MEMS device with movement amplifying actuator
View Patent ↗A micro-electromechanical liquid ejection device includes a substrate that defines a liquid inlet channel. Drive circuitry is positioned on the substrate. A nozzle chamber structure is positioned on the substrate and defines a nozzle chamber in fluid communication with the liquid inlet channel and a liquid ejection port in fluid communication with the nozzle chamber. A liquid ejecting mechanism is operatively arranged with respect to the nozzle chamber such that movement of the liquid ejecting mechanism results in the ejection of liquid from the liquid ejection port. An actuator is fast with the substrate and is connected to the drive circuitry to be displaced relative to the substrate on receipt of an electrical signal from the drive circuitry. The actuator is connected to the liquid ejecting mechanism to cause said movement of the liquid ejecting mechanism. The liquid ejecting mechanism has a liquid ejecting member that acts on liquid in the nozzle chamber. The actuator and the liquid ejecting mechanism are configured so that an extent of displacement of the actuator is amplified in movement of the liquid ejecting member.
1. A micro-electromechanical (MEMS) device for ejecting a drop of liquid, the MEMS device comprising:
a supporting substrate;
a chamber formed on the substrate for holding a quantity of the liquid;
an actuator attached to the substrate for movement relative to the substrate;
a liquid ejecting mechanism attached to the actuator for movement within the chamber;
drive circuitry on the substrate for generating drive signals to drive the actuator; and,
an ejection port in fluid communication with the chamber such that movement of the liquid ejecting mechanism in response to the actuator receiving a drive signal causes a drop of the liquid ejecting through the ejection port; wherein,
actuation of the actuator causes greater movement of the liquid ejecting mechanism relative to the substrate than the actuators movement relative to the substrate.
2. A MEMS device according to claim 1 wherein the actuator includes a force transmitting portion that is substantially linearly displaceable upon receipt of the signal from the drive circuitry and the liquid ejecting mechanism includes a micro-mechanical translating mechanism interposed between the force transmitting portion and the liquid ejecting member such that displacement of the force transmitting portion results in said movement of the liquid ejecting member.
3. A MEMS device according to claim 2 wherein the actuator includes an anchor arrangement that is fast with the substrate and extends from the substrate, the force transmitting portion being a thermal expansion member extending from the substrate to be spaced from the substrate and defining a heating circuit electrically connected to the drive circuitry layer to receive an electrical signal from the drive circuitry layer so that the expansion member expands and subsequently contracts.
4. A MEMS device according to claim 3 wherein the force transmitting portion is a lever mechanism with the liquid ejecting mechanism providing a resistance and the expansion member providing an effort.
5. A MEMS devices according to claim 4 wherein the lever mechanism includes a pivot member pivotally mounted in one of the walls of the chamber to define a fulcrum along a pivot line and interposed between the expansion member and the liquid ejection mechanism at expansion and subsequent contraction of the expansion member results in pivotal movement of the liquid ejection mechanism towards and away from the ejection port.
6. A MEMS device according to claim 1 wherein the chamber includes nozzle chamber walls and the liquid ejection port is defined in a roof that spans the walls.