Abstract: A developing device for an image forming apparatus includes a developing roller for conveying toner deposited thereon to a developing region where it faces a photoconductive element. A magnet brush roller conveys a two-ingredient type developer, which consists of toner and magnetic particles, deposited thereto to a toner supplying region where it faces the developing roller. In the toner supplying region, only the toner is supplied from the magnet brush roller to the developing roller. The distribution of the number of toner particles for an amount of charge differs from the developing roller to the magnet brush roller.

Abstract: An image forming apparatus includes a latent image bearing member to bear an electrostatic latent image, and a developer bearing member to bear a developer, in which the electrostatic latent image is formed on the latent image bearing member by first uniformly charging the latent image bearing member and then by performing an optical writing operation. The electrostatic latent image is visualized by supplying the developer borne on the developer bearing member to the latent image bearing member. A lubricant for reducing a friction coefficient of a surface of the latent image bearing member is supplied to the latent image bearing member and the lubricant has a charging polarity opposite to that of the developer. The friction coefficient of the latent image bearing member is maintained such that adhering of the developer to a background part of the latent image is prevented as a result of supplying the lubricant to the latent image bearing member.

Abstract: An image forming apparatus including a cylindrical image carrier configured to carry an electrostatic latent image while rotating, and a cylindrical developer carrier configured to bear a developer and supply the developer to the image carrier by contacting the image carrier at a nip while rotating, wherein the surface of the image carrier has a friction coefficient of from about 0.1 to about 0.4. The image carrier may be an endless belt.

Abstract: An image forming apparatus capable of collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning the toner to a developing unit for reuse in the form of an air-toner mixture is disclosed. A toner conveying device includes a screw pump and a hopper portion positioned upstream of the screw pump in the intended direction of toner conveyance. When the collected toner accumulating in the hopper portion reaches a preselected amount, the toner conveying device is caused to start and stop operating at a specific timing.

Abstract: In an electrophotographic image forming apparatus including a toner recycling mechanism, a collected toner conveying device is free from troubles particular to a conventional device using a screw pump and an air pump and conveying toner and air mixture via an elastic tubing, i.e., the wear of a stator due to aging and a decrease in the delivery pressure of the pump ascribable to the wear. A control device controls, based on the cumulative operation time, an operation of the screw pump and an operation of the air pump. This provides the toner conveying device with durability, reliability and simple construction while insuring toner conveyance and reducing cost.

Abstract: A screw pump for use in an image forming apparatus for conveying toner has a female screw type stator formed with a double pitch spiral groove in its inner periphery, and a male screw type rotor rotatably received in the stator. Assuming that the rotor has a sectional diameter of RA, and that the stator has a minimum inside diameter of S.MIN, the rotor and stator bite into each other such that a dimensional ratio of RA/S.MIN satisfies a relation of RA/S.MIN.ltoreq.1.04. A toner conveying device using such a screw pump and a toner filling system are also disclosed.

Abstract: In an image forming apparatus including a developing device storing a two-ingredient type or a one-ingredient type developer, a cleaning unit removes toner remaining on a photoconductive element after image formation. A toner conveying device conveys the toner collected by the cleaning unit to one or both of the developing unit and toner storing means. A powder pump includes a rotor and causes the rotor to rotate in order to move the collected toner in the axial direction of the rotor.

Abstract: Image forming equipment of the type supplying a toner to a developing device thereof by using a cartridge which is filled with a toner. The cartridge has a sealed opening and is brought to a toner supply position in the equipment without having the opening unsealed by the operator. Even when the cartridge is pulled out during the loading operation, the toner is not scattered about. A new cartridge for replacing a used empty cartridge is brought to the toner supply position without requiring the operator to remove the empty toner. During the replacement, the toner remaining on the walls of the empty cartridge is prevented from being sprinkled.

Abstract: Image forming apparatus having two identical toner handling units each functioning as a developing device when located in a developing position or as a cleaning device when located in a cleaning position. The image forming devices are alternately and repetitively set in the developing position and cleaning position.