Abstract: Liquid crystal compositions having a small value of .gamma. (V.sub.10 /V.sub.90) and a small .tau. (fast response speed) in order to cope especially with high speed response, while satisfying various characteristics required of STN display mode. These compositions comprise at least one compound expressed by formula (I) as a first component; expressed by any one of formulas (II-a) to (II-d) as a second component; and expressed by formula (III) or (IV) as a third component; and as a fourth component, a chiral component in the amount necessary for maintaining the ratio d/P of the cell thickness d (.mu.m) to the pitch length of twist P (.mu.m) in the range of 0.4 to 0.6 when the liquid crystal composition is used for liquid crystal display devices. ##STR1## wherein R.sup.1 to R.sup.9 represent an alkyl group having 1 to 10 carbon atoms; Z.sup.0 to Z.sup.4 represent, for example, --CH.sub.2 CH.sub.2 --; A.sup.1 to A.sup.

Abstract: A liquid crystal composition comprising, for example, a first component of the formula (1-2), a second component of the formula (2-a) and a third component of the formulas (3) and (4), the respective contents being 3 to 30%, 10 to 60% and 20 to 80%, each by weight, ##STR1## wherein R, R.sup.1, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 each independently represent an alkyl group of C.sub.1-10 or an alkenyl group of C.sub.2-10 ; R.sup.7 represents an alkyl group, an alkenyl group or an alkoxymethyl group of C.sub.1-10 ; B.sup.1, C, D and J represent 1,4-cyclohexylene or 1,4-phenylene; E represents 1,4-cyclohexylene or pyrimidine-2,5-diyl; G represents 1,4-cyclohexylene or 1,4-phenylene wherein H at the lateral positions may be replaced by F; Z.sup.1 and Z.sup.6 represent --COO--, --C.sub.2 H.sub.4 -- or a single bond; and Z.sup.5 and Z.sup.7 represent --C--C-- or a single bond.

Abstract: A liquid crystal composition which comprises 1 to 15% of a first component (a compound selected from compounds of the formulae I-a and I-b), 8 to 40% of a second component (a compound of the formula II), 10 to 30% of a third component (a compound of the formula III), and 10 to 45% of a fourth component (a compound selected from compounds of the formulae IV-a, IV-b, IV-c and IV-d) ##STR1## wherein each of R.sup.1, R.sup.2, R.sup.8 and R.sup.12 is a C.sub.1 -C.sub.10 alkyl group, R.sup.3 is a C.sub.1 -C.sub.10 alkyl group or a C.sub.2 -C.sub.10 alkenyl group, each of R.sup.4, R.sup.7 and R.sup.11 is a C.sub.1 -C.sub.10 alkyl group or alkoxy group, each of R.sup.5 and R.sup.9 is a C.sub.2 -C.sub.10 alkenyl group or alkenyloxy group, each of R.sup.6 and R.sup.10 is a C.sub.2 -C.sub.10 alkenyl group, and R.sup.13 is a C.sub.2 -C.sub.10 alkoxyalkyl group.

Abstract: A chiral, nematic liquid crystal composition suitable to STN-LCD, having superior steepness, rapid response and being able to prevent occurrence of high order and low order domain of LCD, which composition contains as a first component, at least one compound expressed by the formula (1) ##STR1## as a second component, at least one compound expressed by the formula (2) ##STR2## and as a third component, at least one compound of benzonitrile group, ##STR3## and further having a chiral dopant as a fourth component. In the above formulas, R.sup.1 and R.sup.2 each represent a linear alkyl group of 1 to 10 carbon atoms, A and B each represent trans-1,4-cyclohexylene or 1,4-phenylene, and R.sup.3 represents a linear alkyl group of 1 to 10 carbon atoms, or a group wherein an optional --CH.sub.2 -- or two or more not adjacent --CH.sub.2 --s present in the above group are replaced by --O-- or --CH=CH--; X.sup.1 and X.sup.2 each independently represent H or F; C represents --COO--, --C.sub.2 H.sub.

