Illumination intensity control in electroluminescent display

• US 6,541,921 B1
• Filed: 10/17/2001
• Issued: 04/01/2003
• Est. Priority Date: 10/17/2001
• Status: Expired due to Term

• Current Assignee: Sg Gaming, Inc. (Light & Wonder Incorporated)
• Original Assignee: Sierra Design Group (Light & Wonder Incorporated)
• Inventors: Prokop, Alexander, Bertram, William Keith, Hicksted, Richard Louis, Luciano, Robert Anthony Jr.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Vu, Jimmy T.
• Application Number:
  US10/045,504
• Time in Patent Office: 531 Days
• Field of Search: 315/169.1, 315/169.3, 313/309, 313/310, 313/495, 313/496, 313/351, 445/51, 445/36, 257/10
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/12 using electroluminescent elements
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: H05B 44/00 Circuit arrangements for operating electroluminescent light sources for operating light emitting diodes H05B45/00
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A controller for controlling the intensity of an electroluminescent display is disclosed. The controller controls a number of skipped cycles in a cycle set of an applied waveform to the electroluminescent display to vary the average duty cycle, and thereby adjust the intensity of the electroluminescent display. The controller is further configured to adjust the intensity of individual channels within the electroluminescent display to provide compensation for display aging, color variation, as well as for varying intensity for various operating modes.

Claims

1. An intensity controller for an electroluminescent display having a first electrode and a second electrode, the intensity controller comprising:

a processor;

a waveform generator controlled by the processor configured to generate a waveform signal;

a drive circuit controlled by the processor and coupled to said waveform generator, said drive circuit configured to receive said waveform signal from said waveform generator and generate a substantially sinusoidal waveform across said first and second electrode to illuminate the electroluminescent display, said sinusoidal waveform further comprising a cycle set having a plurality n of cycles, and

an intensity controller executed by said processor, said intensity controller configured to adjust an illumination intensity of said electroluminescent display by adding or removing at least one skip cycle in said cycle set.

2. The intensity controller of claim 1, wherein a number of non-skip cycles to the number of cycles in said cycle set establishes an overall duty cycle for said cycle set.

3. The intensity controller of claim 1, wherein said skip cycle is a substantially cancelled cycle.

4. The intensity controller of claim 1, further comprising an aging controller executed by said processor configured to:

determine a change in impedance of said electroluminescent display; and

adjust said illumination intensity if said change,in impedance exceeds a threshold value by removing at least one skip cycle in said cycle set.

5. The intensity controller of claim 1, further comprising an aging controller executed by said processor configured to:

determine a change in capacitance of said electroluminescent display; and

adjust said illumination intensity if said change in capacitance exceeds a threshold value by removing at least one skip cycle in said cycle set.

6. The intensity controller of claim 1, wherein said cycle set includes an initial number m of skipped cycles, said intensity controller further comprising a color compensation controller executed by said processor configured to color adjust said illumination intensity by adding or removing at least one skip cycle in said cycle set.

7. The intensity controller of claim 6, wherein said electroluminescent display comprises a color filter, said color compensation controller configured to adjust said illumination intensity by removing at least one skip cycle in said cycle set.

8. The intensity controller of claim 1 further comprising a power supply configured to provide a DC voltage and a ground, said power supply coupled to said waveform generator, said waveform generator further configured to generate a half-wave waveform from said DC voltage, said drive circuit configured to apply said half-wave waveform in phase during a skip cycle.

9. The intensity controller of claim 8, wherein said drive circuit is further configured to apply said half-wave waveform out of phase during non-skip cycles.

10. The intensity controller of claim 8, wherein said drive circuit is further configured to apply said half-wave waveform in phase for the entire cycle set to cancel illumination of said electroluminescent display during an off state.

11. The intensity controller of claim 9, wherein each cycle within said cycle set comprises a first and second half, said drive circuit further configured to:

apply said half-wave waveform out of phase by applying the half-wave waveform to the first electrode and connect said second electrode to said ground during the first half of a designated cycle; and

apply the half-wave waveform to the second electrode and connect said first electrode to said ground during the second half of said designated cycle.

12. The intensity controller of claim 8, wherein each cycle within said cycle set comprises a first and second half, said drive circuit further configured to:

connect said first electrode and said second electrode to said ground during said first half of a designated cycle; and

apply said half-wave waveform in phase by applying the half-wave waveform to the first electrode and to the second electrode during said second half of said designated cycle.

13. The intensity controller of claim 1, wherein electroluminescent display further comprises an illumination threshold, said sinusoidal waveform further comprising a voltage amplitude exceeding said illumination threshold of said electroluminescent display.

