A sheet post-processing device is connected to a punch processing unit. The punch processing unit includes a skew detection unit and a punch unit. The skew detection unit detects a skew amount of a sheet. The punch unit forms punch holes at positions of the sheet according to the skew amount. The sheet post-processing device includes a processing tray, a paddle, a driver, and a control unit. The sheet of which the skew amount is detected by the skew detection unit is mounted on the processing tray. The paddle conveys the sheet on the processing tray by a paddle operation. The driver drives the paddle to perform the paddle operation. The control unit is configured to operate the driver to control a number of times the paddle operation is performed by the paddle based on the skew amount.

A sheet conveyance method using a sheet conveyance apparatus that includes a conveyance path and a plurality of alignment members disposed along the conveyance path, the method includes: determining a set of alignment members to be operated based on a length of the paper sheet from among the plurality of alignment members; and aligning the paper sheet conveyed on the conveyance path using the determined set of alignment members.

An image forming apparatus includes a controller to move a sheet, in an image formation process on a first surface, to a standard position in a width direction and move the sheet, in an image formation process on a second surface, in the width direction based on a detected position in a case where a difference between the standard position and a first position in the width direction is equal to or smaller than a predetermined value. The controller moves the sheet, in the image formation process on the first surface, by the predetermined value in the width direction and moves the sheet, in the image formation process on the second surface, in the width direction based on detected positions in a case where the difference between the standard position and the first position in the width direction is larger than the predetermined value.

An image forming apparatus includes a controller to move a sheet, in an image formation process on a first surface, to a standard position in a width direction and move the sheet, in an image formation process on a second surface, in the width direction based on a detected position in a case where a difference between the standard position and a first position in the width direction is equal to or smaller than a predetermined value. The controller moves the sheet, in the image formation process on the first surface, by the predetermined value in the width direction and moves the sheet, in the image formation process on the second surface, in the width direction based on detected positions in a case where the difference between the standard position and the first position in the width direction is larger than the predetermined value.

An image forming apparatus includes a controller to move a sheet, in an image formation process on a first surface, to a standard position in a width direction and move the sheet, in an image formation process on a second surface, in the width direction based on a detected position in a case where a difference between the standard position and a first position in the width direction is equal to or smaller than a predetermined value. The controller moves the sheet, in the image formation process on the first surface, by the predetermined value in the width direction and moves the sheet, in the image formation process on the second surface, in the width direction based on detected positions in a case where the difference between the standard position and the first position in the width direction is larger than the predetermined value.

A second roller set is disposed separately from a first roller set in one direction of the conveyance direction, and includes an intermittent roller that generates, during one rotation, a conveyance enabled time of contacting the card and conveying the card and a conveyance disabled time of not contacting the card and not conveying the card. A third roller set is disposed separately from the second roller set. A reference guide wall receives abutments of a first end portion of the card and arranges a position of the card in the width direction at a reference position. An urging guide wall urges a second end portion of the card toward the reference guide wall by a first urging force. A support wall regulates a movement of the reference guide wall toward the urging guide wall at a position serving as the reference position.

A post-processing apparatus performs post-processing on a paper sheet conveyed from a previous stage side, and includes: a corrector that performs bend correction on the paper sheet, in accordance with one of a plurality of bend correction methods; a post-processor that performs the post-processing on the paper sheet subjected to the bend correction performed by the corrector; and a hardware processor that selects one of the plurality of bend correction methods, on the basis of a bend correction accuracy corresponding to a product to be created by the post-processing being performed by the post-processor, and a productivity of the product, wherein from the plurality of bend correction methods, the hardware processor selects a bend correction method that reduces a difference between a post-processing time required for the post-processor to perform the post-processing and a correction time required for the corrector to perform the bend correction on the paper sheet.

A feeder of a sheet treating or a sheet processing machine comprises a sensor system, which sensor system, on a front side pointing in a direction of transport of the sheets to be fed or on the opposing, rear side of the pile of sheets to be fed, comprises one or more sensors, by the use of which sensors, a distance, with respect to at least two locations, which are spaced apart from one another transversely to the transport direction, at the relevant front or rear sides of the pile, can be ascertained. A method is provided for detecting or correcting sheets having deviated positions or dimensions in such a sheet feeder of a sheet treating or processing machine.

A sheet conveying device includes a sheet detection unit and a position adjusting mechanism. The position adjusting mechanism is disposed on a downstream side of the sheet detection unit in a sheet conveying direction in the sheet conveying path, includes an adjusting roller pair, and performs skew correction and positional displacement correction of a sheet, while conveying the sheet. The sheet conveying path includes a first conveying roller pair disposed on an upstream side of the position adjusting mechanism in the sheet conveying direction, and a curved part disposed between the adjusting roller pair and the first conveying roller pair, which curves in an S shape so as to be convex in a front and back side direction of the sheet alternately at different positions in the sheet conveying direction. The adjusting roller pair nips and conveys the sheet together with the first conveying roller pair.

A sheet processing system according to an embodiment includes a tray that supports a sheet on opposite sides of the sheet orthogonal to a conveyance direction of the sheet. The tray includes a first adjustable support and second adjustable support positioned opposite the first adjustable support in the direction orthogonal to the conveyance direction of the sheet. A skew sensor detects a skew angle of the sheet conveyed to the tray. A corner sensor detects positions of each corner on a front end in the downstream direction of the sheet conveyed to the tray. A controller controls movement of the first and second adjustable supports based on the detected skew angle and the detected positions of each corner on the front end of the sheet conveyed to the tray so that the sheet is conveyed to the tray without jamming.