| 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 polarizability (deltae 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); R1 = -CN, -NCS, -F or -CF3; R2 = R- or RCOO- (R is 1 - 12C alkyl); R3 = R- or RCOO- (R = 1 - 12C alkyl or cycloaliphatic); Z1, Z2(identical or different) = -CC-, -CH2CH2-, -COO- -OOOC- or single bonds; X1, X2(identical or different) = F, Cl or H. R4, R5(identical or different) = R- or RCOO- (R is 1 - 12C alkyl or alkoxy, or 3 - 8C cycloaliphatic ); Z1, Z2(identical or different) = -CC-, -CH2CH2-, -COO-, -OOC- or sinlge bonds; X1, X2 = F, Cl or H; X3, X4 = H or Hal, or R- or RO- (R is 1 - 12C alkyl). R1 = -CN, -NCS, -F or -CF3; R2 = R- or RCOO-(R = 1 - 12C). Z1, Z2(identical or different) = -CC-, -CH2CH2-. -COO-, -OOC- or single bonds; X-1, X2(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 degrees C ; Nematic level deltaTN greater or equal to 50 degrees C ; Positive dielectric anisotropy greater or equal to 8(20 degrees 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 ddeltan = 295 nm). Independent claims are also included for the bistable display apparatus comprising the liquid crystal mixture and use. |
