Abstract: An image forming apparatus having: a plurality of photoreceptors provided along a sheet transportation path and each extending perpendicularly to the sheet transportation path; and an imaging mechanism for forming toner images on surfaces of the respective photoreceptors. A pair of support plates receive opposite end circumferential portions of the respective photoreceptors to support the photoreceptors together in a parallel relation. Bearings are fitted around the opposite end circumferential portions of the respective photoreceptors, and the pair of support plates each have the same number of cut-away portions as the number of the photoreceptors for receiving outer rings of the bearings, the cut-away portions being formed in a spaced apart relation.

Abstract: An image-forming machine which has an image-forming unit that moves substantially horizontally between an acting position in a housing and a non-acting position that is drawn out forward. The image-forming unit has a frame having a front wall member and a rear wall member, and a plurality of image-forming devices mounted on the frame. The front wall has a pair of receiving holes arranged at a distance in the transverse direction and the rear wall has a pair of pins located at a distance in the transverse direction. In a preferred embodiment, the housing has a pair of pins located in the front and a pair of receiving holds in the rear such that when the image-forming unit is brought to the acting position, the receiving holes of the front wall engage the front pins of the housing and the pins on the rear wall engage the receiving holes in the rear of the housing.

Abstract: An image-forming machine which forms an image on a photosensitive material drum which passes through the steps of electric charging, exposure to light, developing and transfer. A pair of side walls are disposed opposite to each other, spaced at a distance. Inner wheels of bearings have an inner wheel and an outer wheel. The inner wheels are secured to the outer peripheral surfaces of the photosensitive material drum at both ends thereof, and outer wheels of the bearings are secured to the corresponding side walls, so that the photosensitive material drum is rotatably supported by the side walls.

Abstract: An electrostatic copying machine made up of an image-forming unit including a rotary drum having an exposure zone and a transfer zone, an optical system for projecting the image of the document to be copied onto the exposure zone, a copying paper-feeding system including a paper-feeding cassette that can be freely drawn to the front surface of the body of the copying machine, and a copying paper conveying passage for conveying a copying paper fed from the copying paper-feeding means through the transfer zone. A fixing device and a pair of paper-discharging rollers are disposed on the downstream side of the transfer zone. The paper-feeding cassette, image-forming unit, fixing device and the pair of paper-discharging rollers are successively arranged from one side toward the other side in the body of the copying machine within the maximum exposure scanning length of the optical system, and the copying paper conveying passage is arranged substantially linearly.

Abstract: A developer unit of the present invention has an agitating paddle which agitates a developer containing a magnetic carrier and a non-magnetic toner, and a toner is supplied from the toner hopper according to an output of a toner concentration sensor. After an agitation is finished which is performed when the power is turned on, the agitating paddle is periodically operated to agitate the developer. During the agitation, a toner concentration controller shifts a reference level with which the output of the toner concentration sensor is compared from a predetermined level to a higher level and then stepwisely returns it to the predetermined level.