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 height of convexities in a 0.7-mm-square area of a surface of the charging member is measured at five or more different positions in an axial direction and calculated. A height of a position where the charging member occupies 0.01 area % from a highest portion is defined as a reference height. An average proportion of areas occupied by the charging member at a position 1.7 ?m lower than the reference height is 2 area % or less relative to 100 area % of the 0.7-mm-square area.

Abstract: A height of convexities in a 0.7-mm-square area of a surface of the charging member is measured at five or more different positions in an axial direction and calculated. A height of a position where the charging member occupies 0.01 area % from a highest portion is defined as a reference height. An average proportion of areas occupied by the charging member at a position 1.7 ?m lower than the reference height is 2 area % or less relative to 100 area % of the 0.7-mm-square area.

Abstract: A gas control device includes a pump, a valve, a cuff, and a controller. The valve includes a first plate having a first vent hole and a first vent hole, a channel forming plate having an exhaust hole and an exhaust channel, a second plate having a second vent hole, and an edge separation plate. A manchette rubber tube in the cuff is joined to the periphery of the second vent hole in the second plate by an adhesive, and thus the valve is connected to the cuff. The exhaust hole is opened to the atmosphere. The pump includes a pump housing having a discharge hole and a discharge hole. The upper surface of the pump housing is joined to the bottom surface of the edge separation plate.

Abstract: An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer disposed on the conductive substrate, wherein when time that takes for a current value to reach the maximum after beginning of application of a square wave voltage to the electrophotographic photoreceptor is T1 and time that takes for the current value to reach the maximum after the beginning of the application of the square wave voltage and then decrease to one fifth of the maximum is T2, T2 is approximately from 3.2 to 11.0 times as large as T1.

Abstract: An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer disposed on the conductive substrate, wherein when time that takes for a current value to reach the maximum after beginning of application of a square wave voltage to the electrophotographic photoreceptor is T1 and time that takes for the current value to reach the maximum after the beginning of the application of the square wave voltage and then decrease to one fifth of the maximum is T2, T2 is approximately from 3.2 to 11.0 times as large as T1.

Abstract: A charging member includes a support, a conductive elastic layer disposed on the support, and a surface layer disposed on the conductive elastic layer. Domains with current values of 2.5 pA or more have an average size of about 300 nm or less in a binary image created using a current value of 2.5 pA as a threshold from current measured by contacting a conical probe having a tip diameter of 20 nm with an outer surface of the surface layer and applying a voltage of 3 V between the conical probe and the support while moving the conical probe.

Abstract: A charging member includes a support, a conductive elastic layer disposed on the support, and a surface layer disposed on the conductive elastic layer. Domains with current values of 2.5 pA or more have an average size of about 300 nm or less in a binary image created using a current value of 2.5 pA as a threshold from current measured by contacting a conical probe having a tip diameter of 20 nm with an outer surface of the surface layer and applying a voltage of 3 V between the conical probe and the support while moving the conical probe.

Abstract: A charging member includes a support member, a conductive elastic layer disposed on the support member, and a front surface layer disposed on the conductive elastic layer. Irregularities with a cycle of shorter than 0.1 mm and irregularities with a cycle of 0.1 mm or longer are distributed on an entirety of an outer circumferential surface of the charging member, and satisfy the following conditions of (1) and (2): (1) the irregularities with the cycle of shorter than 0.1 mm have an average height of greater than 0 ?m and 4 ?m or less; and (2) the irregularities with the cycle of 0.1 mm or longer have an average height of from 5 ?m to 30 ?m. A half-value width of a maximum frequency value of height distribution on the outer circumferential surface is from 1 ?m to 3 ?m.

Abstract: A charging member includes a support member, a conductive elastic layer disposed on the support member, and a front surface layer disposed on the conductive elastic layer. Irregularities with a cycle of shorter than 0.1 mm and irregularities with a cycle of 0.1 mm or longer are distributed on an entirety of an outer circumferential surface of the charging member, and satisfy the following conditions of (1) and (2): (1) the irregularities with the cycle of shorter than 0.1 mm have an average height of greater than 0 ?m and 4 ?m or less; and (2) the irregularities with the cycle of 0.1 mm or longer have an average height of from 5 ?m to 30 ?m. A half-value width of a maximum frequency value of height distribution on the outer circumferential surface is from 1 ?m to 3 ?m.

Abstract: A charging member includes a support member, a conductive elastic layer disposed on the support member, and a front surface layer disposed on the conductive elastic layer. Irregularities with a cycle of shorter than 0.1 mm and irregularities with a cycle of 0.1 mm or longer are distributed on an entirety of an outer circumferential surface of the charging member, and satisfy the following conditions of (1) and (2): (1) the irregularities with the cycle of shorter than 0.1 mm have an average height of from 8 ?m to 11 ?m; and (2) the irregularities with the cycle of 0.1 mm or longer have an average height of from 2 ?m to 5 ?m. A half-value width of the maximum frequency value of height distribution on the outer circumferential surface is from 1 ?m to 3 ?m.

