| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the dispersion of the degree of polarization of a piezoelectric body, and to satisfactorily reach to the aimed degree of polarization by applying DC voltage to the piezoelectric body, measuring a current made to flow through the piezoelectric body resulting from the application of a DC current, and stopping the application of voltage when a measured current value reaches a set level. SOLUTION: A controller 8 calculates a voltage drop section in current- limiting resistors 41-4n from a current value detected by a current detector 7, and controls the inter-electrode voltage of the piezoelectric body, so as to be kept constant at all times by applying the voltage drop section to initial applied voltage. That is, applied voltage is determined on the basis of the calculation formula of applied voltage = initial voltage current value current limiting resistance. Thus, the dispersion of the degree of polarization among the piezoelectric bodies due to the dispersion of applied voltage can be reduced by keeping the voltage applied to each piezoelectric body constant at all times. Measuring time can be shortened, excess polarization due to the delay of measurement in the case of the polarization of a plurality of the piezoelectric bodies is prevented, and polarization can be controlled with high accuracy.</p> |
