LIQUID-CRYSTAL DISPLAY DEVICE AND DRIVE METHOD THEREOF

• US 20150243253A1
• Filed: 08/09/2013
• Published: 08/27/2015
• Est. Priority Date: 09/28/2012
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sone, Takuya, Tanaka, Noriyuki
• Granted Patent: US 9,818,375 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2310/0278 Details of driving circuits arranged to drive both scan and data electrodes
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 2370/022 Centralised management of display operation, e.g. in a server instead of locally
• CPC Class Codes: G09G 3/2096 Details of the interface to the display terminal specific for a flat panel suitable for both CRT and flat panel G09G5/006; specific for a CRT G09G1/167
• 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 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• 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

Provided are a liquid crystal display device and a drive method thereof, capable of promptly making an afterimage, which is visually recognized during pause drive, visually unrecognizable while suppressing power consumption. When updated image data is transmitted, a first refresh is performed by used of this image data, and a refresh pauses based on Ref_int just in the next two-frame period. Then, the second and third refreshes are consecutively performed, and a refresh pause is repeated until the next updated image data is transmitted. In this case, since a refresh can be performed three times in a short period after reception of the updated image data, it is possible to make liquid crystal molecules oriented in a direction corresponding to an applied voltage in a short time and make an afterimage visually unrecognizable.

Claims

1. A liquid crystal display device which performs pause drive at a predetermined refresh rate, the device comprising:

a display portion including a plurality of pixel formation portions;

a drive portion for driving the display portion; and

a display control portion for controlling the drive portion based on data received from the outside,

wherein, when image data included in the data is updated, the display control portion performs a refresh once by use of the updated image data, and then makes a refresh pause just in a pause period that is decided in accordance with a refresh rate of the image data, and after the end of the pause period, the display control portion performs a refresh at least once or more by use of the same image data as the updated image data.

2. The liquid crystal display device according to claim 1, wherein the number of times of refreshes performed after the end of the pause period is two.

3. The liquid crystal display device according to claim 2, wherein twice of refreshes, which are performed after the end of the pause period, are consecutively performed.

4. The liquid crystal display device according to claim 2, wherein twice of refreshes, which are performed after a lapse of the pause period, are performed with a period for making a refresh pause therebetween.

5. The liquid crystal display device according to claim 1, wherein the predetermined refresh rate is irregularly switched, and when the refresh rate is changed, a length of the pause period is also changed accordingly.

6. The liquid crystal display device according to claim 1, wherein the predetermined refresh rate is irregularly switched, and even when the refresh rate is changed, a length of the pause period is constant.

7. The liquid crystal display device according to claim 1, wherein

the display control portion performs control for AC drive, and

a plurality of positive polarity frames made up of a refresh frame for performing a refresh with positive polarity and a non-refresh frame for holding the positive polarity and a plurality of negative polarity frames made up of a refresh frame for performing a refresh with negative polarity and a non-refresh frame for holding the negative polarity are alternately provided in approximately the same proportion.

8. The liquid crystal display device according to claim 1, wherein, when the display control portion receives new data from the outside, the data including image data for updating a screen of the display portion at the time of performing a refresh or making a refresh pause, the display control portion stops the refresh or the refresh pause, performs a refresh once by use of the image data included in the new data, then makes a refresh pause just in the pause period that is decided in accordance with a refresh rate of the image data, and performs a refresh at least once or more by use of the same image data as the updated image data after the end of the pause period.

9. The liquid crystal display device according to claim 8, wherein, when the image data included in the data received from the outside has not been updated, the display control portion makes a refresh pause that is performed after the end of the pause period.

10. The liquid crystal display device according to claim 8, wherein

the display control portion includes a frame memory that stores the image data included in the data just for one frame, and

when not receiving the updated image data from the outside, the display control portion performs a refresh once by use of the image data read from the frame memory, and makes a refresh pause after the end of the pause period.

11. The liquid crystal display device according to claim 1, wherein the pixel formation portion includes a thin-film transistor having a control terminal connected to a scanning line in the display portion, a first conduction terminal connected to a signal line in the display portion, a second conduction terminal connected to a pixel electrode in the display portion, which is to be applied with a voltage in accordance with an image to be displayed, and a channel layer formed of an oxide semiconductor.

12. The liquid crystal display device according to claim 11, wherein the oxide semiconductor is InGaZnOx mainly composed of indium (In), gallium (Ga), zinc (Zn) and oxygen (O).

13. A method for driving a liquid crystal display device which includes a display portion including a plurality of pixel formation portions, a drive portion for driving the display portion, and a display control portion for controlling the drive portion based on data received from the outside, the device performing pause drive at a predetermined refresh rate, the method comprising the steps of:

performing a refresh once by use of updated image data when image data included in the data is updated;

making a refresh pause just in a pause period that is decided in accordance with a refresh rate of the image data; and

performing a refresh at least once or more by use of the same image data as the updated image data after the end of the pause period.