Abstract: A positively chargeable electrophotographic photoreceptor includes a single layer-type photosensitive layer that contains a hole transport material, an electron transport material, a charge generation material, and a binder resin, in which the binder resin contains a resin A having an elastic deformation rate of 53.0% or more and a resin B having an elastic deformation rate difference of 12% or more and 17% or less with respect to the resin A.

Abstract: An electrophotographic photoreceptor includes: a conductive substrate; and a photosensitive layer that is disposed on the conductive substrate and has a charge generation layer and a charge transport layer. The charge transport layer contains a charge-transporting material and a polyarylate resin having a dicarboxylic acid unit represented by formula (A) and a diol unit represented by formula (B). The mass ratio of the charge-transporting material in the charge transport layer is 56 mass % or more and 70 mass % or less. In formula (A), n1 is 1, 2, or 3, n1 m1's are each independently 0, 1, 2, 3, or 4, and m1 Ra1's are each independently a C1-C10 alkyl group, a C6-C12 aryl group, or a C1-C6 alkoxy group.

Abstract: A charging member includes a support member, an elastic layer provided on the support member, an outer layer provided on the elastic layer, and a protective layer provided as an outermost layer on the outer layer. The protective layer contains silica and has a silicon element concentration of 10 atomic % or more, and the outer peripheral surface has a contact angle with water of 35 degrees or less.

Abstract: A charging device includes: a charging member that rotates in contact with a charged body and charges the charged body; and a cleaning member that comes into contact with the charging member and rotates in conjunction with the charging member, in which the cleaning member includes a foam elastic layer in which a band-shaped foam elastic member is spirally disposed with a pitch, and a diameter of a tip end portion of a cell skeleton protruding to a surface of the foam elastic layer is 50 ?m or less, and a peripheral speed ratio of the cleaning member to the charging member is 0.3 or more and 0.7 or less.

Abstract: A charging member includes a support member, an elastic layer provided on the support member, an outer layer provided on the elastic layer, and a protective layer provided as an outermost layer on the outer layer. The protective layer contains silica and has a silicon element concentration of 10 atomic % or more, and the outer peripheral surface has a contact angle with water of 35 degrees or less.

Abstract: A charging device includes: a charging member that rotates in contact with a charged body and charges the charged body; and a cleaning member that comes into contact with the charging member and rotates in conjunction with the charging member, in which the cleaning member includes a foam elastic layer in which a band-shaped foam elastic member is spirally disposed with a pitch, and a diameter of a tip end portion of a cell skeleton protruding to a surface of the foam elastic layer is 50 ?m or less, and a peripheral speed ratio of the cleaning member to the charging member is 0.3 or more and 0.7 or less.

Abstract: A charging member includes: an electrically conductive base; an elastic layer disposed on the electrically conductive base; and a surface layer disposed on the elastic layer. A PFVTF value of a surface of the surface layer is 1.5 or less. The PFVTF value is obtained by Fourier transforming a roughness curve of the surface of the surface layer that is measured in a circumferential direction to thereby obtain amplitude intensities at different periods, multiplying the amplitude intensities at different periods by VTF coefficients at respective periods that are obtained from a visual characteristic VTFL* (f=period) for lightness L* represented by Formula (V) below to thereby obtain corrected amplitude intensities at different periods, and integrating the corrected amplitude intensities in a period range of from 100 ?m to 1000 ?m inclusive: VTFL*(f)=5.05×(e(?0.843×1×f)?e(?1.454×1×f)).

Abstract: A charging member includes: an electrically conductive base; an elastic layer disposed on the electrically conductive base; and a surface layer disposed on the elastic layer. A PFVTF value of a surface of the surface layer is 1.5 or less. The PFVTF value is obtained by Fourier transforming a roughness curve of the surface of the surface layer that is measured in a circumferential direction to thereby obtain amplitude intensities at different periods, multiplying the amplitude intensities at different periods by VTF coefficients at respective periods that are obtained from a visual characteristic VTFL* (f=period) for lightness L* represented by Formula (V) below to thereby obtain corrected amplitude intensities at different periods, and integrating the corrected amplitude intensities in a period range of from 100 ?m to 1000 ?m inclusive: VTFL*(f)=5.05×(e(?0.843×1×f)?e(?1.

Abstract: A cleaning body includes a core, and a foam elastic layer that is disposed by winding a strip-shaped foam elastic member around an outer peripheral surface of the core in a helical shape from one end to the other end of the core, in which the foam elastic layer has cells and a cell skeleton that is a partition wall present between the cells, the cell skeleton has a tip portion protruding on a contact surface of the foam elastic layer with a body to be cleaned, and a diameter of the tip portion is equal to or less than 50 ?m, and in the cells, a ratio Dy/Dx of an average cell diameter Dy in a radial direction of the core to an average cell diameter Dx in a width direction of the foam elastic layer is equal to or greater than 1.2 and equal to or less than 2.1.

