An image forming apparatus comprising an image bearing member, a developer bearing member, a drive unit for driving the image bearing member and the developer bearing member in varied peripheral speeds, a control unit, a developing voltage application unit, a supply member for supplying a developer to the developer bearing member, and, a supply member voltage application unit, wherein the control unit executes a first image forming mode in which a rotational peripheral speed ratio between surface movement speeds of the developer bearing member and the image bearing member is not more than 1 and a second image forming mode in which the rotational peripheral speed ratio is larger than 1, and, the control unit controls the drive unit so that a difference between developing voltage and supply voltage becomes larger in the second image forming mode than in the first image forming mode.

An image forming apparatus includes two rotators, a driver driving the rotators, a heating device to heat the rotator, a blower blowing air to the heating device, a temperature detector, a recording medium detector, a cover, an open-close detector, and circuitry. The circuitry detects an abnormal state and stops heat generation, determines whether the cover is closed using the open-close detector, controls the blower to blow air when the cover is closed, determines whether the recording medium is in the nip using the recording medium detector, controls the driver to rotate the two rotators when the cover is closed and no recording medium is in the nip, determines whether a temperature detected is equal to or lower than a threshold value before the cover is opened, and controls the blower to decrease an air volume when the temperature detected is equal to or lower than the threshold value.

A plurality of registration data includes control parameter data related to control of an image forming apparatus capable of executing a printing process. A processor, according to input designation information, selects target registration data from the plurality of registration data. Moreover, the processor derives estimated performance according to derivation rules. Furthermore, the processor outputs information about the estimated performance. The estimated performance is performance related to the printing process in a case where it is presumed that the printing process is executed according target parameters. The target parameters are the control parameters of the target registration data.

A driving unit is controlled so that a driving state where an image bearing member is driven with a first potential difference formed between a brush member and the image bearing member at a contact portion where the image bearing member is in contact with the brush member transitions to a stopped state where the image bearing member stops being driven with a second potential difference formed, the second potential difference having an absolute value less than that of the first potential difference.

An image forming apparatus includes a single fan, a first air outlet port disposed so as to supply air sent from the fan to an image surface of the sheet, a second air outlet port disposed so as to supply the air sent from the fan to a surface opposite to the image surface of the sheet, and a control unit configured to control the fan. The control unit includes a first mode of controlling a rotational speed of the fan at a first rotational speed in a case where the sheet is not present in a position facing the first air outlet port and control the rotational speed of the fan at a second rotational speed lower than the first rotational speed in a case where the sheet is present in the position facing the first air outlet port.

An image forming apparatus includes two rotators, a driver driving the rotators, a heating device to heat the rotator, a blower blowing air to the heating device, a temperature detector, a recording medium detector, a cover, an open-close detector, and circuitry. The circuitry detects an abnormal state and stops heat generation, determines whether the cover is closed using the open-close detector, controls the blower to blow air when the cover is closed, determines whether the recording medium is in the nip using the recording medium detector, controls the driver to rotate the two rotators when the cover is closed and no recording medium is in the nip, determines whether a temperature detected is equal to or lower than a threshold value before the cover is opened, and controls the blower to decrease an air volume when the temperature detected is equal to or lower than the threshold value.

An image forming apparatus includes a scanning means provided with a light source, a polygon mirror and a driving means for driving rotation of the polygon mirror; a photosensitive member, a developing means, and a detecting means for detecting a laser light from the light source. A controller controls to execute a light emission operation so that an area including an image forming area of the photosensitive member is irradiated with the laser light. The controller controls to execute a switching operation in which a rotational speed of the polygon mirror is switched from a first speed to a second speed different from the first speed. The controller controls to execute the light emission operation in a state in which the photosensitive member and the developing means are in contact and are rotating, and to execute the switching operation based on a detecting result of the detecting means in the light emission operation.

An image forming apparatus controls the number of rotations of a photosensitive drum based on information related to the use of the photosensitive drum and a suspension time in a rotation operation of rotating the photosensitive drum after a lapse of the suspension time between a first image forming operation of forming an image on a transfer material and a second image forming operation performed after the first image forming operation.

An image forming apparatus includes: a fixing roller configured to fix an image on a sheet with heat, a rotary member configured to form a nip portion with the fixing roller and driven by the fixing roller, a motor configured to drive the fixing roller, a motor control unit configured to control the motor, a current detection unit configured to detect a current value of a current flowing through the motor, a controller configured to: determine whether or not a stick-slip phenomenon has occurred based on the current value; increase a rotation speed of the motor in a case where the stick-slip phenomenon has occurred, decrease the rotation speed of the motor in a case where the stick-slip phenomenon has not occurred.

A timing specifying device includes count processing circuitry to count an input reference clock; and timing control circuitry configured to set a parameter having an integer part and a fractional part in the count processing circuitry. The count processing circuitry counts the reference clock, outputs a timing signal indicating that a time corresponding to an integer value has passed, and counts a value corresponding to the fractional part at a timing at which the timing signal is output. The integer value is a value indicated by the integer part. The count processing circuitry stops counting of the reference clock when a value obtained by counting the value corresponding to the fractional part carries over from a fraction.