Novel nematic liquid crystal mixtures useful for the production of twisted nematic and supertwisted nematic liquid crystal displays

摘要

Novel nematic liquid crystal mixtures are claimed. A nematic liquid crystal mixture (I) contains at least one compound of formula (1) and at least one compound of formula (2). (1) (2) (3) (4) R<1>,R<2> = 1-5C alkyl or alkenyl, optionally monosubstituted by CN or CF3 or at least monosubstituted by halogen, whereby at least one non-neighbouring CH2 group is optionally replaced by -O-, -S-, -CC- or -OC-O-; Y = F, Cl or 1-6C hydrogenated alkyl, alkenyl or alkoxy; A=formula (3)-(4) An Independent claim is included for a twisted nematic (TN) or supertwisted nematic (STN) liquid crystal dispaly device having two substrate plates that form a cell with an edging, in which a nematic liquid crystal mixture having positive dielectric anisotropy, electrode layers having orientation layers on the inner face of the substrate plates, an initial angle of 0-30 deg between the long axis of the molecule on the substrate plate surface and the substrate plate, a twist angle of the liquid crystal mixture in the cell of 22.5-600 deg , and a liquid crystal mixture comprising (A) 15-75 wt.% of a liquid crystal component of at least one compound having an dielectric anisotropy of greater than ?+1.5, (B) 25-85 wt.% of a liquid crystal component of at least one compound having an dielectric anisotropy of ?-1.5-?+1.5. (C)0-20 wt.% of a liquid crystal component of at least one compound having an dielectric anisotropy of less than ?-1.5 and (D) optionally an optically active component such that the ratio between layer thickness and the natural pitch of the chiral nematic liquid crystal mixture is 0.2-1.3 where (A) comprises compounds of formula (1) and (2).