Color OLED display with improved power efficiency

• US 7,230,594 B2
• Filed: 12/16/2002
• Issued: 06/12/2007
• Est. Priority Date: 12/16/2002
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Miller, Michael E., Cok, Ronald S., Arnold, Andrew D., Murdoch, Michael J.
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Nguyen; Jennifer T.
• Application Number:
  US10/320,195
• Publication Number:
  US 20040113875A1
• Time in Patent Office: 1,639 Days
• Field of Search: 345/613, 345/694, 345/695, 345/589, 345 82- 84, 345/77, 345/211, 345/76, 345 60- 63, 345/690, 313/504, 313/506, 315/169.1, 315/169.3
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]
• CPC Class Codes: H10K 59/352 the areas of the RGB subpixels being different
• CPC Class Codes: H10K 59/353 characterised by the geometrical arrangement of the RGB subpixels
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]

Abstract

An OLED display device includes an array of light emitting pixels, each pixel having three or more OLEDs for emitting different colors of light specifying a gamut and at least one additional OLED for emitting a color of light within the gamut, wherein the power efficiency of the additional OLED is higher than the luminance efficiency of at least one of the three or more OLEDs; and means for driving the OLEDs in the pixels to produce a given color and luminance at a reduced power usage.

Claims

1. An OLED display device, comprising:

a) an array of light emitting pixels, each pixel having three or more OLEDs for emitting different colors of light specifying a gamut and at least one additional OLED for emitting a color of light within the gamut, wherein the power efficiency of the additional OLED is higher than the power efficiency of at least one of the three or more OLEDs; and

b) means for driving the OLEDs in the pixels to produce a given color and luminance at a reduced power usage, wherein the means for driving produces in-gamut colors using a combination of light from the additional OLED and light from the three or more OLEDs;

wherein the three or more OLEDs and the additional OLED comprise the same light emitting material, the three or more OLEDs further comprise different color filters for producing the different colors of light specifying the gamut, and filtered light emitted by each of the three or more OLEDs has a narrower bandwidth than a bandwidth of light emitted by the additional OLED).

2. The OLED display device claimed in claim 1, wherein the three or more OLEDs emit red, green;

and blue colors of light.

3. The OLED display device claimed in claim 1, wherein the additional OLED emits white light.

4. The OLED display device claimed in claim 3, wherein the white light emitted by the additional OLED matches the white point of the display.

5. The OLED display device claimed in claim 1, wherein the OLEDs are of different sizes.

6. The OLED display device claimed in claim 1, wherein the additional OLED is larger than the three or more OLEDs.

7. The OLED display device in claim 1, wherein the OLED display device is a top emitting OLED device.

8. The OLED display device in claim 1, wherein the OLED display device is a bottom emitting OLED device.

9. The OLED display device in claim 1, wherein the OLED display device is an active matrix device.

10. The OLED display device in claim 1, wherein the OLED display device is a passive matrix device.

11. The OLED display device claimed in claim 1, wherein the means the driving reduces power usage to a minimum by maximizing the use of the additional OLEDs within each pixel.

12. The OLED display device claimed in claim 1, wherein the means for driving includes means for reducing the saturation of the display to increase brightness.

13. The OLED display device claimed in claim 1, having three additional OLEDs for emitting three colors of light within gamut.

14. The OLED display device claimed in claim 1, wherein the means for driving further comprises means for trading off power usage for image quality.

15. The OLED display device claimed in claim 14, wherein image quality includes one or more of color fringing, edge smoothness and sharpness.

16. The OLED display device claimed in claim 1, wherein the means for driving further comprises means for trading off power usage for display lifetime.

17. The OLED display device claimed in claim 1, wherein the color of light emitted by the additional OLED) is selected to improve the lifetime of the display.

18. The OLED display device claimed in claim 1, wherein the means for driving performs a conversion from an RGB signal to a device drive signal by calculation in real time.

19. The OLED display device claimed in claim 1, wherein the means for driving performs a conversion from an RGB signal to a device drive signal by reference to a look-up table.

20. The OLED display device claimed in claim 1, wherein each pixel further comprises one or more OLEDs for emitting a color of light that is the same color as the light emitted by the three or more OLEDs or the additional OLED(s).

