Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-09-29
2001-07-03
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000
Reexamination Certificate
active
06254216
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to ink jet printing in general and to continuous jet printers in particular. Such devices are well-known in this art and are used in industrial and commercial applications to print indicia on various product surfaces which are usually moving on a conveyor system. The indicia may contain useful information such as date codes, plant identification information and the like. Such printers are subject to long periods of continuous use and must be highly reliable. Nevertheless, at periodic intervals, it is necessary to clean the printhead which is usually located a distance from the printer electronics and ink supply. The printhead is connected to the printer system by an umbilical cord which contains the electronics, ink supply and ink return lines.
In continuous ink jet devices high voltage is used to electrostatically deflect charged ink drops onto the substrate to be marked. Uncharged drops are directed to a gutter which returns them to the ink reservoir for reuse. Typical ink jet systems of this type are disclosed in U.S. Pat. No. 3,683,396 assigned to the present assignee. Over time, the ink drops generate small particles, or ink mist, which when combined with dust, et cetera, may be electrostatically attracted to the high voltage deflection plates, charge electrode and related components contained within the printhead. This results in unwanted build up on the printhead components and, over time, degrades the quality of the printing by distorting the electric field, impeding the projection of the drops or causing the drops to be misdirected. For this reason, the printhead must be cleaned periodically.
Presently, when an ink jet printer is shut down at the end of a shift, or displays degraded printing operation, the printhead is manually disassembled and cleaned. This requires a skilled operator who removes the printhead cover and usually places the printhead mechanism consisting of a nozzle, charge electrode, deflection electrodes and gutter assembly in a special cleaning tray. He then sprays the printhead with a compatible solvent for cleaning, removes the solvent and dissolved ink and then drys the components, either by manually wiping them or blowing compressed air on them. Obviously, this manual operation is labor intensive, requiring skilled personnel to accomplish the task in a miniaturized, highly specialized electronic component and disposal of contaminated cleaning solvent. Incorrect cleaning techniques can lead to damage to the printhead or improper printing operation.
According to the invention, the need for manual cleaning is eliminated. Cleaning of the printhead components is accomplished automatically, in place, without disassembly of the printhead. This avoids exposing the technician to the hazardous fluids and the printhead remains sealed protected from handling damage and the environment which may exist at the point of its use. Furthermore, the automatic cleaning system of the present invention is relatively low in cost and requires little modification to existing printhead designs.
It is accordingly an object of the present invention to provide an automatic cleaning system for an ink jet printhead which eliminates the need for manual disassembly and cleaning of the printhead components.
It is a further object of the invention to provide a printhead which includes means for sealing and unsealing the printhead aperture through which ink normally exits to permit the printhead to be flooded with cleaning fluid (solvent). Solvent may then be introduced to the printhead and agitated either mechanically or with air to ensure contact of the solvent with dried ink and dust which may be deposited on the components. Thereafter the solvent is removed along with the material dissolved therein, all without the need for disassembling the printhead.
It is a further object of the invention to provide an ink jet printhead shutter which may be pneumatically operated to seal and unseal the printhead opening through which ink normally exits.
It is a further object of the invention to provide a printhead which can be selectively sealed so that a cleaning fluid can be introduced therein to clean the components. These and other objects of the invention will be apparent from the remaining portion of the specification.
SUMMARY OF THE INVENTION
A printhead structure includes an end plate at one end having a slot through which ink may be ejected during normal operation. Components including electrical parts are contained in the printhead behind the slot and within a sealable compartment. These components include a nozzle face, a charge electrode which applies a charge to selected ink drops exiting the nozzle, deflection electrodes and the collector for uncharged drops. In operative relation to the slot through which drops leave the printhead is a pneumatically inflatable tube or membrane. During normal operation of the printhead, the tube is deflated. For automatic cleaning, the tube is inflated, hermetically sealing the slot. Cleaning fluid such as make-up ink solvent is directed into the printhead compartment where it floods the components contained therein. Thereafter, mechanical vibration or air pressure can be used to agitate the cleaning fluid to ensure effective removal of dried ink which, over time, accumulates on the printhead components. Thereafter, the cleaning fluid is removed from the printhead via drain lines after which the tubular member is deflated. The printhead may then sit idle until the components therein are dry. Heated or unheated air may be introduced, or an electric strip heater may be used, to expedite drying of the components. Normal printing operation may resume thereafter.
REFERENCES:
patent: 4425934 (1984-01-01), Scheffer
patent: 4591870 (1986-05-01), Braun et al.
patent: 5459497 (1995-10-01), Manning et al.
patent: 5753049 (1998-05-01), Ihara et al.
patent: 5825380 (1998-10-01), Ichizawa et al.
patent: 000361393 (1990-04-01), None
patent: 0 424 008 (1991-04-01), None
patent: 002618728 (1989-02-01), None
patent: WO 093017867 (1993-09-01), None
patent: 57-27757 (1980-02-01), None
patent: 355109666 (1980-08-01), None
patent: 57-27757 (1982-02-01), None
patent: 58-42467 (1983-03-01), None
patent: 58-194577 (1983-11-01), None
patent: 60-023048 (1985-02-01), None
patent: 63-087241 (1988-04-01), None
patent: 4-039055 (1992-02-01), None
patent: 4-53753 (1992-02-01), None
patent: 04053753 (1992-02-01), None
patent: 07089092 (1995-04-01), None
patent: 7-314703 (1996-12-01), None
Arway George
Eremity Frank
Murad George
Le N.
Marconi Data Systems Inc.
Nguyen Lamson D.
Piper Marbury Rudnick & Wolfe
LandOfFree
Clean-in place system for an ink jet printhead does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Clean-in place system for an ink jet printhead, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Clean-in place system for an ink jet printhead will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2491135