Patent ID: 7840153

Claim:
A image forming apparatus, comprising: a plurality of DC-powered units; a fusing unit; a main power supply unit configured (1) to convert an AC power source into an AC power and a first DC power, (2) to provide the AC power to the fusing unit, and (3) to provide the first DC power to the plurality of DC-powered units; a supplemental power supply unit configured to accumulate the AC power from the AC power source and to provide a second DC power to the plurality of DC-powered units for a predetermined period, the supplemental power unit comprising a DC-to-DC converter configured to convert an accumulated DC power to the second DC power; and a voltage detector configured to detect a voltage of the accumulated DC power; and a controller configured (1) to reduce the AC power to be provided to the fusing unit, (2) to stop the second DC power to be supplied to the plurality of DC-powered units, and (3) to start the first DC power to be supplied to the plurality of DC-powered units, when the voltage detector detects that the accumulated DC power has dropped below a predetermined level.