Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-09-18
2002-12-10
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C134S021000
Reexamination Certificate
active
06491387
ABSTRACT:
BACKGROUND OF INVENTION
Ink jet recording assemblies have been used for decades to record indicia on a recording medium, such as paper. A typical ink jet recording assembly broadly includes a printer unit and an ink jet cartridge assembly operatively coupled with the printer unit. The cartridge assembly contain a quantity of ink for printing the indicia. In use, the printer unit receives a piece of paper and causes the cartridge assembly to move transversely across the paper between an extended position and a retracted, parked position to print ink on the paper in the form of indicia.
Ink jet cartridge assemblies commonly include a body having an ink reservoir and a head assembly. The head assembly includes an integrated circuit heater, a plurality of ink cups, and a plurality of nozzle openings formed through a nozzle plate. The nozzle openings are positioned beneath the ink cups for printing indicia.
Ink jet print cartridges assembly manufactured by various manufacturers includes a nozzle plate having numerous nozzle openings and additional air openings. The bleed air openings permit ink to be drawn into the head assembly and to the ink cups during use. The ink cups are configured to retain the ink by surface tension to prevent leakage of the ink through the nozzle openings.
The integrated circuit heater includes resistors positioned within the ink cups. The resistors are coupled with a source of electric energy and are kept at an EMF of 24 VDC. The ink cups retain the ink by surface tension until the source of electric energy causes the EMF to drop to about 12 VDC, which then causes the current to increase, heating the resistors. As the resistors are heated, the ink in the ink cups boils and is ejected through the nozzle openings for printing the indicia. The individual resistors may be selectively heated thousands of times per second for relatively precise ejection of ink resulting in relatively precise printing of indicia.
The process of heating and boiling the ink causes sediments and other material to become deposited in and around the nozzle openings and ink cups. As a result, the nozzle openings and ink cups eventually become sufficiently clogged so that the cartridge assembly is unusable. Dried ink is also deposited in and around the nozzle openings, clogging the openings.
Ink jet cartridge assemblies also utilize ink reservoirs to hold ink in an air tight chamber until being drawn into the print head assemblies. When ink is used and no further ink can be drawn to the print head assemblies ink residues remain in ink reservoirs which become sediment.
While several devices and methods are known to remove ink sediments and other debris from print head nozzle openings there appears to be a void related to cleaning the inside of sealed ink jet cartridge assemblies as well as ink paths and print head nozzle openings.
Several devices are known which inhibit the clogging of the nozzle openings. For example, it is known to provide a head washing device mounted on a printer unit for spraying water on the nozzle plate when the cartridge assembly is in the retraced, parked position. By washing the nozzle plate after each use, sediments and other deposited material are moved from the nozzle openings, increasing the operational life of the cartridge assembly. A cleaning solution has also been used to clean a nozzle plate when the cartridge assembly is in the parked position. This does not effect the inside aspects of the cartridge, including the ink reservoir foam pads.
Another known method and device which is known uses a source of steam. Exposing the print head nozzle openings to direct steam is claimed to soften sediments and other materials so they may be removed. On many cartridges, heat in excess of 160 degrees Fahrenheit will soften and damage the adhesive holding the nozzle plate to the print head assembly, thus rendering it useless. Again, this does not effect the inside aspects of the cartridge including the ink reservoir foam pads.
Another known method of cleaning a nozzle plate involves the use of gas such as air or nitrogen gas. Such gas is directed tangentially to the face of the nozzle plate once the cartridge assembly has returned to the parked position. The gas carries sediments and other deposited material away from the nozzle plate, thus increasing the operational life of the cartridge assembly. This does not effect the inside aspects of the cartridge including the ink reservoir foam pads and may disrupt delicate electronic assembly unites if sediment has hardened to them.
It is also known to provide a print head wiper positioned adjacent to the parked position of the cartridge assembly. As the cartridge assembly is returned to the parked position, the wiper removes sediment and other deposited material from the nozzle plate.
Once a cartridge assembly has reached the end of its operational life, either due to clogging of the nozzle openings or emptying of the ink reservoir, the cartridge assembly is removed from the printer unit and replaced by a fresh cartridge assembly. The spent cartridge assembly may then be returned to the manufacturer for recycling.
In a typical recycling process, the ink reservoir is emptied of any remaining ink, and the assembly is cleaned. Even when a cartridge assembly is used in conjunction with a head washing or cleaning device, some amount of sediment and other material will be deposited and hardened in and around the internal ink reservoir including foam pads, internal ink paths and the print head assembly during the operation of the cartridge assembly. Therefore, in a thorough recycling process, the internal ink reservoir including foam pads, internal ink paths and the print head assembly are to remove dried ink and other residue to permit fully operational cartridges following recycling.
Another method of cleaning cartridge assemblies includes the steps of positioning the nozzle plate in a cleaning solution for a short period of time, and wiping the plate to remove the sediments and other material. Once the nozzle plate is cleaned, the cartridge assembly is dried, refilled with ink and tested. Cartridge assemblies which do not meet certain predetermined standards of printing quality are discarded.
Although the cleaning methods available causes some of the sediments and other material deposited in and around the nozzle openings to be removed, many nozzle openings and ink cups remain sufficiently clogged so that the cartridge assemblies must be discarded. As a result, there is a significant and heretofore unsolved need to provide an improved method and apparatus of cleaning not only the nozzle plate of an ink jet cartridge assembly, but also the internal aspects of a cartridge assembly to remove sediments and other material deposited in and around the cartridge assembly which if not already at the nozzle openings, may later flow and “clot” the same and diminish or destroy cartridge performance.
BRIEF SUMMARY OF THE INVENTION
The present invention addresses the prior art problems noted above and provides significant advance in the state of the art of cleaning ink jet cartridge ink reservoir tank and foam pads, internal ink paths and print head including the nozzle plate assemblies. The present invention includes an improved method of cleaning an ink jet cartridge assembly and an apparatus for use in such a method.
The inventive method broadly combines the steps of preparing cartridges for optimum cleaning, using a simple vacuum chamber to fully impregnate a cartridge ink reservoir, including the foam pads therein, with cleaning solvent. Lowing the atmospheric pressure of heated solvent causes low temperature boiling action which internally agitates dried ink and other residue in ink reservoir foam pads, internal ink paths and the print head including nozzle plate assembly. Solution warmed at optimum temperature which fully impregnates otherwise sealed cartridge interior will also speed the return of dried ink and other residue to a liquid state for discharge.
Cartridges fully impregnated with solvent and ink residue and other sedim
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