Abstract: To prevent deterioration of charge performance, which is caused by wear of a gap control member that keeps a charge roller into non-contact with the image carrier, the charge roller is brought into contact with a surface of a photosensitive drum via a pair of tape members as the gap control member that contacts with a coat and non-charge portion of the photosensitive drum. A gap G can be formed between an effective charge width portion of the charge roller and the surface of the photosensitive drum.

Abstract: An object of the present invention is to provide an image forming apparatus that has an image bearing body, a flexible charging member constituting a nip portion together with the image bearing body, the nip portion being provided with conductive particles, and a developing member for developing an electrostatic image formed on the image bearing body, with use of a developing agent, wherein the developing agent has substantially spherical toner.

Abstract: An image forming apparatus includes an endless image carrier belt configured to be spanned around a driving roller and a driven roller and moved by a friction force provided from an outer circumference surface of the driving roller when the driving roller is rotated, a charging device configured to contact an outer surface of the image carrier belt to charge the image carrier belt. The outer surface of the image carrier belt which the charging device contacts is a portion of the image carrier belt contacting the driving roller.

Abstract: An image forming apparatus includes an image bearing member for bearing an electrostatic image. A developing device develops the electrostatic image on the image bearing member by toners charged with a predetermined polarity. A transfer device transfers a toner image on the image bearing member to a transferring material. An electrifying device inject-charges the image bearing member having transfer residual toners. An electrical conductive member provided and spaced apart from the image bearing member in a moving direction of the image bearing member downstream farther than the transfer means and upstream farther than the electrifying device. An electrical field forming device for forming an alternative electrical field between the electrical conductive member and the image bearing member.

Abstract: In an image-forming apparatus having at least i) an electrophotographic photosensitive member having at least a photoconductive layer and a surface layer on a conductive substrate, ii) a developing means having a toner, and iii) a charging means, the photoconductive layer comprises a non-single-crystal material composed chiefly of silicon, the surface layer comprises a non-single-crystal carbon film containing at least hydrogen and has a dynamic hardness in the range of from 4.90×109 to 1.76×1010 Pa (500 to 1,800 kgf/mm2), the charging means has a charging member kept in contact with the electrophotographic photosensitive member, forming a contact zone therewith, charges the electrophotographic photosensitive member electrostatically upon application of a voltage, and the toner is a magnetic toner having toner particles containing at least a binder resin and a magnetic material, and an inorganic fine powder, having an average circularity of from 0.950 to 1.

Abstract: An image forming apparatus includes a plurality of image bearing members, a plurality of developing devices for developing latent images formed on the plurality of image bearing members with toners of plural colors, an intermediate transfer member to which toner images of plural colors are successively transferred from the plurality of image bearing members, the toner images of plural colors on the intermediate transfer member being transferred to a recording material, and a plurality of chargers for charging residual toners residual on the image bearing members after the toner images have been transferred from the image bearing members to the intermediate transfer member, the residual toners on the image bearing members charged by the chargers being electrostatically collected into the developing devices.

Abstract: An image forming apparatus includes an image bearing member; a charge member, contactable to the image bearing member, for electrically charging the image bearing member, the charge member being capable of being supplied with a voltage; developing means for developing an electrostatic image formed on the image bearing member with a developer; wherein the charge member is rotatable so as to provide a first peripheral speed difference between a surface of charge member and a surface of the image bearing member when the image bearing member is charged for image formation; wherein there is provided a cleaning period for transferring the developer from the charge member to the image bearing member with a second peripheral speed difference, which is smaller than the first peripheral speed difference, between the surface charge member of and surface of the image bearing member, when a charging operation for the image formation is not effected to the image bearing member.

Abstract: An electrophotographic photosensitive member is disclosed which has a photosensitive layer containing an organic charge-generating material and an organic charge-transporting material, and a surface layer containing electroconductive particles, and is charged electrically by a charging member placed in contact therewith. The photosensitive member has an electrostatic capacity of not less than 130 pF/cm2. Also, a process cartridge and an employing the photosensitive member are disclosed.

