Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-07-14
2001-07-03
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06254226
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to ink cartridges used for supplying liquid ink to a printhead in a thermal ink jet printing apparatus. Specifically, the present invention relates to structure and methods for filling and venting the ink tank of an ink supply cartridge in a thermal ink jet printing apparatus.
Thermal ink jet printing is well understood in the art. U.S. Pat. No. 5,997,121 describes several aspects of such printing.
In existing thermal ink jet printing, the printhead comprises one or more ink filled channels communicating with a relatively small supply chamber, or manifold, at one end, and having an opening at the opposite end, referred to as a nozzle. In current practical embodiments of drop on demand thermal ink jet printers, it has been found that the printers work most effectively when the pressure of the ink in the printhead nozzle is kept within a predetermined range of gauge pressures. Specifically, at those times during operation in which an individual nozzle or an entire printhead is not actively emitting a droplet of ink, it is important that a certain negative pressure, or “back pressure”, exist in each of the nozzles and, by extension, within the ink supply manifold of the printhead. The attributes of creating and maintaining such back pressure are described in the U.S. Pat. No. 5,289,212, the contents of which are incorporated herein by reference.
The ink is supplied to the printhead from an ink cartridge. The ink cartridge contains a supply of ink, and is typically configured to maintain the required negative pressure. The ink cartridge is typically a user-replaceable unit that mates with the printhead of the printing apparatus.
Before delivery to the user, the ink cartridge is filled with ink. Changes in the ambient environmental conditions (i.e., temperature, atmospheric pressure, etc.) after the cartridge is filled can cause challenges for the user. If the cartridge is completely sealed, the contents of the cartridge may be at a higher pressure than the ambient when the user unseals the cartridge to install it in the printhead. In that instance, ink may be forcefully and unpredictably ejected from the cartridge when the cartridge is unsealed.
SUMMARY OF THE INVENTION
A fluid cartridge, such as a cartridge for filling with ink for use in an ink jet printhead, comprises a wick chamber having outer walls, and an ink chamber, also having outer walls. An outlet opening extends through an outer wall of the wick chamber. A vent opening extends through an outer wall of the wick chamber. A fluid conduit connects the ink chamber and wick chamber. The outer walls of the ink chamber are formed to provide no fluid communication between the ink chamber and the ambient environment, except through the fluid conduit and the wick chamber.
In accordance with another aspect of the present invention, a method of filling a cartridge is provided. The cartridge comprises a housing defining a wick chamber and an ink chamber with a fluid conduit between the ink chamber and the wick chamber. The housing additionally contains wick material in the wick chamber, and has a fluid opening through the housing into the wick chamber. In accordance with the method of the present invention, an air gap is maintained between the fluid opening and the wick material, and ink is supplied through the fluid opening into the wick chamber until the ink flows through the fluid conduit into the ink chamber. The step of maintaining a gap between the fill tube fluid opening and the wick material comprises providing structure that prevents the wick material from contacting the fluid opening.
REFERENCES:
patent: 5289212 (1994-02-01), Carlotta
patent: 5875615 (1999-03-01), Ito et al.
patent: 5953030 (1999-07-01), Ishinaga et al.
patent: 5997121 (1999-12-01), Altfather et al.
patent: 06226390 (1996-04-01), None
Lengyel Dennis M.
Nguyen Hiep H.
Arthur David J.
Le N.
Vo Anh T. W.
Xerox Corporation
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