Patent Publication Number: US-2006007278-A1

Title: Ink delivery system for the continuous refill of ink jet cartridges

Description:
BACKGROUND OF THE INVENTION  
      This invention relates to the art of ink jet printers and, more particularly, to an ink delivery system for the continuous refill of disposable ink jet cartridges.  
      Disposable ink jet cartridges are of course well known and are designed to operate for a useful life during which the head elements will function appropriately a very high percentage of the time during the life of the cartridge. To insure high performance, such cartridges have a predetermined amount of ink contained within the cartridge, and the amount of ink in the cartridge is a function of the quantity of printing that the printhead elements can do before failing to function at the high performance level. Once the ink in the cartridge is used, the cartridge is discarded. Most often, when such a cartridge runs out of ink the printhead is still adequately functional, whereby discarding the cartridge is wasteful. Moreover, the necessity to frequently replace inkjet cartridges is both time and labor intensive as well as expensive from the standpoint of product usage.  
      Systems have been provided heretofore for refilling ink jet cartridges in order to prolong the life thereof. These systems have included the manual refilling of cartridges, the refilling of cartridges through the use of systems of valves and pumps, as shown for example in Patent 4,680,696 to Ebinuma, et al., and continuous ink refill systems such as shown, for example, in patents 4,831,389 to Chan, 5,159,348 to Dietl, et al., and 5,469,201 to Erickson, et al. In a system such as that to which the present invention is directed, ink is continuously supplied to a cartridge from a remotely located ink reservoir through flexible tubing and wherein the reservoir is located in the printer below the cartridge and ink is drawn into the cartridge from the reservoir by a slight vacuum that is created as the ink within the cartridge is depleted. The reservoir is positioned below the cartridge to prevent flooding which can occur if the bag is positioned above the cartridge such that the head pressure of the ink in the supply line causes ink to be forced out of the cartridge nozzles and onto the surface of the nozzle plate. Such excess ink can adversely effect or even block the firing of the cartridge jet. At the same time, if the remote ink supply is positioned too far below the cartridge, the vacuum within the cartridge will not be sufficient to pull the ink into the cartridge from the reservoir. Accordingly, there is a fairly narrow operating window for the position of the reservoir relative to the cartridge. Since all of the ink in the reservoir must fall within the operating window, the size of the reservoir can be severely limited. Other concerns exist with respect to maximizing the utilization of space for the reservoir and maximizing the quantity of the volume of ink therein which is delivered or withdrawn from the reservoir. Moreover, in the systems heretofore provided, the connection of the supply tubing to the cartridge does not optimize protection of the latter from becoming disconnected from the cartridge during handling and/or is not routed relative to the cartridge so as to preclude interference with manipulation of the cartridge during insertion and removal thereof from a printer.  
     SUMMARY OF THE INVENTION  
      According to the present invention, an ink delivery system for the continuous refilling of an ink jet cartridge is provided which advantageously minimizes and/or overcomes the foregoing and other disadvantages encountered in connection with the use of such systems heretofore available. More particularly in this respect, a delivery system according to the present invention includes an ink reservoir in the form of a bag of flexible plastic sheet material having a structure which provides for containing a desired volume of ink for a given application and for optimizing depletion of the volume of ink from the bag during use such that a minimum amount of ink is left in the bag. Moreover, the structure provides a thin profile for the bag and thus a small head height variation over the life of the bag from the full to the empty condition thereof. In particular in this respect, the bag, when filled with ink, has length, width and height dimensions which provide an Aspect Ratio which, preferably, is in excess of four. The Aspect Ratio is the smaller of the length and width dimensions divided by the height. Accordingly, for example, if the bag has a length of 8 inches, a width of  3⅜ inches, and a height when filled of  3/4 inch the Aspect Ratio for the bag is 4.5. The low profile provided by an Aspect Ratio greater than four maximizes the quantity of ink delivered from the bag and, thus, minimizes ink loss through non-use. With respect to depleting the ink from the bag during use, the flexible sides of the bag collapse together as the bag is emptied and, as they collapse together, a thin channel is formed which permits the ink to flow by capillary action from all areas of the bag to the exit port thereof. The capillary action increases as the ink is depleted and the channel narrows.  
      In accordance with a further aspect of the invention, the bag has separate fill and exit ports, and the exit port is connected by flexible tubing to an ink cartridge to provide a closed supply system which does not require any venting in the system, such as by a vent hole somewhere in the system, and the totally closed system eliminates any chance of spillage during handling by a user. The separate fill and exit ports advantageously facilitates filling the bag in a manner which minimizes air bubbles in the ink delivery system.  
