Patent ID: 7305196

Claim:
An apparatus for controlling a high voltage in an image forming apparatus using the high voltage with a high alternating current voltage superimposed on a high direct current voltage, comprising: a high alternating current voltage output unit outputting the high alternating current voltage; a high direct current voltage output unit outputting the high direct current voltage; and a controlling unit controlling the high alternating current voltage output unit and the high direct current voltage output unit such that the high alternating current voltage is output before the high direct current voltage when the high voltage is required for printing, wherein the controlling unit includes: a peak-to-peak controller generating an AC_Vp-p signal for controlling a peak-to-peak voltage ACVpp of the high alternating current voltage output from the high alternating current voltage output unit; a duty controller generating an AC_Vduty signal for controlling a duty of the high alternating current voltage; an enable signal generator generating an AC_Enable signal for outputting the high alternating current voltage; a direct current pulse width modulation controller generating a DC_PWM signal for controlling the high direct current voltage output from the high direct current voltage output unit by using a pulse width modulation; and a signal processor controlling an operating sequence of each of the peak-to-peak controller, the duty controller, the enable signal generator, and the direct current pulse width modulation controller as well as the AC_Vp-p signal, AC_Vduty signal, the AC_Enable signal, and the DC_PWM signal respectively generated by each of the same, wherein the signal processor controls the peak-to-peak controller and the duty controller such that the AC_Vp-p signal and the AC_Vduty signal can be generated before the DC_PWM signal.