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: The objective of the present invention is to provide a developing roller that can form a toner image with high quality. The present invention relates to a developing roller comprising: a supporting shaft, and at least one resin layer formed on a peripheral face of the supporting shaft, the resin layer containing carbon black in which a number average Feret's diameter is in a range from 5 to 300 nm and primary particles account for 5% or more on a number basis, and the carbon black being dispersed in a base resin material thereof.

Abstract: A developer unit according to one aspect of the invention includes: a developer accommodation member configured to accommodate a developer, the developer having charging polarity to a first polarity; a developing roller arranged at the developer accommodation member, the developing roller being configured to carry the developer; a supply roller arranged at the developer accommodation member, the supply roller being configured to supply the developer to the developing roller; and a charging member brought into sliding contact with the supply roller. The charging member at a portion brought into sliding contact with the supply roller is formed of a material which is positioned on a side of the first polarity on a triboelectric series relative to the supply roller.

Abstract: A developing device is disposed facing an image bearing body that bears a latent image. The developing device includes a developer bearing body that bears a developer for developing the latent image. The developer includes mother particles and external additives. A liberation amount T (weight parts) of the external additives liberated from the mother particles with respect to 100 weight parts of the mother particles, a surface roughness Rz (m) of the developer bearing body, and a circumferential speed Vd (mm/s) of the developer bearing body satisfy the following relationships: 1.326×10?1?T?2.142×10?1(weight parts), 7.1×10?6?Rz?15.0×10?6(m), 161.5?Vd?189.2(mm/s), and 4.98×10?6?(T×Rz/Vd)?1.99×10?5(s).

Abstract: A developing roller is provided which is soft enough to enable toners to be kept from deteriorating with time and cannot easily cause permanent set. The developing roller includes a mandrel, an elastic-material layer and a cover layer as a surface layer which covers the elastic-material layer. Asker-C hardness at the surface of the cover layer is from 40° to 85°. The cover layer has a thickness of from 15 nm to 5,000 nm. Martens hardness H1 (N/mm2) at the surface of the developing roller, Martens hardness H2 (N/mm2) of the elastic-material layer and the thickness d (mm) of the cover layer satisfy the relationship of the following expression (1): 400?(H1?H2)/d?2,000??(1).

Abstract: The present invention provides an image-forming apparatus comprising a magnetic roll for magnetically holding a two-component developer in which toner and a magnetic carrier are electrostatically bonded, a developing roll in which a thin layer of the toner transferred from the two-component developer on the magnetic roll is formed on the surface, and a latent image support in which a latent image is developed with using the toner on the developing roll by a developing bias applied in relation to the developing roll, wherein the developing roll has a coating layer composed of silicone-modified polyurethane on a surface.

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: To provide a developing roller which makes it possible to sufficiently prevent toner leakage, with the driving torque of the developing roller being scarcely increased, and a mono-component developing apparatus having such a developing roller. A developing roller for a mono-component developing apparatus, which transports toner supported on an outer circumferential face of a center portion 12 toward a developing area by rotating while frictionally sliding on a sealing member on each of two end portions 11a, 11b, comprising: surface processing areas 13 having a spiral shape, placed on each of outer circumferential faces of the two end portions, wherein an angle ?, made by a spiral direction y of each surface processing area and the rotation direction x, is allowed to have an acute angle, and a mono-component developing apparatus having such a developing roller.

Abstract: A developing device including a developer bearing member configured to feed a developer to an image bearing member; a developer supplying member, which is contacted with the developer bearing member at a first nip while opposed thereto and which is configured to supply the developer to the developer bearing member; and a developer layer forming member, which is contacted with the developer bearing member at a second nip located on the downstream side from the first nip relative to the rotation direction of the developer bearing member to form the layer of the developer on the developer bearing member, wherein the developer is a nonmagnetic one component developer, and the distance between the front edge of the second nip and the rear edge of the first nip relative to the rotation direction of the image bearing member is greater than 0.8 mm and less than 2.0 mm.

