| 摘要 |
PURPOSE:To boost the voltage accurately by means of a transformer and make it unnecessary to use a high-voltage power source or a high voltage resistance amplifier by converting the drive information of a piezoelectric element into a high-frequency region by modulating it. CONSTITUTION:The voltage waveform of a drive source information 1 on piezoelectric element 6 is amplitude-modulated by means of the output waveform of carrier source 3. Then, the voltage is boosted by transformer 4 and is fed to demodulator 5, and thereby the waveform of the voltage to be impressed on the piezoelectric element is obtained. For example, when the sensitivity of piezoelectric element 6 is 0.2mum/V and the required deflection of magnetic head 7 is + or -100mum, the required voltage to be impressed in + or -500V, and the transformation ratio of transformer 4 is selected accordinaly. Further, in order to drive accurately, the output voltage of demodulator 5 is divided, it is compared with the drive source information, and the modulation factor or output level of amplitude modulator 2 is changed by the difference voltage. |
