Multiple conversion material light emitting diode package and method of fabricating same

• US 9,012,937 B2
• Filed: 10/10/2007
• Issued: 04/21/2015
• Est. Priority Date: 10/10/2007
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd, Ibbetson, James
• Primary Examiner(s): Page, Dale E
• Application Number:
  US11/974,431
• Publication Number:
  US 20090095966A1
• Time in Patent Office: 2,750 Days
• Field of Search: 313/487, 313/504, 362/231, 257/99, 257/98, 257/89, 257/100, 257/E25.02
• US Class Current: 257/98
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: C09K 11/77347 Silicon Nitrides or Silicon Oxynitrides
• 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

An emitter package comprising a light emitting diode (LED) emitting light at a wavelength within a wavelength range and a plurality of phosphors. Each of the phosphors absorbs at least some light from the LED and re-emits a different wavelength of light. The package emits a combination of light from the LED and the plurality of phosphors, with the phosphors having excitation characteristics such that the emitter package emits light within a standard deviation of a target color for LEDs emitting at the wavelengths with the wavelength range. A method for fabricating emitter packages comprising fabricating a plurality of LEDs, each of which emits at a wavelength within a range of wavelengths. Each of the LEDs are arranged in a respective package with a plurality of conversion materials so that at least some light from each of the LEDs is absorbed and re-emitted by its corresponding conversion materials. The plurality of conversion materials have excitation characteristics that compensate for different LED emission wavelengths within the LED range of wavelengths such that each of the LED packages emits light within a standard deviation from a target color.

Claims

1. An emitter package, comprising:

a plurality of light emitting diodes (LED) emitting light within a wavelength range, wherein said wavelength range width is at least 10 nm and up to 50 nm;

a plurality of phosphors, said plurality of phosphors comprising at least two different phosphors, said at least two different phosphors having emission wavelengths and excitation characteristics such that a first of said phosphors has an increased excitation efficiency at longer wavelengths, within said wavelength range, compared to a second of said phosphors having a decreased excitation efficiency at the same longer wavelengths, each of which absorbs at least some light from said LED and re-emits a different wavelength of light, wherein the same plurality of phosphors is over at least two of said LEDs; and

wherein said emitter package emits a combination of light from said LED and said plurality of phosphors, in which said package emission is within a 4-step MacAdam ellipse around a target color, regardless of variations in the wavelength emitted, within said wavelength range, from said LED.

2. The emitter package of claim 1, wherein said emitter package emitting a white light combination of light from said LED and said phosphors.

3. The emitter package of claim 1, wherein said plurality of phosphors comprises two phosphors.

4. The emitter package of claim 1, wherein said range of emission wavelengths is approximately 430 to 480 nm and said plurality of phosphors comprises first and second phosphors having peak emissions at approximately 560 and approximately 570 nm, respectively.

5. The emitter package of claim 4, having a white color target approximately on the black body locus (BBL) of a CIE color coordinate system.

6. The emitter package of claim 1, wherein said wavelength range is 430 to 480 nm and said plurality of phosphors comprises first and second phosphors having peak emissions at 500 to 560 nm and 570 to 630 nm, respectively.

7. The emitter package of claim 6, wherein said target color temperature falls within the white range on the black body locus (BBL) of a CIE color coordinate system.

8. The emitter package of claim 1, wherein said range of emission wavelengths is approximately 430 to 480 nm and said first and second phosphors having peak emission at approximately 500 to 560 nm and 570 to 630 nm, respectively.

9. The emitter package of claim 8, having a white color target approximately on the black body locus (BBL) of a CIE color coordinate system.

10. The emitter package of claim 8, having a cool white color target with a correlated color temperature (CCT) between about 5,000K and about 10,000K approximately on the black body locus (BBL) of a CIE color coordinate system.

11. The emitter package of claim 8, having a warm white color target with a correlated color temperature (CCT) between about 2,000K and about 5,000K approximately on the black body locus (BBL) of a CIE color coordinate system.

12. The emitter package of claim 1, wherein said plurality of phosphors comprise two phosphors of the general composition (Ba_1-x-ySr_xCa_y)SiO₄:

Eu with emission wavelengths at approximately 520 nm and 585 nm, respectively.

13. The emitter package of claim 1, wherein said emitter package emits light within a 2-step MacAdam ellipse of said target color.

14. The emitter package of claim 1, wherein said emitter package emits light within a 3-step MacAdam ellipse of said target color.

15. The emitter package of claim 1, wherein said plurality of phosphors comprises first and second phosphors, said first phosphor re-emitting light with greater intensity when said LED emits at lower wavelengths, and said second phosphor re-emitting light with greater intensity when said LED emits at higher wavelengths.

16. The emitter package of claim 1, comprising first and second LEDs emitting light within said wavelength range.

17. The emitter package of claim 16, wherein said first and second LEDs emit different wavelengths of light.

18. The emitter package of claim 16, wherein said emitter package is configured to emit light with a color temperature substantially similar to said nominal color temperature when each of said first and second LEDs emits at any wavelength within said wavelength range.

19. An emitter package, comprising:

at least three light emitting diodes (LED) emitting light within a wavelength range, wherein said wavelength range width is at least 10 nm and up to 50 nm;

a plurality of phosphors, said plurality of phosphors comprising at least two different phosphors, said at least two different phosphors having emission wavelengths and excitation characteristics such that a first of said phosphors has an increased excitation efficiency at longer wavelengths, within said wavelength range, compared to a second of said phosphors having a decreased excitation efficiency at the same longer wavelengths, each of which absorbs at least some light from said LED and re-emits a different wavelength of light, wherein the same plurality of phosphors is over at least three of said LEDs; and

wherein said emitter package emits a combination of light from said LED and said plurality of phosphors, in which said package emission is within a 4-step MacAdam ellipse around a target color, regardless of variations in the wavelength emitted, within said wavelength range, from said LED.

20. The emitter package of claim 19, wherein said plurality of phosphors is disposed contiguously over said at least three LEDs.