Illumination assembly including wavelength converting material having spatially varying density

Abstract

Illumination assemblies, components, and related methods are described. An illumination assembly can include at least one solid state light-emitting device, an emission surface through which light is emitted, and a wavelength converting material that wavelength converts at least some light emitted by the solid state light-emitting device. The wavelength converting material can have a first density per unit area of the emission surface at a first location and a second density per unit area of the emission surface at a second location, wherein the second density is substantially different from the first density, and wherein the density per unit area is defined with a 1×1 cm 2 averaging area. Another illumination assembly can include a light guide configured to receive light emitted by a solid state light-emitting device. The light guide can have a length along which received light propagates and an emission surface substantially parallel to the length of the light guide and through which light is emitted. A wavelength converting material can have a density per unit area of the emission surface that substantially increases along the length of the light guide.

1 . An illumination assembly comprising:
 at least one solid state light-emitting device;   an emission surface through which light is emitted; and   a wavelength converting material that wavelength converts at least some light emitted by the solid state light-emitting device, the wavelength converting material having a first density per unit area of the emission surface at a first location and a second density per unit area of the emission surface at a second location, wherein the second density is substantially different from the first density, and wherein the density per unit area is defined with a 1×1 cm 2  averaging area.   
     
     
         2 . The illumination assembly of  claim 1 , wherein the second density is substantially different from the first density at least partially due to a differing microscopic density of wavelength converting material at the first location and the second location. 
     
     
         3 . The illumination assembly of  claim 1 , wherein the second density is substantially different from the first density at least partially due to a differing thickness of the wavelength converting material at the first location and the second location. 
     
     
         4 . The illumination assembly of  claim 1 , further comprising a plurality of wavelength converting material regions that include the wavelength converting material, and wherein the second density is substantially different from the first density at least partially due to a differing spatial arrangement of the plurality of wavelength converting material regions at the first location and the second location. 
     
     
         5 . The illumination assembly of  claim 4 , wherein the plurality of wavelength converting material regions have substantially similar shapes. 
     
     
         6 . The illumination assembly of  claim 1 , further comprising a plurality of wavelength converting material regions that include the wavelength converting material, and wherein the second density is substantially different from the first density at least partially due to a differing size of the plurality of wavelength converting material regions at the first location and the second location. 
     
     
         7 . The illumination assembly of  claim 1 , wherein the second location is further away from the solid state light-emitting device than the first location and the second density is substantially greater than the first density. 
     
     
         8 . The illumination assembly of  claim 1 , wherein the first and second densities are such that wavelength converted light intensity from the first location is at least 90% the wavelength converted light intensity from the second location and no greater than 110% the wavelength converted light intensity from the second location. 
     
     
         9 . The illumination assembly of  claim 1 , wherein the second density is greater than or equal to 2 times the first density. 
     
     
         10 . The illumination assembly of  claim 1 , wherein the wavelength converting material comprises a phosphor. 
     
     
         11 . The illumination assembly of  claim 1 , wherein the wavelength converting material has a density that increases further away from the solid state light-emitting device. 
     
     
         12 . The illumination assembly of  claim 1 , wherein the illumination assembly further comprises:
 a light guide configured to receive light emitted by the solid state light-emitting device, the light guide having a length along which received light propagates, and   wherein the wavelength converting material has a varying density per unit area of the emission surface along the length of the light guide.   
     
     
         13 . The illumination assembly of  claim 12 , wherein the density of the wavelength converting material per unit area of the emission surface along the length of the light guide varies monotonically with distance along the length of the light guide. 
     
     
         14 . The illumination assembly of  claim 12 , wherein the light guide includes an edge configured to receive the light emitted by the solid state light-emitting device 
     
     
         15 . The illumination assembly of  claim 12 , wherein the wavelength converting material is at least partially disposed within the light guide. 
     
     
         16 . The illumination assembly of  claim 12 , wherein the wavelength converting material is at least partially disposed over a light emission surface of the light guide. 
     
     
         17 . The illumination assembly of  claim 12 , wherein the wavelength converting material is at least partially disposed in contact with the light emission surface of the light guide. 
     
     
         18 . The illumination assembly of  claim 12 , wherein the light guide includes a backside surface opposing a light emission surface of the light guide, and wherein the wavelength converting material is at least partially disposed under the backside surface. 
     
     
         19 . The illumination assembly of  claim 18 , wherein the wavelength converting material is at least partially disposed in contact with the backside surface of the light guide. 
     
     
         20 . The illumination assembly of  claim 12 , wherein the wavelength converting material has a lower density in locations illuminated with a higher intensity of light from the solid state light-emitting device than in locations illuminated with a lower intensity of light from the solid state light-emitting device. 
     
     
         21 . The illumination assembly of  claim 1 , wherein the wavelength converting material comprises a phosphor. 
     
     
         22 . The illumination assembly of  claim 1 , wherein the solid state light-emitting device includes a light emission surface, and wherein the wavelength converting material is disposed over the light emission surface of the solid state light-emitting device. 
     
     
         23 . The illumination assembly of  claim 22 , wherein the at least one solid state light-emitting device includes a plurality of solid state light-emitting devices located on a first plane, and wherein the first and second locations are located at different locations of a second plane parallel to the first plane. 
     
     
         24 . The illumination assembly of  claim 23 , wherein the wavelength converting material has a lower density in locations illuminated with a higher intensity of light from the plurality of solid state light-emitting devices than in locations illuminated with a lower intensity of light from the plurality of solid state light-emitting device. 
     
     
         25 . An illumination assembly comprising:
 a solid state light-emitting device;   a light guide configured to receive light emitted by the solid state light-emitting device, the light guide having a length along which received light propagates and an emission surface substantially parallel to the length of the light guide and through which light is emitted; and   a wavelength converting material having a density per unit area of the emission surface that substantially increases along the length of the light guide.   
     
     
         26 . A display comprising:
 at least one solid state light-emitting device;   an emission surface through which light is emitted;   a wavelength converting material that wavelength converts at least some light emitted by the solid state light-emitting device, the wavelength converting material having a first density per unit area of the emission surface at a first location and a second density per unit area of the emission surface at a second location, wherein the second density is substantially different from the first density, and wherein the density per unit area is defined with a 1×1 cm 2  averaging area; and   a liquid crystal layer arranged to receive at least some wavelength converted light emitted by the wavelength converting material.   
     
     
         27 . A display comprising:
 at least one solid state light-emitting device;   a first wavelength converting material region that wavelength converts at least some light emitted by the solid state light-emitting device to a first wavelength spectrum;   a second wavelength converting material region that wavelength converts at least some light emitted by the solid state light-emitting device to a second wavelength spectrum different from the first wavelength spectrum; and   a liquid crystal layer comprising
 a first pixel light valve arranged to receive at least some wavelength converted light emitted by the first wavelength converting material, and 
 a second pixel light valve arranged to receive at least some wavelength converted light emitted by the second wavelength converting material. 
   
     
     
         28 . A method of making an illumination assembly comprising:
 providing at least one solid state light-emitting device; and   providing a wavelength converting material that wavelength converts at least some light emitted by the solid state light-emitting device, the wavelength converting material having a first density per unit area of an emission surface at a first location and a second density per unit area of the emission surface at a second location, wherein the second density is substantially different from the first density, and wherein the density per unit area is defined with a 1×1 cm 2  averaging area.