| 摘要 |
PROBLEM TO BE SOLVED: To provide a transformer which can perform the transformation with a high conversion efficiency even in case input voltage or load changes. SOLUTION: On the basis of the value of DC voltage V1 detected with an input voltage detecting circuit 21, an oscillating circuit 22 selects one resonance frequency out of a plurality of common frequency that a piezoelectric transformer 15 has, and outputs an oscillation signal of frequency geared to the selected resonance frequency in question to a drive circuit 13. Hereby, the rectangular wave voltage V2 of that frequency is supplied to the piezoelectric transformer 15 via a filter 14. COPYRIGHT: (C)2003,JPO
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