Abstract: A developing roller has a mandrel, an elastic layer and a cover layer as a surface layer. The cover layer includes a silicon oxide film containing a carbon atom chemically bonded to a silicon atom. In the silicon oxide film, the proportion of the total number of the elements of silicon, oxygen, carbon and hydrogen to the number of all detected elements, as detected with a high-frequency glow discharge light-emission surface analysis method, is 90% or more. The silicon oxide film has an abundance ratio of an oxygen atom chemically bonded to a silicon atom to silicon atoms, (O/Si), of 0.65 or more but 1.95 or less and an abundance ratio of a carbon atom chemically bonded to a silicon atom to silicon atoms, (C/Si), of 0.05 or more but 1.65 or less, and has a ratio of the maximum value to the minimum value of the (C/Si) in a thickness direction of the cover layer, of 1.50 to 33.00.

Abstract: A developing device for an image forming apparatus of a non-magnetic one-component type. The developing device has a developing roller having a body and a shaft. Bearings for supporting the shaft have a groove made in a contact surface that is in contact with the shaft, and grease is pooled in the groove. The contact surface of the shaft has a surface roughness from 0.2 to 0.5, and the grease has consistency from 265 to 385 ( 1/10 mm·20° C.).

Abstract: A developing device is usable with an electrophotographic image forming apparatus including a shaft and a rotary unit mounting the device. When mounted, the device is movable perpendicular to a shaft axial direction in response to movement of the rotary unit and the shaft is not movable in that direction. The device includes a developing roller that contacts and separates from a drum in response to movement of the rotary unit, and a coupler transmitting a rotating force to the roller. The coupler includes a portion engaging the shaft to receive a rotating force and a portion transmitting the received rotating force to the roller. The coupler takes a first position for transmitting the rotational force to the roller, a position before the coupler engages the shaft and is inclined away from the first position, and a position for the disengagement of the coupler and the shaft.

Abstract: A roller for use in a developing unit of an image forming apparatus may include a non-conductive shaft member and a non-conductive member to surround at least a part of an outer periphery of the shaft member. The shaft member may include a cylindrical rolling part and a pair of support parts formed to project from both ends of the rolling part in a lengthwise direction. The rolling part of the shaft member may be arranged opposite a charge roller in a developing unit and may rotate in contact with the charge roller to absorb and remove foreign substances adhered to a surface of the charge roller.

Abstract: The present invention intends to provide a method of producing a developing roller capable of providing high-quality electrophotographic images under a variety of environments. The method of producing a developing roller according to the present invention is a method of producing a developing roller having a mandrel, a resin layer on the outer periphery of the mandrel, and a surface layer on the outer periphery of the resin layer, the method including the step of curing a mixture containing a carbon black, a specific diol, and a specific isocyanate compound to form the surface layer.

Abstract: An objective is to provide a developing roller in which increase of residual potential is inhibited during repetitive operation without deteriorating interlayer adhesion, and prepared is a layer immediately below the surface capable of preventing fog caused by toner scattering, accompanied with a surface layer capable of preventing stains formed from foreign matters adhered to the surface, as well as preventing image unevenness since toner electrification is even under the presence of appropriate elasticity, and also to provide a image forming method employing the developing roller. Disclosed is a developing roller possessing an elastic layer made of silicone rubber provided around a conductive shaft, and a plurality of resin layers further provided on the elastic layer, wherein an outermost surface layer among the resin layers comprises silicone copolymerization polyurethane; and a layer immediately below the surface layer comprises a polyurethane resin-silica hybrid.

Abstract: A developing roller has a surface layer which can effectively inhibit the bleeding of a low-molecular-weight component from an elastic layer, and can efficiently impart a high electric charge to a negatively chargeable toner, and is excellent in toner-releasing properties. The developing roller has a mandrel, at least one layer of an elastic layer provided on the mandrel and a surface layer provided on the elastic layer, carries and conveys a toner, and develops an electrostatic latent image on an opposing photosensitive member with the toner. The surface layer comprises a silicon compound film containing Si, N, C and H having specific total amounts of the existing elements Si, N, C and H, and specific ratios N/Si, C/Si, and H/Si.

Abstract: This invention relates to a developing device 18 for use in an image-forming apparatus comprising a developing roller 100 having a conductive base surface 19 which may be covered with a resin layer 17 layer comprising an ion conductive material and a silicone-modified urethane resin having an ether structure.

