Patent ID: 8019250

Claim:
A developer cartridge comprising: an inner casing configured to accommodate toner therein, the inner casing having a circular cylindrical shape whose axis extends in an axial direction, the inner casing being formed with an inner opening, the inner casing having an outer peripheral surface defining a circumferential direction; an outer casing configured to accommodate the inner casing therein, the outer casing having a circular cylindrical shape and being formed with an outer opening, the outer casing and the inner casing being capable of rotating relative to each other between a first position where the inner opening and the outer opening are in communication with each other and a second position where the outer casing covers the inner opening; a sealing member provided on the outer peripheral surface of the inner casing and surrounding the inner opening, the sealing member being elastically deformable; an inner protrusion protruding from the outer peripheral surface of the inner casing toward the outer casing; an outer protrusion protruding from the outer casing toward the inner casing, and serving to maintain a prescribed gap between the inner casing and the outer casing, the outer protrusion being in separation from the inner protrusion in the circumferential direction at the first position, and the outer protrusion being in riding contact with the inner protrusion at the second position to displace the outer casing toward the inner opening and to elastically squash the sealing member between the inner casing and the outer casing in the second position.