Magnetic encoder

Abstract

In a magnetic encoder (1), a permanent magnet (20) as a magnetic scale is provided with three rows of tracks (21) wherein N poles and S poles are alternately arranged along a shift direction. In the permanent magnet (20), at end portions (211) in the width direction of the tracks (21A, 21B, 21C), a rotating magnetic field wherein a planar direction changes is formed, and a sensor plane (16) of a magnetic sensor (15) faces a boundary portion (212) between the tracks (21A, 21B, 21C). Thus, detection accuracy of the magnetic encoder of the rotating magnetic field detection type is improved.

Description

technical field [0001] The present invention relates to a magnetic encoder comprising: a magnetic sensor with a magnetoresistive element on a sensor surface, and a permanent magnet that moves relative to the magnetic sensor. Background technique [0002] The magnetic encoder includes: a magnetic sensor with a magneto-resistive element on the sensor surface, and a permanent magnet that moves relative to the magnetic sensor. On the permanent magnet, a magnetic track with N poles and S poles alternately arranged along the moving direction (for example, Refer to Patent Documents 1, 2, and 3). [0003] There are generally two types of such magnetic encoders, one is the type that detects the position according to the strength of the magnetic field in a certain direction, and the other is the type that detects the direction of the rotating magnetic field by the magnetic field strength above the saturation sensitivity area. The latter is a representative type of magnetic encoder, w...

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Problems solved by technology

[0013] However, as shown in FIG. 11( b ), when the linear encoder 201 is constructed so that the sensor surface 216 faces in a direction perpendicular to the permanent magnet 220, there is a region where the magnet

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