A drive device that drives a detachable unit detachably attached to an image forming apparatus includes a drive coupling, a rotary shaft, a relay member, a contact member, and a compression spring. The drive coupling contacts and separate from a driven coupling of the detachable unit along with movement of the detachable unit. The relay member transmits rotation force of the rotary shaft to the drive coupling to rotate together. The compression spring has an axial end contacting the contact member disposed away from the driven coupling from the relay member and another axial end contacting the relay member. The drive coupling includes an outer circumferential restrictor restricts radial movement of the compression spring. The relay member includes an inner circumferential restrictor restricts radial movement of the compression spring.

A transmission unit transmits driving force to be supplied from a motor to a roller pair. A switching unit acts on the transmission unit to switch a rotation direction of the roller pair by the driving force between a normal rotation and a reverse rotation. A control unit controls a rotation speed of the motor to convey the sheet at a second conveyance speed in a part of a first time period. The second conveyance speed is lower than a first conveyance speed. The first conveyance speed is a conveyance speed when the sheet is conveyed in the image forming unit. In the first time period the sheet having the image formed on the first surface is conveyed in a first direction. In a second time period the sheet is conveyed in a second direction.

An image forming apparatus includes: a pair of transport rollers that nip and transport a recording medium; an image forming device that is disposed on the downstream side of the pair of transport rollers in a recording-medium transport direction and forms an image on the recording medium; a pair of fixing members that are disposed on the downstream side of the image forming device in the recording-medium transport direction and fix the image formed on the recording medium while nipping and transporting the recording medium; a single driving source that rotationally drives both the pair of transport rollers and the pair of fixing members; and a releasing device that stops rotational driving of the pair of transport rollers by the driving source at a timing when the recording medium is transported while being nipped both between the pair of transport rollers and between the pair of fixing members.

An image forming apparatus includes an apparatus body including an image forming unit, a unit detachably attached to the apparatus body, a first rotary member provided in the unit, a second rotary member provided in the apparatus body and configured to be coupled with and decoupled from the first rotary member by being moved in a rotation axial direction of the first rotary member, and a restriction member provided in the apparatus body and movable to a first position and a second position. The restriction member includes an engaging portion configured to engage with the second rotary member and is configured to move the second rotary member by the engaging portion so that the second rotary member is decoupled from the first rotary member along with a move of the restriction member from the first position to the second position.

A belt unit includes: a drive roller; a drive shaft having an axis defining an axial direction and rotatable together with the drive roller about the axis; a bearing rotatably supporting one end portion of the drive shaft; a driven shaft; a driven roller rotatable together with the driven shaft; an endless belt looped over the drive roller and the driven roller under tension; a first frame; and a second frame spaced away from the first frame in the axial direction. The first frame includes: a facing section supporting one end portion of the driven shaft; and a bearing holder holding the bearing. The second frame rotatably supports another end portions of the drive shaft and the driven shaft. The bearing holder is positioned closer to the second frame than the facing section is to the second frame in the axial direction.

A process cartridge comprises an electrophotographic photosensitive drum having a photosensitive layer at a peripheral surface thereof, and process means actable on the electrophotographic photosensitive drum. The process cartridge also includes a coupling member capable of taking a rotational force transmitting angular position for transmitting the rotational force for rotating the electrophotographic photosensitive drum to the electrophotographic photosensitive drum and a disengaging angular position in which the coupling member is inclined away from the axis of the electrophotographic photosensitive drum from the rotational force transmitting angular position.

A driving device includes: a first driving source; a second driving source; a first gear to which a driving force is transmitted from the first driving source; a second gear to which a driving force is transmitted from the second driving source; a third gear that engages with the first gear and the second gear; and a fixation shaft that pivotally supports the third gear, the fixation shaft being disposed such that a center of the fixation shaft, a rotation center of the first gear and a rotation center of the second gear are disposed on a straight line in which the fixation shaft is provided through the third gear; and a hole having a diameter for compensating eccentricity of the first gear, the second gear and the third gear is formed in the third gear.

An example image forming apparatus includes a main body, a driving motor rotatable in a first direction to provide a driving force to a developing cartridge and rotatable in a second direction opposite to the first direction, and a support assembly to, based on the developing cartridge being mounted to the main body, provide the driving force of the driving motor in the first direction to the mounted developing cartridge, and detach the mounted developing cartridge from the main body using the driving force of the driving motor in the second direction.

A developing cartridge includes a first gear, a second gear, and a protrusion. The first gear is rotatable about a first axis extending in a predetermined direction. The second gear is configured to engage with the first gear and rotatable about a second axis extending in the predetermined direction. The protrusion extends in the predetermined direction and circularly movable together with rotation of the second gear. The first gear is movable in a direction away from the second gear from a first position to engage with the second gear to a second position to disengage from the second gear.

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.