Liquid crystal coated panels sensitive to tem - peratures or electric fields

摘要

The panels are prepared by applying a solution of liquid crystals (preferably esters of cholesterin for temp. detection; nematic substances, pref. p,p'-disubstituted benzylidene-anilines for electrical phenomena) to a carrier (any organic high-polymer, metal or paper) with a roughened surface (by sand blasting embossing or application of a filler together with a binder and/or a suitable high-polymer) to fill up about 1/3 to 1/2 the pack height and coating the panel after drying with a suitable protective layer, which is firmly fixed to the carrier/crystal layer by the roughness. The carrier is pref. 0.03-0.2mm thick, the crystal layer 0.01-0.05 mm and the protective coating 0.02-0.1mm. The crystal layer is protected against contamination and the panel can be reused. There is no tendency for the protective coating to slip. Panels are used to detect heat evolution or conduction (for this the coating or the carrier contains a dark pigment for easier detection of the change) or potentials or are used as image screen material.