Led assembly

Abstract

A light emission diode (LED) assembly, comprising a LED die ( 10 ), a phosphor layer ( 12 ), and a filter layer ( 14 ), wherein said filter layer ( 14 ) is developed in such a manner that light rays with a wavelength of about 400 nm to 500 nm, preferably of about 420 nm to 490 nm, emitted from the LED die ( 10 ) are at least partially reflected depending on their emission angle to the normal on the filter layer ( 14 ). With the inventive LED assembly it is possible to provide a LED assembly which solves the yellow ring problem without a reduction of the efficiency of the LED assembly.

1 . A device comprising:
 a light emitting diode that emits first light;   a color converter that is stimulated by the first light to emit second light; and   a filter that reflects 10% to 50% of the first light emitted at angles between 0° and 40° and fully transmits first light emitted at larger angles.   
     
     
         2 . The device of  claim 1  wherein the first light comprises light with a wavelength between 400 nm and 500 nm. 
     
     
         3 . The device of  claim 1  wherein the color converter comprises a phosphor. 
     
     
         4 . The device of  claim 1  wherein the filter comprises a dielectric structure comprising alternating low refractive index and high refractive index materials. 
     
     
         5 . The device of  claim 4  wherein the low refractive index materials have a refractive index between 1.2 and 1.8 and the high refractive index materials have a refractive index between 1.6 and 3. 
     
     
         6 . The device of  claim 4  wherein the low index material comprises Nb 2 O 5  and the high refractive index material comprises SiO 2 . 
     
     
         7 . The device of  claim 1  wherein the rest of the first light emitted at angles between 0° and 40° is transmitted by the filter without reflection. 
     
     
         8 . A device comprising:
 a light emitting diode that emits first light;   a color converter that is stimulated by the first light to emit second light; and   a filter that partially reflects the first light emitted at angles between 0° and 30° and fully transmits the first light emitted at angles between 30° and 90°.   
     
     
         9 . The device of  claim 8  wherein the first light is blue and the second light is yellow. 
     
     
         10 . The device of  claim 8  wherein the filter is disposed between the light emitting diode and the color converter. 
     
     
         11 . The device of  claim 8  wherein the color converter is disposed between the light emitting diode and the filter. 
     
     
         12 . The device of  claim 8  wherein the color converter is a first phosphor layer, the device further comprising a second phosphor layer, wherein the filter is disposed between the first phosphor layer and the second phosphor layer. 
     
     
         13 . The device of  claim 8  wherein the color converter comprises a luminescent ceramic. 
     
     
         14 . The device of  claim 8  wherein the color converter comprises a phosphor embedded in a transparent matrix material. 
     
     
         15 . A device comprising:
 a light emitting diode that emits blue light;   a phosphor layer disposed in a path of the blue light, wherein the phosphor layer is stimulated by the blue light to emit yellow light; and   a filter that reflects a portion of the blue light such that the blue light and the yellow light have the same ratio over emission angles from 0° to 90°.   
     
     
         16 . The device of  claim 15  wherein the filter reflects 10% to 50% of the blue light. 
     
     
         17 . The device of  claim 15  wherein blue light at an emission angle near normal is reflected by the filter more than blue light at an emission angle far from normal. 
     
     
         18 . The device of  claim 15  wherein the filter comprises alternating low refractive index and high refractive index materials. 
     
     
         19 . The device of  claim 18  wherein the filter comprises nine layers of low refractive index material and nine layers of high refractive index material.