| 摘要 |
PURPOSE:To discriminate metallic pieces of different kinds securely by detecting the metallic piece on the basis of the combination of binary-coded signals. CONSTITUTION:The primary coil 2 of a detection part 1 is applied with oscillation voltages of frequencies f1 and f2 and when the metallic piece 4 such as a screw to be detected is present in the magnetic field by the coil 2, electromotive force obtained by the secondary coil 3 according to the frequency f1 or f2 is detected to detect the metallic piece 4. In this case, when a signal of f1 is supplied to the coil 2, electromotive forces obtained by the coil 3 are denoted as EA1-EC1 corresponding to metallic pieces A-C and when a signal of f2 is supplied, obtained electromotive forces are denoted as EA2-EC2; and reference voltages of comparators 9 and 10 are set to the intermediate value of prescribed electromotive forces and binary signals of their comparison results are supplied to a processing circuit 13 to detect the kind of the metallic piece 4 on the basis of the combination of the binary signals. |
