Reverse reflectance mode direct-view liquid crystal display employing a liquid crystal having a characteristic wavelength in the non-visible spectrum

Abstract

Disclosed are various reverse-mode direct-view liquid crystal displays (LCD) employing a liquid crystal having a characteristic wavelength in the non-visible spectrum, including reflective and transflective mode displays, and methods of fabrication. In accordance with the principles disclosed, a reflectance mode direct-view LCD includes a polarizer, a reflector, and a cholesteric liquid crystal (CLC) packed between the polarizer and reflector and having a characteristic wavelength to reflect non-visible spectrum. Portions of the CLC can selectively exhibit a planar state or a focal-conic state, the portions of the CLC in the planar state appearing black, and the portions of the CLC in the focal-conic state appearing white to an observer of the LCD. A transflective mode LCD is derived by further combination of polarizers, transflective mirrors and internal light sources.

What is claimed is:  
     
         1 . A direct-view liquid crystal display (LCD), comprising: 
 a polarizer;    a reflector; and    a cholesteric liquid crystal (CLC) located in a gap between said polarizer and reflector such that said CLC receives light reflected from said reflector, said CLC having a characteristic wavelength in the non-visible spectrum and capable of exhibiting a planar state or a focal-conic state.    
     
     
         2 . The direct-view LCD recited in  claim 1  wherein said CLC comprises a mixture of a nematic liquid crystal and a chiral dopant.  
     
     
         3 . The direct-view LCD recited in  claim 2  wherein said mixture comprises about 60 percent to about 90 percent by weight of said nematic liquid crystal and a balance of said mixture comprising said chiral dopant.  
     
     
         4 . The direct-view LCD recited in  claim 1  wherein said gap ranges from about 1 micron to about 6 microns.  
     
     
         5 . The direct-view LCD recited in  claim 1  wherein said gap ranges from about 2 microns to about 3 microns.  
     
     
         6 . The direct-view LCD recited in  claim 1  wherein said LCD further includes an alignment coating material.  
     
     
         7 . The direct-view LCD recited in  claim 6  wherein said alignment coating material comprises a polyimide.  
     
     
         8 . The direct-view LCD recited in  claim 1  wherein said characteristic wavelength of said CLC is in the infrared spectrum.  
     
     
         9 . The direct-view LCD recited in  claim 8  wherein said characteristic wavelength of said CLC is greater than about 780 nm.  
     
     
         10 . The direct-view LCD recited in  claim 8  wherein said characteristic wavelength of said CLC is greater than about 700 nm.  
     
     
         11 . The direct-view LCD recited in  claim 8  wherein where said LCD includes two alignment coating materials, and said coating materials, said gap and said CLC, when in the focal conic state, cooperate to act as a quarter wavelength retarder.  
     
     
         12 . The direct-view LCD recited in  claim 6  wherein said CLC further includes said alignment coating material comprising a polyimide and said gap is about 2 microns.  
     
     
         13 . The direct-view LCD recited in  claim 1  wherein said characteristic wavelength of said CLC is in the ultraviolet spectrum.  
     
     
         14 . The direct-view LCD recited in  claim 13  wherein said characteristic wavelength of said CLC is less than about 380 nm.  
     
     
         15 . The direct-view LCD recited in  claim 13  wherein said characteristic wavelength of said CLC is less than about 450 nm.  
     
     
         16 . The direct-view LCD recited in  claim 13  wherein a surface of said reflector at a boundary between said CLC and said reflector is polished.  
     
     
         17 . The direct-view LCD recited in  claim 1  further comprising a first electrode adjacent an inner surface of said polarizer and a second electrode adjacent an inner surface of said reflector.  
     
     
         18 . The direct-view LCD recited in  claim 1  wherein said polarizer comprises a first circular polarizer.  
     
     
         19 . The direct-view LCD recited in  claim 18  wherein said reflector comprises a transflective mirror and said direct view LCD further comprises a second circular polarizer located posterior to said transflective mirror said second circular polarizer having a polarity different from said first polarizer, and a light source located posterior to said second circular polarizer.  
     
     
         20 . The direct-view LCD recited in  claim 18  further comprises a mirror located posterior to said light source.  
     
     
         21 . The direct-view LCD recited in  claim 1  wherein said reflector has a colored surface.  
     
     
         22 . A method of fabricating a direct-view LCD comprising the steps of: 
 positioning a polarizer;    positioning a reflector thereby forming a gap between said polarizer and reflector; and    packing said gap with a cholesteric liquid crystal (CLC) such that said CLC receives light reflected from said reflector, said CLC having a characteristic wavelength in the non-visible spectrum and capable of exhibiting a planar state or a focal-conic state.    
     
     
         23 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes packing with said CLC comprising a mixture of a nematic liquid crystal and a chiral dopant.  
     
     
         24 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes packing with said mixture comprising about 60 percent to about 90 percent by weight of said nematic liquid crystal and a balance of said mixture comprising said chiral dopant.  
     
     
         25 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes said forming said gap ranging from about 1 micron to about 6 microns.  
     
     
         26 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes said forming said gap ranging from about 2 microns to about 3 microns.  
     
     
         27 . The method as recited in  claim 22  wherein fabricating said direct-view LCD further includes coating said polarizer and said reflector with an alignment coating material.  
     
     
         28 . The method as recited in  claim 27  wherein fabricating said direct-view LCD further includes coating with said alignment coating material comprising a polyimide.  
     
     
         29 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes said packing said CLC having said characteristic wavelength in the infrared spectrum.  
     
     
         30 . The method as recited in  claim 22  wherein said characteristic wavelength of said CLC is greater than about 780 nm.  
     
     
         31 . The method as recited in  claim 22  wherein said characteristic wavelength of said CLC is greater than about 700 nm.  
     
     
         32 . The method as recited in  claim 29  wherein fabricating said direct-view LCD further includes coating said polarizer and said reflector with an alignment coating material, and said coating materials, said gap and said CLC, when in the focal conic state, cooperate to act as a quarter wavelength retarder.  
     
     
         33 . The method as recited in  claim 27  wherein fabricating said direct-view LCD further includes said alignment coating material comprising a polyimide and said gap is about 2 microns.  
     
     
         34 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes said packing said CLC having said characteristic wavelength in the ultraviolet spectrum.  
     
     
         35 . The method as recited in  claim 34  wherein said characteristic wavelength of said CLC is less than about 380 nm.  
     
     
         36 . The method as recited in  claim 34  wherein said characteristic wavelength of said CLC is less than about 450 nm.  
     
     
         37 . The method as recited in  claim 34  wherein fabricating said direct-view LCD further includes polishing a surface of said reflector, said surface at a boundary between said CLC and said reflector.  
     
     
         38 . The method as recited in  claim 22  wherein fabricating said direct-view LCD further includes positioning a first electrode adjacent an inner surface of said polarizer and positioning a second electrode adjacent an inner surface of said reflector.  
     
     
         39 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes positioning said polarizer comprising a first circular polarizer.  
     
     
         40 . The method as recited in  claim 39  wherein fabricating said direct-view LCD includes positioning said reflector comprising a transflective mirror, and said fabricating further comprises positioning a second circular polarizer posterior to said transflective mirror said second circular polarizer having a polarity different from said first polarizer, and positioning a light source posterior to said second circular polarizer.  
     
     
         41 . The method as recited in claim  40  wherein fabricating said direct-view LCD includes positioning a mirror posterior to said light source.  
     
     
         42 . The method as recited in  claim 22  wherein fabricating said direct-view LCD includes positioning a reflector with a colored surface.