Toner cartridge attachable to developing unit and having toner discharge opening opened in response to the attachment

A toner cartridge comprising:

• a casing extending in a first direction and including a first toner-accommodating section having a first internal space configured to accommodating toner therein, the first toner-accommodating section including one end portion and another end portion in the first direction, the first toner-accommodating section having a first opening positioned at the one end portion, the first opening allowing toner in the first internal space to be discharged therethrough;
• a toner conveyance unit extending in the first direction and rotatable in a rotating direction about a first axis extending in the first direction, the toner conveyance unit being configured to convey toner from the first internal space to the first opening;
• a cover positioned at the one end portion of the first toner-accommodating section and covering the first opening, the cover having a second opening allowing toner in the first internal space to be discharged therethrough, the cover including a plurality of gear teeth positioned at a circumferential surface of the cover, the plurality of gear teeth being arrayed in the rotating direction, the plurality of gear teeth being positioned at one side of the second opening in the first direction and being configured to move a developing shutter of a developing unit for opening or closing an opening of the developing unit;
• and
• a first protrusion positioned opposite to the second opening with respect to the plurality of gear teeth in the first direction, the first protrusion being configured to release the developing shutter from a locking member of the developing unit, the locking member being configured to lock the developing shutter.