White light apparatus with enhanced color contrast

Abstract

A lighting apparatus for emitting white light including a semiconductor light source emitting radiation with a peak emission between from about 250 nm to about 500 nm and a first phosphor having a peak emission between about 550 and 615 nm, wherein an overall emission spectrum of the lighting apparatus has a depression between about 550 and 615 nm, whereby the red-green color contrast is increased versus a reference illuminant.

1 . A lighting apparatus for emitting white light having enhanced red-green color: contrast and comprising: 
 a light source emitting radiation having a peak emission in the range of from about 250 to 500 nm;    a phosphor material radiationally coupled to said light source comprising a first phosphor having a peak emission between about 550 to 615 nm; and    a filter that prevents a portion of radiation emitted by the phosphor material from being emitted by the apparatus while substantially permitting the emission of radiation from the lighting apparatus in emission wavelengths other than between 550 and 615 nm.    
   
   
       2 . The lighting apparatus of  claim 1 , wherein said filter functions such that an overall emission spectrum of the lighting apparatus has a depression between about 550 and 615 nm, said depression extending to between about 5% and 25% of the highest intensity of the emission spectrum of the lighting apparatus in the region from 400 to 700 nm.  
   
   
       3 . The lighting apparatus of  claim 2 , wherein the depression extends to between about 10% and 20% of the highest intensity of the emission spectrum of the lighting apparatus in the region from 400 to 700 nm.  
   
   
       4 . The lighting apparatus of  claim 1 , wherein said filter is a neodymium glass filter that filters out at least a portion of the radiation emitted by said first phosphor.  
   
   
       5 . The lighting apparatus of  claim 1 , wherein said first phosphor comprises at least one of a garnet phosphor doped with Ce 3+  and a silicate phosphor doped with Eu 2+ .  
   
   
       6 . The lighting apparatus of  claim 1 , wherein said lighting apparatus has a general (R a ) CRI of at least 80.  
   
   
       7 . The lighting apparatus of  claim 1 , wherein said phosphor material further comprises one or more additional phosphors.  
   
   
       8 . The lighting apparatus of  claim 1 , wherein the light source is a semiconductor source.  
   
   
       9 . The lighting apparatus of  claim 7 , wherein said phosphor material further comprises a phosphor having a peak emission the range of from about 450 to 550 nm.  
   
   
       10 . The lighting apparatus of  claim 1 , wherein said light source has a peak emission at a wavelength less than 450 nm.  
   
   
       11 . The lighting apparatus of  claim 7 , wherein said phosphor material further comprises a red phosphor having a peak emission in the range of from about 615 nm to 670 nm.  
   
   
       12 . The lighting apparatus of  claim 11 , wherein said red phosphor comprises at least one of 3.5MgO*0.5MgF 2 *GeO 2 :Mn 4+ , Ca 1−2e−f Ce e (Li, Na) e Eu f AlSiN 3 , where 0≦e≦0.2, 0≦f≦0.2, e+f>0; or Ca 1−g−h−i Ce g (Li, Na) h Eu i Al 1+g−h Si 1−g+h N 3  where 0≦g≦0.2, 0<h≦0.4, 0≦i≦0.2, g+i>0; CaAlSiN 3 :Eu 2+  and A 2 [MF 6 ]:Mn 4+  where A=Li, Na, K, Rb or Cs and M=Ge, Si, Sn, Ti or Zr.  
   
   
       13 . The lighting apparatus of  claim 8 , wherein said semiconductor light source comprises a nitride compound semiconductor represented by the formula In i Ga j Al k N, where 0≦i; 0≦j, 0≦k, and i+j+k=1.  
   
   
       14 . The lighting apparatus of  claim 1 , wherein the phosphor material is at least one of coated on the surface of the light source, and dispersed in an encapsulant surrounding the light source and the phosphor material.  
   
   
       15 . The lighting apparatus of  claim 1 , further comprising a reflector.  
   
   
       16 . The lighting apparatus of  claim 1 , wherein said filter comprises neodymium.  
   
   
       17 . The lighting apparatus of  claim 16 , wherein said filter is a neodymium glass.  
   
   
       18 . The lighting apparatus of  claim 1 , wherein said filter is part of a light fixture enclosing the apparatus.  
   
   
       19 . The lighting apparatus of  claim 1 , wherein said filter is in the form of a continuous layer or in powder form.  
   
   
       20 . The lighting apparatus of  claim 1 , wherein said filter is at least one of embedded in an encapsulant surrounding said phosphor material, positioned on top of an encapsulant or shell surrounding said phosphor material, and positioned directly on a layer of said phosphor material.  
   
   
       21 . The lighting apparatus of  claim 1 , wherein said apparatus has a CCT of from 2500 to 7500 K.  
   
   
       22 . The lighting apparatus of  claim 21 , wherein a CCT of said apparatus is higher than 3000K.  
   
   
       23 . The lighting apparatus of  claim 1 , wherein a color point of said apparatus lies substantially on the black body locus within 0.020 units in the vertical direction on the 1931 CIE Diagram.  
   
   
       24 . A method for making a lighting apparatus for emitting white light having enhanced red-green color contrast, the method including the steps of: 
 providing a light source emitting radiation having a peak emission at from about 250 to 500 nm;    providing a phosphor material comprising: a first phosphor material having a peak emission between about 550 and 615 nm;    radiationally coupling said phosphor material to said light source, and providing a filter that prevents a portion of radiation emitted by the phosphor material from being emitted by the apparatus while substantially permitting the emission of radiation from the lighting apparatus in emission wavelengths other than between 550 and 615 nm.    
   
   
       25 . The method of  claim 24 , wherein said filter functions such that an overall emission spectrum of the lighting apparatus has a depression between about 550 and 615 nm, said depression extending to between about 5% and 25% of the highest intensity of the emission spectrum of the lighting apparatus in the region from 400 to 700 nm.