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 includes a developing electrode and a supply electrode. The developing electrode includes a first electrical contact in contact with a developing roller shaft, and a second electrical contact positioned closer to the developing roller shaft than a second agitator gear is to the developing roller shaft. The second electrical contact is positioned farther from the developing roller shaft than the first electrical contact is from the developing roller shaft. The supply electrode includes a first electrical contact in contact with the supply roller shaft, and a second electrical contact positioned closer to the developing roller shaft than the second agitator gear is to the developing roller shaft. The second electrical contact of the supply electrode is positioned farther from the developing roller shaft than the second electrical contact of the developing electrode is from the developing roller shaft.

[Task] To further develop conventional technique.

[SOLUTION] An image forming apparatus includes a main assembly; a plurality of process cartridges detachably mountable to the main assembly. The process cartridges each includes a photosensitive member, a first frame rotatably supporting the photosensitive member, a developing member for depositing toner onto the photosensitive member, and a second frame rotatably supporting the developing member and movable relative to the first frame between a developing position for the developing member to deposit the toner onto the photosensitive member and a retracted position in which the developing member is more remote from the photosensitive member than in the developing position. The apparatus further includes a connecting member 201 connecting at least two of the second frames of the process cartridges and removable from at least one of the process cartridges and from the main assembly.

An image forming apparatus, having a cartridge and a main body, is provided. The cartridge has a cartridge-side coupling to transmit a driving force to a drivable member in the cartridge. The cartridge is detachably attached to the main body. The main body includes a body-side coupling movable between a connecting position, at which the body-side coupling is connected with the cartridge-side coupling, and a separated position, at which the body-side coupling is separated from the cartridge-side coupling; a joint cam movable between a first position, at which the joint cam locates the body-side coupling at the connecting position, and a second position, at which the joint cam locates the body-side coupling at the separated position; and a rotator having a dent. The dent allows entry of an end portion of the joint cam there-into when the joint cam is located at the first position.

[TASK] An object of the present invention is to provide an image developing apparatus and a process cartridge with which an image quality can be improved while reducing a number of parts and reducing an amount of remaining developer. [SOLUTION] A process cartridge detachably mountable to an electrophotographic image forming operators includes a developing chamber including a developing roller and a developer supplying roller; a developer accommodating container accommodating the developer provided below the developing chamber with respect to gravity direction, wherein the developer is fed into the developing chamber while being stirred by a feeding member. The developer supplying roller rotates such that a surface thereof moves in the same direction as a surface of the developing roller at a position where the developer supplying roller contacts the developing roller. A surface speed of the developer supplying roller is higher than a surface speed of the developing roller. The developer supplying roller is rotationally driven by receiving a driving force at a position upstream of the developing roller.

A process cartridge includes a photosensitive drum, a developing roller, and a movable lever. The process cartridge also includes a coupling member operatively connected to the developing roller, with the coupling member being movable in response to a movement of the lever. The process cartridge is configured such that, when the process cartridge is oriented with the photosensitive drum and the developing roller positioned at a downward side of the process cartridge, an end of the lever is positioned lower than a rotational axis of the photosensitive drum and a rotational axis of the developing roller.

A process cartridge includes a photosensitive drum, a developing roller, and a movable lever. The process cartridge also includes a coupling member operatively connected to the developing roller, with the coupling member being movable in response to a movement of the lever. The process cartridge is configured such that, when the process cartridge is oriented with the photosensitive drum and the developing roller positioned at a downward side of the process cartridge, an end of the lever is positioned lower than a rotational axis of the photosensitive drum and a rotational axis of the developing roller.

An example image forming apparatus includes a frame, a first shaft supported by the frame, and a first coupler. The first coupler includes a body coupled to one end of the first shaft and a first protrusion protruding from the body in an axial direction of the first shaft, the first protrusion having a first surface and a second protrusion protruding from the first surface. The second protrusion is to lock with a groove to mount a cartridge on the frame, the first shaft is to provide a rotational force in a first rotational direction to rotate the second protrusion of the first coupler and to insert the second protrusion into the groove to lock with the cartridge, and the first surface of the first protrusion of the first coupler is to contact a second surface to transmit the rotational force to the second coupler in the first rotational direction.

A driving-force transmission member includes a coupling portion that includes a driving-force transmission surface and that transmits a driving force to a cartridge coupling, a first helical gear portion that engages with a driven gear of a cartridge to transmit the driving force, and a second helical gear portion that engages with a drive gear to receive the driving force. The portions rotate integrally with each other when the driving-force transmission member rotates about the axis of rotation. The driving-force transmission surface is shaped with a twist in the same direction as the driving-force transmission member. Helical teeth of the first helical gear portion are shaped with a twist in the same direction as the driving-force transmission surface. Helical teeth of the second helical gear portion are shaped with a twist in a direction opposite to the twist direction of the helical teeth of the first helical gear portion.

An image forming apparatus includes a drive device including a first drive transmission passage through which a driving force of a drive source is transmitted to a developer bearer via a first joint and a second drive transmission passage through which the driving force is transmitted to a rotary body via a second joint. The first drive transmission passage and the second drive transmission passage are defined such that one of a first drive transmission ratio to the first joint of the first drive transmission passage and a second drive transmission ratio to the second joint of the second drive transmission passage is an integral multiple of the other of the first drive transmission ratio from the drive source to the first joint of the first drive transmission passage and the second drive transmission ratio from the drive source to the second joint of the second drive transmission passage.

To develop a conventional coupling for transmitting a driving force.

A coupling member is provided with a supporting portion for movable supporting a driving force receiving portion for receiving a driving force.