Modular inkjet printhead with mating formations

1. A pagewidth printhead for an inkjet printer, the printhead comprising:

an elongate support;

a plurality of printhead modules supported by the support, each printhead module comprising rows of unit cells, each unit cell comprising a nozzle through which ink is ejected and an actuator for ejecting ink from the nozzle; and

an engagement mechanism having complementary formations defined on opposite edges of each printhead module to engage the printhead modules together in series along the support, wherein

the engagement mechanism includes a biasing means configured to press the serially arranged printhead modules together,

said biasing means includes at least one compression spring; and

a gap is defined between the unit cells of adjacent printhead modules, the gap extending obliquely with respect to the support.

2. A printhead as claimed in claim 1 , wherein said at least one compression spring comprises a pair of compression springs each pressing against respective endmost printhead modules.

3. A printhead as claimed in claim 1 , wherein each printhead module defines serrated formations so that the printhead modules can be interlocked together in series.

4. A printhead as claimed in claim 3 , wherein each serrated formation comprises a pair of planar walls terminating in an apex and one of the walls aligned with the support.

5. A printhead as claimed in claim 1 , wherein aligned rows of adjacent printhead modules are configured to eject different types of ink.

6. A printhead as claimed in claim 1 , wherein the unit cells in each row are equidistantly spaced from each other.