Print quality optimization for a color ink-jet printer by using a larger

Abstract

The diameter of nozzles in a nozzle plate used in ink-jet printer pens, or cartridges, for the black ink is set at a first value, e.g., 45 .mu.m, which is larger than that used for the color inks, e.g., 40 .mu.m. It has been found that merely changing the nozzle diameter is sufficient to change the ink droplet size. By designing the drop mass properly (i.e., lower than normal, with the volume of black ink at, for example 115 pl and the volume of color ink at, for example, 95 pl, as measured at room temperature), optimum print quality and reliability is achieved when the cartridge reaches steady state operating temperature in a printer provided with a heater to assist in drying the ink on the print medium. The inventive approach has several advantages over previous designs, including: (1) optimization/testing of the barriers and resistor topology is done only once for the cyan, yellow, magenta, and black cartridges; (2) operating energy in the printer is the same for the cyan, yellow, magenta, and black cartridges, thus simplifying the product design; and (3) manufacturing is greatly simplified, since the only part, other than the ink and some packaging, that is different between the black and color cartridges is the top nozzle plate.