| 摘要 |
PROBLEM TO BE SOLVED: To provide an inverter by which the brightness of a cold cathode tube is stabilized even if the power supply voltage of a piezoelectric transformer fluctuates. SOLUTION: The output of a voltage controlled oscillation circuit 11 oscillating at a frequency close to the resonance frequency of a piezoelectric transformer 16 is input to the piezoelectric transformer 16 via a drive circuit 12, and an output branched from the output voltage of the piezoelectric transformer 16 is fed back to the voltage controlled oscillation circuit 11 via a phase shift circuit 19, and a phase detection circuit 15. The oscillation frequency is controlled so that the output voltage of the piezoelectric transformer 16 becomes to a set value against the output voltage change of the drive circuit 12. |
