PURPOSE: To drive a motor continuously without stopping the motor at a reference point by detecting the change of torque generated in an adjustable jig, etc. by a torque sensor, comparing the torque with a threshold and using a point where the torque reaches the threshold as the reference point.
CONSTITUTION: A torque sensor 4 is stuck to a shaft for a motor 3, and a torque sensor signal SN1 is inputted to a comparator 6 through an amplifier 5, and compared with a comparison level SL as a threshold. the arbitrary quantity of adjustment DA1 is preset previously to a subtraction counter 8 before the charging of a start signal SA in order to adjust the position of a magnetic head 10 while a point where a detecting value reaches the threshold is employed as a reference point. When the counter 8 starts subtraction by a pulse row PU2 and counts the quantity of adjustment DA1 and the detecting value reaches zero, a stop signal SO is inputted to a pulse generator, and an output from a pulse row PU1 is stopped.
BABA MASAICHI
FUJII TERU
