Optical manifold for light-emitting diodes

• US 7,380,962 B2
• Filed: 01/11/2006
• Issued: 06/03/2008
• Est. Priority Date: 04/23/2004
• Status: Active Grant

• Current Assignee: Seoul Semiconductor Co., Ltd.
• Original Assignee: Light Prescriptions Innovators, LLC
• Inventors: Chaves, Julio C., Dross, Oliver, Parkyn, William A. Jr., Falicoff, Waqidi, Benitez, Pablo, Alvarez, Roberto, Minano, Juan C.
• Primary Examiner(s): Lee; Y My Quach
• Assistant Examiner(s): MACCHIAROLO, LEAH SIMONE
• Application Number:
  US11/329,294
• Publication Number:
  US 20060239006A1
• Time in Patent Office: 874 Days
• Field of Search: 362/293, 362/84, 362/268, 362/346, 362/230, 362/231, 359/722
• US Class Current: 362/293
• CPC Class Codes: F21K 9/61 using light guides
• CPC Class Codes: F21S 41/141 Light emitting diodes [LED]
• CPC Class Codes: F21S 41/16 Laser light sources
• CPC Class Codes: F21S 41/176 Light sources where the light is generated by photoluminescent material spaced from a primary light generating element
• CPC Class Codes: F21S 41/18 Combination of light sources of different types or shapes
• CPC Class Codes: F21S 41/24 Light guides
• CPC Class Codes: F21S 41/285 Refractors, transparent cover plates, light guides or filters not provided in groups F21S41/24 - F21S41/2805
• CPC Class Codes: F21S 45/47 Passive cooling, e.g. using fins, thermal conductive elements or openings
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2113/10 of different colours
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/095 Refractive optical elements
• CPC Class Codes: G02B 27/0983 being curved
• CPC Class Codes: G02B 27/1066 for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view
• CPC Class Codes: G02B 27/123 The splitting element being a lens or a system of lenses, including arrays and surfaces with refractive power
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0028 : Light guide, e.g. taper
• CPC Class Codes: G02B 6/0046 : Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0068 : Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 : Light emitting diode [LED]
• 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
• CPC Class Codes: H01L 33/60 : Reflective elements

Abstract

An optical manifold for efficiently combining a plurality of blue LED outputs to illuminate a phosphor for a single, substantially homogeneous output, in a small, cost-effective package. Embodiments are disclosed that use a single or multiple LEDs and a remote phosphor, and an intermediate wavelength-selective filter arranged so that backscattered photoluminescence is recycled to boost the luminance and flux of the output aperture. A further aperture mask is used to boost phosphor luminance with only modest loss of luminosity. Alternative non-recycling embodiments provide blue and yellow light in collimated beams, either separately or combined into white.

Claims

1. A multiwavelength light source comprising:

at least one light source that emits light at a dominant wavelength;

an optical filter that transmits light of prescribed wavelengths and reflects other wavelengths;

an input collimating optical system that directs light from said at least one light source through said optical filter;

an output optical system coupled to receive said light throughput from said optical filter, said output optical system configured as a concentrator and having an exit port on the opposite end;

a phosphor patch formed on said exit port, said phosphor having a composition that luminesces, emitting light of wavelengths reflected by said filter in response to excitation from light generated by said at least one light source; and

said phosphor patch having two surfaces, an inside surface receiving light from said output optical system and an opposing outside surface,

wherein said phosphor patch is transmissive to light from said at least one light source and so that said outside surface of said phosphor patch is operable as an emitter of said light source, and

wherein said output optical system has a shape that approximately collimates backscattered luminescence from said phosphor patch by directing said backscattered luminescence to said optical filter from which it is reflected back to said exit port.

2. The multiwavelength source of claim 1, wherein said at least one light source comprises at least one light emitting diode.

3. The multiwavelength source of claim 1 wherein said phosphor patch comprises a composite material comprising a phosphor layer deposited on a suitable transparent substrate;

and

said composite material is optically coupled to said exit port of said optical output system.

