Liquid crystal display and driving method thereof

• US 20050122295A1
• Filed: 12/02/2004
• Published: 06/09/2005
• Est. Priority Date: 12/04/2003
• 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: Sawabe, Daiichi
• Granted Patent: US 7,548,226 B2
• Time in Patent Office: Days
• US Class Current: 345/88
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• 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 3/3666 with the matrix divided into sections

Abstract

A liquid crystal display is driven at, for example, a frame frequency of 100 Hz or higher. There are provided a base-4 frame counter 2 and a source control signal generator section controlling the polarity of the liquid crystal in pixels so as to alternately repeat, for each frame, a horizontal reversal once every m lines (m is 2 or a greater positive integer) and a horizontal reversal once every m lines after shifting the polarity of the lines in the preceding frame by n lines (n is a positive integer equal to a half or less of m). The provision achieves a liquid crystal display and a method of driving the display, addresses insufficient charging at higher frame frequencies and accomplishing higher display quality.

Claims

1. A liquid crystal display in which pixels are driven by active matrix drive, the display comprising interframe polarity control means controlling to alternately repeat, for each frame, a first reversal pattern where a polarity of liquid crystal in the pixels is subjected to a horizontal reversal once every m lines (m is 2 or a greater positive integer) and a second reversal pattern where polarity reversal of lines in the first reversal pattern is shifted by n lines (n is a positive integer equal to a half or less of m).

2. The liquid crystal display as set forth in claim 1, further comprising:

a liquid crystal display screen composed of pixels arranged in a matrix;

gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in the pixels; and

source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels.

3. The liquid crystal display as set forth in claim 2, wherein:

the liquid crystal display screen is divided into two;

a first screen and a second screen;

the gate drive means is divided into two;

first gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in pixels in the first screen and second gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in pixels in the second screen; and

the source drive means is divided into two;

first source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels in the first screen and second source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels in the second screen.

4. The liquid crystal display as set forth in claim 2, wherein when implementing a horizontal reversal once every m lines, the gate drive means regulates a width of the gate pulse on lines in the m lines during a horizontal scan period equivalent to m lines.

5. The liquid crystal display as set forth in claim 3, wherein when implementing a horizontal reversal once every m lines, the gate drive means regulates a width of the gate pulse on lines in the m lines during a horizontal scan period equivalent to m lines.

6. The liquid crystal display as set forth in claim 2, wherein the gate drive means regulates a width of the gate pulse on lines in accordance with a polarity of pixels in a preceding line.

7. The liquid crystal display as set forth in claim 3, wherein the gate drive means regulates a width of the gate pulse on lines in accordance with a polarity of pixels in a preceding line.

8. The liquid crystal display as set forth in claim 2, wherein the source drive means regulates an output of the source voltage when implementing a horizontal reversal once every m lines.

9. The liquid crystal display as set forth in claim 3, wherein the source drive means regulates an output of the source voltage when implementing a horizontal reversal once every m lines.

10. The liquid crystal display as set forth in claim 8, wherein the source drive means includes source voltage switch means regulating the output of the source voltage by switching between predetermined two source voltages in accordance with a polarity of pixels in a preceding line.

11. The liquid crystal display as set forth in claim 9, wherein the source drive means includes source voltage switch means regulating the output of the source voltage by switching between predetermined two source voltages in accordance with a polarity of pixels in a preceding line.

12. The liquid crystal display as set forth in claim 1, wherein the active matrix drive has a frame frequency of 50 Hz or higher.

13. The liquid crystal display as set forth in claim 2, wherein the active matrix drive has a frame frequency of 50 Hz or higher.

14. The liquid crystal display as set forth in claim 3, wherein the active matrix drive has a frame frequency of 50 Hz or higher.

15. The liquid crystal display as set forth in claim 12, wherein the active matrix drive has a frame frequency of 100 Hz or higher.

16. The liquid crystal display as set forth in claim 13, wherein the active matrix drive has a frame frequency of 100 Hz or higher.

17. The liquid crystal display as set forth in claim 14, wherein the active matrix drive has a frame frequency of 100 Hz or higher.

21. The liquid crystal display as set forth in claim 2, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging in accordance with whether the pixels have identical or opposite polarities between frames when the gate drive means implements the gate 2 pulse drive.

22. The liquid crystal display as set forth in claim 3, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging in accordance with whether the pixels have identical or opposite polarities between frames when the gate drive means implements the gate 2 pulse drive.

25. The liquid crystal display as set forth in claim 2, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging from a polarity of the pixels in a preceding frame and a source output potential in precharging when the gate drive means implements the gate 2 pulse drive.

26. The liquid crystal display as set forth in claim 3, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging from a polarity of the pixels in a preceding frame and a source output potential in precharging when the gate drive means implements the gate 2 pulse drive.

31. The liquid crystal display as set forth in claim 1, further comprising multiple-frame-unit control means subjecting the polarity of the liquid crystal in the pixels to a reversal with multiple frames as a unit.

32. The liquid crystal display as set forth in claim 2, further comprising multiple-frame-unit control means subjecting the polarity of the liquid crystal in the pixels to a reversal with multiple frames as a unit.

33. The liquid crystal display as set forth in claim 3, further comprising multiple-frame-unit control means subjecting the polarity of the liquid crystal in the pixels to a reversal with multiple frames as a unit.