Abstract: A liquid crystal composition which is a liquid crystal mixture of an achiral liquid crystal compound of the following formula (IV) with a chiral compound having an adsorptivity to adsorbents, not greater than that of the achiral compound: ##STR1## wherein six-membered rings A', B', C' and D' each independently are trans-1,4-cyclohexylene, 1-cyclohexene-1,4-diyl or 1,4-phenylene; g, h and i each are 0 or 1; (g+h+i).gtoreq.1; X', Y' and Z' each independently are a single bond, --CH.sub.2 --CH.sub.2 --, --CH.dbd.CH-- or --C.tbd.C--; R.sup.7 is C.sub.n H.sub.2n+1 --, C.sub.n H.sub.2n-1 or C.sub.n H.sub.2n+1 OC.sub.k H.sub.2k --; R.sup.8 is C.sub.m H.sub.2m+1 --, C.sub.m H.sub.2m+1 O--, F, CHF.sub.2 O or CF.sub.3 O--; n and m each independently are an integer of 1 to 18; k is an integer of 1 to 17; (n+k) is 2 to 18; at least one of X', Y' and Z' is single bond; when ring D' is 1,4-phenylene and R.sup.8 is F, CHF.sub.2 O-- or CF.sub.3 O--, then H at ortho position as regards R.sup.

Abstract: A ferroelectric liquid crystal composition is provided which includes at least one achiral compound represented by formula (I) ##STR1## wherein each of R.sup.1 and R.sup.2 is an alkyl group having 1 to 18 carbon atoms, at least one optically active compound represented by formula (II) ##STR2## wherein R.sup.3 is an alkyl group or an alkoxy group having 1 to 18 carbon atoms, R.sup.4 is an alkyl group having 2 to 18 carbon atoms, X is a single bond, --COO--, --OCO--, --N.dbd.CH--, --CH.dbd.N--, --OCH.sub.2 -- or --CH.sub.2 O--, each of m and n is an integer of 1 or 2, and the symbol * is an asymmetric carbon atom, and at least one compound represented by formula (III) ##STR3## wherein each of ##STR4## R.sup.5 is an alkyl group or an alkoxy group having 1 to 18 carbon atoms, Y is a single bond, --CH.sub.2 O-- or --OCH.sub.2 --, p is an integer of 0 or 1, and Z is an alkyl group having 1 to 18 carbon atoms or --C*H(CH.sub.3)--O--R.sup.6, wherein R.sup.

Abstract: The present invention provides a ferroelectric liquid crystal composition wherein the phase transition series of the composition assumes an order of isotropic liquid.fwdarw.cholesteric phase.fwdarw.chiral smectic C phase starting from the high temperature and to a switching element good in contrast, and memory properties using the same. The composition comprises a composition that contains a component A of a compound having the formula: ##STR1## and/or a compound having the formula: ##STR2## wherin R.sup.1 and R.sup.2 represent each an alkyl group having 1 to 18 carbon atoms;a component B of a compound of the formula: ##STR3## a component C of a compound of the formula: ##STR4## and a component D of a compound of the formula: ##STR5## wherein R.sup.3, R.sup.4, R.sup.5, R.sup.7, and R.sup.

Abstract: A ferroelectric liquid crystal composition is here provided which contains at least one chiral compound having an optical activity site group represented by the general formula (I) ##STR1## wherein R.sup.1 is a straight-chain or branched alkyl group or alkoxy group having 1 to 18 carbon atoms, and * indicates an asymmetric carbon atom, and at least one non-chiral compound having a smectic C phase, a smectic I phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic J phase or a smectic K phase. This composition has quick response properties and assumes an SC* phase in an extensive temperature range inclusive of room temperature. Furthermore, by using this composition, an optical switching element having quick responsiveness can be obtained.

