Patent ID: 7264324

Claim:
A method for aligning a replacement ejector module with other ejector modules in a printhead array along a lateral direction, the ejector modules having nozzles that eject fluid on command, the method comprising: replacing a first replaceable ejector module or a second replaceable ejector module without replacing other ejector modules in the printhead array, arranging a first plurality of nozzles within the first module, the first plurality of nozzles including a first spacing between adjacent first nozzles along the lateral direction; arranging a second plurality of nozzles at one end of the second module, the second plurality of nozzles including a second spacing between adjacent second nozzles that differs from the first spacing along the lateral direction, the second plurality of nozzles partially overlapping the first plurality of nozzles in the lateral direction at the one end; determining an alignment pair between a first alignment nozzle of the first plurality of nozzles and a second alignment nozzle of the second plurality of nozzles, the first and second alignment nozzles minimizing an alignment spacing between each other as compared to remaining nozzles of the first and second pluralities of nozzles; and assigning the first and second alignment nozzles as first and second boundaries for print actuation, wherein determining the alignment pair further comprises: printing first lines from the first plurality of nozzles, printing second lines from the second plurality of nozzles, comparing distances between pairs of adjacent first and second lines, and selecting a pair of the adjacent first and second lines having a minimum distance therebetween.