Enhanced color rendering index emitter through phosphor separation

Patent metadata

Field	Value
Publication number	US-9275979-B2
Application number	US-201113028863-A
Country	US
Kind code	B2
Filing date	Feb 16, 2011
Priority date	Mar 3, 2010
Publication date	Mar 1, 2016
Grant date	Mar 1, 2016

Abstract

LED packages, and LED lamps and bulbs, are disclosed that are arranged to minimize the CRI and efficiency losses resulting from the overlap of conversion material emission and excitation spectrum. In different devices having conversion materials with this overlap, the present invention arranges the conversion materials to reduce the likelihood that re-emitted light from a first conversion materials will encounter the second conversion material to minimize the risk of re-absorption. In some embodiments this risk is minimized by different arrangements where there is separation between the two phosphors. In some embodiments this separation results less than 50% of re-emitted light from the one phosphor passing into the phosphor where it risks re-absorption.

First claim

We claim:

1. A solid state lamp, comprising:
a light emitting diode (LED) on a surface;
a first conversion material with light from said LED passing through said first conversion material, wherein said first conversion material converts and re-emits at least some of said LED light;
a second conversion material on said surface and spaced from said first conversion material by an optical cavity, with light from said LED passing through said second conversion material, wherein said second conversion material converts and re-emits at least some of said LED light;
wherein said first conversion material comprises an excitation spectrum that overlaps with the emission spectrum of said second conversion material.

2. The lamp of claim 1 , wherein said first conversion material comprises an emission spectrum that does not overlap with the excitation spectrum of said second conversion material.

3. The lamp of claim 1 , wherein said second conversion material is over said first conversion material.

4. The lamp of claim 1 , wherein said second conversion material comprises a dome over said first conversion material.

5. The lamp of claim 1 , wherein said first conversion material absorbs light from said LED and re-emits red light.

6. The lamp of claim 1 , wherein said second conversion material absorbs light from said LED and re-emits yellow or green light.

7. The lamp of claim 1 , wherein less than 25% of the light re-emitted from said second conversion material passes into said first conversion material.

8. The lamp of claim 1 , emitting a white light combination or light from at least two of the sources comprising said LED, said first conversion material and said second conversion material.

9. The lamp of claim 1 , wherein said second conversion material is in a globe over said light emitting diode.

10. The lamp of claim 9 , further comprising a diffuser over said globe.

11. The lamp of claim 1 , wherein said lamp emits light comprising an emission pattern that is compliant with Energy Star standards.

12. The lamp of claim 1 , sized to fit an A19 size profile.

13. The lamp of claim 1 , wherein said second conversion material is planar.

14. The lamp of claim 1 , further comprising a planar diffuser.

15. A solid state lamp, comprising:
a plurality of light emitting diodes (LEDs);
a first red phosphor and a second red phosphor different than said first red phosphor, at least one of said first and second red phosphors on a first of said LEDs, with light from said first LED passing through said at least one red phosphor; and
a yellow or green phosphor separated from and over said LEDs, light from said LEDs passing through said yellow or green phosphor, wherein said first and second red phosphors comprise excitation spectrums that overlap with the emission spectrum of said yellow or green phosphor.

16. The lamp of claim 15 , wherein said at least one of said plurality of LEDs emits blue light.

17. The lamp of claim 15 , wherein at least one of said plurality of LEDs is uncoated by red phosphor.

18. The lamp of claim 17 , wherein said at least one uncoated LED emits blue light.

19. The lamp of claim 15 , wherein said first and second red phosphors comprise conformal coats over said first and second LEDs, respectively.

20. The lamp of claim 15 , wherein said yellow or green phosphor is over said first and second red phosphors.

21. The lamp of claim 15 , wherein less than 10% of the light re-emitted from said yellow or green phosphor passes into said first and second red phosphors.

22. A solid state lamp, comprising:
a light emitting diode (LED) emitting a first wavelength of light;
a conformal coating comprising a first phosphor on said LED, said coating absorbing some of the light emitted from said LED and re-emitting a second wavelength of light; and
a second phosphor spaced from said first phosphor by an optical cavity, with light from said LED passing through said second phosphor, said second phosphor absorbing at least some of said first wavelength of light and re-emitting a third wavelength of light, wherein the emission spectrum of said second phosphor overlaps the excitation spectrum of said first phosphor, and wherein the majority of light from said second phosphor does not encounter said first phosphor.

23. The lamp of claim 22 , wherein said second phosphor is over said first phosphor.

24. The lamp of claim 22 , wherein said second phosphor comprises a dome over said first phosphor.

25. The lamp of claim 22 , wherein the emission spectrum of said first phosphor does not overlap the excitation spectrum of said second phosphor.

26. The lamp of claim 22 , wherein the LED emits blue light.

27. The lamp of claim 22 , wherein said first phosphor absorbs light from said LED and re-emits red light.

28. The lamp of claim 22 , wherein said second phosphor absorbs light from said LED and re-emits yellow or green light.

29. The lamp of claim 22 , wherein said first phosphor comprises a red phosphor and said second phosphor comprise a yellow or green phosphor, said red phosphor comprising an excitation spectrum that at least partially overlaps with the emission spectrum of said yellow or green phosphor.

30. The lamp of claim 22 , wherein less than 10% of the light re-emitted from said second phosphor passes into said first phosphor.

31. The lamp of claim 1 , wherein said first and second conversion materials are configured to minimize absorption of light passing through said first conversion material that has been re-emitted by said second conversion material.

32. The lamp of claim 1 , wherein said surface is a substantially flat surface.

33. The lamp of claim 32 , wherein said second conversion material is dome-shaped.

34. The lamp of claim 33 , wherein the bottom of said dome-shaped second conversion material is substantially coplanar with said LED.

35. The lamp of claim 1 , wherein said second conversion material is globe-shaped; and
wherein the bottom of said globe-shaped conversion material is substantially coplanar with or below said surface.

36. The lamp of claim 35 , wherein the bottom of said globe-shaped conversion material is below said substantially flat surface.

37. The lamp of claim 1 , wherein said first conversion material is conformally coated on said LED.

38. The lamp of claim 15 , wherein said first and second red phosphors and said yellow or green phosphor are configured to minimize absorption of light passing through said first and second red phosphors that has been re-emitted by said yellow or green phosphor and to minimize absorption of light passing through said yellow or green phosphor that has been re-emitted by said first and second red phosphors.

39. The lamp of claim 15 , wherein said first and second red phosphors are on different ones of said plurality of LEDs.

40. The lamp of claim 39 , wherein said different ones of said plurality of LEDs emit the same wavelength of light.

41. The lamp of claim 40 , wherein said first and second red phosphors re-emit different wavelengths of light.

42. The lamp of claim 15 , wherein said first and second red phosphors re

Assignees

• Tong Tao
• Letoquin Ronan
• Keller Bernd
• Ibbetson James
• Negley Gerald
• Cree Inc

Inventors

• Tong Tao
• Letoquin Ronan
• Keller Bernd
• Ibbetson James
• Negley Gerald

Classifications

• H10W90/736

  between a chip and a stacked lead frame, conducting package substrate or heat sink · CPC title

• H10W74/00

  Encapsulations, e.g. protective coatings · CPC title

• H10W72/884

  Die-attach connectors and bond wires · CPC title

• H10W90/00 Primary

  Package configurations · CPC title

• H10H20/8515

  not being in contact with the bodies · CPC title