A medium processing device includes a processor, a feed roller, a motor, a motive force transmission gear that transmits motive force of the motor t6 the feed roller, a switching unit that is configured including a main gear and a sub gear that meshes with the main gear and moves in planetary motion around the main gear, and that switches accompanying rotation direction switching of the main gear between a meshed state and a disengaged state between the sub gear and the motive force transmission gear, a load detection unit that detects load of the motor, and a controller. The controller controls the motor and the processor according to the load detected by the load detection unit at switching of the sub gear from the disengaged state to the meshed state.

A sheet conveying device includes a drive device, a conveyance device, an optical unit, a white reference member, and a transmission device. The drive device generates a driving force. The conveyance device conveys a sheet by a rotary driving force of the drive device. The optical unit includes an image reading unit that extends in a longitudinal direction thereof along a widthwise direction orthogonal to a direction of conveyance of the sheet, applies light to the sheet, and reads light reflected from the sheet with an image sensor. The white reference member extends in the longitudinal direction of the image reading unit and is read by the image reading unit. The transmission device transmits the driving force generated by the drive device to rock the optical unit in the widthwise direction. The transmission device includes a rocking member that rocks the optical unit in a longitudinal direction thereof.

The apparatus includes a first clutch and a second clutch. The first clutch transmits rotation of the driving unit in a first rotation direction to the first feeding device without transmitting rotation of the driving unit in a second rotation direction that is reverse to the first rotation direction to the first feeding device. The second clutch transmits the rotation of the driving unit in the second rotation direction to the conveyance device and the double-side printing conveyance device and without transmitting the rotation of the driving unit in the first rotation direction to the conveyance device and the double-side printing conveyance device. The third transmission path is configured to transmit the rotation of the driving unit to a conveyance device. The fourth transmission path is configured to transmit the rotation of the driving unit to a double-side printing conveyance device.

A rotary arm restricts the rotation of a first sun gear or a second sun gear according to forward/reverse rotation drive of sheet discharge rollers. As a result, a rotating direction of a transmission gear coupled to the sheet discharge rollers is switched. If 1A denotes a pressure angle of gear teeth of a gear portion of the first sun gear and 2A denotes a pressure angle of gear teeth of a first planetary gear, a relationship of 2A+0.51A2A+1.5 is satisfied.

An axial end of an output shaft facing toward an input shaft has a first hole that is concentric with the output shaft and that axially extends to a predetermined depth. An axial end of the input shaft facing toward the output shaft has a second hole that is concentric with the input shaft and that axially extends to a predetermined depth. A connection pin is inserted in the first hole and the second hole to connect the first hole and the second hole. When the output shaft and the input shaft axially approach each other, the connection pin interposed between the output shaft and the input shaft allows the output shaft and the input shaft to avoid coming into contact with each other.

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 rotary arm restricts the rotation of a first sun gear or a second sun gear according to forward/reverse rotation drive of sheet discharge rollers. As a result, a rotating direction of a transmission gear coupled to the sheet discharge rollers is switched. If 1A denotes a pressure angle of gear teeth of a gear portion of the first sun gear and 2A denotes a pressure angle of gear teeth of a first planetary gear, a relationship of 2A+0.51A2A+1.5 is satisfied.

A sheet supply apparatus detachably attached to an image forming apparatus is configured to receive a drive force from the image apparatus to supply sheet to the image forming apparatus. The sheet supply apparatus includes a sheet supply tray, a sheet supply roller, a first transmission mechanism configured to transmit a drive force from the image forming apparatus to the sheet supply roller, a second transmission mechanism including an output member and configured to transmit a drive force supplied from the image forming apparatus to the output member, a clutch mechanism configured to intermittently transmit a drive force from the image forming apparatus to the second transmission mechanism, a latch member pivotable between a restriction position and an allowance position, a change cam, a sector gear, a rotational force applying member, an engaging member, a first engagement portion, a second engagement portion, and an electromagnetic solenoid.

A sheet conveyer, including a tray, a pickup roller, a separator roller, a separator pad, a driving source, a roller holder with an arm, an engagement member engageable with the arm, a load applier lever, and a first urging member coupled with the load applier lever, is provided. The load applier lever is movable between a first position, wherein the load applier lever supports the first end of the first urging member at a position where the first urging member causes the engagement member to be urged against the arm and to apply a load that acts in a direction to cause the pickup roller to be pressed against the sheets to the arm; and a second position, wherein the load applier lever supports the first end of the first urging member at a position where the first urging member is in the natural length thereof.

An image forming apparatus includes: an image-forming mechanism; a reconveying roller; an electric motor; and a transmission mechanism. The transmission mechanism is configured to operate in one of a reverse-rotation transmission mode for reversing a direction of a rotational force received from the electric motor to transmit the reversed rotational force to the reconveying roller and a normal-rotation transmission mode for transmitting the rotational force to the reconveying roller without reversing the direction of the rotational force. The transmission mechanism includes an interrupting unit for interrupting transmission of a rotational force from the reconveying roller to the electric motor at least when a sheet is being conveyed in the image-forming mechanism. The transmission mechanism is configured to interrupt transmission of the rotational force received from the electric motor to the reconveying roller when a sheet is being conveyed in the image-forming mechanism.