Efficient inkjet nozzle assembly

1. An inkjet nozzle assembly comprising:

a nozzle chamber for containing ink, said chamber having a nozzle opening and an ink inlet;

a pair of electrical contacts positioned at one end of said assembly and connected to drive circuitry; and

a thermal bend actuator for ejecting ink through the nozzle opening, said actuator comprising:

an active beam connected to said electrical contacts and extending longitudinally away from said contacts, said active beam defining a bent current flow path between said contacts; and

a passive beam fused to said active beam, such that when a current is passed through the active beam, the active beam heats and expands relative to the passive beam resulting in bending of the actuator,

wherein said actuator has a working face for generating a positive pressure pulse in said ink during said bending of said actuator, said working face having an area of less than 800 square microns.

2. The inkjet nozzle assembly of claim 1 , wherein said working face has an area of less than 600 microns.

3. The inkjet nozzle assembly of claim 1 , wherein said working face is defined by a face of said passive beam.

4. The inkjet nozzle assembly of claim 1 , which is configured to provide a peak actuator velocity of at least 2.5 m/s.

5. The inkjet nozzle assembly of claim 1 , wherein said drive circuitry is configured to deliver actuation pulses to said active beam, each actuation pulse delivering less than 200 nJ of energy to said active beam.

6. The inkjet nozzle assembly of claim 1 , wherein said drive circuitry is configured to deliver actuation pulses to said active beam, each actuation pulse having a pulse width of less than 0.2 microseconds.

7. The inkjet nozzle assembly of claim 1 , wherein said active and passive beams each have a length of less than 50 microns.

8. The inkjet nozzle assembly of claim 1 , wherein said active and passive beams each have a width of less than 15 microns.

9. The inkjet nozzle assembly of claim 1 , wherein said active and passive beams have a combined thickness of at least 1.5 microns.

10. The inkjet nozzle assembly of claim 9 , wherein each of said first and second arms comprises a respective resistive heating element having a width of less than 5 microns.

11. The inkjet nozzle assembly of claim 9 , wherein said connecting member interconnects distal ends of said first and second arms, said distal ends being distal relative to said electrical contacts.

12. The inkjet nozzle assembly of claim 1 , wherein said active beam comprises a first arm extending longitudinally from a first contact, a second arm extending longitudinally from a second contact and a connecting member connecting said first and second arms.

13. The inkjet nozzle assembly of claim 1 , wherein said active beam is comprised of a material selected from the group comprising: titanium nitride, titanium aluminium nitride and a vanadium-aluminium alloy.

14. The inkjet nozzle assembly of claim 1 , wherein said passive beam is comprised of a material selected from the group comprising: silicon dioxide, silicon nitride and silicon oxynitride.

15. The inkjet nozzle assembly of claim 1 , wherein the nozzle chamber comprises a floor and a roof having a moving portion, whereby actuation of said actuator moves said moving portion towards said floor.

16. The inkjet nozzle assembly of claim 15 , wherein said moving portion comprises said actuator.

17. The inkjet nozzle assembly of claim 16 , wherein the nozzle opening is defined in the moving portion, such that the nozzle opening is moveable relative to the floor.

18. The inkjet nozzle assembly of claim 1 , wherein said inkjet nozzle assembly has a footprint area of less than 1500 square microns.

19. An inkjet printhead comprising a plurality of nozzle assemblies according to claim 1 .