Abstract: In an image-forming apparatus having at least i) an electrophotographic photosensitive member having at least a photoconductive layer and a surface layer on a conductive substrate, ii) a developing means having a toner, and iii) a charging means, the photoconductive layer comprises a non-single-crystal material composed chiefly of silicon, the surface layer comprises a non-single-crystal carbon film containing at least hydrogen and has an arithmetic-mean roughness Ra ranging from 0 nm to 100 nm in an extent of 10 &mgr;m×10 &mgr;m of the surface layer, the charging mean is a magnetic-brush charging assembly or an elastic-roller charging assembly holding thereon a conductive fine powder, and the toner is a magnetic toner having toner particles containing at least a binder resin and a magnetic material, and an inorganic fine powder, having an average circularity of from 0.950 to 1.000, and having a saturation magnetization of from 10 to 50 Am2/kg (emu/g) under application of a magnetic field of 79.

Abstract: An image forming apparatus includes an image bearing member; charger for electrically charged said image bearing member; electrostatic image forming means for forming an electrostatic image by selectively discharging a surface of said image bearing member charged by said charger; developing means for developing the electrostatic image on said image bearing member into a toner image with toner; transfer means for transferring the toner image from said image bearing member onto a transfer material; wherein said charger is capable of collecting residual toner remaining on said image bearing member after image transfer operation by said transfer means; electric field forming means for forming an electric field between said charger and said image bearing member to transfer the toner in said charger to said image bearing member; and control means for controlling a length of time for which said electric field forming means forms the electric field.

Abstract: A process cartridge is disclosed which includes an electrophotographic photosensitive member having a photosensitive layer and a charging means. The charging means has a charging member which is provided in contact with the electrophotographic photosensitive member to charge the photosensitive member electrostatically by applying a voltage formed by superimposing an alternating-current voltage on a direct-current voltage. The photosensitive member has a surface layer which contains at least one of a polyarylate resin having a weight-average molecular weight of 7.5×103 to 3.7×104 and having a specific structural unit of Formula (1) and a polycarbonate resin having a weight-average molecular weight of 7.5×103 to 3.7×104 and having a specific structural unit of Formula (2). The photosensitive member further contains fluorine-containing resin particles. Also, an electrophotographic apparatus having the photosensitive member is disclosed.

Abstract: Magnetic particles for charging an image-bearing member electrostatically. The charging magnetic particles have magnetic particles, first surface coat layers containing a first surface coating agent and covering the surfaces of the magnetic particles and second surface coat layers containing a second surface coating agent and covering the first surface coat layers. The charging magnetic particles contain magnetic particles for charging which have a maximum chord length of 5 &mgr;m or larger, and the magnetic particles for charging which have a maximum chord length of 5 &mgr;m or larger having a minor-axis length/major-axis length standard deviation of 0.08 or more. Also, a process for producing the charging magnetic particles is disclosed together with a charging member, a process cartridge and an image forming apparatus which make use of the charging magnetic particles.

Abstract: A conducting member is disposed in contact with an electrophotographic photosensitive member to which a voltage is to be applied and includes a support and a coating layer formed on the support. The coating layer contains a conducting agent having been subjected to surface treatment and the surface of the conducting member has a coefficient of static friction of 1.0 or lower.

Abstract: A charging member has an electrically conductive base material and a surface layer including a foaming body of a continuous bubble material.

Abstract: A charging apparatus charges a moving body to be charged, which has a charging member for coming in contact with the body to be charged to charge the body to be charged, and contacting/separating device for contacting the charging member with and separating the charging member from the body to be charged, wherein the contacting/separating device converts a moving force of the body to be charged into a force for contacting/separating the charging member.

Abstract: An image forming apparatus including a photoreceptor having an image forming portion; a charging roller having a gap forming member on both ends thereof to form a gap between the photoreceptor and the charging roller and configured to charge the photoreceptor, wherein the gap forming members do not contact the image forming portion, and wherein the relationship t≧2g is satisfied; a light irradiator configured to form a latent image in the image forming portion; an image developer configured to form a toner image on the photoreceptor; and an image transferer configured to transfer the toner image onto a receiving material, wherein g is the gap and t represents a distance between an inside edge of one of the gap forming members and one of the two ends of the image forming portion closer to the inside edge of the gap forming member.

