| 摘要 |
A second piezoelectric vibrator (30) is located in a hollow portion (21) of the first piezoelectric vibrator (20) when seen in a plan view. A support (40) is a frame-shaped member, and the inside surface thereof supports the edge of a vibration member (10). The fundamental resonance frequency of the first piezoelectric vibrator (20) is lower than the fundamental resonance frequency of the second piezoelectric vibrator (30). In addition, the second piezoelectric vibrator (30) overlaps a loop of vibration generated in the vibration member (10) when the first piezoelectric vibrator (20) is driven at the fundamental resonance frequency. Preferably, the center of the second piezoelectric vibrator (30) overlaps the center of a loop of vibration generated in the vibration member (10) by the first piezoelectric vibrator (20).
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