A developing device comprising:
- a first chamber configured to accommodate a developer including toner and a carrier;
- a first feeding screw provided in the first chamber and configured to feed the developer accommodated in the first chamber;
- a second chamber partitioned from the first chamber by a partition wall;
- a second feeding screw provided in the second chamber and configured to feed the developer accommodated in the second chamber;
- a first rotatable developing member to which the developer is supplied, the first rotatable developing member carrying and feeding 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 including a first magnetic pole provided opposed to the image bearing member in the developing position, a second magnetic pole provided downstream of the first magnetic pole with respect to 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 the same magnetic polarity as that of the second magnetic pole;
- a second rotatable member provided opposed to the first rotatable developing member and to which the developer is delivered from the first rotatable developing member by a magnetic field generated by the first magnet, the second rotatable member carrying and feeding the developer for collecting, in the second chamber, the developer after the electrostatic latent image is developed;
- a second magnet provided non-rotatably and stationarily inside the second rotatable member, the second magnet including a fourth magnetic pole having a magnetic polarity different 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 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 member, and having a magnetic polarity different 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 member, and having the same magnetic polarity as that of the sixth magnetic pole;
- and
- a guiding portion provided opposed to the second rotatable member and configured to guide the developer to the second feeding screw,
- wherein the first rotatable developing member and the second rotatable member rotate in the same direction in mutually opposing positions thereof,
- wherein the developer after the electrostatic latent image is developed is delivered from the first rotatable developing member to the second rotatable member by a magnetic field generated between the second magnetic pole and the fourth magnetic pole;
- and
- wherein in a case where
- a normal component of magnetic flux density in an arbitrary point on an outer peripheral surface of the second rotatable member opposing an inclined surface of the guiding portion is Br,
- a tangential component of the magnetic flux density in the arbitrary point is Bθ, and
- an angle Θ of a magnetic brush in the arbitrary point is arctan (Br/Bθ),
- with respect to the rotational direction of the second rotatable member, there is a portion where an absolute value of the angle Θ of the magnetic brush is 45° or more in a range from an intersection point, on the outer peripheral surface of the second rotatable member, which is a point where a rectilinear line passing through an end portion of the guiding portion on a side opposite from the second feeding screw and a rotation center of the second rotatable member crosses the outer peripheral surface of the second rotatable member, to a closest point, on the outer peripheral surface of the second rotatable member, which is a point where the outer peripheral surface of the second rotatable member is closest to the guiding portion.