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.

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 and charging, development and transfer of the photoreceptor, wherein, 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 sheet feeding device includes a sheet feeding roller, a following roller, a rotational speed detection part, and a control part. The rotational speed detection part is configured to detect a rotational speed of the following roller. The control part is configured to accelerate a rotation of the sheet feeding roller and to adjust a sheet interval. The control part obtains a rotational rate of the following roller to the sheet feeding roller based on the rotational speed of the following roller, obtains an actual linear velocity of the sheet based on the rotational rate of the following roller and a theoretical linear velocity of the sheet after accelerating the rotation of the sheet feeding roller, and then adjusts the sheet interval based on the actual linear velocity of the sheet.

An image forming apparatus includes an image forming part, a toner storage part, a toner conveyance part, a drive motor and a control part. The image forming part forms an image on a sheet using a toner. The toner storage part stores the toner replenished to the image forming part. The toner conveyance part conveys the toner. The drive motor generates a drive force by which the toner conveyance part conveys the toner. The control part generates a control signal for controlling the drive motor, based on information showing a rotational speed of the drive motor. The control part executes a determination processing for determining whether a driving of the drive motor is stopped, based on the control signal.

A sheet feeding device includes a sheet feeding roller, a following roller, a rotational speed detection part, and a control part. The rotational speed detection part is configured to detect a rotational speed of the following roller. The control part is configured to accelerate a rotation of the sheet feeding roller and to adjust a sheet interval. The control part obtains a rotational rate of the following roller to the sheet feeding roller based on the rotational speed of the following roller, obtains an actual linear velocity of the sheet based on the rotational rate of the following roller and a theoretical linear velocity of the sheet after accelerating the rotation of the sheet feeding roller, and then adjusts the sheet interval based on the actual linear velocity of the sheet.

An image forming apparatus includes an image forming part, a toner storage part, a toner conveyance part, a drive motor and a control part. The image forming part forms an image on a sheet using a toner. The toner storage part stores the toner replenished to the image forming part. The toner conveyance part conveys the toner. The drive motor generates a drive force by which the toner conveyance part conveys the toner. The control part generates a control signal for controlling the drive motor, based on information showing a rotational speed of the drive motor. The control part executes a determination processing for determining whether a driving of the drive motor is stopped, based on the control signal.

At the time of an end of an image forming job (YES of S1), a controller causes a blade and a developing roller to be separated from a photosensitive drum (S2). At that time, the controller controls separation timing of the belt and the developing roller so that the developing roller is separated from the photosensitive drum before a surface position of the photosensitive drum contacted to the developing roller at a contact position at the time of a start of separation of the blade from the photosensitive drum reaches a developing position with the separation of the blade. According to this, even when a liquid accumulation reaches the developing position depending on the separation of the blade, the developing roller has already been separated from the photosensitive drum before the liquid accumulation reaches the developing position and therefore, the liquid accumulation is not collected by the developing roller. When the liquid accumulation is not collected by the developing roller, color mixture due to the liquid accumulation does not occur.

At the time of an end of an image forming job (YES of S1), a controller causes a blade and a developing roller to be separated from a photosensitive drum (S2). At that time, the controller controls separation timing of the belt and the developing roller so that the developing roller is separated from the photosensitive drum before a surface position of the photosensitive drum contacted to the developing roller at a contact position at the time of a start of separation of the blade from the photosensitive drum reaches a developing position with the separation of the blade. According to this, even when a liquid accumulation reaches the developing position depending on the separation of the blade, the developing roller has already been separated from the photosensitive drum before the liquid accumulation reaches the developing position and therefore, the liquid accumulation is not collected by the developing roller. When the liquid accumulation is not collected by the developing roller, color mixture due to the liquid accumulation does not occur.

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.

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.