Abstract: Disclosed is a charging apparatus usable with an image forming apparatus that includes a body to be charged; a housing to rotatably support the body to be charged, a charging member to charge a surface of the body to be charged to a predetermined electric potential, a cleaning member to clean foreign materials remaining on the surface of the body to be charged, and a cleaning member supporting bracket disposed in the housing to support the cleaning member and the charging member.

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: Provided is an image forming apparatus which includes a cylindrical image carrier, on which at least an electrostatic latent image is formed, and a charge roller for non-contact charging the image carrier with a predetermined charge gap, and applies at least an alternating current (AC) voltage to the charge roller to non-contact charge the image carrier, wherein a predetermined number of partition members for partitioning an internal space of the image carrier into a plurality of sub-spaces are arranged at a central position of an axial direction of the image carrier or in the vicinity of the central position of the axial direction of the image carrier, in the image carrier.

Abstract: A first bearing member and a second bearing member fit in a first side and a second side of a rotating shaft in the axial direction, respectively. The first bearing member is held by a supporting portion provided in a casing on a side corresponding to an emplacing member of an image carrier drum. The second bearing member is held by fitting in a fit-in portion from inside. A wall surface that regulates a charging roller in a longitudinal direction is formed on the second bearing member to protrude from a wall surface rotatably and pivotally supporting the charging roller.

Abstract: A photoconductor unit for forming a toner image in an image forming device is disclosed. The photoconductor unit comprises a photoconductor drum, a charge roller and a first charge roller wiper. The photoconductor drum receives toner particles for forming the toner image that is transferred onto a media sheet. The charge roller charges the photoconductor drum. A first charge roller wiper is disposed substantially parallel to path along which the charge roller moves between a working position and a storage position. The first charge roller wiper is configured to peripherally contact and clean the charge roller when the charge roller assumes a working position. A second charge roller wiper may be provided adjacent the storage position and disposed substantially perpendicular to the path along which the charge roller moves.

Abstract: A conductive member including a conductive supporting body (1), an electric resistance adjusting layer (2) formed on the conductive supporting body (1), and space holding members (3, 3) provided on opposite ends of the electric resistance adjusting layer (2), at least one engaging projection (50, 60,70, 80) being provided on one of the electric resistance adjusting layer (2) and each of the space holding members (3, 3), and an engaging opening (51, 61, 71, 81) in which the engaging projection is inserted being provided in the other of the electric resistance adjusting layer (2) and each of the space holding members (3, 3).

Abstract: A charging member has a surface layer. The surface layer contains a polysiloxane having a first unit, a second unit and a third unit each of which is represented by a specific formula. The ratio of the sum of the mole numbers of the first and second units to the sum of the mole numbers of the first to third units is in a specific range.

Abstract: A conductive member to be disposed so as to abut on an image carrier is provided. The conductive member includes an elongate conductive supporter, an electrical resistance adjusting layer formed on a circumferential surface of the supporter, and a pair of gap maintaining members provided respectively to the two ends of the adjusting layer. A gap with a certain clearance between an outer circumferential surface of the adjusting layer and an outer circumferential surface of the image carrier provided in parallel to the adjusting layer is formed. A stepped portion is formed in a joint section between the adjusting layer and each of the gap maintaining members with the joint section. An inclination is formed so as to be continuously inclined from the outer circumferential surface of each of the gap maintaining members to the outer circumferential surface of the adjusting layer in the stepped portion.

Abstract: A charging device and an image forming apparatus using the charging device. The charging device includes a charging member to uniformly charge a surface of a latent image bearing member in contact therewith, a charge bias application unit to apply a charge bias to the charging member, a conductive member to contact a surface of the charging member, and a different-valued bias application unit to apply a different-valued bias different from the charge bias to the conductive member. The image forming apparatus includes a latent image bearing member to bear a latent image, a latent image forming unit to form the latent image on the latent image bearing member, a development unit to develop the latent image with toner, and the charging device.

Abstract: Toner having spindle-shaped particles is used to form images in an image forming apparatus. Each spindle-shaped particle has a ratio of a length in a minor axis to a length in a major axis in a range from 0.5 to 0.8 and a ratio of a thickness to the length in the minor axis in a range from 0.7 to 1.0. A charging device applies an electric charge onto an electrostatic latent-image carrier of the image forming apparatus. The charging device includes a charging roller, a surface roughness of which is equal to or smaller than 10 micrometers.