14. The intensity controller of claim 1, wherein said sinusoidal waveform comprises a frequency of 1000 Hz and said cycle set comprises 16 cycles.

26. The intensity controller of claim 8, wherein said drive circuit is further configured to apply said half-wave waveform in phase for the entire cycle set to designated off state channels of said electroluminescent display.

15. An intensity controller for an electroluminescent display having a plurality of channels, each channel having a first electrode and sharing a common second electrode, the intensity controller comprising:

a processor;

a waveform generator controlled by the processor configured to generate a

waveform signal;

a multiple-channel drive circuit controlled by the processor and coupled to said waveform generator, said drive circuit configured to receive said waveform signal from said waveform generator and generate a substantially sinusoidal waveform across each said first and second electrode to illuminate each respective channel of the electroluminescent display independently, said sinusoidal waveform further comprising a cycle set having a plurality n of cycles, and

an intensity controller executed by said processor, said intensity controller configured to adjust an illumination intensity of each said channel of said electroluminescent display by adding or removing at least one skip cycle in said cycle set applied to said respective channels.

16. The intensity controller of claim 15, wherein a number of non-skip cycles to the number of cycles in said cycle set establishes an overall duty cycle for said cycle set.

17. The intensity controller of claim 15, wherein said skip cycle is a substantially cancelled cycle.

18. The intensity controller of claim 17, further comprising an aging controller executed by said processor configured to:

determine a change in impedance of each said channel in said

electroluminescent display; and

adjust said illumination intensity of a channel if said change in impedance exceeds a threshold value by removing at least one skip cycle in said cycle set applied to said channel.

19. The intensity controller of claim 17, further comprising an aging controller executed by said processor configured to:

determine a change in capacitance of each said channel of said electroluminescent display; and

adjust said illumination intensity of a channel if said change in capacitance exceeds a threshold value by removing at least one skip cycle in said cycle set applied to said channel.

20. The intensity controller of claim 15, wherein said cycle set includes an initial number m of skipped cycles, said intensity controller further comprising a color compensation controller executed by said processor configured to color adjust said illumination intensity by adding or removing at least one skip cycle in said cycle set.

21. The intensity controller of claim 20, wherein at least one of said channel of said electroluminescent display comprises a color filter, said color compensation controller configured to adjust said illumination intensity of said channel by removing at least one skip cycle in said cycle set.

22. The intensity controller of claim 20, wherein said color compensation controller further comprises a lookup table for each channel, said lookup table defining initial operating parameters for each said channel, said color compensation controller configured to adjust said illumination intensity by adding or removing at least one skip cycle in said cycle set in accordance with said initial operating parameters.

23. The intensity controller of claim 22, further comprising an aging controller executed by said processor configured to:

determine a change in capacitance of each said channel of said

electroluminescent display; and

adjust said illumination intensity of a channel if said change in capacitance exceeds a threshold value by removing at least one skip cycle in said cycle set applied to said channel.

24. The intensity controller of claim 15 further comprising a power supply configured to provide a DC voltage and a ground, said power supply coupled to said waveform generator, said waveform generator further configured to generate a half-wave waveform from said DC voltage, said drive circuit configured to apply said half-wave waveform in phase during a skip cycle.

25. The intensity controller of claim 24, wherein said drive circuit is further configured to apply said half-wave waveform out of phase during non-skip cycles.

27. The intensity controller of claim 25, wherein each cycle within said cycle set comprises a first and second half, said drive circuit further configured to:

apply said half-wave waveform out of phase by applying the half-wave waveform to the first electrode and connect said second electrode to said ground during the first half of a designated cycle for each said channel; and

apply the half-wave waveform to the second electrode and connect said first electrode to said ground during the second half of said designated cycle for each said channel.

28. The intensity controller of claim 24, wherein each cycle within said cycle set comprises a first and second half, said drive circuit further configured to:

connect said first electrode and said second electrode to said ground during said first half of a designated cycle for each said channel; and

apply said half-wave waveform in phase by applying the half-wave waveform to the first electrode and to the second electrode during said second half of said designated cycle for each said channel.

29. The intensity controller of claim 15, wherein electroluminescent display further comprises an illumination threshold, said sinusoidal waveform further comprising a voltage amplitude exceeding said illumination threshold of said electroluminescent display.

30. The intensity controller of claim 15, wherein said sinusoidal waveform comprises a frequency of 1000 Hz and said cycle set comprises 16 cycles.

