Patent ID: 7802878

Claim:
A liquid droplet ejection mechanism comprising: a first ink tank and a second ink tank which store ink; a plurality of ink chamber units which are capable of ejecting the ink; a first common flow channel which connects the first ink tank with the plurality of ink chamber units; and a second common flow channel which connects the second ink tank with the plurality of ink chamber units, wherein: each of the plurality of ink chamber units includes a pressure chamber which supplies the ink to a nozzle capable of ejecting ink, an ink supply channel which connects the first common flow channel and the pressure chamber, and an ink circulation channel which connects the second common flow channel and the pressure chamber; the ink supplied from the first ink tank circulates in such a manner that the ink flows through the first common flow channel, the ink chamber units that do not eject the ink, and the second common flow channel to the second ink tank to be recovered in the second ink tank; the plurality of ink chamber units include a nearest connection ink chamber unit which is connected to the first ink tank at the shortest distance from the first ink tank, of the plurality of ink chamber units, and is also connected to the second ink tank at the shortest distance from the second ink tank, of the plurality of ink chamber units; and taking pressure in the first ink tank to be P i , taking pressure in the second ink tank to be P o , taking volume of the ink circulated per unit time from the first ink tank to the second ink tank when the plurality of ink chamber units do not eject the ink to be U o , taking the ratio between volume of the ink supplied per unit time from the ink supply channel and volume of ink supplied per unit time from the ink circulation channel when the ink is being ejected from at least one of the ink chamber units to be α i :α o , taking total volume of the ink ejected per unit time from all of the ink chamber units which are ejecting ink to be Q, taking flow channel resistance from a connection section with the first ink tank to a connection section with the nearest connection ink chamber unit in the first common flow channel to be R i , taking the flow channel resistance from a connection section with the second ink tank to a connection section with the nearest connection ink chamber unit in the second common flow channel to be R o1 , taking flow channel resistance in the first common flow channel between mutually adjacent ink chamber units to be R 1 , taking the flow channel resistance in the second common flow channel between mutually adjacent ink chamber units to be R 2 , and taking the total number of ink chamber units to be Z, both following conditions are satisfied: { Pi−Ri ×(α i ×Q+U o )}≧{ P o −R o1 ×(α o ×Q−U o )}, and [ Pi−Ri ×(α i ×Q+U o )− R 1 ×( Z −1)×{(α 1 ×Q )/2+ U o /2}]≧[ P o −R o1 ×(α o ×Q−U o )− R 2 ×( Z −1)×{(α o ×Q )/2− U o /2}].