Patent GB-372977-A (GB)
Title: Sound reproducing apparatus
IPC: G03B31/00
Filed: 1931-06-15
Abstract: 372,977. Optical sound-reproducing apparatus. OWENS, F. H., 2647, Broadway, New York, U.S.A. June 15, 1931, No. 17305. [Class 40 (ii).] An apparatus for reproducing sound from a plurality of photographic records extending alternately in opposite directions along a film 31a comprises mechanism driven conjointly with the film-winding mechanism for automatically effecting change in the direction of winding of the film and for laterally displacing the sound-reproducing device relatively to the film. The film 31a is adapted to be wound between two reels 24, 26, Figs. 1 and 4, which are mounted on a vertical supporting plate 2 and are arranged to be driven from a shaft 5 by means of belts 28, 30 and pulley wheels 27, 29, 31. The shaft 5 is also adapted to drive two film sprockets 6, 20, the sprocket 20 being driven through the medium of a belt 16 and pulley wheels 15, 17. The shaft 5 is provided with a large pulley wheel 11 which is driven by belts from a motor 14. The sound record traces are longitudinally arranged side by side on the film, and the reproducing unit consists of a cylindrical housing 32 which is centrally provided with a gate 33. The tube 32, Fig. 1, contains a lamp 35, two lens systems 36, 36b, a slit 34a, and a light-sensitive element 37. To enable the gate 33 to co-operate successively with the various record traces on the film, the housing 32 is adapted to be moved transversely of the film and for this purpose is carried by a slidable rod 38 journalled in the supporting plate 2. A roller 41 mounted on the shaft engages a cam disc 42 which is provided with a stepped surface so that after reproduction from one record trace the housing 32 is moved against springs 40 to cooperate with the next trace on the film. The stepped surface is adapted to be periodically rotated the necessary distance by means of a ratchet and pawl 44, 45 under the control of an electromagnet 46. A braking device for the shaft 5 comprises a flexible strap 58 which is fixed between a pin 59 and the upper end of the armature 61 of a solenoid 62 and passes over a wood, fibre or like braking surface on the shaft 5. The shaft 5 is adapted to drive, by means of bevel and worm gearing, a gear wheel 50 which is mounted on a shaft 49 and carries at its end a pair of adjustable arms 53, 54, Fig. 6, adapted to move over the surface of a dial 51. The dial is calibrated to represent the travel of the film 31a and the arms 53, 54 are adapted to be positioned so that at the end of reproducing one record trace on the film one of these arms moves a pivoted contact arm 57 on the dial into engagement with a stationary contact 56 so as to close an electric circuit including four electromagnets 46, 62, 67, 73. This causes the electromagnet 73 to open a switch 71 so as to stop the film-driving motor, the electromagnet 62 to apply the brake 58 to the shaft 5, the electromagnet 46 to move the reproducer to co-operate with the next record trace, and the electromagnet 67 to move, by means of a ratchet 69 and pawl 68, a pair of insulated contact arms 65, 65a, from one pair X, Z of contacts to a second pair X, Y and thereby reverse the drive of the motor. The arms 65, 65a are connected respectively with ring contacts R, R<1> which are connected with the brush terminals of the armature c of the motor, and the contacts W .. Z are connected as shown to the source of electric current. The contact arm 57 continues to move across the contact 56 owing to the inertia of the pulley wheel 11 on the shaft 5, and when it moves from engagement with this contact the switch 71 is again closed to cause the motor to drive the film in reverse direction until the other arm engages with the contact 57.