GB359519A - Improvements in control gear for projectors of talking films - Google Patents

Abstract

359,519. Kinematograph apparatus. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and PETERS, W. H., of General Electric Co., Wembley, Middlesex. July 11, 1930, No. 21010. [Class 97 (i).] Change-over from one projector to another, together with change-over from one sound-reproducing apparatus to another, and volume control of the output, is effected as desired by a device comprising a switch arm which has both rotary and lateral motion and works in a casing having an H-gate. Fig. 1 (Prov.) shows the arrangement of the arm a in the gate, the arm being mounted on a shaft to which rotary movement is imparted as the arm is moved up or down either of the vertical slots, and axial movement is given by passing the arm through the horizontal slot. The arm a has a pushbutton b which controls the motors of the two projectors through a commutator C, Fig. 2 (Comp.), having contact segments 9 .. 13, connected in circuit as shown with the mains 15, 16 and with starter switches 17, 18 for the two projectors respectively. A contact 14 associated with the arm a bridges segments 9 and 12 or 9 and 13, according to the position of the arm, while segments 10 or 11 are connected to the segment 9 only when the button b is depressed. The arrangement is such that, when the arm is in the upper half of either of the vertical slots of the gate, starter switch 17 is closed, and the motor and projector associated with it are running : soundreproduction is effected from a disc record, when the arm is in the right-hand slot, and from a film record, when the arm is in the left-hand slot. To change over from the first projector to the other, the button b is depressed, closing the circuit of the starter switch 18 of the second motor through the segments 9, 11. With the button still depressed, the arm a is swung down to the lower half of either vertical slot. The switch 18 for the motor of the second projector then remains closed through the segments 9, 13, and the pressbutton is released. The movements of the arm also control a commutator 5, Fig. 1 (Comp.), which according to the position of the arm, either connects the gramophone pickup D<1> or the sound film reproducer F<1>. associated with one projector, to a volume-control potentiometer 8, or connects the pick-up D<2> or sound-film reproducer F<2> associated with the other projector, to the potentiometer 8. The latter, which is connected to an amplifier 7 operating loud-speakers S, comprises a slider contact operated by movement of the arm a in the vertical slots of the gate, the arrangement being such that when the arm is at either extreme position the maximum volume is reached, and when the arm is at the central position the volume is zero. The volume of sound is controlled by proper adjustment of the arm in the selected branch of the H-slot.