Solid state white light emitter and display using same

• US 9,698,313 B2
• Filed: 06/01/2008
• Issued: 07/04/2017
• Est. Priority Date: 03/26/1996
• Status: Expired due to Fees

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Baretz, Bruce, Tischler, Michael A.
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): HORIKOSHI, STEVEN Y
• Application Number:
  US12/131,119
• Publication Number:
  US 20080224598A1
• Time in Patent Office: 3,320 Days
• CPC Class Codes: G09F 13/04 Signs, boards or panels, illuminated from behind the insignia
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48139 with an intermediate bond, e.g. continuous wire daisy chain
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

A light emitting assembly comprising a solid state device coupleable with a power supply constructed and arranged to power the solid state device to emit from the solid state device a first, relatively shorter wavelength radiation, and a down-converting luminophoric medium arranged in receiving relationship to said first, relatively shorter wavelength radiation, and which in exposure to said first, relatively shorter wavelength radiation, is excited to responsively emit second, relatively longer wavelength radiation. In a specific embodiment, monochromatic blue or UV light output from a light-emitting diode is down-converted to white light by packaging the diode with fluorescent organic and/or inorganic fluorescers and phosphors in a polymeric matrix.

Claims

1. A method of obtaining a white light output of a determined chromatic character, said method comprising:

providing at least one GaN-based LED die configured to emit blue light; and

providing a luminophoric medium comprising a multiplicity of luminophoric materials in which the multiple luminophoric materials are provided in relative amounts with respect to one other so that white light of the determined chromatic character is produced as said white light output when the luminophoric medium interacts with emitted light from the at least one GaN-based LED die.

2. The method of claim 1, wherein the luminophoric materials comprise phosphor materials.

3. The method of claim 1, wherein the luminophoric materials comprise a material responsively emitting radiation in at least one of the green spectrum and the yellow spectrum.

4. The method of claim 1, wherein the luminophoric medium comprises a material emitting radiation in at least red, yellow and green spectral regions, in interaction with emitted light from the at least one GaN-based LED die.

5. The method of claim 1, wherein the luminophoric medium includes red emissive and yellow emissive species.

6. The method of claim 1, wherein the luminophoric medium includes at least one phosphor doped with cerium or europium.

7. The method of claim 1, wherein the luminophoric medium includes red, green and blue emissive centers.

8. The method of claim 1, wherein the luminophoric medium includes a red emissive center.

9. The method of claim 1, wherein multiple GaN-based LED dies are provided.

10. A method according to claim 1, further comprising packaging said luminophoric medium and said at least one GaN-based LED die.

11. The method of claim 1, comprising fabricating a light emitting display including said luminophoric medium and said at least one GaN-based LED die.

12. The method of claim 11, comprising energizing said at least one GaN-based LED die to generate said white light output of determined chromatic character for said display.

13. The method of claim 1, wherein the luminophoric medium includes red and green emissive centers.

14. The method of claim 1, wherein the at least one GaN-based LED die comprises at least one material selected from the group consisting of gallium nitride and its alloys.

15. The method of claim 14, wherein said alloys comprise aluminum gallium indium nitride, aluminum gallium nitride, and indium gallium nitride.

16. The method of claim 1, wherein the luminophoric medium comprises an inorganic luminophoric medium.

17. The method of claim 1, wherein the luminophoric medium comprises multiple inorganic phosphors.

18. The method of claim 1, wherein the luminophoric medium and said at least one GaN-based LED die are structurally associated in a light-emitting article.

19. The method of claim 18, wherein said at least one GaN-based LED die comprises a multiplicity of GaN-based LED dies.

20. The method of claim 19, wherein said multiplicity of GaN-based LED dies are arranged for simultaneous emission of light from all GaN-based LED dies in said multiplicity of GaN-based LED dies.

21. The method of claim 20, wherein said multiplicity of GaN-based LED dies and luminophoric medium provide backlighting to a display.

22. The method of claim 21, wherein said display comprises a liquid crystal display.

23. The method of claim 19, wherein said multiplicity of GaN-based LED dies are electrically coupled together.

24. The method of claim 19, in which the multiplicity of GaN-based LED dies and the luminophoric medium are structurally associated with a light-transmissive material adapted to transmit said white light output of said determined chromatic character.

25. The method of claim 1, wherein said at least one GaN-based LED die and the luminophoric medium are structurally associated with one another.

26. The method of claim 25, wherein the structural association comprises a contiguous relationship in a light emitting device.

27. The method of claim 25, wherein the structural association comprises a spaced relationship in a light emitting device.

28. The method of claim 25, wherein said at least one GaN-based LED die and the luminophoric medium are structurally associated with a light-transmissive material adapted to transmit said white light output of said determined chromatic character.

29. The method of claim 28, wherein the light-transmissive material comprises a polymeric material.

30. The method of claim 1, wherein a light-transmissive domed member encloses said at least one GAN-based LED die and the luminophoric medium.

31. The method of claim 30, wherein the light-transmissive domed member comprises a cylindrical side portion and a hemispherical top portion.

