Display driving method and display apparatus utilizing the same

• US 20030016189A1
• Filed: 07/01/2002
• Published: 01/23/2003
• Est. Priority Date: 07/10/2001
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Sagano, Osamu, Ando, Muneki, Saito, Hiroshi, Abe, Naoto
• Granted Patent: US 6,985,141 B2
• Time in Patent Office: Days
• US Class Current: 345/55
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/22 using controlled light sources

Abstract

In order to obtain a satisfactory image by making a peak luminance of an image to be displayed large and suppressing an occurrence of unnecessary period, there is provided a display driving method for driving a display with a plurality of scanning wirings and a plurality of modulation wirings, comprising: a step of supplying a scan selection signal to a scanning wiring selected out of the plural scanning wirings for each horizontal scanning period; and a step of supplying a modulation signal modulated in accordance with image data to the plural modulation wirings for each horizontal scanning period, in which the selection period of the scan selection signal varies between at least two horizontal scanning periods in a vertical scanning period.

Claims

1. A display driving method for driving a display with a plurality of scanning wirings and a plurality of modulation wirings, comprising:

a step of supplying a scan selection signal to a scanning wiring selected out of the plural scanning wirings for each horizontal scanning period; and

a step of supplying a modulation signal modulated in accordance with image data to the plural modulation wirings for each horizontal scanning period,

wherein the selection period of the scan selection signal varies between at least two horizontal scanning periods in a vertical scanning period.

2. A driving method according to claim 1, wherein the selection period of the scan selection signal supplied to the scanning wiring in a horizontal scan period is determined so as to have a length according to the maximum duration of a modulation signal supplied to the modulation wirings in the horizontal scanning period.

3. A driving method according to claim 1, wherein the selection period of the scan selection signal supplied to the scanning wiring is set and the duration of a modulation signal supplied to the modulation wirings in a horizontal scanning period is determined in accordance with the set selection period.

4. A driving method according to claim 1, wherein a horizontal scanning period is set, and the selection period of the scan selection signal supplied to the scanning wiring in the horizontal scanning period as well as the duration of a modulation signal supplied to the modulation wirings in the horizontal scanning period are determined in accordance with the set horizontal scanning period.

5. A driving method according to claim 1, wherein the selection period of the scan selection signal supplied to a scanning wiring is determined in accordance with the maximum value of display luminance or adjusted image data of pixels on the selected scanning wirings.

6. A driving method according to claim 1, wherein an upper limit value or lower limit value, or both, are set for a horizontal scanning period and the horizontal scanning period is changed within a variable range set by the limit value(s).

7. A driving method according to claim 1, wherein the frame scanning period of a display image, which is determined by the sum of the horizontal scanning periods, is kept constant at least for over several frame scanning periods.

8. A driving method according to claim 1, wherein a lower limit value is set for the horizontal scanning period and, when the maximum duration of a modulation signal supplied to the modulation wirings in the horizontal scanning period does not reach the lower limit value, a blanking period is added to the modulation signal.

9. A driving method according to claim 1, wherein a lower limit value is set for the horizontal scanning period and, when the selection period of the scan selection signal supplied in the horizontal scanning period does not reach the lower limit value, a blanking period is added to the scan selection signal.

10. A driving method according to claim 1, wherein an upper limit value is set for the horizontal scanning period and the duration of a modulation signal is determined such that the maximum duration of the modulation signal supplied to the modulation wirings in the horizontal scanning period does not exceed the upper limit value.

11. A driving method according to claim 1, wherein the upper limit value is a value obtained by subtracting a given blanking period from the horizontal scanning period.

12. A driving method according to claim 1, wherein the length of the horizontal scanning period is controlled with the clock number as reference.

13. A driving method according to claim 1, wherein the image data includes luminance data of an image signal inputted and at least the duration of the modulation signal is modulated in accordance with the luminance data.

14. A driving method according to claim 1, wherein the image data includes luminance data and correction data of an image signal inputted and at least the duration of the modulation signal is determined in accordance with the luminance data and with the correction data.

15. A driving method according to claim 14, wherein the correction data is correction data for compensating the difference between a desired luminance and display luminance.

16. A driving method according to claim 14, wherein the correction data is correction data for compensating a change in voltage applied to a display device due to voltage drop taking place in the scanning wiring.

17. A driving method according to claim 1, wherein each horizontal scanning period set in accordance with luminance data and correction data of an image signal inputted receives gain adjustment and/or upper limit value adjustment.

18. A driving method according to claim 1, wherein gain adjustment is made on each horizontal scanning period set in accordance with luminance data and correction data of an image signal inputted so that a vertical scanning period of a display image, which is determined by the sum of the horizontal scanning periods, does not exceed a given value.

