A fixing device includes a belt unit and an opposite member. The belt unit and opposite member are configured to, when a recording medium with a developer image transferred thereon passes through a nip region formed by the belt unit and opposite member, fix the developer image to the recording medium. The belt unit includes an endless belt, a heater group including a plurality of stacked heaters, and a holder that holds the heater group inside the belt.

A belt driving device to drive an endless belt, includes a drive roller and a suspension roller which extend in a first direction and face each other in a second direction. The belt driving device includes a steering roller located between the drive roller and the suspension roller in a tiltable manner. A pulley (or wheel) is located at an end portion of the steering roller. The belt driving device includes a link mechanism which presses the end portion of the steering roller to tilt the steering roller with the movement of the pulley (or wheel).

A belt unit includes a belt member to be caused to rotate, a stretching member that is rotatable about an axis and over which the belt member is stretched, and a rotatable member that is rotatable about the axis and relative to the stretching member and over which the belt member is stretched, the rotatable member including a receiving part configured to receive the belt member in an axial direction when the belt member is shifted in the axial direction.

There is provided a secondary transfer device for secondary-transferring a toner image primary-transferred on an outer peripheral surface of an endless annular intermediate transfer belt to a sheet at a predetermined secondary transfer position, the intermediate transfer belt having a predetermined width and being wound around a plurality of rollers and rotating, the secondary transfer device including: a pressure-releasing mechanism that displaces a secondary transfer roller to a pressing position and a separation position; a first drive that drives the pressure-releasing mechanism; a high-speed depressurization mechanism that temporarily depressurizes a nip pressure, at which the secondary transfer roller at the pressing position interposes and presses the intermediate transfer belt in a gap with respect to the opposite roller, when a leading end and a tailing end of a sheet pass between the secondary transfer roller and the intermediate transfer belt; and a second drive that drives the high-speed depressurization mechanism.

A fixing device includes a belt unit and an opposite member. The belt unit and opposite member are configured to, when a recording medium with a developer image transferred thereon passes through a nip region formed by the belt unit and opposite member, fix the developer image to the recording medium. The belt unit includes an endless belt, a heater group including a plurality of stacked heaters, and a holder that holds the heater group inside the belt.

A transport device includes a first belt member, a second belt member, a first roller, a second roller, a third roller, a fourth roller, a fifth roller, and a sixth roller. The second belt member is in contact with the first belt member to form a contact portion in cooperation with the first belt member. The first roller is capable of adjusting a tilt in a longitudinal direction of the first roller. The second roller is capable of adjusting a tilt in a longitudinal direction of the second roller. The third and fourth rollers are located adjacent to the first roller. The fifth and sixth rollers are located adjacent to the second roller. The third roller, the fourth roller, the fifth roller, and the sixth roller each have a uniform diameter in a longitudinal direction of the roller, and are disposed at positions other than the contact portion.

A drive force transmission mechanism includes a drive pulley, a driven pulley and an endless belt. The endless belt is wound around the drive pulley and the driven pulley and transmits a rotation of the drive pulley to the driven pulley. At least one of the drive pulley and the driven pulley has a protruding part protruding outwardly in a radial direction around an outer circumferential face of the drive pulley or the driven pulley. The belt is a nonmagnetic metal belt having an outer circumferential face and an inner circumferential face. The outer circumferential face has a surface roughness smaller than a surface roughness of the inner circumferential face.

An image forming apparatus includes: a belt unit including a transfer belt and a first memory that stores a first sheet conveying speed of the transfer belt; a second memory storing a first reference value and a second sheet conveying speed of the fixing unit a controller configured to: control at least one of the belt motor and the fixing motor to bring the speed difference between the sheet conveying speed of the transfer belt and the sheet conveying speed of the fixing unit closer to the first reference value by setting a rotational speed of the fixing motor based on the first reference value and a first speed difference between the first sheet conveying speed read from the first memory and the second sheet conveying speed read from the second memory.

A transport device includes a first belt member movably stretched, a second belt member, a first roller, a second roller, a third roller, a fourth roller, a fifth roller, and a sixth roller. The second belt member is in contact with the first belt member to form a contact portion in cooperation with the first belt member. The second belt member is movably stretched. The first roller stretches the first belt member and is capable of adjusting a tilt in a longitudinal direction of the first roller. The second roller stretches the second belt member and is capable of adjusting a tilt in a longitudinal direction of the second roller. The third roller stretches the first belt member and is located adjacent to the first roller and upstream of the first roller in a movement direction of the first belt member. The fourth roller stretches the first belt member and is located adjacent to the first roller and downstream of the first roller in the movement direction of the first belt member. The fifth roller stretches the second belt member and is located adjacent to the second roller and upstream of the second roller in a movement direction of the second belt member. The sixth roller stretches the second belt member and is located adjacent to the second roller and downstream of the second roller in the movement direction of the second belt member. The third roller, the fourth roller, the fifth roller, and the sixth roller each have a uniform diameter in a longitudinal direction of the roller, and are disposed at positions other than the contact portion.

A belt transport device includes an endless belt, multiple stretchers that stretch the belt, a corrector that displaces one of the multiple stretchers to correct a shift of the belt toward an edge portion of the belt in an axial direction of the belt, and a lubricant applicator that applies a lubricant to an inner surface of the belt at the edge portion of the belt in the axial direction when the belt has shifted toward the edge portion in the axial direction.