| 摘要 |
PURPOSE:To insure metal other than a magnetic material against being detected erroneously and to detect the raceway of ferrite by magnitizing the moving ferrite by a DC electromagnet and detecting the ferrite by two magnetic sensors separated by a magnetic shield plate. CONSTITUTION:The ferrite 6 comprising the raceway of an unmanned transportation system is moved from left to right. A DC magnetic field generated from a coil excited by an DC power source 8 or a permanent magnet 2 magnetizes the ferrite 6, and the magnetic field is transmitted to two magnetic sensor composed of a hole element 9. The leaked magnetic field will not enter the magnetic sensor shielded by the magnetic shield plate 10. An operation amplifier 5 amplifies differentially the detection signal of the hole element 9, whereby such detection can be made whether or not the hole element 9 deviates from the center of the raceway of the ferrite 6. Since the metal other than the magnetic material such as Al will not be magnetized, the erroneous detection will not occur. |
