Patent ID: 7941081

Claim:
A developing unit for developing an electrostatic latent image formed on an outer peripheral surface of a latent image bearer rotating in one direction with an electrified developer that is prepared by mixing two components, or an electrostatically chargeable toner and magnetic carrier, comprising: a developing roller formed of a magnet roller incorporating a plurality of fixed magnetic pole elements and a cylindrical sleeve that rotates relative to the magnet roller for supplying the developer to the latent image bearer, by attracting the developer on the surface of the rotating cylindrical sleeve; and a carrier collecting roller disposed on the downstream side of the developing roller with respect to the rotational direction of the latent image bearer, characterized in that the carrier collecting roller includes only first and second magnetic pole elements having different magnetic polarities, both presenting a magnetic field intensity of 400 G to 750 G; the first magnetic pole element is disposed at a position on the opposite side across a center of the carrier collecting roller from a position opposing the latent image bearer; and the second magnetic pole element is disposed at a position opposing the developing roller.