| 摘要 |
PURPOSE: To detect the moving speed of any conductive moving object in a non-contact state without applying a mark by detecting the current induced in the moving object by an exciting coil by a magnetic detection coil. CONSTITUTION: When a current (ib) flows to an exiting coil 12b, the magnetic fieldϕpiercing a moving object 10 is increased and a current I is induced in the moving object 10 by the increase of the magnetic fieldϕ. When the moving object 10 moves to the left, an electric power producing current Iv is induced in the moving object 10. Therefore, a current (I-Iv) flows in the vicinity of a magnetic detection coil 12a and a current (I+Iv) flows in the vicinity of a magnetic detection coil 12c. The currents (ia), (ic) corresponding to the magnetic field change by the currents (I-Iv), (I+Iv) are induced in the coils 12a, 12c. When both coils 12a, 12c are reversed in output polarity to be connected in series, a current i=(ia-ic) flows across output terminals A, B. Since the current Iv corresponds to the speed of the moving object 10, the moving speed of the moving object 10 can be detected on the basis of the output current (i).
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