An image forming apparatus includes an image carrier, an endless intermediate transfer belt, a primary transfer member, a secondary transfer member, a displacement amount detecting device, and a control unit. The displacement amount detecting device detects displacement amounts of a reference image in a main-scanning direction and a sub-scanning direction. The reference image is formed on the intermediate transfer belt. The displacement amount detecting device includes a density detecting sensor and a surface potential sensor. The density detecting sensor detects a print density of the reference image formed on the intermediate transfer belt. The surface potential sensor detects a surface potential of the reference image. The displacement amount detecting device simultaneously detects the identical reference image using the density detecting sensor and the surface potential sensor to ensure simultaneous detections of displacement amounts in the main-scanning direction and the sub-scanning direction.

The purpose of the present invention is to provide a post-processing apparatus capable of performing conveying to and storing at a predetermined stack tray without causing sheet jamming even when a sheet having larger size than a standard size is introduced. The present invention comprises a post-processing apparatus as a processing tray on which sheets conveyed in a predetermined conveyance direction are stacked into a bundle shape, an aligning device which aligns the sheets conveyed to the processing tray, a binding device which performs a binding process on the sheets aligned by the aligning device, and a controller which controls the aligning device so that a sheet is aligned at a position being apart from the binding device by a predetermined distance when the sheet conveyed to the processing tray has a predetermined size or larger.

An image forming apparatus includes an image carrier, an endless intermediate transfer belt, a primary transfer member, a secondary transfer member, a displacement amount detecting device, and a control unit. The displacement amount detecting device detects displacement amounts of a reference image in a main-scanning direction and a sub-scanning direction. The reference image is formed on the intermediate transfer belt. The displacement amount detecting device includes a density detecting sensor and a surface potential sensor. The density detecting sensor detects a print density of the reference image formed on the intermediate transfer belt. The surface potential sensor detects a surface potential of the reference image. The displacement amount detecting device simultaneously detects the identical reference image using the density detecting sensor and the surface potential sensor to ensure simultaneous detections of displacement amounts in the main-scanning direction and the sub-scanning direction.

A method for reducing skew in a media advance system comprises advancing a media from a media roll (6a) through a feed roller (3) towards the nip of a drive roller (4); reducing a media transportation speed at the feed roller (3) relative to the media transportation speed at the drive roller (4) for a predetermined period of time when a leading edge of the media reaches the nip of the drive roller; and cutting the media to a predetermined page size at a position upstream of the feed roller.

An information processing device performs processing of specifying a positional relationship between a first printing section and a second printing section based on image capturing data of a test image that is printed on a printing medium by the first printing section and the second printing section in each of which a plurality of printing elements are arranged. The test image includes a plurality of first lines which are printed by the first printing section so as to have printing positions different from each other in a line arrangement direction on the printing medium and a plurality of second lines which are printed by the second printing section so as to have printing positions different from each other in the line arrangement direction. The information processing device contains a printing coordinate acquisition section, a printing position acquisition section, and a positional shift amount calculation section.

An image forming apparatus includes a pair of registration rollers, an image formation unit, a roller movement mechanism, a detection unit and a control unit which performs a displacement correction for moving the pair of registration rollers from a home position. The control unit determines tendency information indicating the tendency of a displacement direction and a displacement amount of a sheet, the control unit displaces the home position in a direction opposite to the displacement direction indicated by the tendency information only by the displacement amount indicated by the tendency information and the control unit displaces the writing start position of an electrostatic latent image in a main scanning direction in the displacement direction indicated by the tendency information only by the displacement amount indicated by the tendency information.

An image forming system includes: a sheet conveying section configured to convey a long sheet; an image forming/fixing section configured to execute an image forming/fixing operation to form and fix a toner image on the long sheet to be conveyed by the sheet conveying section; a skew detection section configured to detect a skew of the long sheet to be conveyed by the sheet conveying section; a skew correction section configured to execute a skew correction operation to correct the skew of the long sheet; and a control section configured to perform control to execute the skew correction operation when the skew has been detected in a first area where the skew correction operation does not affect the image forming/fixing operation, and perform control to execute the skew correction operation when the skew has been detected in a second area where the skew correction operation affects the image forming/fixing operation.

An image-forming apparatus that is capable of accurately detecting skew angle when arriving at a resist roller. In the image-forming apparatus, the resist roller feeds the printing paper to a printing unit at specified timing, and the printing unit performs printing on the printing paper. The flat-conveying section is formed between the paper-supply roller and the resist roller, and conveys the paper in a flat state. The camera takes images of the edge of the front end of the printing paper that is conveyed in the flat-conveying section. The camera-driving apparatus causes the camera to move along the flat-conveying section at the designed conveying speed of the printing paper. The skew-detection unit, based on images taken in the flat-conveying section by the camera, detects the skew angle when arriving at the resist roller as the arrival skew angle.

An image forming apparatus includes: a plurality of droplets ejecting members that are opposed to a continuous sheet being conveyed, are arranged in a sheet conveying direction, and eject droplets onto the continuous sheet; movement restriction members that restrict movement, in a sheet width direction, of one end portion, in the sheet width direction, of a portion, opposed to the droplets ejecting members, of the continuous sheet; and tension application members that give tension in the sheet width direction to the portion, opposed to the droplets ejecting members, of the continuous sheet in a state that movement, in the sheet width direction, of the portion, opposed to the droplets ejecting members, of the continuous sheet is restricted by the movement restriction members.

An aligning unit stores a paper bundle that is formed by inserting a medium that is different from printed body text paper sheets conveyed from a printer into the printed body text paper sheets. A manual paper feeding unit stores a medium that is manually fed. A conveyance control unit makes the medium be conveyed from the manual paper feeding unit to the aligning unit after the body text paper sheets that include a page specified by a print job are stored in the aligning unit and before the body text paper sheet conveyed from the printer immediately afterwards is stored in the aligning unit.