Abstract: A charging member includes a support member, a conductive elastic layer disposed on the support member, and a front surface layer disposed on the conductive elastic layer. Irregularities with a cycle of shorter than 0.1 mm and irregularities with a cycle of 0.1 mm or longer are distributed on an entirety of an outer circumferential surface of the charging member, and satisfy the following conditions of (1) and (2): (1) the irregularities with the cycle of shorter than 0.1 mm have an average height of from 8 ?m to 11 ?m; and (2) the irregularities with the cycle of 0.1 mm or longer have an average height of from 2 ?m to 5 ?m. A half-value width of the maximum frequency value of height distribution on the outer circumferential surface is from 1 ?m to 3 ?m.

Abstract: A charging member includes a support member, a conductive elastic layer disposed on the support member, and a front surface layer disposed on the conductive elastic layer. Irregularities with a cycle of shorter than 0.1 mm and irregularities with a cycle of 0.1 mm or longer are distributed on an entirety of an outer circumferential surface of the charging member, and satisfy the following conditions of (1) and (2): (1) The irregularities with the cycle of shorter than 0.1 mm have an average height of 5 ?m to 8 ?m; and (2) The irregularities with the cycle of 0.1 mm or longer have an average height of 6 ?m to 30 ?m. A half-value width of a maximum frequency value of a height distribution on the outer circumferential surface is 1 ?m to 3 ?m.

Abstract: A charging member includes a conductive support and an outermost layer disposed on the conductive support. The outermost layer includes porous silica and an N-alkoxymethylated polyamide and has a gel fraction of 50% or more and a surface roughness Rz of 2 ?m or more and 20 ?m or less.

Abstract: A charging member includes a conductive support and an outermost layer disposed on the conductive support. The outermost layer includes porous silica and an N-alkoxymethylated polyamide and has a gel fraction of 50% or more and a surface roughness Rz of 2 ?m or more and 20 ?m or less.

Abstract: A charging member includes a conductive support and a surface layer provided on the conductive support, wherein electron emitting energy on a surface of the charging member is equal to or less than 10 cps0.5/eV.

Abstract: A charging member includes a conductive base material and a conductive outermost layer provided on the conductive base material, wherein the conductive outermost layer has a ten-point average surface roughness Rz of 2 ?m to 20 ?m and contains a resin and particles in which particles having a particle diameter of 5.0 ?m or more and a circularity of 0.8 or less are 30% by number or less with respect to the total number of particles having a particle diameter of 5.0 ?m or more and particles having a particle diameter of less than 5.0 ?m and a circularity of 0.8 or less are from 20% by number to 80% by number with respect to the total number of particles having a particle diameter of less than 5.0 ?m.

Abstract: An electrophotographic photoreceptor includes a conductive support, an undercoat layer that is provided on the conductive support and that has a thickness of from 15 ?m to 40 ?m and has light transmittance of 20% or less with respect to light having a wavelength of 450 nm when the thickness is at least 15 ?m, a charge generation layer that is provided on the undercoat layer, and a charge transport layer that is provided on the charge generation layer and that has a thickness of from 15 ?m to 40 ?m and has light transmittance of 30% or less with respect to light having a wavelength of 450 nm when the thickness is at least 15 ?m.

Abstract: An image forming apparatus includes at least an electrophotographic photoreceptor having at least a conductive support, an undercoat layer, and a photosensitive layer; a charging device that charges the surface of the electrophotographic photoreceptor in a contact charging mode, in which only DC voltage is applied; an electrostatic latent image forming device that exposes the surface of the charged electrophotographic photoreceptor to form an electrostatic latent image; a developing device that develops the electrostatic latent image by a developer to form a toner image; and a transfer device that directly transfers the toner image from the electrophotographic photoreceptor to a transfer medium; and does not include an erasing device for erasing the surface of the electrophotographic photoreceptor after the toner image is transferred onto the transfer medium by the transfer device and before the surface of the electrophotographic photoreceptor is charged by the charging device.

Abstract: An electrophotographic photoreceptor includes a conductive support, and an undercoat layer, a charge generation layer, and a charge transport layer that are provided in this order on the conductive support, wherein the undercoat layer includes at least metallic oxide particles, a reactive acceptor substance including an anthraquinone structure expressed by the following Formula 1, and a binder resin, the charge generation layer includes hydroxygallium phthalocyanine as a charge generation material, and a reflectance of incident light having a wavelength of 780 nm on a surface of the charge generation layer when the charge transport layer is removed is 17% or greater: wherein the anthraquinone structure expressed by Formula 1 is bonded to another structure at a position of *, and thus forms the reactive acceptor substance, and in Formula 1, n1 represents an integer of 1 to 7.