Patent ID: 7018013

Claim:
An ink jet head comprising: a plurality of pressure chambers arranged in parallel, each of which is defined by side walls and communicates with an ink supplying path, wherein the plurality of pressure chambers comprise a plurality of pressure chambers in a printing region and at least one pressure chamber in a non-printing region; an ejecting nozzle provided at one end of each of the pressure chambers in the printing region; pressure means for varying a capacity in each of the plurality of pressure chambers in accordance with a respective driving signal; a dummy nozzle provided at one end of said at least one pressure chamber in the non-printing region, said dummy nozzle having (i) a shape for preventing ink from being elected therefrom which includes an aperture area at an ink ejecting side thereof which is greater than an aperture area of the ejecting nozzle at an ink ejecting side thereof, and (ii) a flow impedance which is substantially the same as a flow impedance of the ejecting nozzle, said flow impedance varying in accordance with both an inertial resistance of ink in the nozzle and a viscosity resistance of ink in the nozzle; and head driving means that selectively varies the capacity in the pressure chambers in the printing region by applying respective driving signals to the pressure means, to eject ink from the ejecting nozzles; wherein when the head driving means varies the capacity in a pressure chamber of the plurality of pressure chambers in the printing region which is positioned at an end of the printing region, the head driving means simultaneously varies the capacity in a corresponding said at least one pressure chamber in the non-printing region by applying a driving signal to the pressure means.