GB518971A - Improvements in or relating to means for feeding sound record and other films - Google Patents

Abstract

518,971. Cinematograph apparatus. TOBISTONBILD SYNDIKAT AKT.-GES. Sept. 5, 1938, No: 25965. Convention date; Sept. 3; 1937. [Classes 97 (i) and 98 (ii)] Apparatus for feeding a sound record or other film 7 comprises a smooth feeding roller 3 cooperating with a pressure roller 4 and located between two sprockets 8, 9 spaced from it sufficiently to enable the film to form a free loop between each sprocket and the roller. The loops by change of their form alter.the curvature of the film around the feeding roller and thereby automatically maintain a constant rate of feed, which is independent of any shrinkage of the film, and the provision of loops in front of and behind the feed roller substantially balances the forces due to them so that only light pressure is necessary for feeding the film. In the film carrying apparatus shown, a negative film 1 is fed over the roller 3 by sprockets 2, 6, and is tensioned by a movable roller 5. The negative film 7 is driven by contact with the negative film, and according to the varying shrinkage which has occurred in the latter the loops iri the film 7 take up forms represented by the dotted, full, and chain-dotted lines. Thus, when the shrinkage is great, the film 1 drives the film 7 more slowly, so that the loop between the roller 3 and sprocket 8 increases and the film 7 takes the chain-line form with a convex curvature to the feed roller, causing it to be driven at a higher speed relatively to the film 1. When the shrinkage of the film 1 is less it tends to drive the film 7 at greater speed, which causes the latter to take a form such as that shown in full or dotted lines, which is less concave or is convex towards the feed roller, so that it is driven at a lower speed relatively to the film 1. The speed of the film 7 is thus maintained constant irrespective of variations in the speed of the film 1 due to variable shrinkage in it Guides 10 for the loops and indications showing the shape of the loop to be formed when inserting the film, may be provided.