An electrophotographic photosensitive member includes a photosensitive layer of a single layer. The photosensitive layer contains a charge generating material, a hole transport material, an electron transport material, and a binder resin. An optical response time is 0.05 milliseconds or longer and 0.85 milliseconds or shorter. The optical response time is a time from irradiation of a surface of the photosensitive layer charged to +800 V with pulse light having a wavelength of 780 nm to decay of a surface potential of the photosensitive layer from +800 V to +400 V. The pulse light has an intensity that allows the surface potential of the photosensitive layer to decay to +200 V from +800 V after 400 milliseconds elapse from the irradiation of the surface of the photosensitive layer charged to +800 V with the pulse light. The photosensitive layer has a Martens hardness at 50 C. of at least 160 N/mm.sup.2.

In an image forming apparatus, a cleaning member is pressed against a circumferential surface of an image bearing member and collects a toner remaining on the circumferential surface of the image bearing member. The toner has a number average roundness of 0.965 to 0.998. The toner has a D.sub.50 of 4.0 m to 7.0 m. A linear pressure of the cleaning member on the circumferential surface of the image bearing member is 10 N/m to 40 N/m. The image bearing member includes a single-layer photosensitive layer containing a charge generating material and a hole transport material. Ionization potential Ip.sub.HTM of the hole transport material and ionization potential Ip.sub.CGM of the charge generating material satisfy mathematical formula (1) Ip.sub.HTM5.30 eV, mathematical formula (2) Ip.sub.CGM5.30 eV, and mathematical formula (3) 0.09 eV|Ip.sub.HTMIp.sub.CGM|0.30 eV.

An electrophotographic photoreceptor includes a conductive substrate, and a lamination type photosensitive layer including a charge generation layer and a charge transport layer or a single layer type photosensitive layer that is a photosensitive layer disposed on the conductive substrate, in which the charge transport layer or the single layer type photosensitive layer is an outermost layer and contains a charge transport material, a polyester resin having a dicarboxylic acid unit (A) represented by Formula (A), and a compound that has a molecular weight of 255 or greater, has a phenol skeleton in which a primary carbon atom or a secondary carbon atom is bonded to one ortho position and a tertiary carbon atom or a quaternary carbon atom is bonded to the other ortho position, and has no linear alkylene structure having 4 or more carbon atoms.

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In Formula (A), Ar.sup.A1 and Ar.sup.A2 each independently represent an aromatic ring that may have a substituent, L.sup.A represents a single bond or a divalent linking group, and n.sup.A1 represents 0, 1, or 2.

The object of the present invention is to provide a positive charging electrophotographic photoreceptor having high sensitivity, low residual potential, and excellent chargeability, and relates to a positive charging electrophotographic photoreceptor including a conductive support, a photosensitive layer, and a protective layer in this order, the photosensitive layer containing a charge generation substance, a positive hole transport substance, and an electron transport substance in the same layer, in which the positive hole transport substance includes at least one of the compounds represented by any one of the following formulas (1) to (5), and a binder resin of the protective layer is an alcohol-soluble thermoplastic resin, providing that the symbols in the formula are defined in the specification.

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A contact charging type image forming apparatus, to which only a direct current voltage is applied, includes an electrophotographic photoreceptor that includes a conductive base material A and a photosensitive layer provided on the conductive base material A, and a charging member that includes a conductive base material B and an elastic layer provided on the conductive base material B, in which in a case where a dielectric film thickness of the electrophotographic photoreceptor is defined as L, and a resistance component of an impedance of the charging member in a range of 1 Hz or greater and 500 Hz or less, which is measured by an alternating current impedance method, is defined as R, Expression (1) is satisfied.

L<0.75log.sub.e(R)+15.79Expression (1)

An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer having a single-layer structure. The photosensitive layer contains a charge generating material, an electron transport material, a polycarbonate resin, and a hole transport material. The electron transport material includes a compound having a halogen atom and represented by general formula (1), (2), (3), (4), or (5). The hole transport material includes a compound represented by general formula (20), (21), (22), (23), (24), (25), (26), or (27). A charge of calcium carbonate as measured by charging the calcium carbonate through friction with the photosensitive layer is at least +6.5 C/g. A Vickers hardness of the photosensitive layer at 45 C. is at least 17.0 HV. ##STR00001## ##STR00002## ##STR00003##

A method for producing an electrophotographic photosensitive member includes an electrically conductive substrate and a photosensitive layer. The method includes applying an application liquid for photosensitive layer formation containing a solvent, a binder resin, and a hole transport material directly or indirectly onto the electrically conductive substrate, and removing a portion of the solvent, to form the photosensitive layer. The solvent contains a first solvent that is an alcohol having a carbon number of at least 1 and no greater than 3, and a second solvent other than the first solvent. The binder resin includes a polyarylate resin that is a polymerization product of monomers including a first monomer represented by general formula (1) and a second monomer represented by general formula (2),

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An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single-layer photosensitive layer and contains a charge generating material, a hole transport material, an electron transport material, and a binder resin. The binder resin has a viscosity average molecular weight of at least 25,000 and no greater than 50,000. A strain at break of the photosensitive layer is at least 4.9% and no greater than 13.0%. A scratch resistant depth of the photosensitive layer is no greater than 0.50 m.

An electrophotographic photosensitive member with suppressed potential variation even in the case that a protective layer including a cured material of a composition having a polymerizable functional group is used is provided. An electrophotographic photosensitive member including a support, a charge generation layer, a charge transport layer containing a charge transporting material, and a protective layer, in the order presented, wherein the charge transport layer contains a polycarbonate resin having a structure selected from a group A and a structure selected from a group B, and the protective layer includes a cured material of a composition containing a compound having at least a functional group selected from chain-polymerizable functional groups and sequential polymerizable functional groups.

An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer includes a charge generating layer and a charge transport layer. The charge generating layer contains a charge generating material. The charge transport layer contains a hole transport material and a binder resin. The charge transport layer further contains an electron acceptor compound. The hole transport material includes a compound represented by general formula (1). In general formula (1), R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.10 each represent, independently of one another, a hydrogen atom or a methyl group. ##STR00001##