31. A device operable by a user comprising:

an electroluminescent display having a first electrode, a second electrode

and a ground; and

an intensity controller for an electroluminescent display having a first

electrode, a second electrode and a ground, the intensity controller comprising;

a processor;

a waveform generator controlled by the processor configured to

generate a waveform signal;

a drive circuit controlled by the processor and coupled to said waveform generator, said drive circuit configured to receive said waveform signal from said waveform generator and generate a substantially sinusoidal waveform across said first and second electrode to illuminate the electroluminescent display, said sinusoidal waveform further comprising a cycle set having a plurality n of cycles, and

an intensity controller executed by said processor, said intensity controller configured to adjust an illumination intensity of said electroluminescent display by adding or removing at least one skip cycle in said cycle set.

32. The device of claim 31, wherein a number of non-skip cycles to the number of cycles in said cycle set establishes an overall duty cycle for said cycle set.

33. The device of claim 31, wherein said-skip cycle is a substantially cancelled cycle.

34. The device of claim 31, further comprising an aging controller executed by said processor configured to:

determine a change in impedance of said electroluminescent display; and

adjust said illumination intensity if said change in impedance exceeds a threshold value by removing at least one skip cycle in said cycle set.

35. The device of claim 31, further comprising an aging controller executed by said processor configured to:

determine a change in capacitance of said electroluminescent display; and

adjust said illumination intensity if said change in capacitance exceeds a threshold value by removing at least one skip cycle in said cycle set.

36. The device of claim 31, wherein said cycle set includes an initial number m of skipped cycles, said intensity controller further comprising a color compensation controller executed by said processor configured to color adjust said illumination intensity by adding or removing at least one skip cycle in said cycle set.

37. The device of claim 36, wherein said electroluminescent display comprises a color filter, said color compensation controller configured to adjust said illumination intensity by removing at least one skip cycle in said cycle set.

38. The device of claim 31 further comprising a power supply configured to provide a DC voltage and a ground, said power supply coupled to said waveform generator, said waveform generator further configured to generate a half-wave waveform from said DC voltage, said drive circuit configured to apply said half-wave waveform in phase during a skip cycle.

39. The device of claim 38, wherein said drive circuit is further configured to apply said half-wave waveform out of phase during non-skip cycles.

40. The device of claim 38, wherein said drive circuit is further configured to apply said half-wave waveform in phase for the entire cycle set to cancel illumination of said electroluminescent display during an off state.

41. The device of claim 39, wherein each cycle within said cycle set comprises a first and second half, said drive circuit further configured to:

apply said half-wave waveform out of phase by applying the half-wave waveform to the first electrode and connect said second electrode to said ground during the first half of a designated cycle, and

apply the half-wave waveform to the second electrode and connect said first electrode to said ground during the second half of said designated cycle.

42. The device of claim 38, wherein each cycle within said cycle set comprises a first and second half, said drive circuit further configured to:

connect said first electrode and said second electrode to said ground during said first half of a designated cycle; and

apply said half-wave waveform in phase by applying the half-wave waveform to the first electrode and to the second electrode during said second half of said designated cycle.

43. The device of claim 31, wherein electroluminescent display further comprises an illumination threshold, said sinusoidal waveform further comprising a voltage amplitude exceeding said illumination threshold of said electroluminescent display.

44. The device of claim 31, wherein said sinusoidal waveform comprises a frequency of 1000 Hz and said cycle set comprises 16 cycles.

45. The device of claim 31, wherein said device comprises a gaming device having a game of chance playable by said user, said electroluminescent display adjusted according to operation of said game of chance.

46. A method for controlling the illumination intensity of an electroluminescent display having a first electrode, a second electrode, said method comprising:

generating a substantially sinusoidal waveform;

applying said sinusoidal waveform across said first and second electrode to illuminate the electroluminescent display, said sinusoidal waveform further comprising a cycle set having a plurality n of cycles, and adjusting an illumination intensity of said electroluminescent display by adding or removing at least one skip cycle in said cycle set.

47. The method of claim 46, wherein a number of non-skip cycles to the number of cycles in said cycle set establishes an overall duty cycle for said cycle set.

48. The method of claim 46, wherein said skip cycle is a substantially cancelled cycle.

49. The method of claim 46, further comprising:

determining a change in impedance of said electroluminescent display; and

adjusting said illumination intensity if said change in impedance exceeds a threshold value by removing at least one skip cycle in said cycle set.

50. The method of claim 46, further comprising:

determining a change in capacitance of said electroluminescent display; and

adjusting said illumination intensity if said change in capacitance exceeds a threshold value by removing at least one skip cycle in said cycle set.

51. The method of claim 46, wherein said cycle set includes an initial number m of skipped cycles, said method further comprising adjusting said illumination intensity by adding or removing at least one skip cycle in said cycle set.

