Patent ID: 8995890
Filing Date: 2015-03-31
Classification: G03G

Abstract:
1. A developing device comprising: a developing member including a magnet member on which a plurality of magnetic poles including a developing main magnetic pole are arranged and magnetized in a circumferential direction, and a cylindrical developer holder that is disposed so as to face an image supporting member, receives the magnet member, and holds to transport a developer, wherein a distribution of a magnetic attraction force, which is applied on a peripheral surface of the developer holder in a developing area in a direction perpendicular to the peripheral surface by the magnet member, in a circumferential direction has a gradient that increases toward a downstream end from an upstream end of the developing area in a developer transport direction of the developer holder, and the plurality of magnetic poles are magnetized on the magnet member so that the amount of the increase of the magnetic attraction force between the upstream end of the developing area and a middle position of the developing area is larger than the amount of the increase of the magnetic attraction force between the middle position and the downstream end.