Light-emitting device with coated phosphor

• US 20020105266A1
• Filed: 10/16/2001
• Published: 08/08/2002
• Est. Priority Date: 10/17/2000
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Juestel, Thomas, Ronda, Cornelis Reinder, Schmidt, Peter, Mayr, Walter, Weiler, Volker Ulrich
• Granted Patent: US 7,202,598 B2
• Time in Patent Office: Days
• US Class Current: 313/512
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 33/501 characterised by the materials, e.g. binder

Abstract

The invention describes a light-emitting device (1) which comprises a light-emitting diode and a phosphor layer. To prolong the useful life of the light-emitting device (1), a phosphor (4) in the phosphor layer (2) has a water-resistant coating. FIG. 1

Claims

1. A light-emitting device (1) provided with at least one light-emitting diode (3) and a phosphor layer (2) which comprises at least a phosphor (4) with a coating.

2. A light-emitting device as claimed in claim 1, characterized in that the coating is chosen from the group comprising organic materials, inorganic materials, and glass materials.

3. A light-emitting device as claimed in claim 2, characterized in that the organic material is chosen from the group comprising latex and polyorganosiloxane.

4. A light-emitting device as claimed in claim 2, characterized in that the glass material is chosen from the group comprising borosilicates, phosphosilicates, and alkali silicates.

5. A light-emitting device as claimed in claim 2, characterized in that the inorganic material is chosen from the group comprising oxides, borates, phosphates, and combinations of these materials.

6. A light-emitting device as claimed in claim 5, characterized in that the phosphate is an orthophosphate MPO₄, in which M is chosen from the group comprising Al, La, Sc, Y, and Lu, or a polyphosphate with a chain length n of between 10¹ and 10⁶ and having a composition (M_0.5PO₃)_n, in which M is chosen from the group of Ca, Sr, and Ba.

7. A light-emitting device as claimed in claim 1, characterized in that the phosphor (4) is chosen from the group comprising oxidic phosphors , sulfidic phosphors, aluminate phosphors, borate phosphors, vanadate phosphors, and silicate phosphors.

8. A light-emitting device as claimed in claim 7, characterized in that the aluminate phosphor is chosen from the group comprising Y₃Al₅O₁₂:

Ce, (Y,Gd)₃(Al,Ga)₅O₁₂;

Ce and BaMgAl₁₀O₁₇;

Eu,Mn.

9. A light-emitting device as claimed in claim 7, characterized in that the sulfidic phosphor is chosen from the group comprising SrS:

Eu, SrGa₂S₄;

Eu, (Sr,Ca,Ba)(Al,Ga)₂S₄;

Eu, SrY₂S₄;

Eu, (Ca,Sr)S;

Eu, (Mg,Ca)S;

Eu, SrS;

Ce, CaS;

Ce, CaLa₂S₄;

Ce and CaS;

Ce,Eu.

10. A light-emitting device as claimed in any one of the preceding claims, characterized in that the phosphor layer (2) comprises SrS:

Eu with a coating of SiO₂ and a silicate.