Light-emitting devices

• US 20040021423A1
• Filed: 06/18/2003
• Published: 02/05/2004
• Est. Priority Date: 06/23/2000
• Status: Active Grant

• Current Assignee: IPIFS Guarantee Corp.
• Original Assignee: IPIFS Guarantee Corp.
• Inventors: Lacey, David, Altrip, John, Jongman, Jan
• Granted Patent: US 6,801,000 B2
• Time in Patent Office: Days
• US Class Current: 315/169.1
• 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 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 59/17 Passive-matrix OLED displays
• 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 59/805 Electrodes

Abstract

A light-emitting device comprising: a first electroluminescent element for emitting light of a first colour when energised; and a second electroluminescent element for emitting light of a second colour when energised, the first electroluminescent element having an active lifetime which is greater than that of the second electroluminescent element; characterised in that the second element is configured to operate at a lower brightness than the first element.

Claims

1. A light-emitting device comprising:

a first electroluminescent element for emitting light of a first colour when energised; and

a second electroluminescent element for emitting light of a second colour when energised, the first electroluminescent element having an active lifetime which is greater than that of the second electroluminescent element;

characterised in that the second element is configured to operate at a lower brightness than the first element.

2. A light-emitting device according to claim 1, in which the first or second electroluminescent elements comprise organic light emissive material.

3. A light-emitting device according to claim 2, in which the organic light emissive material is polymeric.

4. A light-emitting device according to any one of claims 1 to 3, in which the first and second electroluminescent elements are energised by a common potential.

5. A light-emitting device according to claim 4, in which the common potential is applied through an electrode common to both elements.

6. A light-emitting device according to claim 5, in which the common potential is applied between an anode and a cathode common to both elements.

7. A light-emitting device according to any one of claims 1 to 6, in which the first and second electroluminescent elements are energised by different potentials.

8. A light-emitting device according to claim 7, in which the second electroluminescent element is energised at a higher potential than the first electroluminescent element.

9. A light-emitting device according to claim 4,5,7 or 8, in which the potential applied to one or both of the electroluminescent elements is pulsed.

10. A light-emitting device according to claim 9, in which the first electroluminescent element is energised for longer periods than the second electroluminescent element.

11. A light-emitting device according to claim 10, in which the first electroluminescent element is pulsed more frequently or with a greater pulse width than the second electroluminescent element.

12. A light-emitting device according to any one of claims 9 to 11, in which over a given period the ratio between energization times for the first and second electroluminescent elements is substantially equal to the ratio between the lifetimes of the second and first electroluminescent elements respectively.

13. A light-emitting device according to any one of the preceding claims, in which the second element is adapted to emit light over a larger area than the first element.

14. A light-emitting device according to claim 13, in which the ratio between the light-emitting areas of the first and second electroluminescent elements is substantially equal to the ratio between the brightness of the second electroluminescent element and the brightness of the first electroluminescent element when energised for equal periods.

15. A light-emitting device according to any one of claims 1 to 14, in which the first and second colours of light emission are selected from the group consisting of red, green and blue.

16. A light-emitting device according to any one of the preceding claims, in which the ratio between the brightness of the first electroluminescent element and the brightness of the second electroluminescent element is substantially equal to the ratio between the active lifetime of the first electroluminescent element and the active lifetime of the second electroluminescent element.

17. A light-emitting device according to any one of claims 1 to 16, further comprising a third electroluminescent element for emitting light of a third colour when energised, the third electroluminescent element having an active lifetime in between that of the first and second electroluminescent elements.

18. A light-emitting device according to claim 17, in which the third electroluminescent element is energised by the same potential as the first electroluminescent element.

19. A light-emitting device according to claim 17 or 18 when appendent to claim 13, in which the third electroluminescent element is adapted to emit light over an area which is greater than that of the first electroluminescent element but less than that of the second electroluminescent element.

20. A graphic display comprising a light emitting device according to any one of claims 1 to 19, wherein each electroluminescent element corresponds to a pixel for displaying graphic information.

21. A light-emitting device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

22. A light-emitting device, comprising:

a first electroluminescent element for emitting light of a first brightness when energised by a predetermined potential; and

a second electroluminescent element for emitting light of a second brightness when energised by the predetermined potential, the second brightness being less than the first brightness;

characterised by means for energising the first and second electroluminescent elements at the predetermined potential, and in that the second electroluminescent element has a larger light-emitting area than the first electroluminescent element.

23. A light-emitting device according to claim 22, in which the first or second electroluminescent elements comprise an organic light emissive material.

24. A light-emitting device according to claim 23, in which the organic light emissive material is polymeric.

25. A light-emitting device according to any one of claims 22 to 24, in which the energising means comprises at least one electrode common to both electroluminescent elements.

26. A light-emitting device according to claim 25, in which the energising means comprises an anode and a cathode, each common to both electroluminescent elements.

27. A light-emitting device according to any one of claims 22 to 26, in which total light emitted by the first electroluminescent element is substantially equal to total light emitted by the second electroluminescent element in any given time interval when both electroluminescent elements are energised.

28. A light-emitting device according to any one of claims 22 to 27, in which the ratio of the first brightness to the second brightness is substantially equal to the ratio of the light-emitting area of the second electroluminescent element to the light-emitting area of the first electroluminescent element.

