Position detection device

Abstract

A position detection device for detecting a position of a moving member moving forward and backward in a predetermined moving direction is provided with a detection object attached to the moving member, a substrate provided with an excitation coil for generating a magnetic field in an area including the detection object and a detection coil being interlinked with a magnetic flux of the magnetic field, a power supply unit for supplying an alternating current to the excitation coil, and a calculation unit that calculates the position of the moving member based on an output voltage of the detection coil. The detection coil is shaped as a combination of a pair of curved portions that are symmetrical across a symmetry axis parallel to the moving direction of the moving member. Each of the curved portions is shaped as a sinusoidal fundamental wave component superimposed with a harmonic component of a third or higher order multiplied by each of coefficients corresponding to the order. The coefficients are adjusted in such a manner that a peak value of a voltage induced in the detection coil changes sinusoidally when the detection object moves at a constant speed relative to the substrate while facing a part of the substrate.