Patent ID: 6966626

Claim:
Printing device which performs printing by ejecting ink droplets from a nozzle and depositing the ink droplets on a printing medium to form dots, comprising: a print head equipped with a plurality of nozzles for ejecting ink droplets of a same given color, the plurality of nozzles including a prior nozzle group and a posterior nozzle group along a direction of sub-scanning in order from a nozzle group that first reaches a point over the print medium during sub-scanning, the posterior nozzle group being provided over an area equal in width to that of the prior nozzle group in the direction of sub-scanning; a main scan drive unit for performing main scanning by moving at least one of the print head and the print medium; a sub-scan drive unit for performing the sub-scanning by moving at least one of the print head and the print medium in a direction intersecting a direction of the main scanning; and a control unit for controlling the print head, the main scan drive unit, and the sub scan drive unit; wherein the plurality of nozzles are arranged in the direction of sub-scanning at a nozzle pitch equivalent to a multiple k (k being an integer equal to 1 or greater) of a main scan line pitch; during the main scanning, the control unit performs first partial line recording using the prior nozzle group, wherein some of pixels among pixels included in main scan lines positioned facing nozzles of the prior nozzle group are targeted for dot recording, and second partial line recording using the posterior nozzle group, wherein those pixels among pixels included in main scan lines positioned facing nozzles of the posterior nozzle group and that have not previously had dots recorded thereon by the prior nozzle group in previous main scans are targeted for dot recording; the first and second partial line recording being performed in such a manner that a number N 1 (N 1 being a positive integer) of pixels are targeted for recording by nozzles of the prior nozzle group in the first partial line recording in a single main scan, a number N 3 (N 3 being a positive integer) of pixels are targeted for recording by nozzles of the posterior nozzle group in the second partial line recording in the single main scan, and the number N 1 is a different value from the number N 3 .