Patent ID: 9091565
Filing Date: 2015-07-28
Classification: G01D

Abstract:
1. A magnetic position detection apparatus, comprising: a substrate; a magnet that applies a magnetic field in a z-direction perpendicularly to the substrate; a bridge circuit comprising at least first and second magneto-electric converting elements provided on the substrate, each of which having an electric resistance value that varies with a variance of a magnetic field in association with a movement of a magnetic mobile object; and a detection circuit that detects the movement of the magnetic mobile object according to an output of the bridge circuit, wherein: the detection circuit detects the movement of the magnetic mobile object on the basis of a voltage at a connection node of the first and second magneto-electric converting elements; a surface of the substrate is substantially perpendicular to a magnetization direction of the magnet; the second magneto-electric converting element is, when viewed along the magnetization direction of the magnet, disposed: (a) on a first straight line passing through a center point of a magnetic pole of the magnet and a rotation axis of the magnetic mobile object, the first straight line being parallel to the substrate; or (b) disposed in a vicinity of the first straight line; the magnetic field applied by the magnet on the magneto-electric converting elements is not uniform at each of the magneto-electric converting elements; and the first magneto-electric converting element is disposed in such a manner that, in the absence of the magnetic mobile object, an electric resistance value of the first magneto-electric converting element is substantially equal to an electric resistance value of the second magneto-electric converting element when the magnetic field applied by the magnet is not uniform at each of the magneto-electric converting elements, wherein the magnetic anisotropic axis of both the first magneto-electric converting element and the second magneto-electric converting element are aligned along a same isomagnetic line passing through the first magneto-electric converting element and the second magneto-electric converting element in the absence of the magnetic mobile object.