| 摘要 |
PURPOSE:To control exactly a displacement quantity of a piezoelectric element by detecting the displacement quantity of the piezoelectric element, feeding back this value and displacing the piezoelectric element to a prescribed position. CONSTITUTION:A signal for displacing a bimorph 10 by a prescribed quantity is outputted from a signal source 11. A driving voltage detecting circuit 18 detects a driving voltage. Also, a resistance 14 detects a driving current, and outputs it to an integration circuit 16. The circuit 16 outputs a value corresponding to a total charge which has been accumulated in the bimorph 10. A subtraction circiut 20 subtracts an output signal value of the circuit 18 from an output signal value of the circuit 16 and derives an actual displacement quantity of the bimorph 10. Subsequently, this value is fed back to a driving circuit 13 through a phase compensating circuit 22. Therefore, the displacement quantity of the bimorph 10 is controlled so as to become a prescribed value. In this way, the displacement quantity of the bimorph 10 can be controlled exactly. |
