Patent GB-432464-A (GB)
Title: An improved method for the production of combined sound and kinematograph films
IPC: G03C7/00
Filed: 1934-06-23
Abstract: 432,464. Kinematograph picture films. GASPAR, B., 38, Innsbruckerstrasse, Schoneberg, Berlin. June 23, 1934, No. 18636. [Class 98 (ii)] [See also Group XXXVIII] In the production of combined coloured sound and picture film records, the metal deposit images (both sound record and pictures) are produced in one or more layers of a single or multi-layer photographic material which has colour-forming substances incorporated in the said layer or layers, either prior to or subsequently to the formation of the metallic images, the layer(s) being afterwards so treated as to produce a coloured sound record and coloured pictures at the metal image or non- image points. The colour-forming substances used comprise any substance which, when incorporated in the photographic layer, is capable of being converted by oxidation, reduction, diazotization, &c., into a dyestuff or pigment, and which permits of selective destruction of the colour in the required manner ; they may also include a substance which is itself coloured, but which is convertible into a dye of a different colour to form the finished sound image. Various methods of carrying out the invention are described. For example, the dyestuffforming substance may be converted by a developer into a dyestuff, at the points of the developed silver, in the manner described in Specification 2562/13, [Class 98 (ii)]. By this method, a blue image may be produced in a layer containing alpha - naphthol, using a developer containing diethylparaphenylenediaminechlorohydrate, followed by the use of Farmer's reducer to remove the silver. Or the oxidation method described in Specification 379,679 may be used. Preferably, however, a method is employed in which the formation of the dyestuff is independent of the silver image, the latter being effective only for the selective destruction of the dyestuff or the dyestuff-forming substance, and several examples are given. For instance, zinc ferricyanide, diffusely incorporated in a photographic layer preferably before the formation of the metallic sound and picture images, is developed by ferrous oxalate. A Prussian blue colour is formed, and is subsequently converted into reversed sound and picture images by a bath containing thiocarbamide and hydrochloric acid. Nickel dimethylglyoxin or zinc chromate may alternatively be used for producing red and yellow images respectively. A leuco-base, which is subsequently oxidized to form the dyestuff, may be incorporated in the layer as a finely divided deposit, a salt of phosphotungstic acid, molybdic acid, or tannic acid. The diffusely formed dyestuff is then destroyed at the image or non-image portions, e.g. as described in Specifications 395,718, 397,159, 397,188, and 397,192 ; or the dyestuffforming substance may be first destroyed locally in a manner depending upon the metallic images, and the remainder may then be converted into the dyestuff by further treatment. The oxidation of the leuco-base and the selective destruction of the dyestuff may also be effected in a single bath containing, e.g. permanganate of potash and hydrochloric acid. In carrying out the invention, the photographic characteristic of the sound image may be modified as desired, by varying the exposure, the time of development, the concentration of the dyestuffforming substances, or the time during which the dyestuff-destroying agent acts. Preferably, a multi-layer material is used, the individual layers being sensitized for different colours, so that each component colour image may be printed into the appropriate layer by suitably coloured light. The sound image may be located in any one of the layers, and its colour may be specially adapted to the sensitivity of any particular kind of photo-electric cell used in reproduction ; or the image may be in more than one of the layers, the colours of which may be chosen to form a subtractive black. In the case of a variable-density sound record, the image is preferably restricted to one layer, the dyestuff-forming substances in the other layers or the dyestuffs formed therefrom being destroyed if necessary. The reagents used to perform the selective destruction of the dyestuffforming substances &c., should preferably also bleach out the silver image ; otherwise the silver should be bleached out by a reagent such as an acidified solution of copper chloride. Specifications 412,949, 413,688, [both in Group XXXVIII], 416,566, 416,660, and 416,666 also are referred to.