Abstract: A charge roller of the present invention includes a shaft, an elastic member affixed to the circumference of the shaft, and a plurality of spacers affixed to the elastic member. Assume that rising portions formed, when the circumference of the elastic member is ground during production, at axially opposite end portions of the elastic member each have a width of W mm in the axial direction. Then, the spacers each are positioned at a distance of at least W/9 mm from the end of the elastic member toward the center in the axial direction.

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 including a plurality of image forming sections each having an electrostatic latent image bearing member to form a latent image on its surface, a charging device to uniformly charge the electrostatic latent image bearing member, a developing device to develop the electrostatic latent image formed on the electrostatic latent image bearing member into a visible image and a cleaning device to remove developer adhered to the electrostatic latent image bearing member. The image forming sections are disposed in series in close proximity to or contacting a transfer sheet conveying belt spanned rotatively and are configured to differentiate an amount of a lubricant to be supplied to the surface of each electrostatic latent image bearing member such that at least one image forming section is differentiated from other image forming sections.

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: 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: An image forming cartridge removably mounted on an image forming apparatus includes an image carrier for electrostatically forming a latent image thereon by electrophotography. A plurality of image forming members execute image formation with the image carrier. A casing accommodates the image carrier and image forming members. The image carrier has at least one axial end thereof supported such that it does not interfere with the casing. When the cartridge is mounted to the body of the image forming apparatus, a support portion for the image carrier and the casing are mounted to the body independently of each other.

Abstract: A developing unit of the present invention includes a developing roller facing a photoconductive element and formed with a magnetic layer on its circumference. The magnetic layer has a plurality of magnetic poles of opposite polarities alternating with each other and each extending in the axial direction of the developing roller. A developer consisting of magnetic particles an toner are deposited on the developing roller by the magnetic poles and conveyed by the roller to the photoconductive element carrying a latent image thereon, thereby developing the latent image. An agitator for agitating the magnetic particles and toner is positioned relative to the developing roller such that a blade thereof has an agitation range overlapping with the magnetic force range of the magnet layer. With this configuration, it is possible to insure high quality images free from background contamination and toner scattering while extending the service life of the developing unit.

Abstract: In an image forming apparatus, a developing device is disposed adjacent to a belt-like photosensitive member. A rotary type developing device has a hollow cylindrical casing rotatable around a shaft having a central portion for rotation. The developing device includes a casing which is rotated in a predetermined direction, and four partitions which divide the casing to make four developing units which extend radially outward from the shaft. A toner storing section or hopper is provided on one side of the developing device, i.e., on a front side of the image forming apparatus, and a toner cartridge is detachable from a top of the hopper, and the toner cartridge is exchanged when an end signal of the toner is detected by a sensor in the casing. The toner hopper is filled by new toner from the toner cartridge, and the toner is carried by conveyor members, which control an amount of the toner in the casing, and a supply roller supplies the toner to a developing roller.

Abstract: A developing device capable of obviating the cohesion of toner and reducing the amount of dead toner is disclosed. The device has a developing unit accommodating a first and a second screw therein. The first and second screws extend from the toner hopper to the other longitudinal end of the developing unit in parallel to a developing roller and a supply roller. The first screw feeds toner from a toner hopper to a developing section. The second screw collects toner not contributed to development from the developing section and returns it to the first screw for recirculation. In this configuration, the collected toner and dead toner aggregating in the lower portion of the developing unit are forcibly moved to the developing section. The direction in which the screw portion of the second screw is inclined may be partly reversed to form a reverse transfer portion. Alternatively, a part of a casing adjoining the hopper may be implemented as a slant.

Abstract: In an image forming apparatus, a rotary developing device effects development by revolving a plurality of developing sections around a rotary shaft until any one of them reaches a developing position where it faces an image carrier. Cartridges are respectively mounted to hoppers included in the developing sections. Guides are provided on the inner periphery of each cartridge in order to guide toner, moving due to the revolution or the developing device, toward a toner outlet formed in the cartridge. Even when the amount of toner remaining in the cartridge is small, the entire toner is replenished into the associated hopper and fully consumed.

