A sheet transfer device for transferring a sheet between two sheet processing devices comprising a switch for directing sheets from a first transport path coming from the first sheet processing device onto a two-way transport path or for directing sheets from the two-way transport path onto a second transport path for feeding sheets to the second sheet processing device. A transport pinch is provided along the two way transport path for reversing a sheet on the two-way transport path. When in use, the two-way transport path extends downward in a vertically extending free-hanging chamber wherein the sheet engaged by the transport pinch is allowed to hang freely under the influence of gravity. Thereby, a compact device is formed which is able to adjust the sheet to a suitable orientation for the second processing device. The device further prevents forces from the first processing device to disrupt the sheet's orientation in the second processing device.

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 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.

A medium conveyance apparatus includes a first sensor located at a center part in a direction perpendicular to a medium conveyance direction; a second sensor located at a downstream side from the first sensor in the medium conveyance direction and at the center part in the direction perpendicular to the medium conveyance direction, a third sensor located at a downstream side from the second sensor in the medium conveyance direction and at the one side in the direction perpendicular to the medium conveyance direction, and a processor to determine whether a tilt angle of the medium being conveyed has changed based on a time from when the first sensor detects the medium to when the second sensor detects the medium when the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third.

A medium conveyance apparatus includes a first sensor located at a center part in a direction perpendicular to a medium conveyance direction; a second sensor located at a downstream side from the first sensor in the medium conveyance direction and at the center part in the direction perpendicular to the medium conveyance direction, a third sensor located at a downstream side from the second sensor in the medium conveyance direction and at the one side in the direction perpendicular to the medium conveyance direction, and a processor to determine whether a tilt angle of the medium being conveyed has changed based on a time from when the first sensor detects the medium to when the second sensor detects the medium when the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third.

A sheet feeding device includes a feeding roller pair, a detecting portion, a first changing portion, a second changing portion, and a controller for controlling the first changing portion and the second changing portion. The controller starts a first feeding operation for feeding a sheet toward the obliquely feeding roller pair in a nipping state of the feeding roller pair and then starts a second feeding operation for feeding the sheet for abutting a side end of the sheet against the reference member in the nipping state of the obliquely feeding roller pair. The controller changes, after the first feeding operation is started and before the second feeding operation is started, a start timing of the second feeding operation on the basis of a detection result of a position of the side end of the sheet detected by the detecting portion.

A sheet feeding device includes a feeding roller pair, a detecting portion, a first changing portion, a second changing portion, and a controller for controlling the first changing portion and the second changing portion. The controller starts a first feeding operation for feeding a sheet toward the obliquely feeding roller pair in a nipping state of the feeding roller pair and then starts a second feeding operation for feeding the sheet for abutting a side end of the sheet against the reference member in the nipping state of the obliquely feeding roller pair. The controller changes, after the first feeding operation is started and before the second feeding operation is started, a start timing of the second feeding operation on the basis of a detection result of a position of the side end of the sheet detected by the detecting portion.

A sheet processing machine, in particular a sheet-fed printing press or a sheet die cutting machine, has a sheet infeed having at least one stop for feeding and aligning sheets, and has a device for monitoring sheet travel along a sheet transport path of the sheet infeed. At least one measurement system, for detecting a lateral sheet edge of the sheet, is provided. A method is also provided for monitoring sheet travel along a sheet transport path in a sheet infeed. An alternative device and an alternative method for monitoring sheet travel along a transport path of a sheet processing machine are provided. At least one sensor, which can be associated with the lateral region of the sheet transport path, and which is configured for the optical detection and determination of the position of a mark on the sheet, is utilized.

An image forming apparatus includes a control portion configured to control, based on a detection position of a sheet in a width direction, in a case where a center of an image formed on a first surface at an image forming portion in the width direction is displaced from a center of the sheet in the width direction at the image forming position and an image is to be formed on a second surface of the sheet, a moving portion to move the sheet in the width direction such that a position of the center of the sheet on a conveyance path in the width direction at the sheet forming position when the image is formed on the first surface and a position of a center of the sheet on the conveyance path in the width direction at the sheet forming position when the image is formed on the second surface coincide.

An image forming apparatus includes a control portion configured to control, based on a detection position of a sheet in a width direction, in a case where a center of an image formed on a first surface at an image forming portion in the width direction is displaced from a center of the sheet in the width direction at the image forming position and an image is to be formed on a second surface of the sheet, a moving portion to move the sheet in the width direction such that a position of the center of the sheet on a conveyance path in the width direction at the sheet forming position when the image is formed on the first surface and a position of a center of the sheet on the conveyance path in the width direction at the sheet forming position when the image is formed on the second surface coincide.