Abstract: A charging device or a transfer device used for an electrophotographic printer includes a charging unit. In this charging unit, a shaft is loosely encased by a conductive elastic cylinder. Further, the conductive elastic cylinder is loosely encased by a seamless charging tube. As to the charging device, the charging unit is pressed against a photosensitive drum. The seamless charging tube and the conductive elastic cylinder are driven to rotate in association with a rotation of the photo sensitive drum. A charging voltage is applied between the seamless charging tube and the photosensitive drum.

Abstract: The present invention relates to an image forming apparatus with a charging member which charges an image bearer with a photoconductive surface. Forming a layer containing ferroelectric as part on the charging member, and applying the electric field formed by dipoles of the ferroelectric, the photosensitive member surface is electrified, thereby downsizing a charger and reducing power consumption thereof are achieved for realizing low-cost and reducing the number of consumable parts sufficiently.

Abstract: An object of the present invention is to provide a process cartridge detachably mountable to a main body of an image forming apparatus, which has an image bearing member, a charging member for charging the image bearing member while the charging member is in contact with the image bearing member, and storage device for storing information concerning the type of the charging member.

Abstract: A charging apparatus includes a charging member arranged to be adjacent to a photoconductive member with a gap having a tolerance in a charging region relative to the photoconductive member and applied with a voltage including a direct current voltage under a constant voltage control including an alternating current element to apply a charge to the photoconductive member. The alternating current element has a peak-to-peak voltage at least twice as great as a charge-start voltage to be applied to the charging member at a maximum gap within a range of the gap having the tolerance.

Abstract: An image forming apparatus has an image bearing member, an electrifying device for electrifying the image bearing member, a transferring member provided with a contact portion contacting with the image bearing member, the transferring member causing the contact portion to make a transferring material pass it to thereby transfer a toner image formed on the image bearing member to the transferring material, the length of the transferring member in the lengthwise direction of the image bearing member being shorter than an electrification area in which the electrifying device electrifies the image bearing member, a cleaning blade contacting with the image bearing member to thereby remove any residual toner on the image bearing member, and lubricant imparting means for imparting a lubricant to at least the areas of the image bearing member in the lengthwise direction which are outside the transferring member and correspond to the end portions of the cleaning blade.

Abstract: A charging device is formed of a member to be charged, a charging member disposed so as to form a nip with the member to be charged, and electroconductive particles disposed so as to be present at the nip between the photosensitive member and the member to be charged. A uniform direct injection charging performance is realized by providing the charging member with a fine network-textured surface having concave cells giving a total cell edge perimeter per unit area of 15 mm/mm2 to 60 mm/mm2.

Abstract: An image forming apparatus includes an image bearing member; a charge member for electrically charging the image bearing member while contacting to the image bearing member: voltage applying means for applying an oscillating voltage including a component of AC voltage to the charge member; first detecting means for detecting an average of the AC current applied to the charge member from the voltage applying means; second detecting means for detection a value of the AC current corresponding to a peak of the AC voltage; and control means for effecting control such that when a detected current value of the detecting means is smaller than a first predetermined value, the detected current value of the first detecting means is at the first predetermined value, and when the detected current value of the first detecting means is larger than the first predetermined value, a current value of the second detecting means is at a second predetermined value.

Abstract: A process cartridge has an electrophotographic photosenstive member and a conducting member disposed in contact with the electrophotographic photosenstive member and to which a voltage is to be applied. The electrophotographic photosensitive member and conducting member are supported as one unit and are detachably mountable to the main body of an electrophotographic apparatus. The electrophotographic photosenstive member has a support, and provided thereon are a charge generation layer and a charge trasport layer in this order. The charge transport layer having a thickness of from 12 &mgr;m to 40 &mgr;m and the conducting member has a conductive support and a covering layer provided thereon. The time constant &tgr; of electric current of the conducting member is 0.1 second or shorter.

Abstract: In the charging device, a frequency f(Hz) is set so that a frequency f(Hz) of an AC voltage to be applied to a charging member and a movement rate v (mm/sec) of the surface of an image carrier satisfy f(Hz)≧40(1/mm)·v(mm/sec).

