Liquid nematic crystal mixtures for liquid crystal display systems of bistable visualisation of bill posters

摘要

Mixtures of nematic crystals for bistable displays with a low energy of anchorage. Nematic liquid crystal mixtures for bistable displays comprises: (a) at least 40 % wt. of compounds of high molecular polarisability(delta e greater than 10) and high dipole moment(psi greater than 1 D) but with a low zenithal anchorage of formulae (AI) - (AIV); (b) 0 - 60 % of compounds of low anchorage of formulae (BI), (BII), (EI), (EII), (FI) and (FII); (c) 0 - 25 % of compounds comprising dipoles, from compounds of formulae (CI) and (CII); (d) 0 - 10 % of a compound of formula (D); (a) [Image] R 1-CN, -NCS, -F or -CF 3; R 2R- or RCOO- (R is 1 - 12C alkyl); R 3R- or RCOO- (R = 1 - 12C alkyl or cycloaliphatic); Z 1, Z 2(identical or different) : -CC-, -CH 2CH 2-, -COO- -OOOC- or single bonds; X 1, X 2(identical or different) : F, Cl or H. [Image] R 4, R 5(identical or different) : R- or RCOO- (R is 1 - 12C alkyl or alkoxy, or 3 - 8C cycloaliphatic ); Z 1, Z 2(identical or different) : -CC-, -CH 2CH 2-, -COO-, -OOC- or sinlge bonds; X 1, X 2F, Cl or H; X 3, X 4H or Hal, or R- or RO- (R is 1 - 12C alkyl). [Image] [Image] R 1-CN, -NCS, -F or -CF 3; R 2R- or RCOO-(R = 1 - 12C). Z 1, Z 2(identical or different) : -CC-, -CH 2CH 2-. -COO-, -OOC- or single bonds; X-1, X 2(identical or different) : F, Cl or H. The mixtures have the following physical characteristics :- Nematic transition temperature-liquid isotrope (TN-1) greater or equal to +50 [deg] C ; Nematic level delta TN greater or equal to 50 [deg] C ; Positive dielectric anisotropy greater or equal to 8(20 [deg] C) ; Low zenithal anchorage on at least one of the plates of the bistable display(characterized by a breakdown voltage, Ulambda /2 less than 25 volts, for a cell of thickness d such that ddelta n = 295 nm). Independent claims are also included for the bistable display apparatus comprising the liquid crystal mixture and use.