| 摘要 |
PURPOSE: To provide a variable capacitor which is even a single element but high in withstand voltage, high in frequency stability, small in size, and large in variable rate of electrostatic capacitance. CONSTITUTION: A counter electrode 15 serving as a movable electrode is supported by long and thin beams 17B and 17B long in cross section and set movable. A board surface electrode 12 is provided confronting the counter electrode 15, and a stationary electrode 6 is provided confronting the movable electrode. An external bias voltage is applied between the movable electrode and the stationary electrode through the intermediary of a lead electrode 10 and a lead electrode 11A or 11B, a coulomb force is induced between the movable electrode and the stationary electrode to enable the stationary electrode to attract the movable electrode, and on the other hand, the elastic force (restoring force) of the beams acts on the counter electrode 15 to return it to an original position, so that the counter electrode is displaced up to a point where the coulomb force and the elastic force of the beams are balanced. The overlap of the counter electrode with the board surface electrode is changed in area with the displacement of the counter electrode, so that an electrostatic capacity between the counter electrode and the board surface electrode is changed.
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