32. The method of claim 1, further comprising using the white light output of the determined chromatic character to backlight a display.

33. The method of claim 32, wherein the display comprises a liquid crystal display.

34. The method of claim 1, wherein the luminophoric medium comprises yellow fluorescer.

35. A method for obtaining white light output of a specified chromatic character, comprising:

providing at least one GaN-based LED die configured to emit blue light;

providing a luminophoric medium comprising a multiplicity of luminophoric materials in which the multiplicity of luminophoric materials are provided in relative amounts with respect one another so that a white light emission of the specified chromatic character for said white light output is produced when the luminophoric medium interacts with emitted light from the at least one GaN-based LED die; and

assembling the at least one GaN-based LED die and the luminophoric medium to form a light-emitting assembly in which the at least one GaN-based LED die is arranged to emit light for interaction with the luminophoric medium so that said white light output of said specified chromatic character is produced.

36. The method of claim 35, wherein the chromatic character of the white light emission required for said white light output is specified by a tint of said white light emission.

37. The method of claim 35, wherein the chromatic character of the white light emission required for said white light output is specified by a hue of said white light emission.

38. The method of claim 35, wherein the specified chromatic character of the white light emission required for said white light output comprises chromaticity coordinates that are specified by luminescence quantum yields of the luminophoric materials in the luminophoric medium.

39. The method of claim 38, wherein concentrations of the luminophoric materials in the luminophoric medium correlate to luminescence quantum yields of said luminophoric materials that specify said chromaticity coordinates.

40. The method of claim 39, wherein said concentrations of said luminophoric materials are between 10⁻

3 and 10 mole percent for each said luminophoric material.

41. A method of fabricating a light-emitting assembly, comprising:

providing at least one gallium nitride alloy LED configured to emit blue light;

formulating a luminophoric medium from multiple phosphor components, so that the luminophoric medium is configured to interact with light emitted from the at least one gallium nitride alloy LED to produce down-converted light, wherein the light emitted from the at least one gallium nitride alloy LED and the down-converted light produce a white light output from the light-emitting assembly;

said formulating comprising combining predetermined amounts of each of said multiple phosphor components to provide specific white light output chromaticity from among a series of white light output chromaticities; and

structurally associating the at least one gallium nitride alloy LED with the formulated luminophoric medium providing said specific white light output chromaticity, in the light-emitting assembly.

42. The method of claim 41, wherein the gallium nitride alloy of said at least one gallium nitride alloy LED is selected from the group consisting of gallium nitride, and indium gallium nitride, aluminum gallium nitride, and aluminum gallium indium nitride.

43. The method of claim 41, wherein the gallium nitride alloy of said at least one gallium nitride alloy LED comprises gallium nitride.

44. The method of claim 41, wherein the multiple phosphor components comprise inorganic phosphors.

45. The method of claim 41, wherein said amounts of each of said multiple phosphor components are predetermined based on their luminescence quantum yields.

46. The method of claim 41, wherein said amounts of each of said multiple phosphor components are predetermined based on their spectral distribution characteristics.

47. The method of claim 41, wherein the formulated luminophoric medium is structurally associated in the light-emitting assembly in spaced relationship to the at least one gallium nitride alloy LED.

48. The method of claim 47, wherein the at least one gallium nitride alloy LED comprises a multiplicity of gallium nitride alloy LEDs.

49. The method of claim 48, wherein said multiplicity of gallium nitride alloy LEDs is in a regular pattern.

50. The method of claim 41, wherein the formulated luminophoric medium is structurally associated in the light-emitting assembly in contiguous relationship to the at least one gallium nitride alloy LED.

51. The method of claim 50, wherein the at least one gallium nitride alloy LED comprises a multiplicity of gallium nitride alloy LEDs.

52. The method of claim 51, wherein said multiplicity of gallium nitride alloy LEDs is in a regular pattern.

53. The method of claim 41, wherein the light-emitting assembly comprises a wall member.

54. The method of claim 53, wherein said wall member is formed of a light-transmissive material of construction.

55. The method of claim 54, wherein said wall member is in an enclosure defining an interior volume.

56. The method of claim 55, wherein said interior volume contains the at least one gallium nitride alloy LED.

57. The method of claim 56, wherein said interior volume contains a multiplicity of gallium nitride alloy LEDs.

58. The method of claim 57, wherein said interior volume further contains at least a portion of said luminophoric medium.

59. The method of claim 54, wherein said luminophoric medium is in said wall member.

60. The method of claim 59, wherein said wall member comprises a polymeric material.

61. The method of claim 59, wherein said wall member comprises a glass material.

62. The method of claim 54, wherein said luminophoric medium is on a surface of said wall member.

63. The method of claim 62, wherein said wall member comprises a polymeric material.

64. The method of claim 62, wherein said wall member comprises a glass material.

65. The method of claim 41, wherein the light-emitting assembly is fabricated as a component of a display.

66. The method of claim 41, wherein the light-emitting assembly comprises a back light illumination assembly.

67. The method of claim 41, wherein the light-emitting assembly comprises an incandescent bulb replacement lamp.