Ink ribbon cassette and printing apparatus

An ink ribbon cassette comprising:

• an ink ribbon unit comprising an ink ribbon, a supply-side bobbin around which the ink ribbon before ink transfer is wound, and a wind-up side bobbin around which the ink ribbon after ink transfer is wound;
• and
• a case to house the ink ribbon wound around the supply-side bobbin and the ink ribbon wound around the wind-up side bobbin, wherein
• the case comprises:
• a case main body comprising a cylindrical supply-side case portion to house the ink ribbon wound around the supply-side bobbin and a cylindrical wind-up side case portion to house the ink ribbon wound around the wind-up side bobbin;
• and
• a cover removably attached to the case main body to close one end of the cylindrically formed supply-side case portion and one end of the cylindrically formed wind-up side case portion,
• the case main body is provided with a case-side engagement portion to fix the cover to the case main body,
• the cover comprises:
• a lock member provided with a cover-side engagement portion to engage with the case-side engagement portion;
• a cover main body to movably hold the lock member;
• and
• a bias member to bias the lock member to the cover main body,
• the lock member is movable with respect to the cover main body between a lock position where the case-side engagement portion engages with the cover-side engagement portion so that the cover is fixed to the case main body and an unlock position where an engagement state between the case-side engagement portion and the cover-side engagement portion is canceled so that the cover is removable from the case main body, and
• the bias member biases the lock member toward the lock position.