Display calibration systems and related methods

• US 20110063268A1
• Filed: 08/05/2010
• Published: 03/17/2011
• Est. Priority Date: 09/05/2008
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Ketra, Inc. (Lutron Electronics)
• Inventors: Knapp, David J.
• Granted Patent: US 9,276,766 B2
• Time in Patent Office: Days
• US Class Current: 345/207
• CPC Class Codes: H04L 12/42 Loop networks

Abstract

Display calibration systems and related methods are disclosed that use photo-sensitivity of LEDs to correct for variations between LEDs during initial production and over lifetime for display systems. The display devices include arrays of LEDs and use photo-sensitivity of the LEDs to correct for variations between LEDs. Such LED arrays can produce images directly as in LED billboards and sports arena scoreboards, and smaller Organic LED (OLED) displays, or can produce the backlight for LCD screens for instance. Variations in LED brightness and color can be compensated for in order for such a display to have uniform color and brightness. This compensation is performed in the embodiments disclosed by measuring the signal induced on each LED by uniform incident light as a measurement of the photo-sensitivity of the LEDs.

Claims

1. A display device, comprising:

an array of LEDs; and

control circuitry configured to use photo-sensitivity of one or more of the LEDs to adjust output power from one or more of the LEDs.

2. The display device as recited in claim 1, wherein the display device is configured to receive light from a light source when photo-sensitivity is measured.

3. The display device as recited in claim 2, wherein the display device is configured to receive sunlight when photo-sensitivity is measured.

4. The display device as recited in claim 2, wherein the display device is configured to receive a fixed spectrum matching a peak emission wavelength of one or more of the LEDs when photo-sensitivity is measured.

5. The display device as recited in claim 1, wherein photo-sensitivity is determined in part using an open circuit voltage measurement.

6. The display device as recited in claim 1, wherein photo-sensitivity is determined in part using a short circuit current measurement.

7. The display device as recited in claim 1, wherein the output power from one or more of the LEDs is adjusted using correction coefficients configured to adjust current applied to one or more of the LEDs.

8. The display device as recited in claim 7, wherein the correction coefficients are configured to compensate for intensity of light produced by the adjusted LEDs.

9. The display device as recited in claim 7, wherein the correction coefficients are configured to compensate for intensity of light and wavelength produced by the adjusted LEDs.

10. The display device as recited in claim 1, wherein the array of LEDs comprises organic LEDs.

11. The display device as recited in claim 1, wherein the array of LEDs comprises inorganic LEDs.

12. The display device as recited in claim 1, wherein the array of LEDs is configured to produce a backlight.

13. The display device as recited in claim 12, wherein the backlight is configured to be modulated on a pixel by pixel basis to produce images.

14. The display device as recited in claim 13, wherein the backlight is configured to be modulated by liquid crystal.

15. The display device as recited in claim 12, further comprising a color filter positioned in front of the backlight provided by the array of LEDs and a liquid crystal array positioned in front of the color filter.

16. The display device as recited in claim 15, further comprising a diffuser and a polarizer positioned between the color filter and the backlight provided by the array of LEDs and further comprising a polarizer in front of the liquid crystal array.

17. The display device as recited in claim 12, further comprising a liquid crystal array positioned in front of the backlight provided by the array of LEDs without an intervening color filter.

18. The display device as recited in claim 17, further comprising a diffuser and a polarizer positioned between the liquid crystal array and the backlight provided by the array of LEDs and further comprising a polarizer in front of the liquid crystal array.

19. The display device as recited in claim 1, wherein the display device is configured to operate within a billboard.

20. The display device as recited in claim 1, wherein the display device is configured to operate within a direct emission display.

21. The display device as recited in claim 1, wherein the display device is configured to operate within a projector.

22. The display device as recited in claim 7, further comprising a memory configured to store the correction coefficients.

23. The display device as recited in claim 22, wherein the correction coefficients were generated during manufacturing of the display device.

24. The display device as recited in claim 22, wherein the control circuitry is configured compare current photo-sensitivity with previously determined photo-sensitivity to generate the correction coefficients.

25. The display device as recited in claim 24, wherein the previously determined photo-sensitivity was determined during manufacturing of the display device.

26. A method for operating a display device, comprising:

providing an array of LEDs within a display device;

measuring photo-sensitivity of one or more of the LEDs; and

adjusting output power from one or more of the LEDs based upon the measured photo-sensitivity.

27. The method as recited in claim 26, wherein the measuring step is conducted using a light source to illuminate the display device.

28. The method as recited in claim 27, further comprising utilizing sunlight as the light source.

29. The method as recited in claim 27, further comprising utilizing a fixed spectrum matching a peak emission wavelength of the LEDs as the light source.

30. The method as recited in claim 26, wherein the measuring step comprises utilizing an open circuit voltage measurement to in part determine the photo-sensitivity.

31. The method as recited in claim 26, wherein the measuring step comprises utilizing a short circuit current measurement to in part determine the photo-sensitivity.

32. The method as recited in claim 26, wherein the adjusting step comprises adjusting the output power using correction coefficients to adjust current applied to one or more of the LEDs.

33. The method as recited in claim 32, further comprising using the correction coefficients to compensate for intensity of light produced by the LEDs.

34. The method as recited in claim 32, further comprising using the correction coefficients to compensate for intensity of light and wavelength produced by the LEDs.

35. The method as recited in claim 26, wherein the array of LEDs comprises organic LEDs.

36. The method as recited in claim 26, wherein the array of LEDs comprises inorganic LEDs.

37. The method as recited in claim 26, further comprising utilizing the array of LEDs to produce a backlight.

38. The method as recited in claim 37, further comprising modulating the backlight on a pixel by pixel basis to produce images.

39. The method as recited in claim 38, wherein the modulating step comprises modulating the backlight by liquid crystal.

40. The method as recited in claim 37, further comprising color filtering light from the backlight and then modulating the color filtered light using a liquid crystal array.

41. The method as recited in claim 40, further comprising diffusing and polarizing the light from the backlight prior to the color filtering step.

42. The method as recited in claim 37, further comprising modulating light from the backlight using a liquid crystal array without an intervening color filtering.

43. The method as recited in claim 42, further comprising diffusing and polarizing the light from the backlight prior to the modulating step.

44. The method as recited in claim 26, further comprising operating the display device as part of a billboard.

45. The method as recited in claim 26, further comprising operating the display device as part of a direct emission display.

46. The method as recited in claim 26, further comprising operating the display device as part of a projector.

47. The method as recited in claim 32, further comprising storing the correction coefficients within a memory within the display device.

48. The method as recited in claim 47, wherein the correction coefficients were generated during manufacturing of the display device.

49. The method as recited in claim 47, further comprising comparing current photo-sensitivity measurements from the measuring step with previously determined measurements to generate the correction coefficients.

50. The method as recited in claim 49, wherein the previously determined measurements were conducted during manufacturing of the display device.