Pulsed LED scan-ring array for boosting display system lumens

• US 20050128441A1
• Filed: 12/10/2003
• Published: 06/16/2005
• Est. Priority Date: 12/10/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Morgan, Daniel J.
• Granted Patent: US 7,289,090 B2
• Time in Patent Office: Days
• US Class Current: 353/102
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: H04N 9/3138 using arrays of modulated light sources electroluminescent display devices G09G3/30

Abstract

A display apparatus 200 includes a substrate 219 and a number of light emitting diodes (LEDs) 202 coupled to the substrate. An optical element 207 such as a shroud or an integrator rod is located adjacent to at least one of the LEDs. In operation, the optical element and the LEDs are movable relative to one another so that the optical element is adjacent to different ones of the LEDs at different times.

Claims

1. A display apparatus comprising:

a substrate;

a plurality of light emitting diodes (LEDs) coupled to the substrate; and

an optical element located adjacent to at least one of the LEDs, wherein the optical element and the plurality of LEDs are movable relative to one another so that the optical element is adjacent to different ones of the LEDs at different times.

2. The apparatus of claim 1 wherein the plurality of LEDs comprises a plurality of red LEDs, a plurality of blue LEDs and a plurality of green LEDs.

3. The apparatus of claim 2 wherein the plurality of LEDs includes at least half green LEDs.

4. The apparatus of claim 1 and further comprising a motor coupled to the optical element so that the optical element rotates relative to the plurality of LEDs.

5. The apparatus of claim 1 wherein the LEDs comprises a plurality of LED dies mounted on the substrate.

6. The apparatus of claim 5 wherein the plurality of LEDs is mounted in a substantially circular configuration on the substrate.

7. The apparatus of claim 1 wherein the substrate comprises a printed circuit board such that the plurality of LEDs comprises a plurality of packaged LEDs mounted on the printed circuit board.

8. The apparatus of claim 1 wherein the substrate comprises a LED interconnect layer overlying a heat sink.

9. The apparatus of claim 1 wherein the substrate comprises a semiconductor substrate.

10. The apparatus of claim 1 wherein the LEDs comprise a plurality of bare LED dies, the apparatus further comprising a microlens array overlying the plurality of bare LED die.

11. The apparatus of claim 1 wherein the optical element comprises a shroud.

12. The apparatus of claim 1 wherein the optical element comprises an integrator rod.

13. The apparatus of claim 1 wherein the optical element comprises a first lens, the apparatus further comprising a first mirror, a second mirror and a second lens, wherein light from an LED adjacent the optical element is directed through the first lens toward and reflected from the first mirror and the second mirror and then through the second lens.

14. The apparatus of claim 1 wherein the plurality of LEDs are connected to a rotatable substrate that is operable to rotate relative to the optical element.

15. The apparatus of claim 14 and further comprising a motor coupled to the substrate, the motor receiving power through a plurality of brush contacts.

16. A display apparatus comprising:

a plurality of LEDs mounted along a periphery of a substrate;

a microlens array overlying the plurality of LEDs;

a motor located in substantial alignment with a center point of the substrate; and

an optical collection shroud coupled to the motor so as to rotate relative to the plurality of LEDs.

17. The apparatus of claim 16 and further comprising a heat sink attached to the substrate.

18. The apparatus of claim 16 wherein the plurality of LEDs comprises a plurality of red LEDs, a plurality of blue LEDs and a plurality of green LEDs.

19. The apparatus of claim 18 wherein the plurality of LEDs includes at least half green LEDs.

20. The apparatus of claim 16 wherein the plurality of LEDs is mounted in a substantially oval configuration on the substrate.

21. The apparatus of claim 16 wherein the plurality of LEDs is mounted in a substantially circular configuration on the substrate.

22. The apparatus of claim 16 and further comprising an integrator rod located to receive light from the optical collection shroud.

23. The apparatus of claim 16 wherein the optical collection shroud includes a body and at least one optical element affixed to the body.

24. The apparatus of claim 23 wherein the at least one optical element comprises a mirror.

25. The apparatus of claim 23 wherein the at least one optical element comprises a lens.

26. The apparatus of claim 23 wherein the at least one optical element comprises a first mirror, a second mirror and a lens.

27. A display system comprising:

a plurality of LEDs;

an optical element located to receive light from at least one of the LEDs, the optical element and the plurality of LEDs being movable relative to each other so that the optical element is adjacent to different ones of the LEDs at different times;

an integrator rod located to receive light from the optical element;

a relay lens located to receive light from the integrator rod;

a spatial light modulator located to receive light from the relay lens; and

a projection lens located to receive light from the spatial light modulator.

28. The system of claim 27 wherein the spatial light modulator comprises a digital micromirror device.

29. The system of claim 27 wherein the plurality of LEDs are mounted on a printed circuit board, the system further comprising a motor coupled to the optical element to cause the optical element to move relative to the printed circuit board.

30. The system of claim 27 and further comprising control electronics coupled to the spatial light modulator to control the state of pixel elements within the spatial light modulator.

31. The system of claim 30 and further comprising a light sensor located in a light path between the first integrator rod and the projection lens, the light sensor including an output coupled to the control electronics.

