Abstract: Liquid crystal phases containing at least one optically active compound of the formula I ##STR1## wherein X.sup.1 and X.sup.2 independently of one another are each --CO--O-- or --O--CO--, one of X.sup.1 and X.sup.2 may also be --O--,R.sup.1 and R.sup.2 independently of one another are each a group --(A.sup.1 --Z).sub.m --(A.sup.2).sub.n --Y,whereinA.sup.1 and A.sup.2 in each case independently of one another are a 1,4-phenylene, pyrimidine-2,5-diyl, pyrazine-2,5-diyl, pyridine-2,5-diyl, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5-diyl or 1,4-bicyclo(2,2,2)-octylene group, it also being possible for this to be monosubstituted or polysubstituted by F, Cl, Br, CN and/or alkyl groups with up to 12 C atoms, and it being possible for 1 or 2 non-adjacent CH.sub.2 groups in the alkyl groups to be replaced by 0 atoms, Z is --CO--O--, --O--CO--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 --, --CH.sub.2 O--, --CH.dbd.N--, --N.dbd.CH--, --N.dbd.N--, --N(O).dbd.

Abstract: The novel esters of a chiral alcohol and a mesogenic carboxylic acid are characterized by the general formula (I) ##STR1## in which the symbols have the following meanings: n denotes 0 or 1,R.sup.1 denotes a straight-chain or branched (C.sub.1 -C.sub.4)alkyl which is unsubstituted or substituted by halogen, in particular fluorine,R.sup.2 denotes unsubstituted or substituted (C.sub.6 -C.sub.18)aryl, cyclo(C.sub.5 -C.sub.12)alkyl or mononuclear or binuclear heteroaryl possessing a five-membered and/or six-membered ring, andMC denotes a molecular radical of a mesogenic monocarboxylic acid MC-OH after elimination of an OH group where n=0, and denotes a molecular radical of a mesogenic dicarboxylic acid HO-MC-OH after elimination of two OH groups where n=1, with the exception of compounds in which n denotes 0, R.sup.1 denotes CH.sub.3, R.sup.

Abstract: The chiral smetic liquid-crystalline compounds of the general formula (I)M.sub.1.sup.* --B--M.sub.2.sup.* (I)solidify on cooling from the liquid-crystalline phase in glassy form, as a result of which they are suitable for materials for displaying and storing information. Such materials may be used in electro-optic data stores or display components which are based on the ferroelectric or electroclinic switching effect in a chiral or chirally doped, smetic liquid-crystalline phase.In the general formula, M.sub.1.sup.*, M.sub.2.sup.* stand for chiral smetogenic groups and --B-- is, as bridging link, a typical bivalent group.

Abstract: The twistable liquid crystal phases contain at least two chiral compounds (admixtures), at least one exhibiting helix inversion and at least one other having a high twisting capacity. With the aid of this combination of chiral compounds possessing certain properties, it is possible to effect temperature compensation with a relatively small amount of added admixtures.

Abstract: The novel esters of a chiral alcohol and a mesogenic carboxylic acid are characterized by the general formula (I) ##STR1## in which the symbols have the following meanings: n denotes 0 or 1,R.sup.1 denotes a straight-chain or branched (C.sub.1 -C.sub.4)alkyl which is unsubstituted or substituted by halogen, in particular fluorine,R.sup.2 denotes unsubstituted or substituted (C.sub.6 -C.sub.18)aryl, cyclo(C.sub.5 -C.sub.12)alkyl or mononuclear or binuclear heteroaryl possessing a five-membered and/or six-membered ring, andMC denotes a molecular radical of a mesogenic monocarboxylic acid MC-OH after elimination of an OH group where n=0, and denotes a molecular radical of a mesogenic dicarboxylic acid HO-MC-OH after elimination of two OH groups where n=1, with the exception of compounds in which n denotes 0, R.sup.1 denotes CH.sub.3, R.sup.

Abstract: The new esters derived from a chiral compound containing two OH groups and at least one mesogenic carboxylic acid which have the general formula (I) ##STR1## in which X.sup.1 =O--H or O--CO--(C.sub.1 to C.sub.12)alkyl and X.sup.2 =O--MC or X.sup.1 and X.sup.2 denote O-MC independently of each other, where MC is the molecular radical of a mesogenic monocarboxylic acid after splitting off an OH group.The esters or esters substituted in the aromatic part of the phenolic part preferably find application as an admixture intwistable liquid crystal phases in which they produce a temperature compensation and a high degree of twisting.

