Patent ID: 7584673

Claim:
A magnetostrictive torque sensor comprising: a magnetostrictive portion provided on a shaft; first and second torque detection coils disposed opposite the shaft, wherein at least one first and second torque detection coil detects a torque applied to the shaft, a demagnetization circuit (C) demagnetizes the shaft via said at least one first and second torque detection coil, and the demagnetization circuit (C) provides an excitation function to said at least one first and second torque detection coil; and torque calculating means for calculating the detected torque, wherein the detected torque is calculated by an equation: VT 3 =k ( VT 1 −VT 2)+ Vb wherein VT 1 is a first voltage signal detected by the first torque detection coil facing a first magnetostrictive portion, and when the steering torque increases, the first voltage signal increases, and wherein VT 2 is a second voltage signal detected by the second torque detection coil facing a second magnetostrictive portion, and when the steering torque increases, the first voltage signal decreases, and Vb is a bias voltage.