Abstract: Optically active, mesogenic 1,3-dioxolane-4-carboxylates are suitable as dopes in liquid-crystal mixtures. They result in liquid-crystalline ferroelectric phases having short switching times and in electroclinic phases having large electroclinic coefficients. Their particular advantage is that they induce a helix of very large pitch, meaning that helix compensation by further dopes is unnecessary. In addition, the 1,3-dioxolane-4-carboxylates exhibit high UV stability.

Abstract: Ferroelectric liquid-crystal systems having high spontaneous polarization, in particular >35 nC cm.sup.-2, and good orientation properties in the ferroelectric phase, in particular the S.sub.C * phase, contain at least three different optically active compounds, preferably as dopes in a base mixture which is not itself optically active and has a nematic phase above the smectic phase. The optically active compounds are selected so that they do not all induce a helix of the same rotation sense in the nematic phase. Their relative concentrations are selected so that the total resultant pitch of the helix throughout the cholesteric phase is not less than 10 .mu.m.

Abstract: Disclosed and claimed are liquid-crystalline cyclopropylalkyl or -alkenyl or heterocyclic compounds, process for their preparation, and their use in liquid-crystalline mixtures. The novel cyclopropylalkyl or -alkenyl or heterocyclic compounds are of the general formula ##STR1## In this formula A.sup.1, A.sup.2 and A.sup.3 are unsubstituted or substituted, aromatic or heteroaromatic molecular components such as 1,4-phenylene or pyrimidine-2,5-diyl which are linked via a single bond (in the case where k and m=0) or via functional groups M.sup.1 and M.sup.2, such as CO--O or CH.sub.2 --O; j, k, l, m and n are zero, 1 or 2. The radicals R.sup.2, R.sup.3 and R.sup.4 are H or alkyl/alkenyl, R.sup.1 is alkyl/alkenyl or one of the substitutents known from LC chemistry such as an .alpha.-haloalkanoic acid radical. At least one of the components A.sup.1, A.sup.2 and A.sup.3 can be heteroaromatic, and G is alkylene or alkenylene.

Abstract: The use of optically active tetrahydrofuran-2-carboxylic acid esters as dopants in liquid-crystal mixtures, liquid-crystal mixtures containing same and novel optically active tetrahydrofuran-2-carboxylic acid esters.Optically active tetrahydrofuran-2-carboxylic acid esters containing a mesogenic molecular building unit are suitable as dopants in liquid-crystal mixtures. They result in liquid-crystalline ferroelectric phases having short switching times and in electroclinic phases having large electroclinic coefficients. A further advantage is that they induce a helix having a very small pitch so that they are also suitable for helix compensation in LC mixtures.The compounds are symbolized by the general formula: ##STR1## in which the symbols and indices essentially denote: R.sup.1 =alkyl/alkenyl or tetrahydrofurancarbonyloxy or -thio; j, l, n=zero, 1 or 2; k, m=zero or 1; --A.sup.1, --A.sup.2, --A.sup.3 =phenylene, cycloalkylene or corresponding heterocyclates containing nitrogen, oxygen or sulfur; --M.sup.

Abstract: Ferroelectric liquid-crystal display of high contrast and brightness. The use of alignment layers containing compounds having an amphiphilicity-providing effect increases the contrast and brightness of the image in FLC displays.

Abstract: The novel ferroelectric liquid-crystalline mixtures are based on at least two mixture components of the general formula (I) ##STR1## but additionally contain at least one optically active dope from one or more of the following groupsa) optically active esters of tetrahydrofuran-2-carboxylic acidb) optically active aryl 2,3-epoxyalkyl ethersc) optically active 1,3-dioxolan-4-yl ethers.The ferroelectric LC mixtures have a high spontaneous polarization and facilitate substantial compensation of the pitch of the helix in a nematic phase.

Abstract: Use of optically active carboxylic esters of oxygen-containing heterocycles as doping substances in liquid crystal mixtures and liquid crystal mixtures containing them.Optically active 1,3-dioxolane-4-carboxylic esters and oxirane-2-carboxylic esters of the general formula (I)R(--A.sup.1).sub.j (--M.sup.1).sub.k (--A.sup.2).sub.l (--M.sup.2).sub.m (--A.sup.3).sub.n --X--Acin whichR.sup.1 is, for example, (C.sub.1 -C.sub.16)-alkyl or (C.sub.1 -C.sub.16)-alkoxy,A.sup.1, A.sup.2, A.sup.3 are, for example, phenyl or pyrimidine-2, 5-diyl,M.sup.1, M.sup.2 are, for example, CO--O, CH.sub.2 --CH.sub.2,j, l are 0, 1, 2,k, m are 0, 1,n is 0, 1, 2,X is O, S andAc is ##STR1## in which R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 for example, H or methyl, are particularly suitable doping substances for liquid crystalline mixtures, since they induce a high spontaneous polarization and effect a substantial decrease in the melting point.

