Method for driving display device

• US 20050195175A1
• Filed: 03/05/2004
• Published: 09/08/2005
• Est. Priority Date: 03/05/2004
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Anderson, Daryl E.
• Granted Patent: US 7,439,965 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods

Abstract

A method is provided for reducing power consumption in a digital display including an array of pixels. The method includes reducing a switching frequency for driving the array of pixels and dividing the array of pixels into groups of a predefined size. A representative value of the input data for the group of pixels may be obtained using a weighting function and the group of pixels are driven to display the representative value.

Claims

1. A method for driving a digital display including an array of pixels in a first display mode and a second display mode, comprising:

driving the array of pixels at a first switching frequency when the first display mode is active;

driving the array of pixels at a second switching frequency when the second display mode is active; and

dividing the array of pixels into groups when the second display mode is active.

2. The method of claim 1, wherein when the second display mode is active, further including:

receiving image data for one group of pixels;

calculating a representative value of the image data; and

driving the one group of pixels to display the representative value of the image data.

3. The method of claim 2, wherein the second switching frequency is less than the first switching frequency.

4. The method of claim 2, wherein the representative value is obtained using a weighting function.

5. The method of claim 4, wherein the weighting function is based on the pixels in the one group.

6. The method of claim 5, wherein the weighting function is further based on pixels in an adjacent group.

7. The method of claim 4, wherein the representative value is an average of the image data.

8. The method of claim 2, wherein the calculating step includes calculating an average intensity level for each primary color in the image data.

9. The method of claim 8, further including converting the average intensity level for each primary color into a separate halftoned set of pixels.

10. The method of claim 9, further including using a mapping technique to distribute each halftoned set of pixels across the one group of pixels.

11. The method of claim 2, wherein the one group of pixels is a rectangular array.

12. The method of claim 11, wherein the rectangular array is selected from one of a 2×

2, 3×

3, 4×

4 and 5×

5 array.

13. The method of claim 1, wherein the digital display is capacitively driven.

14. The method of claim 13, wherein the digital display is selected from a liquid-crystal display device, a digital micro-mirror display device, and an interferometric display device.

15. The method of claim 1, wherein the first display mode is a high image quality display mode.

16. The method of claim 15, wherein the driving step comprises switching the pixels of the one group of pixels only once per frame when the second display mode is active.

17. The method of claim 15, wherein the driving step comprises switching the pixels of the one group of pixels only once for each primary color per frame when the second display mode is active.

36. The method of claim 15, wherein the driving step comprises switching the pixels of the one group of pixels only once for each primary color per frame.

18. A method for switching from a first display mode to a second display mode, comprising:

reducing a switching frequency used for driving a pixel display area in the first display mode;

dividing the pixel display area into groups of pixels;

receiving image data for one of the pixel groups;

calculating a representative value of the image data; and

driving the one group of pixels at the reduced switching frequency to display the representative value in the second display mode.

19. The method of claim 18, wherein the representative value is an average of the image data.

20. The method of claim 18, wherein the calculating step includes calculating an average intensity level for each primary color in the image data.

21. The method of claim 20, further including converting the average intensity level for each primary color into a separate halftoned set of pixels.

22. The method of claim 21, further including using a mapping technique to distribute each halftoned set of pixels across the one group of pixels.

23. The method of claim 18, wherein the one group of pixels is a rectangular array.

24. The method of claim 23, wherein the rectangular array is selected from one of a 2×

2, 3×

3, 4×

4 and 5×

5 array.

25. The method of claim 18, wherein the display device is capacitively driven.

26. The method of claim 25, wherein the display device is selected from a liquid-crystal display device, a digital micro-mirror display device, and an interferometric display device.

27. The method of claim 18, wherein the first display mode provides high image quality and the second display mode provides reduced power consumption.

28. The method of claim 27, wherein the driving step comprises switching the pixels of the one group of pixels only once per frame.

29. The method of claim 27, wherein the driving step comprises switching the pixels of the one group of pixels only once for each primary color per frame.

30. A method for reducing power consumption in a digital display including an array of pixels, comprising:

reducing a switching frequency for driving the array of pixels; and

dividing the array of pixels into groups of a predefined size.

31. The method of claim 30, further including:

receiving image data for one group of pixels;

calculating a weighted value of the image data; and

driving the one group of pixels to display the weighted value of the image data.

32. The method of claim 31, wherein the weighted value is an average of the image data and the calculating step further comprises converting the average into a halftoned set of pixel colors.

33. The method of claim 31, wherein the calculating step includes calculating an average intensity level for each primary color in the image data.

34. The method of claim 33, further including converting the average intensity level for each primary color into a separate halftoned set of pixels.

35. The method of claim 31, wherein the driving step comprises switching the pixels of the one group of pixels only once per frame.

37. The method of claim 30, wherein the digital display is capacitively driven.

38. A multi-mode display device including a display comprising an array of pixels, comprising:

means for driving the display in a first display mode that provides high image quality; and

means for driving the display in a second display mode that provides reduced power consumption and lower screen resolution.

39. The device of claim 38, wherein the means for driving the display in the second display mode comprises:

means for dividing the array of pixels into groups of pixels;

means for receiving image data for one of the pixel groups;

means for calculating a representative value of the image data; and

means for driving the one group of pixels to display the representative value of the image data.

40. The device of claim 39, wherein the representative value is an average of the image data and the calculating means converts the average of the image data into a halftoned set of pixel colors.

41. The device of claim 39, wherein the calculating means calculates an average intensity level for each primary color in the image data.

42. The device of claim 41, further including means for converting the average intensity level for each primary color into a separate halftoned set of pixels.

43. The device of claim 39, wherein the one group of pixels is a rectangular array.

44. The device of claim 38, wherein the display is capacitively driven.

45. The device of claim 44, wherein the display is selected from a liquid-crystal display device, a digital micro-mirror display device, and an interferometric display device.

46. The device of claim 38, further including means for switching between the first and second display modes.

47. The device of claim 38, wherein the means for driving the display in the second display mode switches the array of pixels only once per frame.

48. The device of claim 38, wherein the means for driving the display in the second display mode switches the array of pixels only once for each primary color per frame.

49. A multi-mode display device, comprising:

a display including a pixel display area; and

a controller configured to drive the display in accordance with first and second display modes, the first display mode providing high image quality and the second display mode providing reduced power consumption at lower image quality.

50. The device of claim 49, further including a memory containing image data, and wherein the controller operating in the second display mode is configured to:

receive image data for one group of pixels from the memory;

calculate a representative value of the image data; and

driving the one group of pixels to display the representative value of the image data.

51. The device of claim 50, wherein the representative value is an average of the image data and the controller operating in the second display mode is configured to convert the average into a halftoned set of pixel colors for each primary color.

52. The device of claim 49, wherein the display is capacitively driven.

53. The device of claim 49, further including a switch configured to placing the controller in the first display mode and the second display mode.

54. The device of claim 53, wherein the switch is user selectable.

55. The device of claim 49, wherein the controller is configured to suggest a display mode to a user based on at least one of battery power remaining and a type of image data to be displayed.