초록 ▼

Disclosed is 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 piezoel

Disclosed is 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. The circuit has: an excessively-small current detection means that outputs excessively-small current signal when load current flowing through the load is smaller than a predetermined value; a stopping means that stops the operation of the booster circuit when the excessively-small current signal is output; and a delaying means that sets a delay time according to the level of the output voltage. The stopping means determines the execution or inexecution of the operation according to the existence of the excessively-small current signal when the delay time passes.

대표청구항 ▼

[ What is claimed is:] [1.] 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

[ What is claimed is:] [1.] 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.