Transflective liquid crystal displays

Abstract

A transflective liquid crystal display ( 70 ) comprises a liquid crystal cell ( 38 ) disposed between a front substrate ( 40 ) and a rear substrate ( 36 ), a front polariser ( 46 ) located in front of the front substrate ( 40 ) and a rear polariser ( 32 ) located behind the rear substrate ( 36 ), a front retarder ( 42, 44 ) located between the front substrate ( 40 ) and the front polariser ( 46 ), a rear retarder ( 62, 64 ) located between the rear substrate ( 36 ) and the rear polariser ( 32 ), and a light source ( 30 ) located behind the rear polariser ( 32 ). A transflective display having a number of differently coloured sequentially flashing backlights is also provided.

1 - 37 . (canceled) 
   
   
       38 . A transflective liquid crystal display comprising:
 a liquid crystal disposed between a front substrate and a rear substrate,   a front polariser located in front of the front substrate and rear polariser located behind the rear substrate,   a front retarder located between the front substrate and the front polariser, and   a rear retarder located between the rear substrate and the rear polariser, and addressing means for addressing each pixel and switching each pixel between different states resulting in different levels of transmission of light through the display, characterised in that,   a light source is located behind the rear polariser, and   the liquid crystal display is provided with a rear electrode which is partially reflective and partially transmissive and the liquid crystal is divided into a plurality of pixels.   
   
   
       39 . A transflective display as claimed in  claim 38 , wherein the front retarder is an achromatic combination retarder. 
   
   
       40 . A transflective display as claimed in  claim 38 , wherein the front retarder comprises a front halfwave plate and a front quarterwave plate. 
   
   
       41 . A transflective display as claimed in  claim 40 , wherein the front quarterwave plate has a slow axis substantially parallel or normal to a bisectrix of surface alignment directions of the liquid crystal, such that a retardation of the front quarterwave plate, in conjunction with the retardation of the liquid crystal, produces in one state circular polarised light after a single pass. 
   
   
       42 . A transflective display as claimed in  claim 40 , wherein the front quarterwave plate has a slow axis substantially parallel or normal to a bisetrix of surface alignment directions of the liquid crystal, such that a retardation of the front quarterwave plate, in conjunction with the retardation of the liquid crystal, produces in a second state linear polarised light after a single pass. 
   
   
       43 . A transflective display as claimed in  claim 40 , wherein the front quarterwave plate has a retardation of between 50 nm and 250 nm. 
   
   
       44 . A transflective display as claimed in  claim 38 , wherein the rear retarder comprises a rear quarterwave plate. 
   
   
       45 . A transflective display as claimed in  claim 44 , wherein the rear quarterwave plate has a slow axis substantially parallel or normal to a bisetrix of surface alignment directions of the liquid crystal, such that a retardation of the rear quarterwave plate, in conjunction with the retardation of the liquid crystal and the front quarterwave plate, produces in one state circular polarised light after a single pass. 
   
   
       46 . A transflective display as claimed in  claim 44 , wherein the rear retarder comprises a rear quarterwave plate, and the rear quarterwave plate has a slow axis substantially parallel or normal to a bisetrix of surface alignment directions of the liquid crystal, such that a retardation of the rear quarterwave plate, in conjunction with the retardation of the liquid crystal and the front quarterwave plate, produces in a second state linear polarised light after a single pass. 
   
   
       47 . A transflective display as claimed in  claim 44 , wherein the rear quarterwave plate has a retardation of between 100 nm and 180 nm. 
   
   
       48 . A transflective display as claimed in  claim 38 , wherein the rear substrate is provided with a partially reflective and partially transmissive mirror. 
   
   
       49 . A transflective display as claimed in  claim 38 , wherein the rear retarder further comprises a rear halfwave plate. 
   
   
       50 . A transflective display as claimed in  claim 44 , wherein the rear retarder further comprises a rear halfwave plate and the rear halfwave plate is located between the rear quarterwave plate and the rear polariser. 
   
   
       51 .- 84 . (canceled)