Odd number of passes, odd number of advances, and

Abstract

A method of printing a desired color image on a printing medium by construction from individual ink drops deposited in pixel arrays includes passing a multiple-nozzle ink-discharging pen across the medium multiple times, each pass creating a portion of a respective segment of the image, and periodically advancing the medium so that the pen creates portions of successively different segments. During each pass, the 'portion-creating' function includes discharging from the pen an odd submultiple of the full density of ink desired in the segment of the desired image that is being created, so that printing full density in each segment requires an odd number of passes, preferably three. The medium is advanced by an odd submultiple of the height of the segment being created in each pass and is preferably advanced after each pass of the pen. For the preferred three passes, the odd submultiple of the height of the segment is preferably one-third. The portion-creating includes creation by the pen of a multiplicity of spaced-apart diagonal lines. Preferably in each passing step after a first one, the diagonal lines are created in positions such as to at least partially fill in unprinted spaces between previously created diagonal lines. Preferably the diagonal lines are all at a substantially common angle (ideally forty-five degrees) to a pen-scanning direction.