Patent ID: 6440506
Filing Date: 2002-08-27
Classification: C09K

Abstract:
Supertwist liquid-crystal display comprisingtwo plane-parallel outer plates which, together with a frame, form a cell, a 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 which address each pixel by orthogonal row wave forms, pre-tilt angle between the longitudinal axis of the molecules at the surface of the outer plates and the outer plates of from about 1 degree to 30 degrees, and a twist angle of the liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of between 22.5 and 600Â°, wherein the liquid-crystal mixture comprises a) 30-90% by weight of a liquid-crystalline component A, comprising one or more compounds having a dielectric anisotropy of more than +1.5; b) 10-45% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy from âˆ’1.5 to +1.5; c) 0-10% by weight of a liquid-crystalline component D, comprising one or more compounds having a dielectric anisotropy of less than âˆ’1.5, and d) 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 liquid-crystal mixture is from about 0.2 to 1.3, characterized in that the liquid crystal mixture comprises at least one compound of component A having a 3,4,5-trifluorophenyl group and at least one compound of formula I whereinR3 is an alkenyl group with 2 to 7 C atoms, R4 is an optionally fluorinated alkyl, alkoxy, alkenyl or alkenyloxy group with 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups can be replaced by â€”Oâ€”, â€”CH&boxH;CHâ€”, â€”COâ€”, â€”OCOâ€” or â€”COOâ€” in such a manner that O atoms are not directly adjacent to one another, or, in case m=1, R4 can also be Qâ€”Y, Q is CF2, OCF2, CFH, OCHF or a single bond, Y is F is Cl, L1 and L2 are each independently H or F, and m is 0 or 1.