Abstract: There are provided a developing roller capable of making useless a drying line in the formation of a resin layer and using a carbon-based electrically conducting agent for giving an electrical conductivity to the resin layer as well as an imaging apparatus using the same. The developing roller 1 comprises a shaft member 2 constituted with a hollow cylindrical body or a solid cylindrical body of a resin containing an electrically conducting agent and a resin layer 4. The resin layer 4 is made from a ultraviolet-curing type resin containing a carbon-based electrically conducting agent and a ultraviolet initiator, in which the ultraviolet initiator has a maximum wavelength in a ultraviolet absorption wavelength region of not less than 400 nm. The resin layer 4 may be made from an electron beam curing type resin containing the electrically conducting agent.

Abstract: The invention provides, as an aspect thereof, an image formation apparatus that includes: an image carrier that carries a latent image; a toner carrier that has, on a surface of the toner carrier, a concave portion arrayed in a regular pattern so as to carry toner, and develops the latent image that is carried on the image carrier by means of the toner carried in the concave portion; and a voltage application section that applies a development voltage to the toner carrier for the purpose of the development of the latent image. In the configuration of an image formation apparatus according to the above-described aspect of the invention, immediately after that the toner carrier has developed the latent image, which is carried on the image carrier, by means of the toner carried in the concave portion in response to the application of the development bias to the toner carrier by the voltage application section, at least one layer of the toner remains carried in the concave portion.

Abstract: A developing device is provided with a toner bearing member that bears toner having core particles and a particulate external additive externally added to the core particles, and that develops a latent image borne on an image bearing member using the toner, the toner bearing member being rotatable and having projecting sections arranged in a regular manner on a surface of the toner bearing member; and a regulation member that regulates an amount of toner borne on a surface of the toner bearing member by coming into contact with that surface at a contact section, the regulation member being arranged so that a longitudinal direction of the regulation member runs along an axial direction of the toner bearing member, and so that a leading edge of the regulation member in a lateral direction and a thickness direction faces an upstream side in a rotating direction of the toner bearing member, wherein in the case where a volume mean particle size of the toner is set to a toner particle size A, a volume mean particle

Abstract: The present invention provides a developing device that includes a toner bearing member that includes regularly arranged projection sections and depressed sections for bearing toner, and that develops a latent image borne on an image bearing member with the toner borne on the projection sections and the depressed sections, wherein the latent image is developed in a state in which a projection section covering ratio at which toner contacting the projection sections covers the projection sections is smaller than a depressed section covering ratio at which toner contacting the depressed sections covers the depressed sections.

Abstract: A developing device and an image forming apparatus which can form a printing image having high resolution and a high quality level, while resolving various problems resulted from the use of small particle size toner particles are provided. The developing device includes a toner constituted of resin base particles containing a coloring agent and a binder resin, and silicone oil and/or fluoro oil added to the resin base particles, a toner receiving portion for receiving the toner, and a developing roller having an outer peripheral surface and an irregularity section for carrying the toner, the irregularity section formed on the outer peripheral surface and including a plurality of depression portions and/or protrusion portions provided regularly and uniformly, wherein an average particle size of the resin base particles in volume basis is in the range of 2 to 4 ?m, and an added amount of the silicone oil and/or fluoro oil to the resin base particles is in the range of 0.05 to 2 mass %.

Abstract: This invention relates to a conductive roller such as a developing roller, a charging roller or the like provided with a resin coating calyer on a surface of an elastic layer, and more particularly to a conductive roller having the resin coating layer using an ultraviolet-curing type resin or an electron beam curing type resin and being obtained by contriving a structure of the resin coating layer, rendering the resin coating layer to contain microparticles, controlling the particle size of the microparticles, or forming the resin coating layer after the outer peripheral surface of the elastic layer is subjected to surface treatment.

Abstract: A regenerated elastic rollers manufacturing process is provided. The process includes the step of removing an agglutinated stain of toner adhered to the surface of an elastic roller including a mandrel and an elastic layer. The step further includes the steps of: (1) pressing a pressing roller against the surface of the elastic roller so as to crack the agglutinated stain on the surface of the elastic roller; and (2) removing the agglutinated stain cracked in the step (1) from the surface of the elastic roller by means of an adhesive roller.

