Phosphor based light sources having a non-planar long pass reflector and method of making

• US 7,312,560 B2
• Filed: 12/02/2003
• Issued: 12/25/2007
• Est. Priority Date: 01/27/2003
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ouderkirk, Andrew J., Weber, Michael F., Wheatley, John A.
• Primary Examiner(s): Guharay, Karabi
• Assistant Examiner(s): QUARTERMAN, KEVIN J
• Application Number:
  US10/727,026
• Publication Number:
  US 20040145895A1
• Time in Patent Office: 1,484 Days
• Field of Search: 313/502, 313/503, 313/506, 313/512, 313/113, 257 98-100, 445/23, 445/24, 445/26, 445/27
• US Class Current: 313/113
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/01025 Manganese [Mn]
• CPC Class Codes: H01L 2924/01077 Iridium [Ir]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil

Abstract

A light source including an LED that emits excitation light, a layer a phosphor material positioned to receive the excitation light, the phosphor material emitting visible light when illuminated with the excitation light, and a first non-planar flexible multilayer reflector that reflects the excitation light and transmits visible light. The non-planar flexible multilayer reflector is positioned to reflect LED light onto the phosphor material.

Claims

1. A light source, comprising:

an LED that emits excitation light;

a layer of phosphor material positioned to receive the excitation light, the phosphor material emitting visible light when illuminated with the excitation light; and

a non-planar polymeric multilayer reflector that reflects the excitation light and transmits visible light, the non-planar polymeric multilayer reflector being positioned to reflect the excitation light onto the phosphor material;

wherein the non-planar polymeric multilayer reflector has a non-uniform thickness.

2. The light source of claim 1, wherein the non-planar polymeric multilayer reflector comprises alternating layers of a first and second thermoplastic polymer and wherein at least some of the layers are birefringent.

3. The light source of claim 1, wherein the excitation light comprises UV light.

4. The light source of claim 1, wherein the non-planar polymeric multilayer reflector is concave.

5. The light source of claim 1, wherein the non-planar polymeric multilayer reflector is hemispherically concave.

6. The light source of claim 1, wherein the layer of phosphor material is disposed between the LED and the non-planar polymeric multilayer reflector.

7. The light source of claim 1, wherein the non-planar polymeric multilayer reflector has a first thickness at an inner region of the non-planar polymeric multilayer reflector and a second thickness at an outer region of the non-planar polymeric multilayer reflector and the first thickness is different than the second thickness.

8. The light source of claim 7, wherein the first thickness is greater than the second thickness.

9. The light source of claim 7, wherein the first thickness is less than the second thickness.

10. The light source of claim 1, wherein the non-planar polymeric multilayer reflector includes polymeric material that resists degradation when exposed to UV light.

11. The light source of claim 1, wherein the non-planar polymeric multilayer reflector is substantially free of inorganic materials.

12. The light source of claim 1, wherein the layer of phosphor material comprises particles of phosphor material dispersed in a binder.

13. The light source of claim 12, wherein the layer of phosphor material is discontinuous, comprising a plurality of distinct regions.

14. The light source of claim 13, wherein each region has an area of less than 10000 microns².

15. The light source of claim 13, wherein the regions comprise a first region that emits red light, a second region that emits green light, and a third region that emits blue light, when illuminated with the excitation light.

16. The light source of claim 1, further comprising:

a multilayer reflector that reflects visible light and transmits the excitation light disposed between the LED and the phosphor material.

17. The light source of claim 16, wherein the multilayer reflector comprises polymeric material.

18. The light source of claim 16, wherein the multilayer reflector comprises alternating layers of a first and second thermoplastic polymer and wherein at least some of the layers are birefringent.

19. The light source of claim 16, wherein the non-planar polymeric multilayer reflector is concave.

20. The light source of claim 16, wherein the multilayer reflector is concave and polymeric.

21. The light source of claim 16, wherein the non-planar polymeric multilayer reflector is hemispherically concave.

22. The light source of claim 16, wherein the multilayer reflector is hemispherically concave.

23. The light source of claim 16, wherein the non-planar polymeric multilayer reflector comprises a polymeric material that resists degradation when exposed to UV light and the multilayer reflector comprises a polymeric material that resists degradation when exposed to UV light.

24. The light source of claim 16, wherein the non-planar polymeric multilayer reflector is substantially free of inorganic materials and the multilayer reflector is substantially free of inorganic materials.

25. The light source of claim 16, wherein the non-planar polymeric multilayer reflector is hemispherically concave and the multilayer reflector is hemispherically concave.

26. The light source of claim 25, wherein the layer of phosphor material is disposed between the non-planar polymeric multilayer reflector and the multilayer reflector.

