Manufacturing method of liquid crystal display element and manufacturing device for use with the same

Abstract

A liquid crystal cell is moved into a vacuum oven in a “vacuum oven loading” step. The heater power source of the vacuum oven is turned off and the chamber in the vacuum oven is evacuated to a degree of vacuum (vacuum condition) of about 100 Pa in an “evacuation starting” step. Then, the liquid crystal cell is slowly cooled to, for example, 40° C. while maintaining that degree of vacuum. Subsequently, nitrogen gas is substituted for the contents of the liquid crystal cell in a “nitrogen gas substitution” step, by introducing nitrogen gas to the chamber in the slow cooled vacuum oven and thereby restoring normal pressure. Thereafter, liquid crystal is charged to the liquid crystal cell in an “injection” step, followed by a “sealing” step whereby an injection opening is sealed with a sealant, and ultraviolet light from which 330 nm or shorter wavelength light is projected to cure the sealant. A liquid crystal display element in accordance with the present invention is thus fabricated.

What is claimed is:  
     
         1 . A manufacturing method of a liquid crystal display element, comprising the sequential steps of: 
 (1) evacuating a liquid crystal cell by means of depressurization;    (2) substituting an inert gas for contents of the liquid crystal cell; and    (3) charging liquid crystal to the liquid crystal cell.    
     
     
         2 . The manufacturing method of a liquid crystal display element as defined in  claim 1 , 
 wherein: 
 an interior of the liquid crystal cell is heated simultaneously with the evacuation by means of depressurization.  
   
     
     
         3 . The manufacturing method of a liquid crystal display element as defined in  claim 2 , 
 wherein: 
 an interior of the liquid crystal cell is slowly cooled while evacuating by means of depressurization; and  
 thereafter, an inert gas is substituted for contents of the liquid crystal cell.  
   
     
     
         4 . The manufacturing method of a liquid crystal display element as defined in  claim 1 , 
 wherein: 
 the liquid crystal cell is constituted by a pair of plastic substrates.  
   
     
     
         5 . The manufacturing method of a liquid crystal display element as defined in  claim 1 , 
 wherein: 
 the liquid crystal cell is depressurized to about 100 Pa.  
   
     
     
         6 . The manufacturing method of a liquid crystal display element as defined in  claim 1 , 
 wherein: 
 the inert gas is any one of nitrogen gas, helium gas, argon gas, and neon gas.  
   
     
     
         7 . The manufacturing method of a liquid crystal display element as defined in  claim 2 , 
 wherein: 
 the interior of the liquid crystal cell is heated at a temperature not lower than 100° C. and not higher than 150° C.  
   
     
     
         8 . The manufacturing method of a liquid crystal display element as defined in  claim 4 , 
 wherein: 
 the plastic substrate is made of at least one compound selected from the group consisting of polycarbonate, a crosslinking heat resistant acrylic resin, polyether sulfone, an epoxy resin, or cyclic polyolefin.  
   
     
     
         9 . A manufacturing method of a liquid crystal display element, comprising the sequential steps of: 
 (1) sealing, with a UV-curing sealant, a liquid crystal cell in which liquid crystal is charged;    (2) curing the sealant by projecting to the sealant ultraviolet light in such a wavelength region where the concentration extinction coefficient k of the liquid crystal is stable near 0.    
     
     
         10 . The manufacturing method of a liquid crystal display element as defined in  claim 9 , 
 wherein: 
 the ultraviolet light is obtained using a filter.  
   
     
     
         11 . The manufacturing method of a liquid crystal display element as defined in  claim 10 , 
 wherein: 
 the filter is made of polyether sulfone.  
   
     
     
         12 . A manufacturing method of a liquid crystal display element, comprising the sequential steps of: 
 (1) sealing, with a UV-curing sealant, a liquid crystal cell in which liquid crystal is charged;    (2) curing the sealant by projecting to the sealant ultraviolet light from which 330 nm or shorter wavelength light is removed.    
     
     
         13 . The manufacturing method of a liquid crystal display element as defined in  claim 12 , 
 wherein: 
 the 330 nm or shorter wavelength light is removed using a filter.  
   
     
     
         14 . The manufacturing method of a liquid crystal display element as defined in  claim 13 , 
 wherein: 
 the filter is made of polyether sulfone.  
   
     
     
         15 . A manufacturing device of a liquid crystal display element, comprising: 
 a depressurization device for depressurizing a liquid crystal cell;    an inert gas substitution device for substituting an inert gas for contents of the liquid crystal cell; and    a liquid crystal charging device for charging liquid crystal in the liquid crystal cell,    the three devices being lined in this order with no intervening members.    
     
     
         16 . The manufacturing device of a liquid crystal display element as defined in  claim 15 , 
 wherein: 
 the depressurization device includes a preliminary evacuation device and a vacuum device which are lined in this order with no intervening members.  
   
     
     
         17 . The manufacturing device of a liquid crystal display element as defined in  claim 16 , 
 wherein: 
 the vacuum device is adapted to depressurize the liquid crystal cell to about 100 Pa.  
   
     
     
         18 . The manufacturing device of a liquid crystal display element as defined in  claim 15 , 
 wherein: 
 the inert gas substitution device includes a pressure adjusting device and a substitution device which are lined in this order with no intervening members.  
   
     
     
         19 . The manufacturing device of a liquid crystal display element as defined in  claim 15 , 
 wherein: 
 the depressurization device includes a preliminary evacuation device and a vacuum device which are lined in this order with no intervening members; and  
 the inert gas substitution device includes a pressure adjusting device and a substitution device which are lined in this order with no intervening members.  
   
     
     
         20 . The manufacturing device of a liquid crystal display element as defined in  claim 15 , further comprising: 
 a heating device for heating the liquid crystal cell lined before the depressurization device with no intervening members.    
     
     
         21 . The manufacturing device of a liquid crystal display element as defined in  claim 20   wherein: 
 the heating device is adapted to heat an interior of the liquid crystal cell at a temperature not lower than 100° C. and not higher than 150° C.  
   
     
     
         22 . The manufacturing device of a liquid crystal display element as defined in  claim 15 , further comprising: 
 a transport means for transporting the liquid crystal cell.    
     
     
         23 . The manufacturing device of a liquid crystal display element as defined in  claim 22   wherein: 
 the transport means is a belt conveyor.