Patent ID: 8474930

Claim:
An ink delivery system for use in an inkjet printing apparatus comprising: a supply tank containing a supply of ink for an inkjet printhead; an inkjet printhead having a first port, a second port, an ink reservoir and an ink ejection head, with said first port, said second port and said ink ejection head being in fluid communication with one another through said ink reservoir; a pair of check valves designated as a first check valve and a second check valve, each of said first and second check valves permitting fluid flow in one direction but preventing fluid flow in the opposite direction; a bidirectional pump having a first pump port and second pump port, said bidirectional pump selectively providing positive pressure to said first pump port while providing negative pressure to said second pump port or alternatively providing negative pressure to said first pump port while providing positive pressure to said second pump port; a first fluid supply path connecting said supply tank to said inkjet printhead's first port, said first fluid supply path including said first and second check valves with said first and second check valves constructed to permit fluid flow of ink through said first fluid supply path from said supply tank to said inkjet printhead first port but preventing fluid flow in the opposite direction; a second fluid supply path connecting to said first supply path between said first and second check valves and connecting to said inkjet printhead's second port, said second fluid supply path including said bidirectional pump which directs fluid flow in either direction through said second fluid supply path; the ink delivery system operable in a print mode to communicate ink from said supply tank through said first supply path to said printhead first port and through said ink reservoir so as to eject ink from said ink ejection head; the ink delivery system operable in a recirculate mode to recirculate ink through said first supply path and said second supply path and said printhead by operating said bidirectional pump to pump ink through said second supply path from said print head second port to said first supply path which, in turn, causes ink to be communicated through said first supply path to said printhead first port; and the ink delivery system operable in a purge/fill mode to communicate ink from said supply tank to said printhead by operating said bidirectional pump to pump ink through said second supply path from first supply path to said printhead second port so as to eject ink from said ink ejection head.