Power converting device and image forming apparatus employing the same

An image forming apparatus comprising:

• an image forming unit configured to form an image on a recording medium;
• and
• a power converting device comprising:
• a rectifier bridge configured to pulsate an AC voltage to generate a pulsating voltage,
• a first smoothing capacitor configured to smooth the pulsating voltage to generate a DC voltage,
• a primary winding connected to the first smoothing capacitor,
• a switch circuit configured to switch the DC voltage supplied from the first smoothing capacitor to the primary winding,
• a secondary winding excited with a magnetic field generated with the primary winding,
• a second smoothing capacitor configured to smooth a voltage generated with the secondary winding and supply electric power to the image forming unit,
• a first discharge circuit comprising:
• a first discharge resistor configured to discharge electric charges remaining on the first smoothing capacitor, and
• a first switch element configured to release the first discharge resistor from the first smoothing capacitor if the AC voltage is supplied and to connect the first discharge resistor to the first smoothing capacitor if the AC voltage is not supplied and the electric charges remain on the first smoothing capacitor, and
• a second discharge circuit comprising:
• a second discharge resistor configured to discharge electric charges remaining on the second smoothing capacitor, and
• a second switch element configured to release the second discharge resistor from the second smoothing capacitor if the AC voltage is supplied and to connect the second discharge resistor to the second smoothing capacitor if the AC voltage is not supplied and the electric charges remain on the second smoothing capacitor.

A power converting method, comprising:

• pulsating an AC voltage to generate a pulsating voltage;
• smoothing the pulsating voltage to generate a DC voltage using a first smoothing capacitor;
• switching the DC voltage supplied by the first smoothing capacitor to a primary winding;
• discharging electric charges remaining on the first smoothing capacitor using a first discharge resistor;
• and
• releasing the first discharge resistor from the first smoothing capacitor if the AC voltage is supplied and connecting the first discharge resistor to the first smoothing capacitor if the AC voltage is not supplied and the electric charges remain on the first smoothing capacitor.