Patent ID: 7791333
Filing Date: 2010-09-07
Classification: G01D

Abstract:
1. An absolute angle detecting apparatus comprising: a rotating body; a rotating magnet that rotates with the rotation of the rotating body; and a magnetic sensor that outputs signals sin θ, cos θ, −sin θ, and −cos θ using a variation in the direction of a magnetic field according to the rotation angle θ of the rotating magnet, wherein first and second arc tangent signals tan−1θ, having phases that deviate from each other by a quarter of the period of each of the signals output from the magnetic sensor, are generated from the output signals of the magnetic sensor, the first arc tangent signal tan−1θ is switched to the second arc tangent signal tan−1θ at an intersecting point between the signal sin θ and the signal cos θ, an intersecting point between the signal −sin θ and the signal cos θ, an intersecting point between the signal sin θ and the signal −cos θ, and an intersecting point between the signal −sin θ and the signal −cos θ, or the second arc tangent signal tan−1θ is switched to the first arc tangent signal tan−1θ at these intersecting points, thereby generating a sawtooth signal, and the rotation angle of the rotating body within one rotation is detected, on the basis of the sawtooth signal.