52. The method of claim 51, wherein said electroluminescent display comprises a color filter, said method further comprising adjusting said illumination intensity by removing at least one skip cycle in said cycle set.

53. The method of claim 46, wherein said generating said sinusoidal waveform further comprises generating a half-wave waveform from a power supply providing a DC voltage and a ground, said method further comprising applying said half-wave waveform in phase during a skip cycle.

54. The method of claim 53, further comprising applying said half-wave waveform out of phase during non-skip cycles.

55. The method of claim 53, further comprising applying said half-wave waveform in phase for the entire cycle set to cancel illumination of said electroluminescent display during an off state.

56. The method of claim 54, wherein each cycle within said cycle set comprises a first and second half, said applying said half-wave waveform out of phase comprising:

applying the half-wave waveform to the first electrode and connecting said second electrode to said ground during the first half of a designated cycle; and

applying the half-wave waveform to the second electrode and connecting said first electrode to said ground during the second half of said designated cycle.

57. The method of claim 53, wherein each cycle within said cycle set comprises a first and second half, said applying said half-wave waveform in phase comprising:

connecting said first electrode and said second electrode to said ground during said first half of a designated cycle; and

applying said half-wave waveform in phase by applying the half-wave waveform to the first electrode and to the second electrode during said second half of said designated cycle.

58. The method of claim 46, wherein electroluminescent display further comprises an illumination threshold, said sinusoidal waveform further comprising a voltage amplitude exceeding said illumination threshold of said electroluminescent display.

59. The method of claim 46, wherein said sinusoidal waveform comprises a frequency of 1000 Hz and said cycle set comprises 16 cycles.

60. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform a method for controlling the illumination intensity of an electroluminescent display having a first electrode, a second electrode, said method comprising:

generating a substantially sinusoidal waveform;

applying said sinusoidal waveform across said first and second electrode to illuminate the electroluminescent display, said sinusoidal waveform further comprising a cycle set having a plurality n of cycles, and

adjusting an illumination intensity of said electroluminescent display by adding or removing at least one skip cycle in said cycle set.

61. The program storage device of claim 60, wherein a number of non-skip cycles to the number of cycles in said cycle set establishes an overall duty cycle for said cycle set.

62. The program storage device of claim 60, wherein said skip cycle is a substantially cancelled cycle.

63. The program storage device of claim 60, said method further comprising:

determining a change in impedance of said electroluminescent display; and

adjusting said illumination intensity if said change in impedance exceeds a threshold value by removing at least one skip cycle in said cycle set.

64. The program storage device of claim 60, said method further comprising:

determining a change in capacitance of said electroluminescent display; and

adjusting said illumination intensity if said change in capacitance exceeds a threshold value by removing at least one skip cycle in said cycle set.

65. The program storage device of claim 60, wherein said cycle set includes an initial number m of skipped cycles, said method further comprising adjusting said illumination intensity by adding or removing at least one skip cycle in said cycle set.

66. The program storage device of claim 65, wherein said electroluminescent display comprises a color filter, said method further comprising adjusting said illumination intensity by removing at least one skip cycle in said cycle set.

67. The program storage device of claim 60, wherein said generating said sinusoidal waveform further comprises generating a half-wave waveform from a power supply providing a DC voltage and a ground, said method further comprising applying said half-wave waveform in phase during a skip cycle.

68. The program storage device of claim 67, further comprising applying said half-wave waveform out of phase during non-skip cycles.

69. The program storage device of claim 67, further comprising applying said half-wave waveform in phase for the entire cycle set to cancel illumination of said electroluminescent display during an off state.

70. The program storage device of claim 68, wherein each cycle within said cycle set comprises a first and second half, said applying said half-wave waveform out of phase comprising:

applying the half-wave waveform to the first electrode and connecting said second electrode to said ground during the first half of a designated cycle; and

applying the half-wave waveform to the second electrode and connecting said first electrode to said ground during the second half of said designated cycle.

71. The program storage device of claim 67, wherein each cycle within said cycle set comprises a first and second half, said applying said half-wave waveform in phase comprising:

connecting said first electrode and said second electrode to said ground during said first half of a designated cycle; and

applying said half-wave waveform in phase by applying the half-wave waveform to the first electrode and to the second electrode during said second half of said designated cycle.

72. The program storage device of claim 60, wherein electroluminescent display further comprises an illumination threshold, said sinusoidal waveform further comprising a voltage amplitude exceeding said illumination threshold of said electroluminescent display.

73. The program storage device of claim 60, wherein said sinusoidal waveform comprises a frequency of 1000 Hz and said cycle set comprises 16 cycles.