| 摘要 |
PURPOSE:To transport a sheet in stable manners by controlling the time phase difference between the ac voltages applied onto an electricity - mechanical energy converting means of each vibration body so that the phase difference detected by a phase difference detecting means becomes zero. CONSTITUTION:During the transport of a sheet, if the time phase at the spacial position of the progressive vibration wave formed on the first vibration body delays for the time phase at the spacial position of the progressive vibration wave formed on the second vibration body 5, the phase of the output signal of a piezoelectric element 2 for detecting the vibration state of the vibration body 1 delays for the phase of the output signal of a piezoelectric element 6 for detecting the vibration state of the vibration body 5. Therefore, the output signal of a phase difference detector 10 becomes a negative value, and the output signal of a low path filter 11 reduces. Therefore, the phase shift control signal of a voltage control type phase shifter 12 becomes negative, and the phase of the output signal of the phase shifter 12 is delayed, and the phase of the ac voltage applied onto the piezoelectric element divisions 7 and 8 of the vibration body 5 is delayed, and the time phase of the progressive vibration wave formed on the vibration body 5 is delayed. |
