| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply device that can selectively output positive or negative voltage by only changing a drive frequency of a piezoelectric transformer. <P>SOLUTION: The power supply device comprises: two types of piezoelectric transformers 305 and 308 that change a step-up ratio according to a drive frequency and have different output characteristics to a drive frequency band; a first rectifier circuit 306 that is connected to a secondary side of one piezoelectric transformer 305 and outputs positive voltage; a second rectifier circuit 309 that is connected to a secondary side of the other piezoelectric transformer 308 and outputs negative voltage; and drive circuits 304 and 307 that apply AC voltage on the basis of the same drive frequency to two types of the piezoelectric transformers. The drive circuits 304 and 307 are switched between two drive frequency bands having different output characteristics. This allows to output the positive or negative voltage. Then, an OUT signal from a high voltage controller 206 controls the two drive circuits 304 and 307, so that the AC voltage having the same drive frequency is applied to the two types of the piezoelectric transformers. <P>COPYRIGHT: (C)2012,JPO&INPIT |
