| 摘要 |
PURPOSE:To suppress vibration of unnecessary wave by combining vibration signals, detected at plural points on a vibrating body, and taking out a signal representative of unnecessary vibration in which vibration component for driving the vibrating body is attenuated. CONSTITUTION:A second phase S piezoelectric element 1-4 (hereinafter referred to phase S2) is arranged at a position rotary symmetrical to a phase S piezoelectric element 1-1 (hereinafter referred to phase S1), i.e. a position separated by a distance of (lambda8/2)X8; where lambda8 is the wavelength in case of 8 waves. Difference between the outputs from the phase S1 and S2 piezoelectric elements is then produced by means of a subtractor 7. The differential signal is then amplified through an amplifier 8 and provided to a driving phase 1-5 for suppressing unnecessary vibration arranged on the vibrating body. |
