Inkjet pens are combined in a printer so that the swaths printed by individual pens are combined into a resultant, wide swath that increases printer throughput. The print medium is carried on a drum and advanced through the printer. In a preferred embodiment, sets of two pens, each set having the same...http://www.google.de/patents/US6154232?utm_source=gb-gplus-sharePatent US6154232 - Drum-based printers using multiple pens per color
