Charger for charging an image holding member included in an image forming apparatus

摘要

When a resolution R (dpi) and a process speed (mm/sec) are determined, a voltage generating circuit 100 applies to a charging member a voltage consisting of an AC component having a frequency f which lies in a range having a maximum value and a minimum value determined by RS/25.4+/-120 (Hz), and a DC component superimposed on the AC component. The DC voltage should only be 0.5 kV to 1.2 kV while the peak-to-peak voltage of the AC component is selected to be slightly higher than the DC voltage. The peak-to-peak voltage should be higher than a discharge start voltage; a sufficient discharge occurs when it ranges from 0.9 kV to 1.3 kV. In this configuration, not only clear-cut character images are printed without regard to changes in environment, but also mesh images are free from moire and vertical stripes.