| 摘要 |
PURPOSE: To stabilize phase differences even at such a high frequency that makes the phase difference unstable by connecting an impedance element in series with a vibration detecting section and connecting the signal impressed upon the vibration detecting section to the impedance element. CONSTITUTION: A capacitor 12 which is an impedance element is arranged so that its A-phase side (A-phase driving side) can be connected in series with its S-phase side (vibration detecting side). When the capacitor 12 is connected in such a way, an A-phase driving piezoelectric element and vibration detecting piezoelectric element are made to be the same phase in position and the phase difference θA-S is made to become +90 deg.. The phase difference can be expressed as the constitution of the capacitance component Cs on the vibration detecting piezoelectric element side and the capacitance component Cin obtained by the capacitor 12 connected in series with the S-phase. When the Cin/Cs is changed, the magnitude of the signal impressed upon the S-phase can be adjusted. When the magnitude of the signal is adjusted so that the magnitude can fall within a range front the 1/20 to the 1/3 of the output voltage of the vibration detecting section at the resonance frequency, the phase difference θA-S can be stabilized at 0 deg. (the same phase as A-phase). |
