Patent Publication Number: US-7219987-B1

Title: Tube coupling for ink jet cartridges

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to the art of ink cartridges for ink jet printers and, more particularly, to an improved coupling device for connecting an ink supply line to an ink cartridge in a continuous ink supply system. 
   Continuous ink refill systems for disposable ink jet cartridges are of course well known as shown, for example, in U.S. Pat. No. 5,469,201 to Erickson, et al. and U.S. Pat. No. 5,745,137 to Scheffelin, et al., both of which are incorporated herein by reference for background information. In such systems, basically, a cartridge is connected to an auxiliary ink supply reservoir by means of a flexible hose or tube, and during operation of the printing system, the tube is open to allow ink to flow from the auxiliary reservoir to the ink cartridge. During shipment or handling of the ink supply reservoir/cartridge system when it is outside the print machine, it is important that the connection of the tube to the cartridge be leak tight to preclude the leakage of ink within the cartridge assembly and/or onto exterior surfaces of the cartridge and any box or container in which the ink supply reservoir system is packaged for transportation and storage. Moreover, after installation in the printer, cleaning of the latter and/or the ink delivery system requires removal of the cartridge from the printer, whereby the orientation of the cartridge may change from its upright position in the printer to an inclined or prone position relative to an underlying support surface. Accordingly, it is again essential to have a leakproof connection between the tubing and cartridge to avoid leakage of ink therefrom. 
   Prior efforts to seal the connection between the supply tubing and cartridge include extending the tube into the cartridge through an opening in an outer wall of the cartridge and gluing the tube in the opening to provide a seal and strain relief for the tubing, as shown for example in the aforementioned patent to Erickson. In the patent to Scheffelin, et al., tubing is coupled to a cartridge through the handle thereof by means of slidably interengaging tubular components which provide a seal against leakage of ink from the cartridge. In the latter arrangement, it is possible to unintentionally separate the coupling components so as to expose ink in the cartridge to spillage. Moreover, at least upon continued usage, wear of the slidably interengaging components could result in creating a leakage path or paths from the interior to the exterior of the cartridge. A coupling of the ink supply tube to an opening into the cartridge by gluing the tubing in place is of course subject to the creation of a leakage path across the glue in response to lateral flexure of the supply tube relative to the cartridge and/or as a result of tension applied to the tubing in the direction outwardly or inwardly of the cartridge. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, a coupling is provided for connecting flexible ink supply tubing to an ink cartridge which optimizes achieving a leak-tight connection between the cartridge and coupling. The coupling has threaded interengagement with a wall component of the ink chamber in a cartridge such that the interengaging threads are in tension to optimize sealing engagement therebetween and, accordingly, a leak-tight joint between the ink chamber and the exterior of the cartridge. Preferably, the coupling component is provided with a flange adjacent a threaded stem of the coupling which engages the outer side of the wall component of the ink chamber to provide a further seal against leakage as the threaded interengagement between the stem and wall pulls the flange into tight engagement with the outer side of the wall. It is also preferred to provide for the coupling to have an outer leg parallel to the outer side of the cartridge for connection with the supply tubing. This configuration advantageously provides for the tubing to be closely adjacent the outer side of the cartridge and positioned for connection with the cartridge or an attachment thereto to provide strain relief for the tubing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing features of the present invention, and others, will in part be obvious and in part pointed out more fully hereinafter in conjunction with the written description of a preferred embodiment shown in the accompanying drawings in which: 
       FIG. 1  is a perspective view of the frame components of an ink cartridge having a supply tubing coupling in accordance with the invention mounted thereon; and, 
       FIG. 2  is a sectional elevation view of a portion of the frame components and coupling taken along Line  2 — 2  in  FIG. 1 . 
   

