Patent ID: 8424996

Claim:
An ink-jet printer which jets, onto a medium, liquid droplets of a plurality of color inks including black, cyan, yellow and magenta inks at a predetermined printing cycle, the printer comprising: a head which comprises: a plurality of nozzles formed corresponding to the plurality of color inks, respectively; a plurality of pressure chambers corresponding to the nozzles, respectively; and a channel which communicates the pressure chambers and the nozzles, respectively; a carriage which carries the head thereon and moves relative to the medium; and a control unit which controls the head so that during the predetermined printing cycle, the plurality of color inks are jetted in an order in which the black ink is jetted first or last among the color inks and the yellow ink is jetted after the cyan and magenta inks; wherein the control unit controls the head to jet the liquid droplets of the color inks at the predetermined printing cycle based on jetting timings, the control unit being configured to perform: a forming step for forming first images by jetting a first liquid droplet from a first nozzle corresponding to a first color ink a plurality of times at a plurality of first timings and jetting a corresponding second liquid droplet from a second nozzle corresponding to a second color ink a plurality of times at a plurality of second timings, while delaying the first and second timings with respect to each other by predetermined delay times so that the first images are formed to correspond to the delay times respectively; an evaluation step for performing evaluation of the first images; and a first extraction step for extracting, based on a result of the evaluation step, an optimum delay time, among the delay times, corresponding to an optimum first image among the first images; wherein the delay times include positive and negative values, as well as zero.