Patent ID: 7978991

Claim:
An image forming apparatus including an image carrier, the image forming apparatus comprising: a charging member disposed in contact with or close to the image carrier so as to charge the image carrier, said charging member having a resistance value which varies according to at least one of an environmental temperature or an environmental humidity of the image forming apparatus; a high voltage generating circuit that applies an oscillating voltage to the charging member, wherein the oscillating voltage comprises a DC voltage and an AC voltage superimposed on each other; a voltage control portion that controls the high voltage generating circuit such that a peak-to-peak voltage value of the AC voltage reaches a target voltage value; and the voltage control portion having an initial voltage adjusting portion that is configured to perform a target voltage setting operation to set the target voltage value upon determination that power to the image forming apparatus is turned on and upon determination that the image forming apparatus returns from a power saving mode, the target voltage setting operation including: performing a first determination determining if a predetermined environmental condition exists, said predetermined environmental condition including at least one of an environmental temperature or an environmental humidity of the image forming apparatus; performing a calibration process setting the target voltage value; performing a second determination determining if the target voltage value is greater than or equal to a predetermined voltage value; and interrupting an image forming process being performed to suspend the image forming process and then again performing the calibration process to set the target voltage value in response to both the first determination and the second determination being positive.