High color rendering index white LED light system using multi-wavelength pump sources and mixed phosphors

• US 8,192,047 B2
• Filed: 02/15/2008
• Issued: 06/05/2012
• Est. Priority Date: 02/15/2007
• Status: Active Grant

• Current Assignee: Lighting Science Group Corporation (Pegasus Capital Advisors, L.P.)
• Original Assignee: Lighting Science Group Corporation (Pegasus Capital Advisors, L.P.)
• Inventors: Bailey, Edward, Tormey, Ellen S.
• Primary Examiner(s): MAY, ROBERT J
• Application Number:
  US12/527,087
• Publication Number:
  US 20100118510A1
• Time in Patent Office: 1,572 Days
• Field of Search: 362/231, 362/84, 257/98
• US Class Current: 362/231
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials

Abstract

The present invention relates to an LED lighting system producing light having improved Color Rendering Index (CRI). The system includes a plurality of LEDs wherein the LEDs have at least a first and second characteristic wavelength, and a mixed phosphor layer overlying at least one of a portion of the plurality of LEDs, the phosphor layer absorbing at least a portion of the LED-emitted light and producing phosphor-emitted light, wherein the phosphors includes a third characteristic wavelength and a fourth characteristic wavelength, wherein the third characteristic wavelength and fourth characteristic wavelength are not the same.

Claims

1. An LED lighting system for producing light having improved CRI, comprising:

a plurality of LEDs, each LED disposed and configured to produce respective LED-emitted light, wherein the plurality of LEDs include three blue LEDs having a first characteristic wavelength and a cyan LED having a second characteristic wavelength, wherein the first characteristic wavelength is different from the second characteristic wavelength; and

a mixed phosphor layer overlying at least a portion of one of the plurality of LEDs, the mixed phosphor layer having a first phosphor and a second phosphor disposed and configured to absorb at least a portion of the respective LED-emitted light and produce phosphor-emitted light˜

the first phosphor forming 85%-95% of the mixed phosphor layer and producing, a phosphor-emitted light of a third characteristic wavelength, the second phosphor forming 5%-15% of the mixed phosphor layer and producing a phosphor emitted light of a fourth characteristic wavelength, wherein the third characteristic wavelength is different than the fourth characteristic wavelength.

2. The LED lighting system of claim 1, wherein the phosphor-emitted light and unabsorbed LED-emitted light are combinable to produce a light having a CRI in the range of 77 to 100.

3. The LED lighting system of claim 1, wherein the mixed phosphor layer overlies all of the LEDs.

4. The LED lighting system of claim 1, wherein the mixed phosphor layer overlies a part of all of the LEDs.

5. The LED lighting system of claim 1, wherein the mixed phosphor layer overlies all of at least one LED.

6. The LED lighting system of claim 1, wherein the mixed phosphor layer is deposited directly on a surface of an LED die of each LED.

7. The LED lighting system of claim 1, wherein the mixed phosphor layer is a separate structure above the plurality of LEDs.

8. The LED lighting system of claim 1, wherein:

the first phosphor comprises a 600 nm phosphor having a characteristic wavelength of 600 nm; and

the second phosphor comprises a 573 nm phosphor having a characteristic wavelength of 573 nm, wherein the 600 nm phosphor forms 85%-95% of the mixed phosphor layer, and the 573 nm phosphor forms 5%-15% of the mixed phosphor layer.

9. The LED lighting system of claim 1, wherein:

the first phosphor comprises a 600 nm phosphor having a characteristic wavelength of 600 nm; and

the second phosphor comprises a 524 nm phosphor having a characteristic wavelength of 524 nm, wherein the 600 nm phosphor forms 85%-95% of the mixed phosphor layer, and the 524 nm phosphor forms 5%-15% of the mixed phosphor layer.

