Power source device and image forming apparatus

An image forming apparatus comprising:

• an image forming portion configured to form a toner image on a recording material;
• a fixing portion including a heating member and configured to fix the toner image, unfixed and formed by the image forming portion;
• and
• a power source portion including
• a rectifying portion configured to fully rectify an AC voltage;
• a switching portion including a switching element and configured to apply a voltage to a load, fully rectified by the rectifying portion, by a switching operation of the switching element;
• a detecting portion configured to detect a zero-cross point of the AC voltage;
• a control portion configured to control the switching operation of the switching portion;
• and
• a filter portion including a capacitor, provided between the rectifying portion and the switching portion and configured to absorb a switching noise generated in the switching portion,
• wherein the control portion configured to control the switching portion so as to execute a discharge operation to discharge the capacitor before starting the switching operation from a stop state of the switching operation and so as to start the switching operation when the zero-cross point is detected by the detecting portion, and
• wherein an electric power outputted from the switching portion during the discharge operation is smaller than an electric power outputted from the switching portion during the switching operation.