PRINTHEAD HAVING DUAL ARM EJECTION ACTUATORS
A printhead is provided which has a plurality of fluid chambers and nozzles for ejection of fluid from the chambers defined on a substrate having electrical circuitry. Each chamber has an actuator cantilevered on the substrate with a first arm connected to the electrical circuitry and a second arm connected at each end to the first arm. Electrical current from the electrical circuitry causing heating and expansion of the first arm relative to the second arm thereby deflecting the actuator relative to the substrate. Each actuator has an ejection member connected to the free end and positioned within the chamber so that the deflection of the actuator causes displacement of the ejection member resulting in ejection of fluid from the chamber through the nozzle.
1 . A printhead comprising a plurality of fluid chambers and nozzles for ejection of fluid from the chambers defined on a substrate having electrical circuitry, each chamber having an actuator cantilevered on the substrate with a first arm connected to the electrical circuitry and a second arm connected at each end to the first arm, electrical current from the electrical circuitry causing heating and expansion of the first arm relative to the second arm thereby deflecting the actuator relative to the substrate, each actuator having an ejection member connected to the free end and positioned within the chamber so that the deflection of the actuator causes displacement of the ejection member resulting in ejection of fluid from the chamber through the nozzle.
2 . A printhead as claimed in claim 1 , in which each chamber has an opening through which the actuator arms extend, the chambers and actuators being configured so that surface tension effects of the fluid within the chamber form a fluidic seal between the chamber and actuator arms.
3 . A printhead as claimed in claim 1 , in which the substrate has a recess about each chamber to inhibit wicking of fluid across the substrate.
4 . A printhead as claimed in claim 1 , in which the substrate has a plurality of fluid inlets for supplying fluid to the chambers.
5 . A printhead as claimed in claim 1 , in which each ejection member has a peripheral projection positioned to project towards the nozzle.
6 . A printhead as claimed in claim 1 , in which each actuator has a heat sink positioned on the first arm intermediate the ends.
7 . A printhead as claimed in claim 1 , in which each actuator has at least one strut on each arm intermediate the ends.