Ceramic wavelength converter and LED light source containing same
View Patent ↗There is herein described an LED light source comprising an LED and a ceramic wavelength converter positioned to receive at least a portion of the light emitted by said LED, said ceramic wavelength converter converting at least a portion of the light emitted by said LED into light of a different wavelength, said ceramic wavelength converter comprising a chlorosilicate phosphor and having a density at least about 90% of theoretical density. The chlorosilicate phosphor is preferably a green-emitting Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu 2+ phosphor.
1. An LED light source, comprising: an LED and a ceramic wavelength converter positioned to receive at least a portion of the light emitted by said LED, said ceramic wavelength converter converting at least a portion of the light emitted by said LED into light of a different wavelength, said ceramic wavelength converter comprising a chlorosilicate phosphor and having a density at least about 90% of theoretical density.
2. The LED light source of claim 1 wherein said chlorosilicate phosphor is a green-emitting phosphor.
3. The LED light source of claim 1 said ceramic wavelength converter includes a second phosphor.
4. The LED light source of claim 3 wherein said second phosphor is (Sr,Ca) 2 Si 5 N 8 :Eu.
5. The LED light source of claim 1 wherein said chlorosilicate phosphor is Ca 8 Mg(SiO 4 ) 4 Cl 2 , having one or more activators selected from the group consisting of Eu 2+ , Mn 2+ , Dy 3+ , or Ce 3+ .
6. The LED light source of claim 2 wherein said green-emitting chlorosilicate phosphor is Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu 2+ .
7. A ceramic wavelength converter comprised of a chlorosilicate phosphor Ca 8 Mg(SiO 4 ) 4 Cl 2 , having one or more activators selected from the group consisting of Eu 2+ , Mn 2+ , Dy 3+ , or Ce 3+ and having a density at least about 90% of theoretical density.
8. The ceramic wavelength converter of claim 7 wherein the converter is comprised of Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu 2+ .
9. A method of making a ceramic wavelength converter for use with a light emitting diode, comprising the steps of:
obtaining a chlorosilicate phosphor Ca 8 Mg(SiO 4 ) 4 Cl 2 , having one or more activators selected from the group consisting of Eu 2+ , Mn 2+ , Dy 3+ , or Ce 3+ ; and
hot-pressing said phosphor at a temperature of 900-1100° C. in a slightly reducing atmosphere to achieve a density at least about 90% of theoretical density.
10. The method of claim 9 wherein said phosphor has a particle size of 5-15 microns.
11. The method of claim 9 wherein said phosphor is hot pressed at a pressure of 2-2.5 ksi in an atmosphere of N 2 containing 4% H 2 .
12. The method of claim 9 wherein a second phosphor is combined with said chlorosilicate phosphor to form a phosphor mixture prior to hot pressing, said second phosphor having a formula (Sr,Ca) 2 Si 5 N 8 :Eu.
13. The method of claim 12 wherein said chlorosilicate phosphor comprises 80 volume % of said mixture and said second phosphor comprises 20 volume % of said mixture.
14. The method of claim 12 wherein the chlorosilicate phosphor has a formula Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu 2+ .