Reflective display based on liquid crystal materials

Abstract

The present invention relates to a high contrast reflective display comprising at least one substrate, at least one electrically conductive layer and at least one close-packed, ordered monolayer of domains of electrically modulated material in a fixed, preferably crosslinked, polymer matrix and a method of making the same.

1 . A high contrast reflective display comprising at least one substrate, at least one electrically conductive layer and at least one electronically modulated imaging layer, wherein said electronically modulated imaging layer comprises a close-packed, ordered monolayer of domains of electrically modulated material in a fixed polymer matrix.  
     
     
         2 . The high contrast reflective display of  claim 1  wherein said substrate is flexible.  
     
     
         3 . The high contrast reflective display of  claim 1  wherein said substrate is transparent.  
     
     
         4 . The high contrast reflective display of  claim 3  further comprising a second substrate.  
     
     
         5 . The high contrast reflective display of  claim 1  wherein said electrically conductive layer a surface conductivity of less than 10 4  ohms/sq.  
     
     
         6 . The high contrast reflective display of  claim 1  wherein said electrically conductive conductive layer comprises ITO.  
     
     
         7 . The display of  claim 1  wherein said electrically conductive layer comprises polythiophene.  
     
     
         8 . The high contrast reflective display of  claim 1  further comprising at least a second electrically conductive layer, wherein said at least one close-packed, ordered monolayer of electrically modulated material in a crosslinked polymer matrix is between said at least one electrically conductive layer and said second conductive layer.  
     
     
         9 . The high contrast reflective display of  claim 1  wherein at least one electrically conductive layer is patterned.  
     
     
         10 . The high contrast reflective display of  claim 1  further comprising a means for applying electrical field across said at least one close-packed, ordered monolayer of electrically modulated material in a fixed polymer matrix.  
     
     
         11 . The high contrast reflective display of  claim 1  wherein said electrically modulating material is a liquid crystalline material.  
     
     
         12 . The high contrast reflective display of  claim 1  wherein said electrically modulated material comprises a bistable liquid crystalline material.  
     
     
         13 . The high contrast reflective display of  claim 12  wherein said bistable liquid crystalline material comprises a chiral nematic liquid crystal layer.  
     
     
         14 . The high contrast reflective display of  claim 1  wherein said at least one close-packed, ordered monolayer of electrically modulated material is a hexagonally closest packed monolayer of light modulating material.  
     
     
         15 . The high contrast reflective display of  claim 1  wherein said at least one close-packed, ordered monolayer of electrically modulated material has a repeat pattern or periodicity with a repeat distance of the order of the wavelength of visible light.  
     
     
         16 . The high contrast reflective display of  claim 1  wherein said fixed polymer matrix is a crosslinked polymer matrix.  
     
     
         17 . The high contrast reflective display of  claim 1  wherein said fixed polymer matrix is not rigid prior to drying.  
     
     
         18 . The high contrast reflective display of  claim 1  wherein said fixed polymer matrix is in a random configuration if the coating is dried at a temperature that is above the sol-gel transition temperature.  
     
     
         19 . The high contrast reflective display of  claim 1  wherein said fixed polymer matrix prior to crosslinking has a sol-gel transition temperature or thermal gelation temperature or chill set temperature below 23° C.  
     
     
         20 . The high contrast reflective display of  claim 1  wherein said fixed polymer matrix prior to crosslinking has a sol-gel transition temperature or thermal gelation temperature or chill set temperature below 10° C.  
     
     
         21 . The high contrast reflective display of  claim 1  wherein said electrically modulated material to said fixed polymer matrix ratio is from 6:1 to 0.5:1  
     
     
         22 . The high contrast reflective display of  claim 1  wherein said electrically modulated material to said fixed polymer matrix ratio is 3:1.  
     
     
         23 . The high contrast reflective display of  claim 1  wherein said fixed polymer matrix comprises gelatin.  
     
     
         24 . The high contrast reflective display of  claim 23  wherein said gelatin is in a random coil configuration if the coating is dried at a temperature that is above the sol-gel transition temperature of gelatin.  
     
     
         25 . The high contrast reflective display of  claim 23  wherein said gelatin is fish gelatin.  
     
     
         26 . The high contrast reflective display of  claim 25  wherein said fish gelatin is deep water fish gelatin.  
     
     
         27 . The high contrast reflective display of  claim 23  wherein said gelatin has lower imino acid content than bovine gelatin.  
     
     
         28 . The high contrast reflective display of  claim 1  wherein said fixed polymer matrix further comprises a hardening agent.  
     
     
         29 . The high contrast reflective display of  claim 1  further comprising a protective layer.  
     
     
         30 . The high contrast reflective display of  claim 29  wherein said protective layer comprises gelatin.  
     
     
         31 . The high contrast reflective display of  claim 30  wherein said gelatin contains molecules in a helix configuration.  
     
     
         32 . The high contrast reflective display of  claim 1  wherein said electrically modulated imaging layer further comprises polyvinylalcohol (PVA).  
     
     
         33 . The high contrast reflective display of  claim 1  wherein said at least one electronically modulated imaging layer has a RMS surface roughness of less than 1.5 microns  
     
     
         34 . The high contrast reflective display of  claim 1  comprising a stack of at least two of said high contrast reflective displays, wherein a stack comprises at least one substrate, at least one electrically conductive layer and at least one close-packed, ordered monolayer of domains of electrically modulated material in a fixed polymer matrix.  
     
     
         35 . A method of making a high contrast reflective display comprising: 
 providing a substrate;    applying a conductive layer;    applying at least one layer of domains of electrically modulated material in a polymer matrix;    drying the at least one applied layer of said domains of electrically modulated material in a polymer matrix at a temperature above the chill set temperature or sol-gel transition temperature of said polymer matrix to permit self-assembly of said domains of electrically modulated material into a close-packed monolayer of said domains of electrically modulated material; and fixing said polymer matrix to preserve said close-packed monolayer of domains of electrically modulated material.    
     
     
         36 . The method of  claim 35  further comprising: 
 applying a second aqueous layer containing gelatin;    chill setting said second aqueous layer containing gelatin; and    drying said second aqueous layer.