Patent GB-519831-A (GB)
Title: Improvements in and relating to processes and apparatus for making matrices and for printing multi-coloured pictures
IPC: G03C7/22
Filed: 1938-09-27
Abstract: 519,831. Photographic imbibition and bichromated colloid printing. RONCAROLO, E. Sept. 27, 1938, No. 28143. Convention date, Sept. 28, 1937. [Class 98 (ii)] In a machine for printing dye - impression multi-colour films, the matrix and reception films are registered by a number of elements each having the shape and size of one picture field and provided with four teeth to engage the corner feed perforations of a picture field of both films. In a modified machine, each element has the shape and size of two or more picture fields, and is provided with a set of four teeth for each field. Windows may be provided in the elements to permit the machine to be used for printing bichromated-colloid films As shown in Fig 1 the machine comprises a fixed guideway 17 having rollers. 18 supporting the bight of an endless chain of hinged registering elements 16, each provided with four teeth as described above, the chain being mounted on driving wheels 14, 15. Above the guideway 17 is a pressure member 27 having rollers 28 below which an endless belt 26 mounted on rollers 29, 30 and comprising two bands pressed apart by interposed springs 26<1>, Fig. 5, the bands being perforated to permit the passage of the registering teeth on the elements 16. The matrix film 19 after passing through a dye bath 24 meets the reception film 20 at a roller 25 which guides the two films on to the registering teeth, whereafter they pass under the pressure member 27 and band 26 to effect the impression, and are led away separately over guide rollers. In the modification shown in Fig. 2, elements 116 for registering several pictures at a time as described above are mounted at their middles on a metal conveyer band 35. To adapt the machine for bichromated - colloid printing, windows are provided in he elements, the rollers 18 on the guideway 17 are replaced by ball bearings, and a light source such as a mercury-vapour lamp is placed below the guideway 17. The Specification as open to inspection under Sect. 91 describes alsd methods of and printing apparatus for producing the relief printing matrices. The monochromatic negatives, produced by the silver bromide process, are themselves converted into the matrices by immersion in a bichromate bath drying, and exposing to light through the support to render insoluble the parts of the gelatin which are free from silver. The image-bearing parts are then removed by swelling in cold water, elimating the silver as with " Farman's liquid," and then dissolving away the gelatin with hot water. The relief matrix so produced is immersed in a bath of water and glycerine to maintain it moist, and after hardening in a chrome alum or formalin bath is ready for printing. The height of the relief may be increased by applying a gelatin coating to the negative before sensitizing it with bichromate. To produce a reversed matrix, a layer of bichromated gelatin may be applied to the back of the negative and exposed to light through the negative, subsequent procedure being the same as before. Apparatus for exposing the film through its support comprises a casing 4, Fig. 1 (Cancelled), having a dark chamber enclosing supply and take-up spools 2, 3. The film is guided by rollers, one 12 of which is driven, across a recess 6 in front of the casing, where it is exposed to a light source in a casing 11. In a modified apparatus, the film passes over a rotatable drum having a white surface and filling the gap 6 in the front of the casing, the light source in this case being concave to conform to the outline of the drum. This subjectmatter does not appear in the Specification as accepted.