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1. An inkjet printer with a printhead assembly and at least one replaceable ink cartridge, the inkjet printer comprising:an ink inlet valve on the printhead assembly for sealed connection to an outlet on the ink cartridge, the inlet valve having an inlet opening and a movable valve member biased into sealing engagement with the inlet opening, the outlet having a complementary member for depressing the movable valve member out of engagement with the inlet opening to open the valve; wherein,the inlet opening has an external formation about its periphery for sealing against the outlet before the complementary member depresses the movable valve member.
2. An inkjet printer according to claim 1 wherein the printhead assembly is a printhead cartridge for installation in the inkjet printer.
3. An inkjet printer according to claim 1 wherein the inlet opening is a hole defined by a ring member, the external formation is an outer surface of the ring member, and an inner surface opposite the outer surface provides a valve seat for the movable valve member.
4. An inkjet printer according to claim 3 wherein the moveable valve member has a conical head for sealing against the valve seat supported on a base of compressible resilient material such that the complementary member compresses the base to open the inlet valve.
5. An inkjet printer according to claim 4 wherein the conical head has an apex that does not extend beyond the outer surface of the ring member so that the complementary member is within the inlet opening when the complementary member engages the conical head.
6. An inkjet printer according to claim 5 wherein the complementary member has a stem with a flange portion on its end, the flange portion having a recess corresponding to the apex end of the conical head, the flange portion having a diameter sized for a loose sliding fit within the inlet opening to displace substantially all the air from between the complementary member and the conical head before the inlet valve is opened.
7. An inkjet printer according to claim 6 wherein the ink cartridge outlet has an annular collar of resilient material that is biased to seal against the side of the flange portion opposite the recess, such that during use the external formation on the inlet valve seals against the annular collar of resilient material before the flange portion depressed the conical head to open the inlet valve.
8. An inkjet printer according to claim 7 wherein the external formation on the inlet valve seals against the annular collar immediately adjacent to the sides of the flange portion such that minimal air is trapped between the sides of the flange portion and the external formation.
9. An inkjet printer according to claim 8 wherein the ring member and the external formation are located within a frustoconical tube that tapers toward the outlet of the ink cartridge to guide the ink cartridge into correct position during installation.
10. An inkjet printer according to claim 7 further comprising a filter adjacent the inlet valve for trapping air bubbles and contaminants.
11. An inkjet printer according to claim 10 wherein the filter has a surface area larger than the area of the inlet opening such that its pore size is kept small while adversely constricting the ink flow.
12. An inkjet printer according to claim 11 further comprising a pressure regulator to cut fluid communication between the inlet valve and the nozzles if the pressure difference across the pressure regulator is below a certain threshold.
13. An inkjet printer according to claim 12 wherein the pressure regulator has a diaphragm biased to seal against a regulator valve seat such that upstream pressure acts on one side of the diaphragm and down stream pressure acts the opposite side.
14. An inkjet printer according to claim 13 wherein the diaphragm and the filter are circular, adjacent and have similar diameters.
15. An inkjet printer according to claim 2 wherein the printhead cartridge has a casing that supports a pagewidth printhead and the printer body has a cradle for holding the printhead cartridge in an operative position such that the pagewidth printhead is adjacent a paper path defined by the printer body; wherein,during insertion, the cradle and the casing interact to form an over centre mechanism whereby, the printhead cartridge rotates against a bias prior until reaching a balance point, after which the printhead cartridge is biased to rotate into the operative position.
16. An inkjet printer according to claim 2 wherein the printhead cartridge has a casing that supports a pagewidth printhead and a plurality of contacts for receiving print data from corresponding contacts on the printer body;the printer body having a cradle for holding the printhead cartridge in an operative position such that the pagewidth printhead is adjacent a paper path defined by the printer body and the contacts on the printhead cartridge are connected to the corresponding contacts on the printer body, the cradle having a fulcrum formation for engaging a complementary formation on the casing upon insertion of the cartridge; such that,the cartridge rotates into the operative position and the casing is a lever for pushing the contacts into engagement with the corresponding contacts on the printer body.
17. An inkjet printer according to claim 2 wherein the printhead cartridge has a casing that supports a pagewidth printhead, and the printer body has a cradle for holding the printhead cartridge in an operative position such that the pagewidth printhead is adjacent a paper path defined by the printer body, the cradle having a fulcrum formation for engaging a complementary formation on the casing upon insertion of the printhead cartridge so that the printhead cartridge rotates into the operative position; wherein,the cradle has a biased locating abutment to apply a compressive force for maintaining the printhead cartridge in the operative position and the casing has a structural member extending from the complementary formation for engaging the fulcrum formation; such that during use,the structural member extends from the locating abutment to the complementary formation and is aligned with the direction of the compressive force.
18. An inkjet printer according to claim 2 wherein the printhead cartridge has a pagewidth inkjet printhead structure with an array of nozzles for ejecting ink supplied by a plurality of the ink cartridges, each of the ink cartridges having one of the ink inlets respectively, and a plurality of resilient connectors for each of the ink inlets respectively, the resilient connectors forming part of the fluid path to the nozzles corresponding to each ink cartridge, the ink inlets and the resilient connectors being mounted in a docking frame for receiving the ink cartridges; such that, longitudinal expansion and contraction of the pagewidth printhead structure relative to the ink cartridge docking frame is accommodated by the resilient connectors.
19. An inkjet printer according to claim 18 wherein the docking frame is configured to receive five of the ink cartridges, the ink cartridges containing cyan, magenta, yellow, black and infra red ink respectively.
20. An inkjet printer according to claim 2 wherein the printhead cartridge has a pagewidth printhead and a maintenance station for engaging the printhead when not in use;the inkjet printer further comprises a maintenance station drive shaft for detachably engaging the maintenance station upon insertion of the printhead cartridge into the printer, the maintenance station drive shaft having an engagement formation at one end for engaging a complementary formation in the maintenance station; such that,when engaging the complementary formation, the engagement formation has limited axial displacement and limited transverse displacement. |
