Patent ID: 6826842
Filing Date: 2004-12-07
Classification: B82Y,G01C,G01R

Abstract:
An azimuth meter, comprising: a plane coil wound into a shape symmetrical with respect to two axes perpendicular to each other; and at least of groups of thin film magneto resistive elements disposed substantially parallel to the plane oft plane coil, in which each of said groups of magneto resistive elements constitutes an MR bridge of an even number of magneto resistive elements electrically connected to each other and detects and outputs two perpendicular components of the earth magnetism, and bearing information is obtained based on the output values, wherein the azimuth meter further comprises: means of passing a current in a predetermined direction through the plane coil to apply thereto a magnetic field that is equal to or higher than a saturation magnetization of said magneto resistive elements, applying a constant biasing magnetic field in the opposite direction, applying a magnetic field equal to or higher than the saturation magnetization of the magneto resistive elements in the direction opposite to said predetermined direction, and then applying a biasing magnetic field in the opposite direction; and means of passing a magnetic field measuring current through the groups of the thin film magneto resistive elements concurrently with the applications of said biasing magnetic fields.