Patent ID: 6682169
Filing Date: 2004-01-27
Classification: B41J

Abstract:
A printing method comprising the steps of:providing a print head having a plurality of single chromatic nozzle groups each consisting of plurality of nozzles that are arranged at nozzle pitch kÃ—D where k is an integer of at least 2 and D is a pitch of main scan lines, the plurality of single chromatic nozzle groups being configured to eject mutually different chromatic inks, and an achromatic nozzle group for ejecting achromatic ink, the achromatic nozzle group consisting of a greater number of nozzles that are arranged at nozzle pitch kÃ—D than each of the single chromatic nozzle groups; and printing images in a monochromatic area on a printing medium with the achromatic ink alone, and in a color area with the chromatic inks, the step of printing images comprising the steps of: (a) executing monochromatic mode printing by repeating a unit scan operation using all the nozzles of the achromatic nozzle group but without using the single chromatic nozzle groups, the unit scan operation consisting of k main scans and (kâˆ’1) sub-scans of a first feed amount, wherein the unit scan operation in the monochromatic mode printing is performed such that all dot positions in an achromatic unit band consisting of plural main scan lines without any gap therebetween are serviced by the achromatic nozzle group, and wherein a monochromatic mode sub-scan of a second feed amount is performed in each interval between each unit scan operations, and (b) executing color mode printing by repeating the unit scan operation using a specific achromatic nozzle group and the plurality of single chromatic nozzle groups while a color mode sub-scan of a third feed amount less than the second feed amount is performed in each interval between each unit scan operations, the specific achromatic nozzle group being part of the achromatic nozzle group, wherein the step (a) comprises: (a1) in a case that a lowermost main scan line of the achromatic unit band comes to be positioned within the color area when it is assumed that the monochromatic mode sub-scan and the unit scan operation are performed next, and also that the lowermost main scan line of the achromatic unit band comes to be positioned within the monochromatic area when it is assumed that the color mode sub-scan and the unit scan operation are performed, performing a sub-scan of a specific feed amount so that the lowermost main scan line of the achromatic unit band comes to a lower edge of the monochromatic area when the unit scan operation is performed after the sub-scan of the specific feed amount; performing the unit scan operation once, while forming dots in the monochromatic area using all nozzles of the achromatic nozzle group; and proceeding to the color mode printing.