Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-02-17
2001-02-20
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06190007
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS, IF ANY
None.
BACKGROUND OF THE INVENTION AND PRIOR ART
The present invention relates to the art of computer driven printers, particularly, color inkjet printers. Printers of this type have a printhead carriage which is mounted for reciprocal movement on the printer in a direction orthogonal to the direction of movement of the paper or other medium on which printing is to take place through the printer. The printer carriage of a color printer typically has four or more removable thermal ink jet printheads mounted thereon. Each of the printheads contains or is attached to a supply of ink and occasionally it is necessary to prime one or more printheads by creating a pressure differential to force ink to flow through the ink delivery orifices.
Printhead priming has previously been done by positioning a compliant seal around the nozzle plate of the printhead after the printhead carriage has been parked at a service station. In these systems, ink is drawn through the printhead nozzles by applying a negative pressure to the outside of the nozzle plates of the printheads to suck ink through the orifices. The source of the negative air pressure differential has been, among others, a collapsing air bellows or a remote pump connected by a fluid conduit. In these systems, the pressure is maintained by pressing a compliant cap against the surface surrounding the nozzles to create a chamber closed to the atmosphere but connected to the pressure source. The use of negative pressure to prime a printhead can have several disadvantages such as ink foaming, excessive waste ink and lack of precise control over the priming operation. Accordingly a system for printhead priming is required which does not rely upon negative pressure priming and by which a printhead can be primed in a controlled manner with minimal risk of system damage.
SUMMARY OF THE INVENTION
In its broadest aspects, the present invention provides a printhead carriage for an ink jet printer which includes a frame having at least one printhead stall therein, the improvement comprising: a printhead holddown cover connected to said frame for fastening said cover in a closed printhead holddown position relative to the frame, said cover having at least one fluid passageway therein for conducting fluid between at least one fluid port on said cover exposed to atmosphere and a fluid port in said printhead stall, said printhead stall fluid port being engageable with a fluid port on a printhead positioned in said stall to exchange fluid with said printhead.
The present invention further provides a printer which includes the moveable carriage of the preceding paragraph and at least one inkjet printhead in operative position in a stall on said carriage and further comprising:
a) a fluid pump having a fluid outlet for delivering fluid to said inkjet printhead, said pump outlet comprising a moveable outlet proximate an end of the path of carriage travel for engagement by said carriage to actuate said pump to deliver a controlled volume of said fluid to said printhead, and
b) a pump position actuator for moving said pump outlet to a selected position to connect said pump outlet to supply fluid under pressure to a selected fluid passageway in said cover and an associated printhead.
REFERENCES:
patent: 4853717 (1989-08-01), Harmon et al.
patent: 5027134 (1991-06-01), Harmon et al.
patent: 5592201 (1997-01-01), Lim
patent: 5614929 (1997-03-01), Dangelo et al.
patent: 5999203 (1999-12-01), Cane et al.
patent: 6012806 (2000-01-01), De Olazabal
de Santiago Sergio
Girones Xavier
Serra Antoni Murcia
Taylor Christopher C.
Hewlett-Packard Company Intellectual Property Administration
Le N.
Nghiem Michael
Roth & Goldman
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