PURPOSE: To reduce the power consumption of a pulse motor by driving a pulse motor with small electric power when a load is small and driving it with large electric power when the load is large.
CONSTITUTION: A load detecting circuit 29 short-circuits both ends of a coil at the end of the application of a driving signal to the pulse motor 28 and detects an induced current generated at the coil according to the free attenuation vibration of the rotor. Further, a control circuit 30 is connected between a frequency dividing circuit 26 and a driving circuit 27 and controlled by the circuit 29 to output normally a driving signal. Then when the load circuit 19 detects a heavy load state, a correcting signal which is larger in driving force than a driving signal and has the sample polarity with the driving signal is outputted. Consequently, the load on the rotor can be accurately and stably. Then, the stable operation of the pulse motor can be secured for a long period.
HOSOKAWA MINORU
KAWAMURA KIICHI
OKAZAKI SAKIO
