Display

Abstract

The present invention relates to display, in particular to a liquid crystal display illuminated by ambient light. The display has a display area, and a light guide system for providing light to the display area, the light guide system comprising: a planar light guiding layer comprised of liquid crystal material and having a light emitting surface and a plurality of side faces disposed around the light emitting surface; a plurality of light pipes, each light pipe having a collector end for collecting ambient light and an output end, the output ends being arranged along the side faces of the light guiding layer so as to introduce the collected light into the guiding medium. The output ends of the light pipes are distributed evenly along each side face of the light guiding layer so as to provide homogeneous illumination to the display area.

What is claimed is:  
     
         1 . A display comprising: 
 a display area; and    a light guide for providing light to the display area, the light guide comprising: 
 a planar light guiding medium formed of liquid crystal material and having a light emitting surface and one or more side faces disposed around the light emitting surface;  
 a plurality of light pipes, each light pipe having a collector end for collecting light and an output end, the output ends being arranged along the side faces so as to introduce the collected light into the guiding medium;  
 wherein the output ends of the light pipes are distributed along the or each side face.  
   
     
     
         2 . A display as claimed in  claim 1 , wherein the collector ends of the light pipes are distributed over a light collecting area and wherein the position of the collector ends on the light collecting area is scrambled relative to the position of the corresponding output ends on the side faces of the light guiding medium.  
     
     
         3 . A display as claimed in  claim 1 , wherein the light guiding medium has a planar back surface, and wherein a reflecting layer is provided on the back surface of the light guiding medium.  
     
     
         4 . A display as claimed in  claim 1 , wherein: 
 means are provided for applying an electrical signal to the guiding medium in one or more localised areas; and,    the guiding medium is responsive to the electrical signal such that the optical properties of the optical medium are changed in each localised area where the electrical signal is applied, with the result that in the localised areas where the electrical signal is applied, light travelling along the guiding medium exits the guiding medium through the light emitting surface, and where the electrical signal is not applied, light within the light guiding medium is channelled therealong.    
     
     
         5 . A display as claimed in  claim 4 , wherein a quarter wave plate is provided at the output of each light pipe.  
     
     
         6 . A display as claimed in  claim 1 , wherein the light pipes are formed from optic fibres.  
     
     
         7 . A display comprising: 
 a display area;    a light guide for providing light to the display area; and    a plurality of electrodes for addressing localised areas of the liquid crystal light guide, wherein: 
 the light guide comprises a planar light guiding medium formed of liquid crystal material having a light emitting surface and one or more side faces disposed around the light emitting surface, a plurality of light pipes, each light pipe having a collector end for collecting light and an output end, the output ends being arranged along the side faces so as to introduce the collected light into the guiding medium, wherein the output ends of the light pipes are distributed along the or each side face;  
 the plurality of electrodes are adapted to apply a switching electric field across the guiding medium at said localised areas such that the optical properties of the optical medium are changed where the switching electric field is applied such as to cause light traveling along the guiding medium to exit the guiding medium through the light emitting surface, whereas if the switching field is not applied, light within the light guiding medium is channeled therealong.  
   
     
     
         8 . A light guide for providing light to a display area, comprising: 
 a planar light guiding medium being of a liquid crystal material and having a light emitting surface and one or more side faces disposed around the light emitting surface;    a plurality of light pipes, each light pipe having a collector end for collecting light and an output end, the output ends being arranged along the side faces so as to introduce the collected light into the guiding medium;    wherein the output ends of the light pipes are distributed evenly along the or each side face.