A method and apparatus for positioning a fluid ejection device such as an inkjet pen, or a plurality of aligned fluid ejection devices, on a supporting frame known as a printbar for page wide array printing involves provision of datum surfaces on each ejection device extending in three orthogonally related...http://www.google.de/patents/US6467874?utm_source=gb-gplus-sharePatent US6467874 - Pen positioning in page wide array printers
