Abstract: An image forming apparatus includes a charging roller including elastic and surface layers and a photoconductor drum. Initially, the surface layer has a surface roughness Rz of 3-6 ?m, and the layers have an impedance ratio of 0.81 or less in absolute value at a frequency of 800-3000 Hz. After a predetermined time, the surface roughness Rz is reduced by a decrement ?Rz of 0.1-4 ?m. The drum has a film thickness D initially ranging from 20-40 ?m and reduced by a decrement ?D of 5-25 ?m after the predetermined time. Herein, 0.005??Rz/?D?0.8 holds. The impedance ratio is represented as ZE/(ZE+ZS) wherein ZE and ZS represent the respective impedances of the elastic layer and the surface layer, and 100k A4-size recording media recorded with images with an area coverage of 7% are printed in the predetermined time.

Abstract: A charging member includes a conductive elastic layer, and a conductive surface layer that is disposed on the conductive elastic layer, is in contact with an image holding member, and contains a resin, porous resin particles, and silicone oil, wherein a content of the porous resin particles is from 3 parts by weight to 25 parts by weight based on 100 parts by weight of the resin, and a content of the silicone oil is from 0.1 part by weight to 10 parts by weight based on 100 parts by weight of the resin.

Abstract: An image forming apparatus includes a charging roller including elastic and surface layers and a photoconductor drum. Initially, the surface layer has a surface roughness Rz of 3-6 ?m, and the layers have an impedance ratio of 0.81 or less in absolute value at a frequency of 800-3000 Hz. After a predetermined time, the surface roughness Rz is reduced by a decrement ?Rz of 0.1-4 ?m. The drum has a film thickness D initially ranging from 20-40 ?m and reduced by a decrement ?D of 5-25 ?m after the predetermined time. Herein, 0.005??Rz/?D?0.8 holds. The impedance ratio is represented as ZE/(ZE+ZS) wherein ZE and ZS represent the respective impedances of the elastic layer and the surface layer, and 100 k A4-size recording media recorded with images with an area coverage of 7% are printed in the predetermined time.

Abstract: A charging roller includes a conductive core, a resistive elastic layer disposed on the conductive core, and a surface layer disposed on the resistive elastic layer. The impedances of the resistive elastic layer and the surface layer measured at an environmental temperature of about 10° C. and a humidity of about 15% RH in a range of alternating voltage frequencies of an image-forming apparatus used satisfy: |ZE/(ZE+ZS)|?0.81 where ZE is the impedance of the resistive elastic layer, and ZS is the impedance of the surface layer.

Abstract: A charging member includes a conductive metal shaft and a conductive elastic layer. The conductive elastic layer comprises a rubber material containing 50% to 100% by weight of epichlorohydrin rubber containing 56 mol % or more of an ethylene oxide and a calcium oxide having an average particle size D50 of 18 ?m or smaller.

Abstract: Disclosed is a roll member including a core, and an elastic layer arranged on the core, the elastic layer containing a rubber material and polyalphaolefin.

Abstract: A charging member includes a conductive metal shaft and a conductive elastic layer. The conductive elastic layer comprises a rubber material containing 50% to 100% by weight of epichlorohydrin rubber containing 56 mol % or more of an ethylene oxide and a calcium oxide having an average particle size D50 of 18 ?m or smaller.

Abstract: An electrostatic charging member includes a base material; and an outermost layer that contains a porous filler and a resin and has a gel fraction of at least about 50% and a surface roughness Rz in a range of about 2 ?m to about 20 ?m.

Abstract: An electrostatic charging member includes a base material; and an outermost layer that contains a porous filler and a resin and has a gel fraction of at least about 50% and a surface roughness Rz in a range of about 2 ?m to about 20 ?m.

