Patent ID: 8213824

Claim:
An image forming apparatus, comprising: a DC (direct current) power controller to convert and output a first PWM (pulse width modulation) signal into a switching waveform signal; a DC (direct current) power transformer to transform the switching waveform signal output from the DC power controller; a rectifier to rectify the output power transformed by the DC power transformer into DC power; first through fourth DC supplies to adjust and output the DC power rectified by the rectifier such that the DC power is adjusted to a respective predetermined level; first through fourth AC (alternating current) power controllers to convert and output a second PWM signal provided from the engine controller into switching waveform signals; first through fourth voltage transformers to transform the switching waveform signals output from the first through fourth AC power controllers and to combine the transformed AC powers and the adjusted DC powers having predetermined levels of the first through fourth DC supplies, respectively; and first through fourth developing units to receive the combined AC and DC powers from the respective first through fourth DC supplies and each expel a developer based on the received combined AC and DC powers, wherein each of the first through fourth DC supplies is supplied with the rectified DC power and performs a switching operation using a third PWM signal and the supplied DC power to adjust a power level of the DC power.