Patent ID: 8659289

Claim:
A rotating field sensor for detecting an angle that a direction of a rotating magnetic field in a reference position forms with respect to a reference direction, the rotating field sensor comprising: a field generation unit that generates the rotating magnetic field, the rotating magnetic field including a first partial magnetic field in a first position and a second partial magnetic field in a second position, the first partial magnetic field and the second partial magnetic field differing in direction by 180° and rotating in the same direction of rotation; a first detection unit for detecting, in the first position, a first angle that a direction of a first applied field forms with respect to a first direction, the first applied field including the first partial magnetic field as its main component; and a second detection unit for detecting, in the second position, a second angle that a direction of a second applied field forms with respect to a second direction, the second applied field including the second partial magnetic field as its main component, wherein: the first detection unit has: a first detection circuit and a second detection circuit each of which includes at least one magnetic detection element, detects an intensity of a component of the first applied field in one direction and outputs a signal indicating the intensity; and a first arithmetic circuit that calculates a first detected angle value which is a detected value of the first angle, based on the output signals of the first and second detection circuits; the second detection unit has: a third detection circuit and a fourth detection circuit each of which includes at least one magnetic detection element, detects an intensity of a component of the second applied field in one direction and outputs a signal indicating the intensity; and a second arithmetic circuit that calculates a second detected angle value which is a detected value of the second angle, based on the output signals of the third and fourth detection circuits; the output signals of the first to fourth detection circuits have the same period; the output signal of the second detection circuit differs from the output signal of the first detection circuit in phase by an odd number of times ¼ the period; and the output signal of the fourth detection circuit differs from the output signal of the third detection circuit in phase by an odd number of times ¼ the period, the rotating field sensor further comprising a third arithmetic circuit that calculates, based on the first detected angle value and the second detected angle value, a detected value having a correspondence relationship with the angle that the direction of the rotating magnetic field in the reference position forms with respect to the reference direction.