Disclosed herein is a developing cartridge. The developing cartridge has a housing, a developing roller rotatably supported by the housing, the developing roller being rotatable about an axis extending in a first direction, and the developing roller having a developing roller shaft, a supply roller rotatably supported by the housing and configured to convey developer to the developing roller, the supply roller having a supply roller shaft, and a driving gear disposed on a driving side of the housing in the first direction. The developing cartridge also has electrical connection components on the housing. In the first direction, the ends of the supply roller shaft are in contact respectively with the electrical connection components.

An image forming apparatus includes an electrophotographic photoreceptor having a friction coefficient of a surface of 0.8 or less; a charging device including a charging member that is in contact with and charges the surface of the electrophotographic photoreceptor and includes a conductive base material, an elastic layer provided on the conductive base material and having a storage elastic modulus G of 5.0 MPa or less at 100 Hz, and a surface layer provided on the elastic layer; an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor to form a toner image by a developer containing a toner; and a transfer device that transfers the toner image to a surface of a recording medium.

A process cartridge is detachably mountable to a main assembly of an electrophotographic image forming apparatus. The cartridge includes an electrophotographic photosensitive drum, a developing roller, a drum unit containing the drum, a developing unit containing the roller and being movable so the roller contacts and is spaced from the drum, and a first force receiver receiving a force from a main-assembly first force applier by movement of a door from open to closed positions when mounting the cartridge and a second force receiver movable from a stand-by position by movement of the first force receiver by a force received from the first force applier. The second force receiver takes a projected position receiving a force from the second force applier to move the developing unit so the roller moves out of contact with the drum, the projected position being higher than the stand-by position.

An image forming apparatus includes an apparatus body including a main contact, and a main guide, and a cartridge including a memory contact, a moving unit moving into and out of the apparatus body in a first direction and including a frame to which the cartridge is attached, first and second protrusions protruding in a second direction orthogonal to the first direction from the end surface of the frame, an intermediate contact being in electrical contact with the memory contact, an unit contact being in electrical contact with the main contact, and a line conductor, the first protrusion being supported by the main guide of the apparatus body, the second protrusion being located above the first protrusion. At least part of the line conductor connecting the intermediate contact and the unit contact is located in a recess formed by the first protrusion, the second protrusion, and the end surface.

Provided is an electrophotographic photosensitive member including an electroconductive support, a photosensitive layer, and a protection layer, wherein the protection layer comprises an electroconductive particle, the electroconductive particle has a surface comprising a metal oxide containing a titanium atom and a niobium atom, an atomic concentration ratio of the niobium atom to the titanium atom in the metal oxide is 0.01 to 0.20, the electroconductive particle is surface-treated with a compound having a silicon atom, a content ratio of the electroconductive particle in the protection layer is 5 vol % or more and less than 40 vol % with respect to a total volume of the protection layer, and relative concentrations of a plurality of atoms at a surface of the protection layer, which are determined by X-ray photoelectron spectroscopy, satisfy specific conditions.

Provided are a process cartridge and an electrophotographic apparatus each capable of suppressing an image defect (coarseness in a halftone image) caused by toner scattering in association with a charging failure that occurs when the process speed of the electrophotographic apparatus is further increased. The process cartridge includes: an electrophotographic photosensitive member; and a developing unit, which includes a toner storing portion that stores a toner, and which supplies the toner to a surface of the electrophotographic photosensitive member. The electrophotographic photosensitive member includes a surface protective layer containing an electroconductive particle in an appropriate amount, and the volume resistivity of the surface protective layer is controlled. As the toner, there is used a toner in which an organosilicon polymer is present on the surface of a toner particle, a silanol group is present in part of the organosilicon polymer, and the amount of the silanol group is controlled.

A process cartridge that is detachable from a main body of an electrophotographic apparatus, in which a surface protective layer of an electrophotographic photosensitive member contains an electroconductive particle; the content of the electroconductive particle is 20.0 to 70.0% by volume of the surface protective layer; the surface protective layer has a volume resistivity of 1.0×10.sup.9 to 1.0×10.sup.14 Ω.Math.cm; a toner particle has at least one multivalent metal element selected from the group consisting of aluminum, magnesium, calcium, and iron; and a total content of the multivalent metal elements in the toner particle, as measured by coupled induction plasma atomic emission spectrometry (ICP-AES), is 0.10 to 1.25 μmol/g.

The electrophotographic apparatus and process cartridge comprising an electrophotographic photosensitive member, a cleaning blade, and developing unit containing a toner, wherein the cleaning blade comprising a support member and an elastic member whose portion is abutting a surface of the electrophotographic photosensitive member; the elastic member has an elastic modulus of 15 to 470 MPa with coefficient of variation for the elastic modulus being not more than 7.0%, and the absolute value of a difference between Martens hardness values is not more than 0.30 N/mm.sup.2 as measured under prescribed conditions; the toner contains a toner particle and an external additive whose a number-average primary particle diameter is from 5 to 25 nm, when X1 is a coverage ratio of the toner particle by the external additive and X2 is a theoretical coverage ratio, X1 is 50 to 85 area %, and X1/X2≥−0.0042×X1+0.60 is satisfied.

A process unit includes: a photosensitive drum on a surface of which a toner image is formed; a charging roller being pressed against the photosensitive drum so as to charge the photosensitive drum; a cleaning roller being pressed against the charging roller so as to clean the charging roller; and at least one biasing member biasing the charging roller or the cleaning roller. A central axis of the photosensitive drum is located at a position not overlapping with a central axis line passing through a central axis of the charging roller and a central axis of the cleaning roller. A biasing direction of the at least one biasing member is on a same line as the central axis line.

A developing cartridge includes: a casing, a developing roller, a first agitator, a supply roller, and a second agitator. The casing is configured to accommodate toner. The developing roller is rotatable about a developing roller rotation axis extending in a first direction. The first agitator is configured to agitate the toner. The first agitator is rotatable about a first agitator rotation axis extending in the first direction. The supply roller is positioned between the first agitator and the developing roller. The supply roller is rotatable about a supply roller rotation axis extending in the first direction. The second agitator is positioned between the supply roller and the first agitator. The second agitator is rotatable about a second agitator rotation axis extending in the first direction. A rotation locus of the second agitator is positioned outside of a rotation locus of the first agitator.