Electro-optical light control element, for use in display systems e.g. television and computer screens, is operated at a temperature at which the mesogenic control medium is in the isotropic phase

摘要

An electro-optical light control element containing electrodes, element(s) for the polarization of light and a mesogenic control medium is operated at a temperature at which the mesogenic control medium is in the isotropic phase when in its untriggered state. Independent claims are also included for: (1) electro-optical displays containing such light control elements; (2) electro-optical display systems containing one or more such displays; (3) mesogenic control media (especially for use in the above light control elements) containing compounds of formula (I). R1 = 1-7C n-alkyl or n-alkoxy, or 2-7C alkenyl, alkenyloxy, alkynyl or alkynyloxy; A11, A12, A13 = optionally mono-, di- or tri-fluorinated 1,4-phenylene; one of A12 and A13 may be selected from groups such as pyridine-2,5-diyl, pyrimidine-2,5-diyl; A13 may also be of formula (a); A12 may also be 1,4-cyclo-hex(en)ylene, 1,3-dioxan-2,5-diyl, 1,3-oxathiane-2,5-diyl, 1,3-dithiane-2,5-diyl, formula (b) or (c); A11 may also be 1,4-cyclohexylene or 1,3-dioxan-2,5-diyl; Z11, Z12 = single bond, -COO-, -CH=CH-, -CH=CF-, -CF=CH-, -CF=CF-, -CH=CH-COO-, -CF=CF-COO-, -CF=CH-COO-, -CH=CF-COO-, -CF2O-, -OCF2- or -C triple bond C-; X1 = F, OCF3, -CF3, OCF2H, Cl, CN, -C triple bond C-CN or NCS; and n1 = 0 or 1.