Image forming apparatus using common AC voltage source for plural charging members and photosensitive members

摘要

An image forming apparatus includes photosensitive drums; drum charging members, an AC voltage source for outputting an AC voltage commonly to at least two of the charging members; AC voltage control devices for the charging members; variable resistors connected between the AC voltage source and the at least two charging members, respectively; a use situation detecting unit for detecting use situations of the drums, respectively; and an adjusting unit for adjusting electric resistances of the variable resistors, respectively. The adjusting unit adjusts the electric resistances of the resistors in accordance with the detection results of the use situation detecting unit such that the discharge currents applied to the at least two charging members are within predetermined ranges, respectively.

主权项

1. An image forming apparatus comprising:
a plurality of photosensitive members; a plurality of charging members, provided for said photosensitive members, respectively, for electrically charging said photosensitive members by being supplied with charging voltages each comprising a component of a DC voltage and a component of an AC voltage; an AC voltage source for outputting an AC voltage commonly applied to at least two of said charging members; control means for controlling the AC voltages applied to said at least two charging members; variable resistors connected between said AC voltage source and said at least two charging members, respectively; use situation detecting means for detecting use situations of said photosensitive members, respectively; and adjusting means for adjusting electric resistances of said variable resistors, respectively, wherein said adjusting means adjusts the electric resistances of said variable resistors in accordance with detection results of said use situation detecting means such that discharge currents flowing between said at least two charging members and said photosensitive members charged by said at least two charging members are within predetermined ranges, respectively.