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NEW MOTION PICTURE APPARATUS
During the Conventions of the Society, symposiums on new motion picture apparatus are held, in which various manufacturers of equipment describe and demonstrate their new products and developments. Some of this equipment is described in the following pages; the remainder will be published in subsequent issues of the Journal.
A HIGH-PRECISION SOUND-FILM RECORDING MACHINE*
H. PFANNENSTIEHL**
A recording machine for use in present-day commercial production of soundfilm must not only be capable of propelling film at a constant velocity to produce high-quality records but must also be designed for simple, rapid, and flexible operation.
The Western Electric recording machine described in this paper was designed to fulfill these requirements after an extensive investigation of approved studio practices and of mechanical, electrical, and optical means best suited for soundfilm recording. It is ruggedly constructed of materials selected to give long life with a minimum of maintenance, and all operating mechanisms are enclosed in a compact housing of pleasing appearance.
Fig. 1 is a front view of the recorder with doors closed and film magazine in place. Fig. 2 is a closed rear view, showing the housing on top, which contains a film take-up and drag mechanism, and, at the bottom, four connectors into which may be inserted plugs attached to cabling for all outside circuit connections. The handwheel shown at the left end may be used for turning the film-driving mechanism of the machine.
Film-Driving Mechanism. — The fundamental requirement of a film-recording machine is to propel film past the recording light-beam at a constant speed. In this recorder constancy of film speed is attained by a positive sprocket drive system similar in principle to that employed in the Western Electric recording machine, which has been in use in studios since 1927, but incorporating a number of improvements to assure even more constant and reliable film speed and, consequently, sound records with greater freedom from flutter effects.
The film drive system may be seen in Fig. 3, which is a view of the film compartment of the recorder. The film is propelled through the machine by means of two sprockets driven by a constant-speed motor and a worm reduction-gear
* Posthumous; presented at the Spring, 1937, Meeting at Hollywood, Calif.; received May 24, 1937.
** Bell Telephone Laboratories, New York, N. Y.
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