Spindle orientation control apparatus

A spindle orientation control apparatus which comprises:

• a motor for driving a spindle;
• speed control means for rotating the spindle at a speed in accordance with a command speed;
• position control means for stopping the spindle at a commanded spindle stopping position;
• stopping position command means for digitally instructing the commanded spindle stopping position;
• a position sensor for generating a one-revolution pulse each time the spindle makes one complete revolution and a position pulse each time the spindle rotates by a predetermined angle;
• error monitoring means for monitoring an error between said commanded spindle stopping position and the actual rotational position of the spindle upon receiving each of the pulses generated by said position sensor, said error monitoring means generating a signal when the error attains a predetermined value;
• and
• means for generating a signal indicative of an orientation speed;
• the spindle being speed-controlled so as to rotate at the orientation speed until said error monitoring means generates said signal, and positioned-controlled after the generation of said signal so as to reduce the error to zero, the speed and position control operations being performed when the apparatus is in a spindle orientation control mode.