Abstract: An image forming apparatus includes an image carrier that carries an electrostatic latent image on a surface thereof, a toner carrying roller that is disposed to face the image carrier and rotates in a predetermined rotation direction with charged toner carried on a surface thereof so as to transport the toner in an opposing position for facing the image carrier, and a bias applying unit that develops the electrostatic latent image with the toner by applying an AC voltage as a developing bias to the toner carrying roller. In addition, periodical concavo-convexes that are formed of a plurality of convex portions arranged at a constant pitch in a circumferential direction and concave portions that surround the plurality of convex portions are formed on the surface of the toner carrying roller.

Abstract: A developing roller is provided having a surface that has excellent effect of suppressing exudation of low molecular weight substances from an elastic body, excellent toner release properties, and sufficient flexibility in which cracks do not easily occur even by repeated image formation. The developing roller carries and conveys toner to develop electrostatic latent images on a photosensitive drum with the toner and includes in this order a mandrel, an elastic layer, and a surface layer. The surface layer includes a silicon oxide film containing carbon atoms chemically bonded to silicon atoms. The silicon oxide film has an abundance ratio of oxygen atoms forming chemical bonds with silicon atoms to silicon atoms (O/Si) of 0.65 or more and 1.95 or less, and an abundance ratio of carbon atoms forming chemical bonds with silicon atoms to silicon atoms (C/Si) of 0.05 or more and 1.65 or less.

Abstract: A developing device includes: a housing that stores toner therein; a toner carrying roller that is attached to the housing by a shaft and is rotated in a predetermined rotation direction while carrying charged toner on a surface of the toner carrying roller to transport the toner to the outside of the housing; and a seal member that extends in a direction of a rotation axis of the toner carrying roller and has one end fixed to the housing and the other end in contact with the surface of the toner carrying roller to prevent the toner from leaking out of the housing, wherein a plurality of convex portions having top surfaces constituting a part of the same cylindrical surface are formed on the surface of the toner carrying roller, and at least a part of the seal member in contact with the surface of the toner carrying roller is made of a material having a contact angle of 105° or more with respect to water.

Abstract: Developing roller comprising a conductive mandrel with at least an elastic conductive base layer and a charge providing layer. The base layer is located closer to the mandrel than the charge providing layer. The base layer is roughened before the charge providing layer is applied to the base layer.

Abstract: A conductive coating is described, suitable for coating a developer, charge or transfer roller in a developing apparatus to give a charge providing layer. The coating comprises a conductive polymer in a matrix. A roller is also described, suitable for a developing apparatus comprising, from the centre to the periphery, a conductive mandrel, a conductive elastic base layer and a charge providing layer.

Abstract: A developing roller composed of a rubber member including not less than two vulcanized rubber layers including a surface layer and a base layer. A hardness of the surface layer is set higher than that of the base layer. The hardness of the base layer is set to not more than 60 degrees in a JIS A hardness. A hardness of a laminate of all layers including the base layer and the surface layer is set to not more than 70 degrees in the JIS A hardness. An electric resistance value of the laminate is set to not more than 1010?, when the electric resistance value is measured by applying a voltage of 100V to the laminate at a temperature of 10° C. and a relative humidity of 20%.

Abstract: A developer bearing member on which grooves slanting in a thrust direction of the developer bearing member cross other grooves reversely slanting relative to the thrust direction, wherein each of the grooves and the reversely slanting grooves is slanting at an angle of greater than 0° and not greater than 40°. Any two adjacent intersections of the grooves and the reversely slanting grooves in the thrust (or peripheral) direction are preferably on different levels in the peripheral (or thrust) direction. The distance between two adjacent intersections in the thrust direction is preferably from 1.3 mm to 4.8 mm. The distance between two adjacent intersections in the thrust direction is preferably from 0.38 Vd/Vi (mm) to 1.1 Vd/Vi (mm). The deviation in depth of grooves present on a 36° arc surface portion of the member is not greater than 15% of the gap between the image bearing member and the developer bearing member.

Abstract: An apparatus includes: a rolling die having protruding threads and a feeding unit moving the workpiece by L1 per rotation. The rolling die includes: a straight portion maintaining a distance between a top of each protruded thread and an axial line of the rolling die nearly constant; and two tapered portions gradually reducing the distance outward from both ends of the straight portion. At least one tapered portion downstream of the workpiece has a width larger than L1, and a distance r1 between the top of each protruded thread and the axial line direction of the rolling die in the straight portion and a distance r2 between the top of each protruded thread and the axial line direction of the rolling die at a portion separated from a boundary between the straight portion and the one tapered portion by L1 satisfies the relation r1?r2?5 micrometers.

