Patent ID: 8639141

Claim:
An image forming apparatus comprising: an image bearing member for bearing a toner image; a rotatable intermediary transfer member onto which the toner image is to be primary-transferred from said image bearing member; a contact member movable toward and away from said intermediary transfer member; a voltage applying unit for applying a voltage to said contact member; a current detecting circuit for detecting a current passing through said contact member to which the voltage is applied by said voltage applying unit; and a control portion for effecting control so that said contact member is in contact with or separated from said intermediary transfer member, wherein said control portion is capable of executing an operation in a measuring mode in which a contact time required to bring said contact member into contact with said intermediary transfer member is calculated by applying an initial voltage to said contact member, then by outputting a contact instruction signal to move said contact member from a separated state so as to be in contact with said intermediary transfer member, and then by measuring a time from output of the contact instruction signal until said current detecting circuit detects a predetermined current value.