Patent ID: 7194215

Claim:
A cartridge detachably mountable to an image forming apparatus, which includes a voltage output device for outputting a plurality of alternating voltages of different levels to a charging member, a detector configured to detect a current flowing through an image forming member when an alternating voltage is outputted from the voltage output device to the charging member, and a controller configured to determine an alternating voltage to be outputted from the voltage output device to the charging member during image formation, and having a voltage determination mode in which an alternating voltage to be outputted to the charging member during image formation is determined by outputting the plurality of alternating voltages to the charging member, said cartridge comprising: said image-bearing member; said charging member configured to charge said image-bearing member; and a memory medium configured to store information relating to said cartridge, wherein said memory medium has a first storage area configured to store two or more pieces of control information for selecting one of the plurality of alternating voltages which are applied to said charging member with the voltage output device when executing the voltage determination mode before the apparatus is placed in a printable state, and a second storage area configured to store threshold information to change the control information, and wherein in said voltage determination mode, the control information and the threshold information are used together with a value detected by the detector in order to determine the alternating voltage to be outputted from the voltage output device to said charging member during image formation.