Image forming apparatus

Abstract

An image forming apparatus includes a movable image bearing drum; a device for forming a dot distribution electrostatic latent image on the drum in accordance with an image signal; a developing device for developing the dot distribution electrostatic latent image with a developer containing magnetic carrier particles and toner particles, the developing device including a rotatable developer carrying sleeve for carrying the developer to a developing zone, voltage source for applying an oscillating bias voltage to the sleeve, and a magnet stationarily disposed in the sleeve; wherein the magnet has first and second magnetic poles opposite polarities first magnetic pole being positioned upstream of a position where the drum and the sleeve are closest to each other and in an upstream part of the developing zone, the second magnetic pole is positioned downstream of the developing zone, wherein a downstream part of the developing zone include a region where an angle of magnetic line of force relative to a surface of the developer carrying member is not more than 15 degrees, and wherein the magnet is effective to contact chains of developer to the drum in the upstream part of the developing zone.

Dependencies are inferred from the claim text.