Abstract: A printer apparatus and method of actuating a fluid pump in a printer to deliver fluid to an ink jet printhead without removing the printhead from a printhead carriage particularly useful for priming inkjet printheads using an air displacement pump to deliver air under positive pressure to the printheads. The pump is located proximate a service station on the printer and is automatically actuated by movement of the carriage to service station. The pump may be arcuately positionable to align the pump with a selected one of air passageways provided in a printhead holddown cover on the printhead carriage. Algorithms are provided for locating the precise position of the pump outlet along the carriage scan axis relative to its intended design location and for arcuately positioning the pump relative to the carriage to engage the pump outlet with a selected one of conduits in the carriage connected to each printhead.

Abstract: A printhead carriage for an ink jet printer having a plurality of printhead stalls therein and a printhead holddown cover having spring biased printhead holddown plungers on the underside of the cover and equal volume fluid passageways in the cover for conducting fluid from fluid inlets on said cover exposed to atmosphere to printheads in the stalls. An arcuately moveable air pump is engageable with one of a number of arcuately positioned inlets to the passageways in the carriage cover to enable a single pump to selectively apply positive pressure to prime each of the printheads in a desired sequence.