Liquid crystal display device and method of driving the same

• US 20070146288A1
• Filed: 06/05/2006
• Published: 06/28/2007
• Est. Priority Date: 12/28/2005
• Status: Active Grant

• Current Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Original Assignee: LG Display Co., Ltd.
• Inventors: Byun, Seung Chan
• Granted Patent: US 7,561,138 B2
• Time in Patent Office: Days
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

A display device according to the present invention includes a pixel array including a plurality of gate lines and a plurality of data lines crossing each other to define pixel regions and a plurality of first thin film transistors near the crossings, the first thin film transistors supplying pixel voltages to pixel electrodes of the pixel regions; a gate driving circuit to sequentially supply a scanning pulse to the gate lines; a data driving circuit to supply the pixel voltages to the data lines; and a pre-charging circuit including a plurality of second thin film transistors, the second thin film transistor connected to the nth (wherein, n is an integer) gate line and turned on by the scanning pulse applied to the nth gate line, the pre-charging circuit supplying a voltage higher than a threshold voltage of the first thin film transistors to the (n+2)th gate line.

Claims

1. A display device, comprising:

a pixel array including a plurality of gate lines and a plurality of data lines crossing each other to define pixel regions and a plurality of first thin film transistors near the crossings, the first thin film transistors supplying pixel voltages to pixel electrodes of the pixel regions;

a gate driving circuit to sequentially supply a scanning pulse to the gate lines;

a data driving circuit to supply the pixel voltages to the data lines; and

a pre-charging circuit including a plurality of second thin film transistors, the second thin film transistor connected to the nth gate line and turned on by the scanning pulse applied to the nth gate line, the pre-charging circuit supplying a voltage higher than a threshold voltage of the first thin film transistors to the (n+2)th gate line.

2. The display device according to claim 1, wherein the pre-charging circuit further includes:

a first voltage supply line supplied with a first alternating current gate-on voltage; and

a second voltage supply line supplied with a second alternating current gate-on voltage.

3. The display device according to claim 2, wherein a voltage level of the first alternating current gate-on voltage and a voltage level of the second alternating current gate-on voltage are changed every two horizontal periods.

4. The display device according to claim 3, wherein a phase of the first alternating current gate-on voltage is opposite to a phase of the second alternating current gate-on voltage.

5. The display device according to claim 4, wherein the plurality of second thin film transistors include:

the nth second thin film transistor having a gate terminal connected to the nth gate line, a source terminal connected to the first voltage supply line, and a drain terminal connected to the (n+2)th gate line;

the (n+1)th second thin film transistor having a gate terminal connected to the (n+1)th gate line, a source terminal connected to the first voltage supply line, and a drain terminal connected to the (n+3)th gate line;

the (n+2)th second thin film transistor having a gate terminal connected to the (n+2)th gate line, a source terminal connected to the second voltage supply line, and a drain terminal connected to the (n+4)th gate line; and

the (n+3)th second thin film transistor having a gate terminal connected to the (n+3)th gate line, a source terminal connected to the second voltage supply line, and a drain terminal connected to the (n+5)th gate line.

6. The display device according to claim 1, wherein the pre-charging circuit is formed on the same substrate together with the gate lines, the data lines and the first thin film transistors.

7. The display device according to claim 2, further comprising a voltage generator for generating the first alternating current gate-on voltage and the second alternating current gate-on voltage.

8. The display device according to claim 1, wherein the data driving circuit supplies the pixel voltages to the data lines according to a dot inversion method.

9. The display device according to claim 1, wherein the data driving circuit supplies the pixel voltages to the data lines according to a line inversion method.

10. A method of driving a display device, the display device including a pixel array in which a plurality of gate lines cross a plurality of data lines to define pixel regions and a plurality of first thin film transistors near the crossings, the first thin film transistors supplying pixel voltages to pixel electrodes of the pixel regions, the method comprising:

sequentially supplying a scanning pulse to the gate lines;

supplying the pixel voltages to the data lines according to a dot inversion method; and

supplying a voltage higher than a threshold of the first thin film transistors to the (n+2)th gate line using a second thin film transistor turned on in accordance with the scanning pulse supplied to the nth gate line.

11. The method according to claim 10, wherein the voltage higher than the threshold of the first thin film transistors to the (n+2)th gate line includes a first alternating current gate-on voltage and a second alternating current gate-on voltage.

12. The method according to claim 11, wherein a voltage level of the first alternating current gate-on voltage and a voltage level of the second alternating current gate-on voltage are changed every two horizontal periods.

13. The method according to claim 12, wherein a phase of the first alternating current gate-on voltage is opposite to a phase of the second alternating current gate-on voltage.

14. The method according to claim 12, wherein said supplying the voltage higher than the threshold voltage includes:

supplying the first alternating current gate-on voltage to the (n+2)th gate line using the nth second thin film transistor connected to the nth gate line;

supplying the first alternating current gate-on voltage to the (n+3)th gate line using the (n+1)th second thin film transistor connected to the (n+1)th gate line;

supplying the second alternating current gate-on voltage to the (n+4)th gate line using the (n+2)th second thin film transistor connected to the (n+2)th gate line; and

supplying the second alternating current gate-on voltage to the (n+5)th gate line using the (n+3)th second thin film transistor connected to the (n+3)th gate line.

15. The method according to claim 10, wherein when supplying the voltage higher than the threshold of the first thin film transistors to the (n+2)th gate line using the nth second thin film transistor connected to the nth gate line, the first thin film transistors connected to the (n+4)th gate line are turned off.

16. A pre-charge device for pre-charging pixels of a display device having a plurality of gate lines and a plurality of data lines crossing each other and a plurality of first thin film transistors near the crossings for supplying pixel voltages to the pixels, the pre-charge device comprising:

a voltage generator to supply a voltage higher than a threshold voltage of the first thin film transistors; and

a plurality of second thin film transistors, one of the second thin film transistors turned on by a scanning pulse applied to the nth(wherein, n is an integer)gate line to supply the voltage higher than the threshold voltage of the first thin film transistors to the (n+2)th gate line.

17. The pre-charge device according to claim 16, wherein the pre-charge device further includes:

a first voltage supply line supplied with a first alternating current gate-on voltage; and

a second voltage supply line supplied with a second alternating current gate-on voltage.

18. The pre-charge device according to claim 17, wherein a voltage level of the first alternating current gate-on voltage and a voltage level of the second alternating current gate-on voltage are changed every two horizontal periods.

19. The pre-charge device according to claim 18, wherein a phase of the first alternating current gate-on voltage is opposite to a phase of the second alternating current gate-on voltage.

20. The pre-charge device according to claim 19, wherein the second thin film transistors include:

the nth second thin film transistor having a gate terminal connected to the nth gate line, a source terminal connected to the first voltage supply line, and a drain terminal connected to the (n+2)th gate line;

the (n+1)th second thin film transistor having a gate terminal connected to the (n+1)th gate line, a source terminal connected to the first voltage supply line, and a drain terminal connected to the (n+3)th gate line;

the (n+2)th second thin film transistor having a gate terminal connected to the (n+2)th gate line, a source terminal connected to the second voltage supply line, and a drain terminal connected to the (n+4)th gate line; and

the (n+3)th second thin film transistor having a gate terminal connected to the (n+3)th gate line, a source terminal connected to the second voltage supply line, and a drain terminal connected to the (n+5)th gate line.