Patent ID: 7693437

Claim:
An image forming apparatus comprising: a rotatable image bearing member having a photosensitive layer; toner image forming means for forming a toner image on said image bearing member, said toner image forming means being capable of forming a detection toner image on a part of said image bearing member along a direction in which the rotational axis of said image bearing member extends; detecting means for optically detecting the detection toner image formed on said image bearing member; control means for controlling a toner image forming condition of said toner image forming means on the basis of a result of detection of said detecting means; a transfer member for electrostatically transferring a toner image from said image bearing member onto a transfer material at a transfer region; and voltage applying means for applying to said transfer member when said detection toner image passes the transfer region, a predetermined voltage which has the same polarity as a charge polarity of toner and which is such a voltage that the potential difference between said transfer member and said image bearing member in an area of said image bearing member for the formation of the detection toner image after passing said detecting means and before reaching the transfer region is not less than a discharge threshold and that the potential difference between said transfer member and said image bearing member in an area of said image bearing member outside the area for formation of the detection toner image is less than the discharge threshold.