Abstract:
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.

Description:
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. 

   
     DRAWINGS 
       FIG. 1  is a perspective view of an ink pen assembly that includes a color ink pen with attached yellow, magenta and cyan ink supply cartridges. 
       FIG. 2  is a partial section view of the assembly of  FIG. 1  taken along the line  2 - 2  in  FIG. 1 . 
       FIG. 3  is a partial section view of the assembly of  FIG. 1  showing the ink supply cartridge detached from the ink pen. 
       FIG. 4  is a section view of the ink pen of  FIG. 1  taken along the line  4 - 4  in  FIG. 1 . 
       FIG. 5  is a detail perspective view showing a lid for an ink supply cartridge such as the cartridges shown in  FIGS. 1-3 . 
       FIGS. 6-8  are section views showing in more detail the vent seal in the cartridge of  FIGS. 2 and 3 . 
       FIGS. 9-10 ,  11 - 12 ,  13 - 14  and  15 - 16  are section views showing examples of other vent seals that might be used in an ink supply cartridge like the one shown in  FIGS. 2 and 3 . 
   

   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. 1  is a perspective view of an ink pen assembly  10  that includes a color ink pen  12  and ink supply cartridges  14 ,  16  and  18  attached to ink pen  12 . Cyan, magenta and yellow in cartridges  14 ,  16  and  18  are shown in  FIG. 1  as one example of the colors used in ink pen  12 .  FIG. 2  is a side elevation section view of ink pen assembly  10  taken along the line  2 - 2  through yellow supply cartridge  18  in  FIG. 1 .  FIG. 3  is similar to  FIG. 2  except that supply cartridge  18  is detached from ink pen  12 .  FIG. 4  is a partial front elevation section view showing the ink ejection nozzle area of ink pen  12 . The relative scale and dimensions of some of the features of assembly  10  shown in  FIGS. 2-4  are greatly adjusted and some conventional features well known to those skilled in the art of inkjet printing have been omitted for clarity. 
   Referring first to  FIGS. 1-3 , each supply cartridge  14 ,  16  and  18  fits into a receiver  20 ,  22  and  24  extending from housing  26  of ink pen  12 . Each cartridge  14 ,  16  and  18  includes a housing  28  that encloses an ink storage tank  30 , an outlet  32  and a vent  34 . A flat flange  36  extends to the rear of housing  28  to make it easier for a user to grasp a cartridge  14 ,  16  or  18  for installation and removal. Outlet  32  is positioned at one extreme of tank  30 , the lower right hand corner in the embodiment shown in  FIGS. 2 and 3 . Vent  34  is positioned at another extreme of tank  30 , the upper left hand corner in the embodiment shown in  FIGS. 2 and 3 . While the position of outlet  32  and vent  34  may vary depending on the particular configuration and/or placement of cartridge  14 ,  16  or  18 , it is expected that outlet  32  typically will be positioned at a lower extreme of tank  30  to allow as much ink as possible to flow out of tank  30  and vent  34  typically will be positioned at an upper extreme of tank  30  above the level of ink in tank  30 . 
   Supply cartridge housing  28  includes a body  38  and a lid  40 . Body  38  and lid  40  may be formed as discrete parts affixed to one another or as an integral unit. Vent  34  is formed as an opening in lid  40 . One example of a lid  40  is shown in  FIG. 5 . Referring now also to  FIG. 5 , vent  34  is exposed to the atmosphere through a circuitous tunnel  42 . In some applications for supply cartridge  28 , vent  34  may 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 vent  34 . Tunnel  42 , commonly referred to as a labyrinth, is formed by a recess  44  in the top  46  of lid  40  covered by a label or other suitable cover  48 . 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 in  FIGS. 2 and 3 , outlet  32  is sealed with an elastic membrane  50 . As shown in  FIG. 2 , when a supply cartridge  14 ,  16  or  18  is installed in a receiver  20 ,  22  or  24 , a needle  52  projecting from ink pen housing  26  pierces membrane  50  to provide a pathway for ink to flow from supply cartridge  14 ,  16  or  18  to ink pen  12 . A ball cork seal  53  seals supply cartridge vent  34 . 
   Referring to  FIGS. 2-4 , a print head  54  is located at the bottom of ink pen  12 . Print head  54  includes an orifice plate  56  with ink ejection orifices  58  and firing resistors  60  formed on an integrated circuit chip  62  positioned behind ink ejection orifices  58 . A flexible circuit  64  carries electrical traces from external contact pads (not shown) to firing resistors  60 . When ink pen  12  is installed in a printer, pen  12  is electrically connected to the printer controller through the contact pads. In operation, the printer controller selectively energizes firing resistors  60  through the signal traces in flexible circuit  64 . When a firing resistor  60  is energized, ink in a vaporization chamber  66  next to a resistor  60  is vaporized, ejecting a droplet of ink through orifice  58  on to the print media. Vaporization chamber  66  then refills with ink from ink reservoirs  70 ,  72  or  74  in preparation for the next ejection. The flow of ink through print head  54  is illustrated by arrows  68  in  FIG. 4 . Each ink reservoir  70 ,  72  and  74  can be resupplied with ink from the respective supply cartridge  14 ,  16  or  18  through needle  52  at inlet port  76  in each reservoir  70 ,  72  and  74 . Breaching vent seal  53  on a supply cartridge  14 ,  16  or  18  allows ink to flow from the supply cartridge  14 ,  16  or  18  into the respective reservoir  70 ,  72  or  74 . 