Abstract: A conductive member includes a substrate, an elastic layer on the substrate, and a surface layer on the elastic layer. The surface layer contains a conductive agent and has a sea-island structure including a sea containing a first resin and islands containing a second resin. The area occupancy of the islands in a cross section of the surface layer is 10% or more and 50% or less.

Abstract: A charging member of a contact charging system that applies only a direct-current voltage to the charging member includes a conductive substrate, an elastic layer disposed on the conductive substrate, and a surface layer disposed on the elastic layer. When measured by an alternating-current impedance method within a range of 1 MHz to 1 mHz in an environment at a temperature of 28° C. and a humidity of 85%, a resistance component R of an impedance within a range of 1 Hz to 100 Hz is 4.0×104 ? or more and 1.0×106 ? or less and an impedance Z within a range of 1 Hz to 100 Hz is over 3.6×104 ? and 3.5×105 ? or less.

Abstract: A conductive member includes a substrate, an elastic layer on the substrate, and a surface layer on the elastic layer. The surface layer contains a conductive agent and has a sea-island structure including a sea containing a first resin and islands containing a second resin. The area occupancy of the islands in a cross section of the surface layer is 10% or more and 50% or less.

Abstract: A charging member of a contact charging system that applies only a direct-current voltage to the charging member includes a conductive substrate, an elastic layer disposed on the conductive substrate, and a surface layer disposed on the elastic layer. When measured by an alternating-current impedance method within a range of 1 MHz to 1 mHz in an environment at a temperature of 28° C. and a humidity of 85%, a resistance component R of an impedance within a range of 1 Hz to 100 Hz is 4.0×104? or more and 1.0×106? or less and an impedance Z within a range of 1 Hz to 100 Hz is over 3.6×104? and 3.5×105? or less.

Abstract: A cleaning body includes a core, a foam elastic layer that is disposed to be wound around an outer peripheral surface of the core in a helical shape from one end to the other end of the core, and an adhesive layer that adheres the core and the foam elastic layer, in which a diameter of a tip portion of a cell skeleton protruding on a surface of the foam elastic layer is equal to or less than 50 ?m, and in a case where an inner peripheral length of the foam elastic layer in a cross section of the core in a radial direction is X (mm) and a thickness of the foam elastic layer is Y (mm), a value of X×Y2 is equal to or greater than 45.

Abstract: A cleaning body includes a core and a foamed elastic layer spirally wound around an outer circumferential surface of the core from one end of the core to the other end. An end portion of a cell skeleton protruding from a surface of the foamed elastic layer has an equivalent circle diameter of 50 ?m or less. The foamed elastic layer has a spiral pitch R2 of 5 mm or less and a spiral angle ? of 15° or less.

Abstract: A charging device includes a charging roller and a cleaning roller that includes a core and a foamed elastic layer disposed on an outer circumferential surface of the core and that rotates in contact with a surface of the charging roller. The number of ends of a cell skeleton that protrude from a surface of the foamed elastic layer is 25 ends/mm2 or more and 50 ends/mm2 or less. The cleaning roller is disposed in contact with the charging roller such that the compression ratio of the foamed elastic layer is 30% or less. The compression ratio is represented by Equation (1): compression ratio (%)=(r1/2+r2/2?d)/t1×100??Equation (1): where r1 is the outer diameter (mm) of the cleaning roller, r2 is the outer diameter (mm) of the charging roller, d is the interaxial distance (mm) between the charging roller and the cleaning roller, and t1 is the thickness (mm) of the foamed elastic layer of the cleaning roller.

Abstract: A charging device includes: a charging member that charges an image holding member according to a contact charging method, and includes a conductive substrate and a surface layer provided on the conductive substrate; and a clean member that cleans the charging member while contacting the charging member, and includes a shaft and a foamed elastic layer provided on the shaft, wherein a ratio of a distance between irregularities in an axial direction of the surface layer in the charging member (Sm) to a width of a nodal section of a foam cell wall surface protruding from a surface of the foamed elastic layer in the clean member (W) satisfies 2.4?Sm/W?5.9.

Abstract: A charging device includes: a charging member that charges an image holding member according to a contact charging method, and includes a conductive substrate and a surface layer provided on the conductive substrate; and a clean member that cleans the charging member while contacting the charging member, and includes a shaft and a foamed elastic layer provided on the shaft, wherein a ratio of a distance between irregularities in an axial direction of the surface layer in the charging member (Sm) to a width of a nodal section of a foam cell wall surface protruding from a surface of the foamed elastic layer in the clean member (W) satisfies 2.4?Sm/W?5.9.

Abstract: A charging device includes a charging member that includes a conductive elastic layer and a conductive surface layer disposed on an outer circumferential surface of the conductive elastic layer and a cleaning member that includes a support and a foamed elastic layer disposed on an outer circumferential surface of the support and having a higher surface free energy than the conductive surface layer of the charging member and that rotates in contact with the conductive surface layer of the charging member.

Abstract: A cleaning member includes a shaft, and a foamed elastic layer that is disposed on an outer surface of the shaft and in which a relationship between a stress Pw generated by 70% compression deformation and a stress Ps generated by 10% compression deformation satisfies Pw/Ps?6.