Abstract:
In one embodiment, a cartridge includes: a housing having a chamber therein for holding a fluid; a hole extending through the housing to the chamber; and a breachable membrane that, in an unbreached state, substantially closes the hole, the membrane resiliently configured such that, upon being breached, the membrane rebounds to a breached state only partially closing the hole.

Description:
[0001]    This application clams the benefit of U.S. Provision Patent Application Ser. No. 60/992,901 filed on 6 Dec. 2007, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    For some types of inkjet printer ink cartridges ink is introduced into the cartridge through one or more fill holes molded into the cartridge housing. Ink fill holes are often positioned at the top of the cartridge so that the holes may also function as vent holes for venting the ink holding chamber(s) within the housing. In one such ink cartridge, a “vent plug” is inserted into each fill hole after the cartridge is filled with ink. The vent plug substantially closes the fill hole, leaving just a small opening or gap for venting the ink chamber. Ink fill holes are typically quite small, about 1/10 inch in diameter in some cartridges, and the vent openings are significantly smaller. Accordingly, the vent plugs are also very small. Fabricating and installing the tiny vent plugs adds significantly to the cost of the ink cartridge. Also, problems are sometimes encountered fabricating and installing vent plugs due to the small size of the plugs. For example, particulate debris and deformed plugs can jam or otherwise disable the automated machinery used to make and install the plugs, causing costly downtime and repairs. 
     
    
     
