Developing apparatus including protruding portion overlapping discharge port

A developing apparatus comprising:

• a developer bearing member configured to bear and convey developer containing toner and carrier to develop an electrostatic image formed on an image bearing member;
• a developer container including a first chamber and a second chamber separated from the first chamber by a partition wall, the developer container being configured to contain the developer to be supplied to the developer bearing member;
• a first conveyance screw arranged in the first chamber, the first conveyance screw including a rotation shaft, a first blade member helically formed on an outer circumference surface of the rotation shaft and configured to convey the developer in a first direction, and a second blade member helically formed on the outer circumference surface of the rotation shaft and configured to convey the developer in a second direction being a direction opposite to the first direction;
• a second conveyance screw arranged in the second chamber, and configured to convey the developer in the second direction;
• a discharge path arranged outside a circulation path in which the developer circulates between the first chamber and the second chamber and connected to the first chamber to discharge the developer, the discharge path being provided with a discharge port arranged to oppose the rotation shaft and configured to discharge part of the developer conveyed in the discharge path from the discharge path in a direction intersecting with an axial direction of the rotation shaft;
• and
• a magnet,
• wherein the first conveyance screw further includes a third blade member arranged in the discharge path, helically formed on the outer circumference surface of the rotation shaft, and configured to convey the developer toward the discharge port,
• wherein the second blade member is provided between the first blade member and the third blade member in the axial direction of the rotation shaft,
• wherein the discharge port is arranged downstream of an upstream end of the third blade member in a developer conveyance direction of the third blade member,
• wherein the magnet is arranged downstream of an upstream end of the discharge port in the developer conveyance direction of the third blade member,
• wherein a protruding portion protruding in a radial direction of the rotation shaft is provided on the rotation shaft in an area located downstream of the third blade member and upstream of the magnet in the developer conveyance direction of the third blade member, the area overlapping the upstream end of the discharge port in the developer conveyance direction of the third blade member, and
• wherein the protruding portion overlaps the discharge port in the developer conveyance direction of the third blade member and includes a push-out surface configured to convey the developer in the radial direction of the rotation shaft by rotation of the first conveyance screw, the push-out surface being inclined such that, with respect to a plane orthogonal to a rotation direction of the first conveyance screw, one end of the push-out surface near the rotation shaft is located upstream of another end of the push-out surface near a leading end of the protruding portion in the rotation direction.