Edge-lit waveguide illumination systems employing light converting layers

Abstract

An illumination system having a plurality of light emitting diodes (LEDs) and multiple layers of optical elements used to distribute light emitted by the LEDs. The optical elements may include a planar optical waveguide, a plurality of non-imaging lenses, a two-dimensional pattern of light extraction elements, a reflective surface, a light diffusing layer. The illumination system may further have a plurality of luminescent centers distributed in a volume of a planar layer of an optically transmissive material or one or more light converting elements used for converting light.

What is claimed is: 
     
         1 . An edge-lit light converting waveguide illumination system, comprising:
 a planar optical waveguide having a rectangular shape, a light input edge configured for receiving light, a front surface configured for both receiving and distributing light, an opposing back surface extending parallel to the front surface and configured for both receiving and distributing light, a length dimension greater than a thickness dimension by at least 40 times, and a width dimension greater than the thickness dimension by at least 20 times;   a plurality of light extraction surface structures distributed over an area of the planar optical waveguide according to a two-dimensional pattern;   a plurality of luminescent centers distributed in a volume of a planar layer of an optically transmissive material which is approximately coextensive with the planar optical waveguide;   a plurality of light emitting diodes arranged along the light input edge and configured to emit monochromatic light towards the light input edge;   a sheet of reflective material approximately coextensive with the planar optical waveguide and positioned on a back side of the planar optical waveguide;   a light diffusing layer approximately coextensive with the planar optical waveguide; and   a prismatic surface portion extending generally parallel to the planar optical waveguide and including a continuous series of grooves disposed side by side and each having a triangular cross-section,   wherein the luminescent centers are configured to absorb light in a first wavelength and re-radiate at least some of the energy of the absorbed light as scattered light in a second wavelength which is longer than the first wavelength, and wherein the planar layer is configured to emit at least a portion of light re-radiated by the luminescent centers.   
     
     
         2 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , comprising a parallel array of linear cylindrical lenses formed in the front surface and longitudinally extending between two opposite edges of the planar optical waveguide, wherein an area of each of the linear cylindrical lenses is greater than an area of each of the light extraction surface structures, and wherein the optical waveguide is configured to distribute light from the parallel array of linear cylindrical lenses. 
     
     
         3 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , comprising a parallel array of linear cylindrical lenses formed in the front surface and longitudinally extending between two opposite edges of the planar optical waveguide, wherein an area of each of the linear cylindrical lenses is greater than an area of each of the light extraction surface structures, wherein the optical waveguide is configured to distribute light from the parallel array of linear cylindrical lenses, and wherein a focal length characterizing at least one of the linear cylindrical lenses is less than a thickness of the planar optical waveguide. 
     
     
         4 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein the planar optical waveguide is formed from a flexible material and retained in a bent or curved configuration. 
     
     
         5 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein at least one of the plurality of light extraction surface structures comprises a surface cavity having a curved wall, which is configured to deflect light using both total internal reflection and refraction. 
     
     
         6 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein at least some of the light extraction surface structures have randomized positions within the two-dimensional pattern, and wherein the planar optical waveguide is configured to emit a uniform flux of light from the front surface. 
     
     
         7 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein the planar layer is sandwiched between two films of a different optically transmissive material and forms a monolithic structure with the two films. 
     
     
         8 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein the planar layer is sandwiched between two optically transmissive films having a different refractive index than the planar layer, and wherein the planar layer and the optically transmissive films form a monolithic structure. 
     
     
         9 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein at least some of the plurality of light extraction surface structures comprise a surface groove aligned parallel to an edge of the planar optical waveguide. 
     
     
         10 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein at least one of the plurality of light extraction surface structures is configured to deflect at least some light using total internal reflection and direct the deflected light towards the front surface at an angle of less than 42 degrees with respect to a normal to the back surface. 
     
     
         11 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein at least one of the plurality of light extraction surface structures comprises a light scattering material and has a textured surface. 
     
