| 摘要 |
PURPOSE:To efficiently drive by bringing current values of the current flowing to two electrode groups into coincidence in a real time, and exciting only the traveling wave of a bending vibration of a piezoelectric drive unit. CONSTITUTION:A resistor RA is connected in series with electrode group A, and a drive voltage is applied to a power amplifier 9. A resistor RB is connected in series with electrode group B, and a drive voltage is applied by a power amplifier 11. The resistor RB is connected in series with the electrode group B, and a drive voltage is applied to the amplifier 11. The voltages of both ends of the resistors RA, RB are respectively detected by differential amplifiers 7, 12. When the phase difference of the input and the output is set to zero in the drive frequency by the amplifier 7, a band pass filter amplifier 8 and the amplifier 9, the oscillating frequency coincides with the resonance frequency of a drive unit. The output of the amplifier 8 is input to a 90 deg. phase shifter 10, and input to the amplifier 11. The amplifier 11 inputs the signal amplified to the prescribed level to the groups B. Thus, the traveling wave of the bending vibration is excited by the drive unit. |
