US2490442A - Process for obtaining the subtitles of kinematograph films - Google Patents

Description

Dec. 5, 1949 KAGANSKY 2,490,442

PROCESS FOR OBTAINING THE SUBTITLES OF KINEMATOGRAPH FILMS Filed Jan. 15, 1947 a) M M Patented Dec. 6, 1949 PROCESS FOR OBTAINING THE SUBTITLES OF KINEMATOGRAPH FILMS Nachoum Kagansky, Paris, France Application January 15, 1947, Serial No. 722,193 In France January 22, 1946 1 Claim.

The invention relates to the process for obtaining the sub-titles of kinematograph films which comprises forming on the film an acidproof resist (for example a layer of parafiln), eliminating the resist along the contour of the letters of the sub-titles by effecting an impression by means of typographic characters, preferably in the hot state, dissolving the silver of the emulsion layer at the places which have been exposed by the impression, and finally eliminating the resist.

The invention relates more particularly to dissolving the silver and aims at obtaining absolute transparency of the sub-titles by an operation of minimum duration.

In carrying out the above referred process, the silver is dissolved by placing the emulsion in contact with a nitric acid solution and the film is then Washed. However, experience shows that it is difiicult to eliminate completely the silver nitrate produced. This residual silver nitrate is decomposed by light and becomes yellow or black, so that the sub-titles, instead of being a pure white contrasting with the picture background, are yellowish, of faulty appearance and sometimes difiicult to read.

It would be possible to treat the silver with hydrochloric acid and dissolve the silver chloride in sodium thiosulfate, but the conversion of the silver into silver chloride is too slow to enable a practical application of this process to be effected in a machine having an output which is acceptable from an industrial standpoint.

The process following the invention permits to obviate these difficulties by successively subjecting the silver of the emulsion to the action of a nitric acid solution, to the action of a hydrochloric acid solution, to washing with water, to fixing with sodium thiosulfate and finally to a final washing.

By operating in this manner the output of the machine is satisfactory and the quality of the sub-titles is substantially improved.

The accompanying drawing shows, by Way of example, a diagrammatic arrangement for the application of the invention.

In this drawing, A designates the film to be provided with sub-titles, which has previously been coated with parafi'in or other resist substance, in which the sub-titles have been printed by means of typographic characters, preferably in the hot state in order to facilitate the expulsion of the paraffin. Said film passes with a speed of 5 metres per minute over guide rollers I, 2, 3, 4, 5,

6, l, 8 and cylinders 9, H! and l l, the cylinders 9 and Ill being partly immersed in a tank l2 containing a solution of fuming nitric acid at room temperature, and the cylinder H in a tank l3 containing a 60 Baum hydrochloric acid solution. Free rollers l4, l5, placed in the loops of the film give it the requisite tension.

The thickness of the cylinders 9, I0 and H is equal to or slightly smaller than the width of the film between perforations, and as they rotate, said cylinders bring the reagents into contact with the emulsion face of the film. The nitric acid attacks the silver of the emulsion and the silver nitrate dissolves in the nitric acid of the tank 12. The nitrate which may remain adhering is then converted into chloride in the tank l3.

Jets of washing water are projected on to the loop of the film passing round the roller l5, as shown diagrammatically at [6. The film then passes into a sodium thiosulfate fixing bath, in which the residual silver chloride is dissolved, then into a final bath of washing water. The sub-titles thus obtained are absolutely transparent.

Of course, the invention is not limited to the practical details hereinbefore described which have only been given by way of example.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

A process for obtaining the sub-titles of kinematograph films, which comprises forming on the emulsion layer of the film an acid-proof resist, eliminating the resist along the contour of the letters of the sub-titles by an impression by means of typographic characters, successively treating the silver of the emulsion layer first with nitric acid and then with hydrochloric acid separately, washing, fixing with sodium thiosulfate, washing again, and finally eliminating the resist.

NACHOUM KAGANSKY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,649,621 Slocum Nov. 15, 1927 1,704,124 Fiedler Mar. 5, 1929 1,861,827 Titus June 7, 1932 2,051,603 Hruska Aug. 18, 1936 2,152,306 Grebe Mar. 28, 1939

Images