Abstract: An electrophotographic photosensitive member rotatably supported in an image forming apparatus. The electrophotographic photosensitive member includes a substantially cylindrical body and a photosensitive layer formed thereon and having a latent image forming area. The photosensitive layer is, when incorporated in the image forming apparatus, pressed harder at a middle portion than at end portions in an axial direction of the latent image forming area, and a thickness at the middle portion is larger than at the end portions. The photosensitive layer may have a dynamic indentation hardness larger at the middle portion than at the end portions.

Abstract: A charging device, a process cartridge, and an image forming apparatus are provided. The charging device includes a charging roller configured to charge an image carrier and a cleaning roller configured to clean the charging roller while making contact with a surface of the charging roller. The charging device further includes a bearing member including a first portion configured to rotatably support a rotational shaft of the charging roller and a second portion configured to rotatably support a rotational shaft of the cleaning roller. The charging device also includes an elastic member provided outside of the second portion of the bearing member with respect to an axial direction of the rotational shaft of the cleaning roller such that the charging roller makes contact with the image carrier when the first portion of the bearing member is pressed by the elastic member.

Abstract: The present invention is generally directed to composite materials or charge rolls comprising a sleeved foam charge roll where the sleeve is interference-fit over the foam core, and methods of constructing them. The foam core can be made with an outer diameter larger than that of the sleeve inner diameter. The sleeve can be interference fit over the foam core to provide a functional charge roll. In some embodiments the charge roll can be used in an image forming apparatus including, but not limited to, an electrophotography system, an electrophotographic copying machine, and a laser printer.

Abstract: The present invention provides a charging member, a charging device, an image forming apparatus, and a process cartridge that minimize local unevenness in potential of a charged object resulting from soiling of the charging member with soiling microparticles or soiling aggregates, that do not cause image failure such as unevenness in image density and scumming, and that output good images through the life of the charging member. The charging member charges a surface of the object by receiving a voltage while being in contact with the object, and satisfies the condition that Rzjis?30 and Rsk?0, where Rzjis represents the ten-point average roughness of a surface of the charging member in contact with the object and Rsk represents the skewness of a roughness curve.

Abstract: The invention delivers a charging roller which is capable of preventing current leakage to a photoreceptor throughout life-time and which has a stable resistance value throughout life-time. The charging roller contains a metal core and a rubber layer formed on the core. The rubber layer is an epichlorohydrin-based rubber base material to which an electronic conductive agent and an ionic conductive agent are added. The rubber layer is subjected to surface processing by spraying the surface with a solution containing an isocyanate compound and heating. The amount of the electronic conductive agent added to the rubber base material is limited so that a volume resistivity when only the electronic conductive agent is added to the rubber base material is 1.46×106 ?·cm or greater. In addition, the amount of the added ionic conductive agent is increased so that a volume resistivity when the electronic conductive agent and the ionic conductive agent are added to the rubber base material is 1.93×106 ?·cm or less.

Abstract: A charging member is provided in which a toner, an additive for use in the toner, or the like is hard to adhere to the surface even under repeated use for a long time, and hence the charging and image output are made stable for a long time even if the charging member is used in the DC contact charging method. Also provided are a process cartridge and an electrophotographic apparatus having the charging member. The charging member includes a support, a conductive elastic layer formed on the support, and a surface layer formed on the conductive elastic layer, characterized in that the surface layer contains a polysiloxane having a fluoroalkyl group and an oxyalkylene group, and a process cartridge and an electrophotographic apparatus having the charging member.

Abstract: This invention is a conductive elastic roller (1) comprising a shaft member (2) and one or more elastic layers (3) disposed on an outside of the shaft member (2) in a radial direction, wherein at least one of the elastic layers (3) is composed of an ultraviolet-curing type resin formed by curing a raw material for the elastic layer comprising a urethane acrylate oligomer (A), a photo-polymerization initiator (B) and a conductive agent (C) through ultraviolet irradiation, and the urethane acrylate oligomer (A) is a urethane acrylate oligomer synthesized by using as a polyol a polyether polyol (a1) having a proportion of primary hydroxyl groups in hydroxyl groups located at molecular ends of not less than 40% obtained by an addition polymerization of propylene oxide to a polyhydric alcohol alone, or the polyether polyol (a1) and another polyol (a2), and provides a conductive elastic roller (1) provided with an elastic layer having a low hardness, a small compression residual strain and an improved stain resista

Abstract: An image forming apparatus charges the surface of a photosensitive member to a predetermined potential. A current detector detects a charging current when the charging bias is applied. A storage stores a target charging current value when the photosensitive member is charged to a required potential. A usage acquiring portion acquires information relating to usage of the charging roller. A bias corrector performs first and second corrections. The first correction compares a charging current value with a stored target charging current value and determines a new charging bias based on the comparison. The second correction determines whether usage of the charging roller is a predetermined first amount or a greater amount based on acquired usage information, and when the usage is the greater amount, changes the target charging current value in accordance with the usage amount and obtains a new charging bias based on the changed target charging current value.

