Patent ID: 6600311
Filing Date: 2003-07-29
Classification: G01D

Abstract:
A magnetic sensor comprising:a rotating shaft that interlockingly rotates with an object to be detected; an arc-shaped metal member, interlocked with the rotating shaft to rotate with the rotating shaft along a circular trajectory around a center of the rotating shaft, the arc-shaped metal member comprising a plurality of arm portions that extend along substantially half of a circumference of a circle defined by the circular trajectory; a pair of opposing arc-shaped sensor coils, symmetrically positioned around the rotating shaft on the circular trajectory, each of the arc-shaped sensor coils defining a center air core, which is partially occupied by at least a portion of a corresponding one of the plurality of arm portions; and a sensor circuit that excites the sensor coils and detects a magnetic change in a high frequency modulated magnetic field, generated by each sensor coil in response to a movement of the rotating shaft, which causes each of the plurality of arm portions to move within the respective sensor coil center air cores, the sensor circuit generating a signal indicating a rotation angle of the rotating shaft based on the magnetic change detected from each sensor coil; wherein a relationship between occupation amounts of the plurality of arm portions within the corresponding center air cores remains complementary throughout the movement of the rotating shaft.