Abstract: An electrophotographic photoreceptor includes a support, an undercoat layer placed on the support, a charge generation layer placed on the undercoat layer, and a charge transport layer placed on the charge generation layer. The undercoat layer contains titanium oxide particles surface-treated with an organosilicon compound that is at least one member selected from the group consisting of compounds represented by formulas (1) to (8) and a polyamide resin. The charge generation layer contains hydroxygallium phthalocyanine.

Abstract: The process cartridge includes an electrophotographic photosensitive member having a first support and a photosensitive layer; and a charging member. In the photosensitive member when an electric current is measured which flows when a voltage is applied to a surface while being varied, a gradient a1 of a low electric field region and a gradient a2 of a high electric field region satisfy a2/a1?1.50, in a graph. The charging member includes a second support having an electroconductive outer surface, and a second electroconductive layer including a matrix and a plurality of domains being dispersed in the matrix, at least a portion of the domain is exposed to an outer surface which includes at least the matrix and at least a portion of the domain, and a volume resistivity ?M of the matrix is 1.00×105 times or higher of a volume resistivity ?D of the domain.

Abstract: There is provided a process cartridge detachably attachable to a main body of an electrophotographic apparatus, the process cartridge including: an electrophotographic photosensitive member and a charging member, in which when average local potential differences of calculated lengths in the electrophotographic photosensitive member is calculated based on a specific method, a maximum value of the average local potential difference is 2 V or more, the charging member includes a support and an electro-conductive layer, the electro-conductive layer has a matrix and domains dispersed in the matrix, a volume resistivity ?M of the matrix is at least 1.00×105 times a volume resistivity ?D of the domain, and a specific calculated length SCP [?m] and a specific value relating a distance between the domains Dms [?m] satisfy SCP?3×Dms.

Abstract: Provided is a process cartridge in which lateral running is suppressed while satisfactory potential fluctuation is maintained. The process cartridge includes: an electrophotographic photosensitive member including a support, a lowermost layer, and a photosensitive layer; and a charging member including a support and a conductive layer. In a case where a maximum frequency at which a phase of an impedance reaches 45°, when the impedance is measured by applying an AC voltage to the lowermost layer while changing the AC voltage, is represented by fOPC (Hz), and in a case where a maximum frequency at which a phase of an impedance reaches 45°, when the impedance is measured by applying an AC voltage to the charging member while changing the AC voltage, is represented by fC (Hz), the fOPC and the fC each have a value within a certain range.

Abstract: The present disclosure provides an electrophotographic photosensitive member that reduces the accumulation of charge and the leakage which are caused by a repeated use in a long period of time. The electrophotographic photosensitive member has a support, an undercoat layer, a charge generation layer and a charge transport layer in this order, wherein the undercoat layer contains a polyamide resin, and a titanium oxide particle, wherein the titanium oxide particle has been surfacetreated with an organosilicon compound, wherein the undercoat layer satisfies 10???70, where ? represents a degree [%] of hydrophobicity of the titanium oxide particle which has been surfacetreated with the organosilicon compound; and the undercoat layer satisfies 0.015?(?×?)?0.040, where ? represents an average primary particle size [?m] of the titanium oxide particles, and ? represents a weight percentage [wt %] of an Si element of the organosilicon compound with respect to the titanium oxide particle.

Abstract: The electrophotographic photosensitive member has: a cylindrical support; a charge generating layer formed on the cylindrical support; and a charge transport layer formed on the charge generating layer, the charge generating layer contains a hydroxygallium phthalocyanine crystal having a particular CuK? characteristic X-ray diffraction peak, a titanyl phthalocyanine crystal having a particular CuK? characteristic X-ray diffraction peak or a chlorogallium phthalocyanine crystal having a particular spectral absorption spectrum as a charge generating material, and in the charge generating layer, with respect to the film thickness of the charge generating layer, when a region from the central position of an image forming area to the end position of the image forming area is divided in the axial direction of the cylindrical support into five equal regions and the average film thickness of the charge generating layer in each region satisfies a specific condition.

Abstract: Provided is an electrophotographic photosensitive member which enables a reduction in unevenness in distribution of the post-exposure potential of the photosensitive member and a reduction in unevenness in life of the photosensitive member in the axial direction. An electrophotographic photosensitive member, including a cylindrical support, a charge generating layer, and a charge transport layer in this order, wherein when a region from a central position of an image formation region of the electrophotographic photosensitive member to an end position of the image formation region in the axial direction of the cylindrical support is equally divided into five regions, average film thicknesses of the charge generating layer in the five regions satisfy specific relations in a film thickness of the charge generating layer and average film thicknesses of the charge transport layer in the five regions satisfy specific relations in a film thickness of the charge transport layer.

