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 member to which the developer is supplied, the first rotatable 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 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 with respect to a rotational direction of the first rotatable member, 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 member, and having a different magnetic polarity as that of the second magnetic pole, and a fourth magnetic pole provided downstream of the third magnetic pole and adjacent to the third magnetic pole, with respect to the rotational direction of the first rotatable member, and having a same magnetic polarity as that of the third magnetic pole;
- a second rotatable member disposed to face the first rotatable member and configured to receive the developer delivered from the first rotatable member by a magnetic field generated by the first magnet, the second rotatable member being configured to carry and feed the developer after developing the electrostatic latent image into the second chamber to collect the developer in the second chamber;
- a second magnet provided non-rotatably and stationarily inside the second rotatable member, the second magnet having a fifth magnetic pole having a different magnetic polarity as that of the third magnetic pole, wherein the developer after developing the electrostatic latent image is delivered from the first rotatable member to the second rotatable member by a magnetic field generated between the third magnetic pole and the fifth magnetic pole;
- and
- a duct portion including
- a suction port that is an inlet through which the developer scattered in the developing container is sucked, the duct portion being extended upstream, in the rotational direction of the second rotatable member, from the suction port,
- a first duct wall disposed to face the second rotatable member, and
- a second duct wall disposed to face the second rotatable member, and also disposed to face the first duct wall and configured to form a space through which the developer sucked from the suction port flows between the second duct wall and the first duct wall, 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 member in a radial direction of the second rotatable member,
- wherein, in a cross-section orthogonal to a rotational axis of the first rotatable member,
- in a state where an edge of the first duct wall on the suction port side, which is an end point on the second duct wall side, is referred to as a point A, a point on an outer surface of the first rotatable member where an absolute value of magnetic flux density of the second magnetic pole in a normal direction with respect to the outer surface of the first rotatable member is a maximum value is referred to as a point H, a straight line passing the point A and the point H is referred to as a straight line T, a straight line passing the point H and a rotation center O of the first rotatable member is referred to as a straight line L, and an angle formed by the straight line T and the straight line L is referred to as an angle θ, where θ is an acute angle,
- θ ≤ 60° is satisfied.