A conveyance device includes a conveyance roller, a registration roller, a sensor, a mode setting part, a storage, a conveyance state determination part and a drive control part. The mode setting part sets the mode to either a plain paper mode or a tab paper mode. The storage stores threshold information corresponding to the mode. The conveyance state determination part determines, when the plain paper mode is set, whether the conveyance state of the recording medium is a skew conveyance state or a tab paper conveyance state, based on the detection result of the sensor and the plain paper mode threshold information. The conveyance state determination part determines, when the tab paper mode is set, whether the conveyance state of the recording medium is the skew conveyance state or the tab paper conveyance state, based on the detection result of the sensor and the tab paper mode threshold information.

A sheet conveyance device includes a conveyance roller pair. A skew correction roller pair conveys the sheet after contacting two nip portions, and a sheet skew is corrected in a state in which the skew correction roller pair is being stopped. The sheet having a toner image is bent by a first conveyance guide such that a sheet first surface becomes an inside surface. The sheet is bent by the first and second conveyance guides to cause the sheet first surface to be the inside surface and a sheet second surface to be an outside surface. The skew correction roller pair includes two first rotary members of a first roller. A second roller and the two first rotary members form the two nip portions. The second roller and the first conveyance guide contact the sheet first surface. The first roller and the second conveyance guide contact the sheet second surface.

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.

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 sheet conveyance device includes a registration roller pair including a first roller and a second roller, configured to form a nip by the first roller and the second roller, and configured to correct a skew of a sheet conveyed thereto by allowing the sheet to abut the nip. The first roller includes an outer peripheral surface with a groove portion, the groove portion being formed in a region in which a corner portion of a sheet abuts the outer peripheral surface, and causing a part of the outer peripheral surface to be concave and another part of the outer peripheral surface to be convex in an axial direction.

A sheet aligning mechanism includes first and second conveyance mechanisms disposed on first and second sides of a sheet conveyance path, respectively. A nip is formed between the first and second conveyance mechanisms. The first conveyance mechanism includes a first roller, a second roller, and a first conveyance belt wound around the first and second rollers. The first and second rollers are configured to rotate in a first direction along a sheet conveying direction for sheet conveyance, and stop rotation or rotate in a second direction opposite to the first direction for sheet alignment. The first conveyance belt includes an extended region between the first and second rollers in an extending direction inclined with respect to the sheet conveying direction, such that a width of the sheet conveyance path becomes narrower towards the nip in the sheet conveying direction.

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.

An image forming apparatus including an image forming unit, a discharging portion, a supporting portion, an image reading portion, and a switching portion is provided. The image forming unit is configured to form an image on a sheet. The discharging portion is configured to discharge the sheet on which the image has been formed. The supporting portion is configured to support the sheet discharged by the discharging portion. The image reading portion is configured to read, at a reading position, the image formed on the sheet. The switching portion is configured to switch between causing the sheet discharged by the discharging portion to be conveyed to the supporting portion and causing the sheet discharged by the discharging portion to be conveyed toward the image reading portion. The sheet conveyed toward the image reading portion is conveyed to the reading position after conveyance by the discharging portion is finished.

A printing apparatus includes a feeding unit, a pair of rollers, a printing unit, and a control unit. The control unit can execute skew correction. The control unit can execute control to convey a preceding printing medium and a succeeding printing medium by the pair of rollers in a state in which a trailing edge portion of the preceding printing medium and a leading edge portion of the succeeding printing medium overlap. The control unit sets an execution timing of the skew correction for the succeeding printing medium based on positions of the preceding printing medium and the succeeding printing medium if a predetermined condition is met. The predetermined condition is that the preceding printing medium reaches a position at which a remaining print range for the preceding printing medium equals a predetermined print range.

A paper conveying apparatus and an image forming apparatus are described which can appropriately convey a sheet when the sheet is restarted after forming a loop. The paper conveying apparatus includes a conveying roller pair in the upstream side of a loop roller pair, a stepping motor for rotationally driving the conveying roller pair, and a processor for controlling rotation of the stepping motor by controlling pulse signals and excitation current supplied to the stepping motor. This processor halts rotation of the conveying roller pair by stopping output of the pulse signals when loop formation of the sheet is completed, and switches the excitation current to a lower current value which is lower than a reference current value at which excitation is turned on.