The present invention provides a fixing device including a flexible cylindrical rotary member and an inner-surface opposing portion that opposes an inner surface of the rotary member at an end portion of the rotary member in a generatrix direction. The inner-surface opposing portion moves upstream in a recording material conveying direction in accordance with lateral shift of the rotary member in the generatrix direction. This restricts the lateral shift of the rotary member.

An image forming apparatus includes an image bearing member, an image forming unit, a belt conveying device including an intermediate transfer belt, a pair of restriction portions provided in the belt conveying device, and restriction engagement portions. The image forming unit forms a toner image on the image bearing member and the toner image is transferred to the intermediate transfer belt. The pair of restriction portions and the restriction engagement portions cooperate to restrict an orientation of the intermediate transfer belt. One restriction portion of the pair of restriction portions is supported to be movable to a first position where at least a part of the one restriction portion is placed outside a stretching area defined by the intermediate transfer belt in a stretched state, and a second position where the one restriction portion is inside the stretching area as viewed from a width direction of the intermediate transfer belt.

An image forming apparatus includes an image bearing member, an image forming unit, a belt conveying device including an intermediate transfer belt, a pair of restriction portions provided in the belt conveying device, and restriction engagement portions. The image forming unit forms a toner image on the image bearing member and the toner image is transferred to the intermediate transfer belt. The pair of restriction portions and the restriction engagement portions cooperate to restrict an orientation of the intermediate transfer belt. One restriction portion of the pair of restriction portions is supported to be movable to a first position where at least a part of the one restriction portion is placed outside a stretching area defined by the intermediate transfer belt in a stretched state, and a second position where the one restriction portion is inside the stretching area as viewed from a width direction of the intermediate transfer belt.

The present invention provides a fixing device including a flexible cylindrical rotary member and an inner-surface opposing portion that opposes an inner surface of the rotary member at an end portion of the rotary member in a generatrix direction. The inner-surface opposing portion moves upstream in a recording material conveying direction in accordance with lateral shift of the rotary member in the generatrix direction. This restricts the lateral shift of the rotary member.

In a fixing device, a pressure unit is pressed toward a roller by an arm, to form a nip region. The pressure unit includes a belt configured to contact the roller in a nip region, a pressure pad configured to press the belt in combination with the roller, and a side guide including an end guide surface configured to guide a side end of the belt, and a stay configured to support the pressure pad. A supporting member is located on an outer side of the side guide that is opposite to an inner side on which the end guide surface faces. The supporting member is held between the stay and the arm, the supporting member comprising a contact surface which contacts the side guide and on which the side guide is swayably supported.

The belt conveyance device includes a plurality of rollers, a belt, a meandering correction part, and an adjustment part. The rollers are disposed at intervals each other and rotate around axes. The belt is disposed around the plurality of rollers and travels. The meandering correction part shifts one end portion in an axial direction of a tension roller included in the plurality of rollers in a radial direction within a predetermined range to correct a meandering of the belt. The adjustment part shifts the other end portion in the axial direction of the tension roller in the radial direction such that a position of the one end portion of the tension roller is variable under a state where the meandering of the belt is corrected.

A fixing apparatus includes a fixing belt, a pressing roller configured to form a nip by pressing the fixing belt and rotate the fixing belt, a bush configured to guide an edge of the fixing belt, and a meandering adjustment member configured to move a rotation shaft of the pressing roller in a direction perpendicular to an axis direction of the pressing roller. The fixing apparatus can be provided to an image forming apparatus.

An imaging system includes: a steering roller located between a first belt roller and a second belt roller, that is inclinable around a fulcrum; and a sensor to detect an amount of displacement of the steering roller due to an inclination of the steering roller. A controller may output a command signal when the amount of displacement of the steering roller exceeds a reference value.

A belt driving device includes plural rotating members around which a belt member extends, each rotating member rotating about a rotating shaft; and contact members disposed at both sides of the belt member in a width direction. The rotating members include a first rotating member, having a dimension less than a width of the belt member in a direction of the rotating shaft. Each contact member has a first contact point at which the contact member contacts the belt member and a second contact point closer to a corresponding one of the end portions in the width direction than the first contact point and at which the contact member contacts the belt member such that an angle between the contact member and the rotating shaft at the second contact point is greater than an angle between the contact member and the rotating shaft at the first contact point.

In a fixing device, a pressure unit is pressed toward a roller by an arm, to form a nip region. The pressure unit includes a belt configured to contact the roller in a nip region, a pressure pad configured to press the belt in combination with the roller, and a side guide including an end guide surface configured to guide a side end of the belt, and a stay configured to support the pressure pad. A supporting member is located on an outer side of the side guide that is opposite to an inner side on which the end guide surface faces. The supporting member is held between the stay and the arm, the supporting member comprising a contact surface which contacts the side guide and on which the side guide is swayably supported.