Patent ID: 8170433
Filing Date: 2012-05-01
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a rotatable photosensitive member; a charging member for electrically charging said photosensitive member; applying means for applying to said charging member a charging bias in the form of a DC voltage biased with an AC voltage; toner image forming means for forming a toner image on said photosensitive member charged by said charging member; setting means for setting a frequency of a first charging bias at a first frequency in a first mode in which said photosensitive member is rotated at a first speed to effect image formation and for setting a frequency of a second charging bias at a second frequency, different from the first frequency, in a second mode in which said photosensitive member is rotated at a second speed lower than the first speed to effect image formation; detecting means for detecting a current passing between said charging member and said photosensitive member during application of a test bias to said charging member; and adjusting means for adjusting the second charging bias on the basis of an output of said detecting means when said photosensitive member is rotated at the first speed and a test bias having the second frequency is applied to said charging member at the time of switching an image forming mode from the first mode to the second mode.