Abstract: A ferroelectic smectic C liquid crystal mixture and a display element having a quick electrooptical response and a good memory property are provided, the ferroelectric mixture having a Ps of 60 nC/cm2 or more and a tilt angle of 24.degree. or more and comprising(A) a first component comprising at least one optically active compound expressed by the formula ##STR1## wherein l and m are 0 or 1, both are not 1; n is an integer of 3 to 8; X and Y are H, F, Cl, or CN, both X and Y are not H; A is --COO-- or --OCO--; and R is C3--8 alkyl or alkoxy , and(B) a second component comprising at least one optically active compound expressed by the formula ##STR2## wherein l, m, n and R are as defined above; and A is --COO--, --OCO--, --CH.sub.2 O-- or --OCH.sub.2 --, a total content of the first and second components being 60 mol % or more in the mixture.

Abstract: The present invention is directed to a ferroelectric liquid crystal composition having quick response properties and assuming a smectic C* phase in an extensive temperature range inclusive of room temperature, and an optical switching element having a quick response property containing this composition.The ferroelectric liquid crystal composition is here disclosed which comprises at least one chiral compound (liquid crystal component A) having an optical activity site represented by the formula (A) ##STR1## wherein R.sup.1 is a straight-chain or branched alkyl group having 2 to 18 carbon atoms or a straight-chain or branched alkoxy group having 1 to 18 carbon atoms, and * indicates an asymmetric carbon atom,and at least one non-chiral compound (liquid crystal component B) having a smectic C phase (hereinafter referred to as "S.sub.C phase"; which shall apply in the following), an S.sub.I phase, an S.sub.F phase, an S.sub.G phase, an S.sub.H phase, an S.sub.J phase or an S.sub.K phase.

Abstract: A ferroelectric liquid crystal composition having a negative large dielectric anisotropy value, AC stabilizing effect at low voltages and yet high-speed response properties, and a light switching element using the composition are provided, which composition comprises at least two components at least one of which is a compound expressed by the formula ##STR1## wherein R.sup.3 and R.sup.4 each represent the same or different linear or branched alkyl group of 1-18C and l is 1 or 2, and having a negative dielectric anisotropy value.A preferred embodiment of the above composition contains at least three components A, B and C, one of which is the above compound of the formula (A) and components B and C of which are each selected from a group of specified compounds, and the respective proportions of components A, B and C being 5-50 weight %, 20-70 weight % and 5-40 weight % based on the total weight of the three, respectively.

Abstract: A ferroelectric liquid crystal composition is here provided which contains at least one chiral compound having an optical activity site group represented by the general formula (I) ##STR1## wherein R.sup.1 is a straight-chain or branched alkyl group or alkoxy group having 1 to 18 carbon atoms, and * indicates an asymmetric carbon atom, and at least one non-chiral compound having a smectic C phase, a smectic I phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic J phase or a smectic K phase. This composition has quick response properties and assumes an SC* phase in an extensive temperature range inclusive of room temperature. Furthermore, by using this composition, an optical switching element having quick responsiveness can be obtained.

Abstract: A ferroelectric liquid crystal composition having a negative dielectric anisotropy, a good AC-stabilizing effect and still high-speed response properties, and a light switching element, are provided, which composition comprises a compound expressed by the formula ##STR1## wherein R.sup.1 and R.sup.2 each represent a linear or branched alkyl group, alkoxy group, alkanoyloxy group, alkoxycarbonyl group, alkoxycarbonyloxy group or alkanoyl group each of 1 to 18 carbon atoms; ##STR2## X.sub.1, X.sub.2 and X.sub.3 each represent hydrogen atom or halogen atom; P and Q each represent 0 or 1; and P+Q is 0 or 1.

Abstract: Disclosed is an improvement of an active matrix type liquid crystal display device using a combination of a specific mixed liquid crystal and a specific polyimide orientation film.

