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 density and/or orientation across the surface of a light guide varies to improve light emission uniformity and to reduce visual artifacts.

1 . 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 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 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 predominantly geometric light redirectors of a first group, 
 a second region including predominantly 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, 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 
 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. 
 
   
   
   
       2 . 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. 
   
   
       3 . 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. 
   
   
       4 . The light guide of  claim 1 , wherein the plurality of light redirectors have a triangular cross section. 
   
   
       5 . The light guide of  claim 1 , wherein the plurality of light redirectors have 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 varying shapes. 
   
   
       8 . The light guide of  claim 1 , wherein the geometric light redirectors in the first group have varying dimensions. 
   
   
       9 . The light guide of  claim 1 , wherein substantially perpendicular comprises being within plus or minus 20 degrees of perpendicular. 
   
   
       10 . 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. 
   
   
       11 . The light guide of  claim 1 , comprising a first light source positioned adjacent the first light introduction position and a second light source positioned adjacent the second light introduction position. 
   
   
       12 . The light guide of  claim 11 , wherein the first and second light sources comprise light emitting diodes. 
   
   
       13 . The light guide of  claim 11 , wherein the first and second light sources comprise multi-colored light emitting diode modules. 
   
   
       14 . The light guide of  claim 11 , wherein the front face of at least one of the plurality of light redirectors has a dimension less than about 500 microns. 
   
   
       15 . The light guide of  claim 1 , wherein geometric light redirectors of the first group increase in height with distance from the first light introduction position and geometric light redirectors of the second group increase in height with distance from the second light introduction position. 
   
   
       16 . A light guide of a display, comprising:
 a first light introduction position on an edge of the light guide, and   a plurality of geometric light redirectors distributed across a surface of the light guide for redirecting light introduced at the first light introduction position, wherein the density of geometric light redirectors, beginning at a first distance from the first light introduction position, along at least one direction extending radially from the first light introduction position, decreases in a gradual fashion.   
   
   
       17 . The light guide of  claim 16 , comprising a second light introduction position. 
   
   
       18 . The light guide of  claim 17 , wherein the first light introduction position is on the same edge of the light guide as the second light introduction position. 
   
   
       19 . The light guide of  claim 17 , 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. 
   
   
       20 . The light guide of  claim 17 , wherein the direction in which the density of light directors decreases is at least partially towards the second light introduction position. 
   
   
       21 . The light guide of  claim 17 , comprising a second plurality of light redirectors distributed across the surface of the light guide for redirecting light introduced through the second light introduction position. 
   
   
       22 . The light guide of  claim 16 , wherein the plurality of light redirectors have a triangular cross section. 
   
   
       23 . The light guide of  claim 16 , wherein the plurality of light redirectors have a trapezoidal cross section. 
   
   
       24 . The light guide of  claim 16 , wherein the plurality of light redirectors have a rounded cross section. 
   
   
       25 . The light guide of  claim 17 , comprising a first light source positioned adjacent the first light introduction position and a second light source positioned adjacent the second light introduction position. 
   
   
       26 . The light guide of  claim 25 , wherein the first and second light sources comprise light emitting diodes. 
   
   
       27 . The light guide of  claim 25 , wherein the first and second light sources comprise multi-colored light emitting diode modules. 
   
   
       28 . The light guide of  claim 16 , wherein the front face of at least one of the plurality of light redirectors has a dimension less than about  500  microns. 
   
   
       29 . The light guide of  claim 16 , wherein the height of geometric light redirectors increases with distance from the first light introduction position. 
   
   
       30 . A light guide of a display, comprising:
 a front surface, a rear surface, and at least first, second, and third edges separating the front and rear surfaces;   at least one light introduction position on the first edge;   reflective surfaces positioned proximate the second and third edges and directed towards an interior of the light guide;   a plurality of first geometric light redirectors distributed across one of the front surface and the rear surface, wherein
 a front face of each first geometric light redirector is oriented substantially towards the first edge, 
   a plurality of second geometric light redirectors distributed across the one of the front surface and the rear surface, wherein a front face of each second geometric light redirector is oriented at least partially towards one of the second and third edges.   
   
   
       31 . The light guide of  claim 30 , wherein the plurality of first and second light redirectors have a triangular cross section. 
   
   
       32 . The light guide of  claim 30 , wherein the plurality of first and second light redirectors have a trapezoidal cross section. 
   
   
       33 . The light guide of  claim 30 , wherein the plurality of first and light redirectors have a rounded cross section. 
   
   
       34 . The light guide of  claim 30 , wherein the height of geometric light redirectors increases with distance from the first light introduction position. 
   
   
       35 . The light guide of  claim 30 , wherein a front face of each of the first geometric light redirectors intersects with the one of the front surface and the rear surface along an intersection line, and the intersection line of each geometric light redirector is substantially perpendicular to a line connecting a midpoint of the intersection line with one of the at least one light introduction position. 
   
   
       36 . The light guide of  claim 30 , wherein a front face of each of the first geometric light redirectors intersects with the one of the front surface and the rear surface along an intersection line, and the intersection line of each geometric light redirector is substantially parallel to the first edge.