Light emitting device having a specific dimension of phosphor layer

• US 9,078,332 B2
• Filed: 07/28/2014
• Issued: 07/07/2015
• Est. Priority Date: 07/19/2007
• Status: Active Grant

• Current Assignee: Quarkstar LLC
• Original Assignee: Quarkstar LLC
• Inventors: Allen, Steven C., Steckl, Andrew J.
• Primary Examiner(s): Guharay, Karabi
• Application Number:
  US14/444,829
• Publication Number:
  US 20140333198A1
• Time in Patent Office: 344 Days
• Field of Search: 313/501, 313/512, 313/502, 257/98
• US Class Current: 1/1
• CPC Class Codes: C03C 2204/00 Glasses, glazes or enamels with special properties
• CPC Class Codes: C03C 3/0745 containing more than 50% lead oxide, by weight
• CPC Class Codes: C03C 4/12 for luminescent glass; for fluorescent glass
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/08 containing inorganic luminescent materials
• CPC Class Codes: F21K 9/66 Details of globes or covers 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 3/061 the material being glass
• CPC Class Codes: F21V 3/08 the material comprising photoluminescent substances
• CPC Class Codes: F21V 5/00 Refractors for light sources characterised by cooling arrangements F21V29/504
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21V 7/05 plane
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F21Y 2115/30 Semiconductor lasers
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• 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: H05B 33/02 Details
• CPC Class Codes: H05B 33/12 Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: H05B 33/145 Arrangements of the electroluminescent material
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers

Abstract

A light emitting device includes a light emitting diode (LED); a transparent optic having a refractive index n_optic; and a phosphor layer spaced apart from the LED and positioned between the LED and the transparent optic. The phosphor layer has an effective refractive index n_phosphor, where a gap between the LED and the phosphor layer has a refractive index n_gap that is less than n_phosphor. The transparent optic has an inner convex surface in contact with the phosphor layer. The inner convex surface has an inner radius of curvature r; and an outer convex surface facing away from the phosphor layer and being a surface through which the light emitting device emits light into a medium adjacent the outer convex surface. The medium has a refractive index n_medium. The outer convex surface has an outer radius of curvature R, such that r/R is equal to n_medium/n_optic.

Claims

1. A light emitting device, comprising:

a base;

a light emitting diode supported by the base;

a transparent optic having a refractive index n_optic; and

a phosphor layer spaced apart from the light emitting diode and positioned between the light emitting diode and the transparent optic, the phosphor layer having an effective refractive index n_phosphor, wherein a gap between the light emitting diode and the phosphor layer has a refractive index n_gap that is less than n_phosphor,

wherein the transparent optic has

an inner convex surface in contact with the phosphor layer, the inner convex surface having an inner radius of curvature r, and

an outer convex surface facing away from the phosphor layer and being a surface through which the light emitting device emits light into a medium adjacent the outer convex surface, the medium having a refractive index n_medium, the outer convex surface having an outer radius of curvature R, such that r/R is equal to n_medium/n_optic.

2. The light emitting device of claim 1, wherein the phosphor layer is a non-planar layer.

3. The light emitting device of claim 1, wherein the phosphor layer has the radius of curvature r.

4. The light emitting device of claim 1, wherein the phosphor layer comprises a concave surface facing the light emitting diode.

5. The light emitting device of claim 1, wherein the phosphor layer has a hemispherical, ellipsoidal, or spherical shape.

6. The light emitting device of claim 1, wherein the phosphor layer comprises a composite phosphor material.

7. The light emitting device of claim 6, wherein the composite phosphor material comprises an inorganic crystalline material suspended in a glassy material.

8. The light emitting device of claim 1, wherein the phosphor layer further comprises a polymer, a silicone, or a glass.

9. The light emitting device of claim 1, wherein the light emitting diode and the phosphor layer are selected so that the light emitting device has a broadband white emission spectrum.

10. The light emitting device of claim 1, wherein the outer convex surface of the transparent optic has a hemispherical, ellipsoidal, or spherical shape.

11. The light emitting device of claim 1, wherein n_optic is equal to or larger than n_phosphor.

12. The light emitting device of claim 1, wherein n_optic is in a range from about 1.3 to about 2.2.

13. The light emitting device of claim 1, further comprising a reflector extending between the light emitting diode and the phosphor layer.

14. The light emitting device of claim 13, wherein the reflector extends adjacent the phosphor layer and the transparent optic.

15. The light emitting device of claim 13, wherein the reflector is a planar reflector.

16. The light emitting device of claim 13, wherein the gap is an air gap.