Image forming apparatus having charging member contactable to image bearing member.

摘要

An image forming apparatus includes an image bearing member (2); a charging member (1), contactable to the image bearing member (2), for charging the image bearing member (2); and a detector for detecting an electric current flowing through the charging member (1) when the charging member (1) changes a potential of a predetermined area of the image bearing member (2) from a potential Vl to which the image bearing member (2) is charged by the charging member to a potential V2 which is different from the potential V1. The state of the image bearing member such as its thickness can be detected by these measures.