A document sheet transportation device includes a feeding portion which feeds a document sheet from a document sheet placement portion toward a document sheet transportation path. The feeding portion includes a holder, a feeding member, a supporting body supported by the holder, a rotatable stopper member having a contact end portion allowed to contact a front end of a document sheet, and a biasing member which applies a biasing force to the stopper member. The stopper member is allowed to change a position among a first position in which the contact end portion contacts the front end of the document sheet, a second position which allows feeding of the document sheet by the feeding member, and a third position which is rotated in the first rotating direction from the second position. The biasing member applies the biasing force to the stopper member in a reverse second rotating direction.

An apparatus is disclosed. For example, the apparatus includes a paper feed to feed print media a single sheet at a time, a plurality of rotating discs, wherein each one of the plurality of rotating discs comprises an elastomer ring to secure a leading edge of the single sheet against a registration wall and initiate a flipping process, a plurality of fans to generate an air flow, wherein the air flow levitates a trailing edge of the single sheet during completion of the flipping process, and a movable platform to hold a stack of the print media.

A sheet flipping device includes a receiving member for receiving a sheet, a flipping volume being the volume which in operation is defined by the flipping movement of the sheet, and a flipping element for flipping the sheet around an axis of rotation within the flipping volume onto the receiving member. The sheet flipping device further includes an air vortex ring generator having an air vortex ring exit nozzle defining a translational direction of a generated air vortex ring when the generated vortex ring is in operation generated from the air vortex ring exit nozzle. The air vortex ring generator is mounted such that in operation the sheet is urged onto the receiving member by the air vortex ring during the flipping motion of the sheet through the flipping volume. A sheet stacking device and a printing apparatus include the sheet flipping device.

A sheet conveying apparatus includes a first rotator pair, a second rotator pair provided downstream, in a sheet conveying direction, of the first rotator pair, and a moving member having an abutment portion. the first rotator pair, the second rotator pair and the moving member are configured such that a rear end of the sheet does not pass on a moving trajectory of the abutment portion when the moving member moves from a passage state in which the sheet is allowed to pass through the abutment portion as the abutment portion is pressed by the sheet conveyed by the first rotator pair to an abutment state in which the abutment portion protrudes into a sheet conveying path.

A sheet conveying apparatus includes a first rotator pair, a second rotator pair provided downstream, in a sheet conveying direction, of the first rotator pair, and a moving member having an abutment portion. the first rotator pair, the second rotator pair and the moving member are configured such that a rear end of the sheet does not pass on a moving trajectory of the abutment portion when the moving member moves from a passage state in which the sheet is allowed to pass through the abutment portion as the abutment portion is pressed by the sheet conveyed by the first rotator pair to an abutment state in which the abutment portion protrudes into a sheet conveying path.

A sheet flipping device includes a receiving member for receiving a sheet, a flipping volume being the volume which in operation is defined by the flipping movement of the sheet, and a flipping element for flipping the sheet around an axis of rotation within the flipping volume onto the receiving member. The sheet flipping device further includes an air vortex ring generator having an air vortex ring exit nozzle defining a translational direction of a generated air vortex ring when the generated vortex ring is in operation generated from the air vortex ring exit nozzle. The air vortex ring generator is mounted such that in operation the sheet is urged onto the receiving member by the air vortex ring during the flipping motion of the sheet through the flipping volume. A sheet stacking device and a printing apparatus include the sheet flipping device.

A sheet post-processing device includes a conveying member, a processing tray, a processing section, a reference plate, an alignment member, a holder drive unit, and a control unit. The alignment member includes a paddle holder, and an alignment paddle having a paddle main body supported in a rotatable manner at the paddle holder, and a paddle part protruding from the paddle main body. The holder drive unit moves the alignment paddle in a reciprocating manner, between a reference position to separate the paddle part above a top sheet and an acting position to allow the paddle part to contact with the top sheet. The control unit sets a second acting position when the paddle part contacts with the sheet at n1-th time, to be higher than a first acting position when the paddle part contacts with the sheet at m1-th time, where 1m1<n1 holds.