A developing cartridge includes a casing, a developing roller, a shaft, a tubular member, an elastic member, and a gear. The tubular member is rotatable about the shaft and is movable from a first position and a second position. The tubular member at the second position is farther from an outer surface of the casing in an axial direction than at the first position. The gear is rotatable about the shaft from a first rotational position to a second rotational position. In case where the gear is at the first rotational position, the gear engages with the tubular member and the tubular member is rotatable together with the gear at the first position. In a case where the gear is at the second rotational position, the engagement of the gear with the tubular member is released and the tubular member stops rotating at the second position.

An image forming apparatus member includes a surface layer containing a Si-atom containing polymer as a major component. The dispersive component of the surface free energy of the surface layer is 25 mN/m or less, the dipole component of the surface free energy of the surface layer is 5 mN/m or less, and the hydrogen bonding component of the surface free energy of the surface layer is 5 mN/m or less.

A pixel clock generating device includes a high-frequency clock generator, a comparer, a pixel clock generator, and a value switcher. The high-frequency clock generator is configured to generate a high-frequency clock. The comparer is configured to measure a time interval between a leading-end synchronizing signal and a trailing-end synchronizing signal in a main scanning and calculate an error between the time interval and a target value. The pixel clock generator is configured to generate a pixel clock based on the high-frequency clock and a pixel clock frequency and correct the pixel clock based on the error. The value switcher, including a plurality of groups of values with which the pixel clock is generated, is configured to switch between the plurality of groups of values according to a switching signal after the trailing-end synchronizing signal is inputted, the comparer calculates the error, and the pixel clock generator corrects the pixel clock.

An image forming apparatus includes a photosensitive member that rotates at a first speed, an intermediate transfer member that rotates at a second speed lower than the first speed, and a collecting member disposed in a state in which a fixed surface is pressed against the rotating intermediate transfer member. The collecting member collects toner remaining on the intermediate transfer member after a toner image is secondarily transferred from the intermediate transfer member to a transfer material.

A sheet discharging device includes a stacking portion configured to stack a sheet; a discharging portion configured to feed the sheet so as to be discharged to the stacking portion, wherein the discharging portion includes a first roller configured to feed the sheet and a second roller provided so as to be contactable to a sheet surface opposite from another sheet surface to which the first roller is contactable to; and an electrically discharging member configured to electrically discharge the sheet in contact with the sheet fed by the discharging portion. As viewed in a widthwise direction perpendicular to a discharging direction of the sheet, the electrically discharging member is provided so as to extend through between rotational axes of the first and second rollers in the discharging direction of the sheet.

An image heating apparatus includes an endless belt for heating a toner image on a sheet; a first detector for detecting a temperature of one longitudinal end portion of the endless belt; a second detector for detecting a temperature of the other longitudinal end portion of the endless belt; and a controller for controlling whether or not notification of generation of an error is provided on the basis of a change amount per unit time of a difference in detection temperature between the first detector and the second detector.

In a case where a collection mode in which a exposure unit forms a first potential on a photosensitive member and a developing unit collects discharging toner discharged from the developing unit to a position where the first potential is formed is executed, a potential forming unit forms, on an intermediate transfer member, a potential same as a normal charging polarity of toner and an absolute value greater than an absolute value of the first potential, and a charging power supply applies, to a charging member, a voltage having a polarity same as the normal charging polarity and an absolute value greater than an absolute value of the first potential.

An optical scanning apparatus includes first and second light sources, a rotatable polygonal mirror, a motor, first and second mirrors, first and second lenses, and a casing. Within a mounting range, a top wall of an accommodating portion is provided with at least one projection projecting toward an opening of the accommodating portion. The projection extends from a first side wall to a second side wall of the accommodating portion. The top wall includes a recess formed opposite from the projection, and is free from a portion projecting toward the opening over a range from the first side wall to the second side wall, other than the projection in the mounting range. A free end portion of the projection is in a position remoter from the opening than a reflecting surface of the rotatable polygonal mirror is with respect to a rotational axis direction of the motor.

An image forming apparatus includes a control portion configured to perform a cleaning operation including: a first step of causing a developer, which has a reversed polarity and is attracted to a surface of a charging roller, to have a normal polarity under a state in which the developer bearing member is separated from the image bearing member with the contact/separation unit; and a second step of collecting the developer, which has the normal polarity and is attracted to the surface of the image bearing member, to the developer bearing member, by rotating the image bearing member and the developer bearing member under a state in which the developer bearing member is brought into contact with the image bearing member with the contact/separation unit after performing the first step.