Printhead assembly for a pagewidth printer
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, at least two laminae of the laminated shell portion having coefficients of thermal expansion different from each other and from that of silicon; and
a modular pagewidth printhead mounted to the core portion, the printhead being formed from one or more silicon structures,
wherein the at least two laminae of the laminated shell portion have thicknesses different form each other such that the effective coefficient of thermal expansion of the laminated shell portion is substantially equal to that of silicon.
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.