Stable printhead assembly
View Patent ↗Disclosed is a stable printhead assembly ( 1 ) for carrying a printhead ( 2 ) such as modular MEMS printhead. The assembly has an elongated core ( 5 ) and for example, a MEMS printhead bonded to the core. The core is contained within an outer laminated shell ( 4 ). The shell and core together have an effective coefficient of thermal expansion substantially equal to that of the printhead.
1. A printhead assembly for carrying a printhead, comprising:
an elongated core;
a MEMS printhead bonded to the core;
the core being contained within an outer laminated shell, the shell and core together having an effective coefficient of thermal expansion substantially equal to that of the printhead.
2. A printhead assembly according to claim 1 , wherein:
the outer shell is formed from different materials laminated together, the laminate having inner and outer layers which are of the same metal.
3. A printhead assembly according to claim 2 , wherein:
the laminated shell comprises inner and outer layers of invar.
4. A printhead assembly according to claim 1 , wherein:
the printhead is fabricated from silicon.
5. A printhead assembly according to claim 1 , wherein:
the outer shell has an odd number of longitudinally extending layers, being at least three in number, layers being arranged symmetrically about a central layer.
6. A printhead assembly according to claim 5 , wherein:
the laminated shell comprises two or more different materials, each having a different coefficient of thermal expansion.
7. A printhead assembly according to claim 1 , wherein:
a coefficient of thermal expansion of the core and a coefficient of thermal expansion of the shell are different.
8. A printhead assembly according to claim 1 , wherein:
the extrusion comprises adjacent reservoirs which collectively lead to an area adapted to receive a printhead which is carried by the core.
9. A printhead assembly according to claim 1 , wherein:
the core is an extruded and elongated body having a plurality of interior reservoirs, the reservoirs each having an ink exit opening, the openings converging into an area adapted to receive the printhead.
10. A printhead assembly according to claim 1 , wherein:
the body is a plastic extrusion.
11. A printhead assembly according to claim 10 , wherein:
the body is internally subdivided by extruded membranes to define the reservoirs.
12. A printhead assembly according to claim 11 , wherein:
the reservoirs are four in number.
13. A printhead assembly according to claim 1 , wherein:
the core is adapted to be encased by the shell, the body and shell.
14. A printhead assembly according to claim 13 , wherein:
the body includes a portion which protrudes beyond the shell, this portion receiving the printhead.
15. A printhead assembly according to claim 1 , wherein:
the core has a coefficient of expansion which is less than the coefficient of expansion of silicon, and the shell has a coefficient of expansion which is greater than the coefficient of expansion of silicon.
16. A printhead assembly according to claim 1 , wherein:
the shell comprises at least two materials bonded to one another and having coefficients of expansion which are different than the coefficient of expansion of silicon, one material having a coefficient of expansion which is greater than the coefficient of expansion of silicon and another material having a coefficient of expansion which is less than the coefficient of expansion of silicon.
17. A printhead assembly according to claim 1 , wherein:
the laminated shell comprises hot rolled layers of metal.
18. A printhead assembly according to claim 1 , further comprising:
a modular printhead bonded to the core, the printhead comprising a plurality of modules disposed along the core.
19. A printhead assembly according to claim 18 , wherein:
each module is fabricated from silicon.
20. A printhead assembly according to claim 19 , wherein:
each module further comprises a MEMS structure.