In one embodiment, a reservoir for holding a fluid includes a housing defining an enclosed chamber, the housing having a first opening therein at one part of the chamber and a second opening therein at a second part of the chamber above the first part of the chamber, a breachable seal sealing the second opening, and a circuitous tunnel exposing the chamber to the atmosphere through the second opening if the seal is breached.

BACKGROUND

Some inkjet printing systems utilize replaceable ink supply cartridges positioned or carried adjacent to the ink pens to resupply the pens with ink. An ink supply cartridge must be vented to allow ink to flow from the cartridge into the ink pen. The vent on the supply cartridge should be sealed until the ink pen is intentionally resupplied with ink to prevent the stored ink from evaporating or spilling.

DESCRIPTION

Embodiments of the present invention were developed in an effort to provide a breachable seal suitable for use sealing the vent on a replaceable ink supply cartridge. Some embodiments of the invention, therefore, will be described with reference to inkjet printing and ink pens. An ink pen is also commonly referred to as an ink cartridge, a print cartridge or an inkjet print head assembly. Embodiments of the invention, however, are not limited to use in inkjet printing, ink pens or with ink. Rather, embodiments of the invention may be used in any application or environment which might benefit from such a seal. The exemplary embodiments shown in the figures and described below illustrate but do not limit the invention. Other forms, details, and embodiments may be made and implemented. Hence, the following description should not be construed to limit the scope of the invention, which is defined in the claims that follow the description.

FIG. 1is a perspective view of an ink pen assembly10that includes a color ink pen12and ink supply cartridges14,16and18attached to ink pen12. Cyan, magenta and yellow in cartridges14,16and18are shown inFIG. 1as one example of the colors used in ink pen12.FIG. 2is a side elevation section view of ink pen assembly10taken along the line2-2through yellow supply cartridge18inFIG. 1.FIG. 3is similar toFIG. 2except that supply cartridge18is detached from ink pen12.FIG. 4is a partial front elevation section view showing the ink ejection nozzle area of ink pen12. The relative scale and dimensions of some of the features of assembly10shown inFIGS. 2-4are greatly adjusted and some conventional features well known to those skilled in the art of inkjet printing have been omitted for clarity.

Referring first toFIGS. 1-3, each supply cartridge14,16and18fits into a receiver20,22and24extending from housing26of ink pen12. Each cartridge14,16and18includes a housing28that encloses an ink storage tank30, an outlet32and a vent34. A flat flange36extends to the rear of housing28to make it easier for a user to grasp a cartridge14,16or18for installation and removal. Outlet32is positioned at one extreme of tank30, the lower right hand corner in the embodiment shown inFIGS. 2 and 3. Vent34is positioned at another extreme of tank30, the upper left hand corner in the embodiment shown inFIGS. 2 and 3. While the position of outlet32and vent34may vary depending on the particular configuration and/or placement of cartridge14,16or18, it is expected that outlet32typically will be positioned at a lower extreme of tank30to allow as much ink as possible to flow out of tank30and vent34typically will be positioned at an upper extreme of tank30above the level of ink in tank30.

Supply cartridge housing28includes a body38and a lid40. Body38and lid40may be formed as discrete parts affixed to one another or as an integral unit. Vent34is formed as an opening in lid40. One example of a lid40is shown inFIG. 5. Referring now also toFIG. 5, vent34is exposed to the atmosphere through a circuitous tunnel42. In some applications for supply cartridge28, vent34may be exposed to the return side of an ink delivery system and allow pumping, remote venting, bleeding or pressurization as well as recirculation. Hence, direct venting to the atmosphere is just one example for vent34. Tunnel42, commonly referred to as a labyrinth, is formed by a recess44in the top46of lid40covered by a label or other suitable cover48. Labyrinths, which are well known in the art of inkjet printing, are commonly used for venting ink pens to slow the rate of evaporation. In the embodiment shown inFIGS. 2 and 3, outlet32is sealed with an elastic membrane50. As shown inFIG. 2, when a supply cartridge14,16or18is installed in a receiver20,22or24, a needle52projecting from ink pen housing26pierces membrane50to provide a pathway for ink to flow from supply cartridge14,16or18to ink pen12. A ball cork seal53seals supply cartridge vent34.