4. The multiwavelength source of claim 3 wherein said composite material is cut from a large composite sheet.

5. The multiwavelength light source of claim 1, wherein said phosphor patch has a thin edge and wherein the edge and part of said outside surface of said phosphor patch are masked by a reflecting wall with reflectance above 90%.

6. The multiwavelength light source of claim 5 wherein said reflecting wall is operable for increasing the luminance of the light source by said masking of said outside surface causing recycling of the masked light into the remaining clear aperture.

7. The multiwavelength light source of claim 5 wherein said output face over said phosphor patch has an irregularly shaped border.

8. The multiwavelength light source of claim 7 wherein said irregularly shaped border is in the shape of an automotive headlamp beam pattern.

9. The multiwavelength light source of claim 5 wherein said phosphor patch is a composite material comprising a phosphor layer deposited on a suitable transparent substrate;

and said composite material is optically coupled to said exit port of said optical output system.

10. The multiwavelength light source of claim 9 wherein said composite material is cut from a large composite sheet.

11. The multiwavelength light source of claim 1 wherein said phosphor patch is provided with a heat sink.

12. The multiwavelength light source of claim 1, wherein said output concentrator is a nonimaging output concentrator and is circularly symmetric, with said collective reception of light output from said input collimators having an acceptance angle equal to the extreme diagonal of said light output.

13. The multiwavelength light source of claim 1,

wherein said output optical system comprises a conicoid reflector wilt high specular reflectance on its interior surface and a plano-convex lens or lenslet array, with said plano face accepting light from said filter.

14. The multiwavelength light source of claim 13 where said conicoid reflector is provided with heat sink.

15. The multiwavelength light source of claim 1 wherein:

said at least one light source comprises at least one LED that emits blue light;

said optical filter comprises a shortpass blue filter; and

said phosphor patch having a composition that emits longer-wavelength luminescence in response to said excitation by said blue light generated by said LEDs, the spectral distribution of said luminescence metamerically combining with said blue light to provide an approximately white light source.

16. A multiwavelength light source comprising:

a plurality of LEDs that emit light at and about a dominant wavelength;

a plurality of nonimaging input collimators comprising a dielectric material, each input collimator connected respectively to one of said plurality of LEDs;

a nonimaging output concentrator, said output concentrator coupled to collectively receive the light output from each of said input collimators on one end, said output concentrator having an exit port on the opposite end;

a shortpass filter at the interface between said input collimators and said output concentrator, said shortpass filter transmitting light of wavelengths less than a prescribed wavelength and reflecting light of wavelengths greater than a prescribed wavelength; and

a phosphor patch formed on said exit port, the material of said phosphor patch having a composition that luminesces in response to excitation from light generated by said LEDs,

wherein said phosphor patch has an inside surface receiving light from said output optical system and an opposing outside surface, and

wherein said phosphor patch is also partially transmissive to light from said LEDs, so that said outside surface of said phosphor patch comprises the emitter of said light source.

17. The multiwavelength light source of claim 16 wherein said phosphor patch has non-uniform thickness.

18. The multiwavelength light source of claim 16 wherein the edge and part of said emitter surface of said phosphor patch are masked by a reflecting wall with reflectance above 90%, forming an emitting exit face smaller than said emitter surface of said phosphor patch.

19. The multiwavelength light source of claim 18 wherein said exit face over said phosphor patch has an irregularly shaped border.

20. The multiwavelength light source of claim 19 wherein said irregularly shaped border is in the shape of an automotive headlamp beam pattern.

21. The multiwavelength light source of claim 16 wherein said phosphor patch comprises a composite material comprised of a phosphor material deposited on a suitable transparent substrate.

22. The multiwavelength source of claim 21 wherein said composite material is cut from a large composite sheet.

23. The multiwavelength light source of claim 16 wherein said phosphor patch is provided with a heat sink.

24. The multiwavelength light source of claim 16 wherein said phosphor patch has non-uniform thickness.

25. The multiwavelength light source of claim 16, wherein said nonimaging output concentrator is circularly symmetric, with said collective reception of light output from said input collimators having an acceptance angle equal to the extreme angular diagonal of said light output.

