An image forming unit includes a photoreceptor and a charging member that comes into contact with a surface of the photoreceptor and charges the photoreceptor, in which the photoreceptor includes a conductive substrate, and a lamination type photosensitive layer disposed on the conductive substrate and including a charge generation layer and a charge transport layer, the charge transport layer contains at least one of a polyester resin that has a constitutional unit having an aromatic ring or a polycarbonate resin that has a constitutional unit having an aromatic ring, the charging member includes a support member and an elastic layer disposed on the support member, and the elastic layer has a storage elastic modulus G′ of 5.0 MPa or less at a frequency of 100 Hz in dynamic viscoelasticity measurement under a temperature condition of 24° C.

An electrophotographic photosensitive member includes a conductive support having a thickness of 3 mm or more, a photosensitive layer disposed on the conductive support, and a surface protection layer disposed on the photosensitive layer, in which the surface protection layer is a layer composed of a film formed by curing a composition including a reactive group-containing charge transporting material including a reactive group and a charge transporting skeleton in the same molecule, or a film formed by curing a composition including an unreactive charge transporting material and a reactive group-containing non-charge transporting material that does not include a charge transporting skeleton and includes a reactive group, and the ratio of the degree of cure of the conductive support-side surface of the surface protection layer which faces the conductive support to the degree of cure of the outer periphery-side surface of the surface protection layer which serves as the outer periphery is 75% or more.

A fluorine-containing resin particle contains 0 or more and 30 or less carboxyl groups per 10.sup.6 carbon atoms and 0 ppm or more and 3 ppm or less of a basic compound.

A printing drum mounting system and method of assembling the mounting system. The mounting system comprising a rotatable shaft; a first mount and a second mount arrangeable on the shaft to clamp a printing drum therebetween, wherein the first mount comprises a first engaging surface to form a mating contact with a corresponding first end surface of the printing drum and the second mount comprises a second engaging surface to form a mating contact with a corresponding end surface of the printing drum; a double-walled flexure to flexibly mount the first engaging surface and the shaft, the flexure to provide the first engaging surface with a single degree of freedom of axial movement relative to the shaft and to maintain mating contact between the first engaging surface and the first end surface of the printing drum as the printing drum thermally expands and contracts; and a releasable fixing to align and rigidly engage the second engaging surface relative to the shaft.

An electrophotographic apparatus comprising an electrophotographic photosensitive member, a charging unit, and a developing unit, wherein the charging unit has a conductive member contactable with the electrophotographic photosensitive member, and a conductive layer of the conductive member has a matrix-domain structure; at least some of the domains are exposed at the outer surface; a volume resistivity R1 of the matrix and a volume resistivity R2 of the domains satisfy specific relationship; Martens hardness G1 of the matrix and Martens hardness G2 of the domains satisfy relationship G1<G2; the surface roughness Ra of the conductive member is not more than 2.00 μm; the toner has an external additive having a shape factor SF-1 of not more than 115; and A<Dms is satisfied where A is the number-average diameter of the external additive and Dms is a distance between adjacent walls between the domains.

A base material for an electrophotographic photoreceptor, in which in a spectrum of a period and an amplitude obtained by performing fast Fourier transform of surface roughness of a 10 mm portion in an axial direction of a surface of the base material for an electrophotographic photoreceptor, an amplitude in a range of a period of 0.4 mm or more and 0.7 mm or less is 0.22 mm or less.

The present invention relates to an electrophotographic photoreceptor including a conductive support and a photosensitive layer on the conductive support, and the photosensitive layer contains a polymer A containing a repeating structural unit represented by a specific formula, and a polymer B containing a repeating structural unit represented by a specific formula. In addition, the present invention relates to an electrophotographic photoreceptor cartridge and an image forming apparatus including the electrophotographic photoreceptor.

An image carrying member unit includes an image carrying member, a flange member, a shaft member, and a grounding member. The grounding member has a first bottom plate portion electrically connecting to the shaft member, and a pair of flat spring portions. Each flat spring portion has a first spring segment and a second spring segment bent from the tip end of the first spring segment via a second bent portion outward in the radial direction of the image carrying member to extend to approach the first bottom plate portion. Before insertion in the image carrying member, the distance between the second bent portions of the flat springs is smaller than the inner diameter of the image carrying member and the distance between tip end parts of the second spring segments is larger than the inner diameter of the image carrying member.

The present invention provides an electrophotographic photoreceptor including at least a laminated photoreceptive layer in which a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance are laminated in this order on a substrate, where the charge generating substance is a titanyl phthalocyanine showing diffraction peaks at least at Bragg angles (2θ±0.2°) 7.3°, 9.4°, 11.6°, 24.2° and 27.3° in an X-ray diffraction spectrum using CuKα ray, and the laminated photoreceptive layer includes an optical absorption spectrum that has a maximum absorption at 800 to 850 nm and where a ratio Abs.sub.860 nm/Abs.sub.780 nm of a peak intensity at 860 nm (Abs.sub.860 nm) to a peak intensity at 780 nm (Abs.sub.780 nm) is 0.6 or more to 1.2 or less when a minimum absorbance at 400 to 800 nm is calibrated to 0.

A photosensitive drum rotates about a first axis extending in a first direction. A photosensitive drum is located at one end portion of a housing in a second direction. A cleaning roller cleans a surface of the photosensitive drum. The cleaning roller rotates about a second axis extending in the first direction. A cleaning electrode is electrically connected to the cleaning roller. The cleaning electrode is located at an outer surface of the housing in the first direction. The cleaning electrode is located at a tip end of the one end portion of the housing in the second direction. The cleaning electrode includes a contact surface and a guide surface. The contact surface contacts an electrical contact to which a voltage is supplied. The contact surface is perpendicular to the first direction. The guide surface guides the electrical contact to the contact surface when the drum cartridge is mounted.