Patent ID: 7969147

Claim:
A rotation angle detecting device comprising: a housing; a signal generator including a magnetic rotor that forms a magnetic field and at least three magnetic sensor elements disposed in the magnetic field to respectively generate at least three output signals when the magnetic rotor rotates, said magnetic rotor having a permanent magnet forming the magnetic field, a shaft rotatably supported by the housing; and a rotation angle calculating unit that calculates a rotation angle θ of the rotor based on the output signals, wherein the rotation angle calculating unit is configured to: make a calculation of a first candidate of the rotation angle θ of the rotor from a first pair of the at least three output signals; make a judgment as to whether the first candidate of the rotation angle θ of the rotor is normal or not; make a next calculation of a next candidate of the rotation angle θ of the rotor from another pair of the at least three output signals if the first candidate of the rotation angle θ of the rotor is not normal; make a next judgment as to whether the next candidate of the rotation angle θ of the rotor is normal or not; repeat the next calculation and the next judgment until the next candidate of the rotation angle θ of the rotor is judged normal; and output one of the first and next candidates of the rotation angle θ of the rotor as a formal rotation angle if it is judged normal.