JP2008111930A - Information display device and driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image rewriting technique to speed up rewriting of a picture, and to be used for general purpose. <P>SOLUTION: In an information display apparatus 100, flags showing whether each line is blank are stored in a memory about images before and after rewriting. When trying to rewrite a picture, the flags are compared with each other about the images before and after rewriting. When rewriting the picture, processing is skipped about lines both of which are blank before and after rewriting, and rewriting is performed about a line before and after rewriting of which at least either line is not blank. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for rewriting an image in an information display device.

  Memory liquid crystals such as cholesteric liquid crystals are used as display bodies suitable for applications such as electronic books or electronic papers. Cholesteric liquid crystals have the advantage that they can be displayed even when no voltage is applied. On the other hand, cholesteric liquid crystals have a drawback that the rewriting speed is slow. As a technique for improving the rewriting speed of a display device using cholesteric liquid crystal, so-called DDS (Dynamic Drive Scheme) driving described in Patent Document 1 is known. According to the DDS driving, the alignment state of the cholesteric liquid crystal is determined by the power supplied to the liquid crystal in a so-called selection period.

  According to the DDS driving, the selection period, which conventionally required about 10 msec, can be shortened to about 1 msec. However, when trying to increase the resolution of the display device, there is a problem that the display speed is not sufficient even by DDS driving. For example, a display device having 2000 rows of display pixels requires 2 seconds to rewrite one screen even by DDS driving. Here, for example, Patent Document 2 discloses a technique in which information before and after rewriting is compared for each character line, and only character lines that need to be changed are rewritten.

US Pat. No. 5,748,277 JP-A-5-323907

In order to apply the technique described in Patent Document 2, it is necessary for an operator to specify parameters such as the total number of character lines in the entire screen, the number of dots in the character line itself, and the number of dots between character lines. There was a problem of being scarce.
On the other hand, an object of the present invention is to provide an image rewriting technique that can speed up screen rewriting and can be used for general purposes.

In order to solve the above-described problems, the present invention is provided corresponding to the intersection of n rows of scan electrodes and m columns of data electrodes (n and m are positive integers), and a scan voltage is applied to the scan electrodes. Display means having a plurality of display pixels each including a storage liquid crystal layer to which a driving voltage corresponding to the data voltage and the scanning voltage is applied when a data voltage is applied to the data electrode, Data storage means for storing image data including a plurality of pages of images corresponding to the display pixels in the n rows and m columns of the display means, and data indicating the gradation values of the display pixels in the n rows and m columns of the display means And a gradation of at least one row of display pixels in one page image corresponding to n rows and m columns of display pixels of the display means from the image data stored in the data storage means Data indicating the value An image generation unit to generate, a gradation value of target data corresponding to one row of the data generated by the image generation unit, and the target data and row of data stored in the page image storage unit Are stored in the page image storage means, the area acquisition means for acquiring the target area, which is the area within the range of the predetermined gradation values, Display driving means for applying a data voltage to the data line according to data, rewriting display pixels for rows not belonging to the target region, and skipping rewriting of display pixels for rows belonging to the target region An information display device is provided.
According to this information display device, screen rewriting is performed only in regions other than the target region, so that screen rewriting can be speeded up. Further, according to this information display device, power consumption can be reduced by skipping unnecessary rewriting.

In a preferred aspect, in the information display device, the area acquisition unit specifies the target data in a predetermined order from the data generated by the image generation unit, and the gradation value of the target data and the reference data The target area may be acquired by comparing the gradation value.
According to this information display device, the target area is determined according to the gradation value of the target data and the gradation value of the reference data.

In another preferred aspect, the information display device includes a first row of data generated by the image generation unit, the data including continuous rows whose gradation values are within a predetermined range from a predetermined start row. 1st specifying means for specifying one area, and continuous lines whose gradation values are within a predetermined range from a predetermined starting line, among the data stored in the page image storage means A second specifying unit that specifies a second region consisting of: the region acquisition unit may acquire an overlapping portion of the first region and the second region as the target region.
According to this information display device, an overlapping portion of continuous regions in which a continuous region from a predetermined start line is within a range in which a gradation value is present before and after rewriting is specified as a target region.

