Warm white lighting device
View Patent ↗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.
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 assay is configured to include a predetermined factor randomizing a surface shape of lenslets within at least one of the first micro-lenslet arsay and the second micro-lenslet array that improves the homogenization of the warn 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.
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 warn 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 wasm 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.
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.