Patent ID: 6054193
Filing Date: 2000-04-25
Classification: C09K

Abstract:
A supertwist liquid-crystal display havingtwo plane-parallel outer plates which, together with a frame, form a cell,a nematic liquid-crystal mixture of positive dielectric anisotropy which is present in the cell,electrode layers with superposed alignment layers on the insides of the outer plates,a pitch angle between a longitudinal axis of the molecules at the surface of the outer plates and the outer plates of form about 1 degree to 30 degrees, anda twist angle of a liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of between 100 and 600.degree. C.,a nematic liquid-crystal mixture comprisinga) 10-65% by weight of a liquid-crystalline component A consisting of one or more compounds having a dielectric anisotropy of greater than +1.5;b) 20-90% 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) 5-35% by weight of a liquid-crystalline component T consisting of one or more compounds containing a tolan-4,4'-diyl unit, andd) an optically active component C in such an amount that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the chiral nematic liquid-crystal mixture is from about 0.2 to 1.3,wherein component T is at least one compound of the formula I: ##STR87## in which R.sup.1 is alkyl, alkoxy, alkenyl or alkenyloxy having 1 to 12 carbon atoms,R.sup.2 is alkyl or alkoxy having 1 to 8 carbon atoms,Z is --COO--, --CH.sub.2 CH.sub.2 -- or a single bond,one of the radicals L.sup.1 and L.sup.2 is Fand the other is H,and the liquid-crystal mixture additionally contains at least one compound of the formula I.sup.* : ##STR88## in which Alkenyl.sup.* is an alkenyl radical having up to 7 carbon atoms,L.sup.* is H or F, andR.sup.* is F or an alkyl group having 1 to 12 carbon atoms which is unsubstituted, monosubstituted by CF.sub.3 or at least monosubstituted by F, where, in addition, 1 or 2 non-adjacent CH.sub.2 groups may be replaced by --O--, --CH.dbd.CH--, --CO--, --OCO-- or --COO--.