Abstract: A metal dithiene of the formula: ##STR1## wherein R.sup.1 is C.sub.3 to C.sub.20 alkyl;R.sup.2 is selected from alkyl, alkylamino, dialkylamino, alkylthio and alkoxy in which each alkyl contains up to 20 carbon atoms;R.sup.3 is H, halogen or a group represented by R.sup.2 ; andM is a metal selected from Groups Ib, IIb, VIIb, and VIIIb of the Periodic Table,and a composition of the metal dithiene in a liquid crystal medium. The composition is suitable for use in a light valve for a laser-addressed liquid crystal display.

Abstract: A metal dithiene of the formula: ##STR1## wherein R.sup.1 is C.sub.3 to C.sub.20 alkyl;R.sup.2 is selected from alkyl, alkylamino, dialkylamino, alkylthio and alkoxy in which each alkyl contains up to 20 carbon atoms;R.sup.3 is H, halogen or a group represented by R.sup.2 ;and M is a metal selected from Groups Ib, IIb, VIIb, and VIIIb of the Periodic Table,and a composition of the metal dithiene in a liquid crystal medium. The composition is suitable for use in a light valve for a laser-addressed liquid crystal display.

Abstract: A liquid crystal display includes a liquid crystal cell formed by enclosing a thin layer of a cholesteric liquid crystal material between two slides. A set of electrode structures is formed on each slide so that voltages may be applied to the liquid crystal material causing an observable display effect. Voltages are supplied to the electrodes in sequence by driver electronics under the control of a logic unit which also controls a variable voltage source supplying voltages to the driver electronics. The logic unit controls the drive electronics to give an R.M.S. voltage V.sub.x at elements required to be at an OFF state and an R.M.S. voltage V.sub.c higher than V.sub.x at elements required to be in an ON state. The logic unit also controls the voltage source to reduce its voltage output to both OFF and ON elements simultaneously while maintaining the ratio of V.sub.x and V.sub.c for a period while information displayed is to be changed.