Liquid crystal display panel and method of driving the same

• US 20060145987A1
• Filed: 12/13/2005
• Published: 07/06/2006
• Est. Priority Date: 12/31/2004
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Hong, Hyung Ki
• Granted Patent: US 7,705,813 B2
• Time in Patent Office: Days
• US Class Current: 345/92
• CPC Class Codes: G02F 1/134381 Hybrid switching mode, i.e. for applying an electric field with components parallel and orthogonal to the substrates
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• 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

Abstract

This invention relates to a three electrode liquid crystal display panel that is adaptive for AC-driving liquid crystal cells inclusive of three electrodes, and a driving method thereof. A three electrode liquid crystal display panel according to an embodiment of the present invention includes first and second pixel electrodes disposed on a first substrate with an insulating film therebetween; and a common electrode disposed in a second substrate which is bonded with the first substrate with a liquid crystal therebetween, and wherein the first pixel electrode selectively supplies a maximum voltage and a minimum voltage, the common electrode supplies a medium voltage between the maximum voltage and the minimum voltage as a reference voltage, and the second pixel electrode supplies a positive data voltage and a negative data voltage on the basis of the reference voltage in a range between the maximum voltage and the minimum voltage, thereby AC-driving the liquid crystal.

Claims

1. A liquid crystal display panel, comprising:

a first pixel electrode is disposed on a first substrate with an insulating film therebetween and is selectively applied a maximum voltage and a minimum voltage;

a second pixel electrode is disposed on a first substrate with an insulating film therebetween and is applied a positive data voltage and a negative data voltage that are relative to the medium voltage and in a range between the maximum voltage and the minimum voltage; and

a common electrode is disposed on a second substrate which is bonded with the first substrate with a liquid crystal therebetween and is applied a medium voltage with a voltage level between the maximum voltage and the minimum voltage; and

wherein the liquid crystal is driven with alternating current.

3. The liquid crystal display panel according to any one of claims 1 and 2, further comprising:

a thin film transistor that is connected to the second pixel electrode on the first substrate and that supplies the positive and negative data voltages from a drive circuit; and

a gate line and a data line which are connected to the thin film transistor.

4. The liquid crystal display panel according to claim 3, further comprising:

a pad that is connected to the first pixel electrode on the first substrate and that supplies the maximum voltage and the minimum voltage from the drive circuit.

5. The liquid crystal display panel according to claim 1, wherein as a voltage of the second pixel electrode diverges from a voltage of the first pixel electrode, as a horizontal electric field component increases to drive the liquid crystal in a white state, and as the voltage of the second pixel electrode converges to the voltage of the first pixel electrode, a vertical electric field component increases to drive the liquid crystal in a black state.

6. The liquid crystal display panel according to claim 1, wherein a positive voltage is applied to the liquid crystal if the maximum voltage is applied to the first pixel electrode and the positive data voltage is applied to the second pixel electrode, and a negative voltage is applied to the liquid crystal if the minimum voltage is applied to the first pixel electrode and the negative data voltage is applied to the second pixel electrode.

7. The liquid crystal display panel according to claim 3, wherein the common electrode covers the entire surface of the second substrate, and the first pixel electrode has a structure including a plurality of stripes corresponding to a line of liquid crystal cells that are defined by the crossing of the gate line and the data line.

8. The liquid crystal display panel according to claim 7, wherein the first pixel electrode has a dot electrode structure for each liquid crystal cell, and the first pixel electrode is commonly connected to a first pixel electrode in another liquid crystal cell with the same polarity.

9. The liquid crystal display panel according to claim 8, wherein any one voltage of the maximum voltage and the minimum voltage, which is opposite to that of an adjacent first pixel electrode in vertical and horizontal directions, is applied to the first pixel electrode, and a data voltage of a polarity, which is opposite to that of an adjacent second pixel electrode in the vertical and horizontal directions, is applied to the second pixel electrode, thereby inverting the polarity of each liquid crystal cell.

10. The liquid crystal display panel according to claim 7, wherein the first pixel electrode covers an entire surface of the first substrate.

11. The liquid crystal display panel according to claim 10, wherein the maximum voltage and the minimum voltage are alternatively applied to the first pixel electrode for each frame, and the positive and negative data voltages are alternatively applied to the second pixel electrode for each frame, thereby inverting the polarity of the liquid crystal cell each frame.

12. The liquid crystal display panel according to claim 10, wherein the maximum voltage and the minimum voltage are alternatively applied to the common electrode for each frame, and the positive and negative data voltages are alternatively applied to the second pixel electrode for each frame, thereby inverting the polarity of the liquid crystal cell each frame.

13. The liquid crystal display panel according to claim 7, wherein the first pixel electrode is formed in a line electrode structure where the first pixel electrode is divided for each vertical or horizontal line.

14. The liquid crystal display panel according to claim 13, wherein the maximum voltage and the minimum voltage are alternatively applied to the first pixel electrode for each horizontal or vertical line, and the positive and negative voltages are alternatively applied to the second pixel electrode for each horizontal or vertical line, thereby inverting the polarity of the liquid crystal cell for each horizontal or vertical line.

15. The liquid crystal display panel according to claim 13, wherein when the first pixel electrode is divided for each horizontal line, thin film transistors along a horizontal line are alternately connected to two adjacent gate lines.

