Side-emitting led light source for backlighting applications

Abstract

Disclosed is a side-emitting light device comprising two sub-assemblies which are optically bonded together. Each sub-assembly comprises a substrate, at least one light source disposed on the substrate, and a luminescent plate optically bonded with the at least one light source. The light source emits light of a wavelength capable of exciting luminescence light from the luminescent plate. The two sub-assemblies are arranged having the free surface of the luminescent plates facing each other. The side-emitting light device is for instance applicable for light sources comprising naked dies arranged with Thin Film Flip Chip (TFFC) technique or laser diodes.

1 . A side-emitting light device comprising:
 a first sub-assembly, said first sub-assembly having
 a first substrate; 
 at least one light source disposed on said first substrate; 
 a first luminescent plate having a first surface and an opposite second surface,
 wherein said first surface is in optical alignment with said at least one light source of said first sub-assembly, and 
 wherein said at least one light source of said first sub-assembly emits light of a wavelength capable of exciting luminescence light from said first luminescent plate; 
 
   a second sub-assembly, said second sub-assembly having
 a second substrate; 
 at least one light source disposed on said second substrate; 
 a second luminescent plate having a first surface and an opposite second surface,
 wherein said first surface is in optical alignment with said at least one light source of said second sub-assembly; 
 wherein said at least one light source of said second sub-assembly emits light of a wavelength capable of exciting luminescence light from said second luminescent plate; 
 
   wherein said first and said second sub-assembly are arranged in a face to face relationship so that said at least one light source on said first substrate is facing said at least one light source on said second substrate.   
     
     
         2 . The device according to  claim 1 , wherein said first and said second sub-assembly luminescent plate is a luminescent ceramic platelet. 
     
     
         3 . The device according to  claim 2 , wherein said at least one light source of said first and said second sub-assembly is a naked light emitting diode die. 
     
     
         4 . The device according to  claim 2 , wherein said at least one light source of said first and said second sub-assembly is formed by a laser diode. 
     
     
         5 . The device according to  claim 1  further comprising a wavelength specific optical layer arranged in optical alignment with said light sources one of said first or said second sub-assembly. 
     
     
         6 . The device according to  claim 5  wherein said wavelength specific optical layer is transparent for light generated by said light source and reflecting for light generated in the luminescent plate of said first or said second sub-assembly. 
     
     
         7 . The device according to  claim 1  further comprising a heat sink arranged in a U-shaped connection with said first and said second substrates. 
     
     
         8 . The device according to  claim 1  wherein said first and said second substrates are opaque or reflecting. 
     
     
         9 . A side-emitting light device comprising:
 a first sub-assembly, said first sub-assembly having
 a first substrate; 
 at least one light source disposed on said first substrate; 
 a first luminescent plate having a light entry surface adjacent said at least one light source and an opposite second surface, and a first side and a second side;
 wherein said light entry surface is in optical alignment with said at least one light source of said first sub-assembly, and 
 wherein said at least one light source of said first sub-assembly causes light to be generated from said plate, said generated light at a longer wavelength than at said light entry surface; 
 
   a second sub-assembly, said second sub-assembly having
 a second substrate; 
 at least one light source disposed on said second substrate; 
 a second luminescent plate having a light entry surface adjacent said at least one light source and an opposite second surface, and a first side and a second side;
 wherein said light entry surface is in optical alignment with said at least one light source of said second sub-assembly, and 
 wherein said at least one light source of said second sub-assembly causes light to be generated from said plate, said generated light at a longer wavelength than at said light entry surface; 
 
   wherein said generated light from said first subassembly exits said first luminescent plate through said first and said second side; and   wherein said generated light from said second subassembly exits said second luminescent plate through said first and said second side.   
     
     
         10 . The side-emitting light device of  claim 9  wherein said first subassembly and said second subassembly are bonded together in face to face relationship with a layer of optical binding glue. 
     
     
         11 . The side-emitting light device of  claim 10  further comprising a wavelength specific optical layer in at least one of said first and said second subassembly. 
     
     
         12 . The side-emitting light device of  claim 11  wherein said wavelength specific optical layer is adjacent said at least one light source of said at least one of said first and said second subassembly. 
     
     
         13 . A side emitting light device, comprising:
 a first and a second subassembly, each of said first and said second subassembly including:   a first substrate;   at least one light source disposed on said first substrate;   a first luminescent plate having a light entry surface adjacent said at least one light source and an opposite second surface, and a first side and a second side;   wherein said light entry surface is in optical alignment with said at least one light source of said first sub-assembly, and   wherein said at least one light source of said first sub-assembly causes light to be generated from said plate, said generated light at a longer wavelength than at said light entry surface;   a wavelength specific layer at least one light source and effective to allow light generated from said at least one light source to pass through and acting as a wavelength specific mirror reflecting light generated from said first luminescent plate;   wherein said generated light from said first luminescent plate exits said first luminescent plate through said first and said second side.