Abstract: A charger includes: a charging brush which is rotatably provided and is brought into contact with an image carrier to charge the surface of the image carrier; a charging roller which is brought into contact with the image carrier at a portion on the downstream side relative to the charging brush in the rotational direction of the image carrier to charge the surface of the image carrier; and a controller which controls voltages applied to the charging brush and charging roller, wherein the controller controls voltages applied to the charging brush and charging roller such that one-fifth of the absolute value of a charging brush current flowing between the image carrier and charging brush is lower than the absolute value of a charging roller current flowing between the image carrier and charging roller.

Abstract: An image forming unit is provided with a regulating member placed in such a way as to surround a charging roller to regulate movement thereof. The regulating member has a pressing section inclined with respect to a straight line connecting the center of the charging roller to the axis of the photoconductor, as seen from the axial direction of the photoconductor. The pressing section is inclined farther away from the photoconductor toward upstream of rotation of the photoconductor. The regulating member allows the charging roller to electrically charge the photoconductor with a simplified structure and prevents adhering substances from accumulating on the contact portion between the photoconductor and the charging roller.

Abstract: An image forming apparatus includes a plurality of image forming stations. In each image forming station an electrostatic latent image carrier and a charging member are arranged to face each other with a specified gap therebetween. A charging failure caused by an abnormal discharge in the gap is detected based on a current detection result by a current sensor, and an image forming station having an abnormality is reliably specified.

Abstract: The present invention relates to an electrophotographic photosensitive member and an image forming apparatus provided with the same. The electrophotographic photosensitive member includes a substantially cylindrical body and a photosensitive layer having a latent image forming area formed on the body. The photosensitive layer includes a first end in the axial direction of the latent image forming area and a second end located opposite to the first end in the axial direction. The first end is pressed harder than the second end. In the photosensitive layer, thickness or dynamic indentation hardness at the first end at one side of the latent image forming area is larger than thickness or dynamic indentation hardness at the second end located opposite to the first end in the axial direction of the latent image forming area.

Abstract: A contact angle of water on the surface of a charging roller is equal to or smaller than a contact angle of water on the surface of the photo conductor. This structure prevents slip of the charging roller in an image forming apparatus wherein the charging roller is rotated due to the driving force of the photo conductor which is transmitted from the photo conductor as the charging roller comes in contact with the surface of the photo conductor.

Abstract: A charging member is provided in which a minute gap between an image support body and the charging member is set widely but even so the charging member does not abnormally discharge easily, the charging member includes a conductive support body 903, an electrical resistance adjustment layer 902 disposed on the conductive support body 903 and a surface layer 901 disposed on the electrical resistance adjustment layer 902 in which the surface layer contains at least (a) polyol resin grafted with fluorine or silicon, (b) polyether polyol resin, (c) organic anion salt that contains fluorine and alkali metal or alkali earth metal and (d) polyisocyanate.

Abstract: An apparatus for charging an image transfer surface in an image transfer device includes a support member and a conductive polymer material surrounding an outer periphery of the support member. An inner portion of the conductive polymer material is loaded with a supplemental conducting agent, and an outer portion of the conductive polymer material is substantially free of the supplemental conducting agent.

Abstract: A conductive member, including a long conductive supporting body, an electrical resistance adjusting layer, disposed on the outer circumferential surface of the conductive supporting body and having a reduced diameter section at either end, and a pair of gap maintaining members which are respectively fitted onto said reduced diameter sections of the electrical resistance adjusting layer. The outer circumferential surfaces of the gap maintaining members have a height differential with respect to the outer circumferential surface of the electrical resistance adjusting layer, in such a manner that when abutted against an image carrier, a prescribed gap is formed between the outer circumferential surface of the image carrier and the outer circumferential surface of the electrical resistance adjusting layer. An interval between the end faces of the electrical resistance adjusting layer and the faces of the gap maintaining members opposing the end faces satisfies a predetermined relationship.

