Patent ID: 6966232

Claim:
A torque sensor, comprising: a magnetic metal film with magnetic anisotropy attached to a torque transmission shaft; an exciting coil and a detector coil each installed near the magnetic metal film; an excitation power supply source that generates an excitation power having a voltage (Vcc); an ac excitation signal generator ( 74 , 76 , 78 ) that is connected to the excitation power supply source to input the excitation power having the voltage (Vcc) and generates an ac excitation signal (Vsin) to be supplied to the exciting coil; a reference voltage generator that is connected to the excitation power supply source to input the excitation power having the voltage (Vcc) and generates a reference voltage (Vref), indicating a midpoint of the ac excitation signal (Vsin), that is set to a voltage corresponding to a 50% duty ratio of the excitation power having the voltage (Vcc); and a torque detector that is connected to the detector coil and detects a torque applied to the torque transmission shaft based on an output of the detector coil when the torque is applied.