Abstract: In the present invention, provided can be a developing roller through which neither fog nor contamination inside the apparatus is generated, and no insufficient image density is produced, even though printing a large number of paper sheets (5000 paper sheets, for example). Also disclosed is a developing roller possessing a conductive shaft and a coating layer provided on an outer circumference of the conductive shaft, wherein the coating layer possesses a resin and a surface roughness particle, and the coating layer surface has a surface roughness Ra of 0.5-2.5 ?m and a Young's modulus Y of 1-200 MPa.

Abstract: The invention offers a method of producing an OA apparatus roller that can increase the thermal conductivity of the surface layer composed of a fluororesin layer by decreasing its thickness, that has an excellent parting ability, that can prevent the rubber layer from deteriorating, and that is free from foreign matters adhering onto the inner surface of a hollow cylindrical mold even when the hollow cylindrical mold is used. The invention also offers an OA apparatus roller produced by the foregoing method. The method of producing an OA apparatus roller is provided with a step of forming an elastic layer and a surface layer in this order on a core metal. In this method, the surface layer is formed by using a fluororesin dispersion and the fluororesin dispersion contains a surfactant, a film-thickening agent, and a viscosity-increasing agent with a total content of 1.0 to 5.0 wt %.

Abstract: A conductive roller comprising a toner-transporting portion, made of a vulcanized rubber composition, which is disposed at least on an outermost layer thereof. The vulcanized rubber composition contains a rubber component (A) mixed with a weakly conductive carbon black (B) having a large particle diameter not less than 80 nm nor more than 500 nm, a highly conductive carbon black (C) having a small particle diameter not less than 18 nm nor more than 80 nm, and an inorganic filler (D) consisting of not less than one kind of a metal oxide selected from among a group of titanium oxide, alumina, and silica. The total of a mixing amount of the weakly conductive carbon black (B), that of the highly conductive carbon black (C), and that of the inorganic filler (D) for 100 parts by mass of the rubber component (A) is not less than 15 parts by mass nor more than 60 parts by mass.

Abstract: A developer carrier which holds a developer on a surface and is rotatable includes: a plurality of grooves which is formed on the surface, wherein each of the grooves is wavy-lined, an inclination direction of the grooves to an axis of the developer carrier is cyclically changed in an opposite direction, and the grooves are respectively arranged at intervals.

Abstract: A developing device includes a developer supporting member for supporting developer and a developer charging member disposed to face the developer supporting member for charging and supplying the developer to the developer supporting member. The developer supporting member has a surface having a calculated average surface roughness Ra between 0.1 ?m and 0.6 ?m and a surface free energy SFE between 15 mN/m and 26 mN/m. Further, the developer charging member has an Asker F hardness Haf between 24° and 56°.

Abstract: A development roller includes a base unit having a base recess and a base projection that are formed in a predetermined area of a circumference surface of the base unit, and a surface layer formed on the circumference surface of the base unit and having on the circumference thereof a recess and a projection formed respectively in accordance with the base recess and the base projection of the base unit. Surface hardness of the projection is higher than surface hardness of the recess.

Abstract: A developing roller has a conductive shaft member, a conductive elastic layer formed around the shaft member in a thickness of 0.5 mm to 6.0 mm, and a surface layer. The elastic layer contains carbon black and silicone rubber. The carbon black is in a content of 7% to 17% by mass and has at least two peaks in its particle size number distribution. The minimum diameter peak center in the particle size number distribution is within the range of 10 nm to 40 nm. The elastic layer has density within the range of 1.01 g/cm3 to 1.07 g/cm3. Where the ratios of carbon atoms to silicon atoms (C/Si), in the vicinity of the surface of the elastic layer, at depths of 100 ?m and 200 ?m from the surface of the elastic layer are represented by X, Y and Z, respectively, the X, Y and Z satisfy a specific relationship.

Abstract: A development roller includes a base unit having a base recess and a base projection that are formed in a predetermined area of a circumference surface of the base unit by pressing a regular pattern in pressure machining, and a surface layer formed on the circumference surface of the base unit and having a recess and a projection formed respectively in accordance with the base recess and the base projection of the base unit. A thickness of the surface layer is larger than a maximum height of a base swollen portion close to the side edge of the base projection from a regular surface of the base projection.

Abstract: A development roller includes a base unit having a base recess and a base projection formed in a predetermined area of a circumference surface of the base unit, and a surface layer formed on the circumference surface of the base unit and having a recess and a projection formed respectively in accordance with the base recess and the base projection of the base unit.

