An electrophotographic photosensitive member that has an electroconductive support and a photosensitive layer on the electroconductive support, and reduces image failures. The surface layer of the electrophotographic photosensitive member includes a cured product of a composition of: a charge transporting compound having a specific polymerizable functional group; a polytetrafluoroethylene particle having a specific primary particle diameter; and a polymer having specific structural units and having weight average molecular weight.

An electrophotographic photosensitive member that has an electroconductive support and a photosensitive layer on the electroconductive support, and reduces image failures. The surface layer of the electrophotographic photosensitive member includes a cured product of a composition of: a charge transporting compound having a specific polymerizable functional group; a polytetrafluoroethylene particle having a specific primary particle diameter; and a polymer having specific structural units and having weight average molecular weight.

A charging member includes a conductive base material; an elastic layer that is provided on the conductive base material and has a storage elastic modulus G of 5.0 MPa or less at 100 Hz; and a surface layer that is provided on the elastic layer, in which in a Cole-Cole plot obtained by measuring the charging member in a range of 1 MHz to 0.1 Hz by an alternating current impedance method, a resistance component Ra of a capacitive semicircle including 2.5 kHz is 6.3×104Ω or less.

A charging member includes a conductive base material; an elastic layer that is provided on the conductive base material and has a storage elastic modulus G of 5.0 MPa or less at 100 Hz; and a surface layer that is provided on the elastic layer, in which in a Cole-Cole plot obtained by measuring the charging member in a range of 1 MHz to 0.1 Hz by an alternating current impedance method, a resistance component Ra of a capacitive semicircle including 2.5 kHz is 6.3×104Ω or less.

An electrophotographic photoreceptor includes a conductive substrate, an undercoat layer on the conductive substrate, a charge generation layer on the undercoat layer, a charge transport layer on the charge generation layer, and an inorganic protection layer on the charge transport layer, in which the charge transport layer contains a binder resin and a charge transport material, and, when impedance of the charge transport layer is measured, a ratio (C.sub.1 Hz/C.sub.10 Hz) of an electrostatic capacitance C.sub.1 Hz at 1 Hz to an electrostatic capacitance C.sub.10 Hz at 10 Hz is 1.1 or less.

An electrophotographic photoreceptor includes a conductive substrate, an undercoat layer on the conductive substrate, a charge generation layer on the undercoat layer, a charge transport layer on the charge generation layer, and an inorganic protection layer on the charge transport layer, in which the charge transport layer contains a binder resin and a charge transport material, and, when impedance of the charge transport layer is measured, a ratio (C.sub.1 Hz/C.sub.10 Hz) of an electrostatic capacitance C.sub.1 Hz at 1 Hz to an electrostatic capacitance C.sub.10 Hz at 10 Hz is 1.1 or less.

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 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.

Provided is an electrophotographic photosensitive member including a support, a charge-generating layer, a first hole-transporting layer, and a second hole-transporting layer, wherein the second hole-transporting layer contains a hole-transportable compound represented by the formula (1) (mass: W1, energy value of the highest occupied molecular orbital: CTM1HOMO), and a hole-transportable compound represented by the formula (2) (mass: W2) and/or a hole-transportable compound represented by the formula (3) (mass: W3) (energy value of the highest occupied molecular orbital: CTM2HOMO), wherein a value calculated from the expression (I) is from 0.05% by mass to 5.0% by mass, and wherein the expression (II) is satisfied: (W2+W3)/(W1+W2+W3)×100 (% by mass)—Expression (I); and 0.05 (eV)≤|CTM2HOMO|-|CTM1HOMO|≤0.30 (eV)—(II).