PIXEL AND DRIVING METHOD THEREOF FOR OPTICALLY COMPENSATED BEND MODE LIQUID CRYSTAL DISPLAY

• US 20080278646A1
• Filed: 03/25/2008
• Published: 11/13/2008
• Est. Priority Date: 05/08/2007
• Status: Abandoned Application

• Current Assignee: Chunghwa Picture Tubes Limited
• Original Assignee: Chunghwa Picture Tubes Limited
• Inventors: Cheng, Jung-Chieh, Chen, Szu-Fen, Chien, Yao-Hong, Wang, Chih-Chieh, Chen, Li-Shan
• Application Number:
  US12/054,396
• Publication Number:
  US 20080278646A1
• Time in Patent Office: Days
• US Class Current: 349/39
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/1395 Optically compensated birefringence [OCB]- cells or PI- cells

Abstract

A pixel including a transistor, a liquid crystal capacitor, a storage capacitor and a coupling capacitor is provided. The first end of the transistor is connected to a data line, the liquid crystal capacitor and the storage capacitor are coupled between the second end of the transistor and a common voltage, and the coupling capacitor is connected between the second end of the transistor and a select line. After a driving voltage is outputted to the liquid crystal capacitor and the storage capacitor by the data line, the select line inputs a pulse signal to the liquid crystal capacitor through the coupling capacitor. The pulse signal is capable of increasing the ability of the electric field for driving the liquid crystal so that the liquid crystal can still display normally in the bend state even though the lowest pixel voltage is lower than the critical voltage.

Claims

1. A pixel, comprising:

a transistor, having a first end coupled to a data line;

a liquid crystal capacitor, coupled to between a second end of the transistor and a common voltage; and

a coupling capacitor, coupling between the second end of the transistor and a select line.

2. The pixel of claim 1, wherein a gate of the transistor is coupled to a scan line and the second end of the transistor.

3. The pixel of claim 1, further comprising a storage capacitor connected in parallel with the liquid crystal capacitor.

4. The pixel of claim 1, wherein the select line outputs an over-driving voltage to the coupling capacitor and couples to the liquid crystal capacitor after a voltage is output to the liquid crystal capacitor through the data line.

5. The pixel of claim 4, wherein the over-driving voltage is an impulse signal.

6. The pixel of claim 1, wherein the pixel is suitable for an Optically Compensated Bend mode Liquid Crystal Display.

7. The pixel of claim 1, wherein the transistor is a thin film transistor.

8. A liquid crystal display, comprising:

a first scan line, corresponding to a plurality of first pixels;

a plurality of data lines, for driving the first pixels; and

a first select line, for outputting a first over-driving voltage to the first pixels according to driving polarities of the data lines;

wherein the first select line outputs the first over-driving voltage to the first pixels after charging the first pixels through the data lines.

9. The liquid crystal display of claim 8, further comprising:

a second scan line, corresponding to a plurality of second pixels; and

a second select line, for outputting a second over-driving voltage to the second pixels according to driving polarities of the data lines;

wherein the second select line outputs the second over-driving voltage to the second pixels after charging the second pixels through the data lines.

10. The liquid crystal display of claim 8, wherein the first pixel comprises:

a transistor, having a first end coupled to the first data line and a gate coupled to the first scan lie;

a liquid crystal capacitor, coupled between a second end of the transistor and a common voltage; and

a coupling capacitor, coupled between the second end of the transistor and the first select line.

11. The liquid crystal display of claim 10, wherein the first pixel further comprises a storage capacitor connected in parallel with the liquid crystal capacitor and coupled to the second end of the transistor.

12. The liquid crystal display of claim 10, wherein the transistor is a thin film transistor.

13. The liquid crystal display of claim 8, wherein the first over-driving voltage is an impulse signal.

14. The liquid crystal display of claim 8, wherein the liquid crystal display is an Optically Compensated Bend mode Liquid Crystal Display.

15. A liquid crystal display, comprising:

a first data line, for driving a plurality of first pixels; and

a first select line, for outputting a first over-driving voltage to the first pixels according to a driving polarity of the first data line;

wherein the first select line outputs the first over-driving voltage to the first pixels after charging the first pixels through the first data line.

16. The liquid crystal display of claim 15, further comprising:

a second data line, for driving a plurality of second pixels; and

a second select line, for outputting a second over-driving voltage to the second pixels according to a polarity of the second data line;

wherein the first second line outputs the second over-driving voltage to the second pixels after charging the second pixels through the second data line.

17. The liquid crystal display of claim 15, wherein the first pixel comprises:

a transistor, having a first end coupled to the first data line and a gate coupled to the first scan lie;

a liquid crystal capacitor, coupled between a second end of the transistor and a common voltage;

a coupling capacitor, coupled between the second end of the transistor and the first select line; and

a storage capacitor, connected in parallel with the liquid crystal capacitor and coupled to the second end of the transistor.

18. A liquid crystal display, comprising:

a scan line, corresponding to a first pixel and a second pixel, wherein the first pixel corresponds to a first data line and the second pixel corresponds to a second data line;

a first select line, outputting a first over-driving voltage to the first pixel according to a driving polarity of the first data line; and

a second select line, outputting a second over-driving voltage to the second pixel according to a driving polarity of the second data line;

wherein the first select line outputs the first over-driving voltage to the first pixel after charging the first pixel through the first data line, and the second select line outputs the second over-driving voltage to the second pixel after charging the second pixel through the second data line, wherein the first pixel and the second pixel are adjacent to each other and the driving polarity of the first data line and the second data line are opposite to each other.

19. The liquid crystal display of claim 18, wherein the first pixel comprises:

a transistor, having a first end coupled to the first data line and a gate coupled to the first scan line;

a liquid crystal capacitor, coupled between a second end of the transistor and a common voltage;

a coupling capacitor, coupling between the second end of the transistor and the first select line; and

a storage capacitor, connected in parallel with the liquid crystal capacitor.

20. A pixel driving method, comprising:

providing a voltage to a pixel; and

coupling an over-driving voltage to the pixel through a coupling capacitor.

21. The pixel driving method of claim 20, wherein the voltage is provided through a data line and the over-driving voltage is provided through a select line.

22. The pixel driving method of claim 20, wherein the over-driving voltage is an impulse signal.

23. A pixel structure, comprising:

a substrate;

an insulation layer, formed on the substrate;

a passivation layer, formed on the insulation layer;

a pixel electrode, formed on the passivation layer;

a common voltage connecting line, formed between the substrate and the insulation layer; and

a select line, formed between the substrate and the insulation layer;

wherein the common voltage connecting line and a pixel electrode form a storage capacitor, and the select line and the pixel electrode form a coupling capacitor.

24. The pixel structure of claim 23, wherein the select line is formed using a first metal layer.

25. The pixel structure of claim 23, wherein the common voltage connecting line is formed using the first metal layer.

26. A pixel structure, comprising:

a substrate;

an insulation layer, formed on the substrate;

a passivation layer, formed on the insulation layer;

a pixel electrode, formed on the passivation layer;

a common voltage connecting line, formed between the substrate and the insulation layer; and

a select line, formed between the insulation layer and the passivation layer;

wherein the common voltage connecting line and a pixel electrode form a storage capacitor, and the select line and the pixel electrode form a coupling capacitor.

27. The pixel structure of claim 26, wherein the common voltage connecting line is formed using a first metal layer.

28. The pixel structure of claim 26, wherein the second line is formed using a second metal layer.