Abstract: The invention provides a charging device including a charging roll and a voltage application unit which is capable of applying to the charging roll a voltage in which an alternating current voltage is superimposed on a direct current voltage, the alternating current (Iac) which flows through the charging roll satisfying the following Equation (1), the charging roll satisfying the following conditions (a) to (c), and the charging roll contacting an image supporter to charge the image supporter: Iac/I(inflection)?1.2??Equation (1) (in the Equation (1), I (inflection) represents the flexion point of lac) (a) the fluctuation of the outside diameter is 0.1 mm or less (b) resistance (common logarithm) is 9.0 log·? or less (c) resistance variation (common logarithm) is 0.5 log·? or less.

Abstract: The invention provides a charging device including a charging roll and a voltage application unit which is capable of applying to the charging roll a voltage in which an alternating current voltage is superimposed on a direct current voltage, the alternating current (Iac) which flows through the charging roll satisfying the following Equation (1), the charging roll satisfying the following conditions (a) to (c), and the charging roll contacting an image supporter to charge the image supporter: Iac/I(inflection)?1.2 ??Equation (1) (in the Equation (1), I(inflection) represents the flexion point of lac) (a) the fluctuation of the outside diameter is 0.1 mm or less (b) resistance (common logarithm) is 9.0 log·? or less (c) resistance variation (common logarithm) is 0.5 log·? or less.

Abstract: An electro-conductive roll is provided that makes contact with a body to be charged in a state in which a voltage is applied thereto, and charges the body to be charged, a surface of the electro-conductive roll satisfying the following conditions (a) and (b): (a) the surface of the electro-conductive roll has a 10-point average roughness of 5 ?m or less; and (b) the surface of the electro-conductive roll has a dynamic ultra-microhardness in the range of 0.04 to 0.5.

Abstract: An electro-conductive roll is provided that makes contact with a body to be charged in a state in which a voltage is applied thereto, and charges the body to be charged, a surface of the electro-conductive roll satisfying the following conditions (a) and (b):

Abstract: The present invention provides an electrostatic charging member excellent in dispersibility of electrically-conducting agent and uniformity in resistance which causes no contamination of the material to be charged for a prolonged period of time. The present invention relates to an electrostatic charging member which electrostatically charging uniformly the surface of a material to be charged such as photoreceptor and dielectric material while pressing the material. An electrostatic charging member 1 has a two-layer structure comprising an electrically-conductive elastic material layer 1b formed on an electrically-conductive substrate 1a, and a resistance-controlling layer 1c covering the elastic material layer 1b. The resistance-controlling layer 1c comprises an electrically-conducting agent such as carbon black having a pH value of not more than 6 dispersed in an amine-modified polyurethane resin as a base polymer.

Abstract: Semiconductive members such as charging members, copying members, pressure fixation rolls, electricity removing members and the like having a small environmental dependence are provided. The semiconductive member of the present invention contains a semiconductive substrate, a conductive rubber layer, an intermediate layer, a resistance control layer the constituent material of which is a polyurethane ionomer having an ionic segment in the molecule, and a surface layer. The ionic segment is selected from among a sulfonic acid group, a carboxyl group and a tertiary amino radical, or the salts thereof. In addition, the glass transition temperature of this polyurethane ionomer is 30.degree. C. or less, and the volume specific resistance value is in the range of 10.sup.6 to 10.sup.9 W cm.

Abstract: A charging member is disclosed, which charges an electrifiable member, e.g., a photoreceptor, when a voltage is applied thereto while the charging member is kept being pressed against the electrifiable member. This charging member 1 comprises an electroconductive substrate 1a and, fixed thereto, an electroconductive elastomer layer 1b comprising at least a crosslinked silicone rubber, in which the content of uncrosslinked silicone polymer components having a number-average molecular weight of 10,000 or higher is not higher than 1% by weight. The crosslinked silicone rubber is preferably a reaction product obtained by reacting a liquid polymethylsiloxane containing at least two vinyl group substituents and having a viscosity of 3,000 cP or lower with a polyorganohydrogensiloxane as a crosslinking agent in the presence of a platinum catalyst. The charging member need not have an antifouling layer for inhibiting the migration of low-polymerization-degree components to an electrifiable member.