Optical system for a light emitting diode with collection, conduction, phosphor directing, and output means

• US 8,152,318 B2
• Filed: 06/11/2009
• Issued: 04/10/2012
• Est. Priority Date: 06/11/2009
• Status: Expired due to Fees

• Current Assignee: Rambus Delaware LLC (Rambus Inc.)
• Original Assignee: Rambus International Ltd (Rambus Inc.)
• Inventors: Richardson, Brian Edward
• Primary Examiner(s): Sember, Thomas
• Application Number:
  US12/456,126
• Publication Number:
  US 20100315802A1
• Time in Patent Office: 1,034 Days
• Field of Search: 362/84, 362/268, 362/293, 362/307, 362/308, 362/310, 362/311.02, 362/328, 362/329, 362/331, 362/332, 362/335, 362/347
• US Class Current: 362/84
• CPC Class Codes: F21K 9/68 Details of reflectors forming part of the light source
• CPC Class Codes: F21V 13/04 the elements being reflectors and refractors for vehicle rear lights F21S43/40
• CPC Class Codes: F21V 13/08 the elements being filters or photoluminescent elements and reflectors
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21V 9/06 for filtering out ultraviolet radiation
• CPC Class Codes: F21V 9/30 Elements containing photoluminescent material distinct from or spaced from the light source shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

An optical system with an LED light source utilizes a base with an inverted conical shape to conduct light to a phosphor layer. The phosphor layer emits light from both upper and lower surfaces. The base and a substantially mirror image cap element facilitate efficient extraction of the phosphor-generated light from the optical system so that the output of the system is omni-directional light suitable for common lighting applications. The system is very efficient in that nearly all the light generated by the LED is transmitted to the phosphor layer, and nearly all the light emitted from the phosphor layer is output from the system.

Claims

1. A lighting assembly with an omnidirectional light output, comprising:

a first light guide frustoconical in shape, the first light guide comprising a base, a light input surface opposite the base, and a first side wall extending between the base and the light input surface;

an LED light source adjacent the light input surface;

a second light guide conical or frustoconical in shape, the second light guide comprising a base, an apex region opposite the base, and a second side wall extending between the base and the apex region, the second light guide arranged base-to-base with the first light guide; and

a phosphor layer between the bases of the light guides, the first light guide guides primary light generated by the light source to the phosphor layer directly and by total internal reflection at the first side wall;

wherein;

the phosphor layer converts at least a portion of the primary light to secondary light of longer wavelengths, and outputs the secondary light into the first light guide and the second light guide; and

the secondary light and an unconverted portion of the secondary light are output from the lighting assembly omnidirectionally through the first and second side surfaces of the light guides directly and after total internal reflection at the side surfaces.

2. The lighting assembly of claim 1, wherein the phosphor layer is larger in area than the light source.

3. The lighting assembly of claim 1, wherein an area of the first light guide near the light source comprises a reflector medium.

4. The lighting assembly of claim 3, wherein at least a portion of the reflector medium is covered by a reflective coating.

5. The lighting assembly of claim 3, wherein the reflector medium comprises oil having a high index of refraction.

6. The lighting assembly of claim 3, wherein the reflector medium comprises a polymer.

7. The lighting assembly of claim 3, wherein the reflector medium and the first light guide are constructed of a single piece of material.

8. The lighting assembly of claim 3, wherein the reflector medium surrounds the light source.

9. The lighting assembly of claim 3, wherein the reflector medium comprises a reflective coating.

10. The lighting assembly of claim 3, wherein the first light guide additionally guides the primary light to the phosphor layer by reflection at the reflector medium.

11. The lighting assembly of claim 1, wherein the second light guide is frustoconical in shape.

12. The lighting assembly of claim 1, additionally comprising a reflective coating on the first light guide near the light input surface.

13. The lighting assembly of claim 1, additionally comprising a reflector medium surrounding the light source.

14. The lighting assembly of claim 13, wherein the reflector medium comprises a reflective coating.

15. The lighting assembly of claim 1, additionally comprising a high refractive index material between the light source and the light input surface.

16. The lighting assembly of claim 15, wherein the high refractive index material is in contact with the light source.

17. The lighting assembly of claim 1, wherein at least one of the first light guide and the second light guide has a conical angle of less than 105 degrees.

18. The lighting assembly of claim 17, wherein the at least one of the first light guide and the second light guide has a conical angle of less than 95 degrees.

19. The lighting assembly of claim 18, wherein the at least one of first light guide and the second light guide has a conical angle of about 87 degrees.

20. The lighting assembly of claim 1, wherein the light guides have respective conical angles configured such that the secondary light that is totally internally reflected exits the light guides after no more than one total internal reflection.