A drive mechanism that drives a rotator to rotate includes a main motor, an assist motor, and processing circuitry. The main motor drives the rotator. The assist motor drives the rotator and assists a drive of the rotator by the main motor. The processing circuitry controls a speed of the main motor so that a rotational speed of the rotator is constant, and controls a motor voltage of the assist motor so that the motor voltage of the assist motor changes according to a change in a motor current of the main motor.

A sheet processing apparatus includes a first guide plate and a second guide plate facing with a given space in a thickness direction and having second and third openings, a sheet conveyance passage between the first and second guide plates, and a sheet conveyor including a drive source, a drive roller, a first driven roller, and a second driven roller. The drive roller protrudes from the first guide plate toward the sheet conveyance passage through the first opening. The first driven roller faces the drive roller and protrudes from the second guide plate toward the sheet conveyance passage through the second opening. The second driven roller protrudes from the second guide plate toward the sheet conveyance passage through the third opening. The second driven roller is disposed at a position shifted from the drive roller in a width direction orthogonal to the sheet conveyance direction and the thickness direction.

A drying device (7) is a drying device which dries a sheet while conveying the sheet. The drying device (7) includes a conveying part (15) which conveys the sheet in a predetermined conveyance direction; a heating part (13) which is arranged above the conveying part (15) and dries the sheet conveyed by the conveying part (15); and a supporting part (17) which supports the conveying part (15) in a heating position where the sheet is heated by the heating part (13), by power supplying, wherein when the power supplying to the supporting part (17) is cut off, a force by which the conveying part (15) is supported in the heating position is weakened, and the conveying part (15) is lowered to a retreating position separated downward from the heating part (13).

A drive mechanism that drives a rotator to rotate includes a main motor, an assist motor, and processing circuitry. The main motor drives the rotator. The assist motor drives the rotator and assists a drive of the rotator by the main motor. The processing circuitry controls a speed of the main motor so that a rotational speed of the rotator is constant, and controls a motor voltage of the assist motor so that the motor voltage of the assist motor changes according to a change in a motor current of the main motor.

A postprocessing device includes a processing tray, a sheet processor, an air blower, an inlet roller pair, and a drive controller. The air blower forms an air layer between an upper face of a first recording sheet already placed on a loading surface of the processing tray, and a lower face of a second recording sheet to be newly placed on the processing tray, by sending air along a transport direction of the recording sheet, from an upstream side in the transport direction toward the loading surface. The drive controller performs an air sending operation, by causing the air blower to send air along the transport direction, before a second recording sheet contacts the upper face of the first recording sheet, and stop sending air before a trailing edge of the second recording sheet in the transport direction passes a nip region defined by the inlet roller pair.

A drying device (7) is a drying device which dries a sheet while conveying the sheet. The drying device (7) includes a conveying part (15) which conveys the sheet in a predetermined conveyance direction; a heating part (13) which is arranged above the conveying part (15) and dries the sheet conveyed by the conveying part (15); and a supporting part (17) which supports the conveying part (15) in a heating position where the sheet is heated by the heating part (13), by power supplying, wherein when the power supplying to the supporting part (17) is cut off, a force by which the conveying part (15) is supported in the heating position is weakened, and the conveying part (15) is lowered to a retreating position separated downward from the heating part (13).

A feeding roller feeds a medium placed at a medium placement portion by forward rotation power supplied from a driving unit. A displacement portion displaces the feeding roller to an abutting position by the forward rotation power supplied from the driving unit and displaces the feeding roller to a separation position by reverse rotation power supplied from the driving unit. A power transmission unit includes a one-way clutch that transmits the forward rotation power, that is supplied from the driving unit, to the feeding roller but does not transmit the reverse rotation power, that is supplied from the driving unit, to the feeding roller.

A drying device (7) is a drying device which dries a sheet while conveying the sheet. The drying device (7) includes a conveying part (15) which conveys the sheet in a predetermined conveyance direction; a heating part (13) which is arranged above the conveying part (15) and dries the sheet conveyed by the conveying part (15); and a supporting part (17) which supports the conveying part (15) in a heating position where the sheet is heated by the heating part (13), by power supplying, wherein when the power supplying to the supporting part (17) is cut off, a force by which the conveying part (15) is supported in the heating position is weakened, and the conveying part (15) is lowered to a retreating position separated downward from the heating part (13).

A sheet processing apparatus includes a first guide plate and a second guide plate facing with a given space in a thickness direction and having second and third openings, a sheet conveyance passage between the first and second guide plates, and a sheet conveyor including a drive source, a drive roller, a first driven roller, and a second driven roller. The drive roller protrudes from the first guide plate toward the sheet conveyance passage through the first opening. The first driven roller faces the drive roller and protrudes from the second guide plate toward the sheet conveyance passage through the second opening. The second driven roller protrudes from the second guide plate toward the sheet conveyance passage through the third opening. The second driven roller is disposed at a position shifted from the drive roller in a width direction orthogonal to the sheet conveyance direction and the thickness direction.