DESCRIZIONE
A flexible vibration board (12), a piezoelectric element (13) fixed to at least one side of the vibration board (12), and a fixed board (14) and a weight (16) for promoting deformation of the piezoelectric element (13) caused by vibration of the vibration board (12) are provided in the body (10). When the body (10) vibrates by receiving external force, the weight (16) rocks to cause vibration of the vibration board (12), or when the vibration board (12) vibrates, vibration of the vibration board (12) is sustained by the inertia of the weight (16) and the vibration board (12) deforms through vibration thus deforming the piezoelectric element (13) furthermore.
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