RELATED APPLICATIONS 
       [0001]    The present application claims the priority under 35 U.S.C. 119(a)-(d) or (f) and under C.F.R. 1.55(a) of previous International Patent Application No.: PCT/US2008/065061, filed May 29, 2008, entitled “Cap for a Fluid Container Outlet”, which application is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Inkjet printers typically utilize a printhead that includes an array of orifices (also called nozzles) through which ink is ejected on to paper or other print media. One or more printheads may be mounted on a movable carriage that traverses back and forth across the width of the paper feeding through the printer. Alternatively, one or more printheads may be mounted on a stationary carriage, as in a page-wide printhead array. A printhead may be an integral part of an ink cartridge or part of a discrete assembly to which ink is supplied from a separate, often replaceable ink container. For printhead assemblies that utilize replaceable ink containers, it is desirable to keep the outlet from the ink container sealed during packaging, shipping and storage to prevent ink leaking from the container. 
     
    
     
       DRAWINGS 
         [0003]      FIGS. 1-4  are perspective views illustrating an ink container and shipping cap according to one embodiment of the disclosure.  FIGS. 1 and 2  show the ink container in an upright orientation indicating the orientation of the ink container if it were installed in a printer.  FIGS. 3 and 4  show the ink container upside down indicating an orientation of the ink container for removing the shipping cap. The shipping cap is partially exploded away from the container in  FIGS. 2 and 4 . 
           [0004]      FIG. 5  is a close-up perspective view of one embodiment of an outlet for an ink container such as the ink container shown in  FIGS. 1-4 . 
           [0005]      FIGS. 6 and 7  are perspective views showing the inside and outside, respectively, of one embodiment of a shipping cap for capping the outlet shown in  FIG. 5 . 
           [0006]      FIGS. 8 and 9  are section views taken along the lines  8 - 8  and  9 - 9  in  FIG. 6 . 
           [0007]      FIGS. 10 and 11  are section views corresponding to the sections shown in  FIGS. 8 and 9  showing the shipping cap of  FIGS. 6-7  in place on a container outlet. 
           [0008]      FIG. 12  is close-up perspective, partial section view showing a portion of the inside of the shipping cap of  FIGS. 6-7 . 
           [0009]      FIG. 13  is close-up perspective, partial section view showing a portion of the inside of a shipping cap according to another embodiment of the disclosure. 
           [0010]      FIG. 14  is a section view showing a portion of the inside of a shipping cap according to another embodiment of the disclosure. 
           [0011]      FIG. 15  is a plan view showing two shipping caps as they might be arranged in a bulk feeding device for assembly to an ink container. 
       
    
    
     DESCRIPTION 
       [0012]    Embodiments of the present disclosure were developed as part of an effort to design a protective cap that reliably seals the outlet of a replaceable inkjet printer ink container despite dimensional variations within the manufacturing tolerances for the cap and the container outlet, and throughout a range of environmental conditions likely to be experienced during packaging, shipping and storage. Exemplary embodiments of the disclosure will be described, therefore, with reference to a protective cap for a replaceable inkjet printer ink container. Embodiments of the disclosure, however, are not limited to inkjet ink containers. Other forms, details, and embodiments may be made and implemented. Hence, the following description should not be construed to limit the scope of the disclosure, which is defined in the claims that follow the description. 
         [0013]      FIGS. 1-4  are perspective views illustrating an ink container  10  and a protective cap  12  according to one embodiment of the disclosure.  FIGS. 1 and 2  show ink container  10  in an upright orientation indicating the orientation of container  10  if it were installed in a printer.  FIGS. 3 and 4  show ink container  10  upside down indicating an orientation of container  10  for removing cap  12 . Protective cap  12  is partially exploded away from container  10  in  FIGS. 2 and 4 . Referring to  FIGS. 1-4 , container  10  includes a housing  14  that forms an internal chamber  16  for holding ink. Ink may be held in chamber  16  in a foam block  18  or other suitable ink holding material. Ink flows from container  10  to a printhead or other downstream component through an outlet  20  at the bottom of housing  14 . Protective cap  12  is designed to keep outlet  20  sealed during packaging, shipping and storage to prevent ink leaking from container  10 . Cap  12  is commonly referred to as a ship cap or shipping cap. 
         [0014]      FIG. 5  is a close-up view of container outlet  20 .  FIGS. 6 and 7  are close-up views showing the inside and outside of shipping cap  12 . Referring first to  FIG. 5 , outlet  20  protrudes from a bottom part  22  of container housing  12 . In this embodiment of container outlet  20 , the outer surface  24  and rim  26  of outlet  20  are circular and the opening  28  into ink chamber  16  is oval. Thus, an inner, facing surface  30  of outlet  20  transitions from a circular outer part  32  at rim  26  to an oval inner part  34  at opening  28 . Accordingly, the slope of facing surface  30  varies between a steeper slope along the rounded ends of opening  28  at contour areas  36  and a more gradual slope along the straight sides of opening  28  at contour areas  38 . 