Abstract: A developing roller for providing a magnetic brush for a printer or copier according to embodiments of the present invention has a substantially cylindrical outer surface. The outer surface comprises a regular or irregular array of a number of isolated areas, each isolated area being provided by a recess in the outer surface. Each recess is completely surrounded on all sides and isolated from any neighbouring isolated area by separation zones being part of the substantially cylindrical outer surface.

Abstract: An electrophotographic developing roller in which air tightness and electrical conductivity in a fit section between a cylindrical metal base body and a metal flange are satisfactory and outside diameter deflection accuracy is satisfactory; and an electrophotographic developing roller which is relatively inexpensive, excellent in mechanical rigidity, surface processability and plating film formation (corrosion resistance) and capable of being satisfied with a prescribed dimensional accuracy are provided. The electrophotographic developing roller is a developing roller having a cylindrical metal base body and a metal flange. The metal flange has a larger diameter section to be fitted in the opening end inner surface of the cylindrical metal base body and a smaller diameter section serving as a central shaft body coaxial with the cylindrical metal base body.

Abstract: To provide a developing device capable of preventing excess charge of the toner particles so as to prevent occurrence of failure caused by an decrease in toner flying property between the developing roller and photoconductor or a change in development characteristics, a developing device according to the present invention develops non-magnetic mono component toner using a developing roller having on its surface a plurality of groove portions each of which includes: a leading end side cut portion formed on the leading end side of the developing roller in the rotational direction thereof and having a leading end side cut angle ?1; and a trailing end side cut portion formed on the trailing end side of the developing roller in the rotational direction thereof and having a trailing end side cut angle ?2 and in which a relationship ?1<?2 is satisfied.

Abstract: A coating and developing system includes two rotating members 131 and 132 respectively having parallel horizontal axes of rotation and disposed longitudinally opposite to each other, a carrying passage forming mechanism 130 extended between the rotating members 131 and 132 to form a carrying passage, and capable of moving along an orbital path to carry a wafer W supported thereon along the carrying passage, a sending-in transfer unit 110 disposed at the upstream end of the carrying passage, a sending-out transfer unit 111 disposed at the downstream end of the carrying passage, a developer pouring nozzle 151 for pouring a developer onto the wafer W, a cleaning nozzle 152 for pouring a cleaning liquid onto the wafer W, and a gas nozzle 154 for blowing a gas against the wafer W.

Abstract: A developing roller for an electrographic imaging apparatus, which comprises a base rubber, a conductive carbon black, a conductive polymer for controlling hardness of the base rubber and dispersion of the carbon black, and a binder resin for inhibiting migration of the conductive polymer to a surface of the developing roller, and an electrographic apparatus comprising the same are provided. The developing roller has excellent hardness, processibility, stability to resistance and resistance to migration.

Abstract: To provide a positive charge control resin with which an electrophotographic functional component part coming into contact with a toner can be made chargeable in a polarity reverse to the polarity of the toner, and which has superior dispersibility in, and compatibility with, a main binder. The present invention is a positive charge control resin having a copolymer obtained by polymerizing specific acrylate or methacrylate monomer, amino-group-containing monomer(s) and carboxyl-group-containing monomer(s) as copolymerization components.

Abstract: An image forming apparatus including an image bearing member, a charging device, an irradiating device, a developing device, a transfer device, a fixing device, and a cleaning device, wherein the image bearing member includes a substrate on which a photosensitive layer and a cross-linked surface layer are accumulated and the cross-linked surface layer comprises a cross-linked material formed by curing a monomer having at least three radical polymerizable function groups without a charge transport structure and a radical polymerizable compound having a charge transport structure by a photo-energy irradiation device, wherein the toner has a volume average particle diameter of from 1 to 5 ?m and an average circularity of from 0.95 to 0.

Abstract: To provide a developer supply roller including:a shaft core; and an elastic layer over the shaft core, wherein the elastic layer is composed of at least a first elastic layer and a second elastic layer, the first elastic layer and second elastic layer made of elastic bodies with different moduli of elasticity, the first layer being an outermost layer of the supply roller, and wherein the relationships 0%?k1?20% and 20%?k2?70% are satisfied, where k1 is the modulus of repulsion elasticity of the first elastic layer and k2 is the modulus of repulsion elasticity (%) of the second elastic layer.

