Optical manifold for light-emitting diodes

• US 7,286,296 B2
• Filed: 04/25/2005
• Issued: 10/23/2007
• 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): Harrington; Alicia M
• Application Number:
  US11/115,055
• Publication Number:
  US 20050243570A1
• Time in Patent Office: 911 Days
• Field of Search: 359/641, 359/720, 359708-712, 362/84, 362/222, 362/268, 362/335, 362/341, 362346-347
• US Class Current: 359/641
• CPC Class Codes: F21K 9/61 using light guides
• CPC Class Codes: F21S 41/00 Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps reversing lights F21S43/00
• CPC Class Codes: F21S 41/125 Coloured light
• CPC Class Codes: F21S 41/141 Light emitting diodes [LED]
• CPC Class Codes: F21S 41/143 the main emission direction of the LED being parallel to the optical axis of the illuminating device
• CPC Class Codes: F21S 41/151 arranged in one or more lines
• CPC Class Codes: F21S 41/153 arranged in a matrix
• 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-F21S41/28
• CPC Class Codes: F21S 41/323 the reflector having two perpendicular cross sections having regular geometrical curves of a distinct nature
• CPC Class Codes: F21S 41/333 with discontinuity at the junction between adjacent areas
• CPC Class Codes: F21S 43/251 the light guides being used to transmit light from remote light sources
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 19/0023 at least one surface having optical power
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0066 : in the form of an LED array
• CPC Class Codes: G02B 27/0994 : Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 3/0056 : arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• 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 6/0046 : 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 LED outputs into a single, substantially homogeneous output, in a small, cost-effective package. The optical manifolds can be used to combine multiple LEDs of the same color and provide a high intensity output aperture with very high uniformity and sharp borders, or they can be used to generate a multiwavelength output, such as red, green, and blue LEDs that are combined to generate white light. Embodiments are also 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. The optical manifolds are designed to alleviate substantial luminance inhomogeneities inherent to LEDs. The optical manifold utilizes principles of non-imaging optics to transform light and provide directed, substantially uniform light sources.

Claims

1. A multiwavelength light source comprising:

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

an optical filter that transmits light about a prescribed wavelength and reflects other wavelengths;

an input collimating optical system that directs light from said at least one LED 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 in response to excitation from light generated by said LEDs, said phosphor patch also being transinissive to light from said LED; and

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

2. The multiwavelength light source of claim 1 wherein said optical filter comprises one of a bandpass filter and a shortpass filter.

3. The multiwavelength light source of claim 1 wherein:

said input collimating system comprises a two stage collimator that includes a stage one collimating angle transformer, comprising a transparent material having a higher index of refraction than the stage two collimator, said stage one collimator being coupled to at least one LED.

26. A multiwavelength light source according to claim 1, wherein the output optical system configured as a concentrator comprises a concentrator that is etendue-limited from the short-pass filter to the phosphor patch.

27. A multiwavelength light source according to claim 26, wherein the etendue-limited concentrator comprises a concentrator selected from the group consisting of parabolic concentrators and elliptical concentrators.

28. A multiwavelength light source according to claim 26, wherein the etendue-limited concentrator comprises a compound parabolic concentrator.

4. A multiwavelength light source comprising:

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

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

a nonimaging output concentrator comprising a dielectric material, 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 the input collimators and the output concentrator, said sbortpass filter transmitting light below a prescribed wavelength and reflecting light above a prescribed wavelength; and

a phosphor patch formed on said exit port, said phosphor having a composition that luminesces in response to excitation from light generated by said LEDs, said phosphor patch also being partially transinissive to light from said LEDs.

5. The multiwavelength light source of claim 4 wherein:

said LEDs emit a blue color light;

said shortpass filter comprises a blue-pass filter; and

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

6. The multiwavelength light source of claim 4 wherein said noniniaging devices in the input optical system comprise at least one of a compound parabolic concentrator.

7. The multiwavelength light source of claim 4 wherein said nonimaging collimators and collimators are cross-CPCs tat have an approximately square cross section along their length.

8. The multiwavelength light source of claim 7 wherein said plurality of said collimators are ranged in a square configuration.

9. The multiwavelength light source of claim 8 wherein said output concentrator has an approximately square cross-section along its length.

10. The multiwavelength light source of claim 4 wherein said LEDs comprise immersed LEDs.

11. The multiwavelength light source of claim 4 wherein:

said plurality of LEDs comprise a first plurality of LEDs that emit approximately at said first dominant wavelength, and a second plurality of LEDs that emit approximately about a second dominant wavelength, and further comprising;

a dual shortpass filter at the interface between the input optical system and the output optical system, said dual shortpass filter transmitting light below a first and a second prescribed wavelengths; and

said phosphor has a composition that luminesces in response to excitation by at least one of said first and second wavelengths.

