Light emitting device including nearly index-matched luminescent glass-phosphor composites

• US 9,420,664 B2
• Filed: 07/06/2015
• Issued: 08/16/2016
• 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:
  US14/792,501
• Publication Number:
  US 20160066389A1
• Time in Patent Office: 407 Days
• 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 light source;

a first non-planar layer spaced apart from the light source by a gap, wherein the first non-planar layer is composed of a light emitting composite material comprising

a glassy material; and

a plurality of phosphor particles suspended within the glassy material, wherein a refractive index of the phosphor particles is approximately equal to a refractive index n₂ of the glassy material; and

a second non-planar layer composed from the glassy material and having

an inner non-planar surface in contact with the first non-planar layer, the inner non-planar surface having an inner radius of curvature r; and

an outer non-planar surface facing away from the first non-planar layer and being a surface through which the light emitting device emits light into a medium adjacent the outer non-planar surface, the medium having a refractive index n₁, the outer non-planar surface having an outer radius of curvature R, that satisfies the condition r/R=n₁/n₂.

2. The light emitting device of claim 1, wherein the plurality of phosphor particles are composed of an inorganic crystalline material selected from the group consisting of:

Y_xGd_yAl_vGa_wO₁₂;

M³⁺, wherein x+y=3 and v+w=5;

SrGa₂S₄;

M²⁺;

SrS;

M²⁺;

X₂Si₅N₈M²⁺; and

XSi₂O₂N₂;

M²⁺, wherein X is selected from the group consisting of Be, Mg, Ca, Sr, and Ba and wherein M is selected from a group consisting of Ce, Eu, Mn, Nd, Pr, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ir, and Pt.

3. The light emitting device of claim 1, wherein the glassy material is an optical glass comprising:

an amount from about 5% to about 35% of SiO₂;

an amount from about 55% to about 88% of PbO;

optionally an amount less than about 10% of B₂O₃;

optionally a combined amount less than about 8% of Na₂O and K₂O; and

optionally a combined amount less than about 15% total of TiO₂, ZrO₂, La₂O₃, ZnO, and BaO.

4. The light emitting device of claim 1, wherein the glassy material is an optical glass comprising:

an amount from about 21% to about 30% of TiO₂;

an amount from about 30% to about 50% of BaO, NaO, BeO, CaO, SrO, CdO, Ga₂O₃, In₂O₃, or Y₂O₃;

an amount from about 18% to about 24% of Al₂O₃; and

an amount from about 1% to about 10% of SiO₂, B₂O₃, PbO, GeO₂, SnO₂, ZrO₂, HfO₂, or ThO₂.

5. The light emitting device of claim 1, wherein the glassy material is a Schott glass.

6. The light emitting device of claim 1, wherein the refractive index of the plurality of phosphor particles is within five percent of the refractive index of the glassy material.

7. The light emitting device of claim 1, wherein the plurality of phosphor particles are composed of Y₃Al₅O₁₂:

Ce³⁺ and the glassy material is a Schott glass.

8. The light emitting device of claim 1, wherein the plurality of phosphor particles have a size ranging from about 100 nm to about 100 μ

m.

9. The light emitting device of claim 1, wherein the plurality of phosphor particles are composed of an inorganic crystalline material having a refractive index of about 1.5 to about 2.8 and the glassy material has a refractive index of about 1.5 to about 2.8.

10. The light emitting device of claim 1, wherein the light source is configured to emit first wavelength ranges from about 350 nm to about 500 nm.

11. The light emitting device of claim 1, wherein the light source is selected from the group consisting of a laser, a diode, and a flashlamp.

12. The light emitting device of claim 1, wherein the light source and the first and second non-planar layers are positioned on a planar reflector.

13. The light emitting device of claim 1, wherein the first and second non-planar layers are integral.

14. The light emitting device of claim 1, wherein the first and second non-planar layers are hemispherical.

15. The light emitting device of claim 1, wherein the first and second non-planar layers are spherical.

16. The light emitting device of claim 1, wherein the gap is an air gap.