26. The multiwavelength light source of claim 16, wherein said output optical system comprises a conicoid reflector with high specular reflectance on its interior surface and a plano-convex lens or lenslet array, with said plano face accepting light from said filter.

27. The multiwavelength light source of claim 16 wherein:

said LEDs emit blue light;

said shortpass filter comprises a blue-pass filter; and

said material of said phosphor patch having a composition that emits approximately yellow luminescence in response to said excitation by said blue light generated by said LEDs, thereby providing an approximately white light source.

28. A multiwavelength light source comprising:

at least one LED that emits light at a dominant wavelength;

an input optical system coupled to said at least one LED and collimating its light;

one or more mirrors that direct a first part of the collimated light from the input optical system to an output port, and directs a second part of the collimated light from the input optical system to an intermediate optical system, said intermediate optical system configured as a concentrator and having an exit port on the opposite end; and

a phosphor patch formed on said exit port, the material of said phosphor patch having a composition that luminesces in response to excitation from light generated by said LEDs, light emitted by said phosphor patch being returned back through and out of said intermediate optical system, to an output port.

29. The multiwavelength light source of claim 28, wherein said phosphor patch has a thin edge and two surfaces, an inside surface receiving light from said intermediate optical system and an opposing outside surface;

said phosphor patch also being transmissive to light from said LED; and

a highly reflective surface covering said outside surface of said phosphor patch, causing light that would have been emitted by said outside surface of said phosphor patch to instead be returned along with light emitted by said inside surface back through and out of said intermediate optical system.

30. The multiwavelength light source of claim 29 wherein said reflective surface is provided with a heat sink.

31. The multiwavelength light source of claim 28,

wherein said one or more mirrors comprise one or more inclined optical filters that reflect collimated light from said input optical system of wavelengths less than a prescribed wavelength and transmit longer wavelengths to an output port, said prescribed wavelength lying within the spectrum of said LED so that said filters act as a spectral beamsplitter;

wherein said intermediate optical system returns said emitted light to said one or more optical filters; and

further comprising one or more all-wavelength mirrors that redirect emitted light received from said one or more optical filters to said output port.

32. The multiwavelength light source of claim 28 wherein light is output as two or more spatially separated beams comprising two or more spectral bands.

33. The multiwavelength light source of claim 28, wherein said mirrors comprise:

one or more inclined optical filters that partially transmits light of wavelengths less than a prescribed wavelength to said output port and partially reflects shorter wavelengths and transmits longer wavelengths, said partial transmission and reflection wavelengths lying within the spectrum of said LED so that said filter acts as a spectral beamsplitter and

one or more inclined optical short-pass filters that transmits light of wavelengths less than a prescribed wavelength and reflects light of longer wavelengths, and

wherein said emitted light is returned to one or more said inclined short-pass filters that reflect said emitted light to said output port.

34. The multiwavelength light source of claim 33 wherein said intermediate optical system also comprises at least one of a folding mirror and one or more mirrors for redirecting shorter wavelength light not reflected by said short-pass filters back to said phosphor patch.

35. The multiwavelength light source of claim 28 wherein said LED and said phosphor patch lie approximately on the same plane.

36. The multiwavelength light source of claim 28, wherein:

said one or more mirrors comprise one or more inclined optical filters that partially transmit and partially reflect light shorter than a prescribed wavelength;

said prescribed wavelength lies within the spectrum of said LED so that said filter acts as a spectral beamsplitter;

said filter is transmissive to longer wavelengths than said prescribed wavelength and allowing said partially transmitted light to be directed to a short-wavelength said output port;

said intermediate optical system comprises one or more inclined long-pass filters;

said emitted light is returned to said long-pass filters; and

said long-pass filters are transmissive to said emitted light and directing said light to a long-wavelength output port.