12. An optical manifold for distributing light, comprising:

a transparent body defining on outer surface, at least one entry port, and at least one exit port, said transparent body comprising a material suitable for propagating light, said material having an index of refraction suitable for providing total internal reflection at the surface of said body;

said outer surface comprising optically active surfaces angled for total internal reflection of light issuing into and out of said entry and exit ports;

said entry and exit ports operable for light-transmittance at substantially all incidence angles up to the critical angle of said material;

said entry and exit ports comprising a plurality of small ports acting in parallel and one large port optically connected to said plurality of small ports;

said optically active surfaces operable as connecting surfaces between said plurality of ports and

said single port;

said connecting surfaces operable for conveying light by total internal reflection at all incidence angles past the critical angle of said transparent material; and

said connecting surfaces comprising nonimaging configurations that spatially mix said light.

13. The system of claim 12 wherein said transparent body defines a plurality of small nonimaging transformers connected to said plurality of small ports and a large nonimaging transformer connected to said large port, said plurality of nonimaging concentrators spatially arrayed to connect to said large noniniaging transformer.

14. The system of claim 13 wherein said nonimaging optical transformer comprises at least one of a collimator, a concentrator, and an angle-rotator.

15. The system of claim 13 wherein said nonimaging optical transformer comprises at least one of a collimator, a concentrator, and a luminance shifter.

16. The system of claim 13 wherein said nonimaging optical collimator comprises an SMS optic.

17. The system of claim 13 wherein said nonimaging optical concentrator comprises an SMS optic.

18. The system of claim 13 further comprising a plurality of LEDs connected to said plurality of small ports so tat said plurality of small ports define a corresponding plurality of entry apertures, and said plurality of small nonimaging transformers comprise a plurality in an arry configuration, said plurality of small ports arranged to optically couple respectively with said plurality of LEDs.

19. The system of claim 12 further comprising a high index transparent material surrounding said transparent body proximate to said entry port, said high index transparent material having an index of refraction higher than said material of said transparent body.

20. The system of claim 12 wherein said plurality of small ports are spatially separated and said connecting surfaces comprise a branching structure defined by separate light channels issuing from a single channel optically connected to said single large port.

21. The system of claim 12 further comprising:

a plurality of LEDs of different colors connected to said plurality of small ports so that said plurality of small ports receive light of different colors; and

a plurality of wavelength-dependent filters arranged to combine the light from the plurality of small ports at the plurality of wavelengths into a single multiwavelength beam.

22. The system of claim 12 wherein said plurality of small ports comprise circularly symmetric TIR lenses adjacently arrayed hexagonally and said single large port comprises a single large circularly symmetric TIR lens optically coupled to said small TIR lenses.

23. An N:

1 optical manifold, where N is an integer having a value of two or greater, comprising;

N LEDs tat generate light said LEDs arranged in an approximately coplanar configuration;

N coplanar input ports optically coupled, respectively to said N LEDs;

N angle rotators connected respectively to said input ports;

an output manifold coupled to said angle rotators to receive the collective light propagated from said LEDs and through said angle rotators;

an exit port on said output manifold, said angle rotators arranged with respect to said output port to direct light approximately toward said output port; and

a plurality of slits, each slit formed proximate to its respective angle rotator to provide total internal reflection at the intersection between said LEDs and said angle rotators and direct the ligbt output from the angle rotators toward the exit port.

24. The N:

1 optical manifold of claim 23 wherein an air gap is defined between each of said LEDs and said angle rotators, so that within said manifold the light is confined within a critical angle for total internal reflection.

25. A triplex optical manifold for collecting and emitting light from a first, second, and third LED comprising:

a first luminance shifter having an input port connected to the first LED and an exit aperture on its opposite end;

a second luminance shifter having an input port connected to the second LED, and an exit aperture on its opposite end;

a luminance duct arranged between said first and second luminance shifters, said luminance duct having an input port connected to the third LED, said luminance duct having a configuration selected to output light from its exit aperture with an exit angle approximately equal to the light from the exit apertures of said first and second Luminance shifters;

an output manifold coupled to receive the light output from said luminance shifters and said luminance duct;

said first and second luminance shifters and said luminance duct arranged in a converting, non-parallel configuration, and so that their exit apertures converge to said output manifold; and

an output port on said output manifold.