Switching power supply device and image forming apparatus with switching power supply device

摘要

A current resonance type switching power supply device controls an ON/OFF operation of two switching elements according to an amount of change in voltage of a current resonance capacitor.

主权项

1. A switching power supply device comprising:
a transformer; a first switching element and a second switching element connected to a primary winding of the transformer, the first switching element and the second switching element being connected in series; a capacitance element connected to the primary winding in series; a control unit configured to drive the first switching element and the second switching element alternately; a detection unit configured to detect a voltage of the capacitance element; a first generation unit configured to generate a first pulse signal according to the voltage of the capacitance element detected by the detection unit; and a second generation unit configured to generate a second pulse signal according to a driving state of the first switching element and the second switching element, wherein the control unit is configured to control the first switching element and the second switching element so as to provide a period in which the first switching element and the second switching element are turned off, when a state where a first timing for switching a level of the first pulse signal from high to low is earlier than a second timing for switching a level of the second pulse signal from high to low is changed to a state where the first timing is later than the second timing.