Patent ID: 8342666

Claim:
An ink-jet image forming apparatus comprising: a print head having a plurality of nozzles to eject ink; an ink tank to store the ink; an ink supply passage to supply the ink in the ink tank to the print head; an ink return passage to return the ink in the print head to the ink tank; a regulator mounted in the ink supply passage to regulate ink flow supplied to the print head; a shut-off valve including a valve seat having an orifice to connect to a passage at a side of the ink tank and a passage at a side of the regulator, an opening/closing member to open or close the orifice, the shut valve being mounted in the ink supply passage, between the ink tank and the regulator, to intercept ink flow supplied to the regulator; and an ink pump mounted in the ink return passage to forcedly flow the ink in the ink return passage, the ink pump being configured to be driven in forward and reverse directions to change an ink flow direction, wherein when the shut-off valve opens the ink supply passage and the ink pump is driven in the forward direction, the ink circulates between the print head and the ink tank, and wherein the shut-off valve closes when a purging operation of the print head is being performed.