When duplex printing non-rectangular sheets of printable media, the sheets require proper registration to prevent misalignment of front and back images. This is ensured by: determining relative orientations of three different edges of a sheet being transported towards print station on a first pass; registering the sheet on the first pass by aligning one of the edges with respect to a predetermined alignment direction; printing a first image on a first side of the registered sheet; flipping the sheet on a second pass; registering the flipped sheet by aligning one of the edges with respect to a predetermined alignment direction; and printing a second image on a second side of the registered, flipped sheet aligned with the first image based on the determined relative orientations.

A sheet folding apparatus for folding sheets comprising a curved conveyance path along which the sheets are moved successively in first and second opposite directions, the curved conveyance path being such that the sheets cannot naturally register to reach a folding position by simple effect of gravity, wherein to register the sheets before to fold them transport rollers having loaded the sheets in the first direction moves back in the second opposite direction for compressing the sheets against an adjustable low stop member to generate an elastic deformation of the sheets sufficient to compensate friction in the curved conveyance path and automatically register the sheets.

A sheet folding apparatus for folding sheets comprising a curved conveyance path along which the sheets are moved successively in first and second opposite directions, the curved conveyance path being such that the sheets cannot naturally register to reach a folding position by simple effect of gravity, wherein to register the sheets before to fold them transport rollers having loaded the sheets in the first direction moves back in the second opposite direction for compressing the sheets against an adjustable low stop member to generate an elastic deformation of the sheets sufficient to compensate friction in the curved conveyance path and automatically register the sheets.

An image forming apparatus has an apparatus main body, a sheet conveyance passage, a cover member, a conveyance unit, a sheet tray, a first sheet feeding portion, and a feed unit. The sheet conveyance passage is inside the apparatus main body. The conveyance unit is inside the cover member and is supported to be pivotable between an open position and a closed position. The first sheet feeding portion has a feed unit. The conveyance unit has a swing guide of which a lower end part is swingably supported on the apparatus main body and which, in the closed position, is located in a first position to face the feed unit and constitute part of the sheet conveyance passage and, in the open position, is located in a second position to be located away from the feed unit.

A drive transferring unit includes a first roller, a second roller, a first clutch, a second clutch, a transferring section, and a control section. The first roller includes a first shaft section. The second roller includes a second shaft section. The first clutch switches between enabling transfer of a driving force to the first shaft section and interrupting transfer thereof. The second clutch switches between enabling transfer of the driving force to the second shaft section and interrupting transfer thereof. The transferring section transfers the driving force from one of the first roller and the second roller to the other. The control section selects between first control in which the first clutch is in the on state and the second clutch is in the off state and second control in which the second clutch is in the on state and the first clutch is in the off state.

A sheet processing apparatus includes a conveyance unit that conveys a sheet, a processing unit that performs processing on the sheet conveyed by the conveyance unit, and a controller that controls the conveyance unit and the processing unit. The processing unit includes a cutting unit capable of cutting the sheet along a cutting line, a holding unit that is configured to be movable between a holding position and a release position and that is disposed such that a holding line, which is formed on the sheet when the sheet is held, is substantially parallel to the cutting line, and an angle adjuster capable of adjusting an angle of the cutting unit and the holding unit with respect to a conveying direction.

An image forming apparatus has an apparatus main body, a sheet conveyance passage, a cover member, a conveyance unit, a sheet tray, a first sheet feeding portion, and a feed unit. The sheet conveyance passage is inside the apparatus main body. The conveyance unit is inside the cover member and is supported to be pivotable between an open position and a closed position. The first sheet feeding portion has a feed unit. The conveyance unit has a swing guide of which a lower end part is swingably supported on the apparatus main body and which, in the closed position, is located in a first position to face the feed unit and constitute part of the sheet conveyance passage and, in the open position, is located in a second position to be located away from the feed unit.

A drive transferring unit includes a first roller, a second roller, a first clutch, a second clutch, a transferring section, and a control section. The first roller includes a first shaft section. The second roller includes a second shaft section. The first clutch switches between enabling transfer of a driving force to the first shaft section and interrupting transfer thereof. The second clutch switches between enabling transfer of the driving force to the second shaft section and interrupting transfer thereof. The transferring section transfers the driving force from one of the first roller and the second roller to the other. The control section selects between first control in which the first clutch is in the on state and the second clutch is in the off state and second control in which the second clutch is in the on state and the first clutch is in the off state.

This sheet feeding device includes a paper transport path, a first paper pass detection unit, a second paper pass detection unit, a transport processing mechanism, an actuation determining section, and a detection control section. The first paper pass detection unit detects that the paper passes through a first point on the paper transport path. The second paper pass detection unit detects that the paper passes through a second point on the paper transport path. The transport processing mechanism performs predetermined transportation processing on the paper traveling on the paper transport path. The actuation determining section determines whether the transport processing mechanism has been actuated. The detection control section controls the first paper pass detection unit to constantly perform detection, and, if the actuation determining section detects that transport processing mechanism has been actuated, controls the second paper pass detection unit to perform detection except for a certain time period.

A sheet processing apparatus includes a conveyance unit that conveys a sheet, a processing unit that performs processing on the sheet conveyed by the conveyance unit, and a controller that controls the conveyance unit and the processing unit. The processing unit includes a cutting unit capable of cutting the sheet along a cutting line, a holding unit that is configured to be movable between a holding position and a release position and that is disposed such that a holding line, which is formed on the sheet when the sheet is held, is substantially parallel to the cutting line, and an angle adjuster capable of adjusting an angle of the cutting unit and the holding unit with respect to a conveying direction.