Abstract: An electrophotographic photosensitive member capable of exhibiting stable potential characteristics and image forming performances under wide ranges of environmental conditions, is formed of an electroconductive support, and an intermediate layer and a photosensitive layer disposed in this order on the electroconductive support. The intermediate layer comprises a thermosetting resin and an organometallic compound, which may comprise a polymerizate of a compound represented by formula (1) below: (RO)m—M—(L)n  (1), wherein R denotes an alkyl group; M denotes aluminum, titanium, zirconium, germanium or silicon; L denotes an organic group; m and n are integers of at least 0 giving m+n=3 in case of M being aluminum and m+n=4 in case of M being titanium, zirconium, germanium or silicon.

Abstract: An image forming apparatus including an image bearing member; a charge member contacted to the image bearing member to electrically charge the image bearing member; voltage applying means for applying to the charge member an oscillating voltage including an AC voltage component; first detecting means for detecting an AC current applied to the charge member from the voltage applying means; second detecting means for detecting the AC current corresponding to a peak or a neighborhood of the peak of the AC voltage; control means for effecting control such that current detected by the second detecting means is a predetermined level when the current detected by the first detecting means is within a predetermined range and such that current detected by the first detecting means is a predetermined level when the current detected by the first detecting means is outside the predetermined range.

Abstract: An OPC 2, a charger 9, a cleaner 10 for cleaning the charger 9, a holder 11 for holding the charger 9, a support frame 12 for supporting the holder 11, a pair of springs 13 and 14 and a driver 15 for driving the holder are accommodated in a single process cartridge 8. The cleaner 10 can be brought into contact with the charger 9 and separated from the same. The driver 15 moves the cleaner 10 between a position of contact at which the cleaner 10 is brought into contact with the charger 9 and a position of separation at which the cleaner 10 is separated from the charger 9.

Abstract: To prevent deterioration of charge performance, which is caused by wear of a gap control member that keeps a charge roller into non-contact with the image carrier, the charge roller is brought into contact with a surface of a photosensitive drum via a pair of tape members as the gap control member that contacts with a coat and non-charge portion of the photosensitive drum. A gap G can be formed between an effective charge width portion of the charge roller and the surface of the photosensitive drum.

Abstract: An image forming apparatus includes a voltage control circuit and a decision circuit. The voltage control circuit varies a voltage to be applied to a charge roller at preselected intervals in correspondence to the non-image area of a photoconductive element. A photosensor senses the reflection density of a particular control pattern formed on the drum 1 before and after the above voltage is varied. The voltage control circuit controls the voltage to be applied to the charge roller in accordance with a ratio between the resulting outputs of the photosensor. The decision circuit determines, at the start-up of the apparatus, whether or not to cause the voltage control circuit 31 to execute the voltage control in accordance with ambient temperature sensed by a temperature sensor. If the ambient temperature is higher than a reference temperature, the voltage control circuit is inhibited from executing the control.

Abstract: An object of the present invention is to provide an image forming apparatus that has an image bearing body, charging device, wherein the charging device includes charging particle being in friction contact with the image bearing body thereby charging the image bearing body, electrostatic image forming device, developing device, and transfer device, wherein a pressure of the transfer material to the image bearing body is not less than 1 g/cm and not more than 100 g/cm in line pressure.

Abstract: An electrophotographic photosensitive member is disclosed which has a photosensitive layer containing an organic charge-generating material and an organic charge-transporting material, and a surface layer containing electroconductive particles, and is charged electrically by a charging member placed in contact therewith. The photosensitive member has an electrostatic capacity of not less than 130 pF/cm2. Also, a process cartridge and an employing the photosensitive member are disclosed.

Abstract: An image forming apparatus comprising an image bearing member and electrostatic image forming means including electrification means which is disposed in contact with the above described image bearing member at an electrification location for injection electrification of the image bearing member, and configured to set a peripheral speed different between the above described electrification means and the above described image bearing member which is smaller when an area of the image bearing member to be an image forming area is at the above described electrification location than that when at least a portion of an area of the image bearing member to be a no-image forming area is at the electrification location.

