Curved, arcuately-bonded liquid crystal cell and method of making

Abstract

Curved, arcuately-bonded liquid-crystal cells that include substrates held together by an edge adhesive cured after the substrates were bent into a congruently curved configuration; methods of making such cells; and, switchable shutters and automatic darkening filters that include such cells.

What is claimed is: 
     
         1 . A curved, arcuately-bonded liquid-crystal cell comprising:
 first and second optically-transparent, flexible, multilayer glass-based substrates that are congruently curved and that define a gap between an inwardmost major surface of the first substrate and an inwardmost major surface of the second substrate, and,   a curved layer of liquid-crystal material disposed in the gap between the first and second substrates and in contact with the inwardmost major surface of the first substrate and the inwardmost major surface of the second substrate;
 wherein the first and second substrates are held together by an edge adhesive disposed within the gap between the first and second substrates and cured after the first and second substrates were bent into their congruently curved configuration, so that the liquid-crystal cell is a curved, arcuately-bonded liquid-crystal cell. 
   
     
     
         2 . The curved, arcuately-bonded liquid-crystal cell of  claim 1  wherein the first and second substrates each comprise a transparent conductive layer disposed on an at least a majority of an inward major surface of a flexible glass sheet of the substrate. 
     
     
         3 . The curved, arcuately-bonded liquid-crystal cell of  claim 2  wherein the first and second substrates each comprise an alignment layer disposed on at least a majority of an inward major surface of the transparent conductive layer of the substrate, each of which alignment layers comprises an inward major surface that provides the inwardmost major surface of the substrate and that is in contact with a outward major surface of the liquid-crystal material. 
     
     
         4 . The curved, arcuately-bonded liquid-crystal cell of  claim 3  wherein the edge adhesive is present as a continuous strip that extends along an entirety of a picture-frame border of the substrates and that completely circumferentially bounds an interior area of the gap that contains the liquid-crystal material 
     
     
         5 . The curved, arcuately-bonded liquid-crystal cell of  claim 4  wherein at least at some locations along the strip of edge adhesive, the edge adhesive is in contact with, and is bonded to, the inward major surface of the first alignment layer and the inward major surface of the second alignment layer. 
     
     
         6 . The curved, arcuately-bonded liquid-crystal cell of  claim 3  wherein the edge adhesive is a coalesced adhesive that was deposited on an inwardmost major surface of the first substrate or of the second substrate, in the form of droplets that coalesced into a continuous bead to provide the continuous adhesive strip after curing of the adhesive. 
     
     
         7 . The curved, arcuately-bonded liquid-crystal cell of  claim 1  wherein the curved, arcuately-bonded liquid-crystal cell comprises a multiplicity of discrete spacers randomly distributed throughout a length and breadth of the curved layer of liquid-crystal material. 
     
     
         8 . A curved switchable filter comprising:
 a curved first polarization filter having a first polarization direction;   a curved second polarization filter having a second polarization direction, which may be the same or different from the first polarization direction; and   a curved, arcuately-bonded liquid-crystal cell of  claim 1  sandwiched between the first and second polarization filters,
 wherein the curved switchable filter is capable of being switched between at least a dark state and a light state. 
   
     
     
         9 . A curved automatic darkening filter comprising:
 at least one curved switchable shutter of  claim 8 , and   a shutter control system that is controllably connected to the switchable shutter.   
     
     
         10 . A vision-protective headgear comprising:
 a curved automatic darkening filter of  claim 9  mounted in an optically transmissive window of the vision-protective headgear.   
     
     
         11 . A method of making a curved, arcuately-bonded liquid-crystal cell, the method comprising:
 depositing an edge adhesive along a picture-frame border of an inwardmost major surface of a first optically-transparent, flexible, multilayer glass-based substrate;   depositing a liquid-crystal material onto an interior area of the inwardmost major surface of the first optically-transparent, flexible, multilayer glass-based substrate or onto an interior area of an inwardmost major surface of a second optically-transparent, flexible, multilayer glass-based substrate; then,   bringing the first and second substrates together so that the edge adhesive is in contact with the inwardmost major surface of the first substrate and with the inwardmost major surface of the second substrate; then,   simultaneously bending the first substrate and the second substrate into a congruently curved configuration; then,   curing the edge adhesive while the first substrate and the second substrate are held in the congruently curved configuration, to produce a curved, arcuately-bonded liquid-crystal cell.   
     
     
         12 . The method of  claim 11  wherein the first substrate and the second substrate are held in the congruently curved configuration by a temporary holding fixture, and wherein after the edge adhesive is cured the curved, arcuately-bonded liquid-crystal cell is released from the temporary holding fixture. 
     
     
         13 . The method of  claim 11  wherein after the first and second substrates are brought together the interior area containing the liquid-crystal material is completely circumferentially bounded by the edge adhesive. 
     
     
         14 . The method of  claim 11  wherein the edge adhesive is deposited along the picture-frame border of the inwardmost major surface of the first substrate in the form of droplets, which droplets, after being deposited on the major surface, coalesce with each other to form a continuous bead that provides a continuous adhesive strip after curing the adhesive. 
     
     
         15 . The method of  claim 11  wherein the first and second substrates are simultaneously bent into the congruently curved configuration by being urged against a curved surface of a mandrel. 
     
     
         16 . The method of  claim 11  wherein:
 the depositing of the edge adhesive onto the inwardmost major surface of the first substrate is done with the first substrate held in a flat configuration; and, 
 the depositing of the liquid-crystal material onto the inwardmost major surface of the first substrate or of the second substrate is done with the substrate on which the liquid-crystal material is deposited held in a flat configuration. 
 
     
     
         17 . The method of  claim 11  wherein the bringing of the first and second substrates together so that the edge adhesive is in contact with the inwardmost major surface of the first substrate and with the inwardmost major surface of the second substrate, is done by the following steps:
 placing the first and second substrates into an evacuable chamber; 
 holding the first substrate in a flat configuration by a first fixture within the evacuable chamber; 
 holding the second substrate in a flat configuration by a second fixture within the evacuable chamber; 
 closing the evacuable chamber and evacuating the gaseous contents of the evacuable chamber; 
 then, while the evacuable chamber is maintained in an evacuated condition and while the first and second substrates are each held in a flat configuration,
 bringing the first and second fixtures toward each other to bring the first and second substrates together so that the edge adhesive is in contact with the inwardmost major surface of the first substrate and with the inwardmost major surface of the second substrate. 
 
 
     
     
         18 . The method of  claim 11  wherein the method further comprises sandwiching the curved, arcuately-bonded liquid-crystal cell between a curved first polarization filter having a first polarization direction and a curved second polarization filter having a second polarization direction, which may be the same or different from the first polarization direction, to produce a curved switchable filter capable of being switched between at least a dark state and a light state. 
     
     
         19 . The method of  claim 18  further comprising the step of connecting a shutter control system to the curved switchable filter to form an automatic darkening filter. 
     
     
         20 . The method of  claim 19  further comprising the step of installing the automatic darkening filter into a vision-protective headgear.