Multi-ink Printhead Dot Pattern Control for Printing Speed

The patent divides the printing process into multiple passes, with each pass dedicated to specific ink types. The controller segments the dot formation tasks by ink type and pass number, allowing different nozzle groups to operate independently in each pass without being constrained by the total nozzle count mismatch. This segmentation enables parallel processing of different ink types across multiple passes, resolving the speed limitation caused by having to wait for all nozzle types to complete their respective dot formations.

The controller performs preliminary planning of the printing process by determining the optimal assignment of dot formation tasks to each pass and nozzle group before actual printing begins. It pre-calculates which nozzles should form dots in each pass based on the image data and nozzle characteristics, ensuring that boundary areas between different ink ranges are properly handled in advance. This preliminary action allows the system to maintain smooth transitions between ink ranges by coordinating the discharge timing and positions across multiple passes.

The controller applies partial action by selectively determining which overlap areas require additional discharge operations and which do not. Instead of uniformly increasing discharge operations across all overlap areas, the controller intelligently identifies regions where boundary smoothness is critical and applies additional discharge operations only to those specific areas. This selective approach maintains print quality at boundaries while minimizing the overall number of discharge operations, thereby preserving printing speed in non-critical areas.