Patent ID: 7209681

Claim:
An electrophotographic apparatus comprising a plurality of image forming devices each comprising a photosensitive drum provided on a surface thereof with a photosensitive layer, a charging device for having the photosensitive layer charged at a predetermined electric potential, an exposure device for subjecting the photosensitive layer to exposure on the basis of image data to form an electrostatic latent image, and a developing device for adhering toner to the electrostatic latent image on the photosensitive drum to form a toner image, and wherein the plurality of image forming devices are arranged vertically along a straight portion of an endless intermediate transfer belt, which is stretched around a drive roller and a driven roller to revolve, or of a medium conveyance belt in such a manner that each photosensitive drum is in contact with an outer peripheral surface of the straight portion to transfer the toner image formed on the photosensitive drum through the intermediate transfer belt or directly to a medium to form a color image, and wherein each developing device comprises a tip end part and a toner storage part, coupled to the tip end part, to store toner, said tip end part comprising a developing roller in contact with the photosensitive drum to rotate to form a thin toner layer on a surface of the photosensitive drum, a supplying roller for supplying toner to the developing roller, and a toner regulatory blade brought into linear contact with an outer peripheral surface of the developing roller at a predetermined pressure to form a thin toner layer on the surface of the photosensitive drum, and wherein a thickness of the tip end part of each developing device in a direction of movement of the intermediate transfer belt or the medium conveyance belt is smaller than a thickness of the toner storage part in the direction of movement, and wherein each exposure device is arranged near the tip end part of each developing device, each exposure device comprising an LED array arranged in a widthwise direction of an associated photosensitive drum, and wherein a sum of thickness of the tip end part of the developing device and thickness of the toner storage part in the direction of movement of the intermediate transfer belt or the medium conveyance belt is at most 2 times a diameter of the photosensitive drum.