In still another preferred embodiment, the information display device may include notification means for notifying that rewriting of the display pixel by the display driving means is completed.
According to this information display device, the user can know that rewriting has been completed.

Further, the present invention is provided corresponding to the intersection of n rows of scanning electrodes and m columns of data electrodes (n and m are positive integers), a scanning voltage is applied to the scanning electrodes, and the data electrodes Display means having a plurality of display pixels including a storage liquid crystal layer to which a drive voltage corresponding to the data voltage and the scanning voltage is applied when a data voltage is applied to each of the display means and n rows of the display means Data storage means for storing image data including images of a plurality of pages corresponding to m columns of display pixels, and page image storage for storing data indicating the gradation values of the n rows and m columns of display pixels of the display means And a method for driving the information display device, wherein the image data stored in the data storage means includes at least one row of images of one page corresponding to the display pixels of n rows and m columns of the display means. Display pixel An image generation step for generating data indicating a tone value; a gradation value of target data corresponding to one row of the generated data; and the target data among data stored in the page image storage means And the step of acquiring the target area, which is the area within the range of the predetermined gradation value, the gradation value of the reference data having the same row position and the page image storage means A display in which a data voltage is applied to the data line according to the data being displayed, display pixels are rewritten for rows that do not belong to the target region, and display pixel rewriting is skipped for rows that belong to the target region A driving method having a driving step is provided.
According to this driving method, screen rewriting is performed only for regions other than the target region, so that screen rewriting can be speeded up.

1. First Embodiment First, a first embodiment of the present invention will be described. The outline of the first embodiment is as follows. For the image before rewriting and the image after rewriting, a flag indicating whether each row is a blank row is stored in the memory. When rewriting the screen, the flags are compared for the images before and after rewriting. When rewriting, processing is skipped for lines that are blank before and after rewriting, and rewriting is performed for lines that are not blank lines before and after rewriting.

1-1. Configuration FIG. 1 is a block diagram showing a functional configuration of an information display apparatus 100 according to the first embodiment of the present invention. The display unit 101 displays information (image). The display unit 101 includes a plurality of display pixels each including a memory liquid crystal layer. The plurality of display pixels are provided corresponding to the intersections of n rows of scanning electrodes and m columns of data electrodes (n and m are positive integers). When a scanning voltage is applied to the scanning electrode and a data voltage is applied to the data electrode, a driving voltage corresponding to the data voltage and the scanning voltage is applied to each display pixel. The data storage unit 102 stores image data indicating an image to be displayed on the display unit 101. The image data includes data indicating a plurality of pages of images. Each of the images of the plurality of pages corresponds to the display pixel of the display unit 101. The data acquisition unit 103 acquires image data from the data storage unit 102. The page image generation unit 104 generates data indicating the gradation values of display pixels in at least one row of the image of one page from the image data acquired by the data acquisition unit 103. In the present embodiment, the page image generation unit 104 generates data for one page (n rows and m columns of display pixels). The page image storage unit 105 stores one page of image data and a skip flag. One page of image data is data indicating the gradation value of each of the display pixels in n rows and m columns. The skip flag is data indicating whether or not drawing is necessary for each predetermined number of rows (drive units).

  The area acquisition unit 106 acquires a target area. The target area refers to the gradation value of the target data corresponding to one row of the data generated by the page image generation unit 104 and the position of the target data and the row of data stored in the page image storage unit 105. Are the regions where the gradation values of the reference data having the same are both within the predetermined gradation value range. The storage control unit 107 stores the data generated by the page image generation unit 104 in the page image storage unit. The display driving unit 108 applies a data voltage and a scanning voltage to the data electrode and the scanning electrode according to the image data stored in the page image storage unit 105.

