Servicing system for an inkjet printhead
Inactive Publication Date: 2008-05-06
HEWLETT PACKARD DEV CO LP
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AI Technical Summary
Benefits of technology
[0016]The present invention accordingly provides an improved system for servicing a portion of a printhead of an inkjet printer of the type having a printhead reciprocally moved by a carriage, and a wiper positioned and adapted to move relative to the printhead in wiping contact therewith, to remove unwanted accumulations from a portion of the printhead to be cleaned when the printhead and the wiper are moved relative to each other by movement of at least one of the two elements consisting of the printhead and the wiper. The system includes a source of printhead wiping treatment fluid adapted to store and reliably dispense treatment fluid. A means adapted to transfer by direct contact a reproducible quantity of treatment fluid from the source of treatment fluid onto at least one of the said two elements (printhead and wiper) so as to be available to assist in wiping is provided. The system includes wiping the printhead by relatively moving the wiper and the printhead subsequent to placing the treatment fluid on at least one of these elements.
Problems solved by technology
During printing, stray droplets of ink, dust, paper fibers and other debris can accumulate around the nozzles on the orifice plate surface and interfere with the trajectory of subsequently ejected ink droplets, thereby affecting print quality.
However, the combination of small nozzles and quick-drying ink leaves the printheads susceptible to clogging, in this case not only from the dried ink and minute dust particles or paper fibers, but also from the solids within the inks themselves.
Further, this dried ink is more difficult to remove than previously used dye-based inks when dried.
These characteristics compound the problems affecting print quality mentioned above.
Unfortunately, the dispersant tends to form a tough film on the printhead orifice plate face as the ink “vehicle” or carrier component of the pigment-based ink evaporates.
Besides the debris accumulated on the printhead face from ink over-spray, paper crashes and printer priming for example, this dispersant film also attracts and binds paper dust and other contaminants as well as solids from the ink itself.
It has been recognized that this film, as well as ink residue and debris surrounding the printhead nozzles, is quite difficult to remove from the printhead.
This system is not always fully effective even with older, dye-based inks.
While this later scheme works well with some dye-based ink systems, in involves wasting ink that would otherwise be used for printing.
Furthermore, cleaning systems using ink drawn from the printhead do not work as well, generally speaking, with high-solids waterfast ink formulations.
These factors, for example, limit the effectiveness of this known cleaning process, and this is undesirable.
Also, with this system more ink residue collects on the wiper, and some of these accumulations can be pushed back into the nozzles of the printhead which can at least temporarily cause one or more nozzles not to fire properly, degrading print quality.
However, many problems associated with use of a treatment fluid have been identified.
Storage of the treatment fluid in adequate amounts for the life of the printer without leaking is problematic.
For example leaks can occur due to tipping the printer and pressure differentials due to a change in temperature or altitude during shipment.
Another problem recognized is application of treatment fluid to a printhead having undesirable accumulations of ink solids, dispersants, and other debris without contamination of the source of treatment fluid by such accumulations.
Consistent optimal cleaning effectiveness as well as print quality can be compromised by application of too little or too much treatment fluid.
Too little treatment fluid results in less effective residue removal allowing undesirable accumulation.
Too much treatment fluid can result in one or more nozzles being at least temporarily disabled due to excess treatment fluid being pushed into the nozzle by the wiper, or drawn into the nozzle by negative pressure associated with operation.
In sum there are many problems, including identifying optimal ways of applying treatment fluid to enhance wiping effectiveness, that have been identified but not resolved in known cleaning systems.
Method used
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[0067]With reference to FIG. 1 of the drawings, which are provided by way of exemplary illustration, and not by way of limitation, there is shown an embodiment of an inkjet printing mechanism, here shown as an inkjet printer 10, constructed in accordance with the present invention. Such printers may be used for printing for business reports, correspondence, desktop publishing, and the like, in an industrial, office, home or other environment. A variety of inkjet printing mechanisms are commercially available. For instance, some of these printing mechanisms that may embody the present invention include plotters, portable printing units, copiers, cameras, and facsimile machines, to name a few, but for convenience the concepts of the present invention are illustrated in the environment of an inkjet printer 10.
[0068]While it is apparent that the printer components may vary from model to model, the typical inkjet printer 10 includes a chassis 12 and a print medium handling system 14 for ...
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A wet-wiping printhead cleaning system for inkjet printer incorporating a wiper for wiping the printhead including a treatment fluid applicator configured for placing treatment fluid onto at least one element of the printhead and wiper elements involved in wiping the printhead orifice plate surface, the treatment fluid being placed on said at least one element by direct contact of the applicator, subsequently the wiper wipes the printhead, the treatment being available to enhance cleaning effectiveness, the treatment fluid lubricating the wiper so as to lengthen wiper service life and enhance wiping performance, as well as acting to render unwanted accumulations on the printhead more removable by wiping.
Description
RELATED APPLICATIONS[0001]This application is related to three other co-owned applications filed concurrently herewith, namely: U.S. patent application Ser. No. 08 / 747,855 filed on Nov. 13, 1996 entitled WET-WIPING PRINTHEAD CLEANING SYSTEM USING A TRANSFER ELEMENT, HP Docket No. 10961139; U.S. patent application Ser. No. 08 / 747,884 filed on Nov. 13, 1999 entitled WET-WIPING PRINTHEAD CLEANING SYSTEM USING A PRINTHEAD TREATMENT FLUID STORED IN A NON-FLOWABLE STATE, HP Docket No. 10961134; and U.S. patent application Ser. No. 08 / 747,883 filed Nov. 13, 1999 entitled WET-WIPING PRINTHEAD CLEANING SYSTEM USING A NON-CONTACT TECHNIQUE FOR APPLYING A PRINTHEAD TREATMENT FLUID, HP Docket No. 10961138.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to the cleaning of printheads in computer-driven printers of the type generally known as inkjet printers. More particularly, the invention relates to such cleaning in printers employing a “wiper” whic...
Claims
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CPCB41J2/16552
InventorRHOADS, WILLIAM WISTARJOHNSON, ERIC JOSEPHDROGO, FRANKFERRARO, JOHNMARTINSON, PAUL ELIOTCASTLE, STEVEN TODDMATTIS, ERIC STEPHEN
OwnerHEWLETT PACKARD DEV CO LP