Disc library storage system and disc cartridge used thereof

A disc library storage system, comprising:

• a disc library configured to accommodate a plurality of discs;
• a disc drive tower configured to accommodate a plurality of disc drives, wherein the disc drives are configured to read or write disc data;
• a disc transport device configured to move the discs to the disc drive tower from the disc library and to the disc library from the disc drive tower;
• and
• a disc changing device configured to place a disc cartridge, wherein the disc cartridge comprises an outer casing and a disc tray, the disc tray is configured to accommodate at least one replacement disc, and the disc changing device has a pull-out state and a close state;
• the disc changing device of the disc library storage system includes an ejection structure, wherein a bottom of the disc tray has at least one elastic buckle structure, and a bottom of the outer casing has at least one buckle opening;
• when the disc tray is received in the outer casing, the elastic buckle structure is buckled in the buckle opening;
• when the elastic buckle structure is pushed upwards by the ejection structure and detached from the buckle opening, the disc tray is drawn from the outer casing by the disc changing device,
• wherein, when the disc changing device is in the close state, the disc tray of the disc cartridge is drawn from the outer casing, and the disc transport device unloads the replacement disc from the disc tray,
• wherein, when the disc changing device is in the pull-out state, the disc tray of the disc cartridge is received in the outer casing.