Patent ID: 6661225
Filing Date: 2003-12-09
Classification: B82Y,G01D,G01P,G01R

Abstract:
A revolution detecting device comprising:a tunneling magnetoresistance sensor having an element located in a region, said element comprising: a substrate; a pinned layer composed of ferromagnetism material and located to one side of the substrate; a tunneling layer composed of insulating film and located to one side of the pinned layer; and a free layer composed of ferromagnetism film and located to one side of the tunneling layer, said element being configured to detect a change of magnetoresistance of the element according to a magnetic field applied in the region in which the element is located, said change of the magnetoresistance of the element being based on a change of current flowing through the tunneling layer between the pinned layer and the free layer; when determining Cartesian coordinate system such that a center of the free layer is taken as an origin, a magnetization direction of the pinned layer passing through the origin is taken as an X axis, a direction passing through the origin and orthogonal to the X axis and a layer plane of the pinned layer is taken as a Z axis and a direction passing through the origin and orthogonal to an X-Z plane including the X axis and the Z axis is taken as the Y axis, a revolution member disposed in a vicinity of the element in the Y axis from a viewpoint of the element, said revolution member having a surface portion opposite to the element, said surface portion being formed with S poles and N poles which are alternately arranged; and a magnet disposed in a vicinity of the element and generating the magnetic field, a direction of said magnetic field being substantially parallel to the Y axis at a center portion of the element, wherein, when the revolution member revolves, said S poles and N poles are configured to move substantially in parallel to the X axis on the Y axis determined by the element.