Developing apparatus having multi-blade portion replenishment conveyance screw

A developing apparatus comprising:

• a developer bearing member configured to convey a developer containing toner and carrier to a developing position while bearing the developer,
• a developer container configured to accommodate the developer, the developer container comprising:
• a first chamber for supplying the developer to the developer bearing member;
• a second chamber partitioned from the first chamber by a partition wall;
• a first communication portion configured to allow the developer to be communicated from the first chamber to the second chamber;
• a second communication portion configured to allow the developer to be communicated from the second chamber to the first chamber;
• a replenishment conveyance path for conveying replenishment developer to a circulation path in which the developer is circulated between the first chamber and the second chamber;
• and
• a developer replenishment portion configured to supply the replenishment developer to the replenishment conveyance path;
• a first conveyance screw portion provided in the first chamber and configured to convey the developer in a first direction from the second communication portion toward the first communication portion;
• a second conveyance screw portion provided in the second chamber and configured to convey the developer in a second direction from the first communication portion toward the second communication portion;
• and
• a replenishment conveyance screw portion provided in the replenishment conveyance path and configured to convey the replenishment developer in a third direction from the developer replenishment portion toward the first communication portion,
• wherein the replenishment conveyance path is provided upstream of the second chamber with respect to the second direction,
• wherein the second conveyance screw portion is provided downstream of the first communication portion and upstream of the second communication portion with respect to the second direction,
• wherein the replenishment conveyance screw portion is provided upstream of the second conveyance screw portion with respect to the second direction,
• wherein a rotation shaft of the replenishment conveyance screw portion is coaxial to a rotation shaft of the second conveyance screw portion,
• wherein the replenishment conveyance screw portion comprises:
• a first blade portion formed in a spiral shape on an outer circumferential surface of the rotation shaft of the replenishment conveyance screw portion and configured to convey the replenishment developer in the third direction;
• a second blade portion formed in a spiral shape on the outer circumferential surface of the rotation shaft of the replenishment conveyance screw portion and configured to convey the replenishment developer in the third direction;
• and
• a third blade portion formed in a spiral shape on the outer circumferential surface of the rotation shaft of the replenishment conveyance screw portion and configured to convey the replenishment developer in the third direction,
• wherein a pitch of the first blade portion, a pitch of the second blade portion, and a pitch of the third blade portion are each larger than a pitch of a blade of the second conveyance screw portion, and
• wherein the third blade portion is continuously formed in a region between a terminal end of the first blade portion with respect to the third direction and a starting end of the second blade portion with respect to the third direction, the region being displaced in a circumferential direction of the replenishment conveyance screw portion from the terminal end of the first blade portion and the starting end of the second blade portion.