JP2004206135A - Liquid crystal display method and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display method capable of enhancing moving picture display grade by preventing light leakage of a backlight and reducing the blotting of an image edge. <P>SOLUTION: A selection signal is supplied to one row line among row lines from n-th line to n+m-1-th line ((n) and (m) is a positive integer) among a plurality of row lines, at the same time, a data signal is supplied to each of a plurality of column lines and, thereby, a prescribed data signal is supplied to a pixel corresponding to the one row line among a plurality of pixels. After or before this, a selection signal is supplied to at least one row line among row lines from first line to 1+m-1-th line among a plurality of row lines, at the same time, a black display signal is supplied to each of a plurality of column lines and, thereby, the black display signal is supplied to a pixel corresponding to at least the one row line among a plurality of the pixels. Thereby, the prescribed data signal and black display signal are supplied to each of a plurality of the pixels in one frame term. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display method and a liquid crystal display device excellent in displaying moving images.

  Conventionally, there is an active matrix type liquid crystal display device. In this active matrix type liquid crystal display device, as shown in FIG. 31, every time data of one horizontal line is sampled from a video signal to a sampling memory 2 by a source driver 1, the sampled data is stored in a holding memory 3. store. On the liquid crystal panel side, a horizontal line composed of picture element rows to which data is to be written is selected by a gate driver (not shown), and the TFT (thin film transistor) of the selected picture element is turned on. After that, the data signal for one horizontal line stored in the holding memory 3 is DA-converted by the DA converter 4 and written via the source line 6 to all picture elements constituting the selected horizontal line.

  The above-described operation is performed on all the horizontal lines, and the writing of the video of one screen is completed. By repeating this as one frame, various images can be displayed. An active matrix type liquid crystal display device performing such a display operation is applied to a display section of a word processor or a notebook computer, or a television.

  In the conventional active matrix type liquid crystal display device, since the response speed of the liquid crystal, particularly the response speed between halftones, is slower than 16.7 ms which is the time of one frame, an afterimage is generated in the case of displaying a moving image. There is a problem of display quality deterioration such as being seen.

  While the TFT is not selected, the data signal written to the corresponding picture element is kept held. For this reason, even if the response speed of the liquid crystal is increased, there is an afterimage on the retina due to the human gaze tracking the moving image. As a result, there is a problem that display quality is deteriorated.

  Then, in order to solve each of the above problems, the following liquid crystal display methods have been proposed (Patent Document 1 and Non-Patent Document 1). In Patent Document 1, the screen is divided into upper and lower parts, and in the first half of the frame time, the upper screen is signal-scanned and the lower screen is scanned with a black signal (blanking). In the latter half of the frame time, the upper screen is scanned with a black signal (blanking) and the lower screen is simultaneously scanned with a signal.

  In Non-Patent Document 1, a screen is divided into upper and lower parts and one frame time is divided into time slots of the number of lines of the entire screen. In the first slot, the upper screen is signal-scanned at the same time as the lower screen. In the second slot, the upper screen is scanned with a black signal (blanking), and the lower screen is also scanned with a black signal (blanking). In this manner, signal scanning and black signal (blanking) scanning are sequentially repeated for each slot.

According to each of the above-described liquid crystal display methods, when focusing on one picture element, there is always both an image display period and a black display period during one frame time, and particularly, the presence of the black display period causes the preceding and following frame data to be mixed. It is possible to display an image without any change. Therefore, the display performance of moving images can be improved.
JP-A-11-109921 "New Moving Picture LCD Using Pi-Cell", Journal of the Liquid Crystal Society of Japan, 1999, vol. 3, No. 2

  However, the liquid crystal display method disclosed in Non-Patent Document 1 has the following problem. That is, one frame time is divided into time slots of the number of lines of the entire screen, and the screen is further divided into upper and lower parts. In the first slot, the upper screen is signal-scanned at the same time as the lower screen. On the other hand, in the second slot, the upper screen is scanned with a black signal (blanking) and the lower screen is also scanned with a black signal (blanking). In this manner, the signal scanning and the black signal (blanking) scanning are sequentially repeated for each slot. Therefore, it is necessary to scan the lower screen at the same time as starting to scan the upper screen, and it is necessary to store one line of image data once. Therefore, there is a problem that the circuit becomes complicated and leads to an increase in cost.

  Further, the liquid crystal display method disclosed in Patent Document 1 has a similar problem. That is, one frame time is divided into the first half and the second half, and the screen is further divided into upper and lower parts. In the first half of one frame time, the upper screen is scanned with a signal and the lower screen is scanned with a black signal (blanking). On the other hand, in the latter half of one frame time, the upper screen is scanned with a black signal (blanking) and simultaneously the lower screen is scanned with a signal. In this case, the storage of the image data as in Non-patent Document 1 is not necessary, but the problem that the circuit is complicated and the cost is increased due to the screen division still occurs.

  Needless to say, when the screen is divided, for example, the source driver is required twice in the upper and lower directions, and the cost is increased.

  Therefore, an object of the present invention is to provide a moving image by the minimum improvement of the conventional liquid crystal display device without performing screen division as in Patent Document 1 and Non-Patent Document 1, and without requiring a special screen storage device. An object of the present invention is to provide a liquid crystal display method and a liquid crystal display device that can improve display quality.

  In order to achieve the above object, a first aspect of the present invention is to supply a data signal to a plurality of column lines arranged in parallel to each other and to select a plurality of row lines arranged in parallel in a direction intersecting the column lines. A liquid crystal display method for supplying a signal and displaying an image on a liquid crystal picture element at or near an intersection of a column line supplied with the data signal and a row line supplied with the selection signal. , N (n: a positive integer), the selection signal is supplied to the row line, and the data signal is supplied to the column line, and the picture related to the intersection of the n-th row line and each column line is displayed. A pixel is used to display an image based on the data signal, and then, when m is a positive integer, the selection signal is supplied to the (n + m) -th row line, and a black display signal for displaying a black image on a picture element is provided. Is supplied to the column lines, and the (n + m) -th row line and each column line are The black image is displayed on the picture element relating to the difference position, and the display operation of the image based on the data signal and the display operation of the black image are repeated while sequentially shifting the row line supplying the selection signal, and the selection signal is displayed. If the (n + m) -th row line to be supplied exceeds the last row line, the process returns to the first row line and displays an image based on the data signal and a black image for each of all picture elements within one frame period. It is characterized by:

  According to the above configuration, unlike the case of Patent Document 1 and Non-patent Document 1, the supply of the data signal to the column line and the supply of the black display signal are performed alternately, and the row line that supplies the selection signal is the same as the above. In synchronization with the signal supply, n is sequentially increased as n, n + m, n + 1, n + m + 1, n + 2, n + m + 2,. Thus, without dividing the screen or using a circuit for storing image data of one screen, the data signal is written to all the picture elements, and after a predetermined time corresponding to m has elapsed, A black display signal is supplied, and the state in which the black display signal is written is maintained until a new image data signal is written in the next frame, and a black image is displayed. Therefore, when the picture element performing the white display changes to the black display in the next frame, the black image is already displayed before the black display signal is written, and the backlight does not leak. It is.

  Further, the edge of the video in the moving image moves at the change of the frame and stops during the frame period. However, since a human perceives that an image is moving smoothly, there are a period in which the edge of the image is ahead of and behind the line of sight of the human, and the image edge appears blurred. However, in the present invention, as described above, the picture element displaying the image is displayed in black before the next data signal is applied, and the image disappears. The period before the line of sight and the period after the line of sight are shortened, and blurring of the edge of the image is reduced. Thus, the moving image display quality is improved.

  According to a second aspect of the present invention, a data signal is supplied to a plurality of column lines arranged in parallel with each other, and a selection signal is supplied to a plurality of row lines arranged in parallel with each other in a direction intersecting the column lines. , A liquid crystal display method for displaying an image on a liquid crystal picture element at or near an intersection of a column line to which the data signal is supplied and a row line to which the selection signal is supplied, comprising: Supplying the selection signal to the line, and supplying the data signal to the column line, and displaying an image based on the data signal on a picture element at an intersection between the n-th row line and each column line; Next, the selection signal is simultaneously supplied to a plurality of row lines different from the n-th row line, and a black display signal for displaying a black image on a picture element is supplied to the column line. The above black image is displayed on the picture element related to the intersection position of multiple row lines and each column line The display operation of the image based on the data signal and the display operation of the black image are repeated while sequentially shifting the row line supplying the selection signal, and the plurality of row lines supplying the selection signal simultaneously constitute the last row line. If it exceeds, returning to the first row line, an image based on the data signal and a black image are displayed for each of all picture elements within one frame period.

  According to the above configuration, a black display signal is supplied to all picture elements a plurality of times in the latter half of one frame period. Therefore, even if the black display signal supply time is such that a single black display signal supply is not enough to perform a sufficient black image display, the black display is reliably performed by repeating the black display signal supply a plurality of times. . Thus, even when the pixel density of the display panel is high and the number of lines is large, and the black display signal supply time is not sufficient, high-quality moving image display with no backlight leakage is performed. .

  In the liquid crystal display method according to the second aspect, the plurality of row lines are (n + α · m) (α = 1, 2,..., P (p: positive integer)). It is desirable.

  According to the above configuration, when focusing on one horizontal line, black display is repeatedly performed every m scans. In this way, the display content of the immediately preceding frame is not affected by the dielectric constant of the liquid crystal, and higher-quality display is performed.

  Further, in the liquid crystal display method according to the second aspect, the plurality of row lines are changed from (n + α · m) th row to (n + α · m + k−1) (α = 1, 2,..., P (p, k: (Positive integer)) It is desirable to use the first line.

  According to the above configuration, when focusing on a certain horizontal line, black display is repeatedly performed k times every m scans, and the influence of the display content of the immediately preceding frame is further eliminated.

  In the liquid crystal display method according to the first invention or the second invention, it is preferable that a supply time of the data signal is equal to a supply time of the black display signal.

