Light turning device with prismatic light turning features

Abstract

A light guide device includes a light guide body and two or more pluralities of spaced-apart slits. The slits are formed by undercuts in the light guide body. Sidewalls of the slits form facets that redirect light impinging on the facets. In some embodiments, the light guide body is attached to a light source. The light source emits light that is injected into the light guide body and the slits redirect the light out of the light guide body and towards a desired target. In some embodiments, the target is a display and a first plurality of slits directs light from the light source across the light guide body and over the face of the display. A second plurality of slits then directs light out of the light guide body and towards the display.

We claim: 
     
         1 . A method for manufacturing an illumination device, comprising:
 providing a body of light propagating material, the material supporting propagation of light through a length of the body; and   forming first and second pluralities of spaced-apart undercuts in different sides the body.   
     
     
         2 . The method of  claim 1 , wherein the different sides include a first edge and a major side of the body. 
     
     
         3 . The method of  claim 2 , wherein the second plurality of undercuts are configured to redirect light, propagating from a second edge crossing the first edge, across the body of light propagating material towards a third edge opposite the first edge; and wherein the first plurality of undercuts is configured to redirect the light redirected by the second plurality of undercuts out through a second major side. 
     
     
         4 . The method of  claim 1 , wherein the different sides include a first major side of the body and a second major side of the body. 
     
     
         5 . The method of  claim 4 , wherein the first and second pluralities of undercuts are configured to redirect light, propagating from a direction of a first edge, out through the second major side. 
     
     
         6 . The method of  claim 1 , further comprising depositing an anti-reflective coating on surfaces of the undercuts. 
     
     
         7 . The method of  claim 1 , wherein forming the plurality of spaced-apart undercuts includes extruding the light propagating material through a die. 
     
     
         8 . The method of  claim 1 , wherein forming the plurality of spaced-apart undercuts includes casting the light propagating material in a mold. 
     
     
         9 . The method of  claim 1 , wherein forming the plurality of spaced-apart undercuts includes injection molding light propagating material through a mold. 
     
     
         10 . The method of  claim 1 , wherein forming the plurality of spaced-apart undercuts includes embossing the body of light propagating material. 
     
     
         11 . The method of  claim 1 , wherein forming the plurality of spaced-apart undercuts includes machining or laser ablating the body of light propagating material. 
     
     
         12 . The method of  claim 1 , further including affixing a display, the display including a plurality of pixels, to the body of light propagating material. 
     
     
         13 . The method of  claim 1 , wherein a density of at least one of the first or second spaced-apart undercuts increases with increasing distance from a light input edge of the body light propagating material. 
     
     
         14 . The method of  claim 1 , wherein a surface area of at least one of the first or second spaced-apart undercuts increases with increasing distance from a light input edge of the body light propagating material. 
     
     
         15 . The method of  claim 1 , wherein an angle formed between an undercut and the side in which the undercut is formed varies among at least one of the first or second plurality of undercuts. 
     
     
         16 . The method of  claim 1 , wherein an angle formed between an undercut and the side in which the undercut is formed varies between the first and second pluralities of undercuts. 
     
     
         17 . The method of  claim 1 , wherein a surface area of the undercuts varies between the first and second pluralities of undercuts. 
     
     
         18 . The method of  claim 1 , wherein the undercuts define spaced-apart concentric semicircles. 
     
     
         19 . A illumination device fabricated by the method of  claim 1 .