Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2003-06-18
2004-09-07
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06786580
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention is directed to a regulator for regulating the flow of ink from an ink source to a print head in a printer; and, more particularly, to a regulator that is submersible within an ink reservoir and that operates relatively independent of the inlet ink pressure.
2. Background of the Invention
The flow of fluids through predetermined conduits has been generally been accomplished using a valve and/or a pressure source. More specifically, valves come in various shapes and sizes and include as a subset, check valves. These valves prevent the reversal of fluid flow from the direction the fluid passed by the valve. A limitation of check valves is that the volumetric flow of the fluid past the valve is controlled by the inlet side fluid pressure. If the inlet pressure is greater than the outlet pressure, the valve will open and fluid will pass by the valve; if not, the inlet fluid will be relatively stagnant and the valve will not open.
Inkjet printers must take ink from an ink source and direct the ink to the print head where the ink is selectively deposited onto a substrate to form dots comprising an image discernable by the human eye. Two general types of systems have been developed for providing the pressure source to facilitate movement of the ink from the ink source to the print head. These generally include gravitational flow system and pumping systems. Pumping systems as the title would imply create an artificial pressure differential between the ink source and the print head to pump the fluid from the ink source to the print head. Generally, these pumping systems have many moving parts and need complex flow control system operatively coupled thereto. Gravitational flow avoids many of these moving parts and complex systems.
Gravitational fluid flow is the most common way of delivering ink from an ink reservoir to a print head for eventual deposition onto a substrate, especially when the print head includes a carrier for the ink source. However, this gravitational flow may cause a problem in that excess ink is allowed to enter the print head and accumulate, being thereafter released or deposited onto an unintended substrate or onto one or more components of the inkjet printer. Thus, the issue of selective control of ink flow from a gravitational source has also relied upon the use of valves. As discussed above, a check valve has not unitarily been able to solve the problems of regulating ink flow, at least in part because the inlet pressure varies with atmospheric pressure, and when the valve is submerged, the pressure exerted by the fluid itself.
U.S. Pat. No. 6,422,693, entitled “Ink Interconnect Between Print Cartridge and Carriage”, assigned to Hewlett-Packard Company, describes an internal regulator for a print cartridge that regulates the pressure of the ink chamber within the print cartridge. The regulator design includes a plurality of moving parts having many complex features. Thus, there is a need for a regulator to regulate the flow of ink from an ink source to a print head that includes fewer moving parts, that is relatively easy to manufacture and assemble, that is submersible within an ink source without necessitating direct coupling to the atmosphere to properly function.
SUMMARY OF THE INVENTION
The invention is directed to a mechanical device providing control over the flow of a fluid from a fluid source to at least a point of accumulation. More specifically, the invention is directed to an ink flow regulator that selectively allows fluid communication between the ink source and the print head so as to supply the print head with ink, while substantially inhibiting the free flow through of print head. The invention comprises a pressurized chamber, generally exhibiting negative gauge pressure therewithin, having an ink flow inlet and an ink flow outlet. A seal is biased against the ink inlet to allow selective fluid communication between the interior of the pressurized chamber and an ink source. A flexible wall, acting as a diaphragm, is integrated with a chamber wall to selectively expand outwardly from and contract inwardly towards the interior of the chamber depending upon the relative pressure differential across the flexible wall. The pressure differential depends upon the pressure of the interior of the chamber verses the pressure on the outside of the flexible wall. Operability of the invention is not negated by having the invention partially submerged or fully submerged beneath a fluid, nor is operability inhibited by having a liquid or a gas contacting the exterior of the flexible wall.
As the flexible wall contracts inwardly toward the interior of the chamber, it actuates a lever. The lever includes a sealing arm and an opposing flexible arm, and pivots on a fulcrum. The sealing arm includes the seal biased against the ink inlet, while the flexible arm is angled with respect to the sealing arm and includes a spoon-shaped end contacting the flexible wall. As the flexible wall continues contracting inward, the flexible arm flexes without pivoting the lever until the force of the wall against the flexible arm is sufficient to overcome the bias biasing the sealing arm against the inlet. When the force against the lever is sufficient to overcome the bias, the lever pivots about the fulcrum to release the seal at the ink inlet, thereby allowing ink to flow into the chamber until the pressure differential is reduced such that the bias again overcomes the reduced push created by the inward contraction of the flexible wall.
It is noted that the invention is not a check valve, as the operation of the regulator is independent from the inlet pressure when the regulator is not submerged within a liquid, and minimally dependent upon inlet pressure when the regulator is submerged within a liquid. In other words, a check valve is wholly dependent upon the inlet pressure, whereas this system of the present invention provides a relatively small inlet cross sectional area in relation to the size and relative forces action upon the regulator system that effectively negates any variance in inlet pressure. Thus, increasing the inlet pressure does not affect the operation of the regulator.
It is a first aspect of the present invention to provide a print head and regulator assembly for a printer that includes: (a) a print head; (b) an ink source; and, (c) a regulator for regulating the flow of ink between the ink source and the print head, the regulator including: (i) a pressurized chamber having an ink inlet in fluid communication with the ink source, an ink outlet in fluid communication with the print head,an opening extending through a chamber wall, and a flexible film covering the opening, the flexible film having an inner surface facing an interior of the pressurized chamber and an outer surface in contact with a liquid; and, (ii) a lever including a flexible arm positioned in proximity to the inner surface of the flexible film and an opposing arm operatively coupled to a seal that closes the ink inlet when the lever is in a first position and opens the ink inlet when the lever is pivoted to a second position; where the lever is biased to the first position; where a higher pressure differential across the flexible film brings about a higher force acting upon the flexible arm to overcome the bias and pivot the lever to the second position opening the ink inlet; and where a lower pressure differential across the flexible film brings about a lesser force acting upon the flexible arm resulting in the lever succumbing to the bias and repositioning the seal at the first position, closing the ink inlet.
In a more detailed embodiment of the first aspect, the ink source is an ink reservoir, and the regulator is at least partially submerged within the ink reservoir and the liquid contacting the outer surface of the flexible film is ink within the ink reservoir.
In another more detailed embodiment, the operating pressure on the interior of the pressurized chamber is between about 5 centimeters water column negative pressure and
Gray Trevor Daniel
Komplin Steven Robert
Russell Matthew Joe
Lexmark International Inc.
Vo Anh T. N.
LandOfFree
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