Patent ID: 9103657
Filing Date: 2015-08-11
Classification: G01B,G01D,G01R

Abstract:
1. A magnetic field sensor system for measuring rotational movements of a shaft, the magnetic field sensor system comprising: a biasing magnet configured for generating a biasing magnetic field; a magnetic wheel having a wheel axis and a circumferential surface which comprises a regular structure of teeth and gaps arranged in an alternating manner, wherein the magnetic wheel is attachable to the shaft and the magnetic wheel is magnetizable by the biasing magnetic field; and a magnetoresistive sensor arrangement comprising four magnetoresistive sensor elements being connected with each other in a Wheatstone bridge, respectively two of the magnetoresistive sensor elements being assigned to one half bridge of the Wheatstone bridge, wherein the four magnetoresistive sensor elements are arranged within an x-y plane , wherein an x-axis, a y-axis and a z-axis define an orthogonal Cartesian coordinate system in which the x-axis is oriented parallel with the wheel axis of the magnetic wheel, the y-axis is oriented tangential to the circumferential surface of the magnetic wheel, and the z-axis is the symmetry line through the center of the biasing magnet and the center of the magnetic wheel; wherein the biasing magnet is configured in such a manner that the y-component of the biasing magnetic field is symmetric with respect to the y=0 plane, wherein the biasing magnet is a multi domain magnet and the y-distance between two along the y-axis neighboring magnetoresistive sensor elements is smaller than an outer physical dimension of the biasing magnet along the y-axis.