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US 5,997,767 AGranted
STN liquid-crystal display
AssigneeMerck Patent GmbH
InventorsHarald Hirschmann, Clarissa Weller, Volker Reiffenrath
Life of this patent
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Abstract
The invention relates to supertwist liquid-crystal displays (SLCDs) having very short response times and good steepnesses and angle dependences, and to the nematic liquid-crystal mixtures according to the invention used therein, which are distinguished by the fact that they comprise at least one compound of the formula IA and at least one compound of the formula IB ##STR1## in which R, R.sup.3, R.sup.4 and C are as defined herein.
Claims12
A supertwist liquid-crystal display comprising two 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 alignment layers on the insides of the outer plates,
- a pretilt 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 22.5.degree. and 600.degree.,
- wherein the nematic liquid-crystal mixture comprises
- a) 20-90% by weight of a liquid-crystalline component A consisting of one or more compounds having a dielectric anisotropy of greater than +1.5;
- b) 10-80% 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 of below -1.5, and
- d) 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,
- wherein component A comprises at least one compound of the formula IA ##STR72## in which R is an alkyl, alkoxy or alkenyl group having 1 to 12 carbon atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups are optionally replaced by --O--, --CH.dbd.CH--, --CO--, --OCO-- or --COO--in such a way that O atoms are not linked directly to one another,
- and component B comprises at least one compound of the formula IB ##STR73## in which R.sup.3 is an alkenyl group having 2 to 7 carbon atoms,
- R.sup.4 independently has the meaning of R or R.sup.3 and
- c is 0 or 1.
10 more elements
A liquid-crystal mixture which comprises
- a) 20-90% by weight of a liquid-crystalline component A consisting of one or more compounds having a dielectric anisotropy of greater than +1.5;
- b) 10-80% 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 of below -1.5, and
- d) 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,
- wherein component A comprises at least one compound of the formula IA ##STR85## in which R is an alkyl, alkoxy or alkenyl group having 1 to 12 carbon atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups are optionally replaced by --O--, --CH.dbd.CH--, --CO--, --OCO-- or --COO--in such a way that O atoms are not linked directly to one another,
- and component B comprises at least one compound of the formula IB ##STR86## in which R.sup.3 is an alkenyl group having 2 to 7 carbon atoms,
- R.sup.4 independently has the meaning of R or R.sup.3 and c is 0 or 1.
4 more elements
Dependencies are inferred from the claim text.