An electrophotographic photosensitive member includes: a support; an undercoat layer; a charge generation layer; and a charge transport layer, wherein the undercoat layer contains a polyamide resin and a titanium oxide fine particle, and on the surface of the undercoat layer, an arithmetic mean roughness Ra and an average length Rsm of a roughness curve element both according to JIS B0601:2001 satisfy Ra≤50 nm and 0.1≤Ra/Rsm≤0.5; and the charge generation layer contains a hydroxygallium phthalocyanine pigment, wherein the hydroxygallium phthalocyanine pigment includes crystal particles having a crystal form exhibiting peaks at 7.4°±0.3° and 28.2°±0.3° at Bragg angles 2θ in a spectrum of X-ray diffraction using a CuKα, ray; and in a size distribution of the crystal particles, which is measured using small-angle X-ray scattering, a peak exists in a range of 20 to 50 nm, and the peak has a half-value width of 50 nm or smaller.

Provided is an electrophotographic apparatus which uses a light emitting diode array as an exposure unit and exposes a photosensitive member to a quantity of light from the LED array whose average light quantity satisfies 0.8×Emin or more and 1.1×Emin or less on condition that a normalized radius of curvature R of a normalized graph derived from the E-V curve of the photosensitive member has a minimum value of 0.24 or less, and a light quantity at the minimum value of the normalized radius of curvature R is Emin [μJ/cm.sup.2]. This electrophotographic apparatus prevents both the occurrence of image unevenness due to light quantity variation among the elements of the LED array and the generation of ghost images due to a rest potential.

Provided are an electrophotographic photoconductor being resistant to abrasion even in long-term use, having highly sensitive electric characteristics, being capable of maintaining a high retention rate, and being capable of providing a stable image without filming, a method of manufacturing the same, and an electrophotographic device. The photoconductor includes an electroconductive substrate (1), a charge generation layer (3), and a charge transport layer (4); the charge transport layer contains a hole transport material, a resin binder, an electron transport material, and an inorganic oxide; the charge generation layer contains a charge generation material; the masses of the hole transport material, the resin binder, the electron transport material, and the inorganic oxide in the charge transport layer respectively denoted by a to d satisfy 1.5≤b/a≤5.7, 0.005≤c/a≤0.35, 0.05≤d/a≤0.70, a≥c+d, and c/d≥0.01; the hole transport material contains a compound expressed by formula (A-1); and the charge generation material contains titanyl phthalocyanine having an exothermic peak at 251±5° C., a half-value width of the exothermic peak equal to or less than 15° C., and a heating value equal to or greater than 1.0 mJ/mg when a temperature rise condition is 20° C./min in differential scanning calorimetry, and having an X-ray diffraction peak at 27.2±0.3°. ##STR00001##

Provided is an electrophotographic photosensitive member including a support, a photosensitive layer, and a surface layer, wherein the surface layer includes a cured product of a composition containing at least one selected from the group consisting of: a charge-transportable compound; and electroconductive particles, and an organic salt having a polymerizable functional group, and wherein the organic salt is formed of an organic cation and at least one anion selected from the group consisting of: an organic anion; and an inorganic anion.

This electrophotographic photoreceptor includes at least a laminated photoreceptive layer, in which a charge generating layer and a charge transporting layer are laminated in this order on a conductive base. The charge transporting layer contains at least a charge transporting substance, a binder resin, and silica particles, and contains 0.1 ppm or more and 20 ppm or less of Na element and/or 0.01 ppm or more and 10 ppm or less of K element.

Provided is an electrophotographic photosensitive member having a feature in that, in a graph that is obtained by a method of measuring an EV curve, and that has a horizontal axis representing I and a vertical axis representing V, when V at I=0.500 [μJ/cm.sup.2] is represented by V.sub.r [V], a maximum value of S [V.Math.μJ/cm.sup.2] represented by S=I.Math.(V−V.sub.r) in a range of I=0.000 to 0.030 [μJ/cm.sup.2] is represented by S.sub.max [V.Math.μJ/cm.sup.2], and a product of a light amount I.sub.i [μJ/cm.sup.2] on the horizontal axis and a potential V.sub.i[V] on the vertical axis at a point of intersection between an approximate straight line in a range of I=0.000 to 0.010 [μJ/cm.sup.2] and an approximate straight line in a range of I=0.490 to 0.500 [μJ/cm.sup.2] is represented by S.sub.i=I.sub.i.Math.(V.sub.i−V.sub.r) [V.Math.μJ/cm.sup.2], a ratio of S.sub.i to S.sub.max, which is represented by AR=S.sub.i/S.sub.max, satisfies AR≤0.10.

In a positively charging single layer type electrophotographic photoreceptor having an over coat layer, an electrophotographic photoreceptor that is excellent in mechanical strength, electric characteristics, and adhesiveness, an electrophotographic photoreceptor cartridge, and an image formation device are provided. In a positively charging electrophotographic photoreceptor having a single layer type photosensitive layer and an over coat layer, the Martens hardness on the photoreceptor surface satisfies the prescribed condition, and preferably the photosensitive layer satisfies the particular relational expression of the contents and the molecular weights of the hole transporting substance and the electron transporting substance contained therein, thereby solving the problem.

To provide an image formation device that is capable of printing without problems in chargeability, leak resistance, gas resistance, and abrasion resistance, even with a contact charging system, and an electrophotographic photoreceptor and an electrophotographic photoreceptor cartridge used in the image formation device. The problem can be solved by an image formation device of a contact charging system including a positively charging electrophotographic photoreceptor including a single layer photosensitive layer and an over coat layer containing a cured product formed by curing a curable compound.

An electrophotographic 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, in which the charge transport layer contains a polyester resin (1) having a dicarboxylic acid unit (A) represented by Formula (A) and a diol unit (B) represented by Formula (B), and a charge transport material, and in a case where a weight-average molecular weight Mw of the polyester resin (1) contained in the charge transport layer is defined as A (10,000), a value of a ratio M1/M2 of a mass M1 of the charge transport material contained in the charge transport layer to a mass M2 of the charge transport layer is defined as Cs, and an average thickness of the charge transport layer is defined as Ds (μm), expressions of 5≤A≤40, 0.28≤Cs≤0.55, 27≤Ds≤50, and 2.5≤(A×Ds)/(Cs×100)≤70.0 are satisfied.

##STR00001##

In Formula (A), n.sup.1 represents 1, 2, or 3, n.sup.1 number of m.sup.1's each independently represent 0, 1, 2, 3, or 4, m.sup.1 number of Ra.sup.1's each independently represent an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.

In Formula (B), Rb.sup.1 and Rb.sup.2 each independently represent a hydrogen atom, an alkyl group having 1 or more and 20 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an aralkyl group having 7 or more and 20 or less carbon atoms, Rb.sup.3, Rb.sup.4, Rb.sup.5, Rb.sup.6, Rb.sup.7, Rb.sup.8, Rb.sup.9, and Rb.sup.10 each independently represent a hydrogen atom, an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, an aralkyl group having 7 or more and 20 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, and Rb.sup.1 and Rb.sup.2 may be bonded to each other to form a cyclic alkyl group.

An electrophotographic photoreceptor comprising at least a photosensitive layer on a conductive substrate, wherein the photosensitive layer is a laminate having a charge transport layer and a charge generation layer, the charge transport layer contains four or more types of compounds each having a maximum absorption wavelength falling within a wavelength range of from 300 nm to 600 nm in a tetrahydrofuran solution at 25° C., and maximum absorption wavelengths falling within the wavelength range of at least four types of the compounds of said four or more types of the compounds are separated from each other by 10 nm or more.