Abstract: A magnet roller for use with a hollow cylindrical structure made of a non-magnetic material includes a roller body and a reinforcing member. The roller body, encased in the hollow cylindrical structure, has at least one magnetic pole to form an agent releasing area on a skin of the cylindrical structure. The roller body is integrated with a shaft on each end portion of the roller body as one solid body. The reinforcing member is embedded in a portion of the roller body corresponding to the agent releasing area. The reinforcing member is made of a material different from a material used for the roller body and extends in an axial direction of the roller body.

Abstract: A developing device including a developing roller and a developer layer forming member for forming a layer of a one component developer on the roller. The developing device satisfies the relationships (1) 20<X<65?14?, and (2) 12.7??25>Q/M>13.1??44.5, wherein X represents the ratio (% by weight) of the wax present on the surface of the developer to the total of the wax therein; ? represents the angle formed by a tangent line to the member at a point B, which is the center of the contact zone of the member contacted with the roller, and another tangent line at a point A thereof 0.5 mm apart from the point B toward the tip of the member, wherein ? is 0 to ?/2 radian; and Q/M represents the charge quantity (?C/g) of the toner per unit weight.

Abstract: An image developer using a one-component developer, Including a developing roller visualizing an electrostatic latent image formed on an image bearer with a pulverized toner; and a feed roller feeding the pulverized toner to the developing roller while contacting thereto, wherein the pulverized toner includes a parent toner; a wax; and an external additive comprising an additive having a number-average particle diameter of from 20 to 60 nm and adhering to the surface of the parent toner at an adherence strength of from 50 to 70%, and wherein the following relationships (1) to (3) are satisfied: 4.70<Log10R<5.70 ??(1) 8.00<Log10Z<10.70 ??(2) ?6.25*Log10R+37.5<Log10Z<?6.25*Log10R+45.6 ??(3) wherein R represents a resistivity of the developing roller and Z represents an impedance of the pulverized toner.

Abstract: Objects of the present invention are to provide an image forming method and image forming apparatus which can secure stable toner transferability, prevent reverse transfer of the toner back to a latent image bearing member, have excellent fixing ability and produce high-quality images.

Abstract: A developing roller, having a surface layer composed of; a binder resin having an SP value in the range of 7.5 to 9.0; and roughness-imparting particles made from a resin having an SP value that has a difference from the SP value of said resin of 2 or less in the absolute value thereof, the roughness-imparting particles being dispersed in the binder resin, a developing device provided with the developing roller and an image-forming apparatus provided with such a developing device, a developing device provided with the developing roller, and an image-forming apparatus provided with the developing device equipped with the developing roller.

Abstract: An objective is to provide a developing roller possessing a surface layer capable of suppressing the residual potential during repetitive use with no damage of interlayer adhesiveness, preventing toner leakage and contaminations caused by adhesion matter on the surface, and preventing developing unevenness because of even toner electrification; and also to provide an image forming method employing the developing roller. Also disclose is a developing roller possessing a conductive shaft, and a resin layer provided around an outer circumferential surface of the conductive shaft, wherein the resin layer possesses a surface layer containing a silicone copolymer resin as a principal component and a layer containing a polyamide resin as a principal component, that is provided immediately below the surface layer.

Abstract: A developing roller for electrophotographic image forming apparatus is disclosed. The developing roller has a shaft and a resin layer, and the resin layer comprises a binder resin, a resin particle having a particle diameter of 5 ?m to 30 ?m and a content of from 10% to 50% by weight with respect to the resin layer, and inorganic oxide particles having a number based average primary particle diameter of 5 nm to 100 nm and a content of 1% to 40% by weight with respect to the resin layer. An image forming method employing the developer roller is also disclosed.

Abstract: Developer roll having a conductive or semi-conductive soft rubber core and a coating deposited in the soft rubber core wherein the coating has a conductive agent. The outer surface of the soft rubber core is modified before the coating is deposited onto the outer surface of the soft rubber core. Methods for making the same.