  According to the above configuration, since the supply time of the data signal is equal to the supply time of the black display signal, the supply of the data signal and the supply of the black display signal can be switched by a very simple switching control process. .

  In the liquid crystal display method according to the first invention or the second invention, it is preferable that a supply time of the data signal is longer than a supply time of the black display signal.

  According to the above configuration, it is possible to cope with a case where the data signal supply time is not sufficient because the display panel has a high pixel density and a large number of row lines.

In the liquid crystal display method according to the first or second aspect of the present invention, it is preferable that the value of m is set so as to satisfy the following relationship.
fxm / N> t
Here, N: number of lines f: one frame time t: response time of the liquid crystal when switching from white display to black display

  According to the above configuration, the supply time of the black display signal in one frame period is set to be equal to or longer than the response time of the liquid crystal when switching from white display to black display. In this way, even for a picture element for which a white image is displayed based on the data signal, black display is reliably performed until the next data signal is applied.

In the liquid crystal display method according to the first or second aspect, it is preferable that the value of k is set so as to satisfy the following relationship.
T × k ≧ T ₀
Here, T: one supply time of the black display signal T ₀ : the shortest time of the black display signal which can completely switch the white display to the black display

  According to the above configuration, the supply time of the black display signal in one frame period is set to be equal to or longer than the shortest time during which the white display can be switched to the black display by supplying the black display signal k times. Thus, in the case where the black display signal is supplied k times repeatedly because the supply time of the black display signal is insufficient, even if the picture element displays a white image based on the data signal, Black display is performed reliably until the signal is applied.

In the liquid crystal display method according to the first or second invention, the voltage Vd when the data signal is a data signal for black display and the voltage Vr of the black display signal satisfy the following relationship. It is desirable to set as follows.
In the case of positive polarity with respect to the potential level of the counter electrode, Vd <Vr in normally white, and Vd> Vr in normally black.
In the case of a negative polarity with respect to the potential level of the counter electrode, Vd> Vr in normally white and Vd <Vr in normally black.

  According to the above configuration, even if the supply time of the black display signal is insufficient and sufficient black display cannot be performed, the voltage of the black display signal is set to be relatively large (small) so that the black display signal can be surely obtained. Display is performed.

  In a third aspect of the present invention, a plurality of column lines arranged in parallel with each other, a plurality of row lines arranged in parallel with each other in a direction intersecting with the column electrode, an intersection position between the column line and the row line, or A liquid crystal display device having a display panel on which at least a picture element made of liquid crystal near an intersection position is formed, a column line driver for supplying a data signal to the column line, and a row line driver for supplying a selection signal to the row line. A display control unit that supplies a video signal and a control signal to the column line driver, and supplies a control signal to the row line driver to control an image display operation on the display panel; A black display signal generating means for generating a black display signal for display; a data signal provided on the column line driver based on a video signal from the display control unit; and a black signal from the black display signal generating means. The display control unit supplies the control signal for sequentially selecting the row line to the row line driver, and the changeover switch transmits the data signal to the row line driver. When the selection is made, the selection signal is supplied to the n-th row line, while when the switch is selecting the black display signal, the selection signal is supplied to the (n + m) -th row line. Features.

  According to the above configuration, the row line driver and the column line driver are controlled as follows based on the control signal from the display control. That is, when a data signal is selected by the changeover switch of the column line driver and supplied to the column line, the nth row line is selected by the row line driver. On the other hand, when the black display signal is selected by the changeover switch and supplied to the column line, the (n + m) -th row line is selected. Thus, a data signal is written to all picture elements, a black display signal is supplied after a lapse of a predetermined time corresponding to m, and a black display signal is displayed until a new image data signal is written in the next frame. The state in which the signal is written is maintained, and a black image is displayed. Therefore, when the picture element performing the white display changes to the black display in the next frame, the black image is already displayed before the black display signal is written, and the backlight does not leak. It is.

  According to a fourth aspect of the present invention, there are provided a plurality of column lines arranged in parallel with each other, a plurality of row lines arranged in parallel with each other in a direction intersecting the column electrodes, an intersection position between the column line and the row line, or A liquid crystal display device having a display panel on which at least a picture element made of liquid crystal near an intersection position is formed, a column line driver for supplying a data signal to the column line, and a row line driver for supplying a selection signal to the row line. A display control unit that supplies a video signal and a control signal to the column line driver, and supplies a control signal to the row line driver to control an image display operation on the display panel; A black display signal generating means for generating a black display signal for display; a data signal provided on the column line driver based on a video signal from the display control unit; and a black signal from the black display signal generating means. The display control unit supplies the control signal for sequentially selecting the row line to the row line driver, and the changeover switch transmits the data signal to the row line driver. When the selection is made, the selection signal is supplied to the n-th row line, while when the changeover switch selects the black display signal, the selection signal is supplied to a plurality of row lines different from the n-th row line. It is characterized in that a selection signal is supplied.

  According to the above configuration, the row line driver and the column line driver are controlled as follows based on the control signal from the display control. That is, when a data signal is selected by the changeover switch of the column line driver and supplied to the column line, the nth row line is selected by the row line driver. On the other hand, when the black display signal is selected by the switch and supplied to the column line, a plurality of row lines different from the n-th line line are selected. Therefore, even if the black display signal supply time is such that a single black display signal supply is not enough to perform a sufficient black image display, the black display is reliably performed by repeating the black display signal supply a plurality of times. . Thus, even when the pixel density of the display panel is high and the number of lines is large, and the black display signal supply time is not sufficient, high-quality moving image display with no backlight leakage is performed. .

  Further, in the liquid crystal display device according to the third or fourth invention, the row line is divided into L (L: a positive integer) blocks for every m lines, and the row line driver is arranged in a row of each block. Desirably, it is composed of L partial row line drivers that supply select signals to the lines.

  According to the configuration, when a data signal is supplied to the column line by the changeover switch, the n-th row line connected to the partial row line driver is selected by one partial row line driver. . On the other hand, when a black display signal is supplied to the column line by the changeover switch, the n-th row line connected to the partial row line driver is connected to the partial row line driver located in the rear column of the partial row line driver. Is selected. Thus, the selection operation of (n + m) row lines is performed by a simple control.

  Further, in the liquid crystal display device according to the third invention or the fourth invention, the control signal from the display control unit to the column line driver includes a switching control signal for controlling a switching operation of the switch. It is preferable that the switching control signal is configured to make the selection time of the data signal longer than the selection time of the black display signal.

  According to the above configuration, the supply time of the data signal is longer than the supply time of the black display signal. Therefore, it is possible to cope with a case where the display panel has a high pixel density and a large number of row lines, so that sufficient data signal supply time cannot be obtained.

  Further, in the liquid crystal display device according to the third invention or the fourth invention, the control signal from the display control unit to the column line driver includes a switching control signal for controlling a switching operation of the switch. It is preferable that the switching control signal is set so that the selection time of the data signal is equal to the selection time of the black display signal.

  According to the above configuration, since the supply time of the data signal is equal to the supply time of the black display signal, the supply of the data signal and the supply of the black display signal can be switched by a very simple switching control process. .

  Further, in the liquid crystal display device according to the fourth invention, the control signal from the display control unit to the row line driver is for identifying whether or not the control signal is a black display signal supply period for supplying the black display signal. The row line driver includes an identification signal, and supplies the selection signal to the (n + m) -th to (n + m + k-1) -th row lines during the black display signal supply period based on the identification signal. It is desirable that it is.

  According to the above configuration, the black display signal is supplied to all the picture elements k times during the predetermined time corresponding to m until the next data signal is applied. Therefore, even when the black display signal supply time according to the above m is insufficient for performing the black image display, the black display is reliably performed by repeating the black display signal supply k times. Thus, even when the pixel density of the display panel is high and the number of lines is large, and the black display signal supply time is not sufficient, high-quality moving image display with no backlight leakage is performed. .

  Further, in the liquid crystal display device invention according to the fourth invention, the control signal from the display control unit to the row line driver includes a scan start signal, the row line driver includes a shift register having a plurality of latch circuits, Based on the identification signal, the scan start signal is supplied to the first latch circuit of the shift register during the data signal supply period, while the scan start signal is supplied to the mth shift circuit during the black display signal supply period. It is desirable to have a scanning start signal supply means for supplying from the latch circuit to k consecutive latch circuits.

  According to the above configuration, a row line driver capable of supplying a black display signal k times before a data signal is applied next is realized with a simple configuration in which a scanning start signal supply unit is provided in a row line driver having a shift register. You.

  Further, in the liquid crystal display device according to the fourth aspect of the invention, it is preferable that the scanning start signal supply means is configured to be able to change a latch circuit number m and a latch circuit number k during the black display signal supply period.

According to the above configuration, by changing the latch circuit number m, the time for displaying the black image is changed before the next data signal is applied.
Further, by changing the number k of latch circuits, the number of times the black display signal is supplied until the next data signal is applied is changed.

  Further, the liquid crystal display device according to the fourth aspect of the present invention includes a supply control means for controlling an operation of the scan start signal supply means, and the supply control means controls the operation based on a scan start position designation signal from outside. It is desirable to output a control signal for setting the latch circuit number m to the scanning start signal supply means.

  According to the above configuration, the time for displaying the black image is changed before the next data signal is applied, based on an external signal.

  Also, in the liquid crystal display device according to the third or fourth aspect, the display control unit may perform a first operation of supplying a black display signal based on an operation of the changeover switch in response to an external command signal. It is preferable that a control signal for the display mode and a control signal for the second display mode in which the operation of the switch is stopped and the supply operation of the black display signal is not performed be switched and output.

  According to the above configuration, the display mode includes a first display mode in which energy consumption increases to supply a black display signal to the column line based on an operation of the changeover switch for each frame, and a normal display mode in which energy consumption is low. Is switched to the second display mode, and the waste of energy due to the display mode always being fixed to the first mode is prevented.

  Further, the liquid crystal display device according to the third or fourth aspect of the present invention includes a signal reference power supply for setting a voltage of a data signal supplied from the column driver, and a voltage of the signal reference power supply. Is desirably switchable between the first display mode and the second display mode.

