Printhead with nozzle guard alignment
View Patent ↗A printhead includes a substrate that defines a plurality of ink inlet conduits. A plurality of nozzle assemblies is positioned on the substrate. Each nozzle assembly defines a nozzle chamber in fluid communication with a respective ink inlet conduit and a nozzle opening from which ink is ejected. A plurality of alignment formations is positioned on the substrate to extend from the substrate. A guard member is positioned on the substrate and spaced from the nozzle assemblies. The guard member defines a plurality of apertures that correspond with respective nozzle openings. A plurality of struts is positioned on the guard member and is engageable with respective alignment formations. The struts and the alignment formations are positioned so that, when each strut engages an alignment formation, the apertures are aligned with respective nozzle openings.
1. A printhead that comprises
a substrate that defines a plurality of ink inlet conduits;
a plurality of nozzle assemblies that are positioned on the substrate, each nozzle assembly defining a nozzle chamber in fluid communication with a respective ink inlet conduit and a nozzle opening from which ink is ejected;
a plurality of alignment formations that are positioned on the substrate to extend from the substrate;
a guard member that is positioned on the substrate and spaced from the nozzle assemblies, the guard member defining a plurality of apertures that correspond with respective nozzle openings; and
a plurality of struts that are positioned on the guard member and are engageable with respective alignment formations, the struts and the alignment formations being positioned so that, when each strut engages an alignment formation, the apertures are aligned with respective nozzle openings.
2. A printhead as claimed in claim 1 , in which a plurality of containment walls are disposed about respective nozzle assemblies and interposed between the substrate and the guard member to define a plurality of containment chambers, at least one nozzle assembly being positioned in a respective containment chamber.
3. A printhead as claimed in claim 2 , in which one nozzle assembly is positioned in each containment chamber.
4. A printhead as claimed in claim 1 , in which the substrate incorporates drive circuitry and each nozzle assembly includes a micro-electromechanical ink ejection mechanism that is connected to the drive circuitry to eject ink from the nozzle chamber on receipt of a signal from the drive circuitry.
5. A printhead as claimed in claim 4 , in which each micro-electromechanical ink ejection mechanism includes a thermal bend actuator that is connected to the drive circuitry to be deflected as a result of differential thermal expansion and contraction on receipt of an electrical signal from the drive circuitry, and an ink displacement member that is connected to the thermal bend actuator, the ink displacement member being operatively arranged with respect to the nozzle chamber so that deflection of the thermal bend actuator results in the ejection of ink from the nozzle chamber.
6. A printhead as claimed in claim 5 , in which each ink displacement member defines part of the nozzle chamber such that movement of the ink displacement member under action of the thermal bend actuator results in a change in volume of the nozzle chamber and subsequent ejection of ink from the nozzle chamber.
7. A printhead as claimed in claim 1 , in which the substrate and the guard member are of materials that have the same coefficient of thermal expansion.
8. A printhead as claimed in claim 1 , in which a seal is interposed between each strut and its associated alignment formation.