Abstract: For realizing a satisfactory and stable developing process, the charge state of a developer and the density of toner particles contained in the developer is kept constant in the developing process. A developing roller to be driven rotationally is provided in a developing tank containing a developer. The developer is sucked magnetically using the magnetic force of a magnet provided in a developing sleeve composing the developing roller. The developer is then fed into a developing area opposed to a photosensitive member, then collected into the developing tank after the developing process is ended. The magnet is composed of an odd number of magnetic poles; developing pole, feeding pole, magnetic force distribution adjusting pole, developer sucking pole, developer separating pole, auxiliary collecting pole, and collecting pole. Between the sucking pole and the developing pole, an even number of poles are disposed. Between the developing pole and the separating pole are disposed an even number of poles.

Abstract: A developing apparatus comprises a development housing containing developer and disposed opposite to a carrier for carrying a latent image, and a developing roller rotatably provided in the development housing and rotatively driven in a predetermined direction. The developer in the development housing is carried by the developing roller and the developer carried by the developing roller is applied to the carrier through an opening formed in the development housing. A rotation speed F.beta. of the developing roller is higher than a movement speed F.alpha. of the carrier. A gap .beta. between an opening downstream side wall portion of the development housing and the developing roller is greater than a gap .alpha. between the opening downstream side wall portion and the carrier.

Abstract: Impurities contained in a developer are captured and prevented from mixing into the developer again, thereby to avoid lowering of image quality due to the impurities. Such impurities include aggregates of the developer formed in a developing apparatus, insufficiently charged toner particles, defectively charged toner particles having an opposite polarity to a predetermined polarity, and defective carrier particles lacking in strength for being held by a developing magnet roller. A recess is provided between peaks of magnetism located in a lower portion of a developing magnet roller. The recess has an air pressure substantially equal to an air pressure (atmospheric pressure) in the developing apparatus, so that air in the developing apparatus and the recess does not flow only in one direction. Impurities contained in the developer circulating around the developing roller cannot be magnetically held in the lower half of the developing roller because of centrifugal force and gravity.

Abstract: The invention is characterized by efficiently and quickly loosening an aggregation of toner material formed in a toner cartridge. A toner cartridge has an L-shaped toner agitating member disposed in a main body thereof having a discharge port for feeding toner at the front surface of the main body. Since the toner agitating member is supported so as to pivot like a conical pendulum, a support pin fixed to a bottom surface of the main body passes through a through hole having a greater diameter than that of the support pin. The support pin has an engagement portion attached thereto for prevention of disengagement of the toner agitating member therefrom. A plate-like portion of the toner agitating member defines an agitating plate, a distal end of which extends toward the discharge port of the main body.

Abstract: Vents are formed on a developer flow regulating plate inside a casing so as to reduce a pressure in a first space which increases as a developer holder rotates. Further, vents for connecting a vacuum space formed in front of a developer layer thickness regulating section for regulating a thickness of a developer layer formed on the surface of the developer holder and the outside air are formed. The vents thus formed for connecting the vacuum space and the outside air take in the outside air along the front face of the developer layer regulating section so as to increase the negative pressure in the vacuum space. A shape of a lower edge portion of an opening section formed on the casing is varied in a longitudinal direction so as to optimize an effect of suppressing a scattering of a developer. Furthermore, a rotation start timing of an agitating section for agitating the developer to be supplied to the developer holder is delayed from a rotation start timing of the developer holder.