  According to the above configuration, a black display signal is supplied after the data signal is written, and the transmittance of the liquid crystal is reduced to display a black image before a new image data signal is written in the next frame. In the first display mode, the voltage of the signal reference power source is switched, and the voltage of the data signal is set according to the decrease in the transmittance of the liquid crystal. Thus, a constant gradation balance is maintained between the first display mode and the second display mode.

  The liquid crystal display device according to the third or fourth invention monitors data relating to the same position on a screen based on a video signal from the display control unit, and an image based on the video signal is a moving image. It is desirable to include a moving image / still image discriminating unit that discriminates whether the image is a still image or a still image and outputs the command signal representing the result of the determination to the display control unit.

According to the above configuration, the moving image / still image determining unit determines whether the image is a moving image or a still image based on the video signal, and outputs a command signal indicating a result of the determination to the display control unit.
In this way, when displaying a moving image in which the display quality is likely to deteriorate, the control signal for the first display mode is automatically output from the display control unit, and after the data signal is written in one frame period, the data is transferred to the next frame. A black image is displayed before the signal is applied, and the display quality is improved.

  The liquid crystal display device according to the third or fourth aspect of the present invention may further include a backlight that irradiates the display panel from the back side, and the first display mode and the second display mode based on the command signal. It is desirable to have backlight dimming means for switching the brightness of the backlight.

  According to the above configuration, in the first display mode in which the transmittance of the liquid crystal is reduced in order to display a black image until the data signal is applied to the next frame after the data signal is written in one frame period. The backlight dimming means increases the brightness of the backlight, and in the case of the normal second display mode, the brightness of the backlight is reduced. Thus, waste of energy due to constantly increasing the brightness of the backlight is prevented.

  In the liquid crystal display device according to the third invention or the fourth invention, the black display signal generating means is constituted by a power supply for a black display signal, and the voltage of the power supply for the black display signal is set to be the same as that in the first display mode. It is desirable to be able to switch between the second display mode and the second display mode.

  According to the above configuration, in the first display mode in which a black image is displayed until a data signal is applied to the next frame after a data signal is written in one frame period, the power supply for the black display signal is used. The voltage is switched so that black display is reliably performed.

  As is apparent from the above description, the liquid crystal display method of the first invention supplies a selection signal to the n-th row line and supplies a data signal to the column line so that the picture element of the selected row line is based on the data signal. Displaying an image, and then supplying the selection signal to the (n + m) -th row line and supplying a black display signal to the column line to display a black image on the picture element of the selected row line; Since the image display operation and the black image display operation based on the data signal are repeated while sequentially shifting the lines, the data signal is written to all picture elements, and a predetermined time according to m elapses. After that, a black display signal is supplied, and the state in which the black display signal is written is maintained until a new image data signal is written in the next frame, so that a black image can be displayed. Therefore, when a picture element performing white display is changed to black display in the next frame, a black image is already displayed before the next data signal is written, thereby preventing leakage of light from the backlight. it can.

  Further, as described above, the picture element displaying the video turns black and the video disappears by the time the next data signal is applied, so that the edge of the video in the moving image is located ahead of the human gaze. And the subsequent period can be shortened. Therefore, blurring of the edge of the image can be reduced.

  That is, according to the present invention, the moving image display quality can be improved by the minimum change of supplying the black display signal to the column line and changing the method of selecting the row line.

  In the liquid crystal display method according to the second invention, a selection signal is supplied to an n-th row line and a data signal is supplied to a column line to display an image based on the data signal on a picture element of the selected row line. Next, the selection signal is simultaneously supplied to a plurality of row lines different from the n-th row, and a black display signal is supplied to the column lines to display a black image on the picture element of the selected row line. The display operation of the image based on the data signal and the display operation of the black image are repeated while sequentially shifting the data signals, so that the black display signal can be supplied a plurality of times before the next data signal is applied. Therefore, even when the black display signal supply time is insufficient for black image display, black display can be reliably performed by repeatedly supplying the black display signal a plurality of times.

  Therefore, according to the present invention, since the pixel density of the display panel is high and the number of rows is large, even when the black display signal supply time cannot be sufficiently obtained, light leakage from the backlight or image edge portions may occur. A high-quality moving image display that does not cause light bleeding can be performed with minimal changes.

  Further, in the liquid crystal display method according to the second aspect of the present invention, if the plurality of row lines are (n + α · m) (α = 1, 2,..., P) th row lines, Black display can be repeatedly performed every m scans. Therefore, it is possible to eliminate the fluctuation of the dielectric constant of the picture element capacitance due to the display contents in the immediately preceding frame, and to perform higher-quality display.

  Further, in the liquid crystal display method according to the second aspect, the plurality of row lines may be defined as (n + α · m) th row to (n + α · m + k−1) (α = 1, 2,..., P) th row line. In this case, black display can be performed by repeating k times with respect to a certain horizontal line every m scans. Therefore, the influence of the display content in the immediately preceding frame can be further eliminated.

  In the liquid crystal display method according to the first or second aspect of the present invention, when the supply time of the data signal is made equal to the supply time of the black display signal, the data signal can be very easily switched by the switching control processing. And the black display signal can be switched.

  In the liquid crystal display method according to the first invention or the second invention, if the supply time of the data signal is longer than the supply time of the black display signal, the pixel density of the display panel is high. It is possible to cope with a case where the data signal supply time cannot be sufficiently obtained due to a large number of row lines.

In the liquid crystal display method according to the first or second aspect of the invention, if the value of m is set so as to satisfy the following relationship, the supply time of the black display signal in one frame period is reduced to the white display time. Can be set to be equal to or longer than the response time of the liquid crystal when switching to black display. Therefore, even for a picture element for which a white image is displayed based on the data signal, black display can be reliably performed until the next data signal is applied.
fxm / N> t
Here, N: number of lines f: one frame time t: response time of the liquid crystal when switching from white display to black display

In the liquid crystal display method according to the first invention or the second invention, when the value of k is set so as to satisfy the following relationship, the supply time of the black display signal in one frame period is reduced to the black display time. It can be set to the minimum time or more in which white display can be switched to black display by supplying the signal k times. Therefore, when the supply of the black display signal is repeated k times because the supply time of the black display signal is insufficient, even if the picture element displays a white image based on the data signal, The black display can be reliably performed until the data signal is applied to the pixel.
T × k ≧ T ₀
Here, T: one supply time of the black display signal T ₀ : the shortest time of the black display signal which can completely switch the white display to the black display

In the liquid crystal display method according to the first or second invention, the voltage Vd when the data signal is a data signal for black display and the voltage Vr of the black display signal satisfy the following relationship. With such a setting, even when the black display signal is not supplied sufficiently and black display cannot be performed sufficiently, black display can be reliably performed.
In the case of positive polarity with respect to the potential level of the counter electrode, Vd <Vr in normally white, and Vd> Vr in normally black.
In the case of a negative polarity with respect to the potential level of the counter electrode, Vd> Vr in normally white and Vd <Vr in normally black.

  In the liquid crystal display device according to the third aspect of the present invention, when the data line is selected by the column line driver changeover switch according to the control signal from the display control unit, the row line driver selects the nth line line. While the signal is supplied, when the changeover switch selects the black display signal, the row line driver supplies the selection signal to the (n + m) th row line. Write a data signal, further supply a black display signal after a predetermined time according to m has elapsed, and hold the state where the black display signal is written until a new image data signal is written in the next frame. , Can display a black image. Therefore, when a picture element performing white display is changed to black display in the next frame, a black image is already displayed before the next data signal is written, and leakage of light from the backlight is reduced. Can be prevented.

  That is, according to the present invention, the moving image display quality can be improved by a minimum change in which a changeover switch is provided in the column line driver to change the control signal from the display control unit.

  Further, in the liquid crystal display device according to the fourth aspect of the invention, the row line driver selects the n-th row line when the data line is selected by the control signal from the display control unit. On the other hand, when the changeover switch is selecting the black display signal, the row line driver supplies the selection signal to a plurality of row lines different from the nth line. Even when the supply time is such that a single black display signal supply cannot provide a sufficient black image display, the black display can be reliably performed by repeating the black display signal supply a plurality of times. Therefore, even when the pixel density of the display panel is high and the number of row lines is large and the black display signal supply time is not sufficient, high-quality moving image display without backlight leakage can be performed. is there.

  In the liquid crystal display device according to the third or fourth invention, the row line is divided into L blocks every m lines, and the row line driver supplies a selection signal to the row line of each block. In the case where a data signal is supplied to a column line by the changeover switch, an n-th row line in a certain partial row line driver is selected, and a black display signal is transmitted to a column line. , The selection operation of the (n + m) row lines is performed by a simple control of selecting the n-th row line in the partial row line driver located in the rear column of the partial row line driver. Can be.

  Further, in the liquid crystal display device according to the third invention or the fourth invention, the switching control signal of the changeover switch, which is one of the control signals from the display control unit to the column line driver, is selected by the data signal. If the time is set to be longer than the selection time of the black display signal, the supply time of the data signal can be made longer than the supply time of the black display signal. Therefore, it is possible to cope with a case where the display element has a high pixel density and a large number of row lines, so that a sufficient data signal supply time cannot be obtained.

  Further, in the liquid crystal display device according to the third invention or the fourth invention, the switching control signal of the changeover switch, which is one of the control signals from the display control unit to the column line driver, is selected by the data signal. If the time and the selection time of the black display signal are set to be equal, the supply time of the data signal and the supply time of the black display signal can be made equal. Therefore, the supply of the data signal and the supply of the black display signal can be switched by a very simple switching control process.

  In the liquid crystal display device according to the fourth aspect of the present invention, the row line driver controls the black display signal supply period during the black display signal supply period based on an identification signal which is one of control signals from the display control unit to the row line driver. If the selection signal is supplied to the (n + m) th to (n + m + k-1) th row lines, the black display signal can be supplied k times before the next data signal is applied. Therefore, even when the black display signal supply time is insufficient, black display can be reliably performed. Therefore, according to the present invention, since the display panel has a high pixel density and a large number of row lines, even when the black display signal supply time cannot be sufficiently obtained, the backlight does not leak light and has high quality. Video display can be performed.

