Patent ID: 7696746

Claim:
A motion detecting apparatus comprising: a conductive part to be detected, provided for an object to be detected; a coil generating a magnetic field and disposed so that the part to be detected passes nearby as the object to be detected moves; and detecting means for detecting the motion of the object to be detected by detecting a change in inductance of the coil as the part to be detected passes near the coil, wherein the part to be detected has a fin shape of which width in the motion direction of the object to be detected is narrow at its end confronting the coil, and the part to be detected is inclined with respect to the motion direction of the object to be detected; a passage period in which the part to be detected passes near the coil and a non-passage period are almost the same; the coil is disposed so that its end in a center axis direction faces the object to be detected, and a plurality of parts to be detected are arranged in the motion direction of the object to be detected, at an angle with respect to the motion direction of the object to be detected, in accordance with intervals of the parts to be detected and the diameter of the coil.