  FIG. 2 is a block diagram illustrating a hardware configuration of the information display apparatus 100. A CPU (Central Processing Unit) 110 is a control device that controls elements of the information display device 100. A ROM (Read Only Memory) 120 is a storage device that stores programs and data necessary for the operation of the information display device 100. A RAM (Random Access Memory) 130 is a storage device that functions as a work area when the CPU 110 executes a program. A video random access memory (VRAM) 131 is a storage device that stores an image to be displayed on the display device 151. An I / O (Input / Output) 140 is an input / output interface. The key button 141 outputs a signal corresponding to a user operation to the I / O 140.

  The display control unit 150 drives the display device 151 according to the image data stored in the VRAM 131. The display device 151 is a display device having a memory liquid crystal layer such as a cholesteric liquid crystal. The power control unit 160 is a control device that controls the supply of power from the battery 161. The battery 161 is a secondary battery such as a Ni—Cd battery or a Li ion battery. The communication control unit 170 is a control device that controls communication with other devices via a communication IF (Interface) 171. The communication IF 171 is an interface that performs communication conforming to standards such as USB (Universal Serial Bus), Blue Tooth (registered trademark), and wireless LAN (Local Area Network). The storage device control unit 180 is a control device that controls the internal storage device 181 and the removable medium 183. The built-in storage device 181 is a rewritable nonvolatile storage device such as a flash memory. The removable medium 183 is a detachable storage device connected to the information display device 100 via the memory IF 182. The removable medium 183 is, for example, an SD (registered trademark) memory card or a memory stick (registered trademark). The above elements are connected via a bus 190. When the CPU 110 executes the control program stored in the ROM 120, the information display device 100 has the functional configuration shown in FIG.

FIG. 3 is a diagram illustrating a configuration of the display device 151. The display device 151 has an n × m matrix wiring including n rows of scanning electrodes (Y ₁ , Y ₂ ,..., Y _n ) and m columns of data electrodes (X ₁ , X ₂ ,..., X _m ). Note that n and m are positive integers. In this embodiment, since the display device 151 is a so-called passive matrix display device, the scan electrode and the data electrode also function as a scan line and a data line, respectively. An electro-optic element 1511 is formed at the intersection of the scan electrode and the data electrode. The electro-optic element 1511 includes two electrodes (a data electrode (sometimes referred to as a pixel electrode or a segment electrode) and a scanning electrode (sometimes referred to as a common electrode or a common electrode), both of which are not shown). It has an electro-optic layer sealed in between. In the present embodiment, a liquid crystal layer including cholesteric liquid crystal that is memory liquid crystal is used as the electro-optical layer. A memory liquid crystal refers to a liquid crystal capable of maintaining a display without supplying power. The electro-optic element 1511 is applied with a voltage corresponding to a voltage applied to the corresponding scan electrode (hereinafter referred to as “scan voltage”) and a voltage applied to the corresponding data electrode (hereinafter referred to as “data voltage”). . The voltage applied to the electro-optic layer is called “driving voltage”. The optical properties (light application property, light scattering property, etc.) of the electro-optic layer vary depending on the applied voltage. The electro-optical element 1511 forms an image by changing the optical properties of the liquid crystal. Note that one electro-optic element 1511 basically corresponds to one pixel. In the case of a color display that performs color display in the RGB color system, one electro-optic element 1511 corresponds to any one of RGB color components in a certain pixel.

  FIG. 4 is a diagram showing the orientation of the cholesteric liquid crystal. In this embodiment, the electro-optic element 1511 has a cholesteric liquid crystal layer 15111 sandwiched between two transparent electrodes (transparent electrodes 15114 and 15115). Further, the cholesteric liquid crystal layer 15111 and the transparent electrodes 15114 and 15115 are sandwiched between two glass substrates (glass substrates 15112 and 15113). A light absorption layer 15116 is provided below the glass substrate 15113.