  In the liquid crystal display device according to the fourth aspect, the row line driver supplies a scan start signal as one of the control signals to a first latch circuit of a shift register during a data signal supply period. In the black display signal supply period, a scan start signal supply means for supplying the scan start signal from the m-th latch circuit of the shift register to the k successive latch circuits is provided. With a simple change that the line driver is provided with the scanning start signal supply means, it is possible to realize a row line driver that can supply a black display signal k times before the next data signal is applied.

  Further, in the liquid crystal display device according to the fourth aspect of the invention, if the scan start signal supply means is configured to be able to change the number of latch circuits m and the number of latch circuits k in the black display signal supply period, By changing m, the display time of the black image until the next data signal is applied can be changed. Further, by changing the number k of latch circuits, the number of times the black display signal is supplied until the next data signal is applied can be changed. Therefore, according to the present invention, it is possible to easily cope with a change in the pixel density of the display panel and a change in the environmental temperature.

  In the liquid crystal display device according to the fourth aspect of the invention, the supply control means outputs a control signal for setting the latch circuit number m to the scan start signal supply means based on an external scan start position designation signal. For example, the display time of a black image until the next data signal is applied can be changed based on an external signal.

  In the liquid crystal display device according to the third or fourth invention, the display control unit may control the first display mode control signal for supplying the black display signal in response to an external command signal. And the control signal for the second display mode in which the supply operation of the black display signal is not performed is switched, so that the display mode is always fixed to the first mode which consumes much energy. Energy can be prevented.

  Further, in the liquid crystal display device according to the third or fourth aspect, the voltage of the signal reference power supply for setting the voltage of the data signal supplied from the column line driver is changed between the first display mode and the second display mode. If it is possible to switch between the display modes, the voltage of the data signal can be set according to the decrease in the transmittance of the liquid crystal in the first display mode in which the transmittance of the liquid crystal is reduced. Therefore, it is possible to maintain a constant gradation balance between the first display mode and the second display mode.

  In the liquid crystal display device according to the third or fourth invention, the moving image / still image determining means determines whether the image is a moving image or a still image, and sends the command signal indicating the determination result to the display control unit. By outputting the control signal, a control signal for the first display mode is automatically output from the display control unit at the time of displaying a moving image in which the display quality is likely to deteriorate, and the data signal is then output to all the picture elements. A black image can be displayed before is applied. Therefore, the display quality can be improved by automatically detecting that the display image has changed to a moving image.

  Further, in the liquid crystal display device according to the third or fourth invention, the backlight dimming means switches the brightness of the backlight between the first display mode and the second display mode based on the command signal. Accordingly, the brightness of the backlight can be increased in the first display mode in which the transmittance of the liquid crystal is low. Therefore, waste of energy in the second display mode can be prevented as compared with the case where the brightness of the backlight is fixed in accordance with the first display mode.

  In the liquid crystal display device according to the third or fourth invention, the voltage of the black display signal power source as the black display signal generating means is switched between the first display mode and the second display mode. By doing so, it is possible to maintain a constant gradation balance between the first display mode and the second display mode.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

<First embodiment>
FIG. 1 is a schematic configuration diagram of an active matrix liquid crystal display device as a liquid crystal display device according to the present embodiment. The liquid crystal display device according to the present embodiment has a liquid crystal panel 11, a plurality of source drivers 12, and a plurality of gate drivers 13. The liquid crystal panel 11 has a TFT substrate 14 and a counter substrate 15. On the TFT substrate 14, there are provided pixel electrodes 16 arranged in a matrix and a TFT 17 having a drain connected to the pixel electrodes 16. A gate line G commonly connected to the gate of the TFT 17 in each row and arranged in parallel, and a source line S commonly connected to the source of the TFT 17 in each column and arranged in parallel are formed. Further, on a counter substrate 15 facing the TFT substrate 14 at a predetermined interval, a counter electrode 18 facing the picture element electrode 16 is formed. Although not shown, liquid crystal is interposed between the pixel electrode 16 and the counter electrode 18.

  Here, the liquid crystal panel 11 in the present embodiment has a VGA (video graphics array) in which the number of the gate lines G is 480 and the number of the source lines S is 640 (3 times in the case of color display). Panels are used. The 480 gate lines G are divided into three groups of 160 lines, and are connected to the first gate driver 13a to the third gate driver 13c for each group. Similarly, the source line S is divided into a plurality of groups and connected to the source driver 12 for each group.

  The display control unit 20 includes a clock signal generation unit, and outputs the generated clock signal to the first source driver 12 together with the input video signal. Further, it has a scanning start signal generation means and an identification signal generation means, and outputs the generated scanning start signal and the identification signal to each gate driver 13 together with a clock signal. The moving image / still image discriminating circuit 21 monitors several points of data on the screen based on the video signal received from the display control unit 20 to determine whether the image is a moving image mainly or a still image mainly. I do. Then, the determination result is returned to the display control unit 20. Then, the display control unit 20 switches one of the clock signals, the switching clock signal, the identification signal, and the scanning start signal, to one of a moving image and a still image based on the determination result.

  Further, the determination result from the moving image / still image determination circuit 21 is also output to a signal reference power supply 22, a black signal power supply 24, and a backlight dimming circuit 23. Then, the signal reference power supply 22 and the black signal power supply 24 send the data signal reference voltage and the black signal voltage according to the determination result to each source driver 12. The backlight dimming circuit 23 dims a backlight (not shown) according to the result of the determination. The black signal power supply 24 is a power supply used when generating a reset signal (black signal) described later in detail.

  FIG. 2 is a schematic configuration diagram of the source driver 12. However, the configuration relating to one source line S is shown as a representative, and all the source lines S have the same configuration. Data of one picture element (one horizontal line) is sampled from the video signal by the sampling memory 31, and the sampled data is stored in the holding memory 32. Then, the signal is subjected to DA conversion by the DA converter 33 using the signal reference voltage from the signal reference power supply 22, and transmitted to the changeover switch 34.

  The changeover switch 34 is a clock signal obtained by dividing the sampling clock signal supplied to the sampling memory 31, the holding memory 32, and the DA converter 33, and is the sampling memory 31, 31 of all the source drivers 12, 12,. ,... Are input with the switching clock signal having a period of time during which data of one horizontal line is sampled. When the level of the switching clock signal is, for example, “H”, the changeover switch 34 selects the data signal from the DA converter 33 and outputs it to the corresponding source line S. On the other hand, in the case of "L", the black signal voltage from the black signal power supply 24 is selected and output to the corresponding source line S as the reset signal.

  Note that the source driver 12 may be configured as shown in FIG. That is, in the source driver 12 shown in FIG. 2, the changeover switch 34 is located after the DA converter 33, but in FIG. 3, the changeover switch 35 is located before the holding memory 38. When the level of the switching clock signal is, for example, “H”, the changeover switch 35 selects the video signal from the sampling memory 37 and sends it to the holding memory 38. On the other hand, in the case of “L”, the black signal data from the black signal data generator 36 is selected and sent to the holding memory 38. Then, the digital signal is DA-converted by the DA converter 38 using the signal reference voltage from the signal reference power supply 22 and output to the corresponding source line S. Thus, the data signal based on the video signal is output to the source line S in the first half of the time when the data for one horizontal line is sampled, while the reset signal based on the black signal data is output in the second half. Is output to

  FIG. 4 is a schematic configuration diagram of the gate driver 13. However, the configuration of the gate driver 13 in the present invention is not limited to this. The gate driver 13 of the present embodiment has a shift register 41, and an output signal from each latch circuit (not shown) constituting the shift register 41 is supplied to an output circuit 42. Then, the output circuit 42 applies a gate voltage of the level “H” or the level “L” to the gate line G, and the gate line G is selected.

  The shift register 41 sequentially shifts the scan start signal supplied to the first latch circuit to the next latch circuit based on the clock signal from the display control unit 20, and sequentially selects the gate line G. go. In this case, the scanning start signal is also input to the analog switch 43 that opens and closes the identification signal from the display control unit 20 as a control signal, and the level of the identification signal becomes, for example, “H” and the analog switch 43 By opening, the scan start signal is also supplied to the second to fourth latch circuits in the shift register 41.

The liquid crystal display device having the above configuration operates as follows to display a moving image.
That is, FIG. 5 is a timing chart of the drive signals for the three gate drivers 13a, 13b, 13c and the selection signal output to each gate line G. As can be seen from FIG. 5, a clock signal delayed by a half cycle from the clock signal supplied to the first gate driver 13a located at one end is supplied from the display control unit 20 to the second gate driver 13b located at the center. Is done. Further, a clock signal delayed by a half cycle from the clock signal supplied to the second gate driver 13b is supplied to the third gate driver 13c located at the other end. The scanning start signal supplied from the display control unit 20 to each of the gate drivers 13a to 13c is a pulse signal having one pulse at the first clock and the 321st clock. They are input out of phase. Further, the identification signal supplied from the display control unit 20 to each of the gate drivers 13 a to 13 c has, for example, an “L” level for 320 clocks and an “H” level for 160 clocks. It is input with its phase shifted by 160 clocks.

As a result, first, the gate line G ₁ of the first by the first gate driver 13a is selected. After these, the first to fourth th gate line G by the second gate driver 13b, that is, as a whole 161-th to 164-th gate line G ₁₆₁ ~G ₁₆₄ is selected. Then, after the second gate line G ₂ is selected by the first gate driver 13a, gate lines G ₁₆₂ ~G ₁₆₅ of 162 th to 165 th by the second gate driver 13b (to 5 th second) is selected Is done. Thereafter, selection is sequentially performed by the two gate drivers 13a and 13b in the same manner, and the 320th (160th) gate line _G320 is selected by the second gate driver 13b.

