| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit for detecting the presence of a permanent magnet in the vicinity of an active transplantable medical device, particularly, a pacemaker, a defibrillator, cardioverter and/or a multipoint device. SOLUTION: This circuit is provided with a coil 12 capable of responding to the presence of a magnet 16 so as to indicate a reduction value of an inductance, a resonance LC circuit 10 including the coil, a generator 18 for exciting a pulse of the resonance LC circuit 10, a circuit for analyzing a pulse response of the resonance LC circuit 10 and a discriminating means capable of evaluating a numeric value of the coil inductance from an analytical pulse response and capable of correlatively deciding the presence and the absence of the magnet. An excitation generator can supply a burst of an N continuous pulse to the resonance LC circuit 10, and a discriminating circuit decides the presence of the magnet when the number of M (M<=N) of N pieces of corresponding pulse responses corresponds to the reduction value of the coil inductance.
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