27. The light source of claim 16, wherein the layer of phosphor material comprises particles of phosphor material dispersed in a binder.

28. The light source of claim 27, wherein the layer of phosphor material is discontinuous, comprising a plurality of distinct regions.

29. The light source of claim 28, wherein each region has an area of less than 10000 microns².

30. The light source of claim 28, wherein the regions comprise a first region that emits red light, a second region that emits green light, and a third region that emits blue light, when illuminated with the excitation light.

31. The light source of claim 28, wherein at least a first region emits light at a first wavelength and a second region emits light at a second wavelength different than the first wavelength.

32. A method of manufacturing a light source, comprising the steps of:

providing an LED that emits excitation light;

positioning a layer of phosphor material such that the phosphor material emits visible light when illuminated with the excitation light; and

positioning a non-planar polymeric multilayer reflector to reflect the excitation light onto the phosphor material and transmit visible light, the non-planar polymeric multilayer reflector having a non-uniform thickness.

33. The method of claim 32, wherein the non-planar polymeric multilayer reflector comprises alternating layers of a first and second thermoplastic polymer and wherein at least some of the layers are birefringent.

34. The method of claim 32, further comprising the step of shaping a polymeric multilayer reflector to form the non-planar polymeric multilayer reflector.

35. The method of claim 32, further comprising the step of thermoforming a polymeric multilayer reflector to form the non-planar polymeric multilayer reflector.

36. The method of claim 32, further comprising the step of patterning the layer of phosphor material so that such layer is discontinuous.

37. A light source, comprising:

an LED that emits excitation light;

a layer of phosphor material positioned to receive the excitation light, the phosphor material emitting visible light when illuminated with the excitation light;

a non-planar polymeric multilayer reflector that reflects the excitation light and transmits visible light, the non-planar polymeric multilayer reflector being positioned to reflect the excitation light onto the phosphor material; and

a multilayer reflector that reflects visible light and transmits the excitation light disposed between the LED and the phosphor material.

38. The light source of claim 37, wherein the multilayer reflector comprises polymeric material.

39. The light source of claim 37, wherein the multilayer reflector comprises alternating layers of a first and second thermoplastic polymer and wherein at least some of the layers are birefringent.

40. The light source of claim 37, wherein the non-planar polymeric multilayer reflector is concave.

41. The light source of claim 37, wherein the multilayer reflector is concave and polymeric.

42. The light source of claim 37, wherein the non-planar polymeric multilayer reflector is hemispherically concave.

43. The light source of claim 37, wherein the multilayer reflector is hemispherically concave.

44. The light source of claim 37, wherein the non-planar polymeric multilayer reflector comprises a polymeric material that resists degradation when exposed to UV light and the multilayer reflector comprises a polymeric material that resists degradation when exposed to UV light.

45. The light source of claim 37, wherein the non-planar polymeric multilayer reflector is substantially free of inorganic materials and the multilayer reflector is substantially free of inorganic materials.

46. The light source of claim 37, wherein the non-planar polymeric multilayer reflector is hemispherically concave and the multilayer reflector is hemispherically concave.

47. The light source of claim 46, wherein the layer of phosphor material is disposed between the first and second non-planar polymeric multilayer reflector and the multilayer reflector.

48. The light source of claim 37, wherein the layer of phosphor material comprises particles of phosphor material dispersed in a binder.

49. The light source of claim 48, wherein the layer of phosphor material is discontinuous, comprising a plurality of distinct regions.

50. The light source of claim 49, wherein each region has an area of less than 10000 microns².

51. The light source of claim 49, wherein the regions comprise a first region that emits red light, a second region that emits green light, and a third region that emits blue light, when illuminated with the excitation light.

52. The light source of claim 49, wherein at least a first region emits light at a first wavelength and a second region emits light at a second wavelength different than the first wavelength.

53. A method of manufacturing a light source, comprising the steps of:

providing an LED that emits excitation light;

positioning a layer of phosphor material such that the phosphor material emits visible light when illuminated with the excitation light;

positioning a non-planar polymeric multilayer reflector to reflect the excitation light onto the phosphor material and transmit visible light; and

positioning a multilayer reflector between the LED and the phosphor material to reflect visible light and transmits the excitation light.

54. The method of claim 53, wherein the non-planar polymeric multilayer reflector comprises alternating layers of a first and second thermoplastic polymer and wherein at least some of the layers are birefringent.

55. The method of claim 53, further comprising the step of shaping a polymeric multilayer reflector to form the non-planar polymeric multilayer reflector.

56. The method of claim 53, further comprising the step of thermoforming a polymeric multilayer reflector to form the non-planar polymeric multilayer reflector.

57. The method of claim 53, further comprising the step of patterning the layer of phosphor material so that such layer is discontinuous.