US Patent 7262594 Rotation angle detector

A rotation angle detector includes a rotator, a detecting rotator, a magnet, an anisotropic magnetoresistive element, an amplifier, and a controller. The controller connects an output terminal of the anisotropic magnetoresistive element to the ground so as to detect a short circuit between adjacent output terminals based on the difference in output voltage from the amplifier. When there is no short circuit, the controller releases the connection from the output terminal to the ground, and detects the rotation angle of the rotator from the output signal that is differentially amplified by the amplifier based on the output signal of the anisotropic magnetoresistive element.