| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inductance variation detecting circuit that effectively detects variation of inductance with a single coil and realizes a compact and yet high-precision displacement sensor, and to provide a displacement detector and a metal detection device that use the same. <P>SOLUTION: A coil is connected to a rectangular wave AC voltage source, an AC current flowing the coil is converted into a voltage signal, and then passed through a comparator having hysteresis characteristics, so that the inductance variation in the coil is detected as a phase shift at a pulse rise. This configuration can eliminate a necessity of providing two coils like a conventional technique so as to reduce the number of components and realize a high-precision displacement sensor at a low cost. <P>COPYRIGHT: (C)2013,JPO&INPIT |
