| 摘要 |
A piezoelectric oscillator that generates a travelling wave using two B (1, n) mode (n is a natural number) standing waves that are out of phase with each other by 90°. On a lower surface of an oscillating body, (4/3)n piezoelectric elements are provided in order to generate an n-wave travelling wave by combining the two B (1, n) mode standing waves that are out of phase with each other by 90°. When a wavelength of the travelling wave is given by λ, each of the piezoelectric elements has a dimension in a circumferential direction occupying a central angle corresponding to (1/2)λ&thetas;, and a plurality of piezoelectric elements are spaced apart from each other at intervals each occupies a central angle corresponding to (1/4)λ&thetas;.
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