A rotator driver includes an endless rotator having an end face in a longitudinal direction thereof. A slide aid contacts an inner circumferential face of the endless rotator. A lubricant is applied between the slide aid and the inner circumferential face of the endless rotator. An end face contact member contacts the end face of the endless rotator and has an end face opposed face contacting the end face of the endless rotator and an opposite face being opposite to the end face opposed face. A helical gear is mounted on the opposite face of the end face contact member. The helical gear has teeth being oriented to generate a force that moves the end face contact member toward the end face of the endless rotator as the helical gear rotates. The helical gear has an outer diameter being not greater than an outer diameter of the endless rotator.

An image forming apparatus includes a developing roller, a motor, a motor control portion configured to control the motor, a drive switching unit configured to switch between transmission and non-transmission of the rotational driving force of the motor relative to the developing roller, a current detection portion configured to detect a current value of a current to the motor, and an acquisition unit configured to acquire information relating to a rotation amount of the developing roller. The acquisition unit is configured to acquire the information relating to the rotation amount of the developing roller on the basis of a transmission timing at which the rotational driving force is allowed to be transmitted to the developing roller by the drive switching unit and a non-transmission timing at which the rotational driving force is prevented from being transmitting to the developing roller by the drive switching unit.

An image forming apparatus including a motor, a photosensitive drum, a developing roller, a main memory, and a controller. The controller is configured to perform storing a first rotation number and a second rotation number in the main memory. The first rotation number is the rotation number of the photosensitive drum rotated in a first state where the photosensitive drum rotates and the developing roller is stopped. The second rotation number is the rotation number of the photosensitive drum rotated in a second state where the photosensitive drum rotates and the developing roller rotates. The controller is further configured to perform, in a case where the photosensitive drum rotates, determining a total deterioration quantity of the photosensitive drum which is a cumulative deterioration quantity of the photosensitive drum based on the first rotation number and the second rotation number.

An image forming apparatus includes: a photosensitive drum; a developing roller; a separation mechanism configured to switch a state of the photosensitive drum and the developing roller between a contact state and a separation state; a main memory storing therein a first rotation number and a second rotation number; and a controller configured to perform calculating a deterioration quantity of the photosensitive drum based on the first rotation number and the second rotation number in the main memory. A surface of the developing roller contacts a surface of the photosensitive drum in the contact state, whereas the surface of the developing roller is separated from the surface of the photosensitive drum in the separation state. The first rotation number is the number of rotations of the photosensitive drum in the contact state, and the second rotation number is the number of rotations of the photosensitive drum in the separation state.

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.

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.

An image forming apparatus includes a driving unit including a driving source, a drive gear, a first support member that holds the driving source and includes a first support portion that supports one end portion of a rotation shaft of the drive gear, and a second support member that includes a second support portion that supports another end portion of the rotating shaft. The first support member includes a fastening hole disposed in a projection plane obtained by projecting the second support portion in the rotation axis direction of the drive gear. The second support member is disposed upstream of the first support member in a fastening direction, and includes a mounting portion extending so as to be in contact with the first support portion in the projection plane, the mounting portion including an attachment hole, the attachment hole being disposed at a position overlapping the fastening hole.

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.

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.