An image forming apparatus incudes a first conveyance guide portion having a first roller, a first engagement portion, and a second engagement portion, and includes a second conveyance guide portion having a second roller, a first engaged portion, and a second engaged portion. The first and second conveyance guide portions form a conveyance path where the first and second rollers convey a sheet. The second conveyance guide portion moves so that engagement between the second engagement portion and the second engaged portion is released and relative positioning between the second and first conveyance guide portions is released. When the first engagement portion and the first engaged portion engage each other and the relative positioning between the second and first conveyance guide portions is released, the second conveyance guide portion pivots in an opening direction relative to the first conveyance guide portion so that the conveyance path is opened.

A process unit includes a photoreceptor drum, a charging roller, and a cam member. The cam member includes a mounting portion that externally fits to a shaft portion of the charging roller and a contact portion that protrudes to an outside of the mounting portion. Then, the charging roller is maintained in a separate state by bringing the contact portion of the cam member into contact with an outer surface of the drum main body, and the charging roller is switched to a contact state by rotating the cam member dependently with rotation of the photoreceptor drum in a normal direction.

A developing cartridge includes: a casing; a developing roller rotatable about a developing axis extending in a first direction and positioned at one end portion of the casing in a second direction crossing the first direction; a developing electrode electrically connected to the developing roller and positioned at one end portion of the casing in the first direction; a supply roller rotatable about a supply axis extending in the first direction and configured to supply toner to the developing roller; a supply electrode electrically connected to the supply roller and positioned at one end portion of the casing in the first direction; and an IC chip having an electrical contact surface positioned at one end portion of the casing in the first direction. The electrical contact surface is positioned opposite the developing electrode in the second direction with respect to a part of the supply electrode.

An example charging member has a conductive support, a conductive elastic body layer on the conductive support, a first surface layer on the conductive elastic body layer, and a second surface layer on the first surface layer. The first surface layer includes a binder resin and a first plurality of first particles dispersed in the binder resin of the first surface layer, the second surface layer includes the binder resin, a second plurality of first particles, and second particles, the second plurality of first particles and the second particles being dispersed in the binder resin of the second surface layer, and an average diameter d.sub.1 of the first particles is 3 μm≤d.sub.1≤6 μm and an average diameter d.sub.2 of the second particles is 20 μm≤d.sub.2≤26 μm.

An image forming apparatus includes: an image carrier having a first rotation axle, a charging roller having a second rotation axle, a conductive member to contact a surface of the image carrier, a gap size acquisition device, and a gap adjustment device. The charging roller is disposed adjacent to the image carrier in a non-contact manner across a gap to charge the image carrier. The gap size acquisition device acquires a size of the gap. The gap adjustment device adjusts a distance between the first rotation axle and the second rotation axle based on information from the gap size acquisition device to maintain the size of the gap within a predetermined range.

A toner cartridge according to one example embodiment includes a developer roll and a toner adder roll. First and second drive gears are rotatably connected to and coaxial with the developer roll and toner adder roll, respectively. The toner cartridge includes a drive coupler exposed to receive rotational motion when the toner cartridge is installed in an image forming device. Gear teeth of the first drive gear are directly meshed with gear teeth of the drive coupler of the toner cartridge. The second drive gear is rotatably connected to the drive coupler through a pair of idler gears.

A processing device includes: a frame that supports a photosensitive drum; a bearing member that biases a charge roller in the direction to be in contact with the photosensitive drum; and a holder that is switchable between a holding state where the charge roller is separated from the photosensitive drum and a canceled state where the holding state is canceled so that the roller is brought into contact with the photosensitive drum; wherein a canceling member is provided in at least one of inside the processing-device attachment and an attachment body attached to an image forming apparatus main body at a front side to cause the holder to shift from the holding state to the canceled state. The canceling member causes the holder to shift from the holding state to the canceled state when the attachment body is attached to the image forming apparatus main body at the front side.

An electrophotographic apparatus comprising an electrophotographic photosensitive member, a charging device and a developing device, wherein the charging device comprises a conductive member arranged to be capable of contacting the electrophotographic photosensitive member, the conductive layer at the outer surface of the conductive member comprises a matrix and a plurality of domains dispersed in the matrix, at least some of the domains are exposed at the outer surface of the conductive member, the matrix has a volume resistivity R1 of larger than 1.0010.sup.12 .Math.cm, the volume resistivity R1 of the matrix is 1.010.sup.5 times or more a volume resistivity R2 of the domains, the developing device comprises the toner comprising a toner particle and a silica fine particle, and a coverage ratio of the toner surface with the silica fine particles is from 62.0% by area to 100.0% by area as determined by X-ray photoelectron spectroscopy.

A voltage generating apparatus includes: a first circuit configured to output a first voltage; a controller configured to control a value of the first voltage output by the first circuit with a control signal; and a storage unit configured to store control information of the first circuit. The controller uses the control signal for communication with the storage unit.

A drum cartridge includes a first photosensitive drum, a frame, a main body connector, a first toner cartridge connector, a drum-cartridge circuit board, a harness, and a first harness. The harness is electrically connected between the main body connector and the drum-cartridge circuit board. The harness extends in the first direction. The first harness is electrically connected between the first toner cartridge connector and the drum-cartridge circuit board. The first harness extends in the second direction.