Then, after the first gate line G, that is, the 161st gate line G ₁₆₁ as a whole is selected by the second gate driver 13b, the first to fourth gate lines G ₁₆₁ are selected by the third gate driver 13c. That is, the 321st to 324th gate drivers G _{321 to} G ₃₂₄ are selected as a whole. Then after the gate line G ₁₆₂ 162-th (second) is selected by the second gate driver 13b, the gate lines G ₃₂₂ ~G of 322 th to 325 th the third gate driver 13c (to 5 th second) ₃₂₅ is selected. Thereafter, selection is sequentially performed in the same manner by the two gate drivers 13b and 13c, and the 480th (160th) gate line G480 is selected by the third gate driver 13c.

Then, after the first gate line G, that is, the 321st gate line G ₁₆₁ as a whole is selected by the third gate driver 13c, the first to fourth gates are again formed by the first gate driver 13a. is the line G ₁ ~G ₄ is selected.
After the gate line G ₄₈₀ 480-th through third gate driver 13c (160 th) is selected, the 160-th gate line G ₁₆₀ by the first gate driver 13a is selected, one frame scanning is ended You do it.

  As described above, the timing chart shown in FIG. 5 is a case where the identification signals having the “H” level for 160 clocks are sequentially given to the gate drivers 13 b to 13 a, and the level of the identification signal is “H”. , The analog switch 43 of the gate driver 13 is turned on, and the gate driver 13 selects four consecutive gate lines G. On the other hand, when an identification signal whose level is all “L” is given to each gate driver 13, the analog switches 43 of all the gate drivers 13 are off, and therefore, as shown in FIG. The two gate drivers 13 select the gate lines G one by one alternately and while shifting.

  Hereinafter, an image display operation by the liquid crystal display device according to the present embodiment will be specifically described. As described above, the column of the source driver 12 alternately outputs the data signal stored in the holding memory 32 and the reset signal. In this case, the pulse width of the switching clock input to the changeover switch 34 is set so that the output time widths of both signals are equal to each other. The width of the output time in the present embodiment is about 16.7 ms (one frame time) / 480 lines / 2 ≒ about 17 μs.

Further, it is assumed that the clock signal and the scanning start signal as described above, and the identification signal whose level is all “L” are input to the gate driver 13 for selecting the horizontal line.
Then, as shown in FIG. 6, after the nth gate line G is selected, the (n + 160) th gate line G is selected. Further, after the (n + 1) th gate line G is selected, the (n + 161) th gate line G is selected. However, if (n + m) is larger than the number of lines, the selected line is obtained counting from the first line following the last line. The width of the selection time of each gate line G is about 17 μs, similarly to the width of the signal output time to the source line S. In this case, the source driver 12 selects the n-th gate line G when outputting the data signal, and the source driver 12 selects the (n + 160) -th gate line G when outputting the reset signal. The timing between the switching clock and the scanning start signal is set in advance.

As described above, the reason why the reset signal is applied to the gate line G (m = 160) 160 lines ahead of the gate line G that has output the data signal is as follows. That is, the response time when the transmittance of the liquid crystal changes from 100% to 10% is about 4 ms. When a reset signal is applied to a picture element electrode of a picture element connected to a certain gate line G, it is necessary that the display is substantially black by the time the next data signal is applied. Therefore, the following relationship is established.
fxm / N> 4ms
However, f: 1 frame time (16.7 ms)
N: Total number of gate lines (480 lines)
Therefore, it is necessary that m> 115.

  Here, in the present embodiment, three gate drivers 13 connected to 160 gate lines G are arranged in a straight line to scan 480 gate lines. Therefore, assuming that m = 160, the reset signal from the gate driver 13 following the gate driver 13 which is currently outputting the data signal to the gate line G having the same number as the gate line G to which the data signal is being output. Is output, the condition of m> 115 can be cleared.

  The display result by such an image display operation is as follows when compared with the display result by the conventional liquid crystal display device. Here, in the image used for the description, as shown in FIG. 7, a white band 52 having a width of three picture elements is arranged in the center of a black background 51 in the vertical direction. It is assumed that the white band 52 is a moving image that moves by one picture element per frame as indicated by the arrow (A).

  First, an image display method using a conventional liquid crystal display device will be described. FIG. 8 shows an image display sequence in one frame period by the conventional liquid crystal display device. One horizontal line of the video signal sent one after another is sampled by the sampling memory 2 of the source driver 1 and temporarily stored in the holding memory 3. Then, a data signal for one horizontal line read from the holding memory 3 is written to a picture element row constituting one horizontal line selected by the gate driver. At the same time, the data signal of the second horizontal line is sampled by the sampling memory 2 and the contents of the holding memory 3 are rewritten. This is repeated for 480 horizontal lines, and the data signal writing for one frame is completed.

  The liquid crystal employs a normally white type TN (twisted nematic) mode. In addition, the characteristic is that the time for the transmittance to go from 0% to 90% is about 20 ms, and the time for the transmittance to go from 100% to 10% is about 4 ms.

  When the moving image as described above is displayed by an image display sequence of a conventional liquid crystal display device, as shown in FIG. Bleeding) is seen. This cause is explained as follows. That is, FIG. 10 shows the transmittance change for each frame in an arbitrary picture element 54 adjacent to the white band 52 in the forward direction of the white band 52 in FIG. This change in transmittance is ideally a black display (transmittance <10%) in the first frame, a white display (transmittance> 90%) in the second to fourth frames, and a fifth frame. Then it should return to black display again. However, as described above, the liquid crystal has the characteristics that the time required for the transmittance to reach 0% to 90% is about 20 ms, and the time required for the transmittance to reach 100% to 10% is about 4 ms. For this reason, when a white signal is written in the second frame to the picture element 54 that was displayed in black in the first frame, the liquid crystal of the picture element 54 could not complete the response within the frame time and was almost completed in the third frame. Will do. Therefore, the original white display is performed in the fourth frame. Then, in the fifth frame, a black signal is written, but since the time for the transmittance to reach 100% to 10% is about 4 ms, slight light leakage is observed as shown by the picture element row 53. It is. Therefore, in the conventional image display sequence, the width of the white band 52 is not clearly seen for three picture elements.

  Next, an image display operation in the liquid crystal display device of the present embodiment will be described. In the present liquid crystal display device, a reset signal of a voltage capable of achieving black display within one frame period is written between data signal writing of each horizontal line. FIG. 11 shows an image display sequence in the liquid crystal display device of the present embodiment. FIG. 11B shows the specific contents of the write and reset periods in FIG. 11A. As shown in FIG. 11, in the present embodiment, the writing of the data signal and the writing of the reset signal are alternately performed in a half cycle of the sampling cycle. In that case, the reset signal is written to the horizontal line 160 lines ahead of the data signal write horizontal line.

  In the present embodiment, by employing such an image display sequence, as shown in FIG. 12, no afterimage (bleeding of an image) is confirmed in the picture element sequence 63 changed from the white band 62 to the background 61. . The reason can be explained as follows. FIG. 13 shows the transmittance change of each frame in an arbitrary picture element 64 (corresponding to the picture element 54 in FIG. 7) adjacent to the white band 62 in the forward direction of the white band 62 in FIG. This picture element 64 is displayed in black in the first frame. Then, a white signal is written in the second frame, but at a certain point in the frame time (the next point when the white signal is written to a horizontal line 160 lines behind the horizontal line to which the picture element 64 belongs). At a, a black signal is written. The voltage of the black signal is a voltage capable of achieving black display within one frame period as described above, and the time point a is set so that the transmittance reaches 10% within the remaining time of the second frame. is there. Therefore, it is possible to return to the black display by the next frame.

  This is the same in the third and fourth frames. Therefore, in the second to fourth frames, a white signal is written to the picture element 64 for the same time, and the maximum transmittance in each frame becomes the same. As a result, the display with the same luminance can be performed in the second to fourth frames. Further, in the fifth frame, since the black signal has already been written after the time point a of the fourth frame, the transmittance at the start time is 10% or less, and no light leakage is observed.

  Further, the reduction of the afterimage by the image display sequence according to the present embodiment can also be explained for the following reasons. In order to simplify the description, a case where the response time of the liquid crystal is infinitely small will be described. The image used in the description is a moving image in which the white band having a width of three pixels moves in one direction by one pixel per frame as described above, and FIG. 14 shows the movement of the white band in an arbitrary horizontal line. Show the situation. FIG. 15 shows the response waveform of the transmittance at the infinitesimal response time in the case of the conventional image display sequence, and FIG. 16 shows the case of the image display sequence of the present embodiment.

  FIG. 17 shows how a white band moves on an arbitrary horizontal line according to a conventional image display sequence. Since the data signal written to an arbitrary picture element is held during the frame period, the white band is stopped during one frame period. Then, in the next frame period, it moves by one picture element and stops again for one frame period. Thereafter, the above is repeated. Then, when a human observes the movement of the above-mentioned white band, it is recognized as a moving image in which the white band moves smoothly. In other words, it is not possible to recognize that the white band is stationary for each frame. Therefore, as shown by broken arrows (B) and (C) in FIG. 17, the human viewpoint moves at a constant speed.

  Therefore, in the human retina, as shown in FIG. 18, the luminance in consideration of the movement is felt. As a result, both edges appear to be duller than the actual white band image based on the data signal, and a blurred afterimage is felt. In other words, the human eye feels that the white band is moving smoothly in each frame, even though the white band is stationary, so that the white band is indicated by the symbol “b” in the first half of one frame. Since the line of sight is ahead of the line of sight of the human and the line of sight of the human overtakes the white band in the latter half of one frame, there is a white band after the line of sight as indicated by the symbol “c”. Then, since an image in which the presence / absence of the white band image is averaged is projected on the human retina, a white band image with dull edges and blurred is seen. As described above, in the conventional image display sequence, blurring of a moving image is always felt.