Abstract: A rotary developing device for an image forming apparatus includes a plurality of rotary developing units accommodating a powder developer and being supported around a common axis, and a plurality of toner cartridges corresponding to the plurality of rotary developing units for supplying toner to the plurality of rotary developing units. Each rotary developing unit is moved to a developing position facing a latent image carrier by the rotation about the common axis and an electrostatic latent image formed on the latent image carrier is developed. The plurality of toner cartridges are connected with the plurality of rotary developing units so as to rotate together, and a toner outlet of the toner cartridge is disposed such that the toner is supplied to the respective rotary developing unit by the force of gravity on the toner accommodated in the respective toner cartridge at the time of rotational movement of the toner cartridge.

Abstract: A color image forming apparatus of the type having a photoconductive belt for forming a latent image thereon electrostatically. The latent image is developed to turn out a corresponding toner image. The toner image is transferred from the photoconductive belt to an intermediate transfer belt. Such a procedure is repeated to form a composite color image on the intermediate belt. The color image is transferred from the intermediate belt to a recording medium. Any point on the intermediate belt in the direction of rotation and any points on drive rollers assigned to the two belts, respectively, in the direction of rotation are held in the same positional relation to a stationary member every time the intermediate belt completes one rotation.

Abstract: In an image forming apparatus, a revolver type developing device has a plurality of developing units and revolves to sequentially bring them to a developing position facing an image carrier on which a latent image is electrostatically formed. The revolver promotes easy replacement and safe handling of the developing units and can be accurately positioned relative to the body of the image forming apparatus. Despite that the revolver is miniature, it prevents developers from leaking or flying off from the developing units and contaminating the inside of the apparatus or being mixed with each other.

Abstract: An electrophotographic color image forming apparatus is disclosed which allows a photoconductive element and an intermediate transfer belt, which are expendables, to be removed from the body thereof at the same time. This promotes easy replacement, inspection and so forth of expendables. The photoconductive element and intermediate transfer belt can be replaced substantially at the same period, reducing the frequency of replacement of expendables. A cartridge including the photoconductive element can be replaced with a minimum of component parts wasted, thereby enhancing the cost performance of the apparatus. Moreover, when a cover hinged to the body of the apparatus is opened, various units can be removed one after another, a unit around which the greatest space is available being first.

Abstract: A developing device for an image forming apparatus and using a one component type developer. The developer is transferred from a developer supply member to a developer carrier which are so rotated as to move in the same direction at a position where they contact each other. This prevents the developer from a toner storing section from directly reaching part of the developer carrier having moved away from the contact position despite the movement of the developer supply member. Conductive portions connected to ground and dielectric portions each having a small area are distributed regularly or irregularly on the surface of the developer carrier. Such a surface of the developer carrier is charged by friction by the developer supply member with the result that a great number of microfields are formed in the vicinity of the developer carrier. The microfields allow only the developer sufficiently charged by friction at the contact position to form multiple layers on the surface of the developer carrier.

Abstract: A developing device applicable to an electrophotographic copier, facsimile transceiver, laser printer or similar image forming apparatus and having a developing roller for carrying a nonmagnetic single component type developer, i.e., a toner and a toner supply roller for supplying the toner to the developing roller. The developing roller has dielectric portions and conductive portions each having a small area and distributed together on the surface thereof. The conductive portions are connected to ground and have a volume resistivity of 10.sup.6 .OMEGA.cm or below. The toner supply roller is made up of a metallic core and an elastic foam layer provided on the core and having conductivity and a predetermined frictional charging characteristic. A potential difference is set up between the developing roller and the toner supply roller to generate electric fields which act on a frictionally charged toner as a force directed from the toner supply roller toward the developing roller.