10. An LED lighting system for producing light having improved CRI, comprising:

a plurality of LEDs, each LED disposed and configured to produce respective LED-emitted light, wherein the plurality of LEDs include at least one LED having a first characteristic wavelength;

a mixed phosphor layer overlying at least a portion of one of the plurality of LEDs, the mixed phosphor layer having a first phosphor, a second phosphor, and a third phosphor disposed and configured to absorb at least a portion of the respective LED-emitted light and to produce phosphor-emitted light, the first phosphor producing at least a phosphor-emitted light of a second characteristic wavelength, the second phosphor producing a phosphor-emitted light of a third characteristic wavelength and the third phosphor producing a phosphor emitted light of a fourth characteristic wavelength, wherein the second characteristic wavelength is different than the third characteristic wavelength, the third characteristic wavelength is different than the fourth characteristic wavelength, and the fourth characteristic wavelength is different than the second characteristic wavelength;

wherein the plurality of LEDs further comprises;

one red LED;

one blue LED configured to emit 452 nm light;

one blue LED configured to emit 458 nm light; and

one cyan LED; and

the first phosphor comprises a 600 nm phosphor configured to emit 600 nm light;

the second phosphor comprises a 573 nm phosphor configured to emit 573 nm light; and

the third phosphor comprises a 524 nm phosphor configured to emit 524 nm light.

11. The LED lighting system of claim 10, wherein the phosphor-emitted light and unabsorbed LED-emitted light are combinable to produce a light having a CRI in the range of 77 to 100.

12. The LED lighting system of claim 10, wherein the mixed phosphor layer overlies all of the LEDs.

13. The LED lighting system of claim 10, wherein the mixed phosphor layer overlies a part of all of the LEDs.

14. The LED lighting system of claim 10, wherein the mixed phosphor layer overlies all of at least one LED.

15. The LED lighting system of claim 10, wherein the mixed phosphor layer is deposited directly on a surface of an LED die of each LED.

16. The LED lighting system of claim 10, wherein the mixed phosphor layer is a separate structure above the plurality of LEDs.

17. The LED lighting system of claim 10, wherein the phosphor-emitted light comprises:

16%-20% of 524 nm light;

43%-47% of 573 nm light; and

35%-39% of 600 nm light.

18. The LED lighting system of claim 10, wherein the phosphor-emitted light comprises:

17%-21% of 524 nm light;

46%-50% of 573 nm light; and

31%-35% of 600 nm light.

19. The LED lighting system of claim 10, wherein the phosphor-emitted light comprises:

39%-43% of 524 nm light;

24%-28% of 573 nm light; and

31%-35% of 600 nm light.

20. The LED lighting system of claim 10, wherein the phosphor-emitted light comprises:

44%-48% of 524 nm light;

24%-28% of 573 nm light; and

26%-30% of 600 nm light.

21. The LED lighting system of claim 10, wherein the phosphor-emitted light comprises:

41%-45% of 524 nm light;

29%-33% of 573 nm light; and

24%-28% of 600 nm light.

22. A method of producing light having improved CRI, comprising the steps:

providing a plurality of LEDs, each LED producing respective LED-emitted light, wherein the plurality of LEDs include three blue LEDs having a first characteristic wavelength and a cyan LED having a second characteristic wavelength, wherein the first characteristic wavelength is different from the second characteristic wavelength;

absorbing at least a portion of the respective LED-emitted light using a mixed phosphor layer having a first phosphor and a second phosphor, the first phosphor forming 85%-95% of the mixed phosphor layer, the second phosphor forming 5%-15% of the mixed phosphor layer, wherein the mixed phosphor layer overlies at least a portion of one of the plurality of LEDs, the mixed phosphor layer absorbing at least a portion of the respective LED-emitted light; and

emitting a phosphor-emitted light, including at least a phosphor-emitted light of a third characteristic wavelength from the first phosphor, and a phosphor emitted light of a fourth characteristic wavelength from the second phosphor;

wherein a combination of phosphor-emitted light and LED-emitted light not absorbed by the mixed phosphor layer is light having improved CRI as compared with the LED-emitted light not absorbed by the mixed phosphor layer.

23. The method of claim 22, wherein the phosphor-emitted light and the unabsorbed LED-emitted light combine to produce a light having a CRI in the range of 77 to 100.

24. The method of claim 22, wherein the mixed phosphor layer overlies all of the LEDs.

25. The method of claim 22, wherein the mixed phosphor layer overlies a part of all of the LEDs.

26. The method of claim 22, wherein the mixed phosphor layer overlies all of at least one LED.

27. The method of claim 22, wherein the mixed phosphor layer is deposited directly on a surface of an LED die of each LED.

28. The method of claim 22, wherein the mixed phosphor layer is a separate structure above the plurality of LEDs.