In an image forming apparatus, a process frame is movable into and out of a main casing in a first direction. The process frame includes a first wall and a second wall spaced apart from the first wall in a second direction. A first cartridge is detachably mountable to the process frame in a third direction crossing the second direction. A first electrode protrudes from an outer surface of the first cartridge outwardly in the second direction. In a state where the first cartridge is mounted to the process frame, the first cartridge is positioned between the first wall and second wall of the process frame in the second direction and a portion of the first wall aligns with the first electrode in the third direction such that the portion of the first wall is overlapped with the first electrode as viewed in the third direction.

A high-voltage electrical circuit board is located in a first region that is a region at one side of photosensitive drums in a first direction and outside of the photosensitive drums in the first direction. A first motor drives a conveyance mechanism. A second motor is located in a second region and drives each photosensitive drum. A third motor is located in the second region and drives each developing roller to rotate and to drive a separation mechanism configured to individually move the developing rollers between a contact position and a separation position. A control board is located in the second region. The control board includes a controller configured to control a first applying circuit, the first motor, the second motor, and the third motor. The first motor, the second motor, the third motor, and the control board are located at different positions from one another in the second region.

A controller is configured to control a print engine and a conveyor to form an image on both sides of a sheet. The controller is configured to: in a case where images to be formed on both sides of each of an Nth (N is a positive integer) sheet, an (N+1)th sheet, and an (N+2)th sheet are all monochrome image or all color image, convey the (N+2)th sheet to the print engine and form an image before forming an image on both sides of the (N+1)th sheet; and in a case where the images to be formed on both sides of each of the Nth sheet, the (N+1)th sheet, and the (N+2)th sheet are a mixture of the monochrome image and the color image, convey the (N+2)th sheet to the print engine and form an image after forming an image on both sides of the (N+1)th sheet.

An image forming apparatus includes first and second image forming portions and a belt. The first and second image forming portions include first and second image bearing members, and first and second transferring members, respectively. The belt nips and feeds a recording material between itself and the first image bearing member and between itself and the second image bearing member in a first transferring portion and a second transferring portion, respectively. The first image forming portion is disposed upstream of the second image forming portion in a moving direction of the recording material, and a plurality of members including the first and second image bearing members are integrally assembled and are mountable on or dismountable from a main assembly of the image forming apparatus. A film thickness of a surface of the first image bearing member is larger than a film thickness of a surface of the second image bearing member.

An image forming apparatus includes a cartridge and a main body into which the cartridge is removably installed. The cartridge includes a first unit and a second unit that is movably connected to the first unit. The main body includes a rotating member, a supporting member disposed at a position away from the rotating member, and a swingable member that is pivotally movable about the supporting member and configured to be moved by the rotating member. The swingable member is movable between a first position at which the swingable member is in contact with the second unit and a second position at which the swingable member is retracted from the first position. Installation and removal of the cartridge into and from the main body is enabled in a state where the swingable member is at the first position and is supported by the rotating member.

A cam transmits and blocks light emitted from a light emitting portion. The cam moves to: a first position at which first and second cartridges are attachable to and detachable from a housing; a second position at which a first development roller contacts a first photosensitive drum, the second position being a position at which the cam has moved in a first direction from the first position; and a third position at which the first development roller is separated from the first photosensitive drum and a second development roller is separated from a second photosensitive drum, the third position being a position at which the cam has moved in the first direction from the second position. During an initial operation, based on a detection result of the sensor, a controller determines which of the first position, the second position, and the third position the cam is located at.

An image forming apparatus, having a first photosensitive drum, a second photosensitive drum, a first developing roller, a second developing roller, a first moving mechanism, a second moving mechanism, a driving gear, a motor, a first gear train, a second gear train, and a third gear train, is provided. The first gear train having a first gear transmits a driving force from the motor to the first developing roller. The second gear train having a second gear transmits the driving force from the motor to the second developing roller. The second gear train is provided separately from the first gear train. The third gear train having a third gear transmits the driving force from the motor to at least one of the first moving mechanism and the second moving mechanism. The third gear train is provided separately from the first gear train and the second gear train.

An image forming apparatus includes a plurality of photosensitive members; a scanner unit including light sources, a rotatable polygonal mirror, and reflecting members; and a fixing portion. Parts of the laser beams emitted from the light sources are reflected by the rotatable polygonal mirror toward the fixing device side, and rest parts of the laser beams are reflected by the rotatable polygonal mirror toward a side opposite from the fixing device side. Of the parts of the laser beams reflected by the rotatable polygonal mirror toward the fixing device side, the laser beam reflected toward the reflecting member provided at a position remotest from the rotatable polygonal mirror travels downward relative to a horizontal direction. A rotational axis of the rotatable polygonal mirror is inclined relative to a vertical direction.

An image forming apparatus, configured to operate in first and second modes of which color gamut is different from each other, includes an exposure unit configured to expose a photosensitive drum; a developing roller configured to form a toner image; a detection unit configured to detect density of the toner image transferred to an intermediate transfer member; and a controller configured to adjust the density based on a value of input image data. A dithering process for the controller's controlling of the exposure unit is different depending on whether the operation is in the first mode or the second mode, and in at least a part of the input image data, the density of the toner image formed by the dithering process in the first mode is higher than the density of the toner image formed by the dithering process in the second mode.

An image forming apparatus includes a main body, a drum cartridge removably attached to the main body, and a belt unit removably attached to the main body. The main body includes a drum power supply, a belt power supply, and a controller configured to start supplying power from the drum power supply to a drum memory of the drum cartridge, start supplying power from the belt power supply to a belt memory of the belt unit, stop supplying the power from the drum power supply to the drum memory after starting supplying the power from the drum power supply to the drum memory, and stop supplying the power from the belt power supply to the belt memory after starting supplying the power from the belt power supply to the belt memory.