| 摘要 |
A drive circuit for a piezoelectric transformer includes a master block 24 having a drive frequency control circuit for controlling the frequency of a drive voltage for a piezoelectric transformer, at least one slave block 25 receiving an output of the above mentioned drive frequency control circuit and having a drive voltage control circuit for controlling a peak value of a drive voltage for a piezoelectric transformer, a circuit for PWM-modulating the drive voltages applied to the piezoelectric transformers, and driving the drive voltages in the same phase, and a circuit for suppressing a harmonic component of a light adjusting frequency included in the drive voltages for the piezoelectric transformers. With this arrangement, when a plurality of cold cathode tubes are driven by using piezoelectric transformer inverters, it is possible to eliminate the limit in the number of tubes lighted and the inclination of the brightness, and to prevent a flickering and the generation of an audible sound.
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