| 摘要 |
PURPOSE:To measure the inclination and vibration of a rock bed in two directions by a single pendulum, by making the pendulum to follow the casing of a main body by feedback control. CONSTITUTION:A pillar shaped pendulum is supported in a main body casing 3 by a ginbal 2, which is constituted by a cross spring, and provided with upper and lower permanent magnets which are driven by electromagnetic coils 17a and 17b in the two directions. A movable electrode 5 at the lower end of the pendulum 1 faces fixed electrodes 6 and 7, which are attached to the inner wall of the main body casing 3, with a minute gap being provided. The magnitude of the gap is changed by the relative movement of the pendulum 1. A high frequency current corresponding to the change flows in a detecting line 10. The current is guided to an output terminal 13 by an output line 14 through a rectifier 11 and an amplifier 12. The output is supplied to an electtomagnetic coil 17a, which is connected to a feedback line 15 through a differential circuit 16. The electromagnetic coil 17a offsets the relative movement of the pendulum 1 with respect to the main body casing 3. |
