Patent ID: 6104186
Filing Date: 2000-08-15
Classification: F02P,G01D,G01P

Abstract:
A rotation detector for detecting an angular position of a gear made of a magnetic material having a plurality of gear teeth and a plurality of gear bases, alternately formed on a periphery of the gear at equal intervals, and side surfaces, each gear tooth having an outer peripheral edge and each gear base being formed along a inner base circle, the rotation detector comprising:a bias magnet for generating a magnetic field in a direction toward the gear;a first magnetoresistance element for generating a signal representing the angular position of the gear teeth, the first magnetoresistance element being placed at a position where the direction of the magnetic field is varied according to the angular position of the gear teeth; anda signal processing circuit for processing the signal to detect the angular position of the gear, even when the gear is not rotating, and wherein:the first magnetoresistance element is elongated so as to define a longitudinal axis thereof and positioned at a peripheral outside vicinity of the outer peripheral edge of the gear at an axial side of the side surface of the gear so that said longitudinal axis of said first magnetoresistance lies generally parallel to a tangent to the outer peripheral edge of the gear; andelectric current is supplied to the first magnetoresistance element, and flows in a direction of said longitudinal axis of said first magnetoresistance element.