| 摘要 |
1,030,218. Photographic processes using photochromic materials. NATIONAL CASH REGISTER CO. Dec. 21, 1964 [Feb. 4, 1964], No. 51793/64. Heading G2C. Silver images are produced by imagewise exposing a layer of one or more non-crystalline spiropyran compounds to ultra-violet, treating the imaged layer with hydrogen halide vapour until a yellow acid complex is formed (Specification 1, 030, 217), allowing the acid vapours to evaporate from the background areas, coating the layer with an aqueous solution of silver nitrate to form a silver halide image and then reducing this image to a silver image. The photochromic layer may be binder-free but preferably contains a cellulose ester or ether and is preferably coated on a glass or polyester support. After exposure, the layer may be treated with sulphur dioxide vapour before exposure to halide vapours, and after the formation of the silver halide image, the layer may be treated with ethyl alcohol to remove the unused silver nitrate. The silver halide is reduced to a silver image by using a photographic developer.
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