| 摘要 |
<p>PURPOSE:To reduce the necessity for readjusting a noise erasing point, by providing a temp. compensating means to an adjustment means for erasing the noise of a product itself and compensating the shift of the noise erasing point accompanied by the change of the circumferential temp. CONSTITUTION:In order to erase the noise of a product, the variable resistor 48 of a phase adjusting circuit 36 is manually adjusted and set so that the shift of the phase of a fundamental wave and that of a detection wave is not generated in the case of a product having no metal mixed therewith. Further, in order to prevent the variation of a product noise erasing point caused by a temp. change, a temp. sensor 40 and a temp. compensating circuit 38 are provided as a temp. compensation means. When a product having a metal mixed therewith passes, the magnetic field formed by a transmission coil is deformed to generate unbalance in the output of a detection coil 28 and, since the phase of the detection wave is shifted from that of the fundamental wave, a timer circuit 44 is operated to exclude the product.</p> |
