A sheet feeding apparatus includes a first drive roller and a second drive roller disposed downstream of the first drive roller and configured to rotate at a peripheral speed greater than a peripheral speed of the first drive roller. The first drive roller includes a drive shaft and a roller portion. The roller portion is configured to contact the sheet and is movable relative to the drive shaft in an axial direction and a rotation direction of the drive shaft. One of the drive shaft and the roller portion of the first drive roller includes a protrusion protruding toward the other one of the drive shaft and the roller portion. The other one of the drive shaft and the roller portion of the first drive roller includes a recessed portion. The recessed portion includes a peripheral wall that defines an opening such that the protrusion is positioned in the opening.

An image forming apparatus includes a photosensitive drum, a fixing unit including a fixing roller, a sheet ejection tray, a switchback roller, a re-feeding roller, a first frame, a second frame, a first motor, a first transmission mechanism, a second motor, and a second transmission mechanism. The switchback roller is configured to rotate in a forward direction to convey a sheet to the tray and in a reverse direction to convey the sheet back toward the photosensitive drum. The first motor and the first transmission mechanism are disposed to the first frame. The first transmission mechanism is configured to transmit the drive force from the first motor to the fixing roller. The second motor and the second transmission mechanism are disposed to the second frame. The second transmission mechanism is includes a clutch mechanism configured to intermittently transmit the drive force from the second motor to the re-feeding roller.

A medium transportation apparatus includes a transportation portion for transporting a medium; a first structure unit for forming a first transportation path to guide and transport the medium in a first direction from an upstream side in a medium transportation direction toward a downstream side in the medium transportation direction; and a second structure unit for forming an accommodation space to accommodate a part of the first structure unit. The first structure unit includes a first region disposed outside the accommodation space on the downstream side in the medium transportation direction and a second region disposed inside the accommodation space on the upstream side in the medium transportation direction.

An image forming apparatus, having a photosensitive drum, an intermediate transfer belt located at a lower position with respect to the photosensitive drum to contact the photosensitive drum, a secondary transfer roller contacting the intermediate transfer belt, a first sheet tray located at a lower position with respect to the intermediate transfer belt to store a sheet, and a sheet guide to guide the sheet stored in the first sheet tray to a position between the intermediate transfer belt and the secondary transfer roller, is provided. The sheet guide is located between the intermediate transfer belt and the first sheet tray with regard to a vertical direction and has a curved section. A contact area between the secondary transfer roller and the intermediate transfer belt is located at a lower position with respect to an upper end portion of the curved section.

A sheet conveyer, comprising: a 1st conveying roller; a 1st support part to support the 1st conveying roller; a 1st helical gear to rotate together with the 1st conveying roller and to generate thrust in a particular direction; a 2nd conveying roller; a 2nd support part to support the 2nd conveying roller; a 2nd helical gear to generate thrust in the particular direction; a 3rd helical gear to engage with the 1st helical gear; a 4th helical gear to engage with the 2nd helical gear; and a clutch to connect or disconnect transmission of a driving force between the 3rd helical gear and the 4th helical gear, wherein: when the clutch is disconnected, the 1st and 2nd conveying rollers are disposed at an initial position, and when the clutch is connected, the 1st and 2nd conveying rollers move from the initial position in the particular direction.

An image forming apparatus includes an image forming unit, a fixing unit, a door for accessing the fixing unit and a member positioned on an upstream side of the fixing unit in a conveyance direction of the recording material, a conveyance path for a recording material having a length in the conveyance direction equal to or longer than a predetermined length, and a control unit. The image forming unit forms an image on a recording material. The fixing unit fixes the formed image on the recording material at a nip portion. The recording material with fixed image is conveyed on the conveyance path. In a case where a predetermined recording material is conveyed to the conveyance path when a length of the predetermined recording material in the conveyance direction is shorter than the predetermined length, the control unit stops conveyance of the nipped predetermined recording material at the nip portion.

A removable media handling module includes a body that is horizontally slidable into and removable from an imaging apparatus. The media handling module includes a lower media guide extending between a front and a rear of the body. With the media handling module inserted into the imaging apparatus, the lower media guide is positioned parallel to and spaced from a corresponding upper media guide mounted in the imaging apparatus to form at least a portion of a duplex media path therebetween. A drive mechanism including a clutched gear is operably connected to a feed roll assembly of the media handling module. The clutched gear is freely rotatable in a first direction that causes the feed roll assembly to rotate in a media process direction for feeding a printed media sheet along the duplex media path and is restrained from rotating in a second direction opposite the first direction.

A removable media handling module includes a body that is horizontally slidable into and removable from an imaging apparatus. The media handling module includes a lower media guide extending between a front and a rear of the body in a direction of insertion of the body into the imaging apparatus. With the media handling module inserted into the imaging apparatus, the lower media guide is positioned parallel to and spaced from a corresponding upper media guide mounted in the imaging apparatus to form at least a portion of a duplex media path therebetween. The media handling module includes a media feed through channel extending from a bottom of the body to an entrance of a simplex media path to allow media to be fed from a media tray below the media handling module and into the simplex media path when the media handling module is installed in the imaging apparatus.

An image forming apparatus includes: a reconveying unit including a reconveying roller; and a second transmission mechanism. The second transmission mechanism transmits a drive force to the reconveying roller and includes: an input gear; an output gear; an intermediate gear including first and second gears; and first and second swinging gears. The first toothless part of the first gear and the second toothless part of the second gear are provided at such a position that, when the intermediate gear is rotated by a drive force transmitted from the input gear through the second swinging gear while the second swinging gear meshes with the second toothed part of the second gear and the output gear meshes with the first toothed part of the first gear, the first toothless part reaches a position confronting the output gear and then the second toothless part reaches a position confronting the second swinging gear.

An image forming apparatus is configured such that in a case where images are to be formed on a first surface of a preceding sheet, on a first surface of a succeeding sheet fed to the first conveyance path succeeding to the preceding sheet and on a second surface of the preceding sheet, a first conveyance member is stopped without reversing the preceding sheet to a second conveyance path in a case where the image has been formed on the first surface of the preceding sheet and permission of preparing the image to be formed on the first surface of the succeeding sheet is not issued yet. The first conveyance member restarts conveyance of the preceding sheet to the second conveyance path based on timing when an image forming unit starts preparing the image to be formed on the first surface of the succeeding sheet.