Abstract: An image forming apparatus including a photosensitive member on which an electrostatic latent image is formed, an image forming unit to form a visible image on the photosensitive member formed with the electrostatic latent image, and a transfer device to transfer the visible image formed on the photosensitive member onto a printing medium. The image forming unit includes a developing agent storage vessel to store a developing agent therein, a developing unit having a conductive layer to which the developing agent is attached and used to attach the developing agent to the photosensitive member, and a supply unit to supply the developing agent stored in the developing agent storage vessel to the developing unit. The developing unit and the supply unit satisfy a relational expression 1.7?logSr/logDr?2.5, where Sr a volume resistance of the supply unit and Dr is a volume resistance of the developing unit.

Abstract: A developing device comprises: a housing that stores developer; a developing roll that is rotatably supported in the housing and has a developing region with a roughened surface that supplies developer to an image region of an image holding member; a step portion that is formed at both sides of the developing region of the developing roll and whose diameter is smaller than that of the developing region; and a seal member that contacts a region of the step portion that is opposite to the image 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 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: A drum unit (20) for forming a toner image includes a cylindrical-shaped metal tubular member (31), a flange member (40) attached to one end of the metal tubular member (31) and a ground plate (50) attached to the flange member (40) and having an outer peripheral edge formed with a connection claw (52) that is so bent by the inner peripheral surface of the metal tubular member (31) as to bite into the inner peripheral surface for establishment of electrical conduction between the metal tubular member (31) and the ground plate (50). The flange member (40) has an edge, and the bending of the connection claw is carried out about a support point (412) defined by the edge. A calculational bending angle (?) at which the connection claw (52) is bent about the support point (412) is set in the range of 10 to 45 degrees.

Abstract: A development apparatus includes a first base member which bears and conveys a developer and which develops an electrostatic image in a first developing region, a restriction member which restricts a layer thickness of the developer borne by the first basemember, and a second base member which bears and conveys the developer received from the first basemember, and which develops the electrostatic image in a second developing region, the first base member is made of pure aluminum or aluminum alloy, and the second base member is made of stainless steel.

Abstract: A conductive rubber roller 10 has a conductive rubber layer 1, containing chloroprene rubber, and composes an outermost layer thereof. When an alternating current is applied to the conductive rubber roller 10 at a voltage of five and a frequency of 100 Hertz, the dielectric loss tangent is 0.1 to 1.8.

Abstract: A developing device including a developing roller facing an image bearing member and a toner layer thickness control member to control an amount of a toner adhered to the developing roller, so that an electrostatic latent image formed on the image bearing member is developed with the toner to form a toner image. The following relationships are satisfied: 0.08×100.3×Dv<Ra<0.18×100.3×Dv, 2.0<(Ra/RSm)×100<4.0, and 8<Rz<15, where Dv (?m) is a volume average particle diameter of the toner, Ra (?m) is an arithmetical mean roughness of the developing roller in a longitudinal direction, Rz (?m) is a ten-point mean roughness of the developing roller in a longitudinal direction, and RSm (?m) is a mean length of roughness curve elements of the developing roller.

Abstract: A contact pressure setting method of setting a contact pressure between contact members of an image forming apparatus. A film member is inserted into a gap between the contact members and the contact pressure is set so that a pulling force to pull out the film member lies within a predetermined range. Thus, the contact pressure can be accurately and easily recognized and the contact pressure can be set to be uniform.

Abstract: A thermal processor including a rotating drum including an internal heater configured to heat and maintain the drum at a desired set-point temperature, and a plurality of pressure rollers, including a first pressure roller, circumferentially spaced along a segment of the drum. A temperature sensor is configured to provide a temperature signal indicative of a temperature proximate to the first pressure roller. A controller is configured to adjust the desired set-point temperature based on the temperature signal.

Abstract: The invention relates to a novel covering layer for electrophotographic printing rollers with improved scratch resistance. Said covering layer consists of between 50 and 75 wt. % of cycloaliphatic epoxides, between 20 and 60 wt. % of aminofunctional silica nanoparticles, and between 0 and 2 wt. % of perfluoroalkyltrialkoxysilanes. The aminofunctional nanoparticles are produced from aminoalkyltrialkoxysilanes preferably by means of sol/gel technology.

