In a cartridge, a developing roller is configured to rotate around a first rotational axis extending in a predetermined direction and to carry developer thereon, the developing roller having a first end and a second end apart from each other in the predetermined direction, a from-first-to-second direction being defined along the predetermined direction as being directed from the first end to the second end. A developing electrode is formed of a conductive material and is configured to be electrically connected to the developing roller, the developing electrode including a main part and a protruding portion protruding from the main part in the from-first-to-second direction. A detection body is formed of an insulating material and is rotatably supported by the protruding portion, the detection body including a first opening that exposes part of the protruding portion and a covering portion covering part of the protruding portion.

A developer cartridge is described. The developer cartridge detachably mountable on a tandem type photosensitive unit slidable to a drawn-out position and a mounted position with respect to an image forming apparatus body may include a casing; a developer carrier rotatably supported on one end portion of the casing for carrying a developer; a pair of upright portions arranged on another end portion of the casing at an interval from each other in the axial direction of the developer carrier to extend from another end portion of the casing in a detaching direction for the developer cartridge; and an elastically deformable coupling portion extending in the axial direction of the developer carrier for coupling the upright portions with each other.

An image forming apparatus includes process units and developer cartridges; a process unit supporting member; a cartridge supporting member; and a moving mechanism. Each developer cartridge includes a transporting member configured to transport developer to a corresponding process unit. The moving mechanism is configured to move each transporting member between a communicated position, in which developer is transported to the corresponding process unit, and an interrupted position, in which transporting of developer to the corresponding process unit is interrupted. The transporting member positioned in the interrupted position allows the cartridge supporting member to move from an attached position to a withdrawn position and allows the process unit supporting member to be withdrawn, and the transporting member positioned in the communicated position prevents the cartridge supporting member from moving from the attached position to the withdrawn position and prevents the process unit supporting member from being withdrawn.

An image forming apparatus has a main casing including an opening provided at an upper portion of the main casing, a process cartridge attachable to the main casing through the opening, and a top cover movable between an open position where the top cover opens the opening and a close position where the top cover closes the opening. The process cartridge includes a photosensitive drum and a memory provided with a first electrical contact. The top cover supports an LED head configured to emit light to expose the photosensitive drum, and a second electrical contact electrically connected to the first electrical contact in a state where the process cartridge is attached to the main casing and in a state where the top cover is positioned at the close position.

A developer container includes a memory device with a first marker; and a main body with a second marker, the main body being configured to accommodate a developer. The memory device is attached to the main body such that both the first marker and the second marker are visually recognized.

An image forming apparatus configured to form images on a first surface and a second surface of a sheet includes an apparatus body, an image forming unit, a feed tray, and a return unit configured to return the sheet having an image formed on the first surface of the sheet toward the image forming unit. The return unit includes a first guide, a second guide, and an adjuster. The first guide is detachably attached to the second guide and includes a first roller and a positioned portion. The second guide is positioned in the apparatus body and includes a second roller facing the first roller, and a positioning portion configured to contact the positioned portion of the first guide, thereby positioning the first guide relative to the second guide. The adjuster is configured to adjust an orientation of the second guide relative to the apparatus body.

A lens unit includes a first lens array including a plurality of first lens elements. The first lens array satisfies D.sub.1≦0.25.Math.P.sub.1 where P.sub.1 is a pitch in a first direction between optical axes of adjacent ones of the first lens elements, and D.sub.1 is a displacement amount that is an absolute value of a difference between a first length W.sub.E1 from a center position of the first lens array to an end position of the first lens array in the first direction at a first temperature, and a second length W.sub.E2 from the center position of the first lens array to the end position of the first lens array at a second temperature higher than the first temperature by 30° C.

Provided is a fixing device. The fixing device includes: a fixing belt including a base; a nip forming member arranged inside the fixing belt; and a pressing member arranged outside the fixing belt to face the nip forming member to form a fixing nip. The hardness of the nip forming member is configured with respect to the hardness of the base.

An image forming apparatus includes a housing and a drum unit. The drum unit is out of the housing at a first position, moved in a first direction from the first position to a second position in the housing, and then to a third position away from the first position. The drum unit includes: a photosensitive drum; a cleaning unit for toner; a conveying tube extending in the first direction; a conveying member in the conveying tube and rotatable about a first axis extending in the first direction; and a first gear fixed to the conveying member and rotatable about the first axis. The housing has a second gear rotatable about a second axis extending in the first direction. The first gear is separated from the second gear at the second position, and engaged with the second gear at the third position. The first axis and the second axis overlap in the third position.

An image forming apparatus includes a formation target that is wound around rotating bodies including a driving roller and transported by the rotating bodies including the driving roller while forming a shape having linear portions each of which forms a different angle, which is an acute angle or an angle of zero degrees, with a horizontal direction when viewed in an axial direction of the driving roller, first image forming bodies that are arranged along one of the linear portions in such a manner as to be spaced apart from each other by a first distance and that form images onto the formation target, and second image forming bodies that are arranged along another one of the linear portions, the other linear portion forming the angle larger than the angle formed by the one linear portion, in such a manner as to be spaced apart from each other by a second distance shorter than the first distance and that form images onto the formation target.