21. The OLED display device claimed in claim 20, the one or more OLEDs emit light that is the same color as light emitted by one or more of the additional OLED(s).

22. The OLED display device claimed in claim 20, wherein the one or more OLEDs emit light that is the same color as light emitted by one or more of the three or more OLED(s).

23. The OLED display device claimed in claim 20, wherein the three or more OLEDs emit red, green, and blue colors of light, and wherein there are more green light emitting OLEDs than red or blue light emitting OLEDs.

24. The OLED display device claimed in claim 20, wherein the three or more OLEDs emit red, green and blue colors of light, and wherein there are more red light emitting OLEDs than blue light emitting OLEDs.

25. The OLED display device claimed in claim 1, wherein the three or more OLEDs emit red, green, and blue colors of light, and the additional OLED emits white light.

26. The OLED display device claimed in claim 25, wherein the peak luminance of the white additional OLED is set to a value from one half to one and a half times the peak luminance of the combined red, green and blue OLEDs.

27. The OLED display device claimed in claim 26, wherein the peak luminance of the white additional OLED is set to match the peak luminance of the combined red, green and blue OLEDs.

28. A method of reducing the power usage of an OLED display device, comprising the steps of:

a) providing a display having an array of light emitting pixels, each pixel having three or more OLEDs for emitting different colors of light specifying a gamut and at least one additional OLED for emitting a color of light within the gamut, wherein the power efficiency of the additional OLED is higher than the power efficiency of at least one of the three or more OLEDs; and

b) driving the OLEDs in the pixels to produce a given color and luminance at a reduced power usage, wherein the step of driving produces in-gamut colors using a combination of light from the additional OLED and light from the three or more OLEDs;

wherein the three or more OLEDs and the additional OLED comprise the same light emitting material, the three or more OLEDs further comprise different color filters for producing the different colors of light specifying the gamut, and filtered light emitted by each of the three or more OLEDs has a narrower bandwidth than a bandwidth of light emitted by the additional OLED.

29. The method claimed in claim 28, wherein the three or more OLEDs emit red, green, and blue colors of light.

30. The method claimed in claim 28, wherein the additional OLED emits white light.

31. The method claimed in claim 28, wherein the OLEDs are of different sizes.

32. The method claimed in claim 28, wherein the additional OLED is larger than the three or more OLEDs.

33. The method in claim 28, wherein the OLED display device is a top emitting OLED device.

34. The method in claim 28, wherein the OLED display device is a bottom emitting OLED device.

35. The method in claim 28, wherein the OLED display device is an active matrix device.

36. The method in claim 28, wherein the OLED display device is a passive matrix device.

37. The method claimed in claim 28, wherein the stop of driving reduces power usage to a minimum by maximizing the use of the additional OLEDs within each pixel.

38. The method claimed in claim 28, wherein the step of driving includes means for reducing the saturation of the display to increase brightness.

39. The method claimed in claim 28, wherein the display has three additional OLEDs for emitting three colors of light within gamut.

40. The method claimed in claim 28, wherein the step of driving further comprises trading off power usage for image quality.

41. The method claimed in claim 28, wherein the step of driving further comprises trading off power usage for display lifetime.

42. The method claimed in claim 28, wherein the color of light emitted by the additional OLED is selected to improve the lifetime of the display.

43. The method claimed in claim 28, wherein the step of driving includes performing a conversion from an RGB signal to a device drive signal by calculation in real time.

44. The method claimed in claim 28, wherein the step of driving includes performing a conversion from an RGB signal to a device drive signal by referencing a look-up table.

45. The method claimed in claim 28, wherein each pixel further comprises one or more OLEDs for emitting a color of light that is the same color as the light emitted by the three or more OLEDs or the additional OLED(s).

46. The method claimed in claim 45, the one or more OLEDs emit light that is the same color as light emitted by one or more of the additional OLED(s).

47. The method claimed in claim 45, wherein the one or more OLEDs emit light that is the same color as light emitted by one or more of the three or more OLED(s).

48. The method claimed in claim 45, wherein the three or more OLEDs emit red, green and blue colors of light, and wherein there are more green light emitting OLEDs than red or blue light emitting OLEDs.

49. The method claimed in claim 45, wherein the three or more OLEDs emit red, green, and blue colors of light, and wherein there are more red light emitting OLEDs than blue light emitting OLEDs.