GB666897A - Improvements in or relating to sound film equipment - Google Patents

Abstract

666,897. Optical and magnetic sound-film apparatus. SHARPLES, N. A. April 11, 1950. [April 9, 1949] No. 9711/49. Class 40 (ii). In a sound reproducing apparatus for film the shafts of the drive sprocket and scanning drum are extended through the casing of the machine and carry a drive sprocket and stabilizing drum, respectively, for a tape carrying a magnetic sound record. In the embodiment described, a sound and picture projector, Fig. 3, has picture projection drive mechanism 18, an objective 17, and optical sound projection components. consisting of a scanning drum 19, light source 20 and drive sprocket 22. When the film carries an optical sound track the film F passes over a roller 21, but when it has an integral magnetic sound track, the film is passed over a transducer 27 and past an erazing head 28. The shafts 23, 24, Fig. 1 carrying the scanning drum 19 and sprocket 22, respectively, are extended through the casing 1 and carry a stabilizing drum 25 and sprocket 26, respectively, for a separate magnetic sound film 30 which is to be run synchronously with a separate picture film, the transducer 27 and erazing head 28 being unplugged from the picture-film side of the apparatus, and plugged into the opposite side, as shown in Fig. 1. When projecting from sub-standard picture film, the linear velocity may be insufficient for good reproduction from magnetic sound film. Provision is therefore made for simultaneously reproducing a separate magnetic sound film at greater linear velocity by passing the said sound film over larger diameter parts of drums 25, 26 on shafts 23, 24, respectively. The take-off spools 4, 5 are mounted on a forwardly extending bracket 2, while the takeon spools are mounted on a similar rear bracket 3 and are driven through spring-loaded friction discs 9, 10, Fig. 5, by a grooved disc 8 coupled to an electric motor 15 by a belt 16.