GB978562A - Improvements in or relating to electrical drives for moving picture film cameras - Google Patents

Abstract

978,562. Control of A.C. motors; converting. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Feb. 2, 1961 [Feb. 5, 1960], No. 3987/61. Headings H2F and H2J. [Also in Division G2] A multiphase synchronous electric motor 2 driving a cine camera is supplied, e.g. from a battery, via a unit 23 controlled by an oscillator 21, 22 whose frequency thus determines the speed of the motor. A D.C. braking winding 26 is switched by a further transistor 24. The unit 23 may comprise a pair of transistors in each phase which connect three-phase motor windings to alternate poles of the supply when triggered by oscillator 21, 22, which then has a three-phase sine wave output (Fig. 4, not shown); alternatively, the unit 23 is a decade ring counter supplying a five-phase motor and the triggering oscillator is single-phased (Fig. 7, not shown). Camera shutter position signals are given by cam-operated contacts or a magnetic or photo-electric device with a three-phase motor, while in the five-phase arrangement signals are generated in the ring counter. The unit 23 is switched by a transistor 25 controlled by an arrangement of " and " and " or " gates 20 to control the camera in any of the following ways by push-button selection:-(1) camera runs continuously while the operating button is held depressed, (2) the button is pressed to start continuous running and pressed again to stop it, (3) a single frame is exposed each time the button is depressed, (4) the shutter remains open while the button is held depressed, (5) single frames automatically exposed in succession with an adjustable time interval between each. Provision is made for synchronizing a flash light or further cameras, and for remote control; also the motor may be reversed.