Abstract: An image forming apparatus includes an image bearing member, a charging roller and a pair of gap forming members. The image bearing member has a photoconductive surface including an image forming area for bearing an electrostatic latent image. The charging roller has a circular cross section with a first radius and a metallic core having a rotational axis of the charging roller, in parallel with and close to the image bearing member, and a charging surface for charging the photoconductive surface. The pair of gap forming members form a gap at least between the image forming area and the charging surface. Each of the pair of gap forming members have a circular cross section with a second radius such that a ratio of the second radius to the first radius is substantially constant through a whole rotational phase of the charging roller.

Abstract: A charging unit is disclosed capable of reducing undue variation and fluctuation margin of a charging gap, and controlling accurately the proper gap durably over the change of environmental conditions, which is suitably incorporated into an image forming apparatus. The charging unit is configured to charge an image bearing member in a non-contact arrangement, including a charging roller provided with a core shaft, a charging member formed of electroconductive resin integrally disposed on the periphery of the core shaft, and gap holding members formed of insulating resin each disposed at respective ends of the charging member outside an image forming region. The control of the charging gap is feasible by either forming the gap with a charging member having such a materials condition as to satisfy the relation, |G30?G10|×5<G20, where G10, G20 and G30 are the gap averages at 10°, 20° and 30° C.

Abstract: A charging member is provided in which a toner, an additive for use in the toner, or the like is hard to adhere to the surface even under repeated use for a long time, and hence the charging and image output are made stable for a long time even if the charging member is used in the DC contact charging method. Also provided are a process cartridge and an electrophotographic apparatus having the charging member. The charging member includes a support, a conductive elastic layer formed on the support, and a surface layer formed on the conductive elastic layer, characterized in that the surface layer contains a polysiloxane having a fluoroalkyl group and an oxyalkylene group, and a process cartridge and an electrophotographic apparatus having the charging member.

Abstract: An image forming apparatus includes a plurality of image forming units arranged in parallel, each image forming unit having an image carrying member and a charging roller disposed face to face with the image carrying member for electrically charging the image carrying member, and a shifting mechanism for selectively shifting at least one charging roller between a first position where the charging roller is brought into contact with the corresponding image carrying member to electrically charge the image carrying member in contact manner and a second position where the charging roller is moved away from the corresponding image carrying member to electrically charge the image carrying member in non-contact manner.

Abstract: An apparatus includes an image bearing member for carrying an image; an intermediary transfer member for receiving the image; a primary transfer member for transfer of the image onto the intermediary transfer member in a primary transfer station; a secondary transfer member for transfer of the image onto a transfer material in a secondary transfer station; a first charging member for charging toner remaining in a region upstream of the primary transfer station and downstream of the secondary transfer station; and a second charging member for charging the toner remaining in a region upstream of the primary transfer station and downstream of the first charging member. The first charging member rubs a surface of, and the second charging member moves in contact with, the intermediary transfer member, to transfer the toner remaining on the intermediary transfer member to the image bearing member simultaneously with the primary transfer.

Abstract: An image forming apparatus uses a charging roller to charge the surface of a photosensitive member to a predetermined potential. A current detector detects charging current when the charging bias is applied. A bias corrector corrects the charging bias and a storage stores a target charging current value when the photosensitive member is charged to a required potential. The bias corrector performs two corrections. The first correction compares a charging current value with a stored target charging current value, and determines a new bias based on the comparison. The second correction determines whether the bias obtained by the first correction is at a predetermined level or a higher level, and when the corrected charging bias is at the higher level, changes the target charging current value in accordance with the corrected charging bias and obtains a new charging bias on the basis of the changed target charging current value.

Abstract: An image forming apparatus includes a rotatable image carrying member, on a surface of which an electrostatic latent image is formed, and a charging roll that is in contact with the image carrying member to charge the surface of the image carrying member to a prescribed potential. The charging roll has, in non-image forming areas in both end parts in an axial direction of the charging roll, large diameter parts having a larger outer diameter than an outer diameter of a center part of the charging roll, and small diameter parts having a smaller outer diameter than the outer diameter of the center part inside the large diameter parts in the axial direction. Differences in outer diameter of the large diameter part and the small diameter part from the outer diameter of the center part each is approximately 0.25% or less of the outer diameter of the center part.

