Liquid Crystal Paper

Abstract

Disclosed is liquid crystal paper and an erasing device that is not permanently connected to the liquid crystal paper. A sheet of liquid crystal paper includes flexible polymeric substrates. A polymer network or a spacer network, in which bistable cholesteric reflective liquid crystal material is dispersed, is disposed between two of the substrates. Optional alignment layers or optional electrically conductive layers sandwich the liquid crystal material therebetween. An optional layer of light absorbing material is disposed near one of the substrates. Application of pressure to an upper substrate changes a focal conic nonreflective texture of the liquid crystal material to a reflective planar texture. The erasing device applies a voltage or heat for erasing the paper by changing the reflective planar texture to the focal conic nonreflective texture.

1 - 25 . (canceled) 
     
     
         26 . Liquid crystal paper in combination with a separate erasing device for erasing the liquid crystal paper with heat comprising:
 a sheet of liquid crystal paper comprising:
 flexible polymeric substrates; 
 a polymer network or a spacer network in which bistable cholesteric reflective liquid crystal material is dispersed, disposed between two of said substrates; 
 a layer of light absorbing material disposed near one of said substrates; 
 wherein application of pressure to an upper said substrate changes a focal conic nonreflective texture of said liquid crystal material to a reflective planar texture; and 
   an erasing device for erasing said liquid crystal paper that is not permanently connected to said liquid crystal paper, said erasing device applying heat effective to cause said liquid crystal material to reach a clearing temperature such that after said liquid paper cools it returns to said focal conic nonreflective texture.   
     
     
         27 . The liquid crystal paper and separate erasing device of  claim 26  wherein all of said substrates that are upstream of said light absorbing layer in a direction of incident light are transparent. 
     
     
         28 . The liquid crystal paper and separate erasing device of  claim 26  wherein said polymer network in which said liquid crystal material is dispersed is in the form of a liquid crystal layer. 
     
     
         29 . The liquid crystal paper and separate erasing device of  claim 28  comprising at least two of said liquid crystal layers. 
     
     
         30 . The liquid crystal paper and separate erasing device of  claim 28  wherein said liquid crystal layer has a thickness ranging from 2 to 10 microns. 
     
     
         31 . The liquid crystal paper and separate erasing device of  claim 26  comprising alignment layers that sandwich said liquid crystal material therebetween, said alignment layers favoring formation of a focal conic nonreflective texture in said liquid crystal material. 
     
     
         32 . The liquid crystal paper and separate erasing device of  claim 31  wherein said alignment layers are part of said polymer network. 
     
     
         33 . The liquid crystal paper and separate erasing device of  claim 26  wherein there is no alignment layer favoring formation of said focal conic nonreflective texture in said liquid crystal material. 
     
     
         34 . The liquid crystal paper and separate erasing device of  claim 26  wherein each said substrate has a thickness ranging from 12.5 μm to 200 μm. 
     
     
         35 . The liquid crystal paper and separate erasing device of  claim 26  comprising a stylus for applying said pressure that is untethered to said liquid crystal paper or to said erasing device, said stylus containing no lead or ink. 
     
     
         36 . The liquid crystal paper and separate erasing device of  claim 26  comprising a plurality of said sheets of said liquid crystal paper and a document feeder that feeds individual said sheets to said erasing device.