Nematic liquid crystal medium for use in electro-optical displays contains dielectrically positive compounds, dielectrically negative compounds and optionally dielectrically neutral compounds

摘要

Nematic liquid crystal (LC) medium containing dielectrically positive compound(s), dielectrically negative compound(s) and optionally dielectrically neutral compound(s). Nematic LC medium containing (a) dielectrically positive compound(s) of formula (I), (b) dielectrically negative compound(s) (II) and optionally (c) dielectrically neutral compound(s) (III): R1, R21, R22, R31, R32 = 1-7C alkyl or alkoxy, or 2-7C alkoxyalkyl, alkenyl or alkenyloxy; Z11, Z12, Z13, Z21, Z22 = -CH2CH2-, -CH=CH-, -C equivalent to C-, -COO- or a single bond; Z31-Z33 = -CH2CH2-, -CH2O-, -OCH2-, -CF2O-, -OCF2-, -COO- or a single bond, and one of these may also = -CF2CF2-; A11-A13 = trans-1,4-cyclohexylene (Cyc), 1,3-dioxan-2,5-diyl (Diox), 1,4-phenylene (Phe), 3-fluoro-Phe (3FP) or 3,5-difluoro-Phe (35DFP); A21, A22 = Cyc, Phe, 3FP, 2,3-difluoro-Phe (23DFP), pyridine-5,2-diyl (52PDL) or pyrimidine-5,2-diyl (PMDL); A31-A34 = Cyc, Phe, 3FP, 5-fluoro-Phe (5FP), 52PDL, pyridine-2,5-diyl (25PDL), Diox or PMDL; X = F, OCF2H or OCF3; Y = F if X = F or OCF2H, or Y = H or F if X = OCF3; L1 = L2 = C-F, or one of these is N and the other is C-F; n, m, l, o, p = 0 or 1 An Independent claim is also included for electro-optical displays containing an LC medium as defined, preferably active matrix displays with 3-pole active switches.