Interlaced dot-on-dot printing

Abstract

A method and apparatus for printing an image on a printing medium with phase change ink, the printing medium providing a printing area composed of a plurality of parallel pixel rows extending in a first direction, with a uniform spacing, p, between pixel rows in a second direction perpendicular to the first direction, with each row being made up of a plurality of elemental pixel areas. Printing is effected with a print head having at least one set of N nozzles for projecting drops of phase change ink onto the printing area, N being an integer and the nozzles having a uniform spacing, in a direction corresponding to the second direction when the print head faces a printing area, equal to s.multidot.p, s being an integer smaller than N and greater than unity, and relative movement is effected between the printing medium and the print head such that there are successive relative movements in the first direction while drops of phase change ink are projected onto respective pixel areas; and, in alternation with the successive movements in the first direction, there are stepwise relative movements in the second direction such that each stepwise movement in the second direction has an amplitude equal to an integral number multiple of p, which number is not equal to s, and the sum of the amplitudes of every two successive movements in the first direction is less than the product of N, s and p.