Patent ID: 7848679

Claim:
An image forming apparatus comprising: a rotatable electrophotographic photosensitive member; a contact charging member configured to charge a surface of the rotatable electrophotographic photosensitive member by contacting the rotatable electrophotographic photosensitive member; a charging current detection device configured to detect a current value that flows through the contact charging member; a pre-charge exposure device configured to remove a residual charge by exposing the surface of the rotatable electrophotographic photosensitive member to light before the rotatable electrophotographic photosensitive member is charged by the contact charging member; a standard exposure device adjusted to emit light of a predetermined light quantity and configured to expose the surface of the rotatable electrophotographic photosensitive member to the light; and a control device configured to control, in a non-image-forming period, the charging current detection device to detect a first current value which flows through the contact charging member when an area on the surface of the rotatable electrophotographic photosensitive member is recharged by the contact charging member, in a case where the rotatable electrophotographic photosensitive member which is charged by applying a predetermined voltage by the contact charging member is exposed by turning on the standard exposure device without turning on the pre-charge exposure device, to control, in the non-image-forming period, the charging current detection device to detect a second current value which flows through the contact charging member when an area on the surface of the rotatable electrophotographic photosensitive member is recharged by the contact charging member, in a case where the rotatable electrophotographic photosensitive member which is charged by applying a predetermined voltage by the contact charging member is exposed by turning on the pre-charge exposure device without turning on the standard exposure device, and to determine light quantity of the pre-charge exposure device based on the first current value and the second current value.