| 摘要 |
PROBLEM TO BE SOLVED: To eliminate instability in electric connection by shifting a characteristic frequency or higher-order characteristic frequency of an input/output lead terminal by at least a specified ratio from a driving frequency of a piezoelectric transformer. SOLUTION: A driving frequency of a piezoelectric transformer is shifted by at least 2% from a characteristic frequency or a higher-order characteristic frequency, for example, a 19th order characteristic frequency of lead terminal 8, 9. Then, the maximum stress developed in the lead terminals 8, 9 becomes lower than the breaking stress of the lead terminals 8, 9, and therefore the lead terminals 8, 9 are sufficiently tolerable to the stress developed at the driving of the piezoelectric transformer. Due to this structure, the lead terminals 8, 9 never resonate since the characteristic frequency or the higher-order characteristic of the lead terminals 8, 9 is shifted from the driving frequency of the piezoelectric transformer. Accordingly, there is no excessive stress developed by the resonance and a bad connection between the lead terminals or a disconnection is hardly caused.
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