Abstract: A technique that makes it possible to switch high-torque power transmission with a compact and simple configuration is provided. A driving force transmitting device that transmits driving force received by one of a first rotating body and a second rotating body to the other includes: the first rotating body; a first engaging section that is provided in the first rotating body; the second rotating body that rotates around a rotating shaft the same as that of the first rotating body; elastically deforming sections that are arranged in the second rotating body; and a second engaging section that is provided in the second rotating body and elastically supported by the elastically deforming sections to engage with the first engaging section and is disengaged from the first engaging section by centrifugal force involved in the rotation of the second rotating body.

Abstract: A developing roller having an elastic layer on the outer periphery of a mandrel and having a surface layer containing a resin and resin particles on its outer periphery, wherein the surface layer has a convex portion attributable to the resin particles, and has a surface of roughness in which a distortion degree Rsk of a roughness curve is 0.15 or more and 0.70 or less, wherein the resin particles have a peak P1 at a particle diameter d1 in a volume particle size distribution, and wherein “a”, “b”, “c”, d1, d2 and d3 satisfy a specific relationship, where, “a” denotes a volume fraction of the resin particle having the particle diameter d1 in the volume particle size distribution, and “b” and “c” denote volume fractions at particle diameters d2 and d3 respectively in the volume particle size distribution.

Abstract: Exemplary embodiments provide a roll member that includes one or more linear arrays of actuator cells and methods for making and using the roll member. In one embodiment, each linear array of the roll member can be controllably actuated as a group by, e.g., an oscillating voltage, to release toner particles adhered thereto and to form a uniform toner cloud in the development area between the roll member and an image receiving member. The controllable actuation can also aid in the unloading process of the residual toner particles from the roll member. In various embodiments, the uniform toner cloud and/or the controllable unloading process can enable a non-interactive development system for image-on-image full-color printing.

Abstract: A method of manufacturing a toner carrier roller that is shaped like a cylinder on an outer circumferential surface of which concave and convex sections for carrying toner are provided, includes: preparing a roller base member which is shaped like a cylinder; forming helix-like first grooves on the outer circumferential surface of the roller base member; and forming helix-like second grooves, which cross the first grooves, on the outer circumferential surface of the roller base member, wherein a pitch ratio of the first grooves and the second grooves is a non-integer ratio.

Abstract: A developing device includes a developer supporting member having an elastic layer and a surface layer, and a supply member for supplying developer to the developer supporting member. The surface layer is formed of a mixture containing at least an acrylic resin and a polyether type urethane resin. The developer supporting member and the supply member are configured so that the following equations are satisfied: 20?A1?80 0.6?D?2.0 45+0.1×A1×D?F×N?65 where A1 is a weight ratio (%) of the acrylic resin relative to a total weight of the acrylic resin and the polyether type urethane resin, F is an Asker F hardness (degree) of a surface of the supply member, and N is an overlap amount (mm) representing a biting amount of the supply member relative to the developer supporting member.

Abstract: A developing device, includes: a housing that stores toner inside; a toner carrier roller that is shaped approximately like a cylinder, is mounted to the housing rotatably about a rotational axis, rotates while carrying the toner on a surface thereof to convey the toner to outside of the housing, and is provided, on the surface thereof, with a plurality of convex sections which are regularly arranged and a concave section which surrounds the convex sections, the convex sections including top surfaces that coincide with a part of a curved surface of single cylinder and have electrical conductivity; and a seal member that is arranged in abutting contact with the surface of the toner carrier roller moving from the outside the housing toward the inside the housing at a position downstream of the opposed position in a rotation direction of the toner carrier roller to prevent toner leakage from the housing, a contact surface of the seal member being made of a material located at a position to charge the toner with

Abstract: A developing device includes a container that contains toner particles that are for developing a latent image borne by an image bearing body, and a toner-particle bearing roller that has a helical groove portion on a surface thereof that is for bearing the toner particles, the helical groove portion having an inclination with respect to an axial direction and a circumferential direction of the toner-particle bearing roller and being formed having a uniform pitch in the axial direction.

Abstract: A developing unit includes a developing roller which rotates about a rotational axis to supply toner to a photoreceptor, the developing roller including: a cylindrical core portion which includes an electric conductor; a first resistive layer which covers a cylindrical surface of the core portion; a second resistive layer which covers the first resistive layer, and has electric-resistivity lower than that of the first resistive layer; and a current leakage control member which prevents leakage of electric current from the core portion toward the second resistive layer through an end of the developing roller along a direction of the rotational axis.

