ELECTRO-OPTICAL LIQUID CRYSTAL SYSTEM

摘要

An electro-optical liquid crystal system of the type P.D.L.C., N.C.A.P. or P.N. comprises a dielectrically positive liquid crystal mixture and another optically transparent medium between two electrodes which may be mounted on substrate plates. The liquid crystal mixture contains one or more compounds of formula (I), where Q<1> is (a), (b) and (c) independently stand for trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluor-1,4-phenylene, 3-fluor-1,4-phenylene and one of A<1> and, if present, A<2> also stands for pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydropyrane-2,5-diyl or naphthalene-2,6-diyl, Z<1> and Z<2> independently stand for a single bond, -CH2CH2-, -COO-, -OCO-, -C=C-, -CH2O- or any combination of these bridge groups, Y and X independently stand for H or F, one of X and Y also stands for Cl, W stands for -CN, -Cl, -F, -CF3, -OCF3, -OCHF2, -NCS or R<2>, R<1> and R<2> independently stand for alkyl with 1 to 12 C atoms in which one or 2 non-neighbouring CH2 groups can also be replaced by -O- or -HC=CH-, and m = 0, 1 or 2.