To propose an ink feed system of an ink jet printer which has a good ink extraction efficiency when multicolor printing and monochrome printing are changed over.
In the ink feed system 10 of the ink jet printer 1, multicolor printing and monochrome printing are changed over by replacing an ink cartridge 20 to be fitted in a setting part 11. In the ink cartridge 20, a movable member 43 which partitions an ink storage chamber 45 from an atmosphere open side is moved by an ink suction force acted to an ink extraction opening 13b, and the inside of the ink storage chamber is maintained in a negative pressure state by a coil spring 44. When ink storage chambers 45 of a multicolor ink cartridge 20A are made to communicate with each other to constitute a monochrome ink cartridge 20B, ink flows into the ink storage chamber with no remaining ink from the other ink storage chamber, so that the ink extraction efficiency is improved.
Fujitsuna Hideyoshi
Osamu Suzawa