Patent ID: 7616909

Claim:
An image forming apparatus comprising: an intermediate transfer member; a primary transfer member configured to primarily transfer an image formed on an image carrier onto a surface of the intermediate transfer member; a secondary transfer member configured to secondarily transfer the image on the intermediate transfer member onto a transfer material, the secondary transfer member being in contact with the intermediate transfer member; and contact members attached to outer ends of the secondary transfer member in the axial direction, wherein a relation A>B>C is satisfied, where A is a width of the intermediate transfer member, B is a width of the secondary transfer member, and C is a width of the transfer material that passes between the intermediate transfer member and the secondary transfer member, wherein the surface of the intermediate transfer member includes an image forming area, a contact area, and a patch-pattern forming area, such that the patch pattern forming area is not contacted by the secondary transfer member, wherein the contact area is formed along edges of the intermediate transfer member, wherein the patch pattern forming area is located between the contact area and the image forming area, wherein the contact members are configured to press against the contact area of the intermediate transfer member, and wherein the image forming apparatus further comprises an optical detector configured to detect a patch pattern formed in the patch-pattern forming area by the primary transferring member.