To provide a liquid ink reinjection method to an ink cartridge that communicates with the atmosphere and at least includes a liquid remaining amount sensor, a differential pressure regulating valve and an air bubble trap, capable of inexpensively reinjecting liquid ink without causing wrong recognition of the liquid remaining amount sensor and damaging the differential pressure regulating valve.
A liquid ink reinjection method for a used ink cartridge includes: a first step of arranging a discharge port 5 of an ink cartridge 1 on the upper side, of disposing a cartridge surface having an ink discharge port horizontally to seal an atmosphere opening 6 and of making an injection port 7 installed in the middle of a flow passage to a liquid ink storage chamber communicating with the atmosphere have a negative pressure to inject the liquid ink from the injection port; and a second step of sucking the ink discharge port by changing the arrangement state of the ink cartridge at the first step to a state where the ink cartridge is rotated so that bending of the liquid ink flow passage faces upwardly, following the first step, and of moving the liquid ink injected at the first step to the ink discharge port side.
ISHIBASHI YOSHIO
ISHIZAWA TATSURO
TAGUCHI TETSUYA
