| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a foreign-matter detecting apparatus by which a foreign matter having a prescribed size can be detected surely. SOLUTION: This apparatus is provided with a reaction-signal generation circuit 2 which detects a change in the distribution of a magnetic flux generated at the time when an object P is passed through a magnetic field and which outputs a reaction signal. The apparatus is provided with a judgment circuit 10 in which a value in the prescribed phase point p1 of the reaction signal is compared with a threshold value SH and which judges the existence of a foreign body. The apparatus is provided with a sensitivity adjusting means 12A which adjusts the detecting sensitivity of the reaction-signal generation circuit 2 in such a way that the value of a first test reaction signal A in the prescribed phase point p1 at the time when the object P to which a foreign body, to be detected, having a minimum size is passed in the magnetic field becomes a prescribed level with reference to the threshold value SH.</p> |
