Sharp Kabushiki Kaisha Corporation

Norio Ohmura

Tatsuhiko Suyama

Noriyuki Tanaka

Kouji Kumada

Takuya Sone

Kentaroh Uemura

Toshiya Aoki

Makoto Yokoyama

Jin Miyazawa

In a liquid crystal display device, a drive unit is controlled in a direction of eliminating a polarity bias of a data voltage corresponding to image data at a point of time when a refresh signal for updating an image displayed on a display unit by periodical refreshment or forced refreshment is generated, and the polarity bias is obtained for each of subsequent frame periods. In this manner, not only the polarity bias after the point of time when the refresh signal is generated is obtained so that the polarity bias at the point of time when the refresh signal is generated is eliminated, but also the polarity bias is repeatedly obtained in the same way every time the refresh signal is generated, and accordingly, the polarity bias can be prevented from being increased.

Liquid crystal display device and method for driving same

When a SLEEPIN Command is inputted to the liquid crystal display device, the liquid crystal display device controls a source driver and a gate driver to generate an alternating current voltage and apply the generated alternating current voltage to a liquid crystal layer, in order to eliminate charge storage due to impurity ions distributed unevenly due to a polarity bias caused by a voltage applied to the liquid crystal layer until a point of time when the Command is inputted. In this manner, the liquid crystal display device shifts to a sleep period in a state where the charge storage due to the unevenly distributed impurity ions is eliminated. Therefore, when the liquid crystal display device resumes from the sleep period, generation of an afterimage due to burn-in of liquid crystal and generation of a flicker due to deviation of an optimum common voltage do not occur.

In a liquid crystal display device, it is determined whether or not image data inputted from the outside has changed from image data of the previous frame by comparing those image data with respect to each line. As a result, when it is determined that the image data has changed, an entire screen is not rewritten, but image data from a top of a screen as a fixed position to a last line with the image data having changed are read from a frame memory and written into a pixel formation portion. Accordingly, of the screen for one frame, a screen from a top thereof to the last line where the image change has been detected is updated, and on subsequent lines, an image of the previous frame is continuously displayed.

Image display device

Provided are a liquid crystal display device and a driving method therefor that do not cause problems such as occurrence of flicker even when performing pause driving. When an off signal Soff instructing to turn off power is inputted, a polarity bias value W at the power-off is stored in a balance storage circuit. When the power is turned on again, the polarity bias value W is read from the balance storage circuit and provided to a balance control circuit. The balance control circuit starts insertion of a pause frame period to cancel out the polarity bias value W. By this, decrementing the polarity bias value W by '1' every insertion of a pause frame period is repeated. Then, at a point of time when the polarity bias value W becomes '0', insertion of a pause frame period is ceased and normal pause driving is performed.

Liquid crystal display device including display control circuitry configured to store a polarity bias value

In a liquid crystal display device for performing pause driving, occurrence of flicker is effectively suppressed while an increase in power consumption is suppressed. When a frame in which an image signal (DAT) is inputted from an external portion without output of a request signal (RO) for requesting the external portion to input the image signal (DAT) is defined as a first input frame, a reversal driving control portion () sets the reversal driving technique in the first input frame to the column-reversal driving while setting the first input frame to a refresh frame defined as a first refresh frame, sets three frames subsequent to the first refresh frame to pause frames, sets a frame subsequent to the final pause frame to a refresh frame defined as a second refresh frame, and sets the reversal driving technique in the second refresh frame to the dot-reversal driving.

Provided is a liquid crystal display device capable of reliably reducing power consumption during pause drive by controlling the timing of performing refresh. When there is an image change in externally inputted RGB data, or when the number of consecutive pause frames reaches a predetermined value, if the number of immediately preceding pause frames is less than a threshold BCTH, image signal refresh is performed once, or if the number of pause frames is greater than or equal to the threshold BCTH, boost charge refresh is performed first, and then, the image signal refresh is performed. As a result, it is rendered possible to reduce flicker due to luminance reduction, and it is also rendered possible to eliminate the need to perform refresh consecutively even if the frequency of RGB data is high (e.g., 30 Hz) during pause drive.

In a liquid crystal display device for performing pause driving, occurrence of flicker is effectively suppressed while an increase in power consumption is suppressed. When an image change determination portion () detects an image change in a period from the previous refresh frame until generation of a predetermined number of times of pause frames, a reversal driving control portion () sets the next frame after a frame where an image change has been detected to a refresh frame where a reversal driving technique is a column-reversal driving. When the image change determination portion () does not detect an image change in the period from the previous refresh frame until generation of the predetermined number of times of pause frames, the reversal driving control portion () sets the next frame after the final pause frame to a refresh frame where a reversal driving technique is a dot-reversal driving.

In a liquid crystal display device for performing pause driving, occurrence of flicker is effectively suppressed while an increase in power consumption is suppressed. A frame in which an image signal is inputted without requesting an external portion to input the image signal is set as a refresh frame by a reversal driving technique deciding portion. A pause frame counting portion counts the number of times of pause frames since the previous refresh frame as a count value. The comparison portion compares the count value with a previously set threshold. As a result, when the count value is not smaller than the threshold, the reversal driving technique deciding portion sets a reversal driving technique in the first input frame to dot-reversal driving. When the count value is smaller than the threshold, the reversal driving technique deciding portion sets a reversal driving technique in the first input frame to column-reversal driving.

A liquid crystal display apparatus is disclosed, which is capable of suppressing sound emission caused by the AC drive of liquid crystal while suppressing an increase in power consumption. A non-active period during which polarity reversal of a common electrode signal (VCOM) is repeated at predetermined intervals is provided in each horizontal scanning period. During an active period, a common electrode drive circuit provides a common electrode signal (VCOM) indicating either one of potentials LVand LVto a common electrode, based on a polarity instruction signal (POL). During the non-active period, the common electrode drive circuit provides a common electrode signal (VCOM) whose potential changes between LVand LVto the common electrode, based on a reversal timing control signal (CTRL). Here, the amplitude of the common electrode signal (VCOM) for the non-active period is made smaller than the amplitude of the common electrode signal (VCOM) for the active period.

Liquid crystal display apparatus, drive circuit therefor, and drive method therefor

An input signal INDATA inputted to a sender-side interface portion is encoded by an encoder, and a transmission signal generated by the encoding is transmitted to a receiver-side interface portion through two signal transmission lines. The input signal INDATA is encoded in such a manner that the logic level of the transmission signal transmitted through at least one of the two signal transmission lines is changed in any two consecutive elementary periods. The receiver-side interface portion is provided with a clock receiver, and a clock signal is generated based on the change of the transmission signals supplied from the two signal transmission lines.

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Osaka, Japan

Norio Ohmura