An image forming apparatus, comprising a conveyance path configured to convey an image receiving medium; a fixing device configured to fix an image formed on the image receiving medium; a first roller arranged at the downstream side of a conveyance direction of the image receiving medium with respect to the fixing device, the first roller comprising an axis; a second roller configured to face the first roller and an end thereof of which protrudes towards a central part of the conveyance path with respect to an end of the first roller at the central part of the conveyance path in a first direction substantially parallel to the axis; and a protrusion arranged at the second roller side to protrude towards the first roller side from the second roller side and a protruding amount of which is greater than that of the second roller.

A paper humidifying device includes: a pair of humidifying rollers configured to apply moisture to paper when the paper is sandwiched and conveyed; a water feed roller configured to supply moisture to an outer peripheral surface of the pair of humidifying rollers; a dewatering unit configured to wipe off moisture on the outer peripheral surface of the pair of humidifying rollers; a first drive unit configured to cause the water feed roller to be separated from or abut on the pair of humidifying rollers; a second drive unit configured to cause the dewatering unit to be separated from or abut on the pair of humidifying rollers; and a control unit configured to control the first drive unit and the second drive unit.

An image forming apparatus includes an image forming device to transfer an image to a recording sheet; a fixing device to feed the recording sheet and fix the image onto the recording sheet; a branching device to switch between an ejection path to eject the recording sheet fed downstream of the fixing device, to outside the apparatus, and a reversing path for duplex printing; and a back curl correction structure disposed in a sheet feeding path between the fixing device and the branching device. The back curl correction structure includes a drive roller; a driven roller; an auxiliary nip portion; a guide member; and a guide moving device to move the guide member to a first position and a second position depending on the condition of the recording sheet.

A fixing device has a flexible endless fixing member; a heater to heat the fixing member; a nip forming member to contact the fixing member directly or via a slide member; a pressure member, rotatably disposed opposite the fixing member and the nip forming member; and a back curl correction structure that includes a drive roller disposed on a side where a back curl appears in the recording sheet; a driven roller disposed opposite the drive roller; an auxiliary nip portion to feed the recording sheet; a guide member to guide the recording sheet fed out from the auxiliary nip portion to bend in a direction opposite a curled direction of the back curl of the recording sheet. A driving connection between the drive roller and the pressure member is performed by a connection between a drive roller side connection gear and a pressure member side connection gear.

An image forming apparatus includes a sheet tray, a feed roller, a transfer roller, a fuser, a conveying unit, and a controller configured to execute a normal process. The controller executes a particular process, when performing the single sided printing. The particular process is a process in which the controller is configured to execute a non-actual-printing process on a first surface of a first sheet, and then configured to execute the non-actual-printing on a first surface of a second sheet before executing an actual-printing process on a second surface of the first sheet. The non-actual-printing process is a process of conveying the sheet to the fuser without transferring the developer image onto the first surface of the sheet. The actual-printing process is a process of transferring the developer image onto the second surface of the sheet.

A curl correcting device includes a pair of fixed guides and a change-over guide. The pair of fixed guides composes a curved part of a conveyance path. The change-over guide is provided to be contactable with a sheet from a radial outer side of the curved part. An outer guide includes a pair of side pressing parts and a bulge part. The pair of side pressing parts is formed at both ends in a width direction. The bulge part is formed between the pair of side pressing parts so as to bulge toward the radial outer side of the curved part. The change-over guide is configured to move to a first correcting position when the sheet curled along the conveyance direction is conveyed through the conveyance path and to move to a second correcting position when the sheet curled along the width direction is conveyed through the conveyance path.

A paper correction apparatus B corrects a curl of a sheet S by passing the sheet S through curved paper conveying routes CCP1 and CCP2 whose curving amounts can be changed. The paper correction apparatus B is provided with a control unit B3 which sets the curving amounts of the curved paper conveying routes CCP1 and CCP2, and changes a sheet interval in accordance with the curving amounts which are set. By this configuration, it is possible to inhibit the productivity from being reduced due to paper correction during performing post-printing processes in a finisher which is located in the downstream side of the paper correction apparatus B.

A decurling device is provided on a downstream side with respect to a fixing device in a medium transporting direction and straightens a curl formed in a medium transported to the decurling device. The decurling device includes a bending unit extending across the medium transporting direction and having a guiding surface that guides a leading end of the medium, the leading end coming into contact with the guiding surface, the bending unit bending the medium in a decurling direction by using the guiding surface; an urging unit that urges the bending unit toward the medium; and a single or plural rotating members provided on a part of the guiding surface of the bending unit and rotating by coming into contact with the medium that is in contact with the guiding surface.

An image forming apparatus includes a sheet tray, a feed roller, a transfer roller, a fuser, a conveying unit, and a controller configured to execute a normal process. The controller executes a particular process, when performing the single sided printing. The particular process is a process in which the controller is configured to execute a non-actual-printing process on a first surface of a first sheet, and then configured to execute the non-actual-printing on a first surface of a second sheet before executing an actual-printing process on a second surface of the first sheet. The non-actual-printing process is a process of conveying the sheet to the fuser without transferring the developer image onto the first surface of the sheet. The actual-printing process is a process of transferring the developer image onto the second surface of the sheet.

An imaging system includes: an endless belt, a tensioning member, a heating member, a pressing member, a cleaning member. The endless belt conveys a printing medium. The tensioning member tensions the endless belt. The heating member heats the endless belt. The pressing member presses the endless belt against the heating member. The cleaning member is located outside the endless belt, between the tensioning member and the heating member, and presses the endless belt inwardly.