An image forming apparatus includes a photoconductor, a charger, a detection unit, and a determination unit. The charger charges the photoconductor. The detection unit detects an actual charging potential of the photoconductor after the photoconductor is charged by the charger. The determination unit determines one of a plurality of causes related to a charging abnormality of the photoconductor based on a relationship between a standard charging potential of the photoconductor to be obtained by charging by the charger and a charging potential detected by the detection unit.

An image forming apparatus includes image forming units. A controller includes an execution section, a measurement section, and a prediction section. The execution section controls execution of a developer refresh operation in which toner is ejected from a developer bearing member to an image bearing member so that a specific image forming unit replenishes a development device with the toner from the developer bearing member. The measurement section measures respective surface potentials of the image bearing members included in other image forming units while the specific image forming unit is executing the developer refresh operation. The prediction section uses measurement results of the respective surface potentials of the image bearing members included in the other image forming units for a prediction on the surface potential of the image bearing member included in the specific image forming unit.

An image forming apparatus includes a developing cartridge, a drum cartridge, a casing, a connector, and a controller. The drum cartridge includes a photosensitive drum, a drum cartridge memory, a charger, and a cleaner. The charger is configured to charge the photosensitive drum and including a wire and a grid electrode. The cleaner is configured to clean the wire. The connector is configured to be electrically connected to the drum cartridge memory. Information is writable to the drum memory through the connector. The detection circuit board is configured to detect a state of discharge of the charger. The controller is configured to perform: determining whether or not the state of discharge detected by the detection circuit board is abnormal; and writing, in the drum cartridge memory, information representing occurrence of the abnormal discharge through the connector in a case where occurrence of the abnormal discharge is determined.

An image forming apparatus is configured to control a generation circuit to modulate a DC component of a developing voltage based on a first correction component such that a density unevenness is reduced. The image forming apparatus is further configured to restrict the first correction component for modulating the DC component of the developing voltage such that fogging of toner that may occur on a non-exposure region which is not exposed by an exposure unit and adhesion to a photosensitive member of carrier included in a developer are reduced.

A system displays a plurality of display objects respectively corresponding to a plurality of symptoms of an image forming apparatus, receives a selection of one display object from among the plurality of display objects, and displays a screen for receiving, from a user, a value related to a predetermined item to be adjusted to improve a symptom corresponding to the selected display object.

An image forming apparatus includes first, second, and third acquisition processing portions. The first acquisition processing portion acquires the potential value of a charged area, charged by the charging member, on the image-carrying member. The second acquisition processing portion acquires a state value regarding the state of a surface layer of the image-carrying member based on the potential value of the charged area acquired by the first acquisition processing portion and the current value of a charging current flowing through the charging member during formation of the charged area. The third acquisition processing portion acquires the electrical resistance value of the transfer member based on the state value acquired by the second acquisition processing portion, the voltage value of a transfer voltage applied to the transfer member, and the current value of a transfer current flowing through the charged area in response to application of the transfer voltage.

An image forming apparatus includes an image-carrying member, a first acquisition processing portion, and a second acquisition processing portion. An electrostatic latent image is formed on the image-carrying member. The first acquisition processing portion acquires the potential value of the image-carrying member. The second acquisition processing portion acquires the temperature value of the image-carrying member based on the potential value of the image-carrying member acquired by the first acquisition processing portion.

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.

At least one partial measurement region is set in the longitudinal direction in a printable region of a photosensitive drum 3. After the photosensitive drum 3 has been charged to a constant potential with a charging roller 6, different potentials are set in the partial measurement region and a region excluding partial measurement region with a laser scanner 4, partial discharge information of the partial measurement region is detected by discharge information detection unit, and a bias voltage in image formation that is applied to the charging roller 6 is corrected on the basis of the value of the partial discharge information.

An image forming apparatus includes a photoconductor, a charger, a detection unit, and a determination unit. The charger charges the photoconductor. The detection unit detects an actual charging potential of the photoconductor after the photoconductor is charged by the charger. The determination unit determines one of a plurality of causes related to a charging abnormality of the photoconductor based on a relationship between a standard charging potential of the photoconductor to be obtained by charging by the charger and a charging potential detected by the detection unit.