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 includes a photosensitive member, a charging member, an exposure unit, a developing unit including a developing member, a motor, a contact and separation unit, a controller, an acquiring portion for acquiring information on a switching time which is a time required for switching a state of the developing member from a separated state to a contact state by executing a contact operation by the contact and separation unit, and a setting portion for setting, on the basis of the information on the switching time acquired by the acquiring portion, a start timing which is a timing when the contact operation by the contact and separation unit is started in a preparation operation and which is a timing before a region on the photosensitive member exposed to light in a light emission period reaches a developing position.

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 estimation unit estimates a first coil temperature in a state where the motor is stopped, and a second coil temperature in a state where the motor is driven, and the control unit controls the driving of the motor based on the first coil temperature and the second coil temperature.

An example image forming apparatus includes a power device, a photosensitive drum, a transfer device to remove remaining toner based on a cleaning bias voltage, an optical sensor to detect remaining toner, and a processor to adjust the cleaning bias voltage based on a set offset bias voltage. The processor may change a surface potential of the photosensitive drum to a voltage of a set pattern using the power device, acquire a size ratio of a periodic component based on a frequency of a signal detected from the remaining toner using the optical sensor, and, based on the acquired size ratio of the periodic component being greater than or equal to a set size ratio, adjust the cleaning bias voltage based on an offset bias voltage corresponding to the size ratio of the periodic component and provide the adjusted cleaning bias voltage to the transfer device to remove remaining toner.

An image forming apparatus includes a developing roller, a photoconductor drum, a density detector, a current detector, and a controller. The developing roller carries a toner. The photoconductor drum carries a toner patch. The density detector detects toner density of the toner patch. The current detector detects developing current flowing to the toner patch. The controller calculates an inclination of an approximate straight line approximating a relation between the toner density and the developing current. The developing roller develops three or more toner patches, different in toner density and different in developing current from one another, on the photoconductor drum. The controller calculates the inclination, using different mathematical expressions depending on whether three toner patches or four toner patches are provided.

Examples of methods are described herein. In some examples, a method includes calculating a first cost function measure based on band defects in an image. In some examples, the method also includes calculating a second cost function measure based on the band defects and a synthetic band. In some examples, the method further includes detecting a missing band based on a comparison of the first cost function measure and the second cost function measure.

An example image forming apparatus includes a charger, a developing device, a sensor, and a controller. The charger may apply a plurality of charging voltages to a photoconductor, the plurality of charging voltages having different magnitudes and respectively corresponding to a plurality of area sections constituting a test pattern and the developing device may supply a developer to the photoconductor. The sensor may sense an image formed by the supplied developer and corresponding to the test pattern. The controller may determine a remaining lifetime of the photoconductor based on the image corresponding to the test pattern.

According to at least one embodiment, an image forming apparatus includes a voltage measuring device, a fixing device, and a controller. The voltage measuring device measures an input voltage. The fixing device includes a heater that heats a sheet. When the measured voltage becomes equal to or greater than a threshold value, the controller determines a heating timing of the heater based on the voltage and activates the heater at the determined heating timing.

An image forming apparatus includes an image bearing member, a charging member, a development member, a transfer member, a charging voltage application unit, a development voltage application unit, and a control unit. The development member collects toner that remains on a surface of the image bearing member after a toner image is transferred from the image bearing member surface to transfer material. The control unit controls application of a development voltage to apply, to the development member in a cleaning operation, a development voltage having a polarity that is opposite to a normal polarity, and controls application of a charging voltage to apply, to the charging member, a charging voltage having the normal polarity such that a potential difference formed at a charging portion between the applied charging voltage and a surface potential formed at the image bearing member surface is lower than or equal to a discharge start voltage.