Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2003-06-18
2004-09-28
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06796644
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 relatively independent upon the inlet pressure, such that the functionality of the regulator is relatively independent of the inlet pressure of the ink source.
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 discemable 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, and that does not necessitate 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.
As the flexible wall contracts inwardly towards 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 aspect 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. In other words, a check valve is 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 regulator adapted to regulate the throughput of an ink between an ink source and a print head, the regulator comprising: (a) a pressurized chamber including an ink inlet in fluid communication with the ink source, an ink outlet in fluid communication with the print head, and at least one flexible wall; and, (b) a lever including a flexible arm extending along a portion of the flexible wall and an opposing arm operatively coupled to a seal biased to close the ink inlet when the lever is in a first position and to open the ink inlet to allow fluid communication between the ink inlet and the pressurized chamber when the lever is pivoted to a second position; where a lower pressure differential across the flexible wall causes the flexible wall to actuate the flexible arm, pivoting the lever to the first position (inlet closed), where a higher pressure differential across the flexible wall causes the flexible wall to actuate the flexible arm to pivot the lever to the second position (inlet open), and where a pressure change from the lower pressure differential to the higher pressure differential across the flexible wall causes the flexible wall to actuate and flex the flexible arm without causing the lever to pivot.
In a more detailed embodiment of the first aspect, the lever includes a fulcrum positioned in-between the seal and the flexible arm. In another more detailed embodiment, the lever is located at least partly within the pressurized chamber. In yet another more detailed embodiment, the exterior flexible wall directly contacts the flexible arm. In a further detailed embodiment, the exterior flexible wall comprises a polymer film. In still a further more detailed embodiment, the exterior flexible wall is operatively mounted to the exterior of the pressurized chamber over a hole extending through a wall of the pressurized chamber. In yet a further more detailed embodiment, the pressurized chamber comprises a cap and a body. In another detailed embodiment, the ink inlet and the ink outlet spatially oppose one another. In yet another more detailed embodiment, an exterior surface of the exterior flexible wall is exposed to a
Anderson, Jr. James D.
Davis Gerald F.
Fowler John R.
Gray Trevor D.
Greer David E.
Lexmark International Inc.
Taft, Stettinius & Hollister, LL
Vo Anh T. N.
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