Abstract: An image forming apparatus includes a movable image bearing member; charging means including a charge member for electrically charging the image bearing member with electroconductive particles between the charge member and the image bearing member; developing means for developing a latent image with toner mixed with electroconductive particles; wherein the latent image is formed on the image bearing member having been charged by the charging means, and a toner image provided by development of the latent image by the developing means is transferred onto a recording material; wherein the electroconductive particles mixed in the toner is carried by the image bearing member and is fed to between the charge member and the image bearing member; and a width A, measured in a direction perpendicular to a moving direction of the image bearing member, in which the electroconductive particle are present between the charge member and the image bearing member, a width B in which the developing means is capable of effecting

Abstract: An image forming apparatus capable of preventing contamination of a brush-roller charger with toner depositions includes a photoconductor, a brush-roller charger, an image development mechanism, an image transfer mechanism, a cleaning mechanism, a power supply mechanism, and a controller. The photoconductor carries an electrostatic latent image thereon. The brush-roller charger rotates in contact with the photoconductor and initializes a surface of the photoconductor by applying a charge thereto. The image development mechanism contacts the surface of the photoconductor and supplies toner to develop a toner image according to the electrostatic latent image on the surface of the photoconductor. The image transfer mechanism transfers the toner image from the photoconductor to a recording sheet. The cleaning mechanism cleans the surface of the photoconductor. The power supply mechanism supplies power to the brush-roller charger.

Abstract: A semiconductive member such as a semiconductive belt or a semiconductive roll used with an image formation apparatus has a portion formed of a thermoplastic elastomer composition comprising a thermoplastic resin 73 as a matrix and rubber particles 72 at least some of which have conductivity and at least some of which are cross-linked as domain.

Abstract: A charging apparatus for charging a member to be charged, the charging apparatus includes a charging member for electrically charging the member to be charged; and electroconductive particle supplying means for loosening electroconductive particles stored in the form of granules each comprising aggregated electroconductive particles and supplying the loosened electroconductive particles to the charging member.

Abstract: What is provided is an image forming apparatus in which a particle carrier is not contaminated with toner. The image forming apparatus comprises an image carrier for carrying a toner image, and charging means for charging the image carrier, the charging means having charged particles to be brought into contact with the image carrier and particle carrier carrying the charged particles and having a resin layer containing a conductive material on its surface.

Abstract: An image forming apparatus includes an image bearing member for carrying an electrostatic image, a contact charger for electrically charging the image bearing member while contacting to a surface of the image bearing member, the contact charger forming an oscillating electric field having a frequency of 100-600 Hz; a developer for developing the electrostatic image on the image bearing member with a developer comprising toner and a carrier having a volume resistivity value of 106-1010 &OHgr;.

Abstract: A contact charging device includes a charging roller and a power source, the charging roller having a conductive core, a conductive elastic layer and a coating layer and rotating as being in contact with a photoreceptor drum made up of a conductive body and a photoconductor, and the power source applying between the core and the body a bias voltage in which an ac voltage has been superimposed on a dc voltage. The charging roller and the photoreceptor drum form an oscillation system of a characteristic frequency fm which oscillates due to static adsorptive force. The characteristic frequency fm is calculated from each parameter of the oscillation system, and a frequency fac of a superimposed ac voltage or twice the value of the frequency fac is set to fall within a range of fac≦0.5 fm or fac≧1.5 fm so as to suppress both resonance of the oscillation system and relatively large oscillation when taking viscosity damping resistance into consideration.

Abstract: An electrophotographic apparatus includes an electrophotographic photosensitive member; a charger for charging the electrophotographic photosensitive member including a charging member supplied with a voltage and disposed in contact with the photosensitive member so as to form a nip with the photosensitive member to charge the photosensitive member; an exposure device; a developing device; and a transfer device. The photosensitive member includes a surface layer containing a charge-transporting material having an oxidation potential of 0.4-1.0 volt. Charging promoter particles are present at the nip between the photosensitive member and the charging member to injection-charge the photosensitive member. Because of the selection of the charge-transporting material and the presence of the charging promoter particles, the photosensitive member can be effectively injection-charged.

Abstract: A charge roller that includes a metal core, an elastic member configured wrapped around the metal core, and film members is disclosed. Each of the film members is wrapped around each end of the elastic member in a circumferential direction of the metal core such that at least a part of each of the film members exists at every position around the ends of the elastic member in an axial direction of the metal core. Portions of the film members do not overlap each other in an radial direction of the metal core.