     FIGS. 6-8  illustrate one embodiment of a ball cork seal  53  in more detail. Referring to  FIGS. 6-8 , a ball  78  is pressed into a circular opening  80  that forms vent  34  in lid  40  of cartridge housing  28 . Opening  80  is defined by a sidewall  82  that includes a lead-in  84 , a ball seat  86  and a lead-out  88 . Lead-in  84  tapers down to a sharp upper edge  90  of ball seat  86 . A sharp upper edge  90  helps stop capillary travel of ink meniscus from tank  30  to tunnel  42 . Lead-out  88  tapers out from a sharp lower edge  92  of ball seat  86 . Opening  80  is configured to make the force needed to push ball  78  into ball seat  86  greater and the force needed to push ball  78  down out of ball seat  86  lesser. For example, the diameter of opening  80  at upper edge  90  is made smaller to make the force needed to push ball  78  past upper edge  90  fully into ball seat  86  greater and the diameter of opening  80  at lower edge  92  is made larger to make the force needed to push ball  78  past lower edge  92  out of ball seat  86  less than the force need to push ball  78  back past upper edge  90 . A sharp lower edge  92  also helps stop capillary travel of ink meniscus from tank  30  into ball seat  86 . Lead-out  88  is configured to squeeze ball  78  out of opening  80  once the diameter of ball  78  has passed lower edge  92  by, for example, allowing the lower part of sidewall  82  to flex as ball  78  is pushed out of seat  86 . A radiused lip (not shown) on the bottom of lead-out  88  helps reduce the meniscus force from any ink meniscus that forms. Outside wall  94  tapers down at lead-out  88  to make the exit cross-section of sidewall  82  weaker at lower edge  92  and lead-out  88 . 
   The face  94  of ball seat  86  is spherical with a diameter slightly smaller than the diameter of ball  78  to help ensure a good seal force from an interference fit between ball  78  and face  94 . Ball seat  86  is positioned so that ball  78  is just below the plane of top  46  of lid  40 . Ball cork seal  53  is breached to vent tank  30  by pressing down on cover  48  until ball  78  pops out of opening  80 , as shown in  FIGS. 7 and 8 . The relative geometries of ball  78  and the pertinent features of opening  80  are determined, at least in part, to minimize the length of the stroke needed to push ball  78  down and out of ball seat  86 . 
     FIGS. 9 and 10  illustrate another embodiment of a breachable seal  96  such as might be used to seal vent  34  in supply cartridges  14 ,  16  and  18 . Referring to  FIGS. 9 and 10 , seal  96  is constructed as a generally “dumbbell” shaped plug that includes a top flange  98  and a bottom flange  100  extending from a body  102 . Bottom flange  100  extends out from body  102  more than top flange  98  so that the force needed to push plug  96  into tank  30  is lower than the force need to push plug back out of opening  104  in lid  40 . 
     FIGS. 11 and 12  illustrate another embodiment of a breachable seal  106  such as might be used to seal vent  34  in supply cartridges  14 ,  16  and  18 . Referring to  FIGS. 11 and 12 , seal  106  is constructed as a weakened “break-out section”  108  of lid  40 . Break-out section  108  includes a post  110  and a narrow neck  112 . Post  110  extends to or near top  46  of lid  40  and is positioned generally at the center of section  108  surrounded by neck  112  (or between neck portions  112  if the neck is not continuous). Seal  106  is breached by pressing cover  48  into post  110  to break neck  112  and expose tank  30  to the atmosphere through tunnel  42 . 
     FIGS. 13 and 14  illustrate another embodiment of a breachable seal  114  such as might be used to seal vent  34  in supply cartridges  14 ,  16  and  18 . Referring to  FIGS. 13 and 14 , seal  114  is constructed as a weakened “break-out section”  116  of lid  40 . Break-out section  116  includes a post  118  and a narrow neck  120 . A screw  122  threaded into lid  40  over post  118  is used to breach seal  114 . Seal  114  is breached by turning screw  122  into post  118  to break neck  120  and expose tank  30  to the atmosphere through a tunnel  122  formed along the interior of lid  40 . 
     FIGS. 15 and 16  illustrate another embodiment of a breachable seal  126  such as might be used to seal vent  34  in supply cartridges  14 ,  16  and  18 . Referring to  FIGS. 15 and 16 , seal  126  is constructed as a perceivable label or other cover  128  over a tunnel  130  that extends away from opening  132  in lid  40 . Seal  126  is breached by piercing cover  128  to expose tank  30  to the atmosphere through tunnel  130 . A deeper part  134  of tunnel  130  may be formed at the desired location for piercing cover  128  as necessary or desirable to facilitate breaching cover  128 . 
   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.