Patent ID: 7791336

Claim:
A magnetizable material detection device for detecting a magnetizable material which can be magnetized by a magnet comprising: a first magnet displaceable in the direction of its magnet poles; a Hall device for detecting displacement of the first magnet, having an operating point corresponding to a given magnetic force wherein the on/off state of the Hall device depends on the strength of the magnetic force of the first magnet at the operating point against the given magnetic force; wherein the first magnet and the Hall device are disposed such that when a boundary line of the first magnet poles crosses the operating point, the on/off state of the Hall device changes; a second magnet, being different from the first magnet, for attracting the magnetizable material; and a supporting member, hung by a support plate, for supporting the first magnet and the second magnet whose one end is connected to the first magnet and whose other end is connected to the second magnet; wherein when the magnetizable material is displaced within a predetermined distance from the body of the detection device the second magnet attracts the magnetizable material to cause the supporting member to be inclined so that the boundary line of the first magnet poles crosses the operating point of the Hall device and the on/off state of the Hall device changes, by which the minute displacement of the magnetizable material is detected.