19. A driving method according to claim 1, wherein a horizontal scanning period of a pixel on a scanning wiring at the center of a screen of a display apparatus is longer than at least a horizontal scanning period of a pixel on another scanning wiring around the top or bottom of the screen.

20. A driving method according to claim 1, wherein the image data receives gain adjustment at a magnification set in accordance with each horizontal scanning period, and then is supplied to a modulation drive circuit.

47. A driving method according to claim 1, wherein the horizontal scanning period is determined by changing the frequency of a clock signal.

50. A driving method according to claim 2, wherein an upper limit value or lower limit value, or both, are set for a horizontal scanning period and the horizontal scanning period is changed within a variable range set by the limit value(s).

51. A driving method according to claim 2, wherein the frame scanning period of a display image, which is determined by the sum of the horizontal scanning periods, is kept constant at least for over several frame scanning periods.

52. A driving method according to claim 2, wherein a lower limit value is set for the horizontal scanning period and, when the maximum duration of a modulation signal supplied to the modulation wirings in the horizontal scanning period does not reach the lower limit value, a blanking period is added to the modulation signal.

53. A driving method according to claim 2, wherein a lower limit value is set for the horizontal scanning period and, when the selection period of the scan selection signal supplied in the horizontal scanning period does not reach the lower limit value, a blanking period is added to the scan selection signal.

54. A driving method according to claim 2, wherein an upper limit value is set for the horizontal scanning period and the duration of a modulation signal is determined such that the maximum duration of the modulation signal supplied to the modulation wirings in the horizontal scanning period does not exceed the upper limit value.

55. A driving method according to claim 2, wherein the image data includes luminance data and correction data of an image signal inputted and at least the duration of the modulation signal is determined in accordance with the luminance data and with the correction data.

56. A driving method according to claim 55, wherein the correction data is correction data for compensating the difference between a desired luminance and display luminance.

57. A driving method according to claim 55, wherein the correction data is correction data for compensating a change in voltage applied to a display device due to voltage drop taking place in the scanning wiring.

58. A driving method according to claim 3, wherein each horizontal scanning period set in accordance with luminance data and correction data of an image signal inputted receives gain adjustment and/or upper limit value adjustment.

59. A driving method according to claim 3, wherein gain adjustment is made on each horizontal scanning period set in accordance with luminance data and correction data of an image signal inputted so that a vertical scanning period of a display image, which is determined by the sum of the horizontal scanning periods, does not exceed a given value.

60. A driving method according to claim 3, wherein a horizontal scanning period of a pixel on a scanning wiring at the center of a screen of a display apparatus is longer than at least a horizontal scanning period of a pixel on another scanning wiring around the top or bottom of the screen.

61. A driving method according to claim 3, wherein the image data receives gain adjustment at a magnification set in accordance with each horizontal scanning period, and then is supplied to a modulation drive circuit.

62. A drive control method according to claim 4, wherein the horizontal scanning period is determined in accordance with the maximum image data and average image data of pixels of each row.

63. A drive control method according to claim 4, wherein image data is corrected in accordance with at least the maximum image data of each row or column, and image data stored in the memory is replaced by the adjusted image data.

64. A drive control method according to claim 4,

wherein a horizontal luminance level coefficient (Ah) is obtained from the maximum image data and average image data of pixels of each row,

wherein a minimum value (Am) of the luminance level coefficient is obtained from the horizontal luminance level coefficient (Ah) and an upper limit value (Al) of the coefficient, and

wherein image data of each pixel is corrected based on the minimum value (Am) of the luminance level coefficient.

65. A drive control method according to claim 4,

wherein a horizontal luminance level coefficient (Ah) is obtained from the maximum image data and average image data of pixels of each row,

wherein a vertical luminance level coefficient (Av) is obtained from the maximum image data and average image data of pixels of each column,

wherein a minimum value (Am) of the luminance level coefficient is obtained from the horizontal luminance level coefficient (Ah), the vertical luminance level coefficient (Av), and an upper limit value (Al) of the coefficient, and

wherein image data of each pixel is corrected based on the minimum value (Am) of the luminance level coefficient.

21. A display apparatus comprising:

a display having a plurality of scanning wirings and a plurality of modulation wirings;

a scan drive circuit for supplying a scan selection signal to a scanning wiring selected out of the plural scanning wirings for each horizontal scanning period; and

a modulation drive circuit for supplying a modulation signal modulated in accordance with image data to the plural modulation wirings for each horizontal scanning period,

wherein the apparatus further comprises a drive control circuit for controlling the scan drive circuit such that the selection period of the scan selection signal varies between at least two horizontal scanning periods in a vertical scanning period.