Abstract: A method of driving a ferroelectric liquid crystal element which enlarges the effective cone angle. A ferroelectric liquid crystal is held between two substrates such that the helix is suppressed and a chevron layer structure is present. The ferroelectric material has a positive dielectric anisotropy. A first pulse is applied which causes switching from one state to the other, and a subsequent smaller AC pulse is applied which does not cause switching. The second pulse voltage control the effective cone angle, enabling grey scale.

Abstract: The novel silylalkyl or silylalkenyl compounds correspond to the general formula (I) ##STR1## Here the symbols A.sup.1, A.sup.2, A.sup.3 denote aromatic or heteroaromatic molecular units such as 1,4-phenylene or pyrimidine-2,5-diyl which are combined via a single bond (for k, m=0) or via functional groups M.sup.1,M.sup.2 such as CO--O or CH.sub.2 --O; j, k, l, m, n are zero or 1 (j+l+n=2 or 3). The radicals R.sup.2, R.sup.3, R.sup.4, R.sup.5 are hydrogen or alkyl/alkenyl, cycloalkyl, and the radicals R.sup.6, R.sup.7, R.sup.8 have a comparable meaning (hydrogen); R.sup.1 is alkyl/alkenyl or one of the substituents known from LC chemistry such as an .alpha.-haloalkanoic radical. In some cases compounds have wide and polymorphous liquid crystalline phases.

Abstract: Use of fluorinated aromatic polyamides as orientation layer for liquid crystal switching and display devicesUse of substituted aromatic polyamides as orientation layer in liquid crystal switching and display elements is described, in which the polyamides contain structural units of the formula (I) ##STR1## in which in formula I the symbols have the following meaning: ##STR2## in which R.sup.1 and R.sup.2 are identical or different and are perfluorinated alkyl having 1 to 4 carbon atoms, R.sup.3 and R.sup.4 are identical or different and are H or CF.sub.3, and in which --W-- is, for example, --O--, --C(CH.sub.3).sub.2 --, --C(CF.sub.3).sub.2 --.Orientation layers made of these polyamides can be cured at low temperatures, have good adhesion and high transmittance and allow for a high surface tilt angle.

Abstract: Optically active 1,3-dioxolane derivatives of the general formula (I) ##STR1## are suitable as doping substances in liquid crystal mixtures. The symbols in the general formula have the following meaning:R.sup.1 has the structure which is analogous to the moiety of the general formula which is on the right of X or is an alkyl or alkylene radical which can be substituted, R.sup.2, R.sup.3 are H or alkyl, which can also be substituted [R.sup.2, R.sup.3 can also be a cycloaliphatic compound together with C(2) of the dioxolane ring],R.sup.4 is vinyl or ethyl, with the proviso that at least one radical R.sup.4 is vinyl or ethyl, if R.sup.1 is analogous to the moiety of the formula (I) which is on the right of X, --A.sup.1, --A.sup.2, --A.sup.3 are an aromatic, heterocyclic or aliphatic ring system,--M.sup.1, --M.sup.2 are --CO--O, --O--CO, --CH.sub.2 CH.sub.2, --CH.dbd.CH, --CH.sub.2 O, --OCH.sub.2, --C.dbd.C andX is O, S or O--CO--O.

Abstract: The novel liquid-crystalline mixtures (in the case of ferroelectric behavior they additionally contain an optically active compound as dope) are based on at least two mixture components of the general formula (I) and at least one carboxylate of the general formula (II), (III) or (IV). ##STR1## The mixtures have favorable properties for use in electrooptical display elements, such as high contrast, low melting point and short switching times.

Abstract: A ferroelectric liquid crystal switching or display device, in which the liquid crystal film has a constant thickness, wherein one of the glass sheets in the device is planar and the other glass sheet has at least one step. The switching or display device of the present invention does not require shortened switching times or more contacts or drivers and does not show unwanted switching.

