| 摘要 |
PURPOSE:To stabilize operation with a relatively simple structure, by using a permanent magnet as a detecting element for the position that displaces in accordance with the travelling of a travelling member. CONSTITUTION:An ultrasonic transmissive member 2 is arranged along the displacement process of a permanent magnet 1 that displaces to a position in correspondence with travelling of a travelling member, and around the member 2 a coil 3 is wound. Further, the ultrasonic pulse from a cable transmitter 5 propagates through an internal part of the member 2, and when it reaches a part corresponding to the position of the magnet 1, a voltage is generated in the coil 3 owing to the cooperation between the magnet 1 and the coil 3, and further, after amplification 4, the voltage is supplied to an operational circuit 7. In the circuit 7, with the input signal from the transmitter 5 as reference, the time needed for the ultrasonic wave to reache a wave receiver 6 and the time needed for it to reach the magnet 1 are calculated, and further a signal corresponding to the position of the magnet 1 is outputted. |
