| 摘要 |
PROBLEM TO BE SOLVED: To obtain a piezoelectric transformer which is suitable for small-sized power source circuit, etc., requiring low output impedances and has a superior piezoelectric characteristic and a strong mechanical strength. SOLUTION: A piezoelectric transformer is constituted in such a way that power generating sections 3 and a driving section 2, each of which is formed by alternately laminating piezoelectric ceramic layers polarized in the thickness direction and electrode layers upon another, are arranged in the longitudinal direction, and the adjacent electrode layers are alternately connected at every other layer through external electrodes so that the polarities of the electrode layers may become opposite to each other. In addition, insulating sections 4 composed of an unpolarized piezoelectric ceramic having a width of 0.2-3 mm are respectively provided in the areas between the driving section 2 and power generating sections 3. The mean particle diameter of the crystals contained in the apparent crystalline structure in the observed cross-section image of the piezoelectric ceramic is <=1μm, and the mean particle diameter of the crystal grains contained in the >=80% area of the apparent crystalline structure is <=1μm.
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