     
         12 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , further comprising one or more photoresponsive elements disposed in an energy receiving relationship with respect to the planar optical waveguide. 
     
     
         13 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , wherein at least one of the light emitting diodes is a side-emitting LED attached to a planar finless heat sink, which is oriented parallel to the planar optical waveguide and comprises a layer of a metallic material, and wherein a light emitting surface of the side-emitting LED is oriented perpendicular to a prevalent plane of the planar finless heat sink. 
     
     
         14 . An edge-lit light converting waveguide illumination system as recited in  claim 1 , further comprising a reflective film laminated to an edge of the planar optical waveguide which opposite to the light input edge. 
     
     
         15 . A light converting illumination system, comprising:
 a plurality of light emitting diodes;   a planar two-dimensional array of non-imaging lenses configured to distribute light emitted by the light emitting diodes;   a planar light converting layer extending parallel to the planar two-dimensional array of non-imaging lenses, the planar light converting layer having a rectangular shape, a first wall, an opposing second wall extending parallel to the first wall, a length dimension greater than a thickness dimension by at least 40 times, and a width dimension greater than the thickness dimension by at least 20 times;   a plurality of luminescent centers distributed in a volume of the planar light converting layer and configured to absorb light in a first wavelength and re-radiate at least some of the energy of the absorbed light as scattered light in a second wavelength which is longer than the first wavelength; and   a sheet of reflective material approximately coextensive with the two-dimensional array of non-imaging lenses,   wherein the planar light converting layer is configured to emit at least a portion of light re-radiated by the luminescent centers.   
     
     
         16 . An edge-lit light converting waveguide illumination system, comprising:
 a planar optical waveguide having a rectangular shape, a light input edge configured for receiving light, a front surface configured for both receiving and distributing light, an opposing back surface extending parallel to the front surface and configured for both receiving and distributing light, a length dimension greater than a thickness dimension by at least 40 times, and a width dimension greater than the thickness dimension by at least 20 times;   a plurality of light extraction surface structures distributed over an area of the planar optical waveguide according to a two-dimensional pattern;   a plurality of light emitting diodes arranged along the light input edge and configured to emit light towards the light input edge;   a sheet of reflective material approximately coextensive with the planar optical waveguide and positioned on a back side of the planar optical waveguide;   a light diffusing layer approximately coextensive with the planar optical waveguide;   a prismatic surface portion extending generally parallel to the planar optical waveguide and including a continuous series of grooves disposed side by side and each having a triangular cross-section; and   a planar finless heat sink oriented parallel to the planar optical waveguide and comprising a layer of a metallic material,   wherein at least one of the light emitting diodes is a side-emitting LED attached to the planar finless heat sink and having a light emitting surface which is oriented perpendicular to a prevalent plane of the planar finless heat sink.   
     
     
         17 . An edge-lit light converting waveguide illumination system as recited in  claim 16 , comprising a parallel array of linear cylindrical lenses formed in the front surface and longitudinally extending between two opposite edges of the planar optical waveguide, wherein an area of each of the linear cylindrical lenses is greater than an area of each of the light extraction surface structures, wherein the optical waveguide is configured to distribute light from the parallel array of linear cylindrical lenses, and wherein a focal length characterizing at least one of the linear cylindrical lenses is less than a thickness of the planar optical waveguide. 
     
     
         18 . An edge-lit light converting waveguide illumination system as recited in  claim 16 , wherein the planar optical waveguide is formed from a flexible material and retained in a bent or curved configuration. 
     
     
         19 . An edge-lit light converting waveguide illumination system as recited in  claim 16 , further comprising one or more light converting elements disposed in an energy receiving relationship with respect to the planar optical waveguide. 
     
     
         20 . An edge-lit light converting waveguide illumination system as recited in  claim 16 , wherein at least some of the light extraction surface structures have randomized positions within the two-dimensional pattern, and wherein the planar optical waveguide is configured to emit a uniform flux of light from the front surface.