Modular printer having print bar chassis seated on maintenance chassis

1. A modular printer comprising:

a media support defining a media feed path; and

one or more pagewide printing units positioned along a media feed direction of the media feed path, each printing unit comprising:

a maintenance chassis fixedly positioned over the media feed path, the maintenance chassis comprising a plurality of fixedly mounted maintenance modules extending across a width of the media feed path; and

a print bar chassis seated on the maintenance chassis, the print bar chassis supporting one or more print modules extending across a width of the media feed path, each print module having a respective printhead and an associated maintenance module,

a lift mechanism for raising and lowering the print bar chassis relative to the maintenance chassis,

wherein each print bar chassis is independently liftable from a printing position in which the print bar chassis is seated on the maintenance chassis to a maintenance position in which the print bar chassis is unseated from the maintenance chassis,

and wherein a footprint of each printing unit in both the printing and maintenance positions is defined by a perimeter of the maintenance chassis.

2. The printer of claim 1 , wherein the print bar chassis comprises a plurality of print modules in a staggered overlapping arrangement across a width of the media path, each print module comprising a respective printhead.

3. The printer of claim 2 , wherein each print module is and slidably received in a sleeve fixed to the print bar chassis.

4. The printer of claim 1 , wherein the media feed path is curved media path.

5. The printer of claim 4 , wherein each maintenance chassis is fixedly positioned over a convex surface of the curved media feed path, and each print bar chassis is radially liftable with respect to the curved media path.

6. The printer of claim 1 , wherein an upper portion of the maintenance chassis defines a datum for the print bar chassis in the printing position.

7. The printer of claim 1 , wherein each print module of the print bar extends through a respective opening in the maintenance chassis in the printing position.

8. The printer of claim 1 , wherein each maintenance module comprises at least one of: a wiper and a capper.

9. The printer of claim 8 , wherein the capper is configured to move laterally with respect to the printhead and parallel with a media feed direction.

10. The printer of claim 8 , wherein the wiper is configured to move longitudinally with respect to the printhead and perpendicular to a media feed direction.

11. The printer of claim 10 , wherein wipers of neighboring printheads are configured to move in opposite longitudinal directions.

12. The printer of claim 1 , wherein each print module comprises a supply module and a replaceable printhead cartridge, the printhead cartridge comprising the printhead.

13. The printer of claim 12 , wherein the supply module houses at least one PCB having a printer controller chip for controlling a respective printhead.

14. The printer of claim 12 , wherein the supply module comprises an ink inlet module and an ink outlet module for supplying ink to and receiving ink from the printhead cartridge.

15. A method of maintaining a plurality of printheads:

providing a maintenance chassis positioned over a media feed path in a fixed relationship relative to the media support, the maintenance chassis comprising a plurality of fixedly mounted maintenance modules extending across a width of the media feed path;

providing a print bar chassis seated on the maintenance chassis, the print bar chassis supporting a plurality of print modules in a staggered overlapping arrangement across a width of the media feed path, each print module comprising one of the printheads and an associated maintenance module;

lifting the print bar chassis relative to the maintenance chassis from a printing position to a maintenance position; and

moving a capper or a wiper of each maintenance module into engagement with a respective printhead,

wherein a footprint of the printing unit in both the printing and maintenance positions is defined by a perimeter of the maintenance chassis.

16. The method of claim 15 , wherein the media feed path is arcuate and each maintenance chassis is positioned over a convex surface of the arcuate media feed path, wherein the method radially lifts the print bar chassis with respect to the arcuate media path.