Abstract: The present invention relates to a ferroelectric liquid crystal composition having quick response and comprising a smectic liquid crystal compound and an optically active compound.The ferroelectric liquid crystal composition comprises components A and B, said component A comprising a compound represented by the formula: ##STR1## and/or a compound represented by the formula: ##STR2## said component B comprising a compound represented by the formula: ##STR3## and/or a compound represented by the formula: ##STR4## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.5 are each an alkyl or alkoxy group of 1 to 18 carbon, R.sup.4 and R.sup.6 are each an alkyl group of 2 to 18 carbon atoms or an alkoxy group of 1 to 18 carbon atoms, X and Y are each --CH.sub.2 O--, --OCH.sub.2 --, ##STR5## m, n, k and l are each an integer of 1 or 2 and * is an asymmetric carbon atom, the component A to component B ratio being 1.5 or less.

Abstract: A ferroelectric smectic C liquid crystal mixture having a smectic A phase region within 30.degree. C. on the higher temperature side relative to a chiral smectic C phase and also having a tilt angle at its chiral smectic C phase in the range of 30.degree. to 60.degree..

Abstract: A ferroelectric liquid crystal composition exhibiting SC* phase within a broad temperature range including room temperature and also having high-speed response properties and a light switching element using the above-mentioned liquid crystal composition and exhibiting high-speed response properties are provided, which composition comprises at least one member of chiral compounds expressed by the formula ##STR1## wherein R.sup.1 and R.sup.2 each represent a linear or branched chain alkyl, alkoxy, alkoxyalkoxy, alkoxycarbonyl, alkanoyl or alkanoyloxy group each of 1 to 18 C and at least one of R.sup.1 and R.sup.2 has an asymmetric carbon atom in the alkyl chain moiety of these groups, and at least one member of chiral compounds having a spontaneous polarization value of 40 nC/cm.sup.2 or more.

Abstract: A smectic C liquid crystal mixture having a broad smectic C phase temperature range including room temperature, a ferroelectric smectic C liquid crystal mixture having a large spontaneous polarization, comprising the above smectic C mixture and at least one optically active compound, and a liquid crystal display element having an improved response time, containing the above ferroelectric smectic C liquid crystal mixture are provided, which smectic C liquid crystal mixture comprises(1) at least two components at least one of which is a pyrimidine compound expressed by the formula ##STR1## wherein R.sup.1 represents a linear alkyl group of 4 to 20 carbon atoms and R.sup.2 represents a linear alkyl group having 7-20 carbons and having a smectic C phase;(2) at least one pyrimidine compound of the formula (I) and at least one pyrimidine compound expressed by the formula ##STR2## wherein R.sup.3 represents a linear alkyl group of 6 to 12 carbon atoms and R.sup.

Abstract: A ferroelectric liquid crystal composition exhibiting SC* phase within a broad temperature range including room temperature and yet having cholesteric phase and further high-speed response properties and a light switching element using the above composition and having high-speed response properties are provided, which composition comprises an achiral compound expressed by the formula ##STR1## wherein R.sup.1 and R.sup.2 each represent the same or different linear or branched chain alkyl group of 1 to 18 carbon atoms, in 20 to 70% by weight and having cholesteric phase; and which composition may further comprise at least one member of optically active compounds selected from four specified pyrimidine compounds.

Abstract: A ferroelectric liquid crystal composition comprising smectic liquid crystal compound(s) and optically active compound(s) and having high-speed response properties and a light switching element containing the same are provided, which composition comprises the following three liquid crystal components A, B and C, the respective proportions thereof being 10 to 70%, 10 to 50% and 10 to 40% each by weight based on the total weight of these components, respectively:liquid crystal component A:at least one compound selected from compounds of the formula ##STR1## wherein R.sup.1 and R.sup.2 each are 1-18C alkyl, and compounds of the formula ##STR2## wherein R.sup.3 and R.sup.4 each are 1-18C alkyl or alkoxy; liquid crystal compound B:at least one compound of the formula ##STR3## wherein R.sup.5 is a 1-18C alkyl, n is an integer of 0 to 10 and * indicates asymmetric carbon; andliquid crystal component C:at least one compound selected from compounds of the formula ##STR4## wherein R.sup.