Patent GB-611706-A (GB)
Title: Improvements in photographic lenticular colour films and methods of treating them
IPC: G03C7/14
Filed: 1940-05-09
Abstract: 611,706. Colour photography. LASSUS ST. GENIES, A. H. J. DE. May 9, 1940, No. 8349. Convention date, June 13, 1939. Addition to 511,804. [Class .98 (ii)] In the method claimed in the parent Specification, wherein at least three emulsion layers are applied to the film in addition to the primary layer, and the additional emulsion layers are screened from the primary layer during production of the primary partial images by an opaque layer or a colour filter or by tinting the primary layer, the additional layer nearest the primary layer is sensitive only to blue and is unaffected by the chemicals used for the developing and colouring of the layers exterior to this layer. In a modification, wherein the method used is that of Specification 526,934, the additional layers being applied to the primary layer after the primary partial images have been formed therein, the additional layer nearest the primary layer is likewise sensitive only to blue and is separated from the remaining additional layers by a filter layer or is itself tinted. As shown, a lenticular film comprises a support F, silver chloride layers 1, 3 and 4, the first being highly transparent, and a blue-sensitive silver bromide layer 2. Layer 1 is blue-sensitive only and is coloured yellow with a water-soluble dye. Layers 3 and 4 are respective green- and redsensitive. A complete primary image is copied in layer 1 using blue light from a lenticular original. After development, the red-selection monochrome component in layer 1 is printed in the layer 4 using suitably directed red rays, and is colour developed. The green-selection monochrome component is similarly printed in the layer 3 and appropriately coloured. The silver chloride in the layers 1, 3 and 4 is dissolved with ammonia. The blue-selection monochrome component is printed in the layer 2 and is developed and appropriately coloured, and the reduced silver and the remaining halide in all the layers is dissolved. In a modification, an intermediate yellow filter layer is provided between the layer 1 and the other layers. In a further modification, the film may have three or four layers, the first layer being a panchromatic bromide layer separated from the other layers by a water-soluble opaque layer, which may comprise two dyes each absorbing one half of the visible spectrum. The colour sensitizers for the layer 1 are also water-soluble. After exposure through a colour filter, the first layer is developed, and then the two layers farthest from the support, which are red- and green-sensitized silver chloride layers respectively, are successively exposed with appropriate rays and coloured. The residual silver chloride is removed by treatment with ammonia. The blue-selection monochrome component is printed in the intermediate silver bromide layer and developed and coloured, and the residual halide and reduced silver is removed. In a further modification, the three layers are coated on the single layer of a lenticular film after the production of the primary black - and - white images therein. Chloride or bromide layers may be used. The layer applied first is blue-sensitive and is coloured yellow or separated from the two others by a yellow filter layer soluble in a sodium thiosulphate bath. The two other layers are successively exposed, developed and coloured. Finally, the filter layer, the residual halide and the reduced silver are removed with Farmer's reducer. In all modifications, the final step is to efface the lenticulations by heat or the application of varnish. The Specification as open to inspection under Sect. 91 refers also to material having a panchromatic silver bromide primary layer, a decolourisable filter layer, and red- and green-sensitized silver chloride emulsion layers. After formation of the primary image in the panchromatic layer and then successive re-exposures to print the red-selection and green-selection component images into the red- and green-sensitized layers, followed by development and colouring, the blue-selection component image is recorded in the originally panchromatic layer (now only blue-sensitive) and is developed and coloured. This subject-matter does not appear in the Specification as accepted.