Abstract: An image forming apparatus includes the first image forming section for forming color images, and the second image forming section for forming monochrome images, wherein the first image forming section is slidable through an opening formed on the front face of the main body, while the second image forming section is slidable through an opening formed on the side face of the main body so that the first and second image forming sections slide in mutually orthogonal directions. With this arrangement, various maintenance operations of each unit can be performed while suppressing a reduction in strength of the main body, whereby degradation of image quality with life can be avoided for a long period of time.

Abstract: Toner image forming means for forming toner images having chromatic colors of Y, M and C, respectively, are disposed on one side of an intermediate transfer belt, while disposing toner image forming means for forming a black toner image on the other side of the intermediate transfer belt, alone and on a most downstream side of all the toner image forming means. Further, when a toner image on the intermediate transfer belt includes toner having a reverse polarity, a transfer or developing process is controlled to reduce electrostatic attraction force acting on an image carrier, thus providing a color image forming device having a main body reduced in size and capable of faster image formation of a monochromatic image which is more frequently used, and of efficiently forming a color image by suppressing a back-transfer phenomenon and improving color reproducibility.

Abstract: An image forming apparatus includes the first image forming section for forming color images, and the second image forming section for forming monochrome images, wherein the first image forming section is slidable through an opening formed on the front face of the main body, while the second image forming section is slidable through an opening formed on the side face of the main body so that the first and second image forming sections slide in mutually orthogonal directions. With this arrangement, various maintenance operations of each unit can be performed while suppressing a reduction in strength of the main body, whereby degradation of image quality with life can be avoided for a long period of time.

Abstract: An image forming apparatus of the present invention includes a photoreceptor drum on which a toner image is formed, a transfer drum for transferring the toner image formed to transfer paper by bringing the transfer paper into contact with the photoreceptor drum, and a pair of register rollers for supplying the transfer paper to the transfer drum at a predetermined time and for curling the transfer paper in an arc. The register rollers include first and second rollers pressed against each other, the first roller being a predetermined hardness and the second roller being a hardness larger than the first roller. The transfer drum is disposed on the same side as the second roller with respect to an imaginary tangent line touching the surface of the second roller at one end of a contact section between the first and second rollers.

Abstract: An image forming apparatus having a main body whose upper section is split into first and second split lid sections. The first and second split lid sections are arranged to be freely opened and closed. A transfer body and a fixing device are detachably installed in the first split lid section, while a developing device and an image carrying body are installed in the second split lid section. The image carrying body and the transfer body are brought out of contact with each other by opening at least one of the first and second split lid sections. The transfer body and a fixing member are caused to be rotatable by opening the first lid section. With this structure, it is possible to easily repair a paper jam and perform maintenance of the respective sections without increasing the installation space.

Abstract: An image forming apparatus of the present invention includes a photoreceptor drum on which a toner image is formed, a transfer drum for transferring the toner image to paper by bringing the paper into contact with the photoreceptor drum, the transfer drum having a dielectric layer, a semi-conductive layer and a conductive layer laminated in this order from the paper side, a power source which is connected to the conductive layer so as to apply a predetermined voltage to the conductive layer, and a conductive roller for pressing the paper against a surface of the dielectric layer so as to produce a potential difference between the conductive layer and the paper. The potential difference induces charges of the same polarity as the voltage applied to the conductive layer on the surface of the dielectric layer, and charges of the opposite polarity on a back surface of the paper pressed against the surface of the dielectric layer.

Abstract: A charger performs corona discharge by applying a voltage to a discharging electrode. The charger includes an electrode plate formed in the shape of a panel on the discharging electrode, a plurality of projecting portions disposed in an end portion of the electrode plate, and a plurality of projection groups formed in each of the projecting portions such that the projection groups are adjacent to each other in a thickness direction of the electrode plate.

Abstract: A charger charges a recording medium before irradiation of light to form an electrostatic latent image by irradiating light as an optical image onto a surface of the recording medium. The charger includes a discharging electrode having a plurality of projections for generating corona discharge to charge the recording medium surface, a conductive shield case having an opening face opposite to the recording medium and opposed to the discharging electrode, a holding member for holding the discharging electrode in the shield case in a state in which the discharging electrode is electrically insulated from the shield case, a conductive grid electrode electrically insulated and held between the discharging electrode and the recording medium, and a power supplying device for supplying a high voltage for discharge to the discharging electrode and setting a ratio of electric currents flowing through the grid electrode and the shield case such that these electric currents are approximately equal to each other.

Abstract: An apparatus for the formation of images which includes two process-cartridges, one of which is a photosensitive cartridge including a photosensitive drum, a charger, a cleaning device, and the like, and the other of which is a developing cartridge including a developing device, a toner storage container, and a used toner collecting container; the developing cartridge being separated into a first cartridge including the developing device alone and a second cartridge including the toner storage container and the used toner collecting container, where the lifetime of the photosensitive cartridge is a first integer times the lifetime of the first cartridge, and the lifetime of the first cartridge is a second integer times the lifetime of the second cartridge, where each of the first and second integers is greater than one.

Abstract: An electrophotographic copying machine device provided with a pair of lens arrays installed in parallel to enable variable- or actual-size copying and a means for selectively directing the light-path, allowing each lens array to select its light-path before projecting the original image onto a recording medium such as a photoreceptive drum, in which the copying device incorporates the following: equalizing the distance between original-scanning starting points for actual- and variable-size copying to the distance between light-exposure positions on the recording medium by applying variable-size lens array; equalizing the distance between light-exposure positions on the recording medium, corresponding to the original-scanning starting point, and the image transfer starting position, by which image on the recording medium is transferred to the transference material using the variable-size lens array, to the distance for transferring the transference material from its standby position to its transference positio

Abstract: A photoreceptor cartridge unit having a cartridge frame made of plastic on which a photoreceptor drum acting as a rotary member and its peripheral components are integrally mounted. The cartridge frame is formed with a plurality of bearing portions for supporting the rotary members and a plurality of positioning projections and is split, at the bearing portions, into two frame portions provided with an engageable portion and a receiver portion, respectively. The peripheral components are formed with a plurality of positioning holes so as to be mounted on the cartridge frame through engagement of the positioning projections with the positioning holes. The two frame portions are coupled with each other through engagement of the engageable portion with the receiver portion.