| 摘要 |
PURPOSE:To make the length of a coil device shorter than that of a displacement to be detected by connecting a detecting circuit to the variable inductance coil device wherein a coil having a core moving therein and another coil housing another core and covered by a movable metallic outer cylinder are combined with each other. CONSTITUTION:First and second coils are arranged in parallel on a base plate and each coil is fixed to the base plate by a coil fixture at one end. The other end of the first coil has a shielding pipe fixed to the base plate by a fixture. The other end of the second coil is not fixed and the fixture is provided with a through-hole to allow the metallic outer cylinder of the second coil to pass therethrough. The connecting rod of the core of the first coil and the moving rod of the metallic outer cylinder of the second coil are connected to each other by a connector to integrally move. Changes in inductance due to putting in and out the core and due to the movement of the metallic outer cylinder are in reverse direction to each other. When the contrastive changes in the inductance are changed to changes in voltage and differentially taken out, a DC voltage equivalent to the quantity of a displacement is obtained. In this case, the length is halved as compared with two coils connected to each other in series for the same length of the displacement to be detected.
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