Light guides

Abstract

This invention relates to a light guide plate and methods of manufacture. The light guide plate is suitable for use in a range of applications, particularly those which require backlighting for display units, for example, liquid crystal displays. The light guide plate comprises a combination of light guide layers and one or more scattering features.

1 . A light guide plate comprising:
 a first layer of light guiding material,   a second layer of light guiding material which is mounted upon a surface of the first layer of light guiding material, and   one or more light scattering features located at the interface between the first and second layers of light guiding material.   
     
     
         2 . The light guide plate according to  claim 1 , wherein the first and second layers of light guiding material are made from transparent polymer sheet. 
     
     
         3 . The light guide plate according to  claim 1 , wherein the refractive indices of the first and second layers of light guiding material are the same or substantially the same. 
     
     
         4 . The light guide plate according to  claim 1 , wherein the refractive index of the first and second layers of light guiding material are independently of each other about 1.4 to about 1.7. 
     
     
         5 . The light guide plate according to  claim 1 , wherein the thickness of the first and second layers of light guiding material are independently of each other about 0.1 mm to about 10 mm. 
     
     
         6 . The light guide plate according to  claim 1 , wherein the refractive index of the one or more light scattering features is greater than the refractive index of the first layer of light guiding material. 
     
     
         7 . The light guide plate according to  claim 1 , wherein the one or more scattering features are dispersed within a transparent ink. 
     
     
         8 . The light guide plate according to  claim 7 , wherein the refractive index of the transparent ink is equal to or substantially equal to the refractive index of the first layer of light guiding material. 
     
     
         9 . The light guide plate according to  claim 1 , wherein the one or more scattering features are in particulate form. 
     
     
         10 . The light guide plate according to  claim 9 , wherein the particle size of the particles is in the range of about 1 μm to about 20 μm. 
     
     
         11 . The light guide plate according to  claim 9 , wherein the particles are silica particles. 
     
     
         12 . The light guide plate according to  claim 1 , wherein the refractive index of at least one of the scattering features is about 1.6 to about 2. 
     
     
         13 . A light guide device comprising a light guide plate according to  claim 1  and one or more light sources. 
     
     
         14 . The light guide device according to  claim 13 , wherein the one or more light sources are selected from LEDs, cold cathode fluorescent lamps, laser diodes, organic light emitting diode sources, and other electroluminescent devices. 
     
     
         15 . The light guide device according to  claim 14 , wherein the one or more light sources are selected from one or more LEDs. 
     
     
         16 . The light guide device according to  claim 13 , wherein the light guide device is edge-lit. 
     
     
         17 . The light guide device according to  claim 13 , wherein the one or more light sources are not encapsulated by a layer of light guiding material. 
     
     
         18 . The display device comprising the light guide device of  claim 13 . 
     
     
         19 . The display device according to  claim 18 , wherein the display device comprises a liquid crystal cell. 
     
     
         20 . A method of producing a light guide plate comprising:
 (a) applying to a surface of a first layer of light guiding material one or more light scattering features; and   (b) mounting a second layer of light guiding material on the surface of the first layer of light guiding material such that said one or more light scattering features are located at the interface between the first and second layers of light guiding material.   
     
     
         21 . The method according to  claim 20 , wherein (a) comprises applying to the surface a transparent ink comprising the scattering features, and curing the ink. 
     
     
         22 . The method according to  claim 20 , wherein an additive printing method is used to apply the one or more light scattering features. 
     
     
         23 . The method according to  claim 22 , wherein the additive printing method is a screen printing method. 
     
     
         24 . The method according to  claim 20 , wherein (b) comprises applying a liquid polymer on the surface, and curing the liquid polymer. 
     
     
         25 . The method according to  claim 20 , wherein the second light guide layer is a polymer sheet and (b) comprises laminating the polymer sheet to the first light guide layer.