Developing device

A developing device comprising:

• a first chamber configured to accommodate a developer containing toner and a carrier;
• a first feeding screw provided in the first chamber and configured to feed the developer in the first chamber;
• a first rotatable member to which the developer is supplied from the first chamber and configured to carry and feed the developer for developing an electrostatic latent image formed on an image bearing member;
• a first magnet fixedly provided inside the first rotatable member and including a first magnetic pole and a second magnetic pole which is provided downstream of and adjacent to the first magnetic pole in a rotational direction of the first rotatable member and which is different in polarity from the first magnetic pole;
• a second rotatable member which is provided opposed to the first rotatable member, to which the developer is delivered from the first rotatable member by a magnetic field generated by the first magnet, and which is configured to carry and feed the developer for developing the electrostatic latent image, the second rotatable member having a rotation center R positioned above a rotation center Q of the first rotatable member in a vertical direction;
• a second magnet fixedly provided inside the second rotatable member and including a third magnetic pole which is provided opposed to the first magnetic pole and which is different in polarity from the first magnetic pole;
• a second chamber which is partitioned from the first chamber by a partition wall and in which the developer after the electrostatic latent image is developed with the developer is collected;
• and
• a second feeding screw provided in the second chamber and configured to feed the developer in the second chamber, the second feeding screw having a rotation center positioned above a rotation center of the first feeding screw in the vertical direction,
• wherein
• a point where a horizontal line L2 passing through the rotation center R of the second rotatable member and an outer peripheral surface of the second rotatable member intersect with each other and which is positioned on a side opposite from the image bearing member with respect to the rotation center R of the second rotatable member is a point P,
• a point where a vertical line passing through the point P and an outer peripheral surface of the first rotatable member intersect with each other and which is positioned above the rotation center Q of the first rotatable member in the vertical direction is a point X,
• a position where a magnetic flux density of the first magnetic pole in the normal direction relative to the outer peripheral surface of the first rotatable member becomes a peak is a point Y, and
• a position where a magnetic flux density of the second magnetic pole in the normal direction relative to the outer peripheral surface of the first rotatable member becomes a peak is a point Z,
• the point X is positioned downstream of the point Y and upstream of the point Z in the rotational direction of the first rotatable member, and
• wherein
• a rectilinear line connecting the rotation center Q of the first rotatable member and the point X is a rectilinear line L4,
• a rectilinear line connecting the rotation center Q of the first rotatable member and the point Y is a rectilinear line L5,
• a rectilinear line connecting the rotation center Q of the first rotatable member and the point Z is a rectilinear line L6,
• an acute angle formed between the rectilinear lines L4 and L5 is α [°],
• an acute angle formed between the rectilinear lines L4 and L6 is β [°], and
• α>β is satisfied.