22. A display apparatus according to claim 21, wherein the drive control circuit detects from an image signal inputted the maximum value of luminance data in each horizontal scanning period, and sets the selection period of the scan selection signal in accordance with the maximum value.

23. A display apparatus according to claim 21, wherein the drive control circuit detects from an image signal inputted the maximum value of adjusted image data obtained by correcting luminance data in each horizontal scanning period, and sets the selection period of the scan selection signal in accordance with the maximum value.

24. A display apparatus according to claim 21, wherein the drive control circuit determines the selection period of the scan selection signal and the duration of the modulation signal in accordance with a horizontal scanning period set within a variable range in which a horizontal scanning period is allowed to change.

25. A display apparatus according to claim 21,

wherein the drive control circuit detects from an image signal inputted the maximum value of adjusted image data obtained by correcting luminance data in each horizontal scanning period, and sets the selection period of the scan selection signal in accordance with the maximum value, and

wherein at least one horizontal scanning period is adjusted such that a vertical scanning period of a display image, which is determined by the sum of the horizontal scanning periods, reaches a given value.

26. A display apparatus according to claim 25, wherein the apparatus further comprises a gain adjuster and/or limiter for the adjustment of at least one horizontal scanning period.

27. A display apparatus according to claim 21, wherein the drive control circuit is provided with a frame memory for storing one frame of adjusted image data obtained from an inputted image signal by correcting luminance data in each horizontal scanning period in order to adjust horizontal scanning periods.

28. A display apparatus according to claim 27, wherein the frame memory has two frame memories and is controlled such that data is read out of one of the frame memories while data is written in the other.

29. A display apparatus according to claim 27, wherein adjusted image data of one horizontal scanning period are read out of the frame memory in layers in parallel, and the layers of adjusted image data are inputted to a plurality of shift registers provided for each layer.

30. A display apparatus according to claim 21, wherein the drive control circuit determines the selection period of the scan selection signal and the duration of the modulation signal in accordance with each of set horizontal scanning periods.

31. A display apparatus according to claim 21, wherein the vertical scanning period of a display image, which is determined by the sum of the horizontal scanning periods, is kept constant at least for over several vertical scanning periods.

32. A display apparatus according to claim 21, wherein a horizontal scanning period of a pixel on a scanning wiring at the center of a screen of the display is longer than at least a horizontal scanning period of a pixel on another scanning wiring around the top or bottom of the screen.

33. A display apparatus according to claim 21, wherein the drive control circuit adjusts the image data in accordance with a set horizontal scanning period.

34. A display apparatus according to claim 33, wherein, after the image data is adjusted, the modulation drive circuit generates the modulation signal from the image data.

35. A display apparatus according to claim 21, wherein the display is a self-luminous display.

36. A display apparatus according to claim 21, wherein the display has a plurality of display devices including an electron-emitting device.

37. A drive control method for use in the display apparatus of claim 21, wherein a timing signal for determining the horizontal scanning period is generated.

38. A drive control method according to claim 37, wherein the timing signal is generated in accordance with the maximum image data in a given scanning period.

39. A drive control method according to claim 38, wherein the image data includes luminance data and correction data.

40. A drive control method according to claim 37, wherein the horizontal scanning period is determined in accordance with the maximum image data and average image data of pixels of each row.

41. A drive control method according to claim 37, wherein image data is corrected in accordance with at least the maximum image data of each row or column, and image data stored in the memory is replaced by the adjusted image data.

42. A drive control method according to claim 37,

wherein a horizontal luminance level coefficient (Ah) is obtained from the maximum image data and average image data of pixels of each row,

wherein a minimum value (Am) of the luminance level coefficient is obtained from the horizontal luminance level coefficient (Ah) and an upper limit value (Al) of the coefficient, and

wherein image data of each pixel is corrected based on the minimum value (Am) of the luminance level coefficient.

43. A drive control method according to claim 37,

wherein a horizontal luminance level coefficient (Ah) is obtained from the maximum image data and average image data of pixels of each row,

wherein a vertical luminance level coefficient (Av) is obtained from the maximum image data and average image data of pixels of each column,

wherein a minimum value (Am) of the luminance level coefficient is obtained from the horizontal luminance level coefficient (Ah), the vertical luminance level coefficient (Av), and an upper limit value (Al) of the coefficient, and

wherein image data of each pixel is corrected based on the minimum value (Am) of the luminance level coefficient.

44. A program for carrying out a drive control method of claim 37.

45. An integrated circuit for carrying out a drive control method of claim 37.

46. A design property for designing an integrated circuit to carry out a drive control method of claim 37.

48. Display apparatus according to claim 21, wherein the horizontal scanning period is determined by changing the frequency of a clock signal.

49. A drive control method according to claim 37, wherein the horizontal scanning period is determined by changing the frequency of a clock signal.