Ink jet printhead chip with planar actuators

摘要

A printhead chip for an inkjet printhead includes a wafer substrate that incorporates drive circuitry and defines a plurality of ink inlet channels. A plurality of nozzle arrangements is positioned on the wafer substrate. Each nozzle arrangement includes side walls and a roof wall positioned on the substrate to define a nozzle chamber such that one of the ink inlet channels opens into the nozzle chamber. The roof wall defines an ink ejection port. A substantially planar, elongate actuator is positioned in the nozzle chamber to overlie the respective ink inlet channel. The actuator incorporates a heater layer that comprises an electrical circuit that is connected to the drive circuitry layer at one end of the actuator and at least one expansion layer that is fast with the heater layer. The heater layer is positioned so that the expansion layer experiences differential thermal expansion and contraction when the heater layer receives an electrical signal from the drive circuitry layer and the actuator is displaced towards and away from the ink ejection port to eject a drop of ink from the nozzle chamber.