Phosphor converted light emitting device

• US 7,038,370 B2
• Filed: 02/23/2004
• Issued: 05/02/2006
• Est. Priority Date: 03/17/2003
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Schmidt, Peter J., Mueller-Mach, Regina B., Mueller, Gerd O., Juestel, Thomas, Busselt, Wolfgang, Mayr, Walter
• Primary Examiner(s): Patel, Ashok
• Assistant Examiner(s): Canning, Anthony J.
• Application Number:
  US10/785,620
• Publication Number:
  US 20040256974A1
• Time in Patent Office: 799 Days
• Field of Search: 313483-487, 313/503, 313/512, 313/581, 252/301.4 R, 252/301.4 F, 252/301.4 S, 257 98-100, 315/169.3, 315/169.4, 345/36, 345/37, 345/41, 345/45, 345/47, 345/60, 345/75, 345/76
• US Class Current: 313/485
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 33/502 Wavelength conversion materials

Abstract

A system includes a radiation source capable of emitting first light and a fluorescent material capable of absorbing the first light and emitting second light having a different wavelength than the first light. The fluorescent material is a phosphor having the formula (Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂:Ce_aPr_b wherein 0<x<1, 0<y<1, 0<z≦0.1, 0<a≦0.2 and 0<b≦0.1. In some embodiments, the (Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂:Ce_aPr_b is combined with a second fluorescent material capable of emitting third light. The second fluorescent material may be a red-emitting phosphor, such that the combination of first, second, and third light emitted from the system appears white.

Claims

1. A system comprising:

a radiation source capable of emitting first light; and

a fluorescent material capable of absorbing the first light and emitting second light having a different wavelength than the first light, wherein said fluorescent material comprises a phosphor having the formula (Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂;

Ce_aPr_b wherein 0<

x<

1, 0<

y<

1, 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1.

2. The system of claim 1 wherein the first light comprises light having a peak emission wavelength in the range of 400 to 480 nm.

3. The system of claim 1 wherein the first light comprises light having a peak emission wavelength in the range of 438 to 456 nm.

4. The system of claim 1 wherein the first light comprises light having a peak emission wavelength in the range of 330 to 365 nm.

5. The system of claim 1 wherein the radiation source is a light emitting diode.

6. The system of claim 1 wherein the second light is green light.

7. The system of claim 1 wherein the fluorescent material is a first fluorescent material, the system further comprising a second fluorescent material capable of emitting third light.

8. The system of claim 7 wherein the third light comprises red light.

9. The system of claim 7 wherein the second fluorescent material comprises an Eu(II)-activated phosphor.

10. The system of claim 7 wherein the second fluorescent material comprises (Sr_1-x-yBa_xCa_y)₂Si_5-xAl_xN_8-xO_x:

Eu wherein 0≦

a<

5, 0<

x≦

1, 0≦

y≦

1, and 0<

z≦

1.

11. The system of claim 7 wherein the second fluorescent material comprises Sr₂Si₅N₈:

Eu²⁺.

12. The system of claim 7 wherein the second fluorescent material comprises (Sr_1-xCa_x)S:

Eu.

13. The system of claim 7 wherein:

the first fluorescent material and the second fluorescent material are disposed over the radiation source as discrete layers; and

the second fluorescent material is closer to the radiation source than the first fluorescent material.

14. The system of claim 13 further comprising a layer of transparent material disposed between the first fluorescent material and the second fluorescent material.

15. The system of claim 7 wherein:

the first fluorescent material is disposed over a first portion of the radiation source; and

the second fluorescent material is disposed over a second portion of the radiation source.

16. The system of claim 7 wherein:

the first fluorescent material is disposed over the radiation source in a plurality of first discrete regions; and

the second fluorescent material is disposed over the radiation source in a plurality of second discrete regions.

17. The system of claim 16 wherein the plurality of first discrete regions and the plurality of second discrete regions form a pattern.

18. The system of claim 16 further comprising a transparent material disposed over the radiation source in a plurality of third discrete regions.

19. The system of claim 7 wherein:

the second fluorescent material is disposed over the radiation source in a plurality of first discrete regions; and

the first fluorescent material is disposed over the second fluorescent material.

20. The system of claim 7 further comprising a third fluorescent material capable of emitting fourth light.

21. The system of claim 20 wherein the fourth light comprises blue light.

22. The system of claim 1 wherein particles of the first fluorescent material are coated with a layer of one or more compounds selected from the group formed by the fluorides and orthophosphates of the elements aluminum, scandium, yttrium, lanthanum gadolinium and lutetium, the oxides of aluminum, yttrium and lanthanum and the nitride of aluminum.