 115 skip feed button, 116 skip back button, 120 previous image holding unit, 121 next image holding unit, 140 overall control unit, 141 image data write control unit, 142 timing signal generation 143, common power supply control unit, 144 storage device control unit, 145 image data read control unit, 146 image signal generation unit, 147 selection signal generation unit, 150 display unit, 151 scanning line drive circuit, 152 data line drive circuit, 161 VX power supply, 162 VY power supply, 16 Common power supply, c control value, SQ11, SQ12, SQ13, SQ13A, SQ13B, SQ21, SQ22, SQ22A, SQ22B, SQ31, SQ32 driving sequence (a driving method)

According to the driving method of the electro-optical device of the present invention, the number of pages displayed on the display unit is received in accordance with a user's instruction, and each of a part of the plurality of pages is processed by the first driving method based on the number of pages. Display in order on the display unit, and after the display by the first driving method, each of the remaining of the plurality of pages is displayed for one page rather than the time required to display one page by the first driving method. In the second driving method, which takes a long time, the display unit sequentially displays the images.
Further, the driving method of the electro-optical device receives the number of pages displayed on the display unit according to a user's instruction, and uses the first driving method based on the number of pages to part of a plurality of pages. Displaying in order on the display unit; sequentially displaying the remaining part of the plurality of pages on the display unit using the second driving method after the display by the first driving method; Displaying the remaining portions of the remaining pages of the plurality of pages in order on the display unit using a third driving method after the display by the second driving method. The driving method is characterized in that it is slower than the first driving method.
The electro-optical device rewrites an image on the display unit having a plurality of pixels, a control value acquisition unit that acquires an initial value of the control value c used when displaying an image on the display unit, and the display unit. A calculation unit that reduces the control value c every time, a control unit that selects one drive method from a plurality of drive methods according to the value of the control value c, and rewrites an image on the display unit using the selected drive method; The control value c is an integer, and one pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, the first electrode, And an electro-optic material layer sandwiched between the second electrode and the control unit performing a first erasing operation, a second erasing operation, and an image display operation. Method, a second driving method for executing an erasing operation and an image display operation, and display on the display unit And a third driving method for executing a differential image display operation for displaying a differential image between the current image and a new image, and when performing image rewriting a number of times corresponding to the initial value of the control value c, The first driving method is selected when c is a predetermined value L (L is an arbitrary integer) or more and less than a predetermined value M (M is an integer of L + 1 or more), and the control value c is a predetermined value M or more and a predetermined value. The second drive method is selected when the value is less than a value N (N is an integer equal to or greater than M + 1), and the third drive method is selected when the control value c is equal to or greater than a predetermined value N. To do.

Claims (9)

A display unit having a plurality of pixels;
A control value acquisition unit for acquiring an initial value of the control value c used when displaying an image on the display unit;
A calculation unit that reduces the control value c each time the image of the display unit is rewritten;
A control unit that selects one drive method from a plurality of drive methods according to the value of the control value c, and rewrites the image on the display unit using the selected drive method;
An electro-optical device comprising:    The drive method selected from the plurality of drive methods when the control value c is equal to a predetermined lower limit value is slower than the drive method selected when the control value c is another value. The electro-optical device according to claim 1. The control value c is an integer,
One pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, and an electric current sandwiched between the first electrode and the second electrode. And an optical material layer,
The controller includes a first driving method for executing a first erasing operation, a second erasing operation, and an image display operation, a second driving method for executing an erasing operation and an image display operation, and the display A third driving method for executing a difference image display operation for displaying a difference image between an image displayed on the section and a new image,
When the image rewriting is performed a number of times corresponding to the initial value of the control value c, the control value c is greater than or equal to a predetermined value L (L is an arbitrary integer) and less than a predetermined value M (M is an integer equal to or greater than L + 1). When the first driving method is selected and the control value c is equal to or greater than the predetermined value M and less than the predetermined value N (N is an integer equal to or greater than M + 1), the second driving method is selected, and the control value c is equal to the predetermined value. The electro-optical device according to claim 1, wherein the third driving method is selected when N is N or more. The control value c is an integer,
One pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, and an electric current sandwiched between the first electrode and the second electrode. And an optical material layer,
The controller includes a first driving method for executing a first erasing operation, a second erasing operation, and an image display operation, and a second driving method for executing an erasing operation and an image display operation. ,
When the image rewriting is performed a number of times corresponding to the initial value of the control value c, the control value c is greater than or equal to a predetermined value L (L is an arbitrary integer) and less than a predetermined value M (M is an integer equal to or greater than L + 1). The electro-optical device according to claim 1, wherein the first driving method is selected, and the second driving method is selected when the control value c is equal to or greater than a predetermined value M. The second driving method includes:
The image in which at least some of the plurality of pixels are shifted to a second gray level different from the first gray level after the erasing operation for shifting the entire display unit to the first gray level. A first mode for executing a display operation;
After the erasing operation for shifting the entire display unit to the second gradation, the image display operation for executing at least a part of the plurality of pixels to the first gradation is performed. The electro-optical device according to claim 3, wherein the electro-optical device includes two aspects. The control value c is an integer,
One pixel of the plurality of pixels includes a first electrode, a second electrode facing the first electrode, and an electric current sandwiched between the first electrode and the second electrode. And an optical material layer,
The control unit performs a first erasing operation, a second erasing operation, and an image display operation while switching a potential of the second electrode in accordance with a gradation to be displayed, A second driving method for performing a differential image display operation for writing a differential image between an image displayed on the display unit and a next image displayed with the second electrode held at a constant potential;
When the image rewriting is performed a number of times corresponding to the initial value of the control value c, the control value c is greater than or equal to a predetermined value L (L is an arbitrary integer) and less than a predetermined value M (M is an integer equal to or greater than L + 1). The electro-optical device according to claim 1, wherein the first driving method is selected, and the second driving method is selected when the control value c is equal to or greater than a predetermined value M.    The control value acquisition unit measures an input signal pulse supplied from an input device connected to the electro-optical device for a predetermined period, and sets an initial value of the control value c based on the measured number of pulses. The electro-optical device according to any one of claims 1 to 6.    7. The first driving method according to claim 3, wherein the first driving method is slower than a driving method selected from the plurality of driving methods when the control value c is a predetermined value M or more. 2. The electro-optical device according to item 1.    The electro-optical device according to any one of claims 3 to 8, wherein the predetermined value L is 1.

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