32. The system of claim 27 wherein the optical element comprises a second integrator rod.

33. The system of claim 27 wherein the optical element comprises an optical collection shroud.

34. The system of claim 33 wherein the optical collection shroud includes a body and at least one optical element affixed to the body.

35. The system of claim 34 wherein the at least one optical element comprises a mirror.

36. The system of claim 34 wherein the at least one optical element comprises a lens.

37. The system of claim 34 wherein the at least one optical element comprises a first mirror, a second mirror and a lens.

38. A method of displaying video signals using a plurality of LEDs and an optical element, the method comprising:

sequentially turning on ones of the plurality of LEDs;

directing light from turned-on LEDs to an optical element by moving at least one of the plurality of LEDs or the optical element so that the optical element is adjacent the turned on ones of the LEDs;

directing the light from the optical element toward a spatial light modulator; and

directing a modulated version of the light from the spatial light modulator.

39. The method of claim 38 wherein the ones of the plurality of LEDs are sequentially turned on in a manner such that each of the LEDs is turned on once during a cycle time and no LED is turned on for longer than about 15% of the cycle time.

40. The method of claim 39 wherein each cycle time has a duration of {fraction (1/120)} seconds.

41. The method of claim 38 wherein directing light from turned-on LEDs to an optical element includes moving the optical element without moving the plurality of LEDs.

42. The method of claim 38 wherein directing light from turned-on LEDs to an optical element includes moving the plurality of LEDs without moving the optical element.

43. The method of claim 38 wherein the plurality of LEDs comprises a plurality of red LEDs, a plurality of blue LEDs and a plurality of green LEDs.

44. The method of claim 38 wherein the optical element comprises an optical collection shroud.

45. The method of claim 38 and further comprising:

measuring an intensity of light being transmitted from the turned-on LEDs; and

controlling the spatial light modulator based on the measured intensity.

46. The method of claim 45 wherein controlling the spatial light modulator comprises adjusting a clock signal provided to the spatial light modulator.

47. The method of claim 38 and further comprising:

measuring an intensity of light being transmitted from the turned-on LEDs; and

controlling a power level provided to the plurality of LEDs based on the measured intensity.

48. The method of claim 38 and further comprising:

measuring an intensity of light being transmitted from the turned-on LEDs; and

altering a duty cycle of selected ones of the LEDs based on the measured intensity.

49. The method of claim 38 wherein the spatial light modulator comprises a digital micromirror device.

50. The method of claim 38 wherein the optical element comprises an integrator rod.

51. A display system comprising:

a first plurality of LEDs arranged in a ring;

an optical element located to receive light from at least one of the LEDs, the optical element and the first plurality of LEDs being movable relative to each other so that the optical element is adjacent to different ones of the LEDs at different times;

a second plurality of LEDs;

an optical integrator located to receive light from the optical element and the second plurality of LEDs;

a relay lens located to receive light from the optical integrator; and

a spatial light modulator located to receive light from the relay lens.

52. The system of claim 51 wherein the second plurality of LEDs are arranged in a ring, the system further comprising a second optical element located to receive light from at least one of the LEDs of the second plurality, the second optical element and the second plurality of LEDs being movable relative to each other so that the second optical element is adjacent to different ones of the LEDs at different times.

53. The system of claim 52 wherein the first plurality of LEDs includes LEDs of a first color and LEDs of a second color and the second plurality of LEDs includes LEDs of a third color.

54. The system of claim 52 and further comprising:

a third plurality of LEDs are arranged in a ring; and

a third optical element located to receive light from at least one of the LEDs of the third plurality, the third optical element and the third plurality of LEDs are movable relative to each other so that the third optical element is adjacent to different ones of the LEDs at different times, wherein the optical integrator is located to receive light from the third optical element.

55. The system of claim 53 wherein the first plurality of LEDs includes LEDs of a first color, the second plurality of LEDs includes LEDs of a second color, and the third plurality of LEDs includes LEDs of a third color.

56. The system of claim 51 wherein the second plurality of LEDs are arranged in a fixed array.

57. The system of claim 56 wherein the first plurality of LEDs includes LEDs of a first color and LEDs of a second color and the second plurality of LEDs includes LEDs of a third color.

58. The system of claim 56 and further comprising a third plurality of LEDs, the optical integrator located to receive light from the third plurality of LEDs.

59. The system of claim 58 wherein the third plurality of LEDs are arranged in a ring array.

60. The system of claim 51 and further comprising a projection lens located to receive light from the spatial light modulator.

61. The system of claim 51 wherein the spatial light modulator comprises a digital micromirror device.

62. The system of claim 51 wherein the first plurality of LEDs are mounted on a substrate, the system further comprising a motor coupled to the optical element to cause the optical element to move relative to the substrate.

63. The system of claim 51 and further comprising control electronics coupled to the spatial light modulator to control the state of pixel elements within the spatial light modulator.

64. The system of claim 63 and further comprising a light sensor located in a light path between the optical integrator and the projection lens, the light sensor including an output coupled to the control electronics.

65. The system of claim 51 wherein the optical element comprises a shroud.

66. The system of claim 65 wherein the shroud includes a body and at least one optical element affixed to the body.

67. The system of claim 66 wherein the at least one optical element comprises a mirror.

68. The system of claim 66 wherein the at least one optical element comprises a lens.

69. The system of claim 66 wherein the at least one optical element comprises a first mirror, a second mirror and a lens.