Patent GB-626727-A (GB)
Title: Improvements in or relating to the recording of sound tracks in colour film
IPC: G03C7/22
Filed: 1946-11-29
Abstract: 626,727. Photographic colour picture and sound films. HARRISON, G. B., and ILFORD, Ltd. Nov. 29, 1946, No. 35490. [Class 98 (ii)] Into a multilayer film comprising a support carrying three silver halide emulsion layers selectively sensitive to red, green and blue light and separated by barrier layers, and which film is developed by reversal, preferably with the colour-formers in the developing solutions; a negative sound track is recorded (by direct exposure or by printing) and developed in one, two or all three of the emulsion layers, and thereafter, as a step prior to, subsequent to, or intermediate between the steps of colour developing picture images in the material, the sound track area only of the film is re-exposed to form a reversed image in one, two or all three emulsion layers and the reversed images are colour-developed to form positive sound track images in coloured dyestuff, the sound track images thus formed, or at least one of them, being a colour different from the colour of the dyestuff used for the picture area of the layer in which the sound track is located Using a film in which the barrier layers are, preferably, ones of the type containing colloidal silver sulphide together with a very small amount of silver halide as particularly described and claimed in Specification 595,582, eleven different reversal re-exposure and colour development procedures are specified, all of them requiring separate re-exposures for the sound track area and the picture area of the film with light of various colours, and resulting in finished films with sound tracks such as ones of cyan or magenta dye in the original blue-sensitive layer, of cyan dye in all the layers and other combinations. In a specific example a film having (a) transparent support, (b) gelatino silver iodobromide emulsion red sensitized with 2.2<SP>1</SP>.8 - triethyl - 4.4<SP>1</SP> - dichloro - thiocarbocyanine bromide, (c) gelatine layer containing colloidal silver sulphide and silver halide, (d) gelatino silver iodobromide emulsion green-sensitized by 1.1<SP>1</SP>-diethyl-pseudocyanine iodide, (e) layer as (c) but containing the dyestuff .1-b-sulphophenyl - 3 -methyl - 4 - cinnamylidene - -pyrazole - 5 - one, and (f) blue-sensitive gelatino silver iodobromide emulsion ; is exposed on layer (f) to a coloured object and the sound area exposed to record by blue light a negative sound record; developed in a metol-quinol developed to produce negative silver records in the picture areas, a yellow-brown deposit in layers (c) and (e) and to bleach the dyestuff in (e) ; washed, exposed on the picture area only of layer (f) with blue light and developed in a 2.4-chloracetoanilide colour developer; exposed on the picture area only of layer (b) and the sound track area only of layer (f) with blue light and developed in a 2.4-dichlor-α-naphthol colour developer; exposed on the picture area only of the middle layer (d) from both sides with ultraviolet rays and developed in a 1-p-nitrophenyl- 3-methyl-5-pyrazolone colour developer; fixed and bleached in Farmer's reducer, to produce a full colour image of the original object as well as a cyan dye sound track image in layer (f). Specification 528,433 also is referred to.