  The reflectance of light by the cholesteric liquid crystal layer 15111 varies depending on the alignment state of the cholesteric liquid crystal molecules. FIG. 4A is a diagram showing planar alignment (hereinafter referred to as “P alignment”). In the P orientation state, incident light is reflected. That is, white is displayed. FIG. 4B is a diagram showing focal conic orientation (hereinafter referred to as “F orientation”). In the F orientation state, incident light is almost transmitted. Since the transmitted light is absorbed by the light absorption layer 15116, black is displayed. In this manner, white, black, or an intermediate gradation can be displayed by controlling the alignment state of the cholesteric liquid crystal layer 15111. Cholesteric liquid crystal is a bistable material, and can maintain the P orientation or the F orientation even when no voltage is applied. That is, the display is maintained even when no voltage is applied. In order to switch between the P orientation and the F orientation, the cholesteric liquid crystal layer 15111 needs to be once homeotropically oriented (hereinafter referred to as “H orientation”). FIG. 4C shows the H orientation. The H orientation corresponds to a state in which the helical structure of cholesteric liquid crystal molecules is broken. At this time, incident light is transmitted. Since the H orientation is not a stable state, it exists only when a voltage is applied.

1-2. DDS driving Next, DDS driving will be outlined.
FIG. 5 is a diagram for explaining DDS driving. In the DDS drive, the voltage pattern applied to the electro-optical element 1511 has four periods: a non-selection period (Non-selection phase), a reset period (Preparation phase), a selection period (Selection phase), and a holding period (Evolution phase). It is divided into. Selection periods are assigned to the pixels corresponding to the scanning electrodes Y _{1 to} Y _n in order line by line. According to DDS driving, the alignment state of the cholesteric liquid crystal layer 15111 is determined by the selection period and the subsequent holding period. Prior to the development of DDS driving, the alignment state of the cholesteric liquid crystal layer was determined only by the selection period (hereinafter, this driving method is referred to as “conventional driving”). According to conventional driving, a time of about 50 msec, for example, is required as the selection period. Therefore, for example, it took about 100 seconds to rewrite pixels of 2000 lines. According to the DDS driving, the selection period is shortened to about 1 msec. Therefore, the time required for rewriting pixels of 2000 lines is also shortened to about 2 sec.

  FIG. 6 is a diagram showing an alignment transition of cholesteric liquid crystal in DDS driving. In the reset period, a voltage for causing the P- or F-aligned liquid crystal to be in the H-alignment is applied. Next, in the selection period, a voltage (hereinafter referred to as “selection voltage”) for selecting a required display state (white or black for two gradations, that is, P orientation or F orientation). (Referred to as a driving voltage in the selection period). In this embodiment, the cholesteric liquid crystal layer is transitioned to the H alignment or the transient planar alignment (hereinafter referred to as “TP alignment”) by the selection voltage. The TP alignment is an intermediate state between the H alignment and the P alignment in which the helical structure of the liquid crystal molecules is slightly relaxed. Next, in the holding period, a voltage for holding the required display state (hereinafter referred to as “holding voltage”) is applied. The liquid crystal layer that is H-aligned by the selection voltage maintains the H-alignment. The liquid crystal layer that is TP aligned by the selection voltage is transitioned to the F alignment (black display). Next, in the non-selection period, the voltage is erased (strictly, the voltage may not be zero). The liquid crystal layer that has been H-aligned by the holding voltage is changed to P-alignment (white display).

FIG. 7 is a diagram illustrating a driving voltage waveform in the DDS driving. As shown in FIG. 7, in each of the non-selection period, the reset period, the selection period, and the holding period, voltage patterns including at least two types of voltage values are applied to the scan electrode and the data electrode. The voltages applied to the scan electrodes in the non-selection period, the reset period, the selection period, and the holding period are represented as V _N , V _P , V _S, and V _E , respectively. For example, two types of voltages applied in the non-selection period are distinguished using subscripts such as V _N1 and V _N2 . Subscripts are assigned small numbers in order from the lowest absolute voltage value. The same applies to other periods. FIG. 7 shows V _P1 = 0V, V _P2 = 56V, V _S1 = 0V, V _S2 = 18V, V _S3 = 38V, V _S4 = 56V, V _E1 = 18V, V _E2 = 38V, V _N1 = 9V and V An example in which _N2 = 47V is shown. In this example, voltage patterns including four types of voltage values V _{SEG1 to} V _SEG4 are applied to the data electrodes. _In the example of FIG. _7, a _{V SEG1 = 0V, V SEG2 =} 18V, V SEG3 = 38V and _V SEG4 = 56V. As shown in FIG. 7, in the DDS drive, the effective voltage applied to the electro-optic element is the same during the period other than the selection period, regardless of whether the voltage pattern of the data electrode corresponds to white or black. It is. Only in the selection period, the effective voltage applied to the electro-optic element differs depending on the gradation value to be displayed. In DDS driving, the orientation of the liquid crystal is determined by the effective voltage applied during the selection period. Note that the waveforms and voltage values shown in FIG. 7 are merely examples, and the drive waveforms and voltage values are not limited thereto. Any driving waveform may be used as long as the effective voltage applied to the electro-optic element can be varied according to the gradation value to be displayed only during the selection period. The voltage value may be determined according to the thickness of the cholesteric liquid crystal layer 15111 or the like.