37. The multiwavelength light source of claim 28, wherein:

said one or more mirrors comprise one or more inclined optical mirrors, said mirrors reflecting said light to one or more spectrally beam-splitting filters, said filters partially transmitting and partially reflecting said light shorter than a prescribed wavelength;

said prescribed wavelength lies within the spectrum of said LED so that said filter acts as a spectral beam splitter within said spectrum;

said filters are transmissive to longer wavelengths than said prescribed wavelength and allowing said partially reflected light to be directed to an output port;

said source further comprises one or more inclined optical short-pass filters that transmits light of wavelengths less than a prescribed wavelength and reflects light of longer wavelengths,

said intermediate optical system comprises one or more inclined mirrors;

light emitted by said phosphor patch is returned to said short-pass filters; and

said short-pass filters are reflective to said emitted light and directing said light to said output port.

38. The multiwavelength light source of claim 28 wherein said input collimating system and said intermediate optical system lie on a common axis.

39. The multiwavelength light source of claim 28 wherein said output port can be rotated about an axis.

40. The multiwavelength source of claim 39, wherein said first part of said light and said emitted light enter said rotatable output port along said axis of rotation.

41. The multiwavelength light source of claim 28, comprising:

wherein said one or more mirrors comprise one or more inclined optical mirrors that reflect a fraction of said light to one or more long-pass filters;

said long-pass filters reflecting light shorter than a prescribed wavelength to said outport port;

wherein said prescribed wavelength lies within the spectrum of said LED and said filters are transmissive to longer wavelengths than said prescribed wavelength;

said intermediate optical system coupled to receive the remainder of the light reflected from said inclined optical mirrors;

said intermediate optical system comprising one or more long-pass filters that reflect said remainder of light from said inclined mirrors to said exit port;

light emitted by said phosphor patch being returned to said long-pass filters;

wherein said long-pass filters are transmissive to said emitted light and direct said emitted light to said output port.

42. The multiwavelength light source of claim 28, wherein said input collimating optical system has an acceptance angle smaller than said intermediate optical system.

43. The multiwavelength light source of claim 28 wherein one or more diffusers widen the beam divergence angle of said first part of said light.

44. The multiwavelength light source of claim 28 wherein at least one of said input optical system and said intermediate optical system has one or more said concentrators whose cross-section is rectangular.

45. The multiwavelength light source of claim 28,

wherein said one or more mirrors comprise one or more filters that partially transmit and partially reflect said light shorter than a prescribed wavelength;

wherein

said prescribed wavelength lies within the spectrum of said LED so that said filters act as a spectral beamsplitter; and

said spectral beamsplitters being reflective to longer wavelengths than said prescribed wavelength and angled so as to direct said partially transmitted light to one or more diffusers, said diffusers widening the beam divergence angle of said partially transmitted light, said beam directed to one or more short-pass filters;

wherein said short-pass filters are transmissive and direct said light to an output port;

said intermediate optical system comprising one or more inclined long-pass filters;

light emitted by said phosphor patch being returned to said long-pass filters;

wherein said long-pass filters are transmissive to said emitted light and direct said emitted light to one or more secondary folding mirrors;

wherein said secondary folding mirrors redirect emitted light to said short-pass filters, said short-pass filters reflecting said emitted light to said output port.

46. The multiwavelength source of claim 28 wherein said LED is an array of LEDs and said exit port is an array of exit ports and said phosphor patch is an array of phosphor patches.

47. The multiwavelength light source of claim 28,

wherein said one or more mirrors comprises one or more optical mirrors that redirects a portion of said collimated light to said output port;

said intermediate optical system comprising one or more inclined short-pass filters;

said phosphor patch being transmissive to light from said LED;

light emitted by said phosphor patch being returned to said short-pass filters;

wherein said short-pass filters are reflective to said emitted light and directing said light to said output port.

48. The multiwavelength light source of claim 47 wherein said output port includes both a short-wave output port and a long-wave output port.

49. The multiwavelength light source of claim 28 wherein said LED and said phosphor patch lie on approximately the same axis.

50. The multiwavelength light source of claim 28,

wherein said input collimating optical system directs a fraction of light from said at least one LED through a short-wave output port;

wherein said intermediate optical system comprises one or more inclined long-pass filters for redirecting reflected light from said one or more mirrors;

light emitted by said phosphor patch being returned to said long-pass filters which transmits said emitted light to a long-wave output port contiguous with said short-wave output port.