      In accordance with another aspect of the invention, the flexible supply tubing is coupled with the ink cartridge so as to minimize any interference with respect to manipulating the cartridge into and from its location in a printer and to minimize the application of any strain on the tubing which would potentially affect the fluid flow connection thereof with the cartridge. Preferably, with respect to these attributes, the cartridge has an inlet coupling having a leg parallel to the top wall of the cartridge, and the tubing extends upwardly along an end or side wall of the cartridge and through a tube clamping device mounted on the cartridge or an opening through the cartridge handle for connection with the leg of the inlet coupling. Accordingly, the tubing is closely adjacent to the top and walls of the cartridge and is associated therewith so as to allow full use of the cartridge handle for installing and removing the cartridge relative to a printer while being relieved of strain at the point of connection with the cartridge. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The foregoing advantages 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 preferred embodiments illustrated in the accompanying drawings in which:  
       FIG. 1  is a perspective view of the component parts of an ink delivery system in accordance with the invention;  
       FIG. 2  is a cross-sectional elevation view through the reservoir bag taken along line  2 - 2  in  FIG. 1 ;  
       FIG. 3  is an enlarged sectional elevation view through the fill port of the bag taken along line  3 - 3  in  FIG. 2 ;  
       FIG. 4  is an enlarged sectional elevation view through the exit port of the bag taken along line  4 - 4  in  FIG. 2 ; and,  
       FIG. 5  is a perspective view of the component parts, except for the reservoir bag, of another embodiment of an ink delivery system according to the invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
      Referring now in greater detail to the drawings, wherein the showings are for the purpose of illustrating preferred embodiments of the invention only and not for the purpose of limiting the invention, an ink delivery system  10  in accordance with the present invention includes, primarily, an ink reservoir bag  12 , an ink cartridge  14  and a flexible ink supply tube  16  connecting the cartridge with the reservoir bag as set forth hereinafter. Preferably, as is also set forth in greater detail hereinafter, the system further includes an enclosure for the reservoir bag which, in the embodiment of  FIG. 1 , comprises tray-like bottom and cover components  18  and  20 , respectively. Still further, a check valve  22  is preferably provided in supply tubing  16  for precluding the back flow of ink into the reservoir bag, an ell fitting  24  is provided for routing the supply tubing parallel to the top wall of the cartridge, and strain relieving and clamping arrangements are provided which, respectively, relieve the strain on the supply tubing at the fitting and provide for selectively opening and closing the supply tubing to the flow of ink from the reservoir bag to the ink cartridge. In the embodiment of  FIG. 1 , both of the strain relief and clamping functions are provided by a clamping device  26  mounted on the cartridge.  
      As shown in  FIGS. 1-4 , bag  12  is defined by a pair of sheets flexible plastic material  28  and  30  having corresponding peripheral edges  28   a  and  30   a  which overlie one another and are bonded together, such as by heat sealing, to provide an ink chamber  32  therebetween. Preferably, sheets  28  and  30  are polyvinylchloride sheets having a thickness of 0.015 inch. When filled with ink as depicted in  FIGS. 1-4 , the bag has a length L, a width W, and a height H and, in accordance with one aspect of the invention, these dimensions provide an Aspect Ratio which preferably is greater than 4. The Aspect Ratio, as mentioned hereinabove, is the lesser of the length and width dimensions divided by the height dimension.  
      In accordance with one aspect of the invention, ink reservoir bag  12  has separate inlet and exit ports respectively defined by inlet and exit tubes  34  and  36  which extend between and are bonded to sheets  28  and  30  along the perimeter of the bag as defined by peripheral edges  28   a  and  30   a  of the sheets. Preferably the fill and exit ports extend through the periphery of the bag along one of the narrower dimensions as defined by width W and the tubes are bonded to the sheets such as by a heat seal or through the use of a suitable adhesive. The tubes have inner ends which open into chamber  32  and outer ends which extend a short distance beyond the outermost edges of peripheral edges  28   a  and  30   a  of the sheets. In a preferred embodiment, exit port tube  36  has an inner diameter of 0.17 inch, an outer diameter of 0.25 inch, and a length of 0.75 inch, and fill port tube  34  has an inner diameter of 0.24 inch, an outer diameter of 0.30 inch, and a length of 0.75 inch. Check valve  22  is interposed between tube  36  and tubing  16  and, in this respect, includes an inlet stem  38  received in the outer end of tube  36  and an outlet stem  40  received in supply tubing  16 . Fill port tube  34  provides an injection sight for a lure lock component  42  having a stem  44  received in the outer end of tube  34 . Preferably, supply tubing  16  has an inner diameter of 0.12 inch and is silicone tubing having a durometer hardness of 50. It will be appreciated, however, that PVC or vinyl tubing having durometer values in the range of 65-70 can be used as well as other tubing.  
      In accordance with another aspect of the invention, and as mentioned above, a container comprising bottom and cover components  18  and  20 , respectively, is provided for enclosing reservoir bag  12  to provide protection for the latter, including protection against the application of pressure on the bag during shipping, system installation and cleaning procedures. Moreover, the container facilitates stacking of the containers in a printer and adds aesthetically to the supply system. In the embodiment illustrated, bottom  18  is constructed from a sheet of suitable cardboard which is cut and folded to provide a bottom wall  46 , opposite side walls  48  and opposite end walls  50 , and the side walls and end walls are interconnected at the junctures therebetween by metal corner staples  52 . Similarly, cover  20  is constructed from cardboard material which is cut and folded to provide a top wall  54  opposite side walls  56  and opposite end walls  58 . Again, the side walls and end walls are interconnected at the junctures therebetween by metal corner staples  52 , and it will be appreciated that top wall  54 , side walls  56 , and end walls  58  are dimensioned in length and width for cover  20  to receive bottom  18  therein with the side walls and end walls thereof within and facially engaging the corresponding one of the side walls and end walls of the cover. Preferably, the side walls and end walls of bottom  18  and cover  20  are of a height which provides for the bottom edges of the side walls and end walