Ink jet nozzle assembly including displaceable ink pusher

An ink jet printhead chip that comprises

• a substrate;
• drive circuitry positioned in the substrate;
• and
• a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising
• nozzle chamber walls and a roof wall that define a nozzle chamber and an ink ejection port in the roof wall in fluid communication with the nozzle chamber;
• an ink pusher that is operatively positioned with respect to the nozzle chamber and is displaceable through a range of between 1.5 microns and 3 microns to eject ink from the ink ejection port;
• and
• an actuator that is connected to the drive circuitry and the ink pusher to displace the ink pusher on receipt of an electrical signal from the drive circuitry, each nozzle arrangement being the product of a MEMS fabrication technique.