Illumination system comprising a radiation source and a fluorescent material

• US 7,573,189 B2
• Filed: 03/05/2004
• Issued: 08/11/2009
• Est. Priority Date: 03/17/2003
• 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, Schmidt, Peter, Busselt, Wolfgang, Mayr, Walter
• Primary Examiner(s): Roy; Sikha
• Assistant Examiner(s): Green; Tracie
• Application Number:
  US10/549,231
• Publication Number:
  US 20060158097A1
• Time in Patent Office: 1,985 Days
• Field of Search: None
• US Class Current: 313/503
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 33/502 Wavelength conversion materials

Abstract

The invention relates to an illumination system comprising a radiation source and a fluorescent material comprising at least one phosphor capable of absorbing a portion of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said at least one phosphor is a green-emitting cerium-activated lutetium-aluminum-garnet of general formula (Lu1-x-y-a-bYxGdy)3(Al1-zGaz)5O12:CeaPrb wherein 0<x<1, 0<y<1, 0<z£0.1, 0<a£0.2 and 0<b£0.1. The invention also relates to with a green-emitting cerium-activated lutetium-aluminum-garnet of general formula (Lu1-x-y-a-bYxGdy)3(Al1-zGaz)5O12:CeaPrb wherein 0<x<1, 0<y<1, 0<z£0.1, 0<a£0.2 and 0<b£0.1.

Claims

1. Illumination system comprising a radiation source and a fluorescent material comprising at least one phosphor capable of absorbing a portion of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light;

wherein said at least one phosphor is a garnet of general formula

(Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂;

Ce_aPr_b, wherein 0<

x<

1, 0<

y<

1, 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1; and

wherein values of x and y are selected such that 1-x-y-a-b>

0.

2. Illumination system according to claim 1, wherein the radiation source is selected from the radiation sources having an emission with a peak emission wavelength in a range of 400 to 480 nm.

3. Illumination system according to claim 1, wherein the radiation source is a light-emitting diode.

4. Illumination system according to claim 1, wherein the fluorescent material is a phosphor blend comprising a garnet of general formula

(Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂:

Ce_aPr_b wherein 0<

x<

1, 0<

y<

1 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1 and at least one second phosphor.

5. Illumination system according to claim 1, wherein the radiation source is a blue-emitting diode and the fluorescent material is a phosphor blend comprising a garnet of general formula

(Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂:

Ce_aPr_b, wherein 0<

x<

1, 0<

y<

1, 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1 and a red phosphor.

6. Illumination system according to claim 5, wherein the fluorescent material is a phosphor blend comprising a garnet of general formula (Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂:

Ce_aPr_b wherein 0<

x<

1, 0<

y<

1, 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1 and a red phosphor selected from the group of Eu(II)-activated phosphors.

7. Illumination system according to claim 5, wherein the fluorescent material is a phosphor blend comprising a garnet of general formula (Lu_1-x-y-a-bY_xGd_y)₃(Al_zGa_z)₅O₁₂:

Ce_aPr_b wherein 0<

x<

1, 0<

y<

1, 0<

z≦

0.1, 0<

a≦

0.2 and 0<

b≦

0.1 and a red phosphor selected from the group

(Ca_1-xSr_x)S;

Eu, wherein 0.1≦

x≦

1 and (Sr_1-x-yBa_xCa_y)_2-zSi_5-aAl_aN_8-aO_a;

Eu_z wherein 0.1≦

a<

5, 0<

x≦

1, 0≦

y≦

1 and 0<

z≦

1.

10. The illumination system of claim 1, wherein said at least one phosphor comprises one of (Lu_0.99Ce_0.01)₃Al₅O₁₂, (Lu_0.989Ce_0.01Pr_0.001)₃Al₅O₁, (Lu_0.495Y_0.495Ce_0.01)₃Al₅O₁₂, and (Lu_0.75Gd_0.24Ce_0.01)₃Al₅O₁₂.

8. Phosphor capable of absorbing a portion of the light emitted by a radiation source and emitting light of a wavelength different from that of the absorbed light;

wherein said phosphor is a garnet of general formula

(Lu_1-x-y-a-bY_xGd_y)₃(Al_1-zGa_z)₅O₁₂;

Ce_aPr_b wherein 0<

x<

1, 0<

y<

1, 0<

z≦

1, 0<

a≦

0.2 and 0<

b≦

1; and

wherein values of x and y are selected such that 1-x-y-a-b<

0.

9. Phosphor according to claim 8, wherein the phosphor has a coating selected from the group of fluorides and orthophosphates of the elements aluminum, scandium, yttrium, lanthanum, gadolinium and lutetium, the oxides of aluminum, yttrium and lanthanum and the nitride of aluminum.

11. The phosphor of claim 8, wherein said phosphor comprises one of (Lu_0.99Ce_0.01)₃Al₅O₁₂, (Lu_0.989Ce_0.01Pr_0.001)₃Al₅O₁, (Lu_0.495Y_0.495Ce_0.01)₃Al₅O₁₂, and (Lu_0.75Gd_0.24Ce_0.01)₃Al₅O₁₂.