Abstract: The circular polarizer comprises a liquid crystal cell, the liquid crystal layer (8) of which is present as a so-called "blue phase" and can be exposed to a variable electric field. The blue phase is an optically isotropic chiral phase which, like the cholesteric phase, reflects circularly polarized light within a narrow frequency band and accordingly, in this spectral region, transmits only light which is circularly polarized (in the opposite sense). Under the influence of the field, the reflection band changes its position and can be shifted almost continuously from blue to red by means of relatively small voltage changes.The circular polarizer can, by means of simple additional measures, for instance by including a color-neutral circular polarizer, be developed into a color modulator and, in particular, it also makes a multi-colored display of information possible.

Abstract: An optical system contains a liquid crystal cell (1), to the liquid crystal layer (11) of which an E-field can be applied transversely to the plane of the layer. A light source (3) sends to the liquid crystal cell (1) a beam of rays parallel to the field direction. The liquid crystal is in the form of a chiral, optically isotropic phase ("blue phase"). This phase has a field-dependent optical density for the incident light and is matched to the light wavelength such that no selective reflection takes place. Such a cell is also optically isotropic in the presence of an E-field, switches rapidly and requires no interface orientation. Its preferred fields of use are: intensity modulation of light of a given wavelength, or as a phase grid in a schlieren-optical system, an etalon in a laser, or a light switch.

Abstract: Liquid crystal phases containing at least one optically active compound of the formula IR.sup.1 --X.sup.1 --CHR.sup.o (CH.sub.2).sub.p X.sup.2 --R.sup.2 Iwherein X.sup.1 and X.sup.2 independently of one another are each --CO--O-- or --O--CO--, one of X.sup.1 and X.sup.2 may also be --O--, R.sup.1 and R.sup.2 independently of one another are each a group --(A.sup.1 --Z).sub.m --(A.sup.2).sub.n -Y, whereinA.sup.1 and A.sup.2 in each case independently of one another are a 1,4-phenylene, pyrimidine-2,5-diyl, pyrazine-2,5-diyl, pyridine-2,5-diyl, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5-diyl or 1,4-bicyclo(2,2,2)-octylene group, it also being possible for this to be monosubstituted or polysubstituted by F, Cl, Br, CN and/or alkyl groups with up to 12 C atoms, and it being possible for 1 or 2 non-adjacent CH.sub.2 groups in the alkyl groups to be replaced by O atoms,Z is --CO--O--, --O--CO--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 --, --CH.sub.2 O--, --CH.dbd.N--, --N.dbd.CH--, --N.dbd.N--, --N(O).

Abstract: Liquid crystal phases containing at least one chiral, compound with at least two chiral centers in the molecule which are adjacent or separated from one another by an acyclic chain, preferably at least one optically active compound of the formula IR.sup.1 --CHCH.sub.3 --CHCH.sub.3 --R.sup.2 IwhereinR.sup.1 and R.sup.2 independently of one another are each a group --Z.sup.1 --(A.sup.1).sub.m --Z.sup.2 --(A.sup.2).sub.n --Y, whereinA.sup.1 and A.sup.2 in each case independently of one another are a 1,4-phenylene, pyrimidine-2,5-diyl, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5-diyl or 1,4-bicyclo(2,2,2)-octylene group, it also being possible for these to be mono-substituted or poly-substituted by F, Cl, Br, CN and/or alkyl groups with up to 12 C atoms, it being possible for 1 or 2 CH.sub.2 groups in the alkyl groups to be replaced by O atoms,Z.sup.1 is --O--CO--, --CO--O--, --O-- or a single bond,Z.sup.2 is --CO--O--, --O--CO--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 --, --CH.sub.2 O--, --CH.dbd.

Abstract: An operable liquid crystal display device having threshold energy fields dependent on a finite temperature operating range is provided with a layer of a liquid crystal material positioned between the carrier plates of such device. The liquid crystal material includes a nematic carrier material and at least two doping chiral additives, one of which exhibits a clockwise twisting tendency and the other which exhibits a couter-clockwise twisting tendency. The twisting characteristic for the cholesteric phase has a temperature-dependent pitch and, under certain conditions, a temperature-dependent direction of rotation.