GB483044A - Improvements in the manufacture of cinematograph films - Google Patents

Abstract

483,044. Photo - mechanical printing of picture and sound films. ARMSTRONG, J. J. V. Oct. 7, 1936, Nos. 27209 and 29449. [Class 98 (ii)] Kinematograph films bearing pictures with or without sound tracks or sound tracks alone are produced by printing from an original record on transparent material onto a lightsensitive layer on a metallic strip without the use of any photo-mechanical screen or graining and forming depressions on the metallic strip corresponding in area to the silver image on the original and in depth to the tones of the original viewed as a transparency, the images being then inked and used to print onto a receptive surface. Instead of printing directly onto the metallic strip a separate light-sensitive layer, e.g. a bichromated colloid layer may be used and subsequently transferred to the surface of the metallic strip. The receptive surface may be a cellulose acetate strip, the printing ink then containing a solvent for cellulose acetate, e.g. acetone. For variable density sound tracks a semi-transparent ink is used and for variable area tracks an opaque ink. The metallic strip may be of copper and may be coated with a mixture of colloids such as fish glue and gelatin, or a known cold enamel as used for line blocks may be employed. Paper may also be used as the receptive surface. According to the first Provisional Specification, coloured kinematograph films may be produced by successive printings from ribbons of zinc or other metal each bearing sets of spaced parallel lines of resist coated under or over the light-sensitive layer, the records corresponding to one of the colours of a multicolour screen record being printed on the layer on each ribbon and the ribbon etched. One of the ribbons may carry a sound track preferably wholly unscreened. Registration may be effected by placing opposite each picture a dot or pair of dots and employing a photoelectric cell in circuit with electromagnetic means for displacing the film if the dot or dots are out of register with the cell. In a modification, negatives made by interposing ruled screens having spaced parallel lines may be used to print on the sensitized strips. According to the second Provisional Specification the printing may be effected by offset and the receptive surface may be of the material known under the Registered Trade Mark " Cellophane." Specification 422,180 is referred to.