| 摘要 |
PURPOSE:To correct the displacement of a bimorph piezoelectric element from a deflection with respect to the prescribed deflecting voltage by feeding back a voltage which correspond to the displacement to the bimorph element when the element is deflected to the position displaced from the deflection. CONSTITUTION:When the deflecting voltage of a tracking signal source 60 is 0V, in case that a bimorph piezoelectric element 10 is moved by DELTAD by the initial state, the deflection DELTAD is detected by a displacement sensor 30, and a voltage becoming DELTAV to match the displacement DELTAD is outputted by a comparator 50. The voltage DELTAV is inputted as a voltage V through a DC amplifier 70 to a mixer 80. In the mixer 80, the voltage is inverted and is inputted as -V. The voltage outputted from the mixer 80 becomes the deflecting voltage of the value applied with the deflecting voltage 0(V) and the voltage -V(V) from the tracking signal source 60, and a deflecting voltage for providing the displacement of the inverted direction of the sign is applied as the displacement of DELTAD to the element 10. Accordingly, the element 10 is returned to its initial state. |
