GB576752A - Improvements in or relating to the projection of photographic films and to the exposure of such films - Google Patents

Abstract

576,752. Film projectors and cameras. NEWTON & CO., Ltd., and HAKES, R. W. April 11, 1944, No. 6615. [Classes 97 (i) and 98 (i)] In means for feeding a film in a projector or camera a driving shaft rotates through a pin and slot lost motion device a feed roller mounted on it, and during the initial lost motion period operates a cam frictionallyengaging it, so causing the cam to release film-clamping means prior to the operation of the feed roller. In the device shown; for moving a strip film frame by frame through a projector, the film is moved between containers 2 and 3 and through the projection gate by a sprocket roller 7 loosely mounted on a shaft operated by a knob 6 and carrying a pin engaging a circumferential slot 11 in the roller, which is thus rotated after an initial degree of rotation of the shaft has occurred. During this initial rotation the shaft gives a limited angular movement to a cam 13 through spring friction clutch 17, the cam engaging a pin 26 on one arm of a pivoted inverted U form lever 25, thereby swinging it to the left, as seen in Fig. 3. The arms of this lever are each formed with a slot in which engages a lug 19, 20 extending laterally from the frame of a glass pressure plate 18, which is thus moved, against the action of the blade springs 23, 24, to unclamp the film. The cam 13 is of double form, so that the apparatus is operative for either direction of movement of the film.