Stable substrate structure for a wide swath nozzle array in a high resolution inkjet printer

A method of using a print cartridge in an inkjet printer, said print cartridge including a printhead having an array of ink nozzles aligned respectively over a plurality of firing chambers, said method comprising the steps of:

• moving said printhead with respect to a medium in said inkjet printer, said printhead including a substrate;
• providing electrical signals to said substrate to eject droplets of ink from said ink nozzles, said substrate including end portions with one or more columns of firing chambers located on said substrate between said end portions, with said firing chambers extending in a longitudinal direction along at least one outer edge of said substrate and spaced less than 1/500th of an inch apart in said longitudinal direction so as to eject said droplets of ink on said medium at a dots per inch resolution of less than 1/500th of an inch in said longitudinal direction as said printhead moves with respect to said medium in a direction perpendicular to said longitudinal direction;
• supplying ink through ink channel means connecting an ink reservoir with said firing chambers, said ink channel means for passing ink from an underside of said substrate around an outer edge of said substrate to said firing chambers;
• and
• supplying ink to said ink reservoir.