Patent ID: 6924639
Filing Date: 2005-08-02
Classification: F02D,G01D

Abstract:
1. A position detecting device comprising: a rotor having gear-teeth around an outer periphery thereof; a bias magnet for projecting a bias magnetic field toward the gear-teeth; a magnetic sensor having at least first, second, third, and fourth magnetoresistive element bridges arranged between the rotor and the bias magnet, wherein the magnetoresistive element bridges produce outputs that vary according to a direction of the bias magnetic field; and a differential output calculation means that performs a multistage differential calculation from the outputs of the magnetoresistive element bridges and obtains a single differential output, wherein the first and the second bridges are positioned symmetric to a magnetic axis of the bias magnet, the third bridge is positioned at a midpoint between the first bridge and the magnetic axis, and the fourth bridge is positioned at a midpoint between the second bridge and the magnetic axis.