| 摘要 |
<p>PURPOSE:To facilitate the balancing of receiving coils by an electric adjustment by arranging a variable capacitor in parallel with one or both of the receiving coils. CONSTITUTION:An object to be inspected in the detection of metal is made to pass between an oscillation coil L1 and receiving coils L2 and L3 connected differentially to each other in the direction of the arrow A so that a magnetic flux generated from the coil L1 and a distribution thereof varies. The variation is detected by the coils L2 and L3. To upgrade the accuracy of detecting metal, a difference signal from the coils L2 and L3 must be zero when no metal passes between the coil L1 and the coils L2 and L3. So, variable capacitors C1 and C2 are arranged across the coils L2 and L3 and the balance of real resistances of the coils L2 and L3 is adjusted coarsely with a variable resistance R. An AC component of the results, especially the balance of an induction reactance portion is adjusted precisely with the variable capacitors C1 and C2 connected in parallel to each end of the receiving coils L2 and L3.</p> |
