An image forming apparatus includes a photosensitive member, a charging member, an exposing device, a developing device, a transfer member, a brush, a voltage applying portion, and a control portion controlling a surface potential of the photosensitive member at the brush contacting position. When a value of subtracting a value of the surface potential of the photosensitive member in the brush contacting position from a value of the brush voltage is defined as a contacting position potential difference, the control portion controls the surface potential of the photosensitive member in the brush contacting position so that the contacting position potential difference is changed from a first potential difference to a second potential difference in a predetermined direction which is either one of an increasing direction or a decreasing direction, and then the contacting position potential difference is changed from the second potential difference to a third potential difference in the predetermined direction.

An image forming apparatus according to aspects of the present disclosure includes a cover, an interlocking mechanism, a sensor, a separation mechanism, a controller. In a state where the cover moves from a closed position to an open position while no power is supplied to the controller, a state of the interlocking mechanism changes from a first state to a second state. In a state where the sensor does not detect that the interlocking mechanism is in the second state when power supply to the controller is started, the separation mechanism keeps the developing roller located at a separation position at the separation position. On the other hand, in a state where the sensor detects that the interlocking mechanism is in the second state when power supply to the controller is started, the separation mechanism moves the developing roller located at a contact position to the separation position.

A print apparatus component to be cleaned is rotated about a rotational axis. A cleaning element having a cleaning surface in contact with the print apparatus component is rotated. The cleaning element is oscillated in a direction parallel to the rotational axis. Rotation and oscillation of the cleaning element are varied according to a predetermined function to remove a residue from the print apparatus component.

An example developing device includes a developing roller, a regulation blade to regulate a thickness of a toner layer attached to an outer circumference of the developing roller, a blade bracket for supporting the regulation blade, and an inner duct including an air supply port and extending in a longitudinal direction of the developing roller to form a flow path of air to cool the blade bracket.

An imaging system includes a storage container, a separating device and a restoring device. The storage container stores a developer including carrier and toner having restoring properties. The separating device separates the developer in the storage container into the carrier and the toner. The restoring device restores properties of the carrier and the toner generated by the separating device.

A cartridge for an electrophotographic image forming apparatus includes a developing roller, a rotatable member for transmitting a rotational force to the developing roller, a coupling member, and a frame. The coupling member is capable of moving between a first coupling member position in which the coupling axis is substantially coaxial with the rotational axis of the rotatable member and a second coupling member position in which the coupling axis is not coaxial with the rotational axis of the rotatable member. When the frame is in a first frame position, the coupling member is in the first coupling member position and a rotational force receiving portion of the coupling member engages with a rotational force applying portion of the apparatus, and, when the frame is in the second frame position, the coupling member is in the second coupling member position and the rotational force receiving portion engages with the rotational force applying portion.

An image forming apparatus includes a motor configured to rotationally drive an image bearing roller and a developer bearing roller at a first peripheral velocity ratio and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio. A development contrast formed between a developing bias to the developer bearing roller and a light-part potential formed on the image bearing roller in a case where a development operation is performed at the second peripheral velocity ratio is larger than a development contrast formed between the developing bias to the developer bearing roller and the light-part potential formed on the image bearing roller in a case where the development operation is performed at the first peripheral velocity ratio.

In an endless belt, the absolute value of an electrostatic capacitance C and the absolute value of an alternating-current resistance Z when an alternating voltage of 1 Vp-p is applied in a frequency range of from 10000 Hz to 0.1 mHz from a high frequency side satisfy Formula (1) below, and an alternating-current resistance Z.sub.0.63 when an alternating voltage of 1 Vp-p with a frequency of 0.63 Hz is applied satisfies Formula (2) below. Moreover, an alternating-current resistance Z.sub.630 when an alternating voltage of 1 Vp-p with a frequency of 630 Hz is applied satisfies Formula (3) below:

log.sub.10 C≤3.18×log.sub.10 Z−30.27;  Formula (1):

6.3≤log.sub.10 Z.sub.0.63≤6.9; and  Formula (2):

9.1≤log.sub.10 Z.sub.630≤9.9.  Formula (3):

An imaging system includes a developing roller connected to a supply channel to supply a developing agent and to transfer toner in the developing agent to a photosensitive drum at a supply position, a regulation member located adjacent to the developing roller at an upstream side of the supply position to restrict a thickness of the developing agent; and a casing that forms a release chamber in the periphery of the developing roller between an upstream side of the regulation member and a downstream side of the supply position. The release chamber includes an outlet to discharge scattered toner to an inlet of the supply channel.

A developing device includes a case, a developer holder, a suction duct and a carrier catcher. The case accommodates a developer containing a toner and a carrier. The developer holder is disposed so as to face an image holder disposed outside the case and supplies the developer to the image holder. The suction duct sucks and collects a scattered toner floating in a space around the developer holder. The carrier catcher is formed in a vertical direction and disposed on a lower surface of a path of the suction duct.