| 摘要 |
PROBLEM TO BE SOLVED: To detect the rotation amount of a movable electrode with a small arithmetic amount in a rotary actuator.SOLUTION: A first DC power supply 400 is connected to a movable electrode 120, and an AC power supply 410 is connected to a fixed electrode 140. A capacity detection part 200 detects a capacity between the movable electrode 120 and a detection electrode 150. The capacity detection part 200 includes an operational amplifier 210 and a second DC power supply 240. The operational amplifier 210 is virtually short-circuited. Also, an inverted input terminal (-) of the operational amplifier 210 is connected to the detection electrode 150. The second DC power supply 240 is connected to a non-inverted input terminal (+) of the operational amplifier 210. A control part 300 controls a first DC power supply 400 on the basis of the detection result of the capacity detection part 200. The control part 300 controls the voltage of the detection electrode 150 such that a voltage between the detection electrode 150 and the movable electrode 120 becomes a reference value.SELECTED DRAWING: Figure 1 |
