Liquid crystal display and method for manufacturing same

Abstract

A liquid crystal display is provided which is capable of reducing the occurrence of defective display due to variations in the initial alignment direction of a liquid crystal alignment control film in a liquid crystal display of an IPS scheme, realizing the stable liquid crystal alignment, providing excellent mass productivity, and having high image quality with a higher contrast ratio. The liquid crystal display has a liquid crystal layer disposed between a pair of substrates, at least one of the substrates being transparent, and an alignment control film formed between the liquid crystal layer and the substrate. At least one of the alignment control films 109 comprises photoreactive polyimide and/or polyamic acid provided with an alignment control ability by irradiation of substantially linearly polarized light.

1 . An IPS type liquid crystal display device comprising:
 A Pair of substrates;   A liquid crystal layer between the pair of substrates; and   A photo alignment control film on one of the substrates;   wherein the photo alignment control film includes a polyamic acid or polyimide that is made from cyclobutanetetracarboxylic acid dianhydride and/or its derivative and aromatic diamine; and   wherein the cyclobutanetetracarboxylic acid dianhydride and/or its derivative contains a compound represented by a formula [1].   
       
         
           
           
               
               
           
         
       
     
     
         2 . The IPS type liquid crystal display device according to  claim 1 , wherein the aromatic diamine compound contains at least one of compounds selected from a group of compounds consisting of ones represented by formulas [2] to [16]: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         where R 1 , R 2 , R 3  and R 4  of the compounds represented by formulas [2] to [16] each independently represent a hydrogen atom, a fluorine atom, an alkyl group or alkoxyl group with a carbon number of 1 to 6, or vinyl group {—(CH 2 ) m —CH═CH 2 , m=0, 1, 2} or a group represented by {—(CH 2 ) n —C≡CH, n=0, 1, 2}, and in the formula [5], X represents a bond group —S—, —CO—, or —NH—. 
       
     
     
         3 . The IPS type liquid crystal display device according to  claim 1 , wherein said alignment control film is polyamic acid or polyimide containing at least 50% of a repeated structure of polyamic acid or polyimide comprising said cyclobutanetetracarboxylic acid dianhydride and/or its derivative and said aromatic diamine. 
     
     
         4 . The IPS type liquid crystal display device according to  claim 1 , wherein the photo alignment film having a glass transition temperature equal to or higher than 250° C. 
     
     
         5 . The IPS type liquid crystal display device according to  claim 1 , wherein the photo film having been subjected to alignment processing by irradiating the film with polarized light having a wavelength in a range of 200 to 400 nm. 
     
     
         6 . The IPS type liquid crystal display device according to  claim 5 , wherein said alignment processing further comprises applying at least one of heating, irradiation of infrared rays, irradiation of far infrared rays, irradiation of electron beams and irradiation of radioactive rays, after a heating for imidization. 
     
     
         7 . The IPS type liquid crystal display device according to  claim 1 , wherein the alignment control film has a thickness of from 1 nm to 100 nm. 
     
     
         8 . The IPS type liquid crystal display device according to  claim 1  further comprising a plurality of pixel electrodes and a common electrode overlapping with the plurality of pixel electrodes. 
     
     
         9 . The IPS type liquid crystal display device according to  claim 1  wherein the cyclobutanetetracarboxylic acid dianhydride and/or its derivative contains a compound represented by a formula [17]. 
       
         
           
           
               
               
           
         
       
     
     
         10 . The IPS type liquid crystal display device according to  claim 1  wherein the aromatic diamine compound contains a compound represented by a formula [18]. 
       
         
           
           
               
               
           
         
       
     
     
         11 . An photo alignment film material for an IPS type liquid crystal display device, adapted to be an alignment control film of a liquid crystal display, comprising a polyamic acid or polyimide that includes cyclobutanetetracarboxylic acid dianhydride and/or its derivative and aromatic diamine; and
 wherein the cyclobutanetetracarboxylic acid dianhydride and/or its derivative contains a compound represented by a formula [1].   
       
         
           
           
               
               
           
         
       
     
     
         12 . The photo alignment film material according to  claim 9 , wherein the aromatic diamine compound contains at least one of compounds selected from a group of compounds consisting of ones represented by formulas [2] to [16]: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         where R 1 , R 2 , R 3  and R 4  of the compounds represented by formulas [2] to [16] each independently represent a hydrogen atom, a fluorine atom, an alkyl group or alkoxyl group with a carbon number of 1 to 6, or vinyl group {—(CH 2 ) m —CH═CH 2 , m=0, 1, 2} or a group represented by {—(CH 2 ) n —C≡CH, n=0, 1, 2}, and in the formula [5], X represents a bond group —S—, —CO—, or —NH—. 
       
     
     
         13 . The photo alignment film material according to  claim 11 , wherein the aromatic diamine compound contains a compound represented by formula [2]: 
       
         
           
           
               
               
           
         
         where R 1 , R 2 , of the compounds represented by formulas [2] independently represent a hydrogen atom, a fluorine atom, an alkyl group or alkoxyl group with a carbon number of 1 to 6, or vinyl group {—(CH 2 ) m —CH═CH 2 , m=0, 1, 2} or a group represented by {—(CH 2 ) n —C≡CH, n=0, 1, 2}. 
       
     
     
         14 . The photo alignment film material according to  claim 11 , wherein said alignment control film is polyamic acid or polyimide containing at least 50% of a repeated structure of polyamic acid or polyimide comprising said cyclobutanetetracarboxylic acid dianhydride and/or its derivative and said aromatic diamine. 
     
     
         15 . The photo alignment film material according to  claim 11 , wherein the photo film having been subjected to alignment processing by irradiating the film with polarized light having a wavelength in a range of 200 to 400 nm. 
     
     
         16 . The photo alignment film material according to  claim 15 , wherein said alignment processing further comprises applying at least one of heating, irradiation of infrared rays, irradiation of far infrared rays, irradiation of electron beams and irradiation of radioactive rays, after a heating for imidization. 
     
     
         17 . The photo alignment film material according to  claim 11  wherein the cyclobutanetetracarboxylic acid dianhydride and/or its derivative contains a compound represented by a formula [17]. 
       
         
           
           
               
               
           
         
       
     
     
         18 . The photo alignment film material according to  claim 11  wherein the aromatic diamine compound contains a compound represented by a formula [18].