1-3. Operation FIG. 8 is a flowchart showing the operation of the information display apparatus 100 according to the first embodiment. For example, the flow illustrated in FIG. 8 is started when the user operates the key button 141. The event that triggers the start of the flow shown in FIG. 8 is not limited to this and may be any event. First, the CPU 110 of the information display device 100 performs the following processing. The CPU 110 reads image data from the internal storage device 181. The CPU 110 stores the read image data in the RAM 130. CPU 110 generates an image of one page (hereinafter referred to as “page image”).

  In step S100, the CPU 110 initializes a flag table. The “flag table” is a table that stores, for each row of the image before or after rewriting, a flag indicating whether the gradation value of the row is within a predetermined range. In the present embodiment, the flag indicates whether the gradation value of the row is white, that is, a blank row. Hereinafter, this flag table is referred to as “blank line flag table”.

  FIG. 9 is a diagram illustrating a blank line flag table. The blank line flag table is stored in the RAM 130. The RAM 130 stores two blank line flag tables, a blank line flag table (front) and a blank line flag table (rear). The “blank row flag table (front)” stores a blank row flag for image data before rewriting. The “blank row flag table (after)” stores a blank row flag for the rewritten image data. Each blank line flag table has a plurality (n in this embodiment) of data sets including a line number, that is, an identifier for specifying a line, and a blank line flag for the line. In FIG. 9, the flag “ON” indicates that the line is a blank line, and the flag “OFF” indicates that the line is not a blank line.

  This will be described with reference to FIG. The initialization of the flag table in step S100 refers to the following processing, for example. The CPU 110 copies the data stored in the blank line flag table (back) to the blank line flag table (front). That is, the data in the blank line flag table (front) is overwritten with the data in the blank line flag table (after). Next, the CPU 110 rewrites all the blank line flag table (after) flags to “OFF”.

  In step S110, the CPU 110 performs blank line determination. The blank line determination is performed on the specified one line of the image data as a processing target. For example, the processing target rows are specified in order from the smallest row number. The CPU 110 performs a predetermined algorithm operation on the data of the processing target row (hereinafter simply referred to as “target row data”) in the page image data, and determines whether the row is a blank row.

  For example, the following algorithm is used as the blank line determination algorithm. Now, a case where image data is expressed in monochrome 256 gradations will be described as an example. The gradation value 0x00 indicates black, and the gradation value 0xFF indicates white. The CPU 110 calculates a logical product (AND) of gradation values for all pixels belonging to the target row data. When the calculated logical product is equal to 0xFF, the CPU 110 determines that the processing target row is a blank row. When the calculated logical product is not equal to 0xFF, the CPU 110 determines that the processing target row is not a blank row. This algorithm is merely an example, and the present invention is not limited to this.

  In step S120, CPU 110 stores the result of blank line determination in the blank line flag table (after). That is, “ON” is stored in the flag if the processing target line is a blank line, and “OFF” is stored in the flag if it is not a blank line. In step S130, CPU 110 determines whether blank line determination has been completed for all lines of the page image data. When it is determined that blank line determination has not been completed for all lines (step S130: NO), the CPU 110 repeatedly executes the processes of steps S110 to S120. When it is determined that blank line determination has been completed for all lines (step S130: YES), the CPU 110 shifts the processing to step S140.

