GB382860A - Improvements in or relating to film-handling or -propelling apparatus - Google Patents

Abstract

382,860. Film-driving mechanism. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.- (Assignees of Reynolds, E. W. ; 4028, Sommers Avenue, Drexel Hill, Pennsylvania, U.S.A.) March 14, 1932, No. 7555. Convention date, April 17, 1931. [Class 40 (ii).] A film-driving mechanism particularly applicable to sound-recording or reproducing apparatus, comprises a pair of sprocket wheels and a pair of film-driven inertia rollers, one of the sprocket wheels and one of the inertia rollers being positioned on either side of the exposure zone of the film. The sprockets 1, 3, 4, Fig. 1, advance a sound film 5 over rollers 55, 57 and a sound-gate aperture plate 7 whereat the film is exposed to the recording or reproducing light beam. The sprocket 3 is supported on a shaft 15, Fig. 2, which is driven from a prime-mover through a gear wheel 17. The sprocket 3 is coupled to the shaft 15 by a spring 19 which is fastened at one end to a pin 21 secured to the shaft 15 and secured at its other end to the sprocket 3 by a pin 23, Fig. 3. A slot 3a in the sprocket 3 allows relative movement of the sprocket on the shaft 15. To prevent free oscillation of the sprocket 3 a washer 25 is compressed between the sprocket and a collar 27 by a spring 29 that engages one face 33 of the sprocket. The upper sprocket 1 is mounted similarly on a sleeve 35 which is damped by a washer 41 compressed between the sleeve 35 and a collar 43 by a spring 45. The collar 43 is rotatably mounted on a stud 37 and is equipped with a pin 49 which engages the threads 51 on the stud 37. The sprocket 4 is a hold-back sprocket and is rigidly secured to a driven shaft 53. Flywheels 56, 58 are mounted co-axially with the rollers 55, 57 respectively to impart to the rollers an inertia effect. Due to the damping means the film is maintained in tension between the sprockets 1, 3 and so held in close engagement with the rollers 55, 57 and the surface of the plate 7. Variations in velocity of the film which might be set up by the damping devices are prevented by the resilient couplings 19, 40. If desired, both sprocket wheels 1, 3 may be driven from the prime-mover. According to a further modification, one of the sprocket wheels, which is then, in general, secured rigidly to its shaft, is driven at a speed slightly greater than the normal film speed at which the other sprocket wheel is rotated.