Two-speed by-directional, closed loop stepper motor control circuit

Claim 1

A stepping motor control system for controlling a stepping motor in both directions and at different speeds, comprising, in combination, a stepping motor of the type having a plurality of windings, the direction and speed of rotation of the motor being dependent upon the sequence and frequency of pulses supplied to the motor, a single feedback encoder driven by said motor for supplying serial feedback pulses on a single feedback signal line in accordance with the speed of rotation of said motor, bidirectional counter means connected to said motor for providing motor control output pulses in predetermined sequence for sequentially energizing the winDings of said stepping motor, direction control means connected to said counter means for selectively reversing the sequence of said counter means to thereby selectively reverse the direction of rotation of said motor, starting means for starting said motor including run trigger means turned on by a run command signal for supplying a starting sequence signal to said bidirectional counter means, run control means governed by said starting means for supplying said serial feedback pulses from said encoder and said single feedback signal line to said bidirectional counter to thereby enable continuing operation of said motor, high-speed control means governed by a high-speed control signal and effective when rendered operative to supply an additional pulse to said bidirectional counter, for advancing the field of the stepping motor to an advanced position, effective to cause the motor to accelerate to a high-speed operation, and decelerating control means connected to said counter and governed by said high speed control means and effective when the high speed control signal is terminated for retarding the field of said stepping motor by causing said counter to skip a control pulse.