Image forming apparatus with bias applying device for applying a charging bias to a charging roller and with a bias corrector

摘要

A bias corrector conducts a first bias correction calculation by performing first through third calculations. The first calculation compares a stored target charging current value to a first charging current value detected when a first charging bias was applied by a bias applying device. The second calculation is performed repeatedly to calculate a second charging bias based on the comparison result and then to compare the target charging current value to a second charging current value detected by the current detector when the second charging bias was applied by the bias applying device. The third charging bias is calculated based on the comparison result. A second bias correction calculation then is conducted to correct the charging bias obtained as a result of the first bias correction calculation based on photoconductor information detected by a photoconductor information detector.