Patent ID: 7909448
Filing Date: 2011-03-22
Classification: B41J,C09D

Abstract:
1. A recording unit comprising: (i) ink cartridges each having a single ink storage portion that stores a respective one of a plurality of inks constituting an ink set; and (ii) a recording head having ejection orifice lines each of which ejects a respective one of the plurality of inks, wherein each of the ink storage portions communicates with the atmosphere only through an ink supply opening, wherein at least three types of inks among the plurality of inks are different in specific gravity from one another, wherein at least two types of inks among the at least three types of inks are different in specific gravity by 0.020 or more, and wherein the arrangement of ejection orifice lines corresponds to an arrangement of the plurality of inks, and the plurality of the inks are arranged so that, among all arrangements of the inks, the arrangement of the inks is selected that has the smallest total sum of differences in specific gravities between the inks to be ejected from ejection orifice lines adjacent to each other among the plurality of inks to be ejected from the ejection orifice lines.