LED illumination device with layered phosphor pattern

• US 7,327,078 B2
• Filed: 03/30/2004
• Issued: 02/05/2008
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: Lumination LLC
• Inventors: Shiang, Joseph John, Becker, Charles Adrian, Srivastava, Alok Mani, Weaver, Stanton Earl, Comanzo, Holly Ann, Setlur, Anant Achyut
• Primary Examiner(s): Patel; Ashok
• Application Number:
  US10/813,338
• Publication Number:
  US 20050227388A1
• Time in Patent Office: 1,407 Days
• Field of Search: None
• US Class Current: 313/499
• CPC Class Codes: C09K 11/665 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: C09K 11/774 Borates
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials

Abstract

A method of applying at least two phosphors to an LED, wherein a first phosphor material having a lower absorption, shorter luminescence decay time, and/or lower thermal quenching than a second phosphor material is positioned closer to the LED than the second phosphor. Such an arrangement provides a light emitting device with improved lumen output and color stability over a range of drive currents.

Claims

1. A light emitting device comprising a semiconductor light emitter and at least two phosphor materials, wherein a first phosphor material is disposed closer to said semiconductor light emitter than a second phosphor material, said first phosphor material having at least one of a shorter decay time and a lower absorption of radiation emitted from said semiconductor light emitter than said second phosphor material.

2. A device according to claim 1, wherein said semiconductor light emitter comprises a light emitting diode or a laser diode.

3. A device according to claim 1, wherein said semiconductor light emitter emits between about 350 and 440 nm.

4. A device according to claim 1, wherein said first phosphor material is disposed in a matrix material and applied to the LED as a layer.

5. A device according to claim 4, wherein said matrix material is selected from silicone, epoxy and mixtures thereof.

6. A device according to claim 1, further comprising one or more additional phosphor materials.

7. A device according to claim 1, wherein said first phosphor material has at least one of a luminescence decay time of less than about 3 ms and a plaque absorption of less than about 60% at a mean particle size of 10 μ

m.

8. A device according to claim 1, wherein said second phosphor material has at least one of a luminescence decay time of greater than about 10 ms and a plaque absorption of greater than about 80% at a mean particle size of 10 μ

m.

9. A device according to claim 1, wherein said first phosphor material comprises phosphors co-activated with Eu²⁺ and Mn²⁺.

10. A device according to claim 1, wherein said first phosphor material comprises (Sr,Ca,Ba,Mg,Zn)₂P₂O₇:

Eu²⁺, Mn²⁺;

Sr₄Al₁₄O₂₅;

Eu²⁺;

or blends thereof.

11. A device according to claim 1, wherein said second phosphor material comprises (Ca,Sr,Ba,Mg)₁₀(PO₄)₆(F,Cl,Br,OH):

Eu²⁺, Mn²⁺.

12. A device according to claim 1, wherein said first phosphor material comprises one or more of (Ba,Sr,Ca)Al₂O₄:

Eu²⁺;

(Ba,Sr,Ca)₂SiO₄;

Eu²⁺;

(Ba,Sr,Ca)₂(Mg,Zn)Si₂O₇;

Eu²⁺;

(Sr,Ca,Ba)(Al,Ga,In)₂S₄;

Eu²⁺;

(Ca,Sr,Ba,Mg)₁₀(PO₄)₆(F,Cl,Br,OH);

Eu²⁺;

(Ca,Sr)₈(Mg,Zn)(SiO₄)₄Cl₂;

Eu²⁺;

(Ba,Sr,Ca)MgAl₁₀O₁₇;

Eu²⁺;

(Sr,Ca)₁₀(PO₄)₆*nB₂O₃;

Eu²⁺;

2SrO*0.84P₂O₅*0.16B₂O₃;

Eu²⁺;

Sr₂Si₃O₈*2SrCl₂;

Eu²⁺;

Ba₃MgSi₂O₈;

Eu²⁺;

Sr₄Al₁₄O₂₅;

Eu²⁺;

BaAl₈O₁₃;

Eu²⁺;

(Y,Gd,Tb,La,Sm,Pr,Lu)₃(Al,Ga)₅O₁₂;

Ce³⁺; and

blends thereof.

13. A device according to claim 1, wherein said second phosphor material comprises one or more of (Ba,Sr,Ca)MgAl₁₀O₁₇:

Eu²⁺, Mn²⁺;

(Sr,Ca,Ba,Mg,Zn)₂P₂O₇;

Eu²⁺, Mn²⁺;

(Ca,Sr,Ba,Mg)₁₀(PO₄)₆(F,Cl,Br,OH);

Eu²⁺,Mn²⁺;

(Ca,Sr)₈(Mg,Zn)(SiO₄) ₄C₁₂;

Eu²⁺,Mn²⁺;

(Ba,Sr,Ca)MgP₂O₇;

Eu²⁺,Mn²⁺;

3.5MgO*0.5MgF₂*GeO₂;

Mn⁴⁺;

(Ca,Sr,Ba,Mg)₁₀(PO₄)₆(F,Cl,Br,OH);

Eu²⁺,Mn²⁺;

(Ca,Sr)₈(Mg,Zn)(SiO₄)₄Cl₁₂;

Eu²⁺,Mn²⁺; and

blends thereof.

14. A device according to claim 1 having a color temperature between about 2,500 k and 10,000 k.

15. A device according to claim 1 having a CRI of at least 50.

16. A light emitting device comprising a light emitting diode or laser emitting diode and at least two phosphor materials, wherein a first phosphor material is positioned such that radiation emitted from said light emitting diode or laser emitting diode strikes said first phosphor material prior to striking said second phosphor material, and further wherein said first phosphor material has at least one of a shorter decay time and a lower absorption of radiation emitted from said light emitting diode or laser emitting diode than said second phosphor material.

17. A light emitting device according to claim 16, wherein said first phosphor material has a lower thermal quenching than said second phosphor material.