Liquid crystal cell with compensator layer and process

Abstract

Disclosed is a liquid crystal cell having contiguous to a surface of a constraint thereof one or more compensator layers, each containing a transparent amorphous polymeric birefringent material having an out-of plane birefringence more negative than −0.005. The invention also provides a liquid crystal display and a process for making such a cell.

What is claimed is:  
     
         1 . A liquid crystal cell having contiguous to a surface of a constraint thereof one or more compensator layers, each containing a transparent amorphous polymeric birefringent material having an out-of plane birefringence more negative than −0.005.  
     
     
         2 . The cell of  claim 1  bearing more than one of said polymeric compensator layers.  
     
     
         3 . The cell of  claim 1  comprising compensator layers containing selected polymeric materials having sufficient thickness so that the overall in-plane retardation (Re) of all of the layers of the liquid crystal cell is from +20 to −20 nm and the out-of-plane retardation (Rth) of at least one of the compensator layers is more negative than −20 nm.  
     
     
         4 . The cell of  claim 1  comprising at least two compensator layers.  
     
     
         5 . The cell of  claim 1  wherein the one or more compensator layers have a combined thickness of less than 30 micrometers.  
     
     
         6 . The cell of  claim 5  wherein the one or more compensator layers have a combined thickness of from 0.1 to 20 micrometers.  
     
     
         7 . The cell of  claim 6  wherein the one or more compensator layers have a combined thickness of from 1.0 to 10 micrometers.  
     
     
         8 . The cell of  claim 7  wherein the one or more compensator layers have a combined thickness of from 2 to 8 micrometers.  
     
     
         9 . The cell of  claim 1  wherein the Rth of the one or more compensator layers is −60 nm or more negative.  
     
     
         10 . The cell of  claim 1  wherein the Rth of the one or more compensator layers is from −60 to −600 nm.  
     
     
         11 . The cell of  claim 1  wherein the Rth of the one or more compensator layers is from −150 to −500 nm.  
     
     
         12 . The cell of  claim 1  wherein the one or more compensator layers comprise a polymer containing in the backbone a non-visible chromophore group and having a Tg above 180° C.  
     
     
         13 . The cell of  claim 12  wherein the compensator layer comprises a polymer containing in the backbone a carbonyl or an aromatic group.  
     
     
         14 . The cell of  claim 12  wherein the non-visible chromophore group includes a carbonyl, amide, imide, ester, carbonate, phenyl, naphthyl, biphenyl, bisphenol, or thiophene group.  
     
     
         15 . The cell of  claim 12  wherein the compensator layer comprises 
 1)poly(4,4′-hexaflouroisopropylidene-bisphenol) terephthalate-co-isophthalate,  
 2)poly(4,4′-hexahydro-4,7-methanoinden-5-ylidene bisphenol) terephthalate, or  
 3) Poly(4,4′-isopropylidene-2,2′6,6′-tetrachlorobisphenol) terephthalate-co-isophthalate, or copolymers thereof.  
 
     
     
         16 . The cell of  claim 12  wherein the compensator layer comprises a polymer containing in the backbone a non-visible chromopore group that does not contain a chromophore off of the backbone.  
     
     
         17 . The cell of  claim 1  wherein the liquid crystal cell is a vertically aligned or a twisted nematic cell.  
     
     
         18 . The cell of  claim 1  employing in-plane switching.  
     
     
         19 . The cell of  claim 1  wherein the constraints are glass.  
     
     
         20 . The cell of  claim 1  wherein the surface is an exterior surface of the cell constraint.  
     
     
         21 . A liquid crystal display comprising the liquid crystal cell of  claim 1 .  
     
     
         22 . A process for forming a liquid crystal display comprising coating the polymer of  claim 1  in a solvent onto a surface of a constraint of the cell.  
     
     
         23 . The process of  claim 22  wherein the constraint is glass.