Led light engine for backlighting a liquid crystal display

Abstract

An edge-lit backlighting system for liquid crystal displays employs a number of light strips in the form of thin, light weight sections of a thermally conductive substrate each of which mounts a plurality of light engines having an array of densely packed, primary color light emitting diodes, which, when collectively illuminated, produce a white light of desired reference white chromaticity.

1 . A light strip for use in an edge-lit backlighting system employed with a liquid crystal display, comprising: 
 a thermally conductive substrate formed in an elongated strip;    a plurality of light engines mounted at spaced intervals along said elongated strip, each of said light engines including a plurality of primary color light emitting diodes, said light emitting diodes being selected so that when collectively illuminated a white light of desired reference white chromaticity is produced.    
   
   
       2 . The light strip of  claim 1  in which said thermally conductive substrate is a printed wiring board.  
   
   
       3 . The light strip of  claim 1  in which said elongated strip is formed with lines of weakness at intervals therealong in between said light engines, said elongated strip being breakable at each of said lines of weakness to allow for the formation of a shortened strip of desired length.  
   
   
       4 . The light strip of  claim 1  in which said light emitting diodes are arranged in an array on said elongated strip of at least two parallel legs, said light emitting diodes in each leg being connected in series.  
   
   
       5 . The light strip of  claim 4  in which said elongated strip has two parallel legs of light emitting diodes, each of said legs including six light emitting diodes connected in series.  
   
   
       6 . The light strip of  claim 5  in which said six light emitting diodes in each parallel leg includes three green, two red and one blue, said six light emitting diodes when collectively illuminated producing a desired reference white chromaticity.  
   
   
       7 . The light strip of  claim 1  in which said light emitting diodes of each light engine are arranged in three discrete arrays, one of said arrays having red light emitting diodes, another having green light emitting diodes and the third having blue light emitting diodes.  
   
   
       8 . The light strip of  claim 7  in which said light emitting diodes within at least one of said arrays are arranged in parallel legs with said light emitting diodes in each leg being connected in series.  
   
   
       9 . The light strip of  claim 7  in which a forward voltage and current is applied to each array of light emitting diodes in an independent manner to permit variation of the magnitude of light for each color primary in each array.  
   
   
       10 . A light strip for use in an edge-lit backlighting system employed with a liquid crystal display, comprising: 
 a thermally conductive substrate formed in an elongated strip;    plurality of light engines mounted at spaced intervals along said elongated strip, each of said light engines including a plurality of primary color light emitting diodes arranged in an array of at least two parallel legs, said light emitting diodes in each leg being connected in series, said light emitting diodes being selected so that when collectively illuminated a white light of desired reference white chromaticity is produced.    
   
   
       11 . The light strip of  claim 10  in which said elongated strip has two parallel legs of light emitting diodes, each of said legs including six light emitting diodes connected in series.  
   
   
       12 . The light strip of  claim 11  in which said six light emitting diodes in each parallel leg includes three green, two red and one blue, said six light emitting diodes when collectively illuminated producing a desired reference white chromaticity.  
   
   
       13 . The light strip of  claim 10  in which said thermally conductive substrate is a printed wiring board.  
   
   
       14 . The light strip of  claim 10  in which said elongated strip is formed with lines of weakness at intervals therealong in between said light engines, said elongated strip being breakable at each of said lines of weakness to allow for the formation of a shortened strip of desired length.  
   
   
       15 . A light strip for use in an edge-lit backlighting system employed with a liquid crystal display, comprising: 
 a thermally conductive substrate formed in an elongated strip;    a plurality of light engines mounted at spaced intervals along said elongated strip, each of said light engines including a plurality of primary color light emitting diodes arranged in three discrete arrays, a first one of said arrays having red light emitting diodes, a second one of said arrays having green light emitting diodes and a third one of said arrays having blue light emitting diodes, a voltage being applied to each of said arrays which is separately controlled to permit independent variation of the intensity of red, blue or green light produced by respective arrays, said intensity of red, green and blue light from respective arrays being selected so that when collectively illuminated a white light of desired reference white chromaticity is produced.    
   
   
       16 . The light strip of  claim 15  in which said light emitting diodes within at least one of said arrays are arranged in parallel legs with said light emitting diodes in each leg being connected in series.  
   
   
       17 . The light strip of  claim 15  in which said thermally conductive substrate is a printed wiring board.  
   
   
       18 . The light strip of  claim 15  in which said elongated strip is formed with lines of weakness at intervals therealong in between said light engines, said elongated strip being breakable at each of said lines of weakness to allow for the formation of a shortened strip of desired length.  
   
   
       19 - 26 . (canceled)