Patent GB-321148-A (GB)
Title: Improvements in and relating to sound reproducing apparatus and particularly talking motion picture apparatus
IPC: G11B25/10
Filed: 1928-07-20
Abstract: 321,148. Beatty, W. E., (Bell Telephone Laboratories, Inc.). July 20, 1928. Electric circuit applications ; driving ; starting and stopping; combined working of sound-reproducing apparatus with kinematographs.-Soundreproducing apparatus, particularly for use in talking motion-picture apparatus, is adapted to enable different types of sound records to be employed as desired, and amplifiers are provided, by means of one or more of which, as necessary, the resultant outputs from all the reproducers are rendered equal. The machine shown comprises a kinematograph projector with which picture films bearing photographic sound-records may be used, the film being fed through photoelectric reproducing apparatus after passing through the projector. The motor that drives the film-feed mechanism is also adapted to drive a gramophone having an electric pick-up, which mav be used instead of the sound-film, when desired. A common loud-speaker is used for both systems of reproduction, and includes the usual amplifier to which the gramophone pick-up may be directly connected. When, however, the sound-film system is used, the output from the photo-electric cell is fed to an auxiliary amplifier, so that currents of the same order of magnitude are applied to the main amplifier from either reproducer. The whole machine is mounted on a bed-plate 1, which directly supports the motor 4. A bracket 10 bolted to the plate 1 supports a gramophone turntable 9, which is surrounded by a guard-rail 12. The pick-up arm 15 is pivoted on a support extending up from the bracket 10. The turntable is driven by a shaft extending from the motor, power being transmitted through flexible joints 7, 8 and a mechanical filter such as that described in Specification 271,810. From the other end of the motor, power is transmitted through a fly-wheel 17 to a gear-box 18, the main shaft driven by the motor carrying a hand-wheel 19 to enable the shaft to be slowly turned by hand when necessary. Vertical spindles 20, 21, driven from the gear-box operate mechanism which feeds the film through a picture projector and through the optical sound-reproducing apparatus. A further spindle drives the shaft on which the take-up spool is mounted. This spool is housed in a magazine 27 which is bolted to the bed-plate 1, 4 on which is mounted a, bracket 31 provided with trunnions supporting a tiltable upper base. On this base, which may be clamped in any position to which it is adjusted, is carried the projector head 67, which may be of any standard construction, and is fixed by adapter plates. The sound-reproducing apparatus, which is also fixed to the upper base, comprises a casing having separate compartments 50, 51, 52 for a constant-intensity lamp, an optical system, and a photo-electric cell respectively. In the compartment 51 is also housed a driving sprocket engaging the film, the sprocket being mounted on a shaft passing through the bushing forming the axis about which the upper base may be rotated. This shaft carries a fly-wheel 31<1>, and is driven from the spindle 21, Fig. 1. An amplifier to which the output from the photoelectric cell is fed is mounted in a box 53, and is provided with a rheostat 55 and a meter 56. A cable 57 carries connections from the main amplifier (not shown), either to the auxiliary amplifier in the casing 53, or to the gramophone pick-up 16, according to the setting of a switch 54. A pedal 58 controls the starting and stopping of the machine. When lifted, it removes a brake shoe from the fly-wheel 17, and also closes the circuit of the motor 4. Depression of the pedal stops the apparatus. The projector head is driven from the spindle 20 by a telescopic shaft 66 provided with universal joints 64, 65 and with means for maintaining the end sections of the shaft parallel. Specifications 320,864. [Class 80 (ii), Gearing, Variable-speed &c.], 322,233, 322,234, and 322,235 are referred to.