Abstract: Provided is an electrophotographic photosensitive member in which discharge streaks generated in an end portion can be suppressed. The electrophotographic photosensitive member includes a cylindrical support, a charge-generating layer, and a charge-transporting layer in the stated order. In the electrophotographic photosensitive member, when a region between a center position and a 90% position situated at a 90% of a length of from the center position to one end of the electrophotographic photosensitive member in an axial direction thereof from the center position, is defined as a region X, and a region between the 90% position and the end of the electrophotographic photosensitive member is defined as a region Z. Average thicknesses in regions obtained by equally dividing the region X into five and regions obtained by equally dividing the region Z into three satisfy particular relationships.

Abstract: An electrophotographic photosensitive member, including a cylindrical support, a charge generating layer formed on the cylindrical support, and a charge transport layer formed on the charge generating layer, in which in the charge generating layer, when a region from a central position of an image forming region to an end position of the image forming region in an axis direction of the cylindrical support is divided equally into five regions, film thicknesses of the charge generating layers in each of the regions satisfy a specific relationship with each other, and in the charge transport layer, when a region from the central position of the image forming region to the end position of the image forming region in the axis direction of the cylindrical support is divided equally into five regions, film thicknesses of the charge transport layers in each of the regions satisfy a specific relationship with each other.

Abstract: The present disclosure provides an electrophotographic photosensitive member that can simultaneously achieve the suppression of the occurrence of the black spot in a charged portion and the suppression of the deterioration in sensitivity of an exposed portion, even after stored in a high-temperature and high-humidity environment. An electrophotographic photosensitive member includes an electro-conductive support, an undercoat layer, a charge generation layer and a charge transport layer in this order, wherein an atomic concentration ratio R of the oxygen atom to the aluminum atom on the surface of the electro-conductive support, as measured by energy dispersive X-ray spectroscopy, satisfies the following Expression (1): 1.6?R??(1) and the undercoat layer includes a titanium oxide particle that is surface-treated with a particular silane compound.

Abstract: Provided is an electrophotographic photosensitive member that is improved in potential stability in long-term use under a high-temperature and high-humidity environment, and does not cause degradation in image quality, such as a low density. The electrophotographic photosensitive member includes: a support; an undercoat layer formed on the support; a charge-generating layer formed directly on the undercoat layer; and a charge-transporting layer formed on the charge-generating layer. The undercoat layer contains a polyamide resin, titanium oxide particles surface-treated with an organic silicon compound, and a compound represented by the following Formula (1), and has a content of the compound represented by the Formula (1) of 4 ppm or more and 80 ppm or less: in the Formula (1), R and R? each independently represent a methyl group or an ethyl group.

Abstract: An electrophotographic photoreceptor includes a support, an undercoat layer placed on the support, a charge generation layer placed on the undercoat layer, and a charge transport layer placed on the charge generation layer. The undercoat layer contains titanium oxide particles surface-treated with an organosilicon compound that is at least one member selected from the group consisting of compounds represented by formulas (1) to (8) and a polyamide resin. The charge generation layer contains hydroxygallium phthalocyanine.

Abstract: Provided is an electrophotographic photosensitive member that is improved in potential stability in long-term use under a high-temperature and high-humidity environment, and does not cause degradation in image quality, such as a low density. The electrophotographic photosensitive member includes: a support; an undercoat layer formed on the support; a charge-generating layer formed directly on the undercoat layer; and a charge-transporting layer formed on the charge-generating layer. The undercoat layer contains a polyamide resin, titanium oxide particles surface-treated with an organic silicon compound, and a compound represented by the following Formula (1), and has a content of the compound represented by the Formula (1) of 4 ppm or more and 80 ppm or less: in the Formula (1), R and R? each independently represent a methyl group or an ethyl group.

Abstract: The present disclosure provides an electrophotographic photosensitive member that reduces the accumulation of charge and the leakage which are caused by a repeated use in a long period of time. The electrophotographic photosensitive member has a support, an undercoat layer, a charge generation layer and a charge transport layer in this order, wherein the undercoat layer contains a polyamide resin, and a titanium oxide particle, wherein the titanium oxide particle has been surfacetreated with an organosilicon compound, wherein the undercoat layer satisfies 10???70, where ? represents a degree [%] of hydrophobicity of the titanium oxide particle which has been surfacetreated with the organosilicon compound; and the undercoat layer satisfies 0.015?(?×?)?0.040, where ? represents an average primary particle size [?m] of the titanium oxide particles, and ? represents a weight percentage [wt %] of an Si element of the organosilicon compound with respect to the titanium oxide particle.