Solid state lighting with selective matching of index of refraction

• US 8,322,884 B2
• Filed: 03/31/2010
• Issued: 12/04/2012
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Inventors: Ramer, David P., Rains, Jack C. Jr.
• Primary Examiner(s): Crowe, David
• Application Number:
  US12/751,169
• Publication Number:
  US 20110242806A1
• Time in Patent Office: 979 Days
• Field of Search: 362/26, 362/27, 362/608, 362/610, 362/612, 362/235, 362/242, 362/249.02, 362/311.02, 362/147
• US Class Current: 362/249.04
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

Where a lighting device uses solid state emitters and an optic processes light from the emitters, it may improve efficiency in light extraction from the emitters to have an index of refraction matching material in between emitter output and a surface of solid of the optic that receives emitted light. However, such improved out-coupling or extraction efficiency may cause an overall color shift in the output of the overall lighting device, for example, if improved emitter output reduces internal reflection and associated internal phosphor excitation. To reduce the color shift in the output of the lighting device, the device may have index matching material used in association with one or some of the solid state light emitters but not all of the emitters, so that the combined light output of the device exhibits a desired spectral characteristics, e.g. remains a desirable color of white light.

Claims

1. A solid state lighting device, comprising:

a plurality of solid state light emitters, each having a cover for protecting a light source positioned inside each solid state emitter, and each solid state light emitter configured for emitting light in a predetermined spectrum;

an optic, positioned outside of each cover of the solid state emitters, for combining light received from the plurality of solid state light emitters to form output light of the device,

wherein at least a portion of the optic for receiving light from the plurality of solid state light emitters is formed of a light transmissive solid having an index of refraction, and having a surface facing each cover of the plurality of solid state emitters; and

an index matching material positioned on a first region of the surface of the light transmissive solid, the index matching material for matching the index of refraction of the light transmissive solid, in an optical path between a light emission output of at least one first solid state light emitter and the first region of the surface of the light transmissive solid arranged to receive light from the at least one first solid state light emitter,

wherein at least one second solid state light emitter is coupled to supply light to the light transmissive solid without any index matching material in an optical path between a light emission output of the at least one second solid state light emitter and a second region of the surface of the light transmissive solid arranged to receive light from the at least one second solid state light emitter.

2. The solid state lighting device according to claim 1, further comprising a reflector having a diffusely reflective interior surface extending over at least a substantial portion of the outer surface of the light transmissive solid to form an optical cavity including the volume of the light transmissive solid, a portion of an aperture surface of the light transmissive solid forming an optical aperture of the cavity.

3. The solid state lighting device according to claim 1, further comprising a heat sink member having an inner peripheral portion of a size larger than an outer peripheral portion of the light transmissive solid and having an inner surface at an angle at least substantially corresponding to the angle formed by a peripheral optical coupling surface of the light transmissive solid.

4. The solid state lighting device according to claim 1, wherein at least one solid state light emitter further comprises a material for changing the wavelength of the light emitted from the light source in the optical path between the light emission output of at least one first solid state light emitter and a surface of the light transmissive solid.

5. The solid state lighting device according to claim 4, wherein the material for changing the wavelength of light comprises at least one phosphor.

6. The solid state lighting device according to claim 5, wherein the at least one phosphor is a yttrium aluminum garnet (YAG) phosphor.

7. The solid state lighting device according to claim 4, wherein the material for changing the wavelength of the emitted light substantially fills a region of the at least one solid state light emitter between the light source and the light transmissive solid.

8. The solid state lighting device according to claim 1, wherein the index matching material is deposited on the light transmissive solid.

9. The solid state lighting device according to claim 1, wherein the lighting device emits a substantially white light.

10. The solid state lighting device according to claim 1, wherein the fixture comprises a substantially equal number of first solid state light emitters and second solid state light emitters.

11. The solid state lighting device according to claim 1, wherein the index matching material comprises a silicone.

12. The solid state lighting device according to claim 1, in combination with circuitry for controlling operation of one or more of the plurality of solid state light emitters.

13. A solid state lighting device, comprising:

a plurality of solid state light emitters, each configured for emitting light in a predetermined spectrum;

an optic for combining light received from the plurality of solid state light emitters to form output light of the device, wherein at least a portion of the optic for receiving light from the plurality of solid state light emitters is formed of a light transmissive solid having an index of refraction; and

a heat sink member having an inner peripheral portion of a size larger than an outer peripheral portion of the light transmissive solid and having an inner surface at an angle at least substantially corresponding to the angle formed by a peripheral optical coupling surface of the light transmissive solid; and

a flexible circuit board, the flexible circuit board comprising;

(a) a mounting section mounted on the heat sink member, and

(b) a plurality of flexible tabs attached to and extending from the mounting section of the flexible circuit board, each flexible tab being bent around the heat sink member and positioned between the angled inner surface of the inner peripheral portion of the heat sink member and the angled peripheral optical coupling surface of the light transmissive solid,

an index matching material for matching the index of refraction of the light transmissive solid, in an optical path between a light emission output of at least one first solid state light emitter and each surface of the light transmissive solid arranged to receive light from the at least one first solid state light emitter, wherein;

at least one second solid state light emitter is coupled to supply light to the light transmissive solid without any index matching material in an optical path between a light emission output of the at least one second solid state light emitter and each surface of the light transmissive solid arranged to receive light from the at least one second solid state light emitter, and

each of the plurality of solid state light emitters is mounted on a tab of the flexible circuit board and positioned by the respective tab between the respective tab and the angled peripheral optical coupling surface of the outer peripheral portion of the light transmissive solid.