| 摘要 |
The device comprises a vibrator (15) with a piezoelectric transducer (17) for generating an elastic wave which advances along a closed trajectory (61). The transducer (17) has first, second and third transducer sections (17a, 17b, 17c, 17d, 17e, 17f) distributed along the trajectory (61), to which first, second and third cyclically varying excitation voltages (U1, U2, U3), respectively, are supplied during operation. The distance between the sequentially arranged first, second and third transducer sections (17a, 17b, 17c, 17d, 17e, 17f) is less than one quarter, in particular one sixth, of the wavelength. The first and third excitation voltages (U1, U3) are out of step with the second excitation voltage (U2) by a phase angle less than +/-90 DEG , in particular +/-60 DEG . During operation, the transducer (17) converts the electrical energy supplied to it by means of high shearing strains which generate the elastic wave. |
