Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-02-17
2001-04-24
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06220699
ABSTRACT:
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 broadcast aspects, the present invention provides a method of actuating a fluid pump in a printer to exchange fluid with an ink jet printhead without removing the printhead from a printhead carriage comprising the steps of:
a) providing a printhead carriage having at least one fluid conduit extending from a first end which is open to atmosphere to a second end;
b) positioning a printhead on said carriage, said printhead having a fluid port in fluid communication with said second end of said conduit;
c) moving said printhead carriage to a fluid exchange position to bring said first port of said conduit into fluid transferring engagement with a fluid port of a fluid pump; and
d) further moving said printhead carriage so as to actuate said fluid pump and to exchange a predetermined amount of fluid at a predetermined pressure through said conduit with said printhead.
The present invention further provides, in a printer which includes a moveable carriage having at least one inkjet printhead thereon, the improvement comprising: a fluid pump having a fluid outlet for delivering fluid to said inkjet printhead without removing the printhead from said printhead carriage, said pump outlet being positioned on said printer 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.
REFERENCES:
patent: 4853717 (1989-08-01), Harmon et al.
patent: 5592201 (1997-01-01), Lim
patent: 5614929 (1997-03-01), Dangelo et al.
patent: 5969731 (1999-10-01), Michael et al.
patent: 6012806 (2000-01-01), De Olazabal
Angulo Emilio
Girones Xavier
Johnson Eric Joseph
Lewis Richard H.
Serra Albert
Hewlett--Packard Company
Le N.
Nghiem Michael
Roth & Goldman
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