| 摘要 |
The effective thickness of a piezoelectric unit comprising a plurality of contiguous layers is varied by selectively short circuiting one or more layers with switch means. This varies the electro-acoustic properties at an operating frequency that is exhibited between the respective acoustic ports of the unit and an electrical circuit coupled across the electric port of the unit. Specific embodiments of such a unit, switch means and electrical circuit are useful in a control device for acoustic-wave propagating systems.
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