A developing apparatus comprising:
- a developing container including a first chamber configured to contain a developer including a toner and a carrier, and a second chamber partitioned from the first chamber by a partition wall;
- a first rotatable developing member to which the developer is supplied, the first rotatable developing member being configured to carry and feed the developer to a developing position where an electrostatic latent image formed on an image bearing member is developed;
- a first magnet provided non-rotatably and stationarily inside the first rotatable developing member, the first magnet having a first magnetic pole provided to face the image bearing member at the developing position, a second magnetic pole provided downstream of the first magnetic pole in a rotational direction of the first rotatable developing member, and a third magnetic pole provided downstream of the second magnetic pole and adjacent to the second magnetic pole, with respect to the rotational direction of the first rotatable developing member, and having a same magnetic polarity as that of the second magnetic pole;
- a second rotatable developing member disposed to face the first rotatable developing member and configured to receive the developer delivered from the first rotatable developing member by a magnetic field generated by the first magnet, the second rotatable developing member being configured to carry and feed the developer after developing the electrostatic latent image in the second chamber to collect the developer in the second chamber;
- a second magnet provided non-rotatably and stationarily inside the second rotatable developing member, the second magnet having a fourth magnetic pole having a different magnetic polarity from that of the second magnetic pole, a fifth magnetic pole provided downstream of the fourth magnetic pole with respect to a rotational direction of the second rotatable developing member, a sixth magnetic pole provided downstream of the fifth magnetic pole and adjacent to the fifth magnetic pole, with respect to the rotational direction of the second rotatable developing member, and having a different magnetic polarity from that of the fifth magnetic pole, and a seventh magnetic pole provided downstream of the sixth magnetic pole and adjacent to the sixth magnetic pole, with respect to the rotational direction of the second rotatable developing member, and having a same magnetic polarity as that of the sixth magnetic pole, wherein the developer after developing the electrostatic latent image is delivered from the first rotatable developing member to the second rotatable developing member by a magnetic field generated between the second magnetic pole and the fourth magnetic pole;
- and
- a duct including
- a suction port that is an inlet through which the developer scattered in the developing container is sucked, the suction port being disposed downstream, in the rotational direction of the second rotatable developing member, of a position at which the first rotatable developing member and the second rotatable developing member face each other,
- a first duct wall configured to extend downstream, in the rotational direction of the second rotatable developing member, of the suction port, the first duct wall disposed to face a part of the second rotatable developing member with a gap therebetween, and
- a second duct wall disposed to face the first duct wall and configured to form a space between the second duct wall and the first duct wall through which the developer sucked from the suction port flows, the second duct wall being positioned on an outer side than the first duct wall with respect to a rotation center of the second rotatable developing member in a direction from the rotation center of the second rotatable developing member toward a position on an outer peripheral surface of the second rotatable developing member where an absolute value of a normal component of a magnetic flux density of the sixth magnetic pole becomes maximum,
- wherein the rotational direction of the second rotatable developing member is opposite from the rotational direction of the first rotatable developing member at the position at which the first rotatable developing member and the second rotatable developing member face each other, and
- wherein the position on the outer peripheral surface of the second rotatable developing member where the absolute value of the normal component of the magnetic flux density of the sixth magnetic pole becomes maximum is positioned downstream of an edge of the first duct wall on the suction port side with respect to the rotational direction of the second rotatable developing member.