  In step S <b> 140, the CPU 110 stores page image data in the VRAM 131. In step S150, the display control unit 150 drives the display device 151. That is, the display control unit 150 rewrites the image displayed on the display device 151 according to the page image data stored in the VRAM 131 under the control of the CPU 110. Details are as follows. In the blank line flag table (front) and blank line flag table (rear), the display control unit 150 determines that both blank line flags having the same line number are “ON”, that is, both blank lines are blank lines. Judge if there is. The display control unit 150 rewrites the screen for a line that is determined to be at least one of which is not a blank line. That is, the display control unit 150 applies the selection voltage. The display control unit 150 does not rewrite the screen for the lines that are determined to be both blank lines. That is, the display control unit 150 does not apply the selection voltage. In the example shown in FIG. 9, rewriting is skipped for the first, second, fifth and nth rows, and rewriting is performed for the third, fourth and sixth rows. That is, rewriting is skipped as a target area for lines that are blank before and after rewriting, and rewriting is performed for other areas.

FIG. 10 is a diagram for explaining a driving method according to the present embodiment. FIG. 10 shows a driving method for the seven scanning electrodes Y ₁ to Y ₆ and Y _{n in} order to avoid the drawing from becoming complicated. What is written on the left side of each line is the value of the skip flag. For the scan electrode corresponding to the line with the skip flag “OFF”, the selection voltage is applied in the same manner as in the prior art, but for the scan electrode corresponding to the line with the skip flag “ON”, the scan voltage is not applied for the entire period. A selection voltage is applied. That is, the non-selection period is assigned to all the scan electrodes corresponding to the lines whose skip flag is “ON”.

  As described above, according to the present embodiment, rewriting is not performed for lines that are blank before and after rewriting. That is, the selection voltage is not applied to rows that are blank before and after rewriting. Therefore, the rewriting of the image can be speeded up. Moreover, power consumption is reduced by skipping unnecessary rewriting.

2. Second Embodiment Next, a second embodiment of the present invention will be described. In the second embodiment, common reference numerals are used for elements common to the first embodiment. Further, the description of matters common to the first embodiment is omitted. The outline of the second embodiment is as follows. For the images before and after rewriting, an area that is blank continuously from the end is specified. The overlapping part of these areas is the target area, and the screen is not rewritten.

  FIG. 11 is a flowchart showing an operation according to the second embodiment. The flow shown in FIG. 11 is started when, for example, the user operates the key button 141. The event that triggers the start of the flow shown in FIG. 11 is not limited to this, and any event may be used.

  First, in steps S200 to S204, processing is performed on an image before rewriting. In step S200, CPU 110 initializes counter i. The counter i is a parameter that specifies a row to be processed. Here, counter i is initialized with i = n. Note that n is the number of the bottom line of the image.

  In step S201, the CPU 110 determines whether the i-th row data of the page image data is a blank row. When it is determined that the i-th row is a blank row (step S201: YES), in step S202, the CPU 110 updates the counter i. Here, the counter i is updated with i = i−1. When it is determined that the i-th line is not a blank line (step S201: NO), the CPU 110 shifts the process to step S204. In step S203, the CPU 110 determines whether the counter i satisfies an end condition, i = 0 in this case. When it is determined that the end condition is not satisfied (step S203: NO), the CPU 110 repeatedly executes the processes of steps S201 to S202. When it is determined that the end condition is satisfied (step S203: YES), the CPU 110 shifts the process to step S204.

  In step S204, the CPU 110 determines the value of the parameter Yb with Yb = i. The parameter Yb is a parameter indicating a boundary line of a region where blank lines are continuous in the image before rewriting. That is, all the areas from the predetermined start line, that is, the line corresponding to the initial value of the counter i (here, the nth line or the lowest line) to the line corresponding to the parameter Yb are empty lines. The CPU 110 stores the parameter Yb in the RAM 130.