         [0015]    Referring now to  FIGS. 6 and 7 , ship cap  12  includes a comparatively rigid plastic shell  40  forming a body  42  and a handle  44  that extends out away from body  42 . A cavity  46  in body  42  is lined with a more flexible, elastomeric liner  48 . Cap  12  may be fabricated, for example, using a so-called “two shot” molding process in which shell  40  is molded first and then liner  48  is molded into shell  40 . Container outlet  20  fits into cavity  46  and seals against liner  48  as described in detail below. Cap  12  may be attached to container housing  14 , for example, by ultrasonically welding a series of posts  50  on cap  12  to housing bottom  22 . Posts  50  are positioned around the outlet receiving cavity  46 . Cap  12  is pressed on to outlet  20  and welded at posts  50 . Posts  50  are configured to retain cap  12  on container  10  with sufficient pressure to maintain the seal between liner  48  and outlet  20  while still allowing the user to easily remove cap  12  by twisting, as indicated by arrows  52  in  FIG. 7 . Shell handle  44  facilitates twisting cap  12  off container  10 . The number, size and position of posts  50  may be varied as desirable to achieve the dual purpose of maintaining sealing pressure and allowing easy removal. 
         [0016]      FIGS. 8 and 9  are section views of cap  12  taken along the lines  8 - 8  and  9 - 9  in  FIG. 6 .  FIGS. 10 and 11  are section views corresponding to the sections shown in  FIGS. 8 and 9  showing cap  12  in place on container outlet  20 .  FIG. 12  is close-up perspective, partial section view showing a portion of shipping cap liner  48 . Referring to  FIGS. 8-12 , liner  48  includes a sidewall  54  and an undulating floor  56  adjoining sidewall  54 . A pair of concentric depressions  58 ,  60  are formed in floor  56  on opposite sides of an annular ridge  62 . Outer depression  58  is configured as a groove formed along sidewall  54 . Inner surface  30  of outlet  20  along rim  26  engages the outer periphery of ridge  62  at outer groove  58  along a contact surface  64 , as shown in  FIGS. 10 and 11 . It is desirable to make outer groove  58  deep enough so that outlet rim  26  does reach the bottom of groove  58 , to help ensure full contact between outlet inner surface  30  and liner contact surface  64 . 
         [0017]    Inner depression  60  is configured as a shallow groove along the inner periphery of ridge  62 . Inner groove  60  allows ridge  62  to flex inward when outlet surface  30  is pressed into ridge contact surface  64 . In a conventional shipping cap seal, there is no such relief to the inside of the contact surface when the container outlet is pressed into the elastomeric seal. Elastomers are virtually incompressible. Thus, where no relief is provided, there may be little compliance between the container outlet and the elastomeric contact surface unless very high compression forces are applied and maintained, pressing the outlet into the contact surface. High compression forces, however, are not desirable (and may not be realistic) for small plastic parts like an ink container outlet and shipping cap. Thus, a conventional seal is subject to failure due to dimensional variations in, or deformation of, the outlet or cap (or both). Embodiments of the new seal, in which inner depression  60  provides an area of relief into which ridge  62  may flex, accommodate greater dimensional variation in the parts without high compression forces, while still maintaining a good seal. 
         [0018]    The extent to which ridge  62  may flex is determined largely by the shape of ridge  62 , the depth of inner depression  60  and the characteristics of the elastomer used to form liner  48 . Although the degree of flex desirable may vary depending on the particular capping implementation, it is expected that, for a typical ink container ship cap implementation using a thermoplastic elastomer, a Santoprene brand thermoplastic vulcanizate with a Shore A durometer of about 35 for example, the following geometries will provide a reliable seal at moderate compression forces (50 N or below, for example). 
         [0019]    Depth of inner depression  60 ˜0.4 mm (from the surface of floor  56 ). 
         [0020]    Width (radially) of inner depression  60 ˜1.0 mm. 
         [0021]    Height of ridge  62  above depression  60 ˜0.65 (˜0.25 mm above the surface of floor  56 ). 
