Developer cartridge, developing device and image forming apparatus

A developer cartridge detachably mounted to a main apparatus, said developer cartridge comprising:

• a storage portion in which a developer is stored;
• an ejection opening that ejects said developer from said storage portion;
• and
• a first opening-and-closing member that opens and closes said ejection opening, said first opening-and-closing member including an engaging section that engages a to-be-engaged section of a second opening-and-closing member of said main apparatus;
• wherein said first opening-and-closing member is slidable to:
• a first position where said first opening-and-closing member opens said ejection opening and causes said developer cartridge to be fixed to said main apparatus;
• a second position where said first opening-and-closing member closes said ejection opening and makes said developer cartridge detachable from said main apparatus;
• and
• a third position where said first opening-and-closing member closes said ejection opening and causes said developer cartridge to be fixed to said main apparatus;
• wherein when said first opening-and-closing member moves from said first position toward said second position, said engaging section engages said to-be-engaged section to cause said first opening-and-closing member and said second opening-and-closing member to move together;
• and
• wherein when said first opening-and-closing member moves from said second position toward said third position, said engaging section releases engagement with said to-be-engaged section to cause said first opening-and-closing member to move without causing said second opening-and-closing member to move.