Micro-electromechanical liquid ejection device having symmetrically actuated ink ejection components

1. A micro-electromechanical liquid ejection device that comprises

a substrate that defines a liquid inlet;

integrated drive circuitry positioned on the substrate;

a nozzle chamber assembly that defines a nozzle chamber and a liquid ejection port in fluid communication with the nozzle chamber, the nozzle chamber assembly incorporating a liquid ejection component that is movable with respect to the substrate to eject liquid from the nozzle chamber, via the port; and

at least two actuators connected to the drive circuitry and operatively arranged with respect to the liquid ejection component to move the liquid ejection component, the actuators being oriented and engaged with the liquid ejection component so that movement of the liquid ejection component is substantially rectilinear.

2. A micro-electromechanical liquid ejection device as claimed in claim 1 , in which the nozzle chamber assembly includes a static nozzle chamber structure extending from the substrate to define part of the nozzle chamber and the liquid ejection component in the form of an active nozzle chamber structure that defines the liquid ejection port and is configured to define a remaining part of the nozzle chamber, the active structure being movable with respect to the static structure towards and away from the substrate respectively to reduce and increase a volume of the nozzle chamber so that liquid in the nozzle chamber is ejected from the liquid ejection port.

3. A micro-electromechanical liquid ejection device as claimed in claim 1 , in which the active structure defines a roof with the liquid ejection port defined in the roof, and sidewalls that depend from the roof to bound the static structure.

4. A micro-electromechanical liquid ejection device as claimed in claim 3 , in which the static structure defines a liquid displacement formation that is spaced from the substrate and faces the roof, the liquid displacement structure defining a liquid displacement area that is dimensioned to facilitate ejection of liquid from the liquid ejection port, when the active structure is displaced towards the substrate.

5. A micro-electromechanical liquid ejection device as claimed in claim 3 , which includes a pair of substantially identical actuators that are connected to respective opposite sides of the roof.

6. A micro-electromechanical liquid ejection device as claimed in claim 5 , in which each actuator is a thermal bend actuator that is anchored to the substrate at one end and is movable with respect to the substrate at an opposite end, and has an actuator arm that bends when differential thermal expansion is set up in the actuator arm on receipt of the actuating electrical signal from the drive circuitry.

7. A micro-electromechanical liquid ejection device as claimed in claim 6 , which includes at least two coupling structures, one coupling structure being positioned intermediate each actuator and the active structure and each coupling structure being configured to accommodate both arcuate movement of said opposed end of each actuator and said substantially rectilinear movement of the active structure.