GB563298A - Improvements in or relating to endless film winding devices for motion picture projectors - Google Patents

Abstract

563,298. Kinematograph projectors. DEHN, F. B. (Mills Novelty Co.). Jan. 27, 1943, No. 1398. [Class 97 (i)] In an endless film winding device for kinematograph projectors, of the type in which an endless coil of film is rotatably mounted and a portion of it is formed into an outside loop which is threaded through the projector, the innermost convolution of the coil being fed out by a power - operable drive element, the drive element directs the film at an angle into the loop and is driven from a source of uniform power through a variable-speed gearing which is controlled through a brake by means engaging the film in the loop, so that the rate of winding is determined by the size of the loop. As shown, the endless film coil 33 is mounted on a circular series of anti-friction rollers 32 carried by a frame member 31. An external loop is formed by a part of the film extending from the innermost convolution outwardly at an angle to the plane of the coil and passing round a drive sprocket 41, through the flin-feeding means and gate of the projector, through an automatic switch 27 which stops the projector on breakage of the film, then through a sound reproducer 13, and thence to the outer convolution of the coil. The sprocket 41 is mounted on ball-bearings on an adjustable sleeve 56, and rotates in a plane inclined to that of the film coil. It is driven through an internal gear 47 and gear 54 from a shaft 42 carrying a disc 71 on which are mounted the planetary wheels 66 of an epicyclic gearing, these wheels engaging a central gear 68 and an internal ring gear 69. The gear 69 is secured to a pulley 73 rotated by the projector, as shown, or other power source, and the gear 47 is secured to a brake drum 76 acted on by a brake 85 operated by a pivoted arm 81 carrying a friction roller 83 which engages the film loop. The brake is automatically adjusted by the action of the loop on the arm 41 to allow sufficient rotation of the gear 68 to reduce the effective ratio of the epicyclic train to a value at which the sprocket 41 pays out the film at the correct speed, thus maintaining a loop of constant size. The arm 81 operates the brake through a spring member providing a lag in operation which prevents excess stressing of the film in the loop, and is spring-loaded to assist the application of the brake by the film.