Magnetic angle encoder and electronic water meter

摘要

A magnetic angle encoder comprising counting wheels, with columnar ring-shaped permanent magnets coaxially mounted to the counting wheels, tunneling magnetoresistive angular displacement sensors, and a digital processing circuit. In the magnetic angle encoder, the tunneling magnetoresistive angular displacement sensors are located in a region within detection planes of the permanent magnets with an axial distance and a specific radial distance from the permanent magnets. Within this specific radius range, the rotating magnetic field angle (Φ) of the component of the magnetic field generated by the permanent magnets in the detection planes varies linearly with the rotation phase angle (α) of the permanent magnets. An electronic water meter is also disclosed, and it comprises a plurality of counting units and a digital processing circuit. The counting units contain counting wheels, permanent magnets, and tunneling magnetoresistive angular displacement sensors. The digital processing circuit is connected to each tunneling magnetoresistive angular displacement sensor, and converts the output of the tunneling magnetoresistive angular displacement sensors into a digital code. The magnetic angle encoder and the electronic water meter have the advantages of small size and high measurement accuracy.

主权项

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.