Super-twist liq. crystal displays having wide working temp. range - contain nematic liq. crystal mixt. with specified range of properties

摘要

In a super-twist liq. crystal display with (a) two plane-parallel supporting plates forming, with a border, a cell, (b) contained in the cell, a nematic liq. crystal mixt. (I) having positive dielectric anisotropy to which a doping component consisting of one or more dopants is added, (c) electrode layers with orientation layers laying on top on inner faces of the supporting plates, (d) an angle between longitudinal axis of mol. at surface of supporting plates and the supporting plates of about 1-30 deg., and (e) twist angle of liq. crystal layer in cell from orientation layer to orientation layer of between 160 and 360 deg., (I) has clear pt. of 70 deg.C or more, and, in temp. range 0-50 deg.C, low temp. dependence of dielectric anisotropy, d delta epsilon/dT being less than 8 x 10 power (-2) K, and negative temp. dependence of helical twisting power (HTP), of dopant(s), d(HTP)/dT being between zero and -5 x 10 power (-2) mu-m-1 K-1. ADVANTAGE - Displays have wide working temp. range for external uses such as portable computers or displays for motor vehicles, favourable contrast, angle dependence of contrast, stability, switching time, etc..