A sheet conveyance device includes: a first conveyance path configured to allow a sheet to be conveyed along the first conveyance path; a second conveyance path that extends upward from a branch position in the first conveyance path; a third conveyance path that extends downward from the branch position; a first conveyance roller disposed in the second conveyance path and configured to rotate normally and reversely to convey the sheet; a first drive motor disposed below the branch position; and a first belt disposed in a drive transmission path from the first drive motor to the first conveyance roller and configured to transmit a driving force from the first drive motor to the first conveyance roller.

An image reading device includes a first power transmission section configured to transmit a driving force to the input gear, wherein the first power transmission section is configured to transmit the driving force from a first drive source that drives the feed roller to the input gear and furthermore, the first power transmission section includes a one-way clutch that does not transmit the power of the first drive source to the input gear when the first drive source rotates in a first rotation direction, which is a rotation direction during medium feeding, and transmits the power of the first drive source to the input gear when the first drive source rotates in a second rotation direction, which is opposite to the first rotation direction.

An image forming apparatus includes a reconveying unit including a reconveying roller; and a second transmission mechanism. The second transmission mechanism transmits a drive force to the reconveying roller and includes an input gear; an output gear; an intermediate gear including first and second gears; and first and second swinging gears. The first toothless part of the first gear and the second toothless part of the second gear are provided at such a position that, when the intermediate gear is rotated by a drive force transmitted from the input gear through the second swinging gear while the second swinging gear meshes with the second toothed part of the second gear and the output gear meshes with the first toothed part of the first gear, the first toothless part reaches a position confronting the output gear and then the second toothless part reaches a position confronting the second swinging gear.

An image forming apparatus includes a reconveying unit including a reconveying roller; and a second transmission mechanism. The second transmission mechanism transmits a drive force to the reconveying roller and includes an input gear; an output gear; an intermediate gear including first and second gears; and first and second swinging gears. The first toothless part of the first gear and the second toothless part of the second gear are provided at such a position that, when the intermediate gear is rotated by a drive force transmitted from the input gear through the second swinging gear while the second swinging gear meshes with the second toothed part of the second gear and the output gear meshes with the first toothed part of the first gear, the first toothless part reaches a position confronting the output gear and then the second toothless part reaches a position confronting the second swinging gear.

A sheet conveying device includes: a sheet discharge roller disposed in a conveying path of sheets so as to discharge a sheet being conveyed to a sheet discharge tray; a conveying unit that conveys sheets on a side of the conveying path closer to an upstream side than the sheet discharge roller; a motor that rotates at a constant system speed during conveying of sheets to drive the conveying unit; a transmission mechanism that transmits power of the motor to the sheet discharge roller to rotate the sheet discharge roller; and a controller that controls an operation of the transmission mechanism, wherein the transmission mechanism changes a circumferential speed of the sheet discharge roller, and the controller performs speed reduction control of controlling the operation of the transmission mechanism to temporarily reduce the circumferential speed of the sheet discharge roller when a sheet is discharged to the sheet discharge tray.

An image forming apparatus includes: a reconveying unit including a reconveying roller; and a second transmission mechanism. The second transmission mechanism transmits a drive force to the reconveying roller and includes: an input gear; an output gear; an intermediate gear including first and second gears; and first and second swinging gears. The first toothless part of the first gear and the second toothless part of the second gear are provided at such a position that, when the intermediate gear is rotated by a drive force transmitted from the input gear through the second swinging gear while the second swinging gear meshes with the second toothed part of the second gear and the output gear meshes with the first toothed part of the first gear, the first toothless part reaches a position confronting the output gear and then the second toothless part reaches a position confronting the second swinging gear.

A sheet conveying device includes: a sheet discharge roller disposed in a conveying path of sheets so as to discharge a sheet being conveyed to a sheet discharge tray; a conveying unit that conveys sheets on a side of the conveying path closer to an upstream side than the sheet discharge roller; a motor that rotates at a constant system speed during conveying of sheets to drive the conveying unit; a transmission mechanism that transmits power of the motor to the sheet discharge roller to rotate the sheet discharge roller; and a controller that controls an operation of the transmission mechanism, wherein the transmission mechanism changes a circumferential speed of the sheet discharge roller, and the controller performs speed reduction control of controlling the operation of the transmission mechanism to temporarily reduce the circumferential speed of the sheet discharge roller when a sheet is discharged to the sheet discharge tray.

A sheet conveyance device includes: a first conveyance path configured to allow a sheet to be conveyed along the first conveyance path; a second conveyance path that extends upward from a branch position in the first conveyance path; a third conveyance path that extends downward from the branch position; a first conveyance roller disposed in the second conveyance path and configured to rotate normally and reversely to convey the sheet; a first drive motor disposed below the branch position; and a first belt disposed in a drive transmission path from the first drive motor to the first conveyance roller and configured to transmit a driving force from the first drive motor to the first conveyance roller.

An image reading device includes a first power transmission section configured to transmit a driving force to the input gear, wherein the first power transmission section is configured to transmit the driving force from a first drive source that drives the feed roller to the input gear and furthermore, the first power transmission section includes a one-way clutch that does not transmit the power of the first drive source to the input gear when the first drive source rotates in a first rotation direction, which is a rotation direction during medium feeding, and transmits the power of the first drive source to the input gear when the first drive source rotates in a second rotation direction, which is opposite to the first rotation direction.