An ink jet printhead has a number of printhead chips. Each printhead chip has a wafer substrate. A plurality of nozzle arrangements is positioned on the wafer substrate. Each nozzle arrangement has nozzle chamber walls and a roof wall that define a nozzle chamber and a nozzle opening in fluid communication...http://www.google.de/patents/US6561617?utm_source=gb-gplus-sharePatent US6561617 - Nozzle guard for an inkjet printhead
