Light guides and backlight systems incorporating light redirectors at varying densities

Abstract

Light guides and backlight systems are disclosed that include one or more groups of geometric light redirectors whose arrangement and/or orientation across the surface of a light guide varies to improve light emission uniformity and to reduce visual artifacts.

What is claimed is: 
     
         1 . A light guide comprising:
 a front surface, a rear surface, and at least one edge separating the front and rear surfaces;   a first light introduction position on one of the at least one edge;   a second light introduction position on one of the at least one edge spaced away from the first light introduction position; and   a plurality of geometric light redirectors distributed amongst at least two regions of one of the front surface and the rear surface of the light guide, wherein a front face of each geometric light redirector intersects with the one of the front surface and the rear surface along an intersection line, the at least two regions including:
 a first region including geometric light redirectors of a first group, 
 a second region including geometric light redirectors of a second group, wherein:
 the intersection line of each geometric light redirector of the first group is substantially perpendicular to a line connecting a midpoint of the intersection line with the first light introduction position, 
 the intersection line of each geometric light redirector of the second group is substantially perpendicular to a line connecting a midpoint of the intersection line with the second light introduction position, 
 wherein a height of each light redirector of the first group of geometric light redirectors increases as distance from the first light introduction position increases, and 
 wherein a height of each light redirector of the second group of geometric light redirectors increases as distance from the second light introduction position increases. 
 
   
     
     
         2 . The light guide of  claim 1 , wherein the plurality of geometric light redirectors are distributed amongst three regions, wherein a third region includes geometric light redirectors of the first and second groups distributed substantially throughout. 
     
     
         3 . The light guide of  claim 1 , wherein the first light introduction position and the second light introduction position are on the same edge of the light guide. 
     
     
         4 . The light guide of  claim 1 , wherein the first light introduction position is on a first edge of the light guide and the second light introduction position is on a second edge of the light guide. 
     
     
         5 . The light guide of  claim 1 , wherein the plurality of light redirectors have a triangular cross-section or a trapezoidal cross-section. 
     
     
         6 . The light guide of  claim 1 , wherein the intersection line of at least one light redirector is curved. 
     
     
         7 . The light guide of  claim 1 , wherein the geometric light redirectors in the first group have at least one of varying shapes and varying dimensions. 
     
     
         8 . The light guide of  claim 1 , wherein substantially perpendicular includes being within plus or minus 20 degrees of perpendicular. 
     
     
         9 . The light guide of  claim 1 , wherein the plurality of geometric light redirectors in the first group have a varying density on the one of the front and rear surfaces and the density varies as a function of distance from the first light introduction position. 
     
     
         10 . The light guide of  claim 1 , further comprising a first light source positioned adjacent the first light introduction position and a second light source positioned adjacent the second light introduction position. 
     
     
         11 . The light guide of  claim 10 , wherein the first and second light sources include light emitting diodes. 
     
     
         12 . The light guide of  claim 10 , wherein the light emitting diodes include multi-colored light emitting diode modules. 
     
     
         13 . The light guide of  claim 1 , wherein the front face of at least one of the plurality of light redirectors has a dimension less than about  500  microns. 
     
     
         14 . A light guide of a display comprising:
 a front surface, a rear surface, and at least one edge separating the front and rear surfaces;   a first light introduction position on one of the at least one edge;   a plurality of geometric light redirectors distributed across the one of the front surface and the rear surface, wherein
 the at least one edge includes first, second, and third edges separating the front and rear surfaces, 
 at least one of the first and second light introduction positions is on the first edge, and 
 a front face of each of a portion of the plurality of geometric light redirectors is oriented at least partially towards one of the second and third edges; and 
   reflective surfaces positioned proximate the second and third edges and directed towards an interior of the light guide.   
     
     
         15 . The light guide of  claim 14 , further comprising a second light introduction position on one of the at least one edge spaced away from the first light introduction position. 
     
     
         16 . The light guide of  claim 15 , wherein the plurality of geometric light redirectors are distributed amongst three regions of one of the front surface and the rear surface of the light guide, wherein a front face of each geometric light redirector intersects with the one of the front surface and the rear surface along an intersection line, the three regions including:
 a first region including geometric light redirectors of a first group,   a second region including geometric light redirectors of a second group, and   a third region including geometric light redirectors of the first group distributed substantially throughout and geometric light redirectors of the second group distributed substantially throughout.   
     
     
         17 . The light guide of  claim 16 , wherein the intersection line of each geometric light redirector of the first group is substantially perpendicular to a line connecting a midpoint of the intersection line with the first light introduction position and wherein the intersection line of each geometric light redirector of the second group is substantially perpendicular to a line connecting a midpoint of the intersection line with the second light introduction position. 
     
     
         18 . The light guide of  claim 14 , wherein a height of each light redirector of the plurality of geometric light redirectors increases as distance from the first light introduction position increases. 
     
     
         19 . A method of manufacturing a light guide, comprising:
 providing the light guide, the light guide including a front surface, a rear surface, and at least one edge separating the front and rear surfaces;   forming a first light introduction position on one of the at least one edge;   forming a second light introduction position on at least one edge and spaced away from the first light introduction position; and   forming a plurality of geometric light redirectors on one of the front surface and the rear surface within the light guide, wherein:
 a front face of each geometric light redirector intersects with the one of the front surface and the rear surface along an intersection line; 
 the plurality of geometric light redirectors are arranged to redirect light from at least one of the first and second light introduction positions toward the front surface; 
 the plurality of geometric light redirectors include a first group of geometric light redirectors, the intersection line of each geometric light redirector of the first group of light redirectors being substantially perpendicular to a line connecting a midpoint of the intersection line with the first light introduction position, wherein a height of each light redirector of the first group of geometric light redirectors increases as distance from the first light introduction position increases; and 
 the plurality of geometric light redirectors include a second group of geometric light redirectors, the intersection line of each geometric light redirector of the second group of light redirectors being substantially perpendicular to a line connecting a midpoint of the intersection line with the second light introduction position, wherein a height of each light redirector of the second group of geometric light redirectors increases as distance from the second light introduction position increases. 
   
     
     
         20 . The method of manufacturing of  claim 19 , further comprising forming a first region within the light guide wherein the geometric light redirectors associated with the first group and the geometric light redirectors associated with the second group are intermixed such that a line connecting a midpoint of the intersection line of at least one geometric light redirector of the first group with the first light introduction position intersects a line connecting a midpoint of the intersection line of at least one geometric light redirector of the second group with the second light introduction position.