| 摘要 |
An AC/DC converter of the present invention includes a transformer implemented by a piezoelectric transformer. Power fed from a commercially available power source (14) is converted to a DC voltage by rectification and smoothing. The DC voltage is transformed to a high frequency (about 100 kHz) pulse voltage by switching FETs (Field Effect Transistors) (5) and (6). The pulse voltage is applied to the input of a piezoelectric transformer (9). The transformer (9) has its vibration mode and dimension selected such that the resonance frequency of the transformer is substantially identical with the frequency of the above pulse wave. A high frequency AC voltage is produced from the output side of the transformer (9). The AC voltage is transformed to a DC voltage by rectification and smoothing and then fed to a load resistor (13). The piezoelectric transformer is easy to miniaturize, compared to an electromagnetic transformer. The entire AC/DC converter can therefore be reduced in size.
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