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US 5,308,538 AGranted
Supertwist liquid-crystal display
AssigneeMerck Patent GmbH
InventorsGeorg Weber, Joachim Ruger, Klaus-Peter Stahl, Martina Schmidt, Detlef Pauluth, Michael Romer
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## on or more compounds of the formulae IIc to IIe: ##STR2## and one or more compounds of the formula IIf to IIh: and one or more compounds of the formula IIf to IIh: ##STR3## wherein R, R.sup.1, R.sup.2, L, Y, X and n are as defined herein.
Claims28
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 present in said cell;
- electrode layers with superposed alignment layers on the insides of said outer plates;
- a pitch angle between the longitudinal axis of the molecules at the surface of said outer plates and the outer plates of 1-30 degrees;
- and
- a twist angle of said liquid-crystal mixture in said 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 one or more compounds of the formula IIa:
- ##STR54## one or more compounds of the formulae IIc to IIe:
- ##STR55## and one or more compounds of the formulae IIf to IIh:
- ##STR56## in which R.sup.1 and R.sup.2 are each, independently, alkyl wherein the total number of carbon atoms in R.sup.1 and R.sup.2 together is 4-7,
- R is, in each case, independently, n-alkyl, n-alkoxy or n-alkenyl having up to 9 carbon atoms, ##STR57## are each independently ##STR58## Y and L are each independently H or F, X is F, Cl, --CF.sub.3, --CHF.sub.2, --OCF.sub.3, --OCHF.sub.2, --OCF.sub.2 CF.sub.2 H or --OC.sub.2 F.sub.5, and
- n is 0 or 1;
- b) contains 0-40% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy of -1.5 to +1.5 at 20.degree. C., of formula I ##STR59## wherein R.sup.1 and R.sup.2 are each independently n-alkyl, n-alkoxy, n-oxaalkyl, straight-chain .omega.-fluoroalkyl or n-alkenyl having up to 9 carbon atoms,
- A.sup.1, A.sup.2 and A.sup.3 are each independently 1,4-phenylene, 2- or 3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene or 1,4-cyclohexenylene,
- 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 and 2;
- c) contains 0-5% by weight of a liquid-crystalline component C, comprising 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 the natural pitch of the chiral nematic liquid-crystal mixture is 0.2 to 1.3;
- and
- said nematic liquid-crystal mixture has a nematic phase range of at least 60.degree. C., a viscosity of not more than 35 mPa.s at 20.degree. C. and a dielectric anisotropy of at least +1 at 20.degree. C.
19 more elements
A chiral nematic liquid-crystal mixture comprising at least two components wherein said nematic liquid-crystal mixture
- a) is based on component A, which contains one or more compounds of the formula IIa:
- ##STR70## one or more compounds of the formulae IIc to IIe:
- ##STR71## and one or more compounds of the formulae IIf to IIh:
- ##STR72## in which R.sup.1 and R.sup.2 are each, independently, alkyl wherein the total number of carbon atoms in R.sup.1 and R.sup.2 together is 4-7,
- R is, in each case, independently, n-alkyl, n-alkoxy or n-alkenyl having up to 9 carbon atoms, ##STR73## are each independently ##STR74## Y and L are each independently H or F, X is F, Cl, --CF.sub.3, --CHF.sub.2, --OCF.sub.3, --OCHF.sub.2, --OCF.sub.2 CF.sub.2 H or --OC.sub.2 F.sub.5, and
- n is 0 or 1;
- b) contains 0-40% by weight of a liquid-crystalline component B, comprising one or more compounds having a dielectric anisotropy of -1.5 to +1.5 at 20.degree. C., of formula I ##STR75## wherein R.sup.1 and R.sup.2 are each independently n-alkyl, n-alkoxy, n-oxaalkyl, straight-chain .omega.-fluoroalkyl or n-alkenyl having up to 9 carbon atoms,
- A.sup.1, A.sup.2 and A.sup.3 are each independently 1,4-phenylene, 2- or 3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene or 1,4-cyclohexenylene,
- 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 and 2;
- c) contains 0-5% by weight of a liquid-crystalline component C, comprising 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 the natural pitch of the chiral nematic liquid-crystal mixture is 0.2 to 1.3;
- and
- said nematic liquid-crystal mixture has a nematic phase range of at least 60.degree. C., a viscosity of not more than 35 mPa.s at 20.degree. C. and a dielectric anisotropy of at least +1 at 20.degree. C.
12 more elements
Dependencies are inferred from the claim text.