Abstract: An image forming apparatus includes an image bearing member for bearing an electrostatic image; developing means for developing the electrostatic image on the image bearing member with toner electrically charged to a predetermined polarity; transfer means for transferring the toner image from the image bearing member to a transfer material; toner charging means for electrically charging residual toner remaining on the image bearing member to the same polarity as the predetermined polarity; and an image bearing member charging means for contacting to the image bearing member carrying the toner charged by the toner charging means to electrically charge the image bearing member to the same polarity as the predetermined polarity, the image bearing member charging means being effective to reduce a charge amount of the toner.

Abstract: An electrophotographic apparatus is provided which has an electrophotographic photosensitive member, a charging member maintained in contact with the photosensitive member and charging the same by receiving a voltage, an exposure device, a developing device and a transfer device. The photosensitive member has a support, a charge generating layer on the support, and plural layers on the charge generating layer. The outermost surface layer of the plural layers has the largest relative dielectric constant. With the electrophotographic apparatus, good contrast between dark potential and light potential is maintained even after a prolonged use of the apparatus, and sufficient image density and image quality are obtained. Also a process cartridge adapted for use in the electrophotographic apparatus is provided.

Abstract: An image forming apparatus includes a charge roller rotatable in contact with the surface of an image carrier to thereby charge the surface. The charged surface of the image carrier is exposed imagewise for forming a latent image. A developing device develops the latent image to thereby form a corresponding toner image. The toner image is transferred to a recording sheet. The charge roller is formed of a core and an elastic body affixed to the periphery of the core. Stearic acid to be added to rubber, which is the major component of the elastic body, is selected to be 1 wt % or less. An AC current value to be applied to the core is selected to be 1.1 mA or less. The image carrier is free from defective charging ascribable to impurities to deposit on the charge roller.

Abstract: A charging device, an image forming apparatus including the charging device, an image carrier unit including the charging device and a charging roller, which faces a body to be charged and is applied with a voltage, are disclosed. The charging roller includes a metallic core and an elastic member covering the core. Films are respectively wrapped around and adhered to the opposite end portions of the elastic member. Springs press the charging roller toward a body to be charged, causing the elastic member to deform due to compression. The maximum deformation of the films, which deform along the outer periphery of the elastic member, is selected to be smaller than the thickness of each film in the radial direction of the charge roller. A gap is therefore formed between the elastic member and the body to be charged. This prevents the portion of the elastic member, which corresponds to an image forming region, other than opposite end portions from contacting the surface of the body to be charged.

Abstract: A charging device comprises a conductor, which is in contact with a photoconductor, and a power source circuit, which applies a voltage to the conductor and electrically charges the photoconductor as to have a predetermined level of potential. The power source circuit includes a resistor having a predetermined level of resistance, and provides the conductor with a voltage through the resistor, thereby to stabilize the charged potential of the photoconductor.

Abstract: When electrostatic capacity Cf [F/m2] per unit area of an elastic member when an ac voltage of an arbitrary frequency f [Hz] is applied is given by Cf=C1k·(f/1000)−a, using electrostatic capacity C1k [F/m2] per unit area when an ac voltage of 1 kHz is applied and using a rate of change a, electrostatic capacity C of a micro-region of an elastic member per unit area is substituted with Cf per each frequency component which forms a voltage of a rectangular pulse equivalent to a voltage applied to a charge system. Then, the elastic member is made of such a material that the rate of change a falls within a range of a ≦−0.1544·log(C1k/C0) +0.0307, and further, within a range of a ≦−0.146·log(C1k/C0) −0.0688.

Abstract: A charging apparatus includes a movable charging member for being supplied with a voltage to charge a member to be charged, said charging member being provided with a flexible member for forming a nip with the member to be charged, wherein a speed difference is provided between surfaces of the member to be charged and said flexible member; electroconductive particles supplying means, having a foam member contactable to said charging member, for supplying electroconductive particles to said charging member to provide the nip with the electroconductive particles.

Abstract: An image forming apparatus for injection charging which uses charging accelerating particles in a charging nip portion to rotate an image bearing body and a charging roller at different velocities and applies a bias in image forming which is different from a bias applied in non-image forming to feed substantially only the charging accelerating particles in non-image forming, thereby it is possible to enhance a charging property and to provide a favorable image.