Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-06-27
2002-11-12
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06478402
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method for cleaning a nozzle outlet surface on a print head of an ink jet printer, more specifically, by a cleaning head, the ink being wiped off the nozzle outlet surface by a doctor blade on the cleaning head and being sucked away by a vacuum generator connected to the cleaning head, and also relates to a device for cleaning a nozzle outlet surface on a print head of an ink jet printer by a cleaning head which, more specifically, includes a doctor blade, the cleaning head further having a vacuum generator connected thereto.
A problem which often occurs in ink jet printers is that ink residues and paper dust collect on the nozzle outlet surfaces, so that they have to be wiped off frequently.
For this purpose, a wiping device described in the published German Patent Document DE 40 00 454 C2 can be used. The wiping device described in this published document has only a single doctor blade, referred to therein as an upper lip.
It is possible that the doctor blade, as it sweeps over the nozzle outlet surface, does not pick up all the contaminants and residues which are to be removed. Consequently, the nozzle outlet surface must be wiped off many times with the doctor blade, so that the expenditure of time for the cleaning, and the time during which the ink jet printer is at a standstill, are markedly increased.
A further shortcoming of the wiping device described in the foregoing German document is apparent from the fact that a vacuum pump thereof sucks in a considerable flow of outside air through the suction hole thereof which is open to the surroundings, this flow of outside air not only causing a low efficiency of the device, but also opposing the sucking of the ink out of the interior of the nozzle.
The wiping device has a cleaning head that includes a carrier part connected to the vacuum pump and having the wiping lip inserted therein. In order to clean the nozzle outlet surface, the cleaning head is disposed above the latter. In the case of such an arrangement, no assurance is provided that, after the nozzle outlet surface has been cleaned, no ink will drip back from the cleaning head onto the nozzle outlet surface.
A print head, which is referred to as a printer carriage in the published German document and can be wiped off by the wiping device, is moved relative to the stationary wiping lip, so that the latter brushes or streaks over the nozzle outlet surface on the print head. Although such a construction may indeed be suitable for a lightweight printer carriage having a relatively small-area nozzle outlet surface with only a few nozzles, it is not suitable for a heavier print head. In order to print large printing-material formats at high printing speeds, a print head having a large-area nozzle outlet surface equipped with a relatively large number of nozzles is more suitable. However, such a print head is generally also comparatively heavy and, because of the mass moment of inertia thereof, requires a complex drive mechanism, a high drive power and a large free movement space, in order to be able to move the print head relative to the wiping lip.
The state of the prior art may be further ascertained from the published German Patent Document DE 197 04 003 A1, the published European Patent Document EP 0 389 481 B1 and U.S. Pat. No. 5,730,538.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method and a device for cleaning a nozzle outlet surface on a print head of an ink jet printer by which the nozzle outlet surface can be cleaned quickly and thoroughly.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method for cleaning a nozzle outlet surface on a print head of an ink jet printer by a cleaning head, the ink being wiped off the nozzle outlet surface by a doctor blade on the cleaning head and being sucked away by a vacuum generator connected to the cleaning head, which comprises sucking the ink out of the interior of at least one nozzle on the nozzle outlet surface, by forming with the cleaning head an evacuation chamber over the opening, applying vacuum to the evacuation chamber by the vacuum generator, and hermetically sealing off the evacuation chamber.
In accordance with another mode, the method of the invention includes effecting the sealing off of the evacuation chamber by the doctor blade by the engagement thereof with the nozzle outlet surface.
In accordance with a further mode, the method of the invention includes hermetically sealing off the evacuation chamber by an additional doctor blade on the cleaning head by the engagement of the additional doctor blade likewise with the nozzle outlet surface.
In accordance with another aspect of the invention, there is provided a device for cleaning a nozzle outlet surface on a print head of an ink jet printer by a cleaning head formed of a doctor blade and connected to a vacuum generator, the cleaning head comprising at least one additional doctor blade.
In accordance with another feature of the invention, the device includes an evacuation chamber formed between the doctor blades in the cleaning head and being subjectible to suction air and vacuum, respectively, applicable by the vacuum generator.
In accordance with a further feature of the invention, the doctor blades are arranged as seals for sealing off the evacuation chamber between the cleaning head and the nozzle outlet surface.
In accordance with an added feature of the invention, the device includes a motor for moving the cleaning head parallel to the nozzle outlet surface via a first mechanism and/or toward and away from the nozzle outlet surface via a second mechanism.
In accordance with an additional feature of the invention, the first mechanism is a flexible drive mechanism.
In accordance with yet another feature of the invention, the mechanism is a cam control.
In accordance with yet a further feature of the invention, the cleaning head is disposed underneath the nozzle outlet surface.
In accordance with yet an added feature of the invention, the cleaning head is connected to the print head via an ink circuit.
In accordance with yet an additional feature of the invention, the cleaning head has at least three doctor blades.
In accordance with a further aspect of the invention, there is provided an ink jet printer having a device for cleaning a nozzle outlet surface on a print head of the ink jet printer by a cleaning head formed of a doctor blade and connected to a vacuum generator, the cleaning head comprising at least one additional doctor blade.
In accordance with another feature of the invention, the ink jet printer comprises a printing module and a cleaning module, the modules being of compatible construction so that the cleaning module is combinable with the printing module when appropriate.
In accordance with an additional aspect of the invention, there is provided an offset and/or rotary printing machine integrated with the ink jet printer having at least one of the foregoing features.
In accordance with a concomitant aspect of the invention, there is provided an offset and/or rotary printing machine coupled for in-line operation with an ink jet printer having at least one of the foregoing features.
The term “ink” used in connection with the invention comprises both water-based inks and inks of a different composition, for example radiation-curing inks, so-called ultraviolet or UV inks, which can be printed by the ink jet printer.
The ink in the print head sometimes tends to form air bubbles, which collect in the corners within the print head and the nozzles.
An advantage offered by the method according to the invention is that these air inclusions can be removed from the nozzle orifices together with the ink, so that printing faults caused by the air inclusions are avoided. Also, as the nozzle outlet surface is squeegeed or doctored off, paper dust wiped into the nozzle orifice can be sucked reliably out of the nozzle orifice, via the evacuation chamber and the nozzle op
Barlow John
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Stemer Werner H.
LandOfFree
Method and device for cleaning a nozzle outlet surface on a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for cleaning a nozzle outlet surface on a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for cleaning a nozzle outlet surface on a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2931965