A print medium feeding device comprises a pickup roller, a forward roller, a registration roller, a sensing unit, and a processor. The processor adjusts a first driving signal and a second driving signal based on a difference between a first time and a second time and controls driving of the registration roller using adjusted signals, the first driving signal adjusting a waiting position of the print medium in the registration roller, the second driving signal feeding the print medium waiting at the adjusted waiting position to the image forming unit, the first time associated with transport of the print medium from the pickup roller to the sensing unit, and the second time being measured by sensing the print medium transported from the pickup roller to the sensing unit.

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 controller starts sheet feeding at a primary sheet feeding speed, then momentarily stops a sheet feeding rotary member, and thereafter starts secondary sheet feeding. When the secondary sheet feeding speed equals a first speed, the controller momentarily stops the sheet feeding rotary member such that the leading end of a document sheet stops at a first stop position. When the secondary sheet feeding speed equals a second speed, the controller momentarily stops the sheet feeding rotary member such that the leading end of a document sheet stops at a second stop position. The second stop position is located downstream of the first stop position in the document conveying direction.

In an image forming apparatus that can form images on both surfaces of a sheet, a first roller conveys a sheet conveyed from a reversal roller and a first motor drives the reversal and first rollers. A one-way clutch restricts transfer of a driving force from the first motor to the first roller while the reversal roller is conveying a sheet in a first direction, and permits transfer of a driving force from the first motor to the first roller while the reversal roller is conveying a sheet in a second direction. Second and third rollers are provided on a downstream side of the first roller. A second motor drives the second and third rollers. A controller drives both of the first and second motors when resuming conveyance of a sheet conveyed on a duplex conveyance path after causing the sheet to await abutment with the second roller.

A sheet conveyance device, an image forming apparatus, and a sheet conveying method that convey a sheet in a predetermined sheet conveyance direction make a surface moving speed of a driven roller higher than a surface moving speed of a drive roller when a rotational driving force from the drive roller is transmitted to the driven roller, and by a one-way clutch that is provided at any place in a drive transmission path from the drive roller to the driven roller, restrict relative rotation of the driven roller in a first rotation direction, which is the sheet conveyance direction, with respect to the drive roller while allowing relative rotation of the driven roller in a second rotation direction, which is a direction opposite to the first rotation direction, with respect to the drive roller.

Disclosed herein is a sheet-folding apparatus which includes transporting rollers, folding rollers, a pushing member provided between the transporting rollers and the folding-rollers, and a guide unit for guiding the sheet to the folding-roller pair by using the pushing member.

A sheet processing apparatus includes a roller pair configured to convey a sheet, a sheet bundle conveyer configured to convey a sheet bundle to the roller pair, and circuitry configured to cause the sheet bundle conveyer to contact leading edges of sheets of the sheet bundle to the roller pair and cause the roller pair to rotate in reverse to align the leading edges of the sheets of the sheet bundle.

A printing apparatus includes a feeding roller configured to feed a printing sheet stacked on a stacking unit, a conveyance roller configured to convey the printing sheet fed by the feeding roller, a printing unit configured to print the printing sheet conveyed by the conveyance roller, a conveyance control unit configured to control conveyance of printing sheets so that the trailing edge of a preceding sheet as a printing sheet precedingly fed from the stacking unit and the leading edge of a succeeding sheet as a printing sheet succeedingly fed from the stacking unit overlap each other, and a determination unit configured to determine whether to convey the succeeding sheet to a position facing the printing unit while keeping an overlap state between the preceding sheet and the succeeding sheet.

An image forming apparatus is provided. The image forming apparatus includes a paper-feed unit, a developing unit to form an image in a printing medium, an insertion unit including first and second rollers configured to insert the printing medium conveyed from the paper-feed unit into the developing unit, and a guide unit rotatably disposed about a rotation shaft of the first roller and configured to guide the printing medium moving from the paper-feed unit to the insertion unit and selectively press the first roller to the second roller.

Provided is a sheet folding apparatus for folding sheets, including: a feeding-roller pair; a loop-forming space provided downstream from the feeding-roller pair, for forming a sheet loop; a pushing member for pushing the looped sheet; a folding-roller pair for nipping a prescribed part of the sheet pushed by the pushing member, thereby to fold the sheet; and a path provided between the feeding-roller pair and the folding-roller pair, for guiding the sheet fed from the feeding-roller pair toward the loop-forming space.