Supertwist liquid-crystal display
AssigneeMerck Patent GmbH
InventorsVolker Reiffenrath, Bernhard Rieger, Michael Junge, Martina Schmidt, Christine Pfister
Life of this patent
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Abstract
Supertwist liquid crystal displays with outstanding properties are obtained when the nematic liquid crystal mixture contains at least one compound of the formula (I): ##STR1## where the variables are as defined in the disclosure.
Claims19
Supertwist liquid-crystal display containing
- 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 the cell,
- electrode layers with superposed alignment layers on the inside 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 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 100 and 600.degree.,
- a nematic liquid-crystal mixture consisting of
- 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) 10-65% 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 an amount such that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the chiral nematic liquid-crystal mixture is from about 0.2 to 1.3, wherein
- component B comprises at least one compound of the formula I ##STR238## in which ##STR239## R.sup.1 is an alkyl, alkoxy or alkenyl radical having 1 to 10 carbon atoms which is unsubstituted or monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, optionally one or more CH.sub.2 groups in this radical being replaced by --O--,
- R.sup.2 is (CH.sub.2).sub.n --CH.dbd.CH--R.sup.2 or (CH.sub.2).sub.n --CH.dbd.CH.sub.2, and, in the case where R=1, R.sup.2 is alternatively R.sup.a,
- R.sup.a is a straight-chain alkyl having 1-6 carbon atoms,
- n is 0-6,
- p is 0 or 1,
- r is 0, or 1 and
- s is 1 or 2.
A compound of the formula ##STR252## in which R.sup.1 is an alkyl, alkoxy or alkenyl radical having 1 to 10 carbon atoms which is unsubstituted or monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, optionally one or more CH.sub.2 groups in this radical being replaced by --O--,
- and
- R.sup.2 is (CH.sub.2).sub.n --CH.dbd.CH--R.sup.2 or (CH.sub.2).sub.n --CH.dbd.CH.sub.2, where R.sup.2 is a straight chain alkyl of 1 to 6 carbon atoms and n is from 0 to 6.
A compound of the formula IB ##STR253## in which R.sup.1 is an alkyl, alkoxy or alkenyl radical having 1 to 10 carbon atoms which is unsubstituted or monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, optionally one or more CH.sub.2 groups in this radical being replaced by --O--, and alkyl is an alkyl radical having 1-6 carbon atoms.
A compound of the formula IC ##STR254## in which R.sup.2 is (CH.sub.2).sub.n --CH.dbd.CH--R.sup.a or (CH.sub.2).sub.n --CH.dbd.CH.sub.2 or R.sup.a, where R.sup.a is a straight chain alkyl of 1 to 6 carbon atoms, n is 0-6 and R.sup.b is H or alkyl having 1-6 carbon atoms.
A compound of the formula ID ##STR255## R.sup.b and R.sup.b' are each independently of one another H or alkyl having 1-6 carbon atoms, and
- n and o are each, independently of one another, 0-6.
A compound of the formula IE ##STR256## in which R.sup.2 is (CH.sub.2).sub.n --CH.dbd.CH--R.sup.a or (CH.sub.2).sub.n --CH.dbd.CH.sub.2 or R.sup.a, where R.sup.a is a straight chain alkyl of 1 to 6 carbon atoms, n is 0-6 and R.sup.b is H or alkyl having 1-6 carbon atoms.
A compound of the formula IF ##STR257## in which R.sup.2 is (CH.sub.2).sub.n --CH.dbd.CHR.sup.a or (CH.sub.2).sub.n --CH.dbd.CH.sub.2 or R.sup.a, where R.sup.a is a straight chain alkyl or 1 to 6 carbon atoms, n is 0-6, and R.sup.b is H or alkyl having 1-6 carbon atoms.
A compound of the formula IG ##STR258## in which R.sup.1 is an alkyl, alkoxy or alkenyl radical having 1 to 10 carbon atoms which is unsubstituted or monosubstituted by CN or CF.sub.2 or at least monosubstituted by halogen, optionally one or more CH.sub.2 groups in this radical being replaced by --O--, n is 0-6, R.sup.b is H or alkyl having 1-6 carbon atoms, and L.sup.1 and L.sup.2 are H or F.
A compound of the formula ##STR259## in which R.sup.1 is an alkyl, alkoxy or alkenyl radical having 1 to 10 carbon atoms which is unsubstituted or monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, optionally one or more CH.sub.2 groups in this radical being replaced by --O--,
- R.sup.2 is (CH.sub.2).sub.n --CH.dbd.CH--R.sup.2 or (CH.sub.2).sub.n --CH.dbd.CH.sub.2 or R.sup.2, where R.sup.2 is a straight chain alkyl of 1 to 6 carbon atoms, n is from 0 to 6,
- and ##STR260##
Compounds of the formula in which
- alkyl is C.sub.1-6 -alkyl and
- R.sup.b is H or alkyl having 1-6 carbon atoms.
A nematic liquid-crystal mixture consisting of
- a) 20-90% by weight of a liquid-crystalline component A consisting of one or more compounds having a dielectric anistropy of greater than +1.5;
- b) 10-65% 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 compound having a dielectric anisotropy of below -1.5, and
- d) an optically active component C in an amount such that the ratio between the layer thickness (separation of the plane-parallel outer plates) and the natural pitch of the chiral nematic liquid-crystal mixture is from about 0.2 to 1.3, wherein component B comprises at least one compound of the formula I ##STR261## in which ##STR262## R.sup.1 is an alkyl, alkoxy or alkenyl radical having 1 to 10 carbon atoms which is unsubstituted or monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, optionally one or more CH.sub.2 groups in this radical being replaced by --O--,
- R.sup.2 is (CH.sub.2).sub.n --CH.dbd.CH--R.sup.a or (CH.sub.2).sub.n --CH.dbd.CH.sub.2, and, in the case where r=1, is alternatively R.sup.a,
- R.sup.a is a straight-chain alkyl having 1-6 carbon atoms,
- n is 0-6,
- p is 0 or 1,
- r is 0 or 1 and
- s is 1 or 2.
Dependencies are inferred from the claim text.