Ferroelectric liquid crystal display

A ferroelectric liquid crystal device having a pair of substrates each provided with voltage applying means, an orientation control layer formed on at least one of the substrates, and a layer of ferroelectric liquid crystal composition disposed between the pair of substrates, the ferroelectric liquid crystal composition comprising at least one compound (a) having an optically active group of formula (I):

• ##STR130## at least one compound (b) which is reverse to the compound (a) in the direction of a helical pitch induced in a nematic phase and at least one liquid crystal compound (c) exhibiting a smectic C phase, the liquid crystal composition exhibiting at least a smectic C phase, smectic A phase and nematic phase, wherein the ferroelectric liquid crystal composition comprises the optically active compounds (II) and (III):
• ##STR131## wherein A.sup.1, A.sup.2, A.sup.3 are each a group containing a 6-membered ring having group selected from the group consisting of benzene, piperazine, cyclohexane, dioxacyclohexane and naphthalene, each of which is unsubstituted or substituted with one or more substituents of fluorine, chlorine, bromine, cyano, nitro, methyl or methoxy, X is --O--, --COO--, --OCO-- or a single bond, Y.sup.1 and Y.sup.2 are each --COO--, --OCO--, --OCH.sub.2 --, --CH.sub.2 O--, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, --C.tbd.C-- or a single bond, R.sup.1, R.sup.2 are each straight-chain or branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, and p, q and r are each an integer of 0 to 1, and ##STR132## wherein A.sup.4, A.sup.5, A.sup.6 are each a group containing a 6-membered ring having group selected from the group consisting of benzene, piperazine, cyclohexane, dioxacyclohexane and naphthalene, each of which is unsubstituted or substituted with one ore more substituents of fluorine, chlorine, bromine, cyano, nitro, methyl or methoxy, X is --O--, --COO--, --OCO--, or a single bond, Y.sup.4 and Y.sup.5 are each --COO--, --OCO--, --OCH.sub.2 --, --CH.sub.2 O--, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, --C.tbd.C-- or a single bond, R.sup.3 and R.sup.4 are each straight-chain or branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, and p, q and r are each an integer of 0 to 1, and
• wherein one of the compounds (II) and (III) being active as the compound (a) and another being active as the compound (b), and
• wherein the liquid crystal compound (c) is represented by the formula (IV):
• ##STR133## wherein R.sup.9 and R.sup.10 each represent an alkyl or alkoxy group having 1 to 15 carbon atoms and k denotes an integer of 0 or 1;
• or
• wherein the liquid crystal compound (c) is represented by the formula (V):
• ##STR134## wherein R.sup.11 and R.sup.12 each represents an alkyl or alkoxy group having 1 to 15 carbon atoms with straight or branched-chain ##STR135## each represents a group ##STR136## l, m and n each denotes an integer of 0 or 1, provided that the total of l, m and n is 1, 2 or 3;
• or
• wherein the compound (c) is at least one optically active compound of the formulae (VII), (VIII) and (IX):
• ##STR137## wherein B.sup.1, B.sup.2 and B.sup.3 are independently a 6-membered cyclic ring having group selected from the group consisting of benzene, cyclohexane, bicyclo[2.2.2]octane, pyridine, pyrimidine, pyrazine, dioxacyclohexane, and naphthalene, each of which is unsubstituted or substituted with one or more substituents of fluorine, chlorine, bromine, cyano, nitro, methyl, methoxy, trifluoromethyl;
• D.sup.1 and D.sup.2 each represent a single bond or --COO--, --OCO--, --CH.dbd.CH--, --C.tbd.C--, --CH.dbd.CH--COO--, --OCO--CH.dbd.CH--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 -- --CH.sub.2 O--, --COS-- or --SCO--;
• Z.sup.1 and Z.sup.2 are each a single bond or --COO--, --OCO--, --O--, --S--, --OCOO-- or --CO--;
• R.sup.7 and R.sup.8 are each straight-chain or branched-chain alkyl group having 1 to 15 carbon atoms and containing 0 to 1 asymmetric carbon atom, each of which is unsubstituted or substituted with one or more substituents of fluorine, chlorine, bromine, cyano, nitro, methoxy, or trifluoromethyl;
• and s is an integer of 1 or 2.