Semiconductor White Light Sources

Abstract

A semiconductor white light source includes a blue emitting semiconductor; a dispersant material disposed about the blue emitting semiconductor; an ultraviolet emitting semiconductor; and a wavelength shifting medium with maximum excitation in the ultraviolet spectrum disposed about the dispersant material and the ultraviolet emitting semiconductor such that ultraviolet light output by the ultraviolet emitting semiconductor illuminates the wavelength shifting medium directly and blue light output by the blue emitting semiconductor illuminates the wavelength shifting medium after passage of the blue light through the dispersant material. The dispersant material and the wavelength shifting medium are separate materials. The blue emitting semiconductor and the ultraviolet emitting semiconductor are arranged to emit light into a common illumination field.

1 . A semiconductor white light source comprising:
 a blue emitting semiconductor;   a dispersant material disposed about the blue emitting semiconductor;   an ultraviolet emitting semiconductor; and   a wavelength shifting medium with maximum excitation in the ultraviolet spectrum disposed about the dispersant material and the ultraviolet emitting semiconductor such that ultraviolet light output by the ultraviolet emitting semiconductor illuminates the wavelength shifting medium directly and blue light output by the blue emitting semiconductor illuminates the wavelength shifting medium after passage of the blue light through the dispersant material, wherein:
 the dispersant material and the wavelength shifting medium are separate materials; and 
 the blue emitting semiconductor and the ultraviolet emitting semiconductor are arranged to emit light into a common illumination field. 
   
     
     
         2 . The semiconductor white light source of  claim 1 , wherein the semiconductors lie under a plano-convex optical lens having a cavity in the plano side, the cavity at least partly filled with the wavelength shifting medium and the dispersant material, 
     
     
         3 . The semiconductor white light source of  claim 1 , wherein the optical lens is formed from a hard plastic optical grade material. 
     
     
         4 . The semiconductor white light source of  claim 1 , wherein the semiconductors are comprised of InGaN. 
     
     
         5 . The semiconductor white light source of  claim 4 , wherein the ultraviolet emitting semiconductor has an emission spectral peak between about 365 and 420 nanometers, the blue emitting semiconductor has an emission spectral peak between about 445 and 480 nanometers, and the wavelength shifting medium has an emission spectral peak between about 540 and 580 nanometers. 
     
     
         6 . The semiconductor white light source of  claim 1 , wherein the wavelength shifting medium is a colloid of phosphor grains suspended in a binder material. 
     
     
         7 . The semiconductor white light source of  claim 6 , wherein the wavelength shifting medium includes phosphors characterized as either silicates or thiogallates. 
     
     
         8 . The semiconductor white light source of  claim 1 , wherein the blue emitting semiconductor and the ultraviolet emitting semiconductor are arranged closely spaced and side-by-side on a substrate whereby each of their primary emission surface is substantially parallel to a mounting surface of the substrate, and their emission fields form a substantial overlap. 
     
     
         9 . The semiconductor white light source of  claim 6 , wherein the blue emitting semiconductor and the ultraviolet emitting semiconductor are arranged closely spaced and side-by-side on a substrate whereby each of their primary emission surface is substantially parallel to a mounting surface of the substrate, and their emission fields form a substantial overlap in the far-field of the lens. 
     
     
         10 . The semiconductor white light source of  claim 2 , further comprising: a mounting substrate arranged to form an enclosed cavity when the mounting substrate and the optical lens are mated together. 
     
     
         11 . The semiconductor white light source of  claim 2 , wherein the dispersant material and the wavelength shifting material together substantially fill the cavity. 
     
     
         12 . The semiconductor white light source of  claim 11 , wherein the dispersant material and the wavelength shifting material are respectively comprised of a colloid of dispersant grains and a colloid of phosphor grains suspended in a binder material. 
     
     
         13 . The semiconductor white light source of  claim 1 , further comprising a current source coupled to the blue emitting semiconductor. 
     
     
         14 . The semiconductor white light source of  claim 13 , wherein the current source is variable. 
     
     
         15 . The semiconductor white light source of  claim 5 , further comprising a current source coupled to the blue emitting semiconductor. 
     
     
         16 . The semiconductor white light source of  claim 15 , wherein the current source is variable. 
     
     
         17 . The semiconductor white light source of  claim 8 , further comprising a current source coupled to the blue emitting semiconductor, 
     
     
         18 . The semiconductor white light source of  claim 17 , wherein the current source is variable.