Patent ID: 7845784

Claim:
An ink supplying mechanism for an ink jet head for ejecting an ink while circulating the ink comprising: a circulating system comprising: an ink jet head having a nozzle, a pressure chamber fluidly communicating with the nozzle, and an upstream port and a downstream port that communicate with the pressure chamber; an upstream side tank that communicates with the ink jet head via the upstream port and stores an ink; a downstream side tank that communicates with the ink jet head via the downstream port and stores the ink; a circulating pump that feeds the ink from the downstream side tank to the upstream side tank; and a valve that opens and closes air of the downstream side tank with respect to atmospheric pressure; and a control device that is connected to the valve and the circulating pump and controls the circulating pump and an opening and closing operation of the valve, and that closes the valve and drives the circulating pump to make the liquid surface of the downstream side tank be a negative pressure, and feeds the ink from the downstream side tank to the upstream side tank via a feedback channel to circulate the ink.