WARM WHITE LIGHTING DEVICE

• US 20110051394A1
• Filed: 09/10/2008
• Published: 03/03/2011
• Est. Priority Date: 09/10/2007
• 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
• Granted Patent: US 8,231,250 B2
• Time in Patent Office: Days
• US Class Current: 362/84
• CPC Class Codes: F21K 9/68 Details of reflectors forming part of the light source
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21V 9/02 for simulating daylight F21V9/04, F21V9/06 take precedence
• 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 33/58 Optical field-shaping elements

Abstract

The present invention relates to warm white light engines including combinations of blue, cyan, and red, red-orange, or amber emitters and one or more phosphors that produce a white light pleasing to the human eye through the use of improved color uniformity and improved collimation of light. Specifically, a micro-lenslet array having an optimized surface is used to disperse light from the light emitter; an innercollimation lens having an optimized cross-sectional shape and micro-ridges is used to disperse light; a TIR reflector having an optimized cross-sectional shape and micro-ridges is used to disperse and redistribute phase as well as provide collimation; and a final micro-lenslet layer includes optimized lenslet design placement and randomization factor to homogenize light to produce a uniform warm white light.

Claims

1. An apparatus for producing improved warm white light, comprising:

a light collimation lens configured to receive light from a light engine and to produce collimated light;

a first micro-lenslet array disposed to receive at least a portion of the collimated light to produce dispersed light;

a ribbed reflector disposed to reflect at least a portion of the dispersed light and the collimated light to produce reflected light; and

a second micro-lenslet array disposed to receive at least a portion of the reflected light to produce warm white light having improved collimation and mixing characteristics.

2. The apparatus of claim 1, wherein at least one of the first micro-lenslet array and the second micro-lenslet array comprises at least one lenslet having a surface shape selected from the group consisting of radii, conic, aspheric, and Zernike.

3. The apparatus of claim 1, wherein at least one of the first micro-lenslet array and the second micro-lenslet array is configured to include a predetermined placement of lenslets within at least one of the first micro-lenslet array and the second micro-lenslet array that improves the homogenization of the warm white light.

4. The apparatus of claim 1, wherein at least one of the first micro-lenslet array and the second micro-lenslet array is configured to include a predetermined factor randomizing a surface shape of lenslets within at least one of the first micro-lenslet array and the second micro-lenslet array that improves the homogenization of the warm white light.

5. The apparatus of claim 1, wherein at least one of the first micro-lenslet array and the second micro-lenslet array is configured to produce an intermediate image at an upper surface of the respective lenslet dielectric.

6. The apparatus of claim 1, wherein at least one of the first micro-lenslet array and the second micro-lenslet array is configured to produce an intermediate image within a respective lenslet dielectric.

7. The apparatus of claim 1, wherein at least one of the first micro-lenslet array and the second micro-lenslet array is configured to produce an intermediate image outside a respective lenslet dielectric.

8. The apparatus of claim 1, wherein the light collimation lens comprises an approximately barrel-shaped sidewall.

9. The apparatus of claim 8, wherein the sidewall is configured to have a spline-shaped vertical cross-section.

10. The apparatus of claim 8, wherein the sidewall comprises at least a first plurality of micro-ridges.

11. The apparatus of claim 10, wherein the first plurality of micro-ridges covers a portion less than a whole of the sidewall, and the sidewall further comprises at least a second plurality of micro-ridges, wherein the first plurality of micro-ridges and the at least second plurality of micro-ridges are non-overlapping.

12. The apparatus of claim 1, further comprising a light extraction lens directing light to the light collimation lens.

13. The apparatus of claim 1, wherein the ribbed reflector is configured to have a spline-shaped vertical cross-section.

14. The apparatus of claim 13, wherein the ribbed reflector comprises at least a first plurality of micro-ridges.

15. The apparatus of claim 14, wherein the first plurality of micro-ridges covers a portion less than a whole of the ribbed reflector, and the ribbed reflector further comprises at least a second plurality of micro-ridges, wherein the first plurality of micro-ridges and the at least second plurality of micro-ridges are non-overlapping.

