Patent ID: 6555186
Filing Date: 2003-04-29
Classification: C09K

Abstract:
A TN or STN liquid-crystal display comprising:two outer plates, which, together with a frame, form a cell, a nematic liquid-crystal mixture of positive dielectric anisotropy located in the cell, electrode layers with alignment layers on the insides of the outer plates, a tilt angle between the longitudinal axis of the molecules at the surface of the outer plates and the outer plates of from 0 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 22.5Â° and 600Â°, the nematic liquid-crystal mixture comprising: a) 15-80% by weight of a liquid-crystalline component A consisting of one or more compounds having a dielectric anisotropy of greater than +1.5; b) 20-85% by weight of a liquid-crystalline component B consisting of one or more compounds having a dielectric anisotropy of from âˆ’1.5 to +1.5; c) 0-20% by weight of a liquid-crystalline component D consisting of one or more compounds having a dielectric anisotropy of below âˆ’1.5, and d) optionally, an optically active component C in such an amount that the ratio between the layer thickness, separation of the outer plates, and the natural pitch of the chiral nematic liquid-crystal mixture is from about 0.2 to 1.3, â€ƒwherein the liquid-crystal mixture comprises at least one compound of the formula I in which R1 is an alkyl or alkenyl radical having 1 to 12 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or monosubstituted to per halo-substituted by halogen, and in which, one or two CH2 groups are optionally replaced by â€”Oâ€”, â€”Sâ€”, â€ƒâ€”COâ€”, â€”COâ€”Oâ€”, â€”Oâ€”COâ€” or â€”Oâ€”COâ€”Oâ€” in such a way that O atoms are not linked directly to one another, R2 has one of the meanings indicated for R1 or is X, X is F, Cl, CN, OCN, NCS, SCN or a halogenated alkyl, alkenyl, alkoxy or alkenyloxy radical having 1 to 6 carbon atoms, L1 and L2 are each, independently of one another, H or F, A is trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene or 1,3-dioxane-2,5-diyl, and u is 0 or 1, and wherein the nematic liquid crystal mixture further comprises at least one alkenyl compound of the formula II in which R3 is an alkenyl group having 2 to 7 carbon atoms, R4 has one of the meanings indicated for R1 is or Qâ€”Y, Q is CF2, OCF2, CFH, OCFH or a single bond, Y is F or Cl, L1 and L2 are each, independently of one another, H or F, and m is 0 or 1.