An image forming apparatus detects a first current value and a second current value of currents flowing between an image bearing member and a developer carrying member. When a difference between the detected first current value and the detected second current value exceeds a threshold in a state in which the image bearing member and the developer carrying member are rotated and a first developing voltage is applied to the developer carrying member, a controller controls AC voltage applied to the developer carrying member.

An apparatus according to the aspect of the embodiments includes a phase determiner configured to determine a rotational phase of a rotor, a speed determiner configured to determine a rotational speed of the rotor, a controller having a first control mode for controlling the motor by supplying constant currents to windings, and a discriminator configured to discriminate whether a rotation of the motor is abnormal based on the rotational speed when the rotational speed corresponding to a command speed is equal to or higher than a predetermined value in a state where the controller is controlling the motor in the first control mode. When a signal output from the discriminator indicates that the rotation of the motor is abnormal, the controller stops the motor. When the signal output from the discriminator indicates that the rotation is not abnormal, the controller continues a drive of the motor.

A driving device includes: a frame disposed in the driving device to support a driven unit driven by the driving device, the frame including a first portion, a distance from which to an outer wall of an accommodation device that accommodates the driving device is shorter, and a second portion, a distance from which to the outer wall is longer than the distance from the first portion to the outer wall; and a driving unit disposed between the second portion and the outer wall, at least a part of the driving unit being away from the outer wall by the distance between the first portion and the outer wall or more.

According to at least one embodiment, a failure prediction server includes an interface, a memory, and a processor. The interface is configured to communicate with equipment including a component that deteriorates over time. The memory is configured to store measurement data acquired from the equipment. The processor is configured to set a monitoring start condition for failure prediction in the corresponding equipment based on the measurement data acquired as initial data from the equipment, accumulate the measurement data acquired from the equipment in the memory after the monitoring start condition is satisfied, and predict a failure of the component based on the measurement data accumulated in the memory.

An example method of operating an image forming apparatus includes measuring a toner concentration supplied to a developing apparatus and increasing a driving speed of the developing apparatus based on the toner concentration not reaching a target toner concentration. The toner concentration is measured in a state where the driving speed of the developing apparatus is increased, and, based on the toner concentration not reaching the target toner concentration based on the driving speed of the developing apparatus being increased, an operating state of the image forming apparatus is determined based on a remaining amount of toner.

An image forming apparatus includes a plurality of image bearers, a plurality of rotation reference position detectors, and circuitry. Each of the plurality of rotation reference position detectors faces a corresponding image bearer of the plurality of image bearers to detect a rotation reference position of the corresponding image bearer. The circuitry performs, before an operation of rotating the plurality of image bearers, alignment control based on a result of detection performed by the plurality of rotation reference position detectors. The alignment control is control of driving of the plurality of image bearers to acquire a given relationship between the respective rotation reference positions of the plurality of image bearers. The circuitry determines whether to perform the alignment control based on whether the operation of rotating the plurality of image bearers is a function maintenance related operation.

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 is configured to execute image forming processing of forming an image on a sheet. The apparatus includes a photosensitive drum, a fixing device including a heater and a roller, a main motor configured to generate a driving force, a driving mechanism having a connected state in which the driving force is transmittable to both the roller and the photosensitive drum, and a disconnected state in which the driving force is transmittable to the roller but is not transmitted to the photosensitive drum, a temperature sensor configured to detect a temperature of the fixing device, and a controller. In a case where the image forming processing is started, the controller sets the driving mechanism into the disconnected state, rotates the main motor at a preheating speed, and executes preheating processing in which the fixing device is heated by the heater.

An image forming apparatus includes a fixing member that fixes, onto a recording material, a toner image that has been transferred onto the recording material, a recovery roller that recovers toner adhering onto the fixing member, a cleaning unit, and a controller. The cleaning unit includes a cleaning web that cleans the recovery roller, a first roller around which the cleaning web is wound in advance, a second roller that winds the cleaning web supplied from the first roller, and a third roller that presses the cleaning web against the recovery roller to clean the recovery roller. The controller stops a rotation of a rotor of a motor that drives the second roller, in a case where a value corresponding to a torque applied to the rotor exceeds a threshold while the rotor is rotating.

Examples described herein relate to a system consistent with the disclosure. For instance, the system may comprise a printing device including hardware to adjust a velocity of a development unit within the printing device, a memory resource, and a controller in communication with the memory resource to determine an average usage condition of the printing device, wherein the average usage condition is based on at least one of a print coverage and a quantity of pages printed by the printing device, and adjust a velocity of the development unit based on the average usage condition.