An electrophotographic image forming apparatus which sequentially performs charging, exposure, development, transfer and cleaning on each surface portion of a photoreceptor during rotation includes a cleaning blade configured to scrape off toner from the surface of the photoreceptor, a detecting unit configured to detect a rotation angle of the photoreceptor, and a control unit configured to control each of a start process and an end process of rotation of the photoreceptor. The control unit is also configured to control charging, development and transfer of the photoreceptor. In the end process, the control unit estimates a position of a surface portion of the photoreceptor, at which a charged state caused by a peeling discharge remains even after the stop of the photoreceptor, from the rotation angle from the time of start of deceleration of the photoreceptor to the time of stop of the photoreceptor, and adjusts parameters necessary for the next start process or end process.

A toner supply unit for use in an image forming apparatus includes a bottle gear provided on a toner bottle to receive a driving force when the toner bottle is mounted to a mounting portion, and a discharging mechanism provided on the toner bottle to discharge a predetermined amount of toner from a discharging portion with the rotation of the bottle gear. A controller controls the driving force inputted to the bottle gear in a period from input of the driving force to the bottle gear to a predetermined number of rotations of the toner bottle to be smaller than the driving force inputted to the bottle gear at a time when the discharging mechanism first discharges the predetermined amount of toner from the discharging portion after the predetermined number of rotations.

An image forming apparatus includes: an image forming unit configured to form an image pattern on a medium, a predetermined image repeatedly appearing in a first cycle in a sub scanning direction in the image pattern; a density detector configured to optically detect a density of the image pattern in the sub scanning direction; a cyclic image detector configured to detect a feature image having a second cycle corresponding to the first cycle in accordance with a result of the detection; and a state determining unit configured to determine whether a cycle depending on an outer circumference of a rotary member included in the image forming apparatus corresponds to the second cycle when the feature image is detected by the cyclic image detector, and determine that a state of the rotary member has deteriorated when the cycle depending on the outer circumference is determined to correspond to the second cycle.

A toner supply unit for use in an image forming apparatus includes a main body, a driving device supplying a driving force, a controller to control the driving force, and a toner bottle containing toner, dismountably mounted to a mounting portion, and including a discharging portion for discharging the toner. A movable shutter member on the toner bottle moves between a closing position and an opening position for opening the discharging portion, and a bottle gear is provided on the toner bottle and receives the driving force. The driving force supplied to the bottle gear when a discharging mechanism first discharges the predetermined amount of toner from the discharging portion after the shutter member moves to the opening position is smaller than the driving force supplied to the bottle gear during moving of the shutter member to the opening position.

An image forming apparatus includes an image carrier, a motor, a cleaning portion, a measurement processing portion, and a cleaning control portion. The image carrier is configured to carry an electrostatic latent image. The motor is configured to rotate the image carrier. The cleaning portion is configured to clean the image carrier. The measurement processing portion is configured to measure a transition time that is a time required for the motor to transition from a stationary state to a driving state in which the motor rotates at a predetermined speed. The cleaning control portion is configured to control a cleaning time of the cleaning portion or whether or not to cause the cleaning portion to clean the image carrier.

An image forming apparatus includes upstream-side and downstream-side detection parts and a control section. The detection parts are disposed on a moving path of an intermediate transfer belt or a conveyor belt and detect a speed of the belt. The control section performs control to correct color misregistration of images composed of colors to be formed on the intermediate transfer belt or a recording medium conveyed by the conveyance belt on the basis of the detection result. The control unit calculates a difference between the speed detected by the upstream-side detection part and the speed detected by the downstream-side detection part after a predetermined time elapses since the upstream-side detection part detects the speed and performs the control on the basis of the difference. The predetermined time is obtained by dividing a distance between the detection parts by a target speed of the belt.

An image forming apparatus includes a developer accommodating container having a discharge opening for discharging the developer with rotation thereof; a developer receiving device; a driver rotating the container; a detector detecting rotation of the container; an openable member movable between a closing position and an opening position; a moving mechanism for moving the openable member from the closing position to the opening position in a state that the container is being rotated, and to stop a driving force to the openable member after the movement of the openable member to the opening position. A controller operates the driver with a predetermined fixed input value during the openable member moving from the closing position to the opening position and switches the input value on a signal from the detector such that when the openable member is in the opening position, the container rotates at a predetermined speed.

An image forming apparatus includes a transfer portion configured to transfer a toner image onto the sheet, a fixing unit configured to fix the toner image transferred by the transfer portion on the sheet, a detection unit arranged between the transfer portion and the fixing unit in a sheet conveyance direction and configured to detect a bending amount of the sheet nipped by the transfer portion and the fixing unit, and a control unit configured to control a conveyance speed of the sheet conveyed by the fixing unit based on a detection result of the detection unit. The detection unit includes a pivot portion configured to pivot when pressed by the sheet nipped by the transfer portion and the fixing unit, and a rotary encoder configured to output a pulse signal in accordance with a pivot amount of the pivot portion.

An image forming apparatus includes: a plurality of photoreceptors; a plurality of exposure heads provided so as to correspond to the plurality of photoreceptors, respectively, each of the plurality of exposure heads including a plurality of light emitting units configured to emit light for exposing the corresponding photoreceptor, the plurality of light emitting units being arranged along a rotation axis line of the corresponding photoreceptor; and a generation unit configured to generate a line synchronization signal for each of the plurality of exposure heads to control a light emission timing in a rotating direction of the corresponding photoreceptor, the generation unit being configured to adjust a cycle of the line synchronization signal in accordance with each of the plurality of exposure heads.

An image forming apparatus includes: a plurality of photoreceptors; a plurality of exposure heads provided so as to correspond to the plurality of photoreceptors, respectively, each of the plurality of exposure heads including a plurality of light emitting units configured to emit light for exposing the corresponding photoreceptor, the plurality of light emitting units being arranged along a rotation axis line of the corresponding photoreceptor; and a generation unit configured to generate a line synchronization signal for each of the plurality of exposure heads to control a light emission timing in a rotating direction of the corresponding photoreceptor, the generation unit being configured to adjust a cycle of the line synchronization signal in accordance with each of the plurality of exposure heads.