51. The multiwavelength light source of claim 28 wherein said LED and said phosphor patch is provided with a heat sink.

52. The multiwavelength light source of claim 28, further comprising:

a second at least one LED that emits light at a dominant wavelength; and

a second input optical system directing light from said second at least one LED and collimating said light through one or more said mirrors;

wherein said one or more mirrors transmits collimated light from said second LED to said intermediate optical system.

53. The multiwavelength light source of claim 52, wherein the proportion of said first part of said light to said second part of said light from said at least one LED is different from the proportion of said first part of said light to said second part of said light from said second at least one LED.

54. The multiwavelength light source of claim 52 operable as a variable color temperature source.

55. The multiwavelength source of claim 52 wherein said first LEDs is an array of LEDs, said second LEDs is an array of LEDs, said exit port is an array of exit ports and said phosphor patch is an array of phosphor patches.

56. The multiwavelength light source of claim 55 wherein:

said array of phosphor patches comprise one or more green phosphor patches;

said first or second array of LEDs comprises one or more red LEDs; and

for each red LED in said first array of LEDs, said mirrors receiving light from said red LEDs are long-pass filters that transmit red light from said one or more red LEDs and reflect light from said one or more phosphor patches of green phosphor to said output port.

57. The multiwavelength light source of claim 52 wherein said first and second LEDs and said phosphor patch is provided with a heat sink.

58. The multiwavelength light source of claim 52,

wherein said one or more mirrors comprises one or more inclined short-pass optical filters that transmits said collimated light for wavelengths less than a prescribed wavelength to said output port, said prescribed wavelength lying within the spectrum of said LED;

wherein said one or more inclined short-pass optical filters transmits collimated light from said second LED of wavelengths less than a prescribed wavelength to said intermediate optical system, said prescribed wavelength lying within the spectrum of said second at least one LED; and

wherein light emitted by said phosphor patch is returned to one or more said inclined short-pass filters that are reflective to said emitted light and that direct said emitted light to said output port.

59. The multiwavelength light source of claim 52, wherein

said one or more mirrors comprises one or more inclined short-pass optical filters that transmits said collimated light for wavelengths less than a prescribed wavelength to said output port, said prescribed wavelength lying within the spectrum of said LED;

said second input optical system collimating said light to one or more inclined long-pass optical filters;

said one or more inclined long-pass optical filters reflecting collimated light of wavelengths less than a prescribed wavelength lying within the spectrum of said second at least one LED to one or more all-wavelength folding mirrors;

said all-wavelength folding mirror reflecting said collimated light to said intermediate optical system;

light emitted by said phosphor patch being returned to one or more of said all-wavelength folding mirrors that direct said emitted light to said inclined short-pass filters which reflects said emitted light to a said output port.

60. The multiwavelength source of claim 52, wherein

said one or more mirrors comprises one or more inclined short-pass optical filters that transmits said collimated light for wavelengths less than a prescribed wavelength to said output port, said prescribed wavelength lying within the spectrum of said LED;

said second input optical system collimating said light from said second at least one LED to one or more inclined all-wavelength folding mirrors;

said one or more inclined all-wavelength folding mirrors reflecting collimated light of wavelengths less than a prescribed wavelength lying within the spectrum of said second at least one LED to one or more further all-wavelength folding mirrors;

said further all-wavelength folding mirrors reflecting said collimated light to said intermediate optical system;

light emitted by said phosphor patch being returned to one or more of said further all-wavelength folding mirrors that direct said emitted light to said inclined short-pass filters which reflects said emitted light to a said output port.

61. The multiwavelength light source of claim 28 configured for partial recycling and partial non-recycling.

62. The multiwavelength light source of claim 61 wherein said inclined short-pass optical filter is triangular in cross-section.

63. The multiwavelength light source of claim 28, wherein said one or more mirrors comprises a mirror positioned to reflect part of said collimated light and to be missed by another part of said collimated light.