| 摘要 |
<p>PURPOSE:To clearly discriminate whether or not there is a magnetic body by detecting synchronously the detected value signal of a detection coil by a phase detection coil as a phase reference. CONSTITUTION:An exciting coil 2 produces a magnetic field with an alternating current from an oscillator 1. Part of this magnetic field penetrates detection coils 3 and 3a, which induce voltages. Further, the phase detection coil 8 is arranged so as to penetrate the magnetic field produced by the coil 2 the same phase at all times. Then the voltage induced cross the coils 3 and 3a are amplified to become detection signals a1 and a2, which are detected synchronously by synchronous detecting circuits 13 and 13a with a synchronizing signal (b) generated by the coil 8.</p> |