Abstract: Provided is an image forming apparatus including at least a latent image bearing member, a latent electrostatic image forming unit, a developing unit which includes at least a developing roller and a supply roller, and a transfer unit, wherein both of a diameter R (mm) of the developing roller and a diameter R? (mm) of the supply roller are 12 mm or less; the toner contains at least a binder resin, a wax, and a colorant with the wax having a melting point of 75° C. or less; an amount of the wax exposed on a surface of the toner is 10 mg/g to 30 mg/g; and when a diameter (mm) of the developing roller is represented by R the toner has a torque T (mNm) satisfying the inequation, 20/R<T<27/R, at a void rate of 58% as measured by a torque measurement method using a conical rotor.

Abstract: A developing roller including a semiconductive rubber member having not less than two vulcanized layers including a base layer composed of a vulcanized electro-conductive rubber composition and a surface layer composed of a vulcanized rubber composition. An electric resistance value of the base layer is set to not more than 107?, when the electric resistance value of the base layer is measured by applying a voltage of 100V thereto at a temperature of 10° C. and a relative humidity of 20%. An electric resistance value of a laminate of all layers including the base layer and the surface layer is set not more than 107? in the same condition as the above-described condition in which the electric resistance value of the base layer is measured.

Abstract: An image forming apparatus includes: an image bearing body that is rotatable about a central axis thereof, and that bears a dot-like latent image, on a surface of the image bearing body, in each of a plurality of divided regions that are arranged in rows along a direction that intersects an axial direction of the central axis at a predetermined intersection angle; and a developer bearing roller that is rotatable in order to make visible, as a developer image, the dot-like latent images borne by the image bearing body, using a developer borne on a surface of the developer bearing roller, the developer bearing roller opposing the image bearing body such that an axial direction of the developer bearing roller is parallel to the axial direction of the image bearing body, and that includes a helical groove portion on the surface of the developer bearing roller, the helical groove portion being inclined at a predetermined inclination angle with respect to the axial direction of the developer bearing roller and bein

Abstract: A conductive rubber roller and transfer roller whose resistance value is easily controlled and which lowers contamination of a charged member and has excellent electric variability and compressive permanent set is provided at low cost. There is provided a conductive rubber roller for use in an electrophotographic process, wherein a rubber component of the conductive rubber roller has at least acrylonitrile butadiene rubber whose acrylonitrile content is 15% by mass to 25% by mass (both inclusive) and weight average molecular weight (Mw) is 500,000 to 1,000,000 (both inclusive), and epichlorohydrin type rubber whose ethylene oxide content is not less than 70% by mole to less than 90% by mole; and the acrylonitrile butadiene rubber is contained in an amount of 5 parts by mass to 80 parts by mass (both inclusive) in 100 parts by mass of the rubber component.

Abstract: A developer apparatus, includes: a toner carrier roller that is shaped approximately like a cylinder, rotates while carrying a toner layer of charged toner on a surface thereof, and is provided, on the surface thereof, with plural convex section rows, each of which has plural convex sections arranged in a row in a width direction parallel to a rotational axis of the toner carrier roller and which are arranged in a circumferential direction orthogonal to the width direction and parallel to a circumferential surface of the toner carrier roller, the convex sections being so constructed and arranged that top surfaces of the convex sections coincide with a part of a curved surface of a single cylinder; and a restriction member that abuts on the surface of the toner carrier roller to restrict the toner layer carried on the surface of the toner carrier roller, includes an elastic abutting member which is made of an elastic material and has an edge part which extends in the width direction, the edge part being presse

Abstract: A roller device for a toner cartridge includes a spindle and a roller body. The roller body has a foam layer disposed around the spindle, and an outer tube disposed around the foam layer. Both of the outer tube and the foam layer are made of a thermoplastic material. The roller body has a bulk resistance ranging from 102 ohms to 1010 ohms.

Abstract: The present invention provides a developer holding member having a surface layer composed of metal on or above a roughened hollow cylindrical substrate, wherein the specular gloss at 60°, Gs (60°), of the surface layer is in the range of approximately 10 to 40 gloss units, a developing apparatus and image-forming apparatus having the developer holding member, and a method of producing the developer holding member.