29. A light-emitting device according to any one of claims 22 to 28, in which the first and second electroluminescent elements emit light of first and second colours respectively when energised, the first and second colours being selected from the group consisting of red, green and blue.

30. A light-emitting device according to any one of claims 22 to 29, further comprising:

a third electroluminescent element for emitting light of a third brightness when energised by the predetermined potential, the third brightness being in between that of the first and second brightnesses; and

means for energising the third electroluminescent element at the predetermined potential.

31. A light-emitting device according to claim 30, in which the third electroluminescent element has a light-emitting area greater than that of the first element and less than that of the second element.

32. A graphic display comprising a light-emitting device according to any one of claims 22 to 31, wherein each electroluminescent element corresponds to a pixel for displaying graphic information.

33. A light-emitting device comprising:

a first electroluminescent element for emitting light of a first colour when energized; and

a second electroluminescent element for emitting light of second colour when energized, the first electroluminescent element emitting light at a lower luminance than that of the second electroluminescent element when each is energized with optimal efficiency;

characterized in that the first and second electroluminescent elements are configured to operate at the same perceived brightness when both electroluminescent elements are energized with optimal efficiency.

34. A light-emitting device according to claim 33, in which the first or second electroluminescent elements comprise organic light emissive material.

35. A light-emitting device according to claim 34, in which the organic light emissive material is polymeric.

36. A life-emitting device according to any one of claims 33 to 35, in which the first and second electroluminescent elements are energized by a common potential.

37. A light-emitting device according to any one of claims 33 to 35, in which the first and second electroluminescent elements are energized by different potentials.

38. A light-emitting device according to claim 37, in which the second electroluminescent element is energized at a higher potential than the first electroluminescent element.

39. A light-emitting device according to claim 36,37 or 38, in which the potential applied to one or both of the electroluminescent elements is pulsed.

40. A light-emitting device according to claim 39, in which the first electroluminescent element is energized for longer periods than the second electroluminescent element.

41. A light-emitting device according to claim 40, in which the first electroluminescent element is pulsed more frequently or with a greater pulse width than the second electroluminescent element.

42. A light-emitting device according to any one of claims 33 to 41, in which the first electroluminescent element is configured to emit light over a larger area than the second electroluminescent element.

43. A light-emitting device according to claim 42, in which the ratio between the light-emitting areas of the first and second electroluminescent elements is substantially equal to the ratio between the luminances of the second and first electroluminescent elements respectively when energized with optimal efficiency.

44. A light-emitting device according to any one of claims 33 to 43, in which the first and second colours of light emission are selected from the group consisting of red, green and blue.

45. A light-emitting device according to any one of claims 33 to 44, further comprising a third electroluminescent element for emitting light of a third colour when energized, the third electroluminescent element emitting light at a luminance in between that of the first and second electroluminescent elements when energized with optimal efficiency.

46. A graphic display comprising a light-emitting device according to any one of claims 33 to 45, wherein each electroluminescent element corresponds to a pixel for displaying graphic information.

47. A light-emitting device comprising:

a first electroluminescent element for emitting light of a first colour when energized; and

a second electroluminescent element for emitting light of a second colour when energized, the first electroluminescent having a half-life which is greater than that of the second electroluminescent element when each is energized with. optimal efficiency;

characterized in that the second electroluminescent element is configured to operate at a lower brightness than the first electroluminescent element when both are energized with optimal efficiency.

48. A light-emitting device according to claim 47, in which the first or second electroluminescent elements comprise organic light emissive material.

49. A light-emitting device according to claim 48, in which the organic light emissive material is polymeric.

50. A life-emitting device according to any one of claims 47 to 49, in which the first and second electroluminescent elements are energized by a common potential.

51. A light-emitting device according to any one of claims 47 to 49, in which the first and second electroluminescent elements are energized by different potentials.

52. A light-emitting device according to claim 51, in which the second electroluminescent element is energized at a higher potential than the first electroluminescent element.

53. A light-emitting device according to claim 50,51 or 52, in which the potential applied to one or both of the electroluminescent elements is pulsed.

54. A light-emitting device according to claim 53, in which the first electroluminescent element is energized for longer periods than the second electroluminescent element.

55. A light-emitting device according to claim 54, in which the first electroluminescent element is pulsed more frequently or with a greater pulse width than the second electroluminescent element.

56. A light-emitting device according to any one of claims 47 to 55, in which the first electroluminescent element is configured to emit light over a larger area than the second electroluminescent element.

57. A light-emitting device according to claim 56, in which the ratio between the light-emitting areas of the first and second electroluminescent elements is substantially equal to the ratio between the brightness of the second and first electroluminescent elements respectively when energized with optimal efficiency.

58. A light-emitting device according to any one of claims 47 to 57, in which the first and second colours of light emission are selected from the group consisting of red, green and blue.

59. A light-emitting device according to any one of claims 47 to 58, further comprising a third electroluminescent element for emitting light of a third colour when energized, the third electroluminescent element emitting light at a luminance in between that of the first and second electroluminescent elements when energized with optimal efficiency.

60. A graphic display comprising a light-emitting device according to any one of claims 47 to 59, wherein each electroluminescent element corresponds to a pixel for displaying graphic information.