Patent GB-518213-A (GB)
Title: Photographic printing process for images on multilayer material
IPC: G03C7/00
Filed: 1938-06-13
Abstract: 518,213. Luminescent materials and applications thereof. GASPAR, B. June 13, 1938. No. 17488. [Class 39 (i)] [Also in Group XX] The part-images of a composite picture comprising two superposed part-images and a fluorescent substance are separated by exposure to rays causing the fluorescent substance to emit light of a different spectral composition and separately reproducing the part-images on a screen or light-sensitive layer by the fluorescent rays. The fluorescent substance may be incorporated in the image-bearing layers either before or after exposure. After developing and fixing the film may be impregnated with a solution of a coloured or uncoloured substance fluorescing on exposure to ultra-violet or visible light. The material may be exposed from both sides to the fluorescent-producing light or the two layers may be successively exposed to the same light. A filter absorbing either the primary or secondary light or both may be arranged between the two layers and the light source and the printing material are arranged on the same side of the image to be printed. Water-soluble or insoluble filter dyes may be used. The filter dye or the fluorescent substance may be produced after exposure from a dye-forming substance present in the taking material. A bipack comprising a front film carrying a blue-sensitive emulsion and a rear film carrying a front green-sensitive emulsion, a red filter layer, and a rear redsensitive layer may be employed. A red filter dye may be Para Red incorporated in the form of its insoluble bisulphite compound. The part images may be dye images instead of silver images. The fluorescent material may be incorporated in a separate layer between the image-bearing layers, for example, in the support. As shown, the original film comprises two image-bearing layers 2, 3, with an intermediate layer 1 containing Rhodamine. The layer 1 may be the support or the three layers may be carried on a support. The two sets of dyeimages A, B are formed by the red dye Supranol Brilliant Red B. Light from the source 4 strikes the layer 3 and the images B are printed on the film 6. Light from the source 7 strikes the layer 2 and the images A are printed on the film 9. Green filters 5 and 8 may be inserted between the light sources and the original film, and red filters may be placed between the original and copy films. Light sources emitting rays for which the copy films are insensitive may be employed. A composite image formed by superposing two different images formed by the same magenta dye with the interposition of a Rhodamine-containing gelatine foil may be printed by a mercury lamp provided with a green filter, a red filter being placed between the composite image and the panchromatic printing layer. Exposed silver halide emulsions processed to form the silver images are uniformly dyed with Polarbrillantred 3B, treated successively with solutions of diphenyl guanidine acetate and of chromium alum and dried. The dyed images are treated with a solution of hydrochloric acid, potassium iodide and 2 : 3- diamino-Phenazine to locally destroy the dye and the remaining silver is bleached by acid cupric chloride and removed by hypo. The taking material may have silver halide' emulsions sensitized to red and green respectively on opposite sides of the support, the fluorescent layer being separated from the superposed emulsion layer by a thin hardened gelatine layer. The film may be used as the rear element of a bipack, the front element of which has a blue-sensitive, emulsion layer. The two original images may be dyed blue-green with Xylene Blue V. Scoric or triorindine B supra, the light employed being a cadmium lamp in conjunction with a green filter, a red filter being placed between the original and the printing material. The rear image is printed in this arrangement by the fluorescent light. The blue-green images may be produced by bleaching the silver images and dyeing. Other fluorescent substances are fluorescein auramine and acridine salts. The dye images may be formed by dyeing gelatine reliefs, forming relief images in predyed layers, colour development, mordenting, dye-toning or dye-destruction. A Rontgen-ray tube may replace the light source. The part-images may, instead of being photographically printed, be viewed directly, projected on a projection screen or on to the light-responsive device of television apparatus. The part images may be stereoscopic and the "dyes" may be practically colourless and absorb light outside the visible spectrum only. Specification 496,559, [Group XX], is referred to.