GB349070A - Improvements in talking picture synchronising apparatus - Google Patents

Abstract

349,070. Maintaining proportional speeds of motors. MITCHELL, F. A., 102A, Philbeach Gardens, Earl's Court, London. Feb. 10, 1930, No. 4457. [Class 38 (iii).] Comprises synchronizing means for talking picture apparatus wherein the motor driving the sound reproducing or recording apparatus controls the speed of the kinematograph driving motor. A variation in the relative speeds of the motors functions automatically, by means not in circuit with the kinematograph driving motor, to adjust a continuously variable resistance in permanent circuit with the driving motor of the kinematograph. On a rotating part of a sound reproducing apparatus X is attached a commutator A with contact segments A<1> and contact brushes B<1>, D. A commutator C having a contact C<1> to cooperate with brushes B<2>, B<3>, S, F is attached to the shaft of the projector driving motor M. The brush B<1> is electrically connected to the brushes B2, B<3>, the brush D being connected to an electric supply E and thence to the centre terminal G of a reversible control motor H, the other terminals F2, S<2> of which are connected to the brushes F, S respectively. The motor H operates a worm W to rotate a resistance R to vary the resistance in the supply circuit to the motor M. When the machines are running in synchronism no current will flow to the motor H and the resistance R will remain at one setting. Should the projector run at a higher speed the brushes B<3>, S will contact with the segment C<1> at the same time as the brushes B<1>, D, make contact with a segment A<1> and current will flow to the terminal S<2> on the motor H which will rotate the worm W to increase the resistance in the supply circuit. If the projector runs at a lower speed current will flow to the terminal F<2> to rotate the worm W in the reverse direction to reduce the resistance. The projector commutator brushes may be mounted on a frame so that if the projector and sound reproducer shafts are initially rotating in synchronism but out of phase the brushes may be rocked round the commutator C until the sound and pictures are in step. Alternatively, the switches S<3>, F<3> may be closed to advance or reverse the motor H. Specification 332,004, [Class 40 (ii), Phonographs &c.], is referred to.