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US 5,374,374 AGranted
Supertwist liquid-crystal display
AssigneeMerck Patent GmbH
InventorsGeorg Weber, Herbert Plach, Volker Reiffenrath, Hiroki Yoshitake, Hiroshi Numata
Life of this patent
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Abstract
Supertwist liquid-crystal displays having excellent properties are obtained using a nematic liquid-crystal mixture based on component A which contains one or more compounds of the formula IIa or IIb: ##STR1## one or more compounds of the formulae IIc to IIe: ##STR2## and one or more compounds of the formulae IIf to ##STR3## in which R, L.sup.1 and L.sup.2 and X are as defined herein.
Claims27
A supertwist liquid-crystal display comprising
- two 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 said cell;
- electrode layers with superposed alignment layers on the insides of said outer plates;
- a pitch angle between the longitudinal axes of the molecules at the surface of said outer plates and said outer plates of about 1 degree-30 degrees;
- and
- a twist angle of the liquid-crystal mixture in the cell from alignment layer to alignment layer with a value of 100.degree.-600.degree.;
- wherein said nematic liquid-crystal mixture:
- (a) is based on component A, which contains
- (a1) one or more compounds of formula IIa and one or more compounds of formula IIc:
- ##STR49## wherein R is n-alkyl, n-alkoxy or n-alkenyl having up to 9 carbon atoms, and
- L.sup.1 and L.sup.2 are each H or F;
- and
- (a2) 0-50% by weight of one or more cyano compounds of formulae C1-C4:
- ##STR50## wherein R is n-alkyl, n-alkoxy or n-alkenyl having up to 9 carbon atoms;
- and
- (b) contains 0-40% by weight of a liquid-crystalline component B, which comprises one or more compounds having a dielectric anisotropy of from -1.5 to +1.5 at 20.degree. C. of formula I ##STR51## wherein R.sup.1 and R.sup.2 are each, independently of one another, n-alkyl, n-alkoxy, n-oxaalkyl, .omega.-fluoroalkyl, n-alkenyl or n-alkenyloxy having up to 9 carbon atoms,
- A.sup.1, A.sup.2 and A.sup.3 are each, indecently of one another, 1,4-phenylene, 2- or 3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene or 1,4-cryclohexenylene,
- Z.sup.1 and Z.sup.2 are each, independently of one another, --CH.sub.2 CH.sub.2 --, --C.tbd.C- or a single bond, and
- m is 0, 1 or 2;
- (c) contains 0-20% by weight of a liquid-crystalline component C which comprises one o more compounds having a dielectric anisotropy of below -1.5 and 20.degree. C.;
- and
- (d) contains an optically active component D in an amount that the ratio between the layer thickness and natural pitch of the chiral nematic liquid-crystal mixture is 0.2-1.7;
- and
- wherein said nematic liquid-crystal has a nematic phase range of at least 60.degree. C., viscosity of not more than 35 mPa.s at 20.degree. C. and a dielectric anisotropy of at least +1 at 20.degree. C.
21 more elements
A liquid-crystal mixture comprising:
- (a) component A, which contains
- (a1) one or more compounds of formula IIc:
- ##STR52## wherein R is n-alkyl, n-alkoxy or n-alkenyl having up to 9 carbon atoms, and
- L.sup.1 and L.sup.2 are each H or F;
- and
- (a2) 0-50% by weight of one or more cyano compounds of formulae C1-C4:
- ##STR53## wherein R is n-alkyl, n-alkoxy or n-alkenyl having up to 9 carbon atoms;
- and
- (b) contains 0-40% by weight of a liquid-crystalline component B, which comprises one or more compounds having a dielectric anisotropy of from -1.5 to +1.5 at 20.degree. C., of formula I ##STR54## wherein R.sup.1 and R.sup.2 are each, independently of one another, n-alkyl, n-alkoxy, n-oxaalkyl, .omega.-fluoroalkyl, n-alkenyl or n-alkenyloxy having up to 9 carbon atoms,
- A.sup.1, A.sup.2 and A.sup.3 are each, independently of one another, 1,4-phenylene, 2- or 3-fluoro-l,4-phenylene, trans-1,4-cyclohexylene or 1,4-cyclohexenylene, hexenylene,
- Z.sup.1 and Z.sup.2 are each, independently of one another, --CH.sub.2 CH.sub.2 --, --C.tbd.C-- or a single bond, and
- m is 0, 1 or 2;
- (c) contains 0-20% by weight of a liquid-crystalline component C which comprises one or more compounds having a dielectric anisotropy of below -1.5 at 20.degree. C.;
- and
- (d) contains an optically active component D in such an amount that the ratio between the layer thickness and natural pitch of the chiral nematic liquid-crystal mixture is 0.2--1.7;
- and
- wherein said nematic liquid-crystal has a nematic phase range of at least 60.degree. C., viscosity of not more than 35 mPa.s at 20.degree. C. and a dielectric anisotropy of at least +1 at 20.degree. C.
14 more elements
Dependencies are inferred from the claim text.