Patent ID: 9200884
Filing Date: 2015-12-01
Classification: G01B

Abstract:
1. A magnetic sensor system comprising a scale and a magnetic sensor that are arranged in a relative positional relationship variable in a first direction, the magnetic sensor system being configured to detect a physical quantity associated with the relative positional relationship between the scale and the magnetic sensor, wherein the magnetic sensor includes a first detection circuit disposed at a first position, a second detection circuit disposed at a second position, and a third detection circuit disposed at a third position, the first detection circuit outputs a first detection signal that varies depending on a first magnetic field applied to the first detection circuit, the second detection circuit outputs a second detection signal that varies depending on a second magnetic field applied to the second detection circuit, the third detection circuit outputs a third detection signal that varies depending on a third magnetic field applied to the third detection circuit, each of the first to third detection circuits includes a magnetoresistive element, the magnetoresistive element includes: a magnetization pinned layer having a magnetization in a pinned direction; a free layer having a magnetization that varies depending on an applied magnetic field; and a nonmagnetic layer interposed between the magnetization pinned layer and the free layer, each of the first to third magnetic fields changes its direction periodically in response to a change in the relative positional relationship between the scale and the magnetic sensor, the relative positional relationship between the scale and the magnetic sensor is changeable by two pitches or more, where one pitch is an amount of a change in the relative positional relationship between the scale and the magnetic sensor that changes the direction of each of the first to third magnetic fields by one period, two of the first to third positions that are the most distant from each other in the first direction are different from each other by one pitch or less in the first direction, the first to third detection signals change periodically in response to a change in the relative positional relationship between the scale and the magnetic sensor, and have mutually different phases, the magnetic sensor system further comprises a computing unit that generates a first post-computation signal by computation using at least the first detection signal and the third detection signal and generates a second post-computation signal by computation using at least the second detection signal and the third detection signal, and the first post-computation signal and the second post-computation signal change periodically in response to a change in the relative positional relationship between the scale and the magnetic sensor, and have mutually different phases.