| 摘要 |
PROBLEM TO BE SOLVED: To enhance the accuracy of displacement detection, by decreasing magnetization hysteresis generated inside a magnetostrictive wire due to the variations, in a magnetic field resulting from both-way movement of a permanent magnet. SOLUTION: The magnetization hysteresis in the magnetostrictive wire 10 is decreased by a positive and a negative pulse current Pa, Pb whose directions change, by supplying these pulse currents Pa, Pb to the magnetostrictive wire 10 from a current supply part 11, and a torsional elastic waves are generated in the magnetostrictive wire 10 at a corresponding position to the permanent magnet 12. From its propagation time and propagation speed, elastic waves generated by the positive and/or negative pulse current Pa, Pb are detected with a detector 13, and a displacement of the permanent magnet 12 is detected from the propagation time and propagation speed in an operation part 14. COPYRIGHT: (C)2007,JPO&INPIT
|