32. The apparatus of claim 1, wherein the ribbed reflector comprises a sidewall having a plurality of micro-ridges vertically disposed thereon, wherein a cross-section of each micro-ridge comprises a pyramidal lens shape.

33. The apparatus of claim 1, wherein the light collimation lens comprises a sidewall having a plurality of micro-ridges vertically disposed thereon, wherein a cross-section of each micro-ridge comprises a pyramidal lens shape.

16. A system for producing improved warm white light, comprising:

a light engine;

a light collimation lens configured to receive light from the light engine and to produce collimated light;

a first micro-lenslet array disposed to receive at least a portion of the collimated light to produce dispersed light;

a ribbed reflector disposed to reflect at least a portion of the dispersed light and the collimated light to produce reflected light;

and a second micro-lenslet array disposed to receive at least a portion of the reflected light to produce warm white light having improved collimation and mixing characteristics.

17. The system of claim 16, wherein the light engine comprises:

a printed circuit board;

an interposer disposed on the printed circuit board;

a plurality of non-white solid state light emitters disposed on the interposer, the interposer configured to provide thermal conduction and strain relief for the light emitters; and

a reflector reflecting at least a portion of the light from the light emitters.

18. The system of claim 17, wherein the light engine further comprises a phosphor at least partially disposed over at least a portion of the plurality of non-white solid state light emitters.

19. The system of claim 18, wherein the phosphor is dispersed within an encapsulant overlying at least a portion of the plurality of non-white solid state light emitters.

20. The system of claim 18, wherein the phosphor is formed within a conformal coating overlying at least a portion of the plurality of non-white solid state light emitters.

21. The system of claim 18, wherein the phosphor is directly applied to at least a portion of the plurality of non-white solid state light emitters.

22. The system of claim 19. Wherein the phosphor is mixed with a high index silicone encapsulant.

23. The system of claim 20, wherein the phosphor comprises a powder settled within a clear silicone encapsulant bulk material.

24. A method for producing improved warm white light, comprising the following steps:

emitting light using a plurality of non-white solid state light emitters;

collimating at least a portion of the emitted light using a light collimation lens to produce collimated light;

dispersing at least a portion of the collimated light using a first micro-lenslet array to produce dispersed light;

reflecting at least a portion of the dispersed light and the collimated light using a ribbed reflector to produce reflected light; and

receiving at least a portion of the reflected light using a second micro-lenslet array to produce warm white light having improved collimation and mixing characteristics.

25. The method of claim 24, further comprising the step of converting the wavelength of at least a portion of the emitted light using a phosphor.

26. The method of claim 25, further comprising the step of disposing the phosphor at least partially over at least a portion of the plurality of non-white solid state light emitters.

27. The method of claim 26, wherein the step of disposing the phosphor further comprises the following steps:

mixing a phosphor powder by volume percent with a silicone-based material; and

encapsulating the plurality of non-white solid state light emitters with the mixed silicone-based material.

28. The method of claim 26, wherein the step of disposing the phosphor further comprises the following steps:

dispersing a phosphor powder into a silicone-based material;

encapsulating the plurality of non-white solid state light emitters with the mixed silicone-based material;

settling the phosphor powder within the silicone-based material; and

curing the silicone-based material.

29. The method of claim 26, wherein the step of disposing the phosphor further comprises the following steps:

applying a slurry containing the phosphor to the plurality of non-white solid state light emitters; and

curing the slurry.

30. The method of claim 26, wherein the step of disposing the phosphor further comprises the following steps:

applying a slurry containing the phosphor to the plurality of non-white solid state light emitters; and

applying an electric field to deposit the phosphor by electrophoresis.

31. The method of claim 25, wherein the phosphor is formed within a conformal coating overlying at least a portion of the plurality of non-white solid state light emitters.