| 摘要 |
A resonant actuator includes a driving unit having a displacement element that vibrates at a resonance frequency or in a frequency range in the vicinity of a resonance frequency and having a driven member that is driven by the displacement element, in which the displacement element has a piezoelectric ceramic body made of a bismuth layered compound. The displacement direction of the displacement element is preferably substantially the same as the direction of polarization of the piezoelectric ceramic body. The bismuth layered compound is preferably oriented such that the direction of the c crystallographic axis is substantially perpendicular to the direction of polarization of the piezoelectric ceramic body. More preferably, the degree of c-axis orientation is determined to be at least about 75% by the Lotgering method. Thereby, it is possible to provide a resonant actuator having a large saturated vibration velocity, minimizing reductions in the resonance frequency fr and the mechanical quality factor Qm without the destabilization of the vibration velocity even at a high vibration velocity, and having a large amount of displacement even at a high electric field.
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