  Next, a case of an image display sequence in the liquid crystal display device of the present embodiment will be described. FIG. 19 shows how white bands move on an arbitrary horizontal line according to the image display sequence of the present embodiment. In this image display sequence, the difference "m" between the write line number of the reset signal and the write line number of the data signal is set to "160". Are held, and in the latter half, a black signal is held and black display is performed. That is, the white band is stopped in the first half of the one-frame period and disappears in the second half. Therefore, the display period of the white band can be shortened to 2/3 of one frame period. As is clear from the comparison between FIG. 19 and FIG. 17, the white band indicated by the symbol “b” is positioned ahead of the human line of sight. It is possible to shorten the time period and the time period after the line of sight indicated by the symbol “c”. As a result, as shown in FIG. 20, the bleeding of the edge of the white band image can be reduced.

  In the above description, for the sake of simplicity, it is assumed that the response time of the liquid crystal is infinitely small, but if black display is performed for each frame, the same effect can be obtained even if the response time of the liquid crystal is not infinitely small. It is clear from the above description.

  By the way, as can be seen from the comparison between FIG. 15 and FIG. 16, in the present embodiment, the process of changing the black transmittance to an arbitrary transmittance and the arbitrary transmittance to the black Since the process includes a process of transmissivity, the transmissivity is substantially lower than when the conventional image display sequence is applied. Therefore, it is necessary to increase the brightness of the backlight in order to obtain the same brightness as when the conventional image display sequence is applied.

  Therefore, considering the adoption of this liquid crystal display device in portable equipment, several points on the screen are monitored, and it is automatically determined whether the currently displayed image is a moving image-based image or a still image-based image. A moving picture / still picture discriminating circuit 21 for discriminating is provided. When the backlight dimming circuit 23 determines that the image is a moving image in accordance with the determination result of the moving image / still image determining circuit 21, the brightness of the backlight is increased. When it is determined that the image is a still image, the brightness of the backlight is reduced. By doing so, power consumption can be reduced as compared with the case where the backlight brightness is always fixed to the moving image, and a portable liquid crystal display device with excellent moving image display quality can be minimized. It can be obtained with minimal power consumption.

  Note that, instead of providing the moving image / still image discriminating circuit 21, a switch for selecting the image display sequence of the present embodiment or the conventional image display sequence is provided so that the user can select any one of the image display sequences. No problem. Then, when the switch is switched to the image display sequence side of the present embodiment, the backlight dimming circuit 23 synchronously increases the luminance of the backlight. Also in this case, a liquid crystal display device having excellent moving image display quality can be obtained with a minimum increase in power consumption.

  Further, as described above, in the present embodiment, since a process of changing the black transmittance to an arbitrary transmittance and a process of changing the arbitrary transmittance to the black transmittance are included in each frame, as shown in FIG. The relationship between the writing voltage and the transmittance is different from that in the conventional image display sequence. Further, as shown in FIG. 22, the temporal change of the transmittance at each gradation is different between the image display sequence of the present embodiment and the conventional image display sequence.

  Therefore, when the image display sequence according to the present embodiment is adopted in consideration of these results, the signal reference power supply 22 uses the signal reference power supply 22 based on the determination result of the moving image / still image determination circuit 21 to write the write voltage for each gradation. Is readjusted to a large value with reference to the black display, whereby a better gradation balance can be obtained as compared with the case where a conventional image display sequence is adopted.

  As described above, in the present embodiment, a VGA panel is used as the liquid crystal panel 11. The source driver 12 includes a changeover switch 34 for switching and outputting both the data signal stored in the holding memory 32 and the reset signal based on the black signal voltage to the source line S during one horizontal line sampling period. Provide. Also, 480 gate lines G are divided into three groups of 160 lines each, and the gate lines G of each group are connected to the first gate driver 13a to the third gate driver 13c.

  Then, the display control unit 20 supplies the first gate driver 13a to the third gate driver 13c with clock signals whose phases are sequentially delayed by a half cycle. Further, a scan start signal having one pulse at the first clock and the 321st clock is input from the display control unit 20 to the first gate driver 13a to the third gate driver 13c with a phase shifted by 160 clocks. ing.

  Therefore, when the source driver 12 outputs the data signal, the gate driver 13 selects the nth gate line G, and when the source driver 12 outputs the reset signal, the (n + 160) th gate line is selected. By setting the timing of the switching clock and the scan start signal so as to select G, as shown in FIG. Is written with a reset signal.

  At this time, if the voltage of the reset signal (that is, the voltage of the black signal power supply 24) is set to a voltage that can achieve black display within one frame period, it is possible to return to black display by the next frame. it can. That is, according to the present embodiment, when a black signal is written in the next frame for a picture element in which a white signal has been written, the black signal has already been written in the latter half of the previous frame. At the start of the frame, the transmittance is 10% or less, and no light leakage is observed.

  Further, the edge portion of the video in the moving image repeatedly moves and stops in each frame. In this case, since the stop of the edge portion cannot be visually recognized by a human, the edge portion appears to be moving smoothly. In the present embodiment, a reset (black) signal is written to the picture element to which the data signal is written in the latter half of the frame, so that the picture disappears. However, since the human cannot visually recognize that the image has disappeared, the period in which the edge portion of the image is ahead of and behind the line of sight of the human is shortened. As a result, as shown in FIG. Of the edge portion can be reduced.

  Further, in the present embodiment, a moving image / still image discriminating circuit 21 for automatically judging whether a displayed image is an image mainly composed of a moving image or an image mainly composed of a still image is provided. When the moving image / still image discriminating circuit 21 determines that the image is a moving image, the backlight dimming circuit 23 increases the luminance of the backlight. Therefore, at the time of displaying a moving image, it is possible to prevent a decrease in transmittance caused by writing a reset signal one-third after one frame with a minimum necessary increase in power consumption.

  That is, according to the present embodiment, it is possible to improve the moving image display quality with the minimum necessary power consumption increase by performing the minimum improvement on the liquid crystal display device having the conventional VGA panel. is there.

  Although the above description of the operation has been made by taking the case of displaying a moving image as an example, it goes without saying that a still image can also be displayed. When a still image is displayed, the display control unit 20 outputs a still image switching clock signal having all levels “H” to the source driver 12 so that only the data signal is output over the entire sampling period of one horizontal line. Is output. Further, a scanning start signal for a still image including one pulse is input to each of the gate drivers 13a to 13c with a phase shift of 160 clocks, while an identification signal for a still image having a level of "L" is input to each of the gate drivers. 13 is output. Thus, similarly to the conventional liquid crystal display device, an image is displayed by outputting data signals to all the source lines S while sequentially selecting 480 gate lines G from one end.

  In the above description, the relationship between the voltage of the signal reference power supply 22 and the voltage of the black signal power supply 24 is not particularly described, but the display quality can be further improved by setting as follows. That is, assuming that the black image reference voltage (black reference voltage) from the signal reference power supply 22 is Vd and the voltage of the black signal power supply 24 is Vr, when the potential level of the counter electrode 18 is positive. Sets both voltages so as to satisfy the relationship of Vd <Vr in normally white and Vd> Vr in normally black. On the other hand, in the case of the negative polarity, both voltages are set so as to satisfy the relationship of Vd> Vr at the time of normally white and Vd <Vr at the time of normally black. By doing so, the shortage of the supply time of the black display signal can be compensated for, and the display quality can be further improved.

Normally, the TFT (switching element) 17 requires a supply time of at least 20.5 μs in order to reliably supply a signal voltage. On the other hand, as described above, when the VGA panel is driven at a frame time of 16.7 ms (= 16700 μs), that is, when 480 gate lines G are driven at 60 Hz, one horizontal period takes 10 to 10 hours. ⁶ μs / 60 (Hz) / 480 (lines) = 34.7 μs. Therefore, the data signal supply time and the black signal supply time are set as follows: data signal supply time = 20.8 μs, black signal supply time = 34.7 μs−20.8 μs = 13.9 μs. FIG. 23 shows a timing chart of each drive signal and selection signal, and FIG. 24 shows an image display sequence.

  By setting each signal supply time in this manner, data from the source drivers 13a to 13c can be reliably supplied to the pixel electrodes 16. If the black signal supply time is short, it is considered that a sufficient supply of the black signal (charging to the pixel capacitance) is not performed. However, in the case of many liquid crystal display elements, looking at the voltage-transmittance curve, the transmittance changes insensitively to the voltage in the vicinity of the black display (the transmittance is saturated to 0 near the black display. Therefore, a sufficient effect can be obtained even if the supply of the black signal is somewhat short. In the present embodiment, one frame time is defined as the time required to display an image on the entire screen of the liquid crystal display device regardless of the video signal system. For example, in the case of the interlaced video signal system, one frame time is generally composed of two fields, and the entire screen of the liquid crystal display device is displayed in one field time corresponding to a half of the frame time. In this case, the one field time is regarded as one frame time in the present embodiment. The same applies to other video signal systems. This is the same in each of the following embodiments.

<Second embodiment>
The schematic configuration of the liquid crystal display device according to the present embodiment is the same as the active matrix type liquid crystal display device according to the first embodiment shown in FIG. However, the liquid crystal display device according to the present embodiment uses an S-XGA (super XGA) panel for the liquid crystal display portion. The number of picture elements is 1280 (three times in the case of color display) × 1024, which is different from the VGA panel in the first embodiment by about twice the number of gate lines G. Therefore, as in the case of the first embodiment, if the data signal and the reset signal are alternately output with the same output time width, the selection time of one horizontal line is about 16.7 ms (one frame time) / 1024 lines / 2 ≒ about 8.1 μs. Therefore, it is not possible to sufficiently write (that is, charge) each signal to the picture element.

  In view of the ability of the TFT element to switch the connection between each pixel electrode and the source line S, the selection time for one horizontal line requires at least 12.0 μs. Therefore, in the present embodiment, the switching clock supplied to the selector switch 34 in the source driver 12 is 16.7 ms (one frame time) / 1024１０about 16.3 μs of the maximum selection time of one horizontal line. , 12.0 μs is assigned to the data signal writing time, and the remaining 4.3 μs is assigned to the reset signal writing time.

