METHOD FOR DRIVING LIQUID CRYSTAL DISPLAY DEVICE

• US 20110157131A1
• Filed: 12/22/2010
• Published: 06/30/2011
• Est. Priority Date: 12/25/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Miyake, Hiroyuki
• Granted Patent: US 9,852,703 B2
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2300/0404 Matrix technologies
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12

Abstract

An object is to suppress deterioration of a displayed image even when a refresh rate is reduced in displaying a still image. A liquid crystal display device includes a pixel transistor electrically connected to a pixel electrode, and a capacitor having one electrode electrically connected to the pixel electrode and the other electrode electrically connected to a capacitor line. The pixel transistor is turned on and a voltage based on an image signal is supplied to the pixel electrode, and then, the pixel transistor is turned off so that a holding period during which the pixel electrode holds the voltage based on the image signal starts. A holding signal corresponding to change of the voltage based on the image signal in the pixel electrode in the holding period is supplied to the capacitor line so that a potential of the pixel electrode is constant.

Claims

1. A method for driving a liquid crystal display device including a transistor electrically connected to a pixel electrode, and a capacitor having a first electrode electrically connected to the pixel electrode and a second electrode electrically connected to a capacitor line, the method comprising the steps of:

turning on the transistor;

supplying a voltage to the pixel electrode through the transistor;

turning off the transistor; and

changing a voltage of the capacitor line while the voltage of the pixel electrode is held.

2. The method for driving a liquid crystal display device, according to claim 1, wherein the voltage of the capacitor line is changed in order to keep the voltage of the pixel electrode constant while the voltage of the pixel electrode is held.

3. The method for driving a liquid crystal display device, according to claim 1, wherein the transistor comprises an oxide semiconductor.

4. The method for driving a liquid crystal display device, according to claim 1, wherein the voltage of the pixel electrode is held for 60 seconds or longer.

5. The method for driving a liquid crystal display device, according to claim 1, wherein the liquid crystal display device is driven with frame inversion driving, common inversion driving, source line inversion driving, gate line inversion driving, or dot inversion driving per frame period.

6. The method for driving a liquid crystal display device, according to claim 1, wherein the voltage of the capacitor line is lowered while the voltage of the pixel electrode is held.

7. The method for driving a liquid crystal display device, according to claim 1, wherein the voltage of the capacitor line is raised while the voltage of the pixel electrode is held.