Abstract: An image forming apparatus includes an endless intermediate transfer belt rotatably stretched over a plurality of rollers, and a detector to read a pattern on the intermediate transfer belt. One of the rollers includes a first portion disposed opposite an area on the intermediate transfer belt including a pattern passing position, and a second portion not including a pattern passing position. The first portion has a diameter smaller than that of the second portion thereof, and an elastic material is superimposed on the second portion only. The detector is disposed between a second roller disposed upstream of the first roller and a third roller disposed downstream of the first roller, and opposite the intermediate transfer belt.

Abstract: A transfer assembly includes a counter member having a contact face, an engagement/disengagement unit to engage and disengage the image carrying face of image carrying member and the contact face of counter member using a cam, a pressure device to apply force to a transfer nip between the image carrying face and contact face, and a recording medium feed device to feed the recording medium to the transfer nip. When the cam is at a first rotation position, the image carrying face and contact face are separated, and when the cam is at a second rotation position, the image carrying face and contact face contact. Before the recording medium enters the transfer nip, the cam rotates from the first rotation position toward the second rotation position. After the recording medium enters the transfer nip, the cam is at the second rotation position to press the image carrying face with the contact face.

Abstract: A transfer device includes a plurality of rollers, a rotatable intermediate transfer belt wound around and stretched between the rollers, a transfer member disposed in the inner loop of the belt and facing an image bearing member of an image forming apparatus disposed at an outer circumference of the belt, to transfer an image formed onto the surface of the image bearing member when contacting the intermediate transfer belt, and a position adjuster to adjust the position of the intermediate transfer belt at different positions relative to the image bearing member. The positions include a contact state in which the intermediate transfer belt applied with a predetermined tension contacts the image bearing member, a first separation state in which the tensioned intermediate transfer belt separates from the image bearing member, and a second separation state in which the intermediate transfer belt separates further away from the image bearing member.

Abstract: To provide an image forming apparatus capable of increasing the life of a rotating cam while preventing the occurrence of a shock jitter and transfer failure. The image forming apparatus is configured to execute a forced movement process for rotating the rotating cam to forcibly move a secondary transfer roller against a biasing force of a bias coil spring at a pre-entry timing prior to the entry of the front edge of a recording sheet into a secondary transfer position, and a pressure intensifying process for rotating the rotating cam to increase transfer pressure at a timing immediately after the entry of the front edge of the recording sheet into the secondary transfer position. As the forced movement process, the image forming apparatus executes, alternately, a first forced movement process for normally driving and rotating the rotating cam, and a second forced movement process for inversely driving and rotating the rotating cam, at a predetermined timing.

Abstract: A secondary transfer facing roller includes a roller part that has a through-hole penetrating in a rotary shaft line direction at a rotation center position, and a penetrating shaft member penetrating the through-hole of the roller part and spinning the roller part on a surface of the penetrating shaft member. Eccentric cams are fixed to both end regions that are not located in the roller part, so as to rotate integrally with the penetrating shaft member. A position regulating cam and an abutting roller form a gap between the intermediate transfer belt and the secondary transfer roller immediately before a transfer sheet enters a transfer nip part. While the gap is formed, current flows between the intermediate transfer belt and the secondary transfer roller via the position regulating cam and the abutting roller.