Patent ID: 7699452

Claim:
A method of injecting ink into an ink cartridge adapted to be mounted on an ink jet recording apparatus having a recording head, the method comprising: providing an ink cartridge comprising: a lower section ink chamber; an upper section ink chamber; an ink supply port adapted to supply ink to the recording head; an ink suction passage fluidly connecting the lower section ink chamber to the upper section ink chamber, and having an upper end opening disposed proximate a bottom of the upper section ink chamber and a lower end opening disposed proximate a bottom of the lower section ink chamber; an ink flow passage fluidly connecting the upper section ink chamber to the ink supply port; and a differential pressure valve having a membrane member, and disposed within the ink flow passage, the differential pressure valve being configured to selectively block ink flow from the upper section ink chamber to the ink supply port in accordance with a differential pressure between the ink supply port and the upper section ink chamber; reducing pressure in the ink cartridge though the ink supply port; and injecting ink into the lower section ink chamber and the upper section ink chamber such that a proportion of ink stored in the upper section ink chamber to a total volume of the upper section ink chamber is larger than that of ink stored in the lower section ink chamber to a total volume of the lower section ink chamber.