Abstract: In an electrophotographic image forming apparatus of the type including a plurality of image carriers arranged along an image transfer belt and an image transferring device configured to transfer toner images of different colors from the image carriers to a sheet being conveyed by an image transfer belt or by way of the image transfer belt by applying a bias to the belt, a bias applying method of the present invention can measure a current leaking between a plurality of high-tension power supply sections or to the ends thereof as AC resistances between respective terminals and therefore to accurately measure the leak currents of DC components. Therefore, when relatively high DC components are selected, a difference in current between a plurality of power supply sections can be maintained constant.

Abstract: An image forming apparatus of the present invention includes a cleaning device for cleaning an intermediate image transfer body. A cleaning blade included in the image transfer body is formed of fluorocarbon resin or a thin layer of fluorocarbon resin is formed on the surface of the intermediate image transfer body. Further, wax is coated on the intermediate image transfer body or wax or lubricant powder is contained in toner. A moving mechanism holds the cleaning blade spaced from the intermediate image transfer body at least when image formation is not under way.

Abstract: In an image formation apparatus, a voltage greater than a value, at which toner removal efficiency when a second cleaning device removes toner from an intermediate transfer body is maximum, is applied to a cleaning roller.

Abstract: An image forming apparatus including a belt guide member fixedly provided at an upstream side of a nip formed between a roller and a transfer roller so the belt guide member protrudes an image bearing belt such that the belt is substantially parallel with a conveying direction of a transfer medium.

Abstract: In an image formation apparatus, a voltage greater than a value, at which toner removal efficiency when a second cleaning device removes toner from an intermediate transfer body is maximum, is applied to a cleaning roller.

Abstract: An image transfer unit of an image formation apparatus is composed of a belt-shaped image bearing member on which a toner image is to be formed, a plurality of supporting and tension-application rollers which supports and provides tension to the belt-shaped image bearing member, an image transfer roller for transferring the toner image from the belt-shaped image bearing member to a transfer sheet, and a backup member having an outer peripheral elastic layer with a predetermined elasticity. The elastic layer of the backup member is urged with a predetermined pressure toward the image transfer roller via the belt-shaped image bearing member, with the belt-shaped image bearing member being held between the elastic layer of the backup member and the image transfer roller.

Abstract: A developing apparatus for an electrophotographic copier or the like includes a cylindrical developing sleeve which is rotatable to transport one component magnetic toner to a predetermined developing region where a photoconductive element is positioned. A magnet layer magnetized to have N and S poles which alternate with each other at a predetermined small distance is provided in the vicinity of the surface of the developing sleeve so as to deposit the toner on the magnetic layer. A blade is pressed against the surface of the magnet layer for frictionally charging the toner which is deposited on the magnet layer. A clearance is defined between the surface of the magnet layer and the blade and sequentially reduced in a direction of rotation of the sleeve, whereby the toner is charged and, at the same time, regulated into an even thin layer.

Abstract: A device for forming a toner film for use in developing an electrostatic latent image on an image bearing member, such as photosensitive member, is provided. A developing sleeve is rotatably provided and a magnet roll is also rotatably provided inside of the sleeve for magnetically attracting a blade of magnetic material to the outer peripheral surface of the sleeve thereby causing the toner carried on the sleeve to be formed into a film of desired thickness and charge. The magnet roll is formed with a plurality of magnetic poles elongated axially and arranged along the periphery of the roll in alternating polarities. Thus, the magnetic attractive force applied by the magnet roll to the blade changes periodically. In the present invention, the frequency of alternating magnetic field applied to the blade is set to be larger than the first order resonant frequency of the blade, thereby allowing to maintain the applied magnetic force as constant as possible.