Uninterrupted ink supply system

An uninterrupted ink supply system, comprising:

• a main cartridge, having a cavity for storing ink;
• a connection device, located on said main cartridge, and connecting said cavity inside said main cartridge to outside of said main cartridge, said connection device having a structure for automatic airflow control, and including:
• a connection base having a tube body at a top and a liquid air interface tube at a bottom, and being separated by a base plate, the connection base further having a central column extending along an axis inside said tube body and said liquid air interface tube, a lower end of said liquid air interface tube being lower than a lower end of said central column, an internal of said central column having an independent ink channel and an independent air channel, both said ink channel and said air channel flow through said central column, wherein after said connection device is installed to said main cartridge, lower ends of said liquid air interface tube, said ink channel and said air channel are all inside said cavity of the main cartridge;
• and
• a replenishment cartridge, connected to said connection device, and using gravity to facilitate ink inside said replenishment cartridge to continuously and automatically flow into said main cartridge, said automatic airflow control structure of said connection device automatically stopping ink flowing from said replenishment cartridge to said main cartridge when an ink level inside said main cartridge reaches a specific height.