Patent ID: 6080451
Filing Date: 2000-06-27
Classification: C09K

Abstract:
Supertwisted liquid crystal display havingtwo carrier plates which, together with a frame, form a cell,a nematic liquid crystal mixture of positive dielectric anisotropy present in the cell,electrode layers having orientation layers on the insides of the carrier plates,a tilt angle of 1 degree to 30 degrees between the longitudinal axis of the molecules on the surface of the carrier plates and the carrier plates,a twist angle of the liquid crystal mixture in the cell from orientation layer to orientation layer of between 100.degree. and 600.degree. in magnitude, anda nematic liquid crystal mixture consisting ofa) 20-95% by weight of a liquid-crystalline component A consisting of one or more compounds having a dielectric anisotropy of more than +1.5,b) 5-80% by weight of a liquid-crystalline component B consisting of one or more compounds having a dielectric anisotropy of between -1.5 and +1.5,c) 0-20% by weight of a liquid-crystalline component D consisting of one or more compounds having a dielectric anisotropy below -1.5, andd) an optically active component C in such an amount that the ratio between the layer thickness (spacing of the carrier plates) and the natural pitch of the chiral nematic liquid crystal mixture is about 0.2 to 1.3,characterized in that the liquid crystal mixture comprises at least one compound of the formula IA ##STR81## in which R.sup.a is alkyl, alkoxy, alkenyl or alkenyloxy having 1 to 12 carbon atoms,R.sup.b is alkyl or alkoxy having 1 to 5 carbon atoms,Z is --COO--, --CH.sub.2 CH.sub.2 -- or a single bond, andL.sup.a, L.sup.b, L.sup.c, L.sup.d, L.sup.e, L.sup.f, L.sup.g and L.sup.h are each, independently of one another, H or F,with the provisos that(a) at least one of the radicals L.sup.a, L.sup.b, L.sup.c, L.sup.d, L.sup.e, L.sup.f, L.sup.g and L.sup.h is F and(b) the 1,4-phenylene rings carry at most 2 fluorine atoms per ring,and component B comprises at least one compound of the formula IB ##STR82## in which R.sup.3 is an alkenyl group having 2 to 7 carbon atoms,R.sup.4 has the meaning of R.sup.a, andc is 0 or 1.