Abstract: A charging roller including: a support; an elastic layer provided on the outer peripheral surface of the support, and having a ground-finished outer peripheral surface; and a surface layer formed to cover the outer peripheral surface of the elastic layer and that has a thickness of about 2 ?m to about 10 ?m from the outer peripheral surface of the elastic layer, and a proportion of water absorbed in the total of the elastic layer and the surface layer, after storage for 48 hours in an environment having a temperature of 10° C. and a humidity of 15% RH, and after storage for 48 hours in an environment having a temperature of 28° C. and a humidity of 85% RH, being about 2% to about 8% by weight, being about 2% to about 8% by weight.

Abstract: A charging roller, adapted to face an image carrier at a predetermined charging gap and charge the image carrier in a non-contact state, including: a conductive shaft, provided with a pair of annular concave portions formed on an outer circumferential surface at both ends thereof; a conductive layer, formed on the outer circumference surface at a center portion of the conductive shaft defined between the pair of concave portions; and an insulating layer, formed on the outer circumferential surface at outer portions of the conductive shaft from the pair of annular concave portions.

Abstract: An image forming apparatus includes a rotatable image carrier, a charging roll and a support member. The image carrier has a surface on which an electrostatic latent image is to be formed. The charging roll follows rotation of the image carrier. The charging roll charges the surface of the image carrier at a predetermined potential. The support member is in contact with the charging roll at a contact point. The contact point is on a downstream of a nip portion between the image carrier and the charging roll in a rotation direction of the charging roll. The contact point is on an upstream of a plane, which contains an axis line of the charging roll and is perpendicular to a plane defined by an axis line of the image carrier and the axis line of the charging roll.

Abstract: An image formation device includes an image-bearing body that rotates, a charging roller that contacts the image-bearing body and is rotated by the rotation of the image-bearing body, and charges the image-bearing body, a cleaning roller that contacts the charging roller and is rotated by the rotation of the charging roller, and cleans the charging roller, and a first auxiliary roller that is provided coaxially with the charging roller, contacts the image-bearing body and is rotated by the rotation of the image-bearing body. The image formation device satisfies the following relation: F1>F2>F3 where F1 represents a friction force between the first auxiliary roller and the image-bearing body, F2 represents a friction force between the image-bearing body and the charging roller and F3 represents a friction force between the charging roller and the cleaning roller.

Abstract: A charging roller cleaning device is provided for removing impurities attached on a charging roller that charges a photosensitive medium to a uniform electric potential. Such a cleaning device includes: a cleaning roller arranged to rotate, while contacting the charging roller to remove the impurities attached on the charging roller; and a cleaning member arranged to scrap off impurities attached on the cleaning roller.

Abstract: A conductive member includes a conductive support and an electrical resistance adjusting layer formed on the conductive support. The electrical resistance adjusting layer includes a thermoplastic resin, a polymeric ion conductive material, and a graft copolymer which is compatible with both of the thermoplastic resin and the polymeric ion conductive material. The electrical resistance adjusting layer is formed in a sea-island structure formed from a sea portion made of the polymeric ion conductive material and island portions made of the thermoplastic resin, the island portions being dispersed in the sea portion and each of the island portions is formed in an elongate shape. A layer made of the graft copolymer is formed at boundaries between the thermoplastic resin and the polymeric ion conductive material.

Abstract: A proximity charger roller is disposed in proximity to a surface of an image carrier and uniformly charges an effective charging area of the image carrier. Abutting portions abut on the image carrier at its both edges which are located on the outer side of the effective charging area, thereby maintaining the proximity distance between the circumferential surface of the proximity charger roller and the image carrier constant. A cleaning roller is longer than the spacing between the abutting portions which are at the both edges, abuts on the abutting portions which are at the both edges, and presses with predetermined pressing force in the direction of the image carrier. The surface of the cleaning roller is made of a soft material and cleans a surface area between the two abutting portions of the proximity charger roller.

Abstract: A charging member, which can be provided in a process cartridge and/or in an image forming apparatus, includes a conductive supporting member, an electrical resistance control layer formed on an outer circumferential surface of the conductive supporting member, and a nonconductive gap retaining member configured to retain a gap between the conductive supporting member and an image carrying member closely disposed to each other to have a constant distance. At least a portion of the nonconductive gap retaining member is mounted on the electrical resistance control layer at both ends of the conductive supporting member, and a circumference of the nonconductive gap retaining member projects from the electrical resistance control layer. An amount of projection of the gap retaining member from the electrical resistance control layer decreases as the gap retaining member tapers in a direction toward a center of an image formation region.

