Patent ID: 7171145

Claim:
An image forming apparatus comprising: an image carrier configured to allow a latent image to be formed thereon; a hollow, cylindrical developer carrier provided with a plurality of stationary magnetic poles thereinside; and a metering member configured to limit an amount of a developer, which is made up of a toner and a magnetic carrier and is deposited on said developer carrier, to pass; wherein one of said plurality of magnetic poles comprises a doctor pole facing said metering member; and wherein a surface of said developer carrier on which the developer is deposited by a magnetic force of one of said plurality of magnetic poles is moved in a circumferential direction to conveyed said developer to a developing zone where said developer faces a surface of said image carrier via a metering position where said developer faces said metering member, causing said developer forming a magnet brush to contact said surface of said image carrier and develop a latent image formed on said surface of said image carrier in an electric field; said image forming apparatus further comprising stationary layer angle setting means for setting, assuming that a developer layer, staying at a position upstream of said metering member in a direction in which said developer carrier conveys the developer, consists of a stationary layer in which said developer is not replaced and a flowing layer in which said developer is replaced, that an angle between, as seen from an axis of said developer carrier, an upstream edge portion, in said direction, of an end portion of said metering member, which faces said developer carrier, and a position where an end of said stationary layer upstream of, but remote from said edge portion, in said direction is located is a stationary layer angle θd, and that an angle between, as seen from said axis of said developer carrier, said edge portion and a position where a doctor-upstream pole just upstream of said doctor pole in said direction is located is an inter-pole angle θ 1 , said stationary layer angle θd to be smaller relative to said inter-pole angle θ 1 .