Printhead having inkjet actuators with contractible chambers
View Patent ↗An ink printhead is provided having a plurality of nozzle assemblies. Each nozzle assembly has a nozzle and an actuator for ejecting ink through the nozzle. Each actuator has a resiliently contractible chamber.
1. An ink printhead comprising a plurality of nozzle assemblies, each nozzle assembly comprising:
a nozzle and an actuator for ejecting ink through said nozzles, wherein,
the actuator comprises a resiliently contractible chamber having four slidable walls each slidable by thermal actuation, each slidable wall being a side wall of the chamber.
2. An inkjet printhead according to claim 1 , wherein each nozzle assembly further comprises an ink inlet for communicating ink between the chamber and an ink reservoir.
3. An inkjet printhead according to claim 2 wherein each ink inlet is defined in an inlet wall of the respective chamber and the nozzle is defined in a nozzle wall of the respective chamber which is spaced from the inlet wall and connected thereto by the at least one slidable wall.
4. An inkjet printhead according to claim 1 wherein the four side walls are arcuate vanes arranged around a central axis, and the actuator further comprises four expanding, flexible arms each connected to a respective vane, such that simultaneous actuation of the arms pushes the arcuate vanes to slidingly engage each other to contract the chamber.
5. An inkjet printhead according to claim 4 wherein said flexible expanding arms comprise a conductive heater material encased within an expansion material having a high coefficient of thermal expansion.
6. An inkjet printhead according to claim 5 wherein said conductive heater material is constructed so as to form a concertina upon expansion of said expansion material.
7. An inkjet printhead according to claim 5 wherein said heater material is of a serpentine form and forms a concertina upon heating so as to allow substantially unhindered expansion of said expansion material during heating.
8. An inkjet printhead according to claim 5 wherein said vanes are arranged annularly around said nozzle.
9. An inkjet printhead according to claim 5 wherein said vanes operate as an iris around said nozzle.
10. An inkjet printhead according to claim 5 wherein said expansion material substantially comprises polytetrafluoroethylene.
11. An inkjet printhead according to claim 5 wherein said conductive heater material substantially comprises copper.