Patent ID: 9638561
Date: 2017-05-02
CPC Classifications: G01D,G01F

Claim:
1. A magnetic angle encoder, comprising: a counting wheel; a permanent magnet mounted coaxially to the counting wheel; a tunneling magnetoresistive angular displacement sensor, wherein the tunneling magnetoresistive angular displacement sensor is located in a detection plane of the permanent magnet in order to detect the magnetic field component produced by the permanent magnet in the detection plane and output a representative signal; and a digital processing circuit that converts the output signal from the tunneling magnetoresistive angular displacement sensor into a digital code representative of a counting wheel rotation angle; wherein, the permanent magnet has a cylindrical ring structure and comprises a first permanent magnet unit and a second permanent magnet unit, said first and second permanent magnet units are symmetrically placed on opposite sides of the diametral cross-section, further characterized in that the first permanent magnet unit and the second permanent magnet unit have a magnetization that is aligned along the axial direction of the cylindrical ring, and in antiparallel directions, or the first permanent magnet unit and second permanent magnet unit have a magnetization that is aligned perpendicular to the diametral cross-section, and aligned parallel to the other; and the tunneling magnetoresistive angular displacement sensor in the detection plane of the permanent magnet is located at a relative distance along the axis and at a specific radius in an inner region of the detection plane, and in the inner region of the detection plane the permanent magnet produces a magnetic field component that is oriented at an angle φ that is linearly proportional to the rotation angle of the permanent magnet.