  However, in such a reset signal writing time, it is impossible to sufficiently write the reset signal in one selection period. Accordingly, in the present embodiment, as shown in FIGS. 25 and 26, 1024 gate lines G are divided into four groups of 256 lines, and four gate drivers (hereinafter, referred to as four gate drivers) different for each group. (Referred to as a first gate driver 13a to a fourth gate driver 13d). However, the basic configuration of each gate driver 13 is the same as the configuration shown in FIG. At the time of displaying an image, the display control unit 20 sends an identification signal indicating that an “L” level for 768 clocks and an “H” level for 256 clocks exist to each of the gate drivers 13 a to 13 d. It is input with a phase shifted by 256 clocks. In addition, a scan start signal having one pulse at the first clock and the 769 clock is input to each gate driver 13 with a phase shifted by 256 clocks.

  As a result, the analog switch 43 of the gate driver 13 in which the level of the identification signal is “H” is turned on, so that four consecutive gate lines G are selected in the gate driver 13 and are adjacent to each other. One gate line G and four gate lines G are alternately selected by the two gate drivers 13 while shifting.

  An image display sequence in the liquid crystal display device of the present embodiment is as shown in FIG. FIG. 27B shows the specific contents of the write and reset periods in FIG. As shown in FIG. 27, in the present embodiment, writing of a data signal and writing of a reset signal are alternately performed at different time widths as described above. In this case, the writing of the reset signal is performed simultaneously on four horizontal lines continuous from 256 data signal writing horizontal lines based on the identification signal and the scanning start signal from the display control unit 20 as described above. It is done.

  By doing so, it is possible to write the reset signal to each horizontal line four times in one frame continuously, and as shown in FIG. 28, black display is sufficiently performed even if the reset signal writing time is set to 4.3 μs. Can be made. That is, according to the present embodiment, in an active matrix liquid crystal display device using an S-XGA panel as the liquid crystal panel 11, bleeding and afterimage of moving image display can be reduced.

In the present embodiment, as described above, the reset signal is given to the gate line G (m = 256) 256 lines ahead of the gate line G that has output the data signal for the following reason. That is, as described above, the response time when the transmittance of the liquid crystal changes from 100% to 10% is about 4 ms. When a reset signal is applied to a picture element electrode of a picture element connected to a certain gate line G, it is necessary that the display is substantially black by the time the next data signal is applied. Therefore, the following relationship is established.
fxm / N> 4ms
However, f: 1 frame time (16.7 ms)
N: Total number of gate lines (1024)
Therefore, it is necessary that m> 246.

  Here, in the present embodiment, four gate drivers 13 connected to the 256 gate lines G are arranged in a straight line to scan 1024 lines. Therefore, if m = 256, a reset signal is sent from the gate driver 13 following the gate driver 13 which is currently outputting the data signal to the gate line G having the same number as the gate line G to which the data signal is being output. Is output, the condition of m> 246 can be cleared.

  Also in the case of the present embodiment, the moving image / still image discriminating circuit 21 automatically determines whether the displayed image is an image mainly composed of a moving image or an image mainly composed of a still image. If the luminance of the backlight is increased by the circuit 23, a portable liquid crystal display device having excellent moving image display quality can be obtained with a minimum necessary increase in power consumption.

  In the above description, an example is given in which a data signal is written to the n-th gate line G, and then a reset signal is written to the k gate lines G continuously from the (n + m) -th gate line. However, the K gate lines G to which the reset signal is written may be divided into p groups every m lines. In this case, the reset signal is simultaneously written to k (= K / p) consecutive k groups.

FIG. 29 shows an example of a timing chart of each drive signal and selection signal (the gate driver 13d is omitted). FIG. 30 shows an image display sequence for one frame period.
FIG. 29 is an example of the case where m = 256, p = 2, and k = 1.

  As described above, the following effects can be obtained by writing the reset signals to the gate lines G dispersedly in p groups every m lines. That is, the liquid crystal has a characteristic in which it starts responding to the black display by the start of the writing of the reset signal, and its dielectric constant changes gradually (due to the dielectric anisotropy of the liquid crystal). Therefore, even if a predetermined reset voltage is applied to the liquid crystal, the voltage actually applied to the liquid crystal varies due to a change in the dielectric constant.

  However, by supplying a reset signal to k gate lines G dispersedly in p groups every m lines, focusing on a certain horizontal line, the reset signal is output once every m lines are scanned. Will be supplied. That is, the liquid crystal responds to some extent by the first reset signal, and its dielectric constant changes. After the m-th scan, the second reset signal is supplied to the liquid crystal whose dielectric constant has changed. Therefore, by repeating this operation p times, more reliable black display can be obtained.

  In other words, the signal supply to the liquid crystal element is an operation of applying a signal voltage to each pixel capacitor (that is, a charging operation). Therefore, the dielectric constant of the liquid crystal changes depending on the display content (alignment state), and the charge amount differs depending on the previous display content. Therefore, even if the same signal is supplied to the same picture element, a different display will result if the previous display content is different.

  However, as described above, by repeatedly writing the reset signal p times with a time sufficient for the m gate lines G to be scanned, the above-described problem of the change in the dielectric constant can be improved, which is more favorable. A black display can be obtained.

<Third embodiment>
In the liquid crystal display device according to the first embodiment, when used at low temperatures, the response speed of the liquid crystal becomes slow. Therefore, the data signal of the next frame is written before the black display by the reset signal is completed. There is a problem that the amount of bleeding increases. This problem can be solved by applying the second embodiment, that is, by switching the identification signal from the display control unit 20. However, the transmission from the transmittance according to the data signal to the black transmittance becomes possible. The problem can also be solved by controlling the response time so that it falls within the frame period. Hereinafter, a method of controlling the response time from an arbitrary transmittance to a black transmittance according to the data signal will be described.

  As a method for controlling the response time, there is the following method.

  (1) “m”, which is the difference between the write line number of the reset signal and the write line number of the data signal, increases as the environmental temperature decreases. This makes it possible to extend the reset signal writing time so that the response time at the time of writing the reset signal falls sufficiently within the frame period, thereby compensating for a reduction in the response speed of the liquid crystal.

  (2) The black signal voltage (that is, the reset signal voltage) from the black signal power supply 24 is increased as the environmental temperature decreases. As a result, the reset signal writing speed can be increased so that the response time at the time of writing the reset signal can be sufficiently settled within the frame period, and the decrease in the response speed of the liquid crystal can be compensated.

  Although there are various methods for changing “m” in the above (1), for example, it is performed as follows. That is, the shift registers 41 of the gate drivers 13 divided into a plurality are connected in series. Then, an analog switch is connected to each of the input terminals of the m-th to (m + J) -th latch circuits among the latch circuits constituting the entire shift register 41, and the analog switches are connected via any of the (J + 1) analog switches. The scanning start signal can also be input to the input terminals of the m-th to (m + J) -th latch circuits. Further, a control circuit for the analog switch is provided, and this control circuit turns on the (m + j (j ≦ J))-th analog switch in response to a fall in the ambient temperature.

  In the present embodiment, even if only one of the control methods (1) and (2) is performed, it is possible to avoid an increase in the amount of bleeding of the moving image due to a decrease in the response speed of the liquid crystal.

  In the second embodiment, the case where the reset signal is written to four horizontal lines at the same time has been described as an example. However, the present invention is not limited to the four horizontal lines. . Furthermore, the writing of the reset signal is not limited to the fixed number of horizontal lines, and the number of reset signal writing may be changed. In this case, various methods of changing the number of reset signals to be written can be considered. For example, the following method may be used.

  That is, in FIG. 4, an analog switch is connected to each of the input terminals of the second to Kth latch circuits in each gate driver 13, and the analog switch 43 is connected via any of the (K-1) analog switches. Can be supplied also to the input terminals of the second to Kth latch circuits. Further, a control circuit for the analog switch is provided, and the control circuit turns on the second to k-th (k ≦ K) analog switches in response to a k signal from the outside. Note that the k signal is a signal that specifies the number of reset signals to be written.

  In each of the above embodiments, the case where the present invention is applied to an active matrix type liquid crystal display device is described as an example. However, it is needless to say that the present invention can also be applied to a duty type liquid crystal display device.

FIG. 1 is a diagram showing a schematic configuration of a liquid crystal display device of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of a source driver in FIG. 1. FIG. 3 is a diagram illustrating a schematic configuration of a source driver different from FIG. 2; FIG. 2 is a diagram illustrating a schematic configuration of a gate driver in FIG. 1. FIG. 5 is an explanatory diagram when the analog switch in FIG. 4 operates. 5 is a timing chart of drive signals of three gate drivers and a selection signal output to each gate line in the first embodiment. It is an explanatory view of an image used for explanation of a moving image display operation. FIG. 9 is a diagram showing a conventional image display sequence. FIG. 8 is an explanatory diagram of bleeding occurring in the image shown in FIG. 7. It is a figure which shows the transmittance | permeability change for every frame in the white belt picture element based on the conventional image display sequence. FIG. 2 is a diagram showing an image display sequence in the liquid crystal display device shown in FIG. FIG. 12 is a diagram illustrating a display result of the image illustrated in FIG. 7 based on the image display sequence illustrated in FIG. 11. FIG. 12 is a diagram illustrating a change in transmittance for each frame based on the image display sequence illustrated in FIG. 11. FIG. 8 is a diagram showing a state of movement of a white band on an arbitrary horizontal line of the image shown in FIG. 7. FIG. 9 is a diagram showing a response waveform of transmittance in a conventional image display sequence when the response time of the liquid crystal is set to infinity. FIG. 12 is a diagram showing a response waveform of transmittance in the image display sequence shown in FIG. 11 when the response time of the liquid crystal is set to infinity. FIG. 11 is a diagram illustrating movement of a white band and movement of a human viewpoint in a conventional image display sequence. FIG. 18 is a diagram illustrating a state in which the luminance of both edges of the white band is reduced due to a shift between the movement of the white band illustrated in FIG. 17 and the movement of the human viewpoint. FIG. 12 is a diagram showing movement of a white band and movement of a human viewpoint in the image display sequence shown in FIG. 11. FIG. 20 is a diagram illustrating a state in which the brightness of both edges of the white band is reduced due to a shift between the movement of the white band illustrated in FIG. 19 and the movement of the human viewpoint. FIG. 12 is a diagram illustrating a relationship between a writing voltage and a transmittance in the image display sequence illustrated in FIG. 11 and a conventional image display sequence. FIG. 12 is a diagram showing a temporal change in transmittance at each gradation in the image display sequence shown in FIG. 11 and a conventional image display sequence. 7 is a timing chart of a drive signal and a selection signal different from FIG. FIG. 12 is a diagram illustrating an image display sequence different from that in FIG. 11. 9 is a timing chart of a drive signal and a selection signal according to the second embodiment. It is a timing chart following FIG. FIG. 25 is a diagram illustrating an image display sequence different from those in FIGS. 11 and 24. FIG. 28 is a diagram illustrating a change in transmittance of each frame based on the image display sequence illustrated in FIG. 27. It is a timing chart different from FIG. FIG. 30 is a diagram showing the image display sequence of FIG. 29. FIG. 9 is a schematic configuration diagram of a source driver in a conventional liquid crystal display device.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 11 ... Liquid crystal panel 12 ... Source driver 13 ... Gate driver 20 ... Display control part 21 ... Moving image / still image discrimination circuit,
22: Reference power supply for signal 23: Backlight dimming circuit 24: Power supply for black signal 31, 37 ... Sampling memory 32, 38 ... Holding memory 33, 38 ... DA converter 34, 35 ... Changeover switch 36 ... Black signal data generator 41 shift register 42 output circuit 43 analog switch

