US Patent 7997690 Inkjet printer

An inkjet printer including: a printhead having a plurality of nozzles assemblies, each nozzle assembly having: a nozzle chamber for containing ink, the chamber having a nozzle opening and an ink inlet; and a bend actuator for ejecting ink droplets from the nozzle opening by generating a positive pressure pulse in the ink during bending of the actuator. An ink supply system supplies ink to the printhead so that a hydrostatic pressure of ink can be varied. Increasing the hydrostatic ink pressure increases a volume of the ejected ink droplets, and decreasing the hydrostatic ink pressure decreases a volume of the ejected ink droplets.