| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly versatile control circuit having an excellent constant-voltage outputting characteristic. SOLUTION: A detecting resistor 12 and a rectifier circuit 15 convert the load current of a load 13 when the output voltage of a piezoelectric transformer 1 is applied across the load 13 into a voltage and an A/D conversion circuit 22 digitizes the voltage. An arithmetic processing circuit 24 compares the digitized detected voltage with a preset reference value in accordance with a program stored in a memory 23 and, when the voltage is smaller than the reference value, instructs a timer circuit 21 to lower an oscillation frequency to a drive circuit 12. When the detected voltage is smaller than the reference value, the circuit 24 instructs the circuit 21 to raise the oscillation frequency. The drive circuit 12 drives the transformer 1 in accordance with the oscillation frequency of a signal obtained from the timer circuit 21. |
