Printhead assembly with relative thermal expansion inhibition

1. A printhead assembly which comprises

an elongate support member;

an elongate ink delivery member mounted in the support member and defining a number of ink delivery conduits extending along the support member and a series of patterned holes in fluid communication with the ink delivery conduits; and

a series of printhead modules engaged with the support member and positioned end-to-end along the support member, each printhead module including an ink distribution structure in fluid communication with the holes of the ink delivery member and a printhead integrated circuit mounted on the ink distribution structure to receive ink from the ink distribution structure, a substrate of the printhead integrated circuit and the support member having substantially the same coefficient of thermal expansion.

2. A printhead assembly as claimed in claim 1 , in which the support member is an elongate channel member having a floor and a pair of opposed side walls, the elongate channel member being of a metal having thermal expansion properties that are similar to thermal expansion properties of silicon.

3. A printhead assembly as claimed in claim 2 , in which the elongate channel is of a nickel iron alloy.

4. A printhead assembly as claimed in claim 3 , in which the elongate channel is a 36% nickel iron alloy.

5. A printhead assembly as claimed in claim 2 in which the channel member and the printhead modules have complementary clipping arrangements to permit the printhead modules to be clipped into the channel member.

6. A printhead assembly as claimed in claim 5 , in which each ink distribution structure defines a mounting formation to permit the printhead integrated circuit to be mounted on the ink distribution structure, a plurality of ink inlets that are in fluid communication with the holes of the ink delivery member, a plurality of exit holes and tortuous ink flow paths from each ink inlet to a number of respective exit holes, each printhead integrated circuit incorporating a plurality of nozzle arrangements that extend along a length of the printhead integrated circuit that is positioned so that the ink can be fed from the exit holes to the printhead integrated circuit.

7. A printhead assembly as claimed in claim 6 , in which the ink delivery member is in the form of an extrusion of an elastomeric material, the delivery conduits extending longitudinally in the extrusion and the holes defined in a surface of the extrusion in fluid communication with respective ink delivery conduits.