Velocity/phase controller for dc servo motor

Abstract

A controller for properly controlling a rotating speed and a rotational phase of a DC servo motor. A velocity correction signal is obtained by comparing a rotation signal detected from the motor rotating at a predetermined rotating speed, and a phase error signal is detected from the rotation detected signal as well. Both the rotating velocity and phase of the motor are corrected by the controller supplying a signal which is a mix of the velocity error signal and the phase error signal. The invention includes: a velocity control circuit including a trigger pulse generation circuit for producing a trigger pulse, in synchronization with a reference clock signal, from a rotation signal detected in response to the rotation of a motor, a counter for counting the reference clock signal and for outputting a count termination signal when a counted value reaches a preset value, and an output circuit for outputting, in response to the trigger pulse and the count termination signal, either a fast signal representing that the motor rotates faster than a predetermined rotating speed or a slow signal representing that the motor rotates slower than the predetermined speed; the invention further includes a phase control circuit for outputting in resones to a phase difference between the reference signal representing that the motor rotates at the predetermined speed and the rotation detection signal, either an advance signal representing that a phase-angle of the motor is advanced with respect to a predetermined value or a delay signal representing that a phase-angle of the motor is retarded with respect to the predetermined value; and a mixer for mixng an output from the velocity control signal circuit and an output from the phase control circuit, whereby the velocity control of the motor is executed prior to the phase control thereof.