Referring toFIGS. 2-4, a print head54is located at the bottom of ink pen12. Print head54includes an orifice plate56with ink ejection orifices58and firing resistors60formed on an integrated circuit chip62positioned behind ink ejection orifices58. A flexible circuit64carries electrical traces from external contact pads (not shown) to firing resistors60. When ink pen12is installed in a printer, pen12is electrically connected to the printer controller through the contact pads. In operation, the printer controller selectively energizes firing resistors60through the signal traces in flexible circuit64. When a firing resistor60is energized, ink in a vaporization chamber66next to a resistor60is vaporized, ejecting a droplet of ink through orifice58on to the print media. Vaporization chamber66then refills with ink from ink reservoirs70,72or74in preparation for the next ejection. The flow of ink through print head54is illustrated by arrows68inFIG. 4. Each ink reservoir70,72and74can be resupplied with ink from the respective supply cartridge14,16or18through needle52at inlet port76in each reservoir70,72and74. Breaching vent seal53on a supply cartridge14,16or18allows ink to flow from the supply cartridge14,16or18into the respective reservoir70,72or74.

FIGS. 6-8illustrate one embodiment of a ball cork seal53in more detail. Referring toFIGS. 6-8, a ball78is pressed into a circular opening80that forms vent34in lid40of cartridge housing28. Opening80is defined by a sidewall82that includes a lead-in84, a ball seat86and a lead-out88. Lead-in84tapers down to a sharp upper edge90of ball seat86. A sharp upper edge90helps stop capillary travel of ink meniscus from tank30to tunnel42. Lead-out88tapers out from a sharp lower edge92of ball seat86. Opening80is configured to make the force needed to push ball78into ball seat86greater and the force needed to push ball78down out of ball seat86lesser. For example, the diameter of opening80at upper edge90is made smaller to make the force needed to push ball78past upper edge90fully into ball seat86greater and the diameter of opening80at lower edge92is made larger to make the force needed to push ball78past lower edge92out of ball seat86less than the force need to push ball78back past upper edge90. A sharp lower edge92also helps stop capillary travel of ink meniscus from tank30into ball seat86. Lead-out88is configured to squeeze ball78out of opening80once the diameter of ball78has passed lower edge92by, for example, allowing the lower part of sidewall82to flex as ball78is pushed out of seat86. A radiused lip (not shown) on the bottom of lead-out88helps reduce the meniscus force from any ink meniscus that forms. Outside wall94tapers down at lead-out88to make the exit cross-section of sidewall82weaker at lower edge92and lead-out88.

The face94of ball seat86is spherical with a diameter slightly smaller than the diameter of ball78to help ensure a good seal force from an interference fit between ball78and face94. Ball seat86is positioned so that ball78is just below the plane of top46of lid40. Ball cork seal53is breached to vent tank30by pressing down on cover48until ball78pops out of opening80, as shown inFIGS. 7 and 8. The relative geometries of ball78and the pertinent features of opening80are determined, at least in part, to minimize the length of the stroke needed to push ball78down and out of ball seat86.

FIGS. 9 and 10illustrate another embodiment of a breachable seal96such as might be used to seal vent34in supply cartridges14,16and18. Referring toFIGS. 9 and 10, seal96is constructed as a generally “dumbbell” shaped plug that includes a top flange98and a bottom flange100extending from a body102. Bottom flange100extends out from body102more than top flange98so that the force needed to push plug96into tank30is lower than the force need to push plug back out of opening104in lid40.

FIGS. 11 and 12illustrate another embodiment of a breachable seal106such as might be used to seal vent34in supply cartridges14,16and18. Referring toFIGS. 11 and 12, seal106is constructed as a weakened “break-out section”108of lid40. Break-out section108includes a post110and a narrow neck112. Post110extends to or near top46of lid40and is positioned generally at the center of section108surrounded by neck112(or between neck portions112if the neck is not continuous). Seal106is breached by pressing cover48into post110to break neck112and expose tank30to the atmosphere through tunnel42.

FIGS. 13 and 14illustrate another embodiment of a breachable seal114such as might be used to seal vent34in supply cartridges14,16and18. Referring toFIGS. 13 and 14, seal114is constructed as a weakened “break-out section”116of lid40. Break-out section116includes a post118and a narrow neck120. A screw122threaded into lid40over post118is used to breach seal114. Seal114is breached by turning screw122into post118to break neck120and expose tank30to the atmosphere through a tunnel122formed along the interior of lid40.

FIGS. 15 and 16illustrate another embodiment of a breachable seal126such as might be used to seal vent34in supply cartridges14,16and18. Referring toFIGS. 15 and 16, seal126is constructed as a perceivable label or other cover128over a tunnel130that extends away from opening132in lid40. Seal126is breached by piercing cover128to expose tank30to the atmosphere through tunnel130. A deeper part134of tunnel130may be formed at the desired location for piercing cover128as necessary or desirable to facilitate breaching cover128.

As noted at the beginning of this Description, the exemplary embodiments shown in the figures and described above illustrate but do not limit the invention. Other forms, details, and embodiments may be made and implemented. Therefore, the foregoing description should not be construed to limit the scope of the invention, which is defined in the following claims.