Abstract: A developing roller having an elastic layer on the outer periphery of a mandrel and having a surface layer containing a resin and resin particles on its outer periphery, wherein the surface layer has a convex portion attributable to the resin particles, and has a surface of roughness in which a distortion degree Rsk of a roughness curve is 0.15 or more and 0.70 or less, wherein the resin particles have a peak P1 at a particle diameter dl in a volume particle size distribution, and wherein “a”, “b”, “c”, d1, d2 and d3 satisfy a specific relationship, where, “a” denotes a volume fraction of the resin particle having the particle diameter dl in the volume particle size distribution, and “b” and “c” denote volume fractions at particle diameters d2 and d3 respectively in the volume particle size distribution.

Abstract: A development roller is provided which can ensure a desired surface roughness and roller hardness even when an elastic layer has not sufficient solvent resistance and which can be preferably used for a long period of time without generating any peeling of a coating film during a continuous long operation. In the development roller, an underlying conductive layer having at least one sublayer and a surface resin layer are provided on the elastic layer in that order. The elastic layer is formed of a foam material having a closed cell structure, the underlying conductive layer is formed from a water-based paint containing a conductive agent, and one of the sublayers of the underlying conductive layer that is in contact with the elastic layer is at least primarily composed of a chloroprene-methacrylic acid copolymer.

Abstract: The present disclosure relates to controlling a performance characteristic of an image forming device component having a surface which may include removal of a portion of the surface to expose a plurality of voids and a surface between the voids. The surface between the voids may have a surface roughness Ra in the range of 0.1 to 5.0 microns and the relationship SAV/(SAV+SAC) is equal to 1-50%, where SAV is the surface area of the voids and SAC is the remaining surface area of the component. The performance characteristic may include the control of toner mass conveyed and/or toner filming and/or the amount of residual toner removed from a photoconductive surface.

Abstract: A cleaning device comprises a toner conveying mechanism, wherein the toner conveying mechanism includes a conveying member that rotates to convey toner; and an elastic member that is furnished for contacting with circumference of the conveying member, wherein the elastic member contacts to circumference of the rotating conveying member with slide.

Abstract: The presently disclosed embodiments are directed to charge transport layers useful in electrostatography. More particularly, the embodiments pertain to an improved imaging member having a dual charge generation layer comprising a top layer and a bottom layer, wherein the bottom layer comprises a blend of phthalocyanine pigments having different sensitivities and morphologies.

Abstract: Provided are a developing roller for non-magnetic single component development and a developing method employing the developing, by which toner can be stably conveyed in any external environment, and the stable toner conveyance and charging amount can also be acquired. Also disclosed is a developing roller possessing a spindle and provided around an outer circumference of the spindle, at least an elastic layer (innermost layer), a resistance adjusting layer (intermediate layer) formed on the elastic layer and a surface layer (outermost layer) formed on the resistance adjusting layer, wherein the intermediate layer possesses a layer containing carbon black in a resin, a content of a polycyclic aromatic hydrocarbon in the carbon black is at most 10 ppm, and a volume resistance (Rv) of all the layers provided around the outer circumference of the spindle is 1.0×107?1.0×1013 ?·cm.

Abstract: The present invention provides an electrophotographic photoconductor including, an uppermost crosslinked surface layer including a cured product of a crosslinked surface layer composition containing a tri- or more functional radical-polymerizable monomer having no charge transportable structure, organosilica sol, an isocyanate group-containing radical-polymerizable monomer, and a curable charge transport material.

Abstract: A copolymer obtained by copolymerizing at least one monomer selected from specific acrylate or methacrylate monomers, at least one monomer selected from specific amino group-containing monomers and at least one monomer selected from specific polar group-containing monomers. A resin for electrophotographic functional component parts, which contains this copolymer, a developing roller in which a cover layer serving as a surface layer contains the copolymer as a positive charge control resin, and an electrophotographic apparatus that includes the developing roller.

Abstract: A rotation member unit detachable from a casing includes a rotation member for rotating when driven, and plural drive introduction members arranged at both ends of the rotation member in a rotation axial direction of the rotation member, respectively. The drive introduction member engages with a drive transmission member rotated by a motor.

Abstract: An electrostatic image developing toner including a binder resin; and a colorant, and satisfying following conditions (1) and (2): 0.02?CA/CB?0.20??(1) 1?Nt/St?15??(2) wherein CA represents an amount of a carboxyl group and its salt on a surface of the toner, CB represents an amount of a carboxyl group and its salt in the entire toner, Nt represents an amount of a nitrogen element on the surface of the toner, and St represents an amount of a sulfur element on the surface of the toner.