The belt conveyance device includes an endless belt member, and a steering roller that stretches the belt member and has a tiltable rotation axis. The steering roller includes a roller that slides on the belt member and rubbing members that rub against the belt member at both ends of the roller. One or a plurality of recessed portions is formed in the surface of each rubbing member in an area where the surface of the rubbing member is opposed to an inner surface of the belt member.

A color printing unit includes one printing station for each color along with one anode roller. A continuous transfer belt is guided over a deflection roller and a control roller. One or more sensors measure a property of reference markings printed on the transfer belt. A control device for controlling and adjusting the transfer belt acts on the control roller through an actuating motor as a function of the detected properties of the reference markings. The one or more sensors are arranged in the area of the control roller for the transfer belt, by which an additional tension roller saves costs and space. During the measurement, at least for the period in which the printed reference markings pass under the one or more sensors, relative movements between the one or more sensors and the control roller are ruled out.

A transfer unit includes an endless belt member, belt support rollers, a frame, a meandering detecting sensor, an alignment adjusting mechanism, and a conveyance guide disposed on a downstream side of the belt member with respect to a recording-medium conveyance direction. The alignment adjusting mechanism, based on a detection result of the meandering detecting sensor, causes one end portion of a downstream-side belt support roller of the belt support rollers which is adjacent to the conveyance guide to move along the recording-medium conveyance direction. The alignment adjusting mechanism causes a first end portion of the conveyance guide disposed on a same side as the one end portion of the downstream-side belt support roller to move following movement of the one end portion of the downstream-side belt support roller, and thereby maintains a distance between the belt member and the conveyance guide constant.

An image forming apparatus includes a plurality of image forming portions; a rotatable endless belt; a plurality of stretching rollers including an inner roller and a steering roller; an outer roller; a steering mechanism; a position changing mechanism; and a controller. In a case that a changing operation for changing a position of the inner roller is performed by the position changing mechanism during execution of a job for forming the toner images on a plurality of recording materials, the controller controls the steering mechanism so that a tilting operation for tilting the steering roller in a predetermined amount in interrelation with the changing operation is executed.

An image forming apparatus includes an image transfer unit configured to transfer an image formed on an image carrier to a sheet, according to a transfer control parameter, and a transfer control unit. The transfer unit is configured to set the transfer control parameter to a first value when a first portion of the image is being transferred to a first area of the sheet and to a second value when a second portion of the image is being transferred to a second area of the sheet transfers an image formed on an image carrier to a sheet.

The belt conveyance device includes an endless belt member, and a steering roller that stretches the belt member and has a tiltable rotation axis. The steering roller includes a roller that slides on the belt member and rubbing members that rub against the belt member at both ends of the roller. One or a plurality of recessed portions is formed in the surface of each rubbing member in an area where the surface of the rubbing member is opposed to an inner surface of the belt member.

An image forming apparatus includes a plurality of image forming portions, a rotatable endless belt, a plurality of stretching rollers including an inner roller, an outer roller, a position changing mechanism, and a controller. During execution of a job for forming first toner images on a first recording material and second toner images on a second recording material subsequent to the first recording material, in a case that a changing operation for changing the position of the inner roller by the position changing mechanism after the first toner images are formed on the first recording material and before the second to toner images are transferred onto the second recording material is executed, a registration adjusting image is formed between the first toner images and the second toner images.

A belt rotating device includes: a meandering correction roller that is rotatably supported within a support frame and is one of a plurality of rollers that stretch an endless belt; a supporting portion that is provided at the support frame and supports a rotating shaft of the meandering correction roller so as to be able to incline the rotating shaft of the meandering correction roller in a one direction; a collar member that is provided on the rotating shaft of the meandering correction roller, contacts the side end of the endless belt in which meandering has occurred, and moves in an axial direction; and an inclination guide portion that is supported by the support frame and has an inclined surface downward and inclined with respect to the shaft of the meandering correction roller, in a position in which the contact portion of the collar member contacts the inclination guide portion.

A belt transporting device includes a belt; first and second adjustment members provided at two respective ends of a tension roller in a belt width direction orthogonal to a direction of rotation of the belt, the first and second adjustment members each being movable by receiving a force from the belt; and a link member that interlocks the movement of the first adjustment member and the movement of the second adjustment member. If the belt is laterally shifted in the belt width direction, one of the first and second adjustment members moves by receiving a force from the belt while the other is moved by the link member such that the tension roller is tilted with respect to a driving roller.

A belt rotating device includes: a meandering correction roller that is rotatably supported within a support frame and is one of a plurality of rollers that stretch an endless belt; a supporting portion that is provided at the support frame and supports a rotating shaft of the meandering correction roller so as to be able to incline the rotating shaft of the meandering correction roller in a one direction; a collar member that is provided on the rotating shaft of the meandering correction roller, contacts the side end of the endless belt in which meandering has occurred, and moves in an axial direction; and an inclination guide portion that is supported by the support frame and has an inclined surface downward and inclined with respect to the shaft of the meandering correction roller, in a position in which the contact portion of the collar member contacts the inclination guide portion.