Patent ID: 8684485

Claim:
A printing device comprising: a plurality of nozzle rows containing a nozzle row for chromatic ink and a nozzle row for achromatic ink, the nozzle row for chromatic ink having K nozzles for discharging chromatic ink arranged in a first direction (where K is an integer equal to or greater than 2), the nozzle row for achromatic ink having (nÂ·K) nozzles for discharging achromatic ink arranged in the first direction (where n is an integer equal to or greater than 2), and the nozzle rows being arranged along a second direction that intersects with the first direction; a movement mechanism configured and arranged to cause the nozzle rows to move relative to a print medium in a reciprocating manner along the second direction; a conveyance mechanism configured and arranged to convey the print medium relative to the nozzle rows along the first direction; and a control part configured to repeatedly perform an image-forming operation in which the nozzle rows discharge ink while the movement mechanism moves the nozzle rows in a forward direction and a reverse direction, and a conveying operation in which the conveyance mechanism conveys the print medium, thereby forming an image on the print medium, in a color region of the image in which the color region contains a chromatic color, the control part being configured to perform the image-forming operation m times (where m is an integer equal to or greater than 2 and equal to or less than n) in which the direction of movement of the nozzle rows switches alternately between the forward direction and the reverse direction, whereby a region of the image having a predetermined width is formed along the first direction, the image-forming operation performed m times including the image-forming operation performed once in which the direction of movement of the nozzle rows is a predetermined direction that is either one of the forward direction or the reverse direction and in which both of the nozzle row for chromatic ink and the nozzle row for achromatic ink are used, and the image-forming operation performed (mâˆ’1) times in which only the nozzle row for chromatic ink is used, and in a monochrome region of the image in which the monochrome region does not contain a chromatic color, the control part being configured to perform the image-forming operation once in which only the nozzle row for achromatic ink is used, whereby a region of the image having a predetermined width is formed, the control part being configured to change the direction of movement of the nozzle rows for performing the image-forming operation, in which only the nozzle row for achromatic ink is used, so that the predetermined direction is in the same direction for all color regions in the image.