| 摘要 |
PROBLEM TO BE SOLVED: To drive the device positively with the simple circuit constitution even immediately after a power supply is turned on by changing the driving method of a piezoelectric transformer from the separate excitation method set at the time when the power supply is turned on to the self-excitation method. SOLUTION: A voltage, which drives a piezoelectric transformer 1 by the application on a primary side 1a of the piezoelectric transformer 1, is generated by a driving circuit 4 formed of an inductor 5 and a transistor 6, which is a switch element, and a power supply 23. The waveform voltage shown in (A) is applied on the base of the transistor 6. At this time, the energy, which is stored in the inductor 5 during the on-period of the transistor 6, is discharged by the resonance with the capacitance on the primary side of the piezoelectric transformer 1 when the transistor 6 is turned off. Thus, the voltage having the waveform shown in (B) is obtained. By the application of the voltage such as this, the piezoelectric transformer 1 generates the high voltage of sine waves on a secondary side 1b and makes the output current to flow to a cold-cathode fluorescent discharge lamp that is a load 2. |