Abstract: A charging member cleaning unit, that contacts a charging member that charges the surface of an image holding member provided in an image forming apparatus, and is used for cleaning the surface of that charging member, has an elastic layer, and has an amine content within the elastic layer of not more than approximately 60 ppm.

Abstract: An image forming apparatus has a latent image supporting body configured by a substrate and a covering layer provided on the substrate; and a charging device which is a rotating body configured by an axis member and a charging member provided on the axis member, and which charges the latent image supporting body facing the charging member. In this image forming apparatus, a value, which is obtained by dividing a capacitance [pF] between the axis member in the rotating body and the substrate in the latent image supporting body by the length [mm] in the direction perpendicular to the direction of the surface migration of the charging member, is set to be at least 0.35 [pF/mm], the capacitance being obtained when, instead of the latent image supporting body, the substrate in the latent image supporting body is caused to face the charging member.

Abstract: A conductive member includes, a conductive supporting body, an electric resistance-adjusting layer formed in the conductive supporting body, and a space holding member which is formed on each end of the electric resistance-adjusting layer and has a material different from a material of the electric resistance-adjusting layer, the space holding member constantly maintaining a space between an image carrier and the electric resistance-adjusting layer, and the electric resistance-adjusting layer including a resin composition having a thermoplastic resin (A) containing at least an ether group, a fibrous polymer (B), which do not melt in (A) and has an aromatic skeleton in a molecule, and an electrolyte salt (C).

Abstract: A charging unit available in a process unit detachably attached to an image forming apparatus includes a charging member configured to uniformly charge a surface of an image carrying member while contacting the image carrying member, and a charge bias applying unit configured to apply a charge bias superimposing a direct current voltage on an alternating current voltage to the charging member. The alternating current voltage satisfies a relational expression of “Vpp×0.4/t?8.8×103”, “Vpp” representing a peak-to-peak voltage of the alternating current voltage in the charge bias, and “t” representing a time period from a first point of a swing of a wave component starting to swing by a large amount to a same polarity as the direct current voltage of the charge bias to a second point of the swing of the wave component reaching approximately 80% of an amplitude of the wave component.

Abstract: A charging roller is provided. The charging roller is configured to face an image carrier at a predetermined charging gap and charge the image carrier in a non-contact state. A conductive shaft is provided with a pair of annular concave portions formed on an outer circumferential surface at both ends thereof. A conductive layer is formed on the outer circumference surface at a center portion of the conductive shaft defined between the pair of concave portions. An insulating layer is formed on the outer circumferential surface at outer portions of the conductive shaft from the pair of annular concave portions. A depth of the concave portions is larger than a thickness of the conductive layer.

Abstract: An electrophotographic imaging device includes a charging device, a cleaning device, and a fuser member that each include hydrophobic carbon nanotubes. The use of hydrophobic carbon nanotubes can increases the charging device's, the cleaning device's, and the fuser member's durability, conductivity, and contaminants deposition.

Abstract: An image forming apparatus includes a photoreceptor having on a surface thereof a photosensitive layer, in which an electrostatic latent image is formed, a contact charging roll applied with a bias containing a direct current component having superimposed thereon an alternating current component, the contact charging roll charging the photoreceptor to a predetermined potential, a film thickness detecting unit detecting a film thickness of the photosensitive layer of the photoreceptor, an environment detecting unit detecting environment, and a contact area changing unit changing a contact area between the contact charging roll and the photoreceptor based on detected results of the film thickness detecting unit and the environment detecting unit.

Abstract: An image-forming method employing an electrophotographic process is provided with which images having high resolution can be obtained and which is less apt to cause image defects even in repetitions of use, does not cause conspicuous image defects even under severe conditions suitable for high resolution, and has excellent electrical characteristics. The object has been accomplished with an electrophotographic photoreceptor for developing an electrostatic latent image formed in the surface thereof with a polymerization toner, the electrophotographic photoreceptor comprising a photosensitive layer which contains a polymer comprising a repeating unit including a partial structure represented by formula (1).

Abstract: An image forming apparatus has an organic photoconductor having a surface layer containing fluorine-containing resin particles whose number average primary particle size is not less than 0.02 ?m and is less than 0.20 ?m; a charging device to charge by bring an charging member in contact with the organic photoconductor; a latent image forming device to for a latent image on the organic photoconductor; a developing device to visualize the latent image with toner and to form a toner image on the organic photoconductor; and a transferring device to transfer the toner onto a transfer material.