Reverse transmittance 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 transmissive mode displays, and methods of fabrication. In accordance with the principles disclosed, a transmitance mode direct-view LCD includes a first linear polarizer, a second linear polarizer, an internal light source and a cholesteric liquid crystal (CLC) located between the first and second linear polarizers and having a characteristic wavelength to reflect in a non-visible region of light. 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.

What is claimed is:  
     
         1 . A direct-view liquid crystal display (LCD), comprising: 
 a first linear polarizer;    a second linear polarizer having a polarity different from said first linear polarizer, wherein at least one of said first and second linear polarizers does not form a portion of a circular polarizer;    a cholesteric liquid crystal (CLC) located in a gap between said first and second linear polarizers, said CLC having a characteristic wavelength in a non-visible region and capable of exhibiting a planar state or a focal-conic state; and    a light source situated behind said second linear polarizer.    
     
     
         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 microns 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 an infrared region.  
     
     
         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 1  wherein said characteristic wavelength of said CLC is in an ultraviolet region.  
     
     
         12 . The direct-view LCD recited in  claim 11  wherein said characteristic wavelength of said CLC is less than about 380 nm.  
     
     
         13 . The direct-view LCD recited in  claim 11  wherein said characteristic wavelength of said CLC is less than about 450 nm.  
     
     
         14 . The direct-view LCD recited in  claim 11  wherein a surface of said reflector at a boundary between said CLC and said second linear polarizer is polished.  
     
     
         15 . The direct-view LCD recited in  claim 1  further comprising a first electrode beside an inner surface of said first linear polarizer and a second electrode beside an inner surface of said second linear polarizer.  
     
     
         16 . The direct-view LCD recited in  claim 1  wherein said second linear polarizer has an opposite polarity as said first linear polarizer.  
     
     
         17 . The direct-view LCD recited in  claim 1  further including one or more colored filters located between said light source and said first linear polarizer.  
     
     
         18 . A method of fabricating a direct-view LCD comprising the steps of: 
 placing a first linear polarizer;    placing a second linear polarizer thereby forming a gap between said first linear polarizer and said second polarizer, said second linear polarizer having a polarity different from said first linear polarizer, wherein at least one of said first and second linear polarizers does not form a portion of a circular polarizer;    filling said gap with a cholesteric liquid crystal (CLC) , said CLC having a characteristic wavelength in a non-visible region and capable of exhibiting a planar state or a focal-conic state; and    placing a light source behind said second linear polarizer.    
     
     
         19 . The method as recited in  claim 18  wherein fabricating said direct-view LCD includes said filling with said CLC comprising a mixture of a nematic liquid crystal and a chiral dopant.  
     
     
         20 . The method as recited in  claim 18  wherein fabricating said direct-view LCD includes said filling 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.  
     
     
         21 . The method as recited in  claim 18  wherein fabricating said direct-view LCD includes said forming said gap ranging from about 1 microns to about 6 microns.  
     
     
         22 . The method as recited in  claim 18  wherein fabricating said direct-view LCD includes said forming said gap ranging from about 2 microns to about 3 microns.  
     
     
         23 . The method as recited in  claim 18  wherein fabricating said direct-view LCD further includes coating said polarizer and said reflector with an alignment coating material.  
     
     
         24 . The method as recited in  claim 23  wherein fabricating said direct-view LCD further includes coating with said alignment coating material comprising a polyimide.  
     
     
         25 . The method as recited in  claim 18  wherein fabricating said direct-view LCD includes said filling said CLC having said characteristic wavelength in an infrared region.  
     
     
         26 . The method as recited in  claim 25  wherein said characteristic wavelength of said CLC is greater than about 780 nm.  
     
     
         27 . The method as recited in  claim 25  wherein said characteristic wavelength of said CLC is greater than about 700 nm.  
     
     
         28 . The method as recited in  claim 18  wherein fabricating said direct-view LCD includes said filling said CLC having said characteristic wavelength an ultraviolet region.  
     
     
         29 . The method as recited in  claim 28  wherein said characteristic wavelength of said CLC is less than about 380 nm.  
     
     
         30 . The method as recited in  claim 28  wherein said characteristic wavelength of said CLC is less than about 450 nm.  
     
     
         31 . The method as recited in  claim 28  wherein fabricating said direct-view LCD includes polishing a surface of said second linear polarizer, said surface at a boundary between said CLC and said second linear polarizer.  
     
     
         32 . The method as recited in  claim 18  wherein fabricating said direct-view LCD includes placing a first electrode beside an inner surface of said first linear polarizer and placing a second electrode beside an inner surface of said second linear polarizer.  
     
     
         33 . The method as recited in  claim 18  wherein said polarity of said second linear polarizer is opposite a polarity of said first linear polarizer.  
     
     
         34 . The method as recited in  claim 18  wherein fabricating said direct-view LCD further includes locating a colored filter between said light source and said first linear polarizer.