Supertwist LCD with very short total switching time and high contrast - suitable for lap top display and liq. crystal mixt. contg. di:halo-methenyl cyclobutane cpd. etc.

摘要

Supertwist LCD has 2 plane parallel plates with a border forming a cell, filled with a nematic liq. crystal (LC) mixt. with positive dielectric anisotropy and electrode films and superimposed orientation films on the inside of the plates. Surface tilt angle of the long axis of the mols. is 1-30 deg. and the twist of the mixt. 100-600 deg. LC mixt. is based on component A, contg. comprises dihalomethenyl-cyclobutane cpd(s). (IIa), benzonitrile cpd(s). (IIb) and/or (IIc) and opt. other benzene or phenylethane cpds. of formulae (IId-f) and contains 40 (wt.%) LC component B of cpd(s). with a dielectric anisotropy of -1.5 to +1.5 of formula (I), 0-20% LC component C of cpd(s). with a dielectric anisotropy under -1.5 and an optically active component D in an amt. giving a ratio of ca. 0.2-1.3 between the film thickness and the natural pitch of the chiral nematic LC mixt. In the formulae R is 1-9C n-alk(en)yl or alkoxy; rings A and B are 1,4-cyclohexylene (Cyc), 1,4-phenylene (Phe), 2-fluoro-1,4-phenylene (2F-Phe), 2,6-difluoro-1,4-phenylene (2F,6F-Phe), pyrimidin-2,5-diyl (Pym) or 1,3-dioxan-2,5-diyl (Dio); L is H or F, L1-2 is F or Cl, Z is -CH2CH2, -COO- or a singlehard, X is F, Cl, -CF3-CHF2, -OCF3, -OCHF2, -OCF2CF2H, or -OC2F5, n is 0, 1 or 2. ADVANTAGE - Short switching times and good contrast and angle dependence.