Analysis of Sound-Film Drives

In order to avoid audible flutter, the velocity of sound-films past the scanning light-beam must not vary more than about 0.1 per cent. Such precision can not be obtained solely by constant speed motors and high-quality gears. Mechanical filters must suppress the “drive side” disturbances originating in motor, gear-train, and sprocket-teeth, and the “load side” disturbances due to variations in the film and in the friction load. — Early designs filtered only the drive-shaft rotation and steadied the film by recording on a large sprocket drum. Filtered sprockets in combination with fixed reproducer gates were not adaptable to modern requirements and were superseded by film-driven damped impedance drums(rotary stabilizers). — The recommended design avoids the troublesome inner flywheel bearings by a liquid stabilizer and overcomes the uncertain filtering properties of film compliance by means of elastic driving sprockets.

Print ISSN

0097-5834

Published

1941-11

Content type

Original Research

DOI

10.5594/J01245