Patent ID: 7597434

Claim:
An ink-jet apparatus comprising: at least one ink jet head that includes a pressure chamber communicating with a nozzle and ejects ink communicating with the pressure chamber from the nozzle; a first pressure source that contains ink and generates, to the ink, “energy per unit volume” P 1 (Pa) that is based on static ink under atmospheric pressure at a height position of an opening of the nozzle; a second pressure source that contains ink and generates, to the ink, “energy per unit volume” P 2 Pa) that is based on static ink under atmospheric pressure at the height position of the opening of the nozzle, and control means, wherein the first pressure source, the pressure chamber, and the second pressure source are sequentially connected to a first channel and a second channel, and assuming that a proportion of a first channel resistance R 1 of the first channel from a branching point to the first pressure source to a second channel resistance R 2 of the second channel from the branching point to the second pressure source is “1:r” wherein r=R 2 /R 1 , the branching point branches from the first and second channels to the nozzle, the control means maintains the “energy per unit volume” P 2 (Pa) in a relationship of “P 2 ={(1+r)×Pn}−(r×P 1 )” for at least an ink-ejecting time from the nozzle, where the Pn is appropriate pressure of ink near the opening of the nozzle.