Pagewidth printhead assembly
View Patent ↗A page width printhead assembly ( 1 ) for a digital inkjet printer has a support member that can be secured in the printer, and a printhead ( 2 ) that can be mounted to the support member. The support member has a core with at least one ink reservoir ( 6, 7, 8 and 9 ) enclosed within a laminated shell ( 4 ). The materials and structure of the shell ( 4 ) and the core ( 5 ) are selected and configured so that the co-efficient of thermal expansion of the support member as a whole is substantially equal to that of the printhead ( 2 ).
1. A pagewidth printhead assembly for a page width printer, the assembly comprising:
a support member having an outer laminated shell portion and a core portion at least partially enclosed and restrained by the shell portion; and
a modular, pagewidth printhead mounted to the core portion, wherein the shell portion and the printhead have substantially the same effective coefficient of thermal expansion.
2. A printhead assembly according to claim 1 , wherein:
the pagewidth printhead is stationary and generally as long as the page width.
3. A printhead assembly according to claim 2 , wherein:
the shell portion is a laminated structure having an odd number of longitudinally extending continuous layers of at least two different metals wherein at least some of the layers are in a symmetrical arrangement.
4. A printhead assembly according to claim 1 , wherein:
the core portion has formed in it one or more ink reservoirs which collectively lead to one or more printhead micro mouldings which are carried by the core.
5. A printhead assembly according to claim 1 , wherein:
the laminated shell portion is formed from at least three metals laminated together, the laminate having inner and outer layers which have the same coefficient of thermal expansion.
6. A printhead assembly according to claim 1 , wherein:
the printhead is fabricated from silicon and constructed using micro electromechanical techniques.
7. A printhead assembly according to claim 1 , wherein:
the core portion is an extrusion in which is formed separate ink reservoirs.
8. A printhead assembly according to claim 1 , wherein:
the modular printhead comprises MEMS modules which are positioned end to end along the core.
9. A printhead assembly according to claim 8 , wherein:
each module further comprises ink nozzles, chambers and actuators.
10. A printhead assembly according to claim 1 , wherein:
the laminated shell portion comprises two or more different materials, each having a different coefficient of thermal expansion.
11. A printhead assembly according to claim 10 , wherein:
at least two materials have coefficients of expansion which are different than the coefficient of expansion of silicon.
12. A printhead assembly according to claim 11 , wherein:
the laminated shell portion comprises outer layers of invar.
13. A printhead assembly according to claim 1 , wherein:
the assembly has a composite coefficient of expansion generally equal to the coefficient of expansion silicon.