       DRAWINGS 
         [0003]      FIG. 1  is a perspective view illustrating an ink cartridge having ink fill holes, according to one embodiment of the disclosure. 
           [0004]      FIG. 2  is an elevation section view of an ink fill hole from the cartridge of  FIG. 1 , according to one embodiment of the disclosure. 
           [0005]      FIG. 3  is a plan section view of the ink fill hole shown in  FIG. 2 , taken along the line  3 - 3  in  FIG. 2 . 
           [0006]      FIG. 4  is a detail section view of a portion of the ink fill hole shown in  FIG. 2 . 
           [0007]      FIG. 5  is an elevation section view of the ink fill hole shown in  FIG. 2  with an ink fill needle inserted into the hole breaking away the membrane at the bottom of the hole. 
           [0008]      FIG. 6  is an elevation section view of the ink fill hole shown in  FIG. 5  after the ink fill needle has been withdrawn from the hole. 
           [0009]      FIG. 7  is an elevation section view of the ink fill hole shown in  FIG. 2  with an ink fill needle inserted into the hole puncturing the membrane at the bottom of the hole. 
           [0010]      FIG. 8  is an elevation section view of the ink fill hole shown in  FIG. 7  after the ink fill needle has been withdrawn from the hole. 
           [0011]      FIG. 9  is an elevation section view of an ink fill hole from the cartridge of  FIG. 1 , according to a second embodiment of the disclosure. 
           [0012]      FIG. 10  is a plan section view of the ink fill hole shown in  FIG. 9  taken along the line  10 - 10  in  FIG. 9 . 
           [0013]      FIG. 11  is an elevation section view of the ink fill hole shown in  FIG. 9  with an ink fill needle inserted into the hole puncturing the membrane at the bottom of the hole. 
           [0014]      FIG. 12  is an elevation section view of the ink fill hole shown in  FIG. 11  after the ink fill needle has been withdrawn from the hole. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Embodiments of the disclosure were developed in an effort to provide an alternative to the use of vent plugs to close ink fill holes in an ink cartridge. Embodiments will be described with reference to an ink fill hole in a tri-color ink cartridge. Embodiments of the disclosure, however, are not limited to use with tri-color ink cartridges or to ink fill holes, but might also be used in other ink cartridges, other fluid cartridges or to close other openings in a cartridge. The example embodiments shown in the Figures and described below, therefore, illustrate but do not limit the scope of the disclosure. 
         [0016]    As used in this document: “membrane” means a thin sheet or layer covering an opening or separating two adjoining areas; and “plastic” means a moldable polymer. 
         [0017]      FIG. 1  is a perspective view illustrating a tri-color ink cartridge  10  that includes a housing  12  enclosing three ink holding chambers. An ink fill hole  14 ,  16 ,  18  extends through the top of housing  12  to a corresponding ink holding chamber. Only one ink holding chamber  20  is visible in  FIG. 1 , corresponding to fill hole  14 . Housing  12  may be formed as a single part or as two or more discrete parts affixed to one another. Although an ink cartridge housing such as housing  12  is typically formed by molding plastic into the desired configuration, other techniques or materials might also be used to form housing  12 . Ink is held in foam  22  or another suitable porous material in chamber  20 . Ink cartridge  10  also includes a printhead (not visible in  FIG. 1 ) located at the bottom of cartridge  10  below the ink holding chambers. The printhead includes an array of ink ejection nozzles through which drops of ink are ejected at the urging of thermal or piezoelectric “firing” elements in the printhead. A flexible circuit  24  carries electrical traces from external contact pads  26  to the firing elements. 
         [0018]    Ink cartridge  10  is just one example of a cartridge in which embodiments of the new hole closure may be implemented. Other examples include “free ink” cartridges in which there is no ink-holding material in some or all of the ink holding chambers and ink cartridges that are solely ink reservoirs (i.e., cartridges that do not include a printhead). 
         [0019]      FIG. 2  is an elevation section view illustrating one example embodiment of an ink fill hole  14  in the cartridge of  FIG. 1 .  FIG. 3  is a plan section view of fill hole  14  taken along the line  3 - 3  in  FIG. 2 . Referring to  FIGS. 2 and 3 , hole  14  is defined by a sidewall  28  that extends from a top end  30  at an exterior of housing  12  to a bottom end  32  at ink chamber  20  (ink chamber  20  is not shown in  FIGS. 2-3 ). The bottom of hole  14  is closed by a membrane  34  spanning hole  14 . In the embodiment shown, membrane  34  is integral to housing  12  and fully closes hole  14  until an ink fill needle is inserted into hole  14  and through membrane  34 , as described below, or until membrane  34  is otherwise breached. Referring now also to the detail view of  FIG. 4 , a first extent of the periphery  36  of membrane  34  is thinned at the junction with sidewall  28  to form a locally weaker part  38 . The thickness of membrane  34  remains fully intact along a second extent of periphery  36  to form a locally stronger part  40 . 
         [0020]    Thus, membrane  34  is configured to break away from sidewall  28  along weaker part  38  when an ink fill needle  42  is inserted into hole  14 , as shown in  FIG. 5 , and to rebound back toward the original, closed position at the urging of stronger part  40  when ink fill needle  42  is withdrawn from hole  14 , as shown in  FIG. 6 . Stronger part  40  forms a living hinge on which membrane  34  swings open upon the insertion of fill needle  42  and swings back upon the withdrawal of fill needle  42 . The mechanical characteristics of polyethylene terephthalate or other such plastics typically used for molding ink cartridges, along with the size and shape of stronger part  40  permit partially re-closing hole  14  upon withdrawal of fill needle  42 . It is desirable that hole  14  remain open enough to allow air to pass in and out of chamber  20  through hole  14  but not so open as to allow excessive evaporative losses from chamber  20 . Depending on the characteristics of fill needle  42  (e.g., size, shape/sharpness, and insertion force) the configuration of membrane  34  might also allow fill needle  42  to puncture membrane  34  upon insertion into hole  14 , as shown in  FIG. 7 . In the case of needle puncture, the entire periphery  36  of membrane  34  acts as a living hinge to return membrane  34  toward the original, closed position when ink fill needle  42  is withdrawn from hole  14 , as shown in  FIG. 8 . 
         [0021]    Referring again to  FIGS. 2-4 , in one example configuration in which ink fill hole  14  is about 0.23 inches long and 0.11 inches in diameter, typical for an ink cartridge  10  in  FIG. 1 , membrane  34  has a nominal thickness in the range of 0.005 inches to 0.015 inches. An ink fill needle used in an automated ink fill process typically exerts enough pressure to puncture a layer of molded polyethylene terephthalate up to about 0.040 inches thick. Thus, a plastic membrane  34  in the range noted above should be easily punctured in an automated ink fill process. Also, where it is desirable to weaken a membrane  34  to allow the membrane to break away upon insertion of the ink fill needle, membrane  34  may be beveled or otherwise thinned at weaker part  38  to a thickness in the range of 0.002 inches to 0.005 inches along about 270 degrees of its periphery  36 , leaving stronger part  40  along about 90 degrees of periphery  36 . In the example configuration shown in  FIGS. 2-4 , therefore, weaker part  38  is likely to fail significantly sooner than stronger part  40  and before membrane  34  is punctured but membrane  34  is also sufficiently thin to allow membrane puncture without damaging the fill needle or other fill tooling in the event the beveled weaker part  38  does not fail upon needle insertion. Also, in this example configuration, for an ink fill needle about 0.05 inches in diameter (about ½ the diameter of hole  14 ) membrane  34  will rebound to close at least 80% of a cross sectional area of hole  14   
         [0022]    In the embodiment shown in  FIGS. 9-12 , membrane  34  is configured for needle puncture only. Referring first to  FIGS. 9 and 10 , membrane  34  has a uniform thickness along its entire periphery  36 . Thus, membrane  34  is configured so that fill needle  42  punctures membrane  34  when an ink fill needle  42  is inserted into hole  14 , as shown in  FIG. 11 , and the entire periphery  36  of membrane  34  acts as a living hinge to return membrane  34  toward the original, closed position when ink fill needle  42  is withdrawn from hole  14 , as shown in  FIG. 12 . 
         [0023]    Although it is expected that membrane  34  will usually be molded as an integral part of cartridge housing  12 , it may be possible to form membrane  34  using other fabrication techniques. For example, membrane  34  might be formed with a secondary molding operation or by welding or staking a thin plastic sheet over hole  14 . It may be desirable in some ink cartridges to form membrane  34  at the top end  30  of hole  14 , or at some intermediate location between the top end  30  and the bottom end  32  of hole  14 . Also, while it is expected that membrane  34  will usually fully close hole  14  until breached, for some ink cartridges membrane  34  may substantially but not fully close hole  14  due to, for example, perforating the periphery of membrane  34 . Perforations may be desirable in any event to reduce or otherwise control the force needed to breach membrane  34 . Thus, the claims recite a membrane that “substantially closes” or a membrane “substantially closing” the hole to cover those cartridges in which a membrane in the “unbreached” or “formed” state may not always fully close the hole. 
         [0024]    The article “a” as used in the following claims means one or more. Thus, for example, “a weaker part” means one or more weaker parts and, accordingly, a subsequent reference to “the weaker part” refers the one or more weaker parts. 
         [0025]    The present disclosure has been shown and described with reference to the foregoing example embodiments. It is to be understood, however, that other forms, details and embodiments may be made without departing from the spirit and scope of the disclosure which is defined in the following claims.