Abstract: A developing device is provided to suppress image density unevenness by adjusting conditions of toner adhesion to an amorphous silicon photoconductor to a suitable range even when using both an amorphous silicon photoconductor and a nonmagnetic monocomponent toner and practicing development in a non-contact system. The developing device satisfies the relational expression: (f×1.5/?)2>?1.576×10?2×q/m×(Vpp/Ds2)+31.9×106 where Ds (m) is a distance between the photoconductor and the toner carrier, f (Hz) is a frequency of an AC bias applied to the toner carrier, Vpp (V) is an amplitude of the AC bias, ? (?) is a ratio of a peripheral speed of the toner carrier to a peripheral speed of the amorphous silicon photoconductor, and q/m (C/kg) is a charge quantity per unit mass of the toner.

Abstract: An image forming apparatus including: an image bearing member; and a developer bearing member bearing a developer including a toner and a carrier, the developer bearing member developing an electrostatic image formed on the image bearing member with the developer, and the developer bearing member being applied with an alternate voltage in order to form an alternate electric field between the developer bearing member and the image bearing member, wherein assuming that electric field intensities Eb and Ed be Eb=|(Vp1?VL)/D| and Ed=|(Vp2?VL)/D|, a relationship, 0?K1>K2, is satisfied, where K1: a gradient at Ed, and K2: a gradient at Eb, and wherein a resistivity ?b of the carrier at the electric field intensity Eb satisfies 1.1×106×en<?b<6.0×107 [?·m] (where: e is the base of natural logarithms; and n=4×Eb×10?7).

Abstract: Disclosed is a toner containing resin mother particles and oil, in which the volume-average particle diameter of the resin mother particles is not less than 2 ?m but less than 4 ?m, (volume-average particle diameter of the resin mother particles)/(number-average particle diameter of the resin mother particles) is more than 1 but less than 1.1, the oil is silicone oil or fluorine oil, and the content of the silicone oil or fluorine oil is not less than 0.05% by mass but less than 2% by mass relative to the resin mother particles.

Abstract: In order to obtain the surface shape which is uniform in each of the circumferential direction and the axial direction without being deviated in one direction on the surface, a developer holding body is provided which is arranged so as to face an image holding body, holds a developer as a layer onto a roughened surface, and supplies the developer in order to develop an image which is formed on the image holding body, and wherein the roughening is executed on the basis of a ratio of cutting depths in a plurality of directions.

Abstract: A device including a charging component; a developing component; a transport component; a photoconductive component; and a radiant fusing component; wherein the development component contains a toner comprising at least one crystalline polymer, optionally an amorphous polymer, and at least one colorant.

Abstract: An object of the present invention is to provide a toner for development of an electrostatic latent image, which has excellent developability and which is used in an electrophotographic image forming apparatus. One aspect of the present invention pertains to a toner for development of an electrostatic latent image, comprising cylindrical toner particles and titanium oxide particles added externally to the cylindrical toner particles, wherein the titanium oxide particles have an average primary particle size within a range from 10 to 100 nm, and the titanium oxide particles have a specific volume resistivity value within a specific range. Such a toner for development of an electrostatic latent image suppresses an image deletion phenomenon and is excellent in charge characteristics, and also exerts an extremely excellent effect on long-term printing durability.

Abstract: The present invention is intended to provide an image forming apparatus capable of producing high-quality images for a long period of time wherein the consumption of the opposite polarity particles is reduced, and a reduction in the amount of toner charge resulting from carrier deterioration is minimized, even if a great number of images having a low image area ratio were printed. This image forming apparatus is characterized in that the surface of an image carrying member, which is placed face to face with a toner carrying member, and on which an electrostatic latent image to be developed with the toner supported on the toner carrying member is formed, has an contact angle of 95 degrees or more with respect to pure water.

Abstract: A developing roller on a circumferential surface of which toner is held includes a plurality of first grooves formed in parallel to each other at approximately equal intervals, each in a direction inclined to a circumferential direction of the circumferential surface of the developing roller; a plurality of second grooves formed in parallel to each other at approximately equal intervals, each in a direction inclined to the circumferential direction of the circumferential surface of the developing roller, each second groove intersecting each first groove, the first groove and the second groove each having a U-shaped cross section; and a protrusion portion disposed in an area surrounded by the first groove and the second groove. In the developing roller, the protrusion portion has on a top surface thereof a plurality of minute projections, and when a surface roughness Rz of the top surface is RO, RO is 0.