| 摘要 |
PURPOSE:To prevent a crack from being generated by respectively executing the polarization processing of piezoelectric ceramics before and after the piezoelectric ceramics is adhered with a diaphragm. CONSTITUTION:Before piezoelectric ceramics 2 is adhered with a diaphragm 1, a high voltage is impressed to the piezoelectric ceramics and the first polarization processing is executed. With accompanying this polarization processing, a shape deformation is generated and the piezoelectric ceramics 2 is extended in a thickness direction and contracted in a radius direction on the other hand. However, since the polarization processing is executed before the piezoelectric ceramics is adhered with the diaphragm 1, distortion is not generated in the internal part of the piezoelectric ceramics 2. Next, the high voltage is impressed again to this piezoelectric ceramics 2 and the second polarization processing is executed. By the impression of the high voltage at the time of this polarization processing, the deformation change is generated in the piezoelectric ceramics 2. However, this piezoelectric ceramics 2 is once deformed at the time of the first polarization processing and deformation quantity is small at the time of the second polarization processing. Thus, the crack, which is caused by the deformation, can be prevented from being generated. |
