A fixing device includes a belt having a tubular shape and extending in a longitudinal direction, and having a longitudinal end, a drive roller to rotate the belt to convey a print medium between the drive roller and the belt, a bushing located at the longitudinal end of the belt, and a guide wall adjacent to the bushing. The belt is displaceable in the longitudinal direction relative to the bushing. The bushing includes a shoulder adjacent to the longitudinal end of the belt and a stem extending from the shoulder to an inside of the belt to support the belt. The guide guides the bushing to move in a direction opposite to a conveyance direction of the print medium when the belt moves toward the bushing. The stem of the bushing includes a convex portion that is in contact with an inner surface of the belt when the belt is displaced in the longitudinal direction.

A belt driving device includes a plurality of rollers, an endless belt, a contact surface, and a non-contact surface. The rollers include a driving roller that is rotationally driven. The endless belt is stretched between the rollers such that a predetermined tension is applied to the endless belt, and the endless belt protrudes from opposite end portions of the rollers in an axis direction of each of the rollers. The contact surface is formed at a first end portion of at least one of the rollers and comes in contact with the endless belt. The first end portion is located on a meandering direction side of the endless belt. The non-contact surface is formed at each of second end portions of the rollers and doesn't come in contact with the endless belt. The second end portions are located on a side opposite to the meandering direction of the endless belt.

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.

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.

A transfer device having a structure for preventing the meandering of a transfer belt, an image forming apparatus including a structure for preventing the meandering of a transfer belt. and a method for preventing meandering of the transfer belt. The image forming apparatus including a main body. The main body including an image forming member and a transfer device which transfers an image formed through the image forming member to a printing medium. The transfer device includes a frame, a driving roller, a backup roller being rotatably supported to the frame, a transfer belt to travel between the driving roller and the backup roller; and meandering prevention members located at both end portions of the backup roller to independently rotate. The meandering prevention members being driven by contact with the transfer belt to control tension of the transfer belt.

A belt driving device includes a plurality of rollers, an endless belt, a contact surface, and a non-contact surface. The rollers include a driving roller that is rotationally driven. The endless belt is stretched between the rollers such that a predetermined tension is applied to the endless belt, and the endless belt protrudes from opposite end portions of the rollers in an axis direction of each of the rollers. The contact surface is formed at a first end portion of at least one of the rollers and comes in contact with the endless belt. The first end portion is located on a meandering direction side of the endless belt. The non-contact surface is formed at each of second end portions of the rollers and doesn't come in contact with the endless belt. The second end portions are located on a side opposite to the meandering direction of the endless 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.

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 toner detection unit is configured by an LED that irradiates light toward an intermediate transfer belt, first and second light receiving elements that respectively receive specular reflection light and diffused reflection light of light irradiated toward the intermediate transfer belt from the LED, a circuit board, and a housing. The LED and the light receiving elements are mounted in a line on the circuit board. The housing is configured to guide, to the first light receiving element, the specular reflection light from a first region within an irradiation region on which light is irradiated from the LED on the intermediate transfer belt, and to guide, to the second light receiving element, the diffused reflection light from a second region which is different from the first region within the irradiation region.

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.