An image forming apparatus includes: an image carrier unit that is attachable to and removable from an apparatus body and that includes an image carrier; a development roller that passes toner to the image carrier when located in a position near the image carrier; an operation portion that moves, when operated, between a block position in which the operation portion blocks detachment of the image carrier unit from the apparatus body and an allowance position in which the operation portion allows detachment of the image carrier unit from the apparatus body, the development roller moving toward the image carrier in association with a movement of the operation portion to the block position, and the development roller moving away from the image carrier in association with a movement of the operation portion to the allowance position; and a positioning portion that positions the image carrier unit relative to the apparatus body in an attachment-removal direction of the image carrier unit when the operation portion is moved to the block position.

An image forming apparatus includes a rotatable image bearing member about a rotational axis extending in the axial direction, a charging member, an accommodating portion accommodating toner charged to a predetermined polarity; a developing member, a transfer portion, a static eliminating portion, and a collecting member. In the axial direction, when A is a eliminating width with which the eliminating portion discharges the surface of the image bearing member, B is an effective charging width with which the charging member charges the surface, and C is a collection contacting width with which the collecting member contacts the surface, the formula A<B<C is satisfied. In the axial direction, a surface potential of the surface in an area outside the effective charging width, inside the collection contacting width and in contact with the collecting member is a first potential larger than 0V in the same polarity direction as the predetermined polarity.

The image forming apparatus includes an image carrier, a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning blade, and a controller. The controller detects printing-coverage rates on a basis of plural areas divided in the longitudinal direction of the image carrier. Upon occurrence of a difference exceeding a specified threshold value among the coverage rates of the plural areas, the controller executes, for a duration of specified aging time, aging process in which the image carrier is driven into rotation in its charged state.

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.

A toner set for electrostatic image development includes a cyan toner, a magenta toner, and a yellow toner, wherein the Vicat softening temperatures of the toners are respectively in the range of from about 30 C. to about 60 C., and among the toners, the difference between the Vicat softening temperature of the toner having the highest Vicat softening temperature and the Vicat softening temperature of the toner having the lowest Vicat softening temperature is from about 1 C. to about 5 C.

A roller member includes a core member; a substantially round-cylindrical elastic member through which the core member extends and having chamfered portions, the chamfered portions each provided at two respective ends of the elastic member and having a surface roughness of about 50 m or less; and a coating film provided over an outer peripheral surface of the elastic member and at least a part of each of the chamfered portions.

An image forming apparatus includes a photosensitive member, a charging member, a charging voltage applying portion, an exposure unit, a developing member, a developing voltage applying portion, a transfer member, a transfer voltage applying portion, and a controller. In a discharging operation, an exposure surface is formed on a photosensitive member surface by exposing the photosensitive member surface to light by the exposure unit. The controller carries out control so that: a developing voltage on a side of a predetermined polarity relative to an exposure surface potential is applied to the developing member; a transfer voltage less than a discharge start voltage in absolute value of a potential difference between itself and the exposure surface potential of the is applied to the transfer portion; and a charging voltage on the side of the predetermined polarity relative to the exposure surface potential is applied to the charging member.

A process cartridge includes: a drum cartridge; and a developing cartridge. The drum cartridge includes: a drum frame; a photosensitive drum rotatable about a first axis extending in a first direction; and a first memory having a first electrical contact surface. The developing cartridge is attachable to the drum frame and includes: a casing; a developing roller rotatable about a second axis extending in the first direction; a second memory having a second electrical contact surface; and a developing holder holding the second electrical contact surface such that the second electrical contact surface is movable relative to the casing. The drum cartridge further includes an elastic member that can expand and contract in a second direction crossing the first direction. The developing holder is connected to the elastic member and is movable in the second direction in a state where the developing cartridge is attached to the drum frame.

A drum unit including a photosensitive drum may satisfy an equation of V0.489Q0.014(%), where V={1(V1/V0)}100(%). V0 is a surface potential of the photosensitive drum that is measured under a first condition that exposes a surface of the photosensitive drum at an exposure amount Q in a range of 0.13 to 0.34 J/cm2 while the photosensitive drum is rotated at a circumferential speed of 151 mm/s with the surface of the photosensitive drum being charged with a voltage having 1000 volts and a first polarity. V1 is a surface potential of the photosensitive drum that is measured under the first condition again after the surface of the photosensitive drum is applied for 406 seconds with a voltage having 2850 volts and a second polarity while the photosensitive drum is rotated at the circumferential speed of 73 mm/s.

A roller member includes a core member; a substantially round-cylindrical elastic member through which the core member extends and having chamfered portions, the chamfered portions each provided at two respective ends of the elastic member and having a surface roughness of about 50 m or less; and a coating film provided over an outer peripheral surface of the elastic member and at least a part of each of the chamfered portions.