A drum unit includes: a frame; a first photosensitive drum; a second photosensitive drum; a charger; and a storage medium. The frame includes: a first frame plate; a second frame plate spaced apart from the first frame plate in a first direction; a third frame plate connecting one end of the first frame plate to one end of the second frame plate; and a fourth frame plate connecting another end of the first frame plate to another end of the second frame plate. The first photosensitive drum and the second photosensitive drum are rotatably supported by the frame. The second photosensitive drum is spaced apart from the first photosensitive drum and positioned closer to the third frame plate than the first photosensitive drum to the third frame plate in a second direction. The storage medium has an electrical contact surface positioned at an outer surface of the fourth frame plate.

A developing device configured to develop a latent image formed on a surface of an image bearer includes a rotator, a bearing, a holder, a first regulator, and a second regulator. The rotator includes a rotation shaft. The bearing supports the rotation shaft. The holder holds the bearing. The first regulator, disposed on any one of the bearing and the holder, regulates movement of the bearing such that the bearing does not fall toward one end side in an axial direction of the rotation shaft relative to the holder. The second regulator regulates movement of the bearing such that the bearing does not fall toward another end side in the axial direction relative to the holder after the bearing is attached to the holder.

An image forming apparatus includes a main body including a first guide portion and a second guide portion, a process cartridge including a photosensitive drum, a support frame configured to support the process cartridge and move between an inside position and an outside position. The support frame includes a first side frame. The first side frame includes a first guided portion to be guided by the first guide portion. The second side frame includes a second guided portion guided by the second guide portion A dimension of the first side frame is greater than or equal to a dimension of the first side frame. A dimension of the second side frame is greater than or equal to a dimension of the second side frame.

A developing cartridge includes a developing roller with a shaft, a housing with a wall portion, a developing electrode, a first contact portion, a second contact portion, and a connecting portion. The developing electrode includes a first contact portion contacting the shaft and has a first surface against which an apparatus electrode of an image forming apparatus body slides, a second contact portion disposed next to the first contact portion, and a second surface configured to contact an electrode of the image forming apparatus. The connecting portion includes a first inclined surface connecting the first surface and the second surface with each other and being contiguous with the first surface. The first inclined surface is inclined toward the second contact portion from the first contact portion such that the first inclined surface extends in a direction away from the wall portion.

An image forming apparatus includes a cartridge provided with a memory. The apparatus main body includes a frame, a movable electric contact unit including an electric contact portion contacting with the memory, and a holding member holding the electric contact portion and including an urging member urging the electric contact unit toward the memory in a mounted state of the cartridge, and a positioning portion positioning the electric contact unit in an unmounted state of the cartridge.

A replaceable unit for an electrophotographic image forming device includes a housing having a reservoir for holding toner. An electrical connector is positioned on a first side of the housing. The electrical connector includes an electrical contact for contacting a corresponding electrical contact in the image forming device and a magnetic sensor electrically connected to the electrical contact. The electrical connector is movable between a first position and a second position. When the electrical connector moves from the first position to the second position, the electrical contact of the replaceable unit moves from a retracted position to an operative position. When the electrical connector moves from the first position to the second position, the magnetic sensor moves from a misaligned position to an aligned position with a point in a path of movement of a magnet for sensing a magnetic field of the magnet.

A drum unit includes: a frame; a first photosensitive drum; a second photosensitive drum; a charger; and a storage medium. The frame includes: a first frame plate; a second frame plate spaced apart from the first frame plate in a first direction; a third frame plate connecting one end of the first frame plate to one end of the second frame plate; and a fourth frame plate connecting another end of the first frame plate to another end of the second frame plate. The first photosensitive drum and the second photosensitive drum are rotatably supported by the frame. The second photosensitive drum is spaced apart from the first photosensitive drum and positioned closer to the third frame plate than the first photosensitive drum to the third frame plate in a second direction. The storage medium has an electrical contact surface positioned at an outer surface of the third frame plate.

A replaceable unit for an electrophotographic image forming device according to one example embodiment includes an electrical contact positioned on a first side of a housing of the replaceable unit for contacting an electrical contact in the image forming device. A guide on the first side of the housing is positioned closer to a front of the housing than the electrical contact and leads rearward toward the electrical contact. The guide includes an inside surface that faces inward sideways toward a second side of the housing. At least a portion of the inside surface is angled inward sideways from front to rear permitting contact between the inside surface and an electrical connector in the image forming device to draw the electrical connector in the image forming device inward sideways relative to the replaceable unit during insertion of the replaceable unit into the image forming device.

A toner cartridge includes a photoconductive drum and a boss that protrudes outward from a first longitudinal end of the toner cartridge at a rotational axis of the photoconductive drum. An outermost axial segment of the boss along the rotational axis includes a partial cylinder having a cross-sectional shape of a circular segment. An outer circumferential surface of the partial cylinder is convex to a bottom of the toner cartridge and forms a bottom contact surface of the boss that is unobstructed to contact and sit in a corresponding V-block in an image forming device when the toner cartridge is installed in the image forming device. The outermost axial segment of the boss includes clearance above a topmost portion of the partial cylinder and within the radius of the outer circumferential surface of the partial cylinder permitting the clearance to accommodate one or more features in the image forming device.

A memory holder cover holds a memory holder so as to be movable with respect to the memory holder cover. An electrical contact contacts an electrical contact surface of a memory from above in a state where a cartridge is located at an attached position at which the cartridge is attached to a main housing. The main housing includes a guide groove having upper and lower guide surfaces. The upper guide surface guides movement of a memory holder from above when the cartridge is attached and detached. The lower guide surface guides movement of the memory holder from below when the cartridge is attached and detached. In a state where the cartridge is located at the attached position, the electrical contact surface is parallel to at least part of the upper guide surface or at least part of the lower guide surface.