CONSTRAINT SOLVING FOR INKJET PRINT MASK DESIGN

We present results in a constraint solving approach for automatic generation of inkjet print masks. Print masks are used to control the firing of the nozzles, that is, to determine which nozzles on an inkjet printer cartridge are to spit an ink droplet at each particular instant in a multiple-pass print mode. Many design rules for print masks can be modeled in terms of constraints and cost functions. For example, if adjacent nozzles are fired simultaneously, printing artifacts often result. Therefore, spatial adjacency constraints with respect to horizontal, vertical and diagonal neighbors are modeled with various cost functions. Minimizing the associated, total costs then generates the print masks. Initial solutions are found by a greedy algorithm with some randomization; then neighborhood search techniques are applied to find local near-optima. Our approach can generate masks for Inkjet printers in multiple-pass print modes for multiple-level, multiple-drop technologies. It has been used to help design the print masks for Hewlett Packard's wide format printers (DeskJet 2500C and 2500CM). This approach can shorten the turnaround time for print mask design in a systematic and methodical way.