Developing device, image forming apparatus, and process cartridge

A developing device, comprising:

• a cylindrical and rotatable developer bearing member containing a magnetic field generator having multiple magnetic poles, the developer bearing member being disposed facing an electrostatic latent image bearing member to form a developing area therebetween;
• and
• a developer containing chamber containing a two-component developer comprising magnetic carrier particles having a saturated magnetization of 58 to 70 emu/g in a magnetic field of 1 KOe and toner particles, the developer containing chamber having a divider to define an upper supply chamber and a lower collection chamber,
• the supply chamber disposed on a substantially upper side of the developer bearing member, the supply chamber including a supply conveyer to supply the two-component developer to the developer bearing member at an upstream side from the developing area while conveying the two-component developer in an axial direction of the developer bearing member within the supply chamber,
• the collection chamber disposed on a substantially lower side of the developer bearing member, the collection chamber including a collection conveyer to collect the two-component developer from the developer bearing member at a downstream side from the developing area while conveying the two-component developer in the axial direction of the developer bearing member within the collection chamber,
• wherein the multiple magnetic poles includes three developer bearing poles capable of bearing the developer on its surface, the three developer bearing poles consisting of a developing pole, a pre-developing pole, and a post-developing pole,
• the developing pole generating a magnetic field in the developing area,
• the pre-developing pole generating a magnetic field that conveys the developer supplied from the supply chamber to the developing area, and
• the post-developing pole generating a magnetic field that separates the developer from the developer bearing member at a downstream side from the developing area and an upstream side from the developing pole.