Control circuit for motor

Claim 1

A circuit arrangement for controlling a motor having a rotor and a winding for driving the rotor in response to a supplied electrical current, comprising: (A) a first reference signal generating circuit for generating a first reference signal indicative of a predetermined rotational speed to which the rotational speed of said rotor is to be adjusted; (B) a second reference signal generating circuit for generating a second reference signal indicative of a predetermined rotational phase to which the rotational phase of said rotor is to be adjusted; (C) a first detection circuit for detecting deviation of the rotational speed of said rotor from said predetermined speed and for producing a first control signal corresponding to said speed deviation; (D) a second detection circuit for detecting deviation of the rotational phase of said rotor from said predetermined phase and for producing a second control signal corresponding to said phase deviation; (E) a third detection circuit for detecting the level of the electrical current flowing through said winding and for producing a third control signal corresponding to said current level; and (F) a control circuit responsive to said first, second and third control signals for controlling the electrical current and voltage to be supplied to said winding; said control circuit being arranged to increase the level of the voltage to be applied to said winding when an increase in the level of the electrical current flowing through the winding is indicated by said third control signal.