Micro-electromechanical fluid ejection device with an array of nozzle assemblies incorporating fluidic seals
View Patent ↗A micro-electromechanical fluid ejection device includes a substrate. Drive circuitry is positioned on the substrate. A plurality of fluid supply channels is defined in the substrate. An array of nozzle assemblies is positioned on the substrate. Each defines nozzle chambers in fluid communication with the fluid supply channels. Each has a fixed nozzle chamber structure extending from the substrate and a movable nozzle chamber structure that is movable towards and away from the substrate to reduce and subsequently expand a nozzle chamber volume. The movable nozzle chamber structure defines an ejection port from which the fluid is ejected as a result of the change in volume of the nozzle chamber. A plurality of actuators is connected to the drive circuitry. Each actuator is operable on a respective movable nozzle chamber structure. The nozzle chamber structures of each nozzle assembly are configured and positioned with respect to each other so that, when the nozzle chambers are filled with fluid, menisci are set up between the nozzle chamber structures of respective pairs to define fluidic seals and thereby inhibit the egress of ink from between the nozzle chamber structures of each pair.
1. A micro-electromechanical fluid ejection device that comprises
a substrate;
drive circuitry positioned on the substrate;
a plurality of fluid supply channels defined in the substrate;
an array of nozzle assemblies positioned on the substrate and defining nozzle chambers in fluid communication with the fluid supply channels, each nozzle assembly comprising a fixed nozzle chamber structure extending from the substrate and a movable nozzle chamber structure that is movable towards and away from the substrate to reduce and subsequently expand a nozzle chamber volume, the movable nozzle chamber structure defining an ejection port from which the fluid is ejected as a result of the change in volume of the nozzle chamber; and
a plurality of actuators connected to the drive circuitry and operable on respective movable nozzle chamber structures, wherein
the nozzle chamber structures of each nozzle assembly are configured and positioned with respect to each other so that, when the nozzle chambers are filled with fluid, menisci are set up between the nozzle chamber structures of respective pairs to define fluidic seals and thereby inhibit the egress of ink from between the nozzle chamber structures of each pair.
2. A micro-electromechanical fluid ejection device as claimed in claim 1 , in which each fixed nozzle chamber structure includes a wall portion that bounds the associated fluid supply channel and each movable nozzle chamber structure includes a crown portion that defines the ejection port and a skirt portion that depends from the crown portion, the wall portion and the skirt portion being configured and positioned with respect to each other to define said fluidic seal.
3. A micro-electromechanical fluid ejection device as claimed in claim 2 , in which each wall portion has a peripheral, inwardly directed lip and each skirt portion has a peripheral edge, the lip and the edge being configured to pin a meniscus between the wall portion and the skirt portion.
4. A micro-electromechanical fluid ejection device as claimed in claim 2 , in which each actuator is elongate, with one end fast with the substrate and connected to the drive circuitry and an opposite end fast with a respective crown portion.
5. A micro-electromechanical fluid ejection device as claimed in claim 4 , in which each actuator is configured to experience differential thermal expansion and contraction on receipt of an electrical pulse from the drive circuitry.
6. A micro-electromechanical device as claimed in claim 1 , in which a nozzle guard is mounted on the substrate and spaced from the nozzle assemblies, the nozzle guard defining a plurality of passages substantially aligned with respective ejection ports so that fluid ejected from the ports can pass through the passages.
7. A micro-electromechanical device as claimed in claim 6 , in which the nozzle guard comprises a substantially planar cover member that defines the passages and a plurality of struts that support the cover member in spaced relationship relative to the array of nozzle assemblies.