Bidirectional or unidirectional inkjet printing in accordance with a selected print mode and whether a bidirectional print alignment has been performed

摘要

The printer includes a processor (55,Fig.2) which causes bidirectional or unidirectional printing to occur using printhead cartridges (50,52,54,56,Fig. 1). The processor determines at step 113 whether a selected print mode 111 is one of a number of predetermined modes in which bidirectional printing is performed only if a bidirectional print alignment 117 has been performed. The alignment may be achieved by, for example, shifting the print data along a carriage axis for one of the opposing scan directions, in increments of the carriage axis dot resolution. If the selected mode is one of the predetermined modes, and the bidirectional alignment has been performed, then the cartridges print by bidirectional printing 119 across a print media (27,Fig. 1). If the selected mode is one of the predetermined modes, and the bidrectional alignment has not been performed, then the processor causes the cartridges to print by unidirectional printing 121 across the print media. The cartridges may be supplied from an off-axis ink delivery system (60,62,64,66,Fig.1) via a conduit (58). The printer may be used on media which is susceptible to image quality degradation due to ink drop placement misalignment, for example, due to printhead to printhead variation in drop velocity (Fig.4). The throughput of the printer is increased by bidirectional printing if bidirectional alignment has been performed.