LIGHT-EMITTING DEVICE WITH A TUNABLE LIGHT EMISSION SPECTRUM

• US 20130292717A1
• Filed: 05/04/2012
• Published: 11/07/2013
• Est. Priority Date: 05/04/2012
• Status: Abandoned Application

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Seibel, Harry A. II
• Application Number:
  US13/464,332
• Publication Number:
  US 20130292717A1
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: A01G 7/045 with electric lighting
• CPC Class Codes: F21K 9/60 Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
• 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 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: Y02P 60/14 Measures for saving energy, e.g. in green houses

Abstract

A light emitting device with a tunable light emission spectrum includes one or more blue LEDs in optical communication with n different red phosphor compositions. Each of the n different red phosphor compositions includes a different amount of strontium (Sr) and comprises light emission in a wavelength range from about 600 nm to about 675 nm. Each of the blue LEDs comprises light emission in a wavelength range from about 400 nm to about 475 nm. An m^th different red phosphor composition has a formula Ca_1-x-ySr_xEu_yAlSiN₃, with 0<x<1 and 0<y<1, and x=x_m and 1≦m≦n. A light emission spectrum of the light emitting device comprises a blue spectral component from the one or more blue LEDs and a red spectral component from the n different red phosphor compositions, where the red spectral component comprises n overlapping light emission profiles each having a different peak emission wavelength λ_m.

Claims

1. A light emitting device with a tunable light emission spectrum, the light emitting device comprising:

one or more blue light emitting diodes (LED) in optical communication with n different red phosphor compositions, each of the n different red phosphor compositions including a different amount of strontium (Sr) and comprising light emission in a wavelength range from about 600 nm to about 675 nm, the one or more blue LEDs comprising light emission in a wavelength range from about 400 nm to about 475 nm,

wherein an m^th different red phosphor composition has a formula Ca_1-x-ySr_xEu_yAlSiN₃, with 0<

x<

1 and 0<

y<

1, and x=x_m and 1≦

m≦

n, and

wherein a light emission spectrum of the light emitting device comprises a blue spectral component from the one or more blue LEDs and a red spectral component from the n different red phosphor compositions, the red spectral component comprising n overlapping light emission profiles each having a different peak emission wavelength λ

_m.

2. The light emitting device of claim 1 further comprising a plurality of the blue LEDs.

3. The light emitting device of claim 2 wherein each of the blue LEDs is in optical communication with only one of the n different red phosphor compositions.

4. The light emitting device of claim 2 wherein each of the blue LEDs is in optical communication with at least one of the n different red phosphor compositions.

5. The light emitting device of claim 2 wherein each of the blue LEDs is in optical communication with all of the n different red phosphor compositions.

6. The light emitting device of claim 2 further comprising a monolithic submount supporting the blue LEDs.

7. The light emitting device of claim 2 further comprising a plurality of LED packages, each of the blue LEDs being contained within one of the LED packages.

8. The light emitting device of claim 1 wherein at least a portion of the n different red phosphor compositions are mixed together.

9. The light emitting device of claim 1 wherein an entirety of the n different red phosphor compositions are mixed together.

10. The light emitting device of claim 1 wherein the n different red phosphor compositions are physically separated.

11. The light emitting device of claim 1 wherein x_m ranges from about 0.40 to about 0.90.

12. The light emitting device of claim 1 wherein values of x_m differ from adjacent values thereof by an amount Δ

x ranging from about 0.01 to about 0.5.

13. The light emitting device of claim 12 wherein the amount Δ

x ranges from about 0.05 to about 0.2.

14. The light emitting device of claim 1 wherein values of the peak emission wavelength λ

_m differ from adjacent values thereof by an amount Δ

λ

ranging from about 1 nm to about 20 nm.

15. The light emitting device of claim 14 wherein the amount Δ

λ

ranges from about 5 nm to about 10 nm.

16. The light emitting device of claim 1 wherein y ranges from about 0.005 to about 0.02.

17. The light emitting device of claim 16 wherein y is about 0.015.

18. The light emitting device of claim 1 wherein y=y_m each of the different red phosphor compositions comprising a different amount of Eu.

19. The light emitting device of claim 1 wherein the light emission spectrum is optimized for promoting photosynthesis.

20. The light emitting device of claim 19 wherein n=2, x₁=0.45, and x₂=0.85.

21. The light emitting device of claim 1 further comprising a green LED comprising light emission in a wavelength range from about 510 nm to about 580 nm, the light emission spectrum thereby further comprising a green spectral component.