ROTATING SPEED CONTROL DEVICE FOR ELECTRIC MOTOR

摘要

The rotational velocity of a magnetic disc having a magnetic index and driven by a DC motor is controlled. Transducer means responsive to the index derives an electric signal once during each turn of the disc. A clock source derives a plurality of fixed frequency clock waves during each turn of the disc. A counter responsive to the clock source and the electric signal derives a digital signal each time the disc completes a revolution. The digital signal indicates a deviation between the number of clock waves derived by the source during the revolution and a predetermined number, preset into the counter during each turn. A velocity control signal supplied to the motor is controlled by the digital signal.