Nozzle arrangement with nozzle having dynamic and static ink ejection structures

1. A nozzle arrangement for an inkjet printhead, the nozzle arrangement comprising:

a substrate defining an ink inlet channel; and

a nozzle comprising a static structure extending from the substrate and surrounding the ink inlet channel and a dynamic structure surrounding the static structure and movably mounted with respect to the static structure to define a variable-volume nozzle chamber in fluid communication with the ink inlet channel; the dynamic structure further defining an ink ejection port through which ink can be ejected when the dynamic structure is moved relative to the static structure; the static structure defining an internal surface configured to facilitate ink ejection when the dynamic structure moves relative to the static structure decreasing a volume of the nozzle chamber.

2. A nozzle arrangement as claimed in claim 1 , wherein the internal surface has a substantially flat profile facing a direction of ink ejection.

3. A nozzle arrangement as claimed in claim 2 , wherein the dynamic structure includes a roof structure that defines the ink ejection port and a wall that depends from the roof structure.

4. A nozzle arrangement as claimed in claim 3 , wherein the wall is orthogonal to said internal surface.

5. A nozzle arrangement as claimed in claim 1 , wherein said internal surface is defined by a free end portion of a wall extending from the substrate.

6. A nozzle arrangement as claimed in claim 5 , wherein said free end portion comprises a sealing structure that extends towards the wall of the dynamic structure and a ledge extending into the nozzle chamber.

7. A nozzle arrangement as claimed in claim 6 , in which the sealing structure has a reentrant profile.