Developing apparatus

A developing apparatus comprising:

• a first rotatable developing member to which a developer including a toner and a carrier is supplied, the first rotatable developing member being configured to carry and feed the developer to a first developing position;
• a first magnet provided non-rotatably and stationarily inside the first rotatable developing member, the first magnet having a first magnetic pole and a second magnetic pole provided downstream of the first magnetic pole and adjacent to the first magnetic pole in a rotational direction of the first rotatable developing member and having the same magnetic polarity as that of the first 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 to a second developing position, the second rotatable developing member having a rotation axis positioned higher than a rotation axis of the first rotatable developing member in a vertical direction, the rotational direction of the first rotatable developing member at a first closest position where the first rotatable developing member is closest to the second rotatable developing member on an outer surface of the first rotatable developing member being opposite to a rotational direction of the second rotatable developing member at a second closest position where the second rotatable developing member is closest to the first rotatable developing member on an outer surface of the second rotatable developing member;
• and
• a second magnet provided non-rotatably and stationarily inside the second rotatable developing member, the second magnet having a third magnetic pole and a fourth magnetic pole, the third magnetic pole being disposed to face the first magnetic pole and having a different magnetic polarity from that of the first magnetic pole, and the fourth magnetic pole being provided downstream of the third magnetic pole and adjacent to the third magnetic pole in the rotational direction of the second rotatable developing member and having a different magnetic polarity from that of the third magnetic pole,
• wherein
• a first maximum position where a magnetic flux density of the first magnetic pole in a normal direction relative to an outer peripheral surface of the first rotatable developing member is maximum is positioned downstream of the first developing position and upstream of the first closest position in the rotational direction of the first rotatable developing member,
• a second maximum position where a magnetic flux density of the third magnetic pole in a normal direction relative to an outer peripheral surface of the second rotatable developing member is maximum is positioned downstream of the second closest position and upstream of the second developing position in the rotational direction of the second rotatable developing member,
• a third maximum position where a magnetic flux density of the fourth magnetic pole in the normal direction relative to the outer peripheral surface of the second rotatable developing member is maximum is positioned downstream of the second maximum position and upstream of the second developing position in the rotational direction of the second rotatable developing member,
• a relationship of r1×θ1 >r2×θ2 is satisfied, in a case where
• r1 represents a radius of the first rotatable developing member,
• r2 represents a radius of the second rotatable developing member,
• θ1 represents an angle from the first maximum position to the first closest position in the rotational direction of the first rotatable developing member, and
• θ2 represents an angle from the second closest position to the second maximum position in the rotational direction of the second rotatable developing member, and
• a relationship of r1×θ1<r2×θ3 is satisfied in a case where θ3 represents an angle from the second closest position to the third maximum position in the rotational direction of the second rotatable developing member.