16. The liquid crystal display panel according to claim 15, wherein the data line supplies a data voltage of which the polarity is inverted for each horizontal and vertical line, thereby making the polarity of the liquid crystal cell inverted for each cell.

2. A liquid crystal display panel, comprising:

a first pixel electrode is disposed on a first substrate with an insulating film therebetween and is applied is applied a medium voltage with a voltage level between the maximum voltage and the minimum voltage;

a second pixel electrode is disposed on a first substrate with an insulating film therebetween and is applied a positive data voltage and a negative data voltage that are relative to the medium voltage and in a range between the maximum voltage and the minimum voltage; and

a common electrode is disposed on a second substrate which is bonded with the first substrate with a liquid crystal therebetween and is selectively applied a maximum voltage and a minimum voltage; and

wherein the liquid crystal is driven with alternating current.

17. A driving method of a liquid crystal display panel, comprising:

selectively applying a maximum voltage and a minimum voltage to a first pixel electrode formed on a first substrate;

applying a medium voltage with a voltage level between the maximum voltage and the minimum voltage to a common electrode of a second substrate, which together with the first substrate has a liquid crystal therebetween; and

applying a positive data voltage and a negative data voltage that are relative to the medium voltage and in a range between the maximum voltage and the minimum voltage to a second pixel electrode which overlaps the first pixel electrode with an insulating film therebetween, and

wherein the liquid crystal is driven with alternating current.

19. The driving method according to any one of claims 17 and 18, wherein the positive and negative data voltages are applied using a data line and a thin film transistor.

20. The driving method according to claim 17, wherein the maximum voltage and the minimum voltage are applied through a pad.

21. The driving method according to claim 17, wherein as a voltage of the second pixel electrode diverges from a voltage of the first pixel electrode, a horizontal electric field component increases to drive the liquid crystal in a white state, and as the voltage of the second pixel electrode converges to the voltage of the first pixel electrode, a vertical electric field component increases to drive the liquid crystal in a black state.

22. The driving method according to claim 17, wherein a positive voltage is applied to the liquid crystal if the first pixel electrode applies the maximum voltage and the second pixel electrode applies the positive data voltage, and a negative voltage is applied to the liquid crystal if the first pixel electrode applies the minimum voltage and the second pixel electrode applies the negative data voltage.

23. The driving method according to claim 17, wherein the first pixel electrode formed in a dot electrode structure for each liquid crystal cell applies any one voltage of the maximum voltage and the minimum voltage which is opposite to that of an adjacent first pixel electrode in vertical and horizontal directions, and the second pixel electrode which is independent for each liquid crystal cell applies a data voltage of a polarity which is opposite to that of an adjacent second pixel electrode in the vertical and horizontal directions, thereby inverting the polarity of each liquid crystal cell.

24. The driving method according to claim 17, wherein the first pixel electrode covers an entire surface of the first substrate and the maximum voltage and the minimum voltage for each frame are alternatively applied to the first pixel electrode, and the positive and negative data voltages for each frame are4 alternatively applied to the second pixel electrode, which is independent for each liquid crystal cell, thereby inverting the polarity of the liquid crystal cell for each frame.

26. The driving method according to claim 17, wherein the maximum voltage and the minimum voltage for each horizontal line are alternatively applied to the first pixel electrode divided for each horizontal line, and the positive and negative voltages for each horizontal line are alternatively applied to the second pixel electrode which is independent for each liquid crystal cell, thereby inverting the polarity of each horizontal line.

27. The driving method according to claim 17, wherein the maximum voltage and the minimum voltage for each vertical line are alternatively applied to the first pixel electrode divided for each vertical line, and the positive and negative voltages for each vertical line are alternatively applied to the second pixel electrode, which is independent for each liquid crystal cell, thereby inverting the polarity of the liquid crystal cell for each vertical line.

28. The driving method according to claim 17, wherein when the second pixel electrode is divided for each liquid crystal cell and connected to a thin film transistor and the thin film transistor is alternately connected to two adjacent gate lines, the first pixel electrode alternately applies the maximum voltage and the minimum voltage for each horizontal line, and a data line connected to the thin film transistor applies a data voltage of which the polarity is inverted for each horizontal and vertical line, thereby inverting the polarity of the liquid crystal cell for each horizontal line.

18. A driving method of a liquid crystal display panel, comprising:

selectively applying a maximum voltage and a minimum voltage to a common electrode formed on a first substrate;

applying a medium voltage with a voltage level between the maximum voltage and the minimum voltage to a first pixel electrode of a second substrate, which together with the first substrate has a liquid crystal therebetween; and

applying a positive data voltage and a negative data voltage that is relative to the medium voltage in a range between the maximum voltage and the minimum voltage to a second pixel electrode, which overlaps the first pixel electrode with an insulating film therebetween, and

wherein the liquid crystal is driven with alternating current.

25. The driving method according to claim 18, wherein the common electrode covers an entire surface of the second substrate and the maximum voltage and the minimum voltage for each frame are alternatively applied to the common electrode, and the positive and negative data voltages for each frame are alternatively applied to the second pixel electrode which is independent for each liquid crystal cell, thereby inverting the polarity of the liquid crystal cell for each frame.