Colour luminescent screen prodn - using complexing agent in sensitive material for improved raster edges

摘要

Luminescent screen for colour picture CRTs is produced by applying several raster layers using radiation-sensitive layers which change their solubility in a solvent when partly exposed through a mask and are sensitised by the addn. of bichromate. The material also contains a complexing agent, which complexes part of the Cr(III) formed on exposure and thus regulates the amt. of Cr(III) entering into a cross-linking reaction with the sensitive material. The method is used in the prodn. of screens with phosphor elements having a a smaller area than the apertures in the mask used. The boundary edges of the raster layers are more uniform and accurate. Pref. the sensitive material (I) is PVA the sensitiser (NH4)2Cr2O7 in an amt. of 0.01-0.5 (0.03-0.1) g/g (I) and the complexing agent the di-Na salt of EDTA in an amt. of 0.005-0.5 (0.01-0.03) g/g (I). The pH is adjusted to the optimum for the complexing agent.