  In step S <b> 205, the CPU 110 stores the rewritten image (page image data) in the VRAM 131. In steps S206 to S210, the rewritten image is processed. Steps S206 to S210 are performed in the same manner as steps S200 to S204, except that the parameter determined in step S210 is the parameter Ya. The parameter Ya is a parameter indicating a boundary line of a region where blank lines are continuous in the rewritten image. That is, the area from the predetermined start line, that is, the line corresponding to the initial value of the counter i (here, the nth line or the lowest line) to the line corresponding to the parameter Ya is all empty lines. The CPU 110 stores the parameter Ya in the RAM 130.

  In step S211, CPU 110 determines whether Ya and Yb satisfy a condition (here, max (Ya, Yb) = 0) for not rewriting the entire screen. When it is determined that Ya and Yb satisfy this condition (step S211: YES), the CPU 110 ends the process shown in FIG. When it is determined that Ya and Yb do not satisfy this condition (step S211: NO), the CPU 110 rewrites the screen from the first line to the (max (Ya, Yb)) line. Here, max (Ya, Yb) indicates that all rows below that row are blank before and after rewriting.

  FIG. 12 is a diagram illustrating a screen before and after rewriting. As shown in FIG. 12, rewriting is not performed for an area consisting of continuous blank lines before and after rewriting. Therefore, rewriting of the screen can be speeded up. Moreover, power consumption is reduced by skipping unnecessary rewriting.

  In FIG. 11, the processes in steps S200 to S204 may be omitted. This is due to the following reason. For example, when rewriting from the first page to the second page, Ya is determined for the image of the second page. Next, when rewriting from the second page to the third page, the value of the parameter Y has already been determined for the second page. Therefore, CPU110 may perform the process (Yb = Ya) which sets the value of parameter Yb to Ya instead of the process of step S200-S204.

3. Other Embodiments The present invention is not limited to the above-described embodiments, and various modifications can be made.
The information display apparatus 100 may have a function of notifying the user that screen rewriting has been completed. For example, the information display apparatus 100 notifies the user that the rewriting of the screen is completed by sound, light, or vibration. In this case, the information display device 100 includes a device that generates sound, light, or vibration. Alternatively, the information display device 100 may have a display device (sub display) different from the display device 151. Information indicating that the screen rewriting has been completed may be displayed on the sub-display.

  The information display apparatus 100 may have a function of executing the two processes of the first embodiment and the second embodiment described above. In this case, the information display apparatus 100 may have a user interface that instructs the user whether to perform the process described in the first embodiment or the process described in the second embodiment. The information display device 100 performs processing according to the user's selection. Alternatively, the information display apparatus 100 may automatically determine which process is performed based on the displayed image data. The determination is made based on, for example, attribute information of the image data.

  In the above-described embodiment, when all the pixels included in the target row indicate white, the row is determined to be a blank row. However, the blank row determination criterion is limited to this. It is not something. When the gradation value of a pixel of a certain ratio (for example, 99%) or more among the pixels included in the target row is white, it may be determined that the row is a blank row. . Alternatively, “white” does not mean only one specific gradation value, but may mean a gradation value within a certain range. The boundary value that determines the range of “white” may be variable. The boundary value may be input via a user interface. Further, the gradation value serving as a criterion for determination is not limited to “white”. Depending on the structure of the display device 151, “black” or other gradation values may be used as a reference.

  In the above-described embodiment, blank line determination is performed for each line. However, the unit for performing blank line determination is not limited to one line. Blank line determination may be performed for each of a plurality of lines (for example, two lines and three lines).