Abstract: Preparation of specially substituted aromatic polyamides containing structural units of the formula I mentioned and copolyamides containing at least 10 mol % of structural units of the formula I and structural units of the formula II mentioned and their use as orientation layer in liquid crystal display elements and/or liquid crystal switching elements.

Abstract: Use of polyaryl ether ketones comprising structural units --O--A--O--B-- gives alignment layers for liquid-crystal display and switching devices which have high transparency, low water absorption capacity and particularly uniform alignment both of smectic and of nematic liquid crystals, and thus produce a high contrast capability.

Abstract: Switching and display elements based on ferroelectric liquid-crystals often exhibit a pronounced optical hysteresis which results in the appearance of so-called ghost images. This phenomenon can be markedly reduced or even suppressed if at least one of the two orienting layers are in direct contact with the electrodes and is composed of an electrically conductive polymer of the formula (I): ##STR1## in which R.sup.1, R.sup.2 =independently of each other, H, or straight-chain or branched alkyl or alkoxy containing 1-16 carbon atoms, or halogen,X=S, NH,Y.sup.- =BF.sub.4.sup.-, PF.sub.6.sup.-, PO.sub.4.sup.3-, AsF.sub.6.sup.-, SbCl.sub.6.sup.-, SO.sub.4.sup.2-, HSO.sub.4.sup.-, alkyl--SO.sub.3.sup.-, perfluoroalkyl--SO.sub.3.sup.-, aryl--SO.sub.3, F.sup.- or Cl.sup.-, andn is an integer from 4 to 100 andm is an integer from 1 to 30.

Abstract: The novel liquid-crystalline mixtures (in the case of ferroelectric behavior they additionally contain an optically active compound as dope) are constructed from at least 2 mixture components of the general formula (I): ##STR1## wherein n=6 to 14 and x=2 to 14. In addition, the mixtures may also contain cyclohexanecarboxylates of the general formula (II) ##STR2## where R.sup.1 =(C.sub.10 -C.sub.16) or (C.sub.8 -C.sub.14)alkoxy and R.sup.2 =(C.sub.2 -C.sub.9)alkyl, alkenyloxyphenylpyrimidine derivatives of the general formula (III) ##STR3## where R.sup.3 =(C.sub.7 -C.sub.16)alkyl or (C.sub.6 -C.sub.14)alkoxy and y=4-14, and/or alkoxyphenyl derivatives of alkylpyrimidine, of the general formula (IV) ##STR4## where m and p=6 to 14.

Abstract: Optically active oxirane-2-carboxylic acid esters with a mesogenic molecular component suitable as dopants in liquid-crystal mixtures. They result in liquid-crystalline ferroelectric phases with short switching times and in electroclinic phases with large electroclinic coefficients. A further advantage lies in the fact that they induce a helix with a very small pitch so that they are also suitable for helix compensation in LC mixtures.

Abstract: Arylcarboxylates of 2-hydroxypropionates are known, amongst other compounds, as dopes for converting tilted smectic liquid-crystal phases into ferroelectric liquid-crystal phases.The novel chiral aryloxypropionates of the general formula ##STR1## are two-fold chiral and in which the symbols have the following meaning: R.sup.1 denotes a straight-chain alkyl or alkoxy radical having 1 to 16 carbon atoms or a branched alkyl or alkoxy radical having 4 to 16 carbon atoms, it being possible for one or two non-adjacent CH.sub.2 groups to be replaced by a sulfur and/or oxygen atom;A denotes one, two or three aromatic or heteroaromatic rings which are linked to one another directly or via one or two COO groups;B denotes a chemical bond or one or two aromatic or heteroaromatic rings which are linked directly to one another;R.sup.2(a) if B is a chemical bond, denotes an alkyl radical having 2 to 10 carbon atoms which contains an asymmetrical carbon atom which is substituted by CH.sub.3, halogen or a COOC.sub.2 H.sub.

Abstract: Use of compounds or mixtures of compounds which have a chiral, orthogonal, more highly ordered smectic phase in the range of said phase as switching or indicating medium.Compounds which have a chiral, orthogonal, more highly ordered smectic phase, in particular an S.sub.B * or an S.sub.E * phase, can be used in the range of said phase or phases as indicating or switching medium in electro-optical indicating or switching components (devices) which are based on the exploitation of the electroclinic effect.