Led with ceramic green phosphor and protected red phosphor layer

Abstract

A ceramic green wavelength conversion element (120) is coated with a red wavelength conversion material (330) and placed above a blue light emitting element (110) such that the ceramic element (120) is attached to the light emitting element (110), thereby providing an efficient thermal coupling from the red and green converters (330, 120) to the light emitting element (110) and its associated heat sink. To protect the red converter coating (330) from the effects of subsequent processes, a sacrificial clear coating (340) is created above the red converter element (330). This clear coating (340) may be provided as a discrete layer of clear material, or it may be produced by allowing the red converters to settle to the bottom of its suspension material, thereby forming a converter-free upper layer that can be subjected to the subsequent fabrication processes.

1 . (canceled) 
     
     
         2 . A wavelength conversion structure comprising:
 a ceramic wavelength conversion element comprising a first wavelength conversion material configured to absorb light of a first wavelength and in response emit light of a second and longer wavelength;   a wavelength conversion layer disposed on a surface of the ceramic wavelength conversion element and comprising particles of a second wavelength conversion material dispersed in a binder material, the second wavelength conversion material configured to absorb light of the first wavelength and in response emit light of a third and longer wavelength different from the second wavelength; and   a transparent coating disposed on a surface of the wavelength conversion layer opposite from the ceramic wavelength conversion element, the transparent coating substantially transparent to light of the first, second, and third wavelengths.   
     
     
         3 . The wavelength conversion structure of  claim 2 , wherein the transparent coating comprises a roughened surface opposite from the wavelength conversion layer. 
     
     
         4 . The wavelength conversion structure of  claim 2 , wherein the transparent coating comprises a silicone. 
     
     
         5 . The wavelength conversion structure of  claim 2 , wherein the binder is or comprises a silicone. 
     
     
         6 . The wavelength conversion structure of  claim 2 , wherein the transparent coating is formed from the same material as the binder material. 
     
     
         7 . The wavelength conversion structure of  claim 2 , wherein the first wavelength is in the blue region of the visible spectrum, the second wavelength is in the green region of the visible spectrum, and the third wavelength is in the red region of the visible spectrum. 
     
     
         8 . The wavelength conversion structure of  claim 2 , comprising an adhesive layer disposed on a surface of the ceramic wavelength conversion element opposite from the wavelength conversion layer. 
     
     
         9 . The wavelength conversion structure of  claim 2 , wherein the wavelength conversion layer has a thickness between 5 and 50 microns and the transparent coating has a thickness between 2 and 100 microns. 
     
     
         10 . The wavelength conversion structure of  claim 2 , wherein:
 the transparent coating comprises a roughened surface opposite from the wavelength conversion layer; and   the first wavelength is in the blue region of the visible spectrum, the second wavelength is in the green region of the visible spectrum, and the third wavelength is in the red region of the visible spectrum.   
     
     
         11 . The wavelength conversion structure of  claim 10 , wherein the transparent coating comprises a silicone. 
     
     
         12 . The wavelength conversion structure of  claim 11 , wherein the wavelength conversion layer has a thickness between 5 and 50 microns and the transparent coating has a thickness between 2 and 100 microns. 
     
     
         13 . The wavelength conversion structure of  claim 12 , comprising an adhesive layer disposed on a surface of the ceramic wavelength conversion element opposite from the wavelength conversion layer. 
     
     
         14 . A light emitting device comprising:
 a light emitting element configured to emit light having a first wavelength;   a wavelength conversion structure comprising:
 a ceramic wavelength conversion element comprising a first wavelength conversion material configured to absorb light of the first wavelength and in response emit light of a second and longer wavelength; 
 a wavelength conversion layer disposed on a surface of the ceramic wavelength conversion element and comprising particles of a second wavelength conversion material dispersed in a binder material, the second wavelength conversion material configured to absorb light of the first wavelength and in response emit light of a third and longer wavelength different from the second wavelength; and 
 a transparent coating disposed on a surface of the wavelength conversion layer opposite from the ceramic wavelength conversion element, the transparent coating substantially transparent to light of the first, second, and third wavelengths; and 
   an adhesive layer bonding the wavelength conversion structure to the light emitting element.   
     
     
         15 . The light emitting device of  claim 14 , wherein the light emitting element is or comprises a light emitting diode. 
     
     
         16 . The light emitting device of  claim 14 , comprising a reflective material disposed on side surfaces of each of the light emitting element, the ceramic wavelength conversion element, the wavelength conversion layer, and the transparent coating. 
     
     
         17 . The light emitting device of  claim 14 , wherein the first wavelength is in the blue region of the visible spectrum, the second wavelength is in the green region of the visible spectrum, and the third wavelength is in the red region of the visible spectrum. 
     
     
         18 . The light emitting device of  claim 14 , wherein the transparent coating comprises a roughened surface opposite from the wavelength conversion layer. 
     
     
         19 . The light emitting device of  claim 14 , wherein:
 the light emitting element is or comprises a light emitting diode;   the first wavelength is in the blue region of the visible spectrum, the second wavelength is in the green region of the visible spectrum, and the third wavelength is in the red region of the visible spectrum; and   the transparent coating comprises a roughened surface opposite from the wavelength conversion layer.   
     
     
         20 . The light emitting device of  claim 19 , comprising a reflective material disposed on side surfaces of each of the light emitting element, the ceramic wavelength conversion element, the wavelength conversion layer, and the transparent coating. 
     
     
         21 . The light emitting device of  claim 20 , wherein the transparent coating comprises a silicone.