The invention is to provide an image forming apparatus and an electrophotographic cartridge, which are free from problems of cleaning failure, filming, soiling, residual images (ghosts), fogging, density reduction, noise and the like and which can provide high-definition images even when a toner having a small particle size and having a high degree of circularity is used and even when a photoreceptor having a small outer diameter is used. An image forming apparatus comprising: an electrophotographic photoreceptor containing a conductive support and a photosensitive layer on the conductive support, a charging unit for charging the electrophotographic photoreceptor, an imagewise exposing unit for imagewise exposing the charged electrophotographic photoreceptor to form an electrostatic latent image thereon, a developing unit for developing the electrostatic latent image with a toner, and a transferring unit for transferring the toner from the electrophotographic photoreceptor to a receiving unit, wherein the outer diameter of the electrophotographic photoreceptor is 20 mm or less, the photosensitive layer contains a polyarylate resin, and the toner satisfies the specific requirements (1) and (2).

An electrophotographic photoreceptor is provided that can achieve reductions in the amount of wear in the photoreceptor surface while producing an excellent image on a long-term basis. Also provided are a method of producing the electrophotographic photoreceptor and an electrophotographic apparatus. The electrophotographic photoreceptor includes a conductive substrate; and a photosensitive layer provided on the conductive substrate and being composed of a resin having a molecular structure optimized using molecular dynamic calculations that is a helical structure, and having a value for a ratio r/I between the diameter (r) and helix pitch (I) of the helical structure that ranges from 0.04 to 1.0.

A triarylamine derivative represented by general formula (1) below. In the general formula (1), R.sub.1, R.sub.2, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, and R.sub.9 each represent, independently from one another, a hydrogen atom, an optionally substitute alkyl group having a carbon number of at least 1 and no greater than 6, an optionally substituted alkoxy group having a carbon number of at least 1 and no greater than 6, or an optionally substituted aryl group having a carbon number of at least 6 and no greater than 14, R.sub.3 represents an alkyl group having a carbon number of at least 1 and no greater than 4, X represents an alkylene group having a carbon number of at least 1 and no greater than 6 or an oxygen atom, and n represents an integer of 1 to 3.

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An electrophotographic photosensitive member that abuts with a charging member and/or a developer carrying member with an abutting member interposed therebetween, wherein the electrophotographic photosensitive member has a first portion and a second portion abutting with the abutting member along the longitudinal direction thereof, the electrophotographic photosensitive member has a support, a charge generation layer containing a charge generating material and a polyacetal resin, and a surface layer in this order, the electrophotographic photosensitive member has, in the first portion, an undercoat layer containing a polymerized product of a composition including an electron transporting material and a cross-linking agent, the layer being adjacent to a surface of the charge generation layer, facing the support, and the electrophotographic photosensitive member has, in the second portion, an intermediate layer containing a metal oxide particle and a phenol resin, the layer being between and adjacent to the support and the charge generation layer.

Provided are an electrophotographic photoconductor that is less likely to cause transfer ghosting even when mounted in an electrophotographic apparatus with high transfer voltage set for high-speed or cleanerless processes, as well as a method of manufacturing the electrophotographic photoconductor, and an electrophotographic apparatus. The electrophotographic photoconductor includes a conductive substrate; an undercoat layer provided on the conductive substrate, and a photosensitive layer provided on the undercoat layer. In the electrophotographic photoconductor, the undercoat layer contains a resin binder and a first filler; and the first filler contains zinc oxide particles that are surface-treated with an N-acylated amino acid or an N-acylated amino acid salt.

Provided is an electrophotographic apparatus having high positive chargeability even in an electrophotographic apparatus that simultaneously uses toner containing alumina particles as an external additive and a photosensitive member containing a polyarylate resin excellent in mechanical strength. In the electrophotographic apparatus, the electrophotographic photosensitive member includes a monolayer type photosensitive layer containing a charge generating material, a hole transporting material, an electron transporting material, and a binder resin, the photosensitive layer contains a polyarylate resin having a structural unit represented by the formula (1) and a structural unit represented by the formula (2) as the binder resin, the toner is toner containing toner particles, the toner particles each contain a toner base particle and an external additive adhering to a surface of the toner base particle, and the external additive contains at least aluminum oxide particles.

A polyarylate resin includes repeating units represented by formulas (1), (2), (3), and (4). ##STR00001##
A third percentage is greater than 0% and less than 50%. The third percentage is a percentage of the number of repeats of the repeating unit represented by formula (3) relative to the total of the number of repeats of the repeating unit represented by formula (1) and the number of repeats of the repeating unit represented by formula (3). A fourth percentage is at least 35% and less than 70%. The fourth percentage is a percentage of the number of repeats of the repeating unit represented by formula (4) relative to the total of the number of repeats of the repeating unit represented by formula (2) and the number of repeats of the repeating unit represented by formula (4).

A single-layer photosensitive layer included in an electrophotographic photosensitive member contains a charge generating material, a hole transport material, an electron transport material, and a binder resin. The binder resin includes a polyarylate resin. The polyarylate resin includes repeating units represented by formulas (1), (2), (3), and (4). ##STR00001## The percentage of the number of repeats of the repeating unit represented by formula (3) relative to a total of the number of repeats of the repeating unit represented by formula (1) and the number of repeats of the repeating unit represented by formula (3) is greater than 0% and less than 20%.