It is a block diagram which shows the function structure of the information display apparatus 100 which concerns on 1st Embodiment. 2 is a block diagram illustrating a hardware configuration of the information display apparatus 100. FIG. 3 is a diagram showing a configuration of a display device 151. FIG. It is a figure which shows the orientation of a cholesteric liquid crystal. It is a figure explaining DDS drive. It is a figure which shows the orientation transition of the cholesteric liquid crystal in DDS drive. It is a figure which illustrates the drive voltage waveform in DDS drive. It is a flowchart which shows operation | movement of the information display apparatus 100 which concerns on 1st Embodiment. It is a figure which illustrates a blank line flag table. It is a figure explaining the drive method concerning this embodiment. It is a flowchart which shows the operation | movement which concerns on 2nd Embodiment. It is a figure which illustrates the screen before and behind rewriting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Information display apparatus, 101 ... Display part, 102 ... Data storage part, 103 ... Data acquisition part, 104 ... Page image generation part, 105 ... Page image storage part, 106 ... Area acquisition part, 107 ... Storage control part, 108 ... Display drive unit, 110 ... CPU, 120 ... ROM, 130 ... RAM, 131 ... VRAM, 140 ... I / O, 141 ... Key button, 150 ... Display control unit, 151 ... Display device, 160 ... Power supply control unit, 161 ... Battery, 170 ... Communication control unit, 171 ... IF for communication, 180 ... Storage device control unit, 181 ... Built-in storage device, 183 ... Removable media, 190 ... Bus, 1511 ... Electro-optical element, 15111 ... Cholesteric liquid crystal layer, 15112 15113 glass substrate, 15114 15115 transparent electrode, 15116 light absorption layer

Claims (5)

Provided corresponding to the intersection of n rows of scan electrodes and m columns of data electrodes (n and m are positive integers), a scan voltage is applied to the scan electrodes, and a data voltage is applied to the data electrodes Display means having a plurality of display pixels including a storage liquid crystal layer to which a driving voltage corresponding to the data voltage and the scanning voltage is applied,
Data storage means for storing image data including images of a plurality of pages each corresponding to display pixels of n rows and m columns of the display means;
Page image storage means for storing data indicating the gradation value of each of the display pixels in the n rows and m columns of the display means;
Image generation for generating, from the image data stored in the data storage means, data indicating the gradation values of at least one row of display pixels of one page image corresponding to the display pixels of n rows and m columns of the display means Means,
Of the data generated by the image generation means, the gradation value of the target data corresponding to one row, and the reference of the target data and the row position of the data stored in the page image storage means are the same Area acquisition means for acquiring a target area, which is an area in which the gradation values of the data are both within a predetermined gradation value range;
A data voltage is applied to the data line in accordance with the data stored in the page image storage means, display pixels are rewritten for rows that do not belong to the target region, and for rows that belong to the target region. And an information display device having display drive means for skipping rewriting of display pixels. The region acquisition unit specifies target data in a predetermined order from the data generated by the image generation unit, and compares the gradation value of the target data with the gradation value of the reference data, thereby The information display device according to claim 1, wherein a target region is acquired. A first specifying means for specifying a first area consisting of consecutive rows whose gradation values are within a predetermined range from a predetermined start row of the data generated by the image generating means; ,
A second specification for specifying a second region consisting of continuous rows whose gradation values are within a predetermined range from a predetermined start row of the data stored in the page image storage means Means and
The information display device according to claim 1, wherein the area acquisition unit acquires an overlapping portion of the first area and the second area as the target area. The information display device according to claim 1, further comprising notification means for notifying that rewriting of the display pixel by the display driving means is completed. Provided corresponding to the intersection of n rows of scan electrodes and m columns of data electrodes (n and m are positive integers), a scan voltage is applied to the scan electrodes, and a data voltage is applied to the data electrodes Display means having a plurality of display pixels including a storage liquid crystal layer to which a driving voltage corresponding to the data voltage and the scanning voltage is applied, and each of the display means has n rows and m columns of display pixels. Information display comprising: data storage means for storing image data including images of a plurality of corresponding pages; and page image storage means for storing data indicating each gradation value of display pixels in the n rows and m columns of the display means. A method for driving an apparatus, comprising:
Image generation for generating, from the image data stored in the data storage means, data indicating the gradation values of at least one row of display pixels of one page image corresponding to the display pixels of n rows and m columns of the display means Steps,
Among the generated data, the gradation value of the target data corresponding to one row, and the gradation of the reference data having the same row position as the target data among the data stored in the page image storage means An area acquisition step for acquiring a target area, which is an area whose values are both within a predetermined gradation value range;
A data voltage is applied to the data line in accordance with the data stored in the page image storage means, display pixels are rewritten for rows that do not belong to the target region, and for rows that belong to the target region. A display driving step for skipping rewriting of display pixels.

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