         [0022]    As noted above, the slope of facing, inner surface  30  of outlet  20  varies between a steeper slope along the rounded ends of opening  28  at contour areas  36  and a more gradual slope along the straight sides of opening  28  at contour areas  38 . A sharper corner having a smaller corner radius (or other curve) on ridge  62  helps match the geometry of contact surface  64  to the steeper contour areas  36  for a better seal. Similarly, a more rounded corner having a larger corner radius (or other curve) on ridge  62  helps match the geometry of contact surface  64  to the less steep contour at areas  38  for a better seal. These varying corner radii are illustrated in the section views at gradual contour areas  38  shown in  FIGS. 8 and 10  and in the section views at steeper contour areas  36  shown in  FIGS. 9 and 11 . Referring to  FIG. 10 , outlet inner surface  30  inclines at a less steep angle φ along section line  8 - 8  in  FIG. 6 , which corresponds to outlet contour areas  38  in  FIG. 5 . Referring to  FIG. 11 , outlet inner surface  30  inclines at a steeper angle θ along section line  9 - 9  in  FIG. 6 , which corresponds to outlet contour areas  36  in  FIG. 5 . Accordingly, as best seen in  FIGS. 8 and 9 , a corner radius at contact surface  64  is greater at the locations corresponding to angle φ (r φ  in  FIG. 8 ) and smaller at the locations corresponding to angle θ (r θ  in  FIG. 9 ). The corner radius at any particular location around ridge contact area  64  will vary within the range r φ - r θ  according to the corresponding contour on outlet inner surface  30 . 
         [0023]    Referring to  FIGS. 6 ,  8 ,  9  and  12 , a series of alignment ribs  66  protrude from sidewall  54  above ridge  62  to help center outlet  20  on ridge  62 . The use of alignment ribs  66  is possible, and their benefits realized, because the seal is achieved fully at the interface between outlet inner surface  30  and contact surface  64 . That is to say, the seal does not depend on contact between outlet rim  26  (and/or outlet outer surface  24 ) and cap liner  48 . Thus, a series of four ribs  66  spaced even around sidewall  54 , for example, will help keep outlet  20  centered on, and sealed against, ridge  62  despite dimensional variations in the parts that may result from manufacturing tolerances. In an alternative embodiment shown in  FIG. 13 , a continuous alignment rib  68  extends all the way around sidewall  54 . A continuous rib  68  helps center outlet  20  on ridge  62  and provides a second contact surface  70  for sealing against outer surface  24  of outlet  20 . A continuous rib  68 , however, may generate suction sufficient to draw ink out of outlet  20  when cap  12  is removed from container  10 . Thus, a continuous rib  68  may not be desirable in some implementations for ship cap  12 . 
         [0024]      FIG. 14  illustrates another embodiment in which body  42  of shell  40  is configured to avoid the formation of knit lines when molding liner  48 . A “knit line” in an injection molded part is a tiny crack created when two separate flows of the elastomer meet within the mold and solidify along an interface between flows, instead of flowing completely together. Knit lines in the elastomeric liner material forming contact surface  64  may compromise the integrity of the seal, allowing leakage. Referring to  FIG. 14 , an annular ridge  70  is formed on an otherwise flat surface  72  at the bottom  74  of cavity  46  in shell body  42 . Ridge  70  forms a protruding ring under liner ridge  62 . In the embodiment shown, an inner part  76  of the triangular ridge  70  slopes up from bottom surface  72  at substantially the same angle as an inner part  78  of liner ridge  62 , and an outer part  80  is parallel to liner sidewall  54  (perpendicular to bottom surface  74 ). It has been observed that ridge  70  in shell body cavity  46  will reduce the risk of knit lines forming in ridge  62  at contact surface  64  compared with the stepped topography for cavity bottom  74  shown in  FIGS. 8-11 . 
         [0025]      FIG. 15  is a plan view showing two shipping caps  12  as they might be arranged in an assembly feed track  82  in a bulk feeding operation for assembly to an ink container  10 . It has been observed that cap handles that taper to a narrow end are prone to overlap one another and jam in a feed track  82 , requiring operator intervention to clear the jam. A T-shaped end  84  of shell handle  44  on each ship cap  12  helps prevent caps  12  from overlapping one another in track  82 , reducing the risk of a jam during automated part handling operations. 
         [0026]    As noted at the beginning of this Description, the exemplary embodiments shown in the figures and described above illustrate but do not limit the disclosure. Other forms, details, and embodiments may be made and implemented. The foregoing description, therefore, should not be construed to limit the scope of the disclosure, which is defined in the following claims.
In one embodiment a fluid container includes a housing having a chamber therein for holding a fluid and an outlet from the chamber; and a cap capping the outlet. The cap includes a contact surface thereon contacting an interior surface of the outlet and a void therein adjacent to the contact surface such that a portion of the cap underlying the contact surface may flex into the void.