Claims (27)

A plurality of column lines arranged in parallel with each other, a plurality of row lines arranged in parallel with each other intersecting the plurality of column lines, and an intersection of the plurality of column lines and the plurality of row lines. A method for displaying an image on a liquid crystal display device having a plurality of picture elements provided correspondingly,
(A) A selection signal is supplied to one of the row lines from the n-th row line to the (n + m-1) -th row line (n and m are positive integers), and the plurality of row lines are supplied. Supplying a data signal to each of the column lines to supply a predetermined data signal of a picture element corresponding to the one row line among the plurality of picture elements;
(B) Before or after the step (a), of the l-th (l is a positive integer, l ≧ n + m or l + m ≦ n) to l + m−1 of the plurality of row lines And a black display signal is supplied to each of the plurality of column lines so as to correspond to the at least one row line in the plurality of picture elements. Supplying a black display signal to the picture element to be processed,
The step of supplying the data signal to each of the plurality of column lines in the step (a) and the step of supplying the black display signal to each of the plurality of column lines in the step (b) comprise the steps of: It is executed by switching the black display signal and supplying one of them to the plurality of column lines,
By executing the steps (a) and (b) a plurality of times, the predetermined data signal and the black display signal are supplied in one frame period for each of the plurality of picture elements. A liquid crystal display method, wherein a state in which a black display signal is supplied is maintained for more than 4 / 16.7 of one frame period in each element.   The liquid crystal display method according to claim 1, wherein the steps (a) and (b) are alternately repeated.   3. The liquid crystal according to claim 1, further comprising a step of supplying a selection signal to two or more of the plurality of row lines and supplying a black display signal to each of the plurality of column lines. Display method.   The liquid crystal display method according to claim 1, wherein m> 115.   4. The liquid crystal display method according to claim 3, wherein the two or more row lines are (n + α · m) (α = 1, 2,..., P (p: positive integer)). A liquid crystal display method characterized by the above-mentioned.   4. The liquid crystal display method according to claim 3, wherein the two or more row lines are (n + α · m + k−1) (α = 1, 2,..., P (p, k: positive) from the (n + α · m) th line. )) A liquid crystal display method characterized in that the lines are lines up to the first line.   7. The liquid crystal display method according to claim 1, wherein a supply time of the data signal is equal to a supply time of the black display signal.   7. The liquid crystal display method according to claim 1, wherein a supply time of the data signal is longer than a supply time of the black display signal. 9. The liquid crystal display method according to claim 1, wherein the value of m is set so as to satisfy the following equation.
fxm / N> t
Here, N: number of lines f: one frame time t: response time of the liquid crystal when switching from white display to black display 7. The liquid crystal display method according to claim 6, wherein the value of k is set so as to satisfy the following relationship.
T × k ≧ T _0, where T: one supply time of the black display signal T ₀ : the shortest time of the black display signal that can completely switch the white display to the black display 11. The liquid crystal display method according to claim 1, wherein a voltage Vd when the data signal is a data signal for black display and a voltage Vr of the black display signal are set as follows. A liquid crystal display method characterized by setting so as to satisfy the relationship.
Vd <Vr at the time of normally white in the case of positive polarity with respect to the potential level of the counter electrode
Vd> Vr when normally black
Vd> Vr at the time of normally white in the case of negative polarity with respect to the potential level of the counter electrode
Vd <Vr when normally black A plurality of column lines arranged in parallel with each other, a plurality of row lines arranged in parallel with each other intersecting the plurality of column lines, and an intersection of the plurality of column lines and the plurality of row lines. Liquid crystal having a display panel having a plurality of picture elements provided correspondingly, a column line driver supplying a data signal to the plurality of column lines, and a row line driver supplying a selection signal to the plurality of row lines In the display device,
A display control unit that supplies a video signal and a control signal to the column line driver, and supplies a control signal to the row line driver to control an image display operation on the display panel; Black display signal generating means for generating a black display signal for displaying
A changeover switch is provided in the column line driver, and selects one of a data signal based on a video signal from the display control unit and a black display signal from the black display signal generation unit.
The display control unit supplies the control signal for selecting the row line to the row line driver, and when the changeover switch is selecting a data signal, the display control unit switches from the nth to the (n + m−1) th (n And m is a positive integer), the selection signal is supplied to one of the row lines, and when the changeover switch selects the black display signal, the selection signal is supplied to one of the row lines. A selection signal is supplied to at least one of the l-th row lines (1 is a positive integer, l ≧ n + m or l + m ≦ n) to l + m−1, and each of the plurality of picture elements In the above, the data signal and the black display signal are supplied in one frame period, and the black display signal is supplied in each of the plurality of picture elements for a time exceeding 4 / 16.7 of the one frame period. The feature is that the state is maintained The liquid crystal display device that.   13. The liquid crystal display device according to claim 12, wherein the changeover switch alternately switches and selects the data signal and the black display signal.   14. The liquid crystal display device according to claim 12, wherein a selection signal is supplied to two or more of the plurality of row lines when the changeover switch is selecting a black display signal.   The liquid crystal display device according to claim 12, wherein m> 115.   16. The liquid crystal display device according to claim 12, wherein the plurality of row lines are divided into L (L: positive integer) blocks every m lines, and the row line driver includes: A liquid crystal display device comprising L partial row line drivers for supplying a selection signal to a row line of each block.   The liquid crystal display device according to any one of claims 12 to 16, wherein the control signal from the display control unit to the column line driver is a switching control signal for controlling a switching operation of the switch. The switching control signal includes a selection time of the data signal longer than a selection time of the black display signal.   The liquid crystal display device according to any one of claims 12 to 16, wherein the control signal from the display control unit to the column line driver is a switching control signal for controlling a switching operation of the switch. The liquid crystal display device, wherein the switching control signal includes a selection time of the data signal and a selection time of the black display signal.   16. The liquid crystal display device according to claim 15, wherein a control signal from the display control unit to the row line driver is an identification signal for identifying whether or not a black display signal supply period for supplying the black display signal. And the row line driver performs the (n + m) -th to (n + m + k-1) -th (k is a positive integer, k> 1) rows in the black display signal supply period based on the identification signal. A liquid crystal display device adapted to supply the selection signal to a line.   20. The liquid crystal display device according to claim 19, wherein a control signal from the display control unit to the row line driver includes a scan start signal, wherein the row line driver includes a shift register having a plurality of latch circuits, and the identification signal. The scan start signal is supplied to the first latch circuit of the shift register during the data signal supply period, while the scan start signal is supplied to the mth latch circuit of the shift register during the black display signal supply period. A liquid crystal display device comprising: a scan start signal supply unit that supplies a scan start signal supply unit that supplies the scan start signal supply unit to k consecutive latch circuits.   21. The liquid crystal display device according to claim 20, wherein the scanning start signal supply means is capable of changing a latch circuit number m and a latch circuit number k during the black display signal supply period. .   22. The liquid crystal display device according to claim 21, further comprising supply control means for controlling an operation of said scan start signal supply means, wherein said supply control means controls said latch circuit based on an external scan start position designation signal. A liquid crystal display device which outputs a control signal for setting a number m to the scanning start signal supply means.   23. The liquid crystal display device according to claim 12, wherein the display control unit performs a black display signal supply operation based on an operation of the changeover switch in response to an external command signal. A control signal for the first display mode and a control signal for the second display mode in which the operation of the switch is stopped and the supply operation of the black display signal is not performed are output by switching. Liquid crystal display.   24. The liquid crystal display device according to claim 23, further comprising: a signal reference power supply for setting a voltage of a data signal supplied from the column line driver, wherein the voltage of the signal reference power supply is in the first display mode. A liquid crystal display device capable of switching between a time and a second display mode.   24. The liquid crystal display device according to claim 23, wherein data relating to the same position on a screen is monitored based on a video signal from the display control unit, and whether an image based on the video signal is a moving image or a still image. A liquid crystal display device comprising: a moving image / still image determining unit that determines the above and outputs the command signal representing the determination result to the display control unit.   The liquid crystal display device according to any one of claims 23 to 25, wherein the first display mode and the second display mode are based on a backlight that irradiates the display panel from the back side, and the command signal. And a backlight dimming means for switching the brightness of the backlight.   27. The liquid crystal display device according to claim 12, wherein the black display signal generating means is a power supply for a black display signal, and a voltage of the power supply for the black display signal is changeable. A liquid crystal display device characterized by the above-mentioned.

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