| 摘要 |
PROBLEM TO BE SOLVED: To carry out longitudinal polarization enough by applying a voltage between an output electrode and an input electrode formed in an opposite surface thereof and performing longitudinal polarization for a part which an input electrode of a piezoelectric ceramic board is not formed. SOLUTION: Input electrodes 11, 12 are formed in rear and front surfaces of one longitudinal end side of a piezoelectric ceramic board 10 extending over about half a length thereof. An output electrode 13 is formed to a strip in an edge face on the other side of the same surface of the input electrode 11. A DC voltage is applied between the input electrode 12 and the output electrode 13 and a part which an input electrode is not formed is subjected to longitudinal polarization. Successively, a DC voltage is applied between the input electrodes 11, 12 and polarization is carried out in a thickness direction of an input electrode. It is necessary that a thickness of a piezoelectric ceramic bard is at most 1/10 to a length of a part which is polarized, namely, a length of a part which an input electrode is not formed. Therefore, longitudinal polarization can be carried out enough. |
