| 摘要 |
PURPOSE: To stabilize vibration waves by canceling out the non-uniformity in the positional phase difference of each vibration being generated by the partial non-uniformity of the stiffness of a vibration body by partially changing the stiffness of the vibration body. CONSTITUTION: An elastic body 1 of the vibration body is provided with a plurality of grooves 4 for enlarging displacement in the peripheral direction being generated by bending vibration. Also, the minimum unit of the arrangement of a pattern electrode 3-1 of a piezoelectric element 2 is 1/4 wavelength, and the groove 4 is equally divided into 28 portions in a peripheral direction to allow all areas 3-3 between electrodes 3-3 to coincide with the position of the groove 4. Then, the groove 4 where an angle coincides with the areas 3-3 between the pattern electrodes of the piezoelectric element 2 is made shallower than other grooves, and the decrease in the bending stiffness of a vibrator is corrected by increasing the sectional area of the vibrator and hence increasing the sectional secondary moment. As a result, the propagation speed of the vibration of a standing wave with a different phase being formed at the vibration body does not change at a part corresponding to the areas between the electrodes of the piezoelectric element, thus stabilizing the waveform of traveling waves with traveling properties.
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