| 摘要 |
PURPOSE:To follow either frequency of resonance or anti-resonance of an oscillator and perform the driving by constituting a driving apparatus wherein a driving signal is FM-modulated and the frequency of the driving center is adjusted based on the change in amplitude of electric current synchronizing to the modulated signal. CONSTITUTION:Amplitude of the electric current energized in an oscillator 1 consisting of a piezoelectric or electrostrictive element is detected by means of an electric current detector 4 and an amplitude detector 5. Whether change in the amplitude of electric current generated by the change in driving frequency caused by FM modulation is the same plase or the reverse phase to the signal of FM modulation is judged by the polarity of output signal in a synchromized detector 6. In addition, the central frequency of an electric voltage controlling oscillator 2 is increased and in accordance with the output signal of the synchronized detector 6. The driving frequency is made thereby to coincide with either a resonance frequency or an anti-resonance frequency of the oscillator 1. Namely, a driving signal is FM-modulated and it is possible to follow any frequency of the oscillator 1 by constituting a driving apparatus adjusting the driving central frequency based on the change in the amplitude of electric current synchromized thereto. |
