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.

A sheet conveyance apparatus includes a conveyance roller, an abutment member including an abutment surface, an obliquely conveying roller configured to convey the sheet such that the side edge portion is moved toward the abutment surface, a sheet side-edge detection portion, and a controller. The controller is configured to control the conveyance force of the obliquely conveying roller at a first conveyance force until a predetermined time has elapsed, in an abutment operation in which the sheet is abutted against the abutment surface by the obliquely conveying roller, and control the conveyance force of the obliquely conveying roller at a second conveyance force larger than the first conveyance force if the predetermined time has elapsed and the position of the side edge portion of the sheet detected by the sheet side-edge detection portion is out of a predetermined range.

A sheet transport system for moving a sheet in a transport direction while adjusting a position of the sheet in a lateral direction normal to the transport direction to a target position, includes first and second pinch roller sets spaced apart from one another in the transport direction, each pinch roller set including two pairs of pinch rollers spaced apart from one another in the lateral direction, each pair forming a nip for pinching and driving the sheet with an individually controllable speed; a detection system for detecting a position of the sheet in the lateral direction while the sheet is pinched by the first pinch roller set; and a control system configured for carrying out the following actions: by controlling the speeds of the pinch rollers of the first pinch roller set before the sheet has reached the second pinch roller set, rotating the sheet by a first rotation angle for adjusting a given reference point on a leading part of the sheet to its target position; and when the sheet has left the first pinch roller set and while the reference point travels along a path segment that is symmetric with respect to the second pinch roller set, rotating, by controlling the speeds of the pinch rollers of the second pinch roller set, the sheet by a second rotation angle for aligning a leading edge of the sheet in the lateral direction.

A sheet transport system for moving a sheet in a transport direction while adjusting a position of the sheet in a lateral direction normal to the transport direction to a target position, includes first and second pinch roller sets spaced apart from one another in the transport direction, each pinch roller set including two pairs of pinch rollers spaced apart from one another in the lateral direction, each pair forming a nip for pinching and driving the sheet with an individually controllable speed; a detection system for detecting a position of the sheet in the lateral direction while the sheet is pinched by the first pinch roller set; and a control system configured for carrying out the following actions: by controlling the speeds of the pinch rollers of the first pinch roller set before the sheet has reached the second pinch roller set, rotating the sheet by a first rotation angle for adjusting a given reference point on a leading part of the sheet to its target position; and when the sheet has left the first pinch roller set and while the reference point travels along a path segment that is symmetric with respect to the second pinch roller set, rotating, by controlling the speeds of the pinch rollers of the second pinch roller set, the sheet by a second rotation angle for aligning a leading edge of the sheet in the lateral direction.

A detection device includes a first detection unit that detects a leading edge portion and a trailing edge portion of a medium while the medium is being transported, and a second detection unit that detects both edge portions of the medium in an orthogonal direction that is orthogonal to a transporting direction of the medium while the medium is being transported.

A detection device includes a first detection unit that detects a leading edge portion and a trailing edge portion of a medium while the medium is being transported, and a second detection unit that detects both edge portions of the medium in an orthogonal direction that is orthogonal to a transporting direction of the medium while the medium is being transported.

An image forming apparatus configured to form images on both sides of a sheet, includes an image forming unit, which is configured to form an image on an image bearing member, and a sheet conveying device, which is configured to move the sheet being conveyed toward a width direction, which is orthogonal to a conveyance direction. After the formed image is transferred onto a first surface of the sheet, the image forming apparatus inverts and conveys the sheet to transfer an image onto a second surface. Moreover, a side edge position of the sheet in the width direction is detected during conveyance for the transferring onto each of the first surface and the second surface, and an image writing start position for the image forming unit is determined based on a result of the detection to store a result of the determination in a memory.

An image forming apparatus includes an image forming unit, a reversing roller pair, a moving unit, and an obtaining unit. The image forming unit forms an image on a sheet. The reversing roller pair nips the sheet having the image, rotates in a first direction, and then rotate in a second direction and conveys the sheet. The moving unit moves the reversing roller pair. The obtaining unit obtains the sheet length. If a first sheet having a first length is reversed and conveyed, the moving unit moves the reversing roller pair conveying the first sheet in the width direction by a first moving amount. If a second sheet having a second length greater than the first length is reversed and conveyed, the moving unit moves the reversing roller pair conveying the second sheet in the width direction by a second moving amount smaller than the first moving amount.