Power supply unit in image forming apparatus

Abstract

A power supply unit in an image forming apparatus is provided. The power supply unit includes a piezoelectric transformer, an output voltage detecting circuit which detects the output voltage of the piezoelectric transformer, a comparator which receives an output voltage setting signal, together with an output voltage detecting signal fed back from the output voltage detecting circuit, to compare the output voltage setting signal and the output voltage detecting signal, and a driving frequency supplying circuit which generates the driving frequency of the piezoelectric transformer in accordance with a comparison result by the comparator, and supplies the resultant driving frequency to the piezoelectric transformer. The time constant of the output voltage setting signal is longer than the time constant of the output voltage detecting circuit.

Dependencies are inferred from the claim text.