An image forming apparatus includes a photosensitive member, a developing roller, first and second motors, a drive-train having a drive switching unit, and a development switching unit. The drive-train transmits a driving force of the first motor to the developing roller. The second motor drives the drive switching unit and the development switching. The drive switching unit switches between a driving force transmission state and a driving force non-transmission state. The development switching unit switches between a developing roller-photosensitive member contact state and a developing roller-photosensitive member separated state, and operates with an operation of the drive switching unit. When the drive switching unit transitions from the non-transmission to the transmission state and a detected magnitude of a current flowing through the first motor has changed, the second motor is stopped before the developing roller is brought into contact with the photosensitive member while driving the first motor.

A development system for an image forming apparatus includes a photosensitive drum having a drive plate to receive a driving force to rotate the photosensitive drum. The drive plate is provided on an end of the photosensitive drum. The development system also includes a developing roller having a clutch mechanism to dampen a force generated when the clutch mechanism engages the drive plate of the photosensitive drum. The clutch mechanism is provided on an end of the photosensitive drum.

An image forming apparatus includes a toner container, a storage part, a cover and an opening/closing mechanism. The toner container includes a shutter. The cover is movable between a closed position for closing the storage part and an opened position for opening the storage part. The opening/closing mechanism closes a supply port by rotating the shutter in accordance with an opening operation for moving the cover to the opened position and opens the supply port by rotating the shutter in accordance with a closing operation for moving the cover to the closed position, in a state where the toner container is attached to the storage part. The toner container includes an interference portion which interferes with the opening/closing mechanism to prevent the toner container from being attached to the storage part in a case where the cover is not moved to the opened position normally.

A drive transmission device is provided with a drive pulley driven by a motor, a driven pulley in which a bulging part crowned in a shape bulging outward in the radial direction is formed over the entire circumference of the outer peripheral surface, a belt wound around the drive pulley and the driven pulley, and a first measurement unit for measuring rotation unevenness of the drive pulley. The drive pulley has a uniform diameter in the axial direction which is a smaller diameter than that of the driven pulley. The belt is bent and deformed along the bulging part of the driven pulley so that the axial center portion is expanded outward the axial end portion. The axial end of the belt contacts the outer peripheral surface of the drive pulley, but does not contact the outer peripheral surface of the driven pulley.

A motor control apparatus excites an excitation phase targeted for excitation among a plurality of excitation phases of a motor. The motor control apparatus, in a state in which a rotor of the motor is stopped, excites an excitation phase corresponding to a stop position of the rotor among the plurality of the excitation phases, and measures a physical quantity which changes in accordance with an inductance of at least one of a plurality of coils configuring the plurality of excitation phases. The motor control apparatus estimates a temperature of the rotor from a measurement value of the measured physical quantity, and decides a parameter value for control of the motor based on the estimated temperature.

A developing cartridge may include: a casing; a developing roller extending in a first direction; a developing-roller gear; a coupling including a coupling gear; a first idle gear; a second idle gear; an agitator; a first agitator gear; and a protrusion. The developing-roller gear, the coupling, the first idle gear, the second idle gear, the first agitator gear, and the protrusion may be positioned at an outer surface of the casing. The protrusion may be positioned between a first axis of the coupling and a third axis of the first agitator gear in a second direction connecting the first and third axes. The protrusion may be positioned outside an addendum circle of the developing-roller gear, an addendum circle of the coupling gear, an addendum circle of the first idle gear, and an addendum circle of the second idle gear. The first agitator gear may be spaced apart from the protrusion in the first direction.

A photosensitive drum unit to which a coupling member 200 is easily mounted is provided. A drum flange 250 is fixed to one end portion of a cylinder 20A having a photosensitive layer at a peripheral surface. The coupling member 200 is inserted into the drum flange 250. Finally, a closing member 230 is mounted to the drum flange 250.

There is provided an end member which is disposed in an end portion of a columnar rotating body mounted on an image forming apparatus main body, comprising: a tubular bearing member; and a shaft member held by the bearing member, in which the shaft member includes a rotating shaft which oscillates within a range of 18° or less with respect to a direction along an axis of the bearing member, a rotating force receiving member which is disposed in one end portion of the rotating shaft and is provided with an engaging member which is engaged with a driving shaft of the image forming apparatus main body, and a regulating member which is engaged with or disengaged from the rotating shaft or the rotating force receiving member by pressing, and switches a posture in which the engaging member is engaged with the driving shaft and a posture in which the engaging member is not engaged with the driving shaft.

A conveying roller unit comprises a first unit, a second unit, and a lock mechanism. The first unit comprises: a roller section; and a hollow cylindrical holder section. The second unit can be removably mounted to the first unit, and comprises: a second connection section; a rod section inserted into the holder section. The lock mechanism includes: a first engagement section provided on the inner circumferential surface of the holder section; a second engagement section provided on the outer circumferential surface of the rod section; and a urging member for pressing the second unit in the direction in which the rod section comes out of the holder section. The urging member maintains the first engagement section and the second engagement section in an engaged state and restricts the position of the second unit relative to the first unit in both the circumferential direction and the rotation axis direction.

A drive transmission device includes a first rotary body coupled to a drive source, a second rotary body that receives a drive force transmitted from the drive source, a coupling that couples the first rotary body and the second rotary body, and a spring that presses the coupling toward the second rotary body. Each of the first rotary body and the second rotary body includes a plurality of grooves. The coupling has axially opposed first end and second end coupled to the first rotary body and the second rotary body, respectively. The coupling includes a plurality of couplers on a circumferential surface of each of the first end and the second end. The plurality of couplers are axially movable into and out of the plurality of grooves of each of the first rotary body and the second rotary body. The coupling has a spherical end face at the second end.