Patent ID: 7029731

Claim:
A liquid-crystalline medium comprising a mixture of polar compounds having positive dielectric anisotropy, wherein said mixture comprises one or more compounds of formula I, in which R is H, an alkyl or alkenyl radical having 1 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, it also being possible for one or more CH 2 groups in these radicals to be replaced, in each case independently of one another by —O— —CO—, —CO—O—, —O—CO—, —S— or —O—CO—O— in such a way that O atoms are not linked directly to one another, A 1 (a) is a trans-1,4-cyclohexylene radical in which one CH 2 group is replaced by —O— or —S—, where the radical (a) may be monosubstituted or polysubstituted by CN, CH 3 or F, Z 1 is —CO—O—, —O—CO—, —CH 2 —O—, —OCH 2 —, —CH 2 CH 2 —, —CF 2 O—, —OCF 2 —, —CH═CH—, —C≡C—, —(CH 2 ) 4 —, —CH═CH—CH 2 CH 2 — or a single bond, Y is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having 1 to 6 carbon atoms, L is H or F, and m is 1.