Patent ID: 6151232
Filing Date: 2000-11-21
Classification: H02M,H05B

Abstract:
A power supply circuit for boosting drive voltage by a booster circuit, inputting the boosted voltage to the primary side of a piezoelectric transformer, and driving a load with an impedance of large temperature dependency by output voltage generated at the secondary side of the piezoelectric transformer, comprising:an excessively-small current detection means that outputs excessively-small current signal when load current flowing through said load is smaller than a predetermined value;a stopping means that stops the operation of said booster circuit when said excessively-small current signal is output; anda delaying means that sets a delay time according to the level of said output voltage;wherein said stopping means determines the execution or inexecution of said operation according to the existence of said excessively-small current signal when said delay time passes.