Side emitting illumination systems incorporating light emitting diodes

• US 7,293,908 B2
• Filed: 10/18/2005
• Issued: 11/13/2007
• Est. Priority Date: 10/18/2005
• Status: Expired due to Fees

• Current Assignee: Goldeneye, Inc.
• Original Assignee: Goldeneye, Inc.
• Inventors: Beeson, Karl W., Zimmerman, Scott M.
• Primary Examiner(s): Cariaso; Alan
• Assistant Examiner(s): MACCHIAROLO, LEAH SIMONE
• Application Number:
  US11/253,174
• Publication Number:
  US 20070086211A1
• Time in Patent Office: 756 Days
• Field of Search: 362/612, 362296-298, 362/613, 362/609, 362/555, 362/301, 362/300, 362/241, 362/230, 362/800, 257/98, 257/99, 257/290
• US Class Current: 362/612
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• 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 33/60 Reflective elements
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

The invention is a side-emitting illumination system that incorporates a light emitting diode. The side-emitting illumination system recycles a portion of the light internally generated by a light emitting diode back to the light emitting diode as externally incident light. The light emitting diode reflects the recycled light, thereby increasing the effective brightness of the light emitting diode. The light reflected by the light emitting diode is directed though the output aperture of the side-emitting illumination system, thereby increasing the output brightness and efficiency of the side-emitting illumination system. The light emitting diode reflects externally incident light with a reflectivity greater than 40 percent.

Claims

1. An side-emitting illumination system, comprising:

a light emitting diode having

a first doped semiconductor layer having an output surface;

a second doped semiconductor layer, said second doped semiconductor layer and said first doped semiconductor layer having opposite n and p conductivity types;

an active region interposed between said first doped semiconductor layer and said second doped semiconductor layer, said active region in electrical contact with said first doped semiconductor layer and said second doped semiconductor layer;

a first reflecting electrode in electrical contact with said first doped semiconductor layer;

a second reflecting electrode in electrical contact with said second doped semiconductor layer;

a first reflector surrounding said light emitting diode;

a second reflector separated from and opposing said first reflector and said light emitting diode and said second reflector having an edge;

an output aperture formed by said first reflector and by said edge of said second reflector;

a supporting means which holds and separates said second reflector from said first reflector;

wherein said active region of said light emitting diode emits internally generated light through said output surface of said first doped semiconductor layer when a voltage is applied between said first reflecting electrode and said second reflecting electrode;

wherein said internally generated light emitted through said output surface of said first doped semiconductor layer is directed to said second reflector or is directed through said output aperture;

wherein said internally generated light reflected by said second reflector is redirected through said output aperture or is redirected to said first reflector or is recycled back to said light emitting diode as externally incident light; and

wherein a portion of said externally incident light recycled back to said light emitting diode is reflected by said first reflecting electrode and said second reflecting electrode of said light emitting diode, thereby increasing the effective brightness of said light emitting diode, and is directed through said output aperture, thereby increasing the output brightness and efficiency of said side-emitting illumination system.

2. A side-emitting illumination system as in claim 1, wherein said second reflector is a diffuse reflector.

3. A side-emitting illumination system as in claim 1, wherein said second reflector is a specular reflector.

4. A side-emitting illumination system as in claim 2, wherein said second reflector is a substantially planar surface.

5. A side-emitting illumination system as in claim 4, wherein the separation distance between said second reflector and said first reflector is less than 5 millimeters.

6. A side-emitting illumination system as in claim 5, wherein the separation distance between said second reflector and said first reflector is less than 2 millimeters.

7. A side-emitting illumination system as in claim 2, wherein said second reflector is an inverted peak or is curved, wherein the separation distance between said second reflector and said first reflector increases from the center of said second reflector to said edge of said second reflector.

8. A side-emitting illumination system as in claim 1, further comprising a waveguide, wherein said waveguide has an input surface that substantially spans said output aperture, wherein said waveguide transmits through said input surface said internally generated light from said output surface of said light emitting diode, said internally generated light reflected by said second reflector and said externally incident light reflected from said first reflecting electrode and said second reflecting electrode of said light emitting diode and wherein said waveguide transmits light by total internal reflection.

9. A side-emitting illumination system as in claim 8, wherein said waveguide further includes light extracting elements that extract light from said waveguide to be transmitted out of said waveguide.

10. A side-emitting illumination system as in claim 8, wherein said waveguide is a flexible waveguide.

11. A side-emitting illumination system as in claim 10, wherein said flexible waveguide is a plurality of said flexible waveguides.

12. A side-emitting illumination system as in claim 1, wherein said light emitting diode is a plurality of said light emitting diodes.

13. A side-emitting illumination system as in claim 12, wherein said plurality of said light emitting diodes emit more than one color of light.

14. A side-emitting illumination system as in claim 1, wherein said light emitting diode reflects said externally incident light with a reflectivity greater than 40 percent.

15. A side-emitting illumination system as in claim 14, wherein said light emitting diode reflects said externally incident light with a reflectivity greater than 50 percent.

16. A side-emitting illumination system as in claim 15, wherein said light emitting diode reflects said externally incident light with a reflectivity greater than 60 percent.

17. A side-emitting illumination system as in claim 1, wherein said supporting means is a transparent material spanning the region between said second reflector and said first reflector and wherein said supporting means surrounds said light emitting diode.

18. A side-emitting illumination system as in claim 1, further comprising a wavelength conversion layer that converts a portion of the internally generated light of a first color into light of a second color, different than said first color.

19. A side-emitting illumination system as in claim 18, wherein said wavelength conversion layer is disposed on said output surface of said light emitting diode.

20. A side-emitting illumination system as in claim 18, wherein said wavelength conversion layer is disposed on said second reflector.

21. A side-emitting illumination system as in claim 18, wherein said wavelength conversion layer spans the region between said second reflector and said first reflector.

22. A side-emitting illumination system as in claim 1, wherein said first reflector is a specular reflector.

23. A side-emitting illumination system as in claim 1, wherein said first reflector is a diffuse reflector.