Patent ID: 7540204

Claim:
A magnetostrictive torque sensor comprising: a rotating shaft that is rotated by an applied torque; a plurality of magnetostrictive regions formed around an entire circumferential periphery of a surface of the rotating shaft, wherein each magnetostrictive region of the plurality of magnetostrictive regions has a magnetic anisotropy different from that of another magnetostrictive region; sensor coils for sensing a change in impedance of the magnetostrictive regions; and torque calculating means for calculating the torque applied to the rotating shaft on the basis of a signal corresponding to the change in impedance outputted from the sensor coils, wherein the magnetostrictive torque sensor has a rate of change in sensitivity greater than or equal to 0.98, and a width W 1 of the magnetostrictive regions in an axial direction of the rotating shaft and a width W 2 of the sensor coils in the axial direction of the rotating shaft are set to fulfill the relationship 1<(W 1 /W 2 )<1.35 so as to keep the rate of change in sensitivity of the magnetostrictive torque sensor at or above 0.98.