| abstract |
Cholesteric liquid-crystal mixtures with a small pitch, in which no, or only very little, dependence of selective reflection on temperature is acceptable since a high temperature dependence would disrupt or negate desired effects, are temperature-compensated. Such mixtures are made up of a nematic liquid crystal doped with at least two additives exhibiting chirality which fulfil the following conditions: 1) a(c1B1 + c2B2) = b(c1A1 + c2A2) and 2) 1/ lambda o(T) = a(c1A1 + c2A2) + aT(c1B1 + c2B2) + bT(c1A1 + c2A2) where lambda o is the mean wavelength of the selective-reflection waveband, c1, c2,... are the concentrations of the doping agents exhibiting chirality and Ai, Bi are progression coefficients. |