   DESCRIPTION OF A PREFERRED EMBODIMENT 
   Referring now in greater detail to the drawings, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting the invention,  FIG. 1  illustrates, in part, an ink cartridge  10  on which a tubing coupling  12  according to the invention is mounted. Cartridge  10  comprises an outer plastic housing  14  and an inner plastic frame  16 . While not shown, sheets of foil are attached to the opposite edges of the inner plastic frame to create a bag-like assembly that holds the cartridge ink, and the latter assembly is received within the outer plastic housing but is not attached thereto. Further, while not shown, metal side plates are assembled to the outer plastic housing to complete the outer enclosure for the cartridge. The latter ink cartridge construction is well known in the art. As will be appreciated from the cartridge structure, the area within inner frame  16  provides an ink chamber  18 , and in a continuous ink supply system for the cartridge ink is delivered from a reservoir through a flexible ink supply line  20  to coupling  12  and thence into chamber  18  through the coupling. Preferably, a strain relief arrangement is provided for tubing  20  and, in the embodiment herein illustrated, such strain relief is achieved by passing the tubing through an opening  22  through handle  24  of the cartridge. 
   As best seen in  FIG. 2 , coupling  12  is preferably L-shaped and includes an inner end or first leg  26  connected to upper portion  16   a  of inner frame  16  as set forth hereinafter, and outer end or second leg  28  extending parallel to outer wall portion  14   a  of housing  14 . A passageway  30  extends through the coupling for communicating the interior of chamber  18  with supply tube  20 . Outer end  28  of the fitting can be provided with any suitable arrangement for attaching tube  20  thereto including, as shown in  FIG. 2 , serrations  32  which frictionally interengage with tube  20 . Other connecting arrangements can be used with or as alternatives to serrations such as, for example, adhesive bonding and clamping devices. Preferably, coupling  12  includes an abutment  34  which, in the preferred embodiment is a radially outwardly extending flange on inner end  26  of the coupling, and the distal end  26   a  of the leg  26  is provided with threads  36  which threadedly interengage with the threads of a threaded opening  38  in wall portion  16   a  of inner frame  16 . Flange  34  has a planar inner surface  40  which facially engages against the planar outer surface of wall portion  16   a  and, in accordance with the invention, wall portion  14   a  of outer housing  14  is provided with an opening  42  diametrically larger than the diametric dimension of flange  34 , whereby the latter extends freely through opening  42  for the coupling to be attached directly to inner frame  14  of the cartridge. When coupling  12  is mounted on wall portion  16   a  by rotating the coupling to threadedly interengage end  26   a  in opening  38 , surface  40  of flange  34  is drawn into sealing interengagement with the outer side of wall portion  16   a  placing threads  36  and the threads of opening  38  in tension, thus optimizing sealing interengagement across the coupling in two areas, namely between surface  40  and wall portion  16   a  and between threads  36  and the threads of opening  38 . Distal end  26   a  of leg  26  extends through wall portion  16   a  so as to terminate within ink chamber  18  of the cartridge. 
   Coupling  12  can be mounted on an existing cartridge by counterboring wall portion  14   a  of outer housing  14  to provide opening  42  therethrough and then drilling and tapping wall portion  16   a  to accept threaded end  26   a  of the coupling member. 
   While considerable emphasis has been placed herein on the structure of a preferred embodiment of the invention, it will be appreciated that other embodiments as well as changes in the preferred embodiment can be made without departing from the principals of the invention. In particular in this respect, it will be appreciated that outer end  28  of the coupling could be coaxial with inner end  26  as opposed to being at right angles thereto. The latter configuration is preferred in that it provides for supporting the corresponding end of tube  20  close to the top of the cartridge and provide for a convenient intern connection with the cartridge handle to achieve strain relief for the tubing at the coupling. The foregoing and other changes as well as other embodiments of the invention will be suggested and/or obvious to those skilled in the art from the foregoing description, whereby it is to be distinctly understood that the descriptive matter herein is to be interpreted merely as illustrative of the present invention and not as a limitation and that it is intended to include other embodiments and all modifications of the preferred embodiment insofar as they come within the scope of the appended claims or the equivalents thereof.