Patent ID: 6496002
Filing Date: 2002-12-17
Classification: G01D

Abstract:
A rotation detector comprising:a rotor including a shaft, wherein a plurality of axial projections are located at predetermined intervals about the rotor; a plurality of magnets located between the axial projections and the shaft; a plurality of magnetism detection elements, wherein each magnetism detection element detects magnetism of a corresponding one of the magnets and includes a plurality magnetoresistors; wherein a movement of the projections changes a flux of the magnets; wherein each magnetoresistor is switched between a first state, in which its electrical resistance is great, and a second state, in which its electrical resistance is small, and the magnetoresistors are divided into two groups, and wherein the groups are substantially symmetrical relative to a group centerline such that, when a direction of the flux changes, the magnetoresistors in one group are in the opposite state from that of the magnetoresistors in the other group; and wherein each magnet and associated magnetoresistors are positioned such that a centerline of changes in the direction of the flux caused by movements of the projections matches the group centerline.