Patent GB-369221-A (GB)
Title: Improvements in the manufacture of sound films
IPC: G03B31/00
Filed: 1930-09-04
Abstract: 369,221. Kinematograph films; photo-sensitive layers. SCHINZEL, K., 4, Beethoven Place, Troppau, Silesia, Czecho- Slovakia. Sept. 4, 1930, No. 26448. Convention date, Sept. 4, 1929. [Class 98 (ii).] In making a photographic sound record by electro-optical transfer from a magnetic record, a film is used having a grainless or very finely grained silver halide emulsion layer, which is preferably hyper-sensitized. The finely grained emulsion is such that the size of the grains is of the order of À1 to 5 microns. Hyper-sensitizing is effected by known methods, for example by using ammonia and dissolved silver salts, or by the use of dyes such as erythrosine or pinaflavol. Positive copies may be made on films sensitized by diazo-compounds. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the subjectmatter of Specification 368,852, and, in addition, comprises also the following subjectmatter. An original record may be made on a film " coated with a finest grain negative emulsion, positive emulsion, or little ripened emulsion " which is hyper-sensitized by known methods, by the application of ammonia, and solutions of silver salts. Other emulsions stated to be suitable are silver chloride emulsions sensitized by iodide of pinaflavol, and sensitized silver " haloid " emulsions based on " colludium " or albumen ; erythrosine and pinaverdol are specified as sensitizing agents. For the indirect production of sound-film negatives from these original records, Lippmann emulsions with an increased percentage of silver may be employed. Finest grain " silver haloid " gelatine or " collodium " layers sensitized by iodide of pinaflavol are stated to be suitable, in connection with chemical or physical development, not only for recording sound but also for pictorial work, portraiture, or photo-mechanical reproduction. For making positive copies of sound records by contact or optical printing, using high-power light sources, emulsions entirely without grain may be employed. For example such emulsions may be those produced with diazocompounds developed by ammonia vapour or with " coupling components such as aniline &c. or by alcoholic-alkaline solutions of those materials." Cellophane films impregnated with mercury salts, sensitized by eosin &c. as described in Specification 307,716 may also be used. A reduced copy of a sound record (on which the width of the trace may be .1 to 1 mm.) may be obtained by optically printing an original or an indirectly produced wide negative on to printing paper sensitized by pinaflavol or rhodamine. " Silver haloid salts " to be afterwards sensitized may be produced in known manner by precipitating the component salts in gelatine, collodion, ethyl cellulose, &c., coated on a film base or within the substance of a cellophane film. The sensitized layers or films are provided with a protective coating of gelatine, " protalbine," casein, &c. pervious to the developer. Halation is prevented by dyeing a layer placed between the film base and the sensitive coating, or the protective coating, such red or other dye being easily bleached or washed out ; copying or recording is effected on the back of the film. Two sets of pictures each 24 mm. wide, preferably running in opposite directions, may be made on a film 70-80 mm. wide. Two corresponding sound records may be made in the space between the sets of pictures. The perforations may be in the middle of the film. Pictures produced on a film of this kind may be copied, by optical reduction, on to a fine-grained film of normal size. Grainless or fine-grained negatives made according to the invention may, it is stated, be used " for the manufacture of sound strips by any of the known photo-mechanical methods of graphic reproduction (film collotyping, intaglio printing, &c.)." This subject-matter does not appear in the Specification as accepted.