Patent ID: 9709422
Date: 2017-07-18
CPC Classifications: G01B,G01D

Claim:
1. A rotation angle and stroke amount detection device for detecting a rotation angle and a stroke amount of a detection target which generates a magnetic field, the detection target being rotatable about an axis of rotation and linearly displaceable along the axis of rotation, comprising: a sensor unit that includes a plurality of magnetic sensing elements that detect changes in the magnetic field caused by a rotation and a linear displacement of the detection target, the sensor unit outputting a signal based on detection values of the plurality of the magnetic sensing elements; a rotation angle calculation unit that calculates the rotation angle of the detection target based on the signal output by the sensor unit; and a stroke amount calculation unit that calculates a stroke amount of the detection target based on the same signal as that used by the rotation angle calculation unit, wherein two of the plurality of the magnetic sensing elements, which are positioned orthogonal to each other on the axis of rotation, include a sin sensor that outputs a sin signal according to the rotation angle of the detection target and a cos sensor that outputs a cos signal according to the rotation angle of the detection target; the sensor unit includes at least one set of the sin sensor and the cos sensor; the rotation angle calculation unit calculates the rotation angle of the detection target by calculating an arctangent of a ratio between the sin signal and the cos signal; the rotation angle and stroke amount detection device further comprises: a maximum amplitude calculation unit that calculates a maximum amplitude of the sin signal and the cos signal based on a ratio between (i) the sin signal and a sin value, or (ii) the cos signal and a cos value of the rotation angle of the detection target calculated by the rotation angle calculation unit, the maximum amplitude corresponding to the stroke amount of the detection target; and the stroke amount calculation unit calculates the stroke amount of the detection target based on the maximum amplitude calculated by the maximum amplitude calculation unit.