39. The liquid crystal display as set forth in claim 1, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

40. The liquid crystal display as set forth in claim 2, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

41. The liquid crystal display as set forth in claim 3, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

47. The liquid crystal display as set forth in claim 31, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

48. The liquid crystal display as set forth in claim 1, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

49. The liquid crystal display as set forth in claim 2, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

50. The liquid crystal display as set forth in claim 3, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

56. The liquid crystal display as set forth in claim 31, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

18. A liquid crystal display in which pixels are driven by active matrix drive, wherein:

a frame frequency is 100 Hz or higher; and

the display comprises interframe polarity control means controlling a polarity of liquid crystal in the pixels every so that a horizontal reversal for every two lines and a horizontal reversal for every line are alternately repeated for each frame.

19. The liquid crystal display as set forth in claim 18, further comprising:

a liquid crystal display screen composed of pixels arranged in a matrix;

gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in the pixels; and

source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels.

20. The liquid crystal display as set forth in claim 19, wherein:

the liquid crystal display screen is divided into two;

a first screen and a second screen;

the gate drive means is divided into two;

first gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in pixels in the first screen and second gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in pixels in the second screen; and

the source drive means is divided into two;

first source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels in the first screen and second source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels in the second screen.

23. The liquid crystal display as set forth in claim 19, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging in accordance with whether the pixels have identical or opposite polarities between frames when the gate drive means implements the gate 2 pulse drive.

24. The liquid crystal display as set forth in claim 20, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging in accordance with whether the pixels have identical or opposite polarities between frames when the gate drive means implements the gate 2 pulse drive.

27. The liquid crystal display as set forth in claim 19, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging from a polarity of the pixels in a preceding frame and a source output potential in precharging when the gate drive means implements the gate 2 pulse drive.

28. The liquid crystal display as set forth in claim 20, wherein:

the gate drive means implements a gate 2 pulse drive to subject the pixels to precharging and actual charging during a horizontal scan period for one line; and

the source drive means adjusts the source voltage in actual charging from a polarity of the pixels in a preceding frame and a source output potential in precharging when the gate drive means implements the gate 2 pulse drive.

34. The liquid crystal display as set forth in claim 18, further comprising multiple-frame-unit control means subjecting the polarity of the liquid crystal in the pixels to a reversal with multiple frames as a unit.

35. The liquid crystal display as set forth in claim 19, further comprising multiple-frame-unit control means subjecting the polarity of the liquid crystal in the pixels to a reversal with multiple frames as a unit.

36. The liquid crystal display as set forth in claim 20, further comprising multiple-frame-unit control means subjecting the polarity of the liquid crystal in the pixels to a reversal with multiple frames as a unit.

42. The liquid crystal display as set forth in claim 18, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

43. The liquid crystal display as set forth in claim 19, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

44. The liquid crystal display as set forth in claim 20, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

51. The liquid crystal display as set forth in claim 18, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

52. The liquid crystal display as set forth in claim 19, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

53. The liquid crystal display as set forth in claim 20, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

29. A liquid crystal display in which pixels are driven by active matrix drive, wherein:

a frame frequency is 100 Hz or higher; and

the display comprises polarity control means subjecting, for each frame, a polarity of liquid crystal in the pixels to a horizontal reversal once for a number of lines.

30. The liquid crystal display as set forth in claim 29, wherein the polarity control means implementing, for each frame, a horizontal reversal with different types of horizontal reversals once for a number of lines being mixed.

37. The liquid crystal display as set forth in claim 29, further comprising:

a liquid crystal display screen composed of pixels arranged in a matrix;

gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in the pixels; and

source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels.

38. The liquid crystal display as set forth in claim 37, wherein:

the liquid crystal display screen is divided into two;

a first screen and a second screen;

the gate drive means is divided into two;

first gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in pixels in the first screen and second gate drive means outputting a gate pulse to gate lines connected to gates of thin film transistors in pixels in the second screen; and

the source drive means is divided into two;

first source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels in the first screen and second source drive means outputting a source voltage to source lines connected to sources of the thin film transistors in the pixels in the second screen.

45. The liquid crystal display as set forth in claim 29, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

46. The liquid crystal display as set forth in claim 30, further comprising:

clock means multiplying a frame frequency of an input signal by k; and

frame interpolate means inserting an interpolated frame between frames.

54. The liquid crystal display as set forth in claim 29, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

55. The liquid crystal display as set forth in claim 30, further comprising overshoot drive means applying to the pixels a voltage corresponding to a higher grayscale level than a grayscale level represented by an input signal.

57. A method of driving a liquid crystal display, comprising the steps of:

driving pixels by active matrix drive; and

alternately repeating, for each frame, a first reversal pattern subjecting a polarity of liquid crystal in the pixels to a horizontal reversal once every m lines (m is 2 or a greater positive integer) and a second reversal pattern where the polarity reversal of lines in the first reversal pattern is shifted by n lines (n is a positive integer equal to a half or less of m).

58. A method of driving a liquid crystal display, comprising the steps of:

driving pixels by active matrix drive at a frame frequency of 100 Hz or higher; and

alternately repeating, for each frame, a horizontal reversal for every two lines and a horizontal reversal for every line with respect to a polarity of liquid crystal in the pixels.

59. A method of driving a liquid crystal display, comprising the steps of:

driving pixels by active matrix drive at a frame frequency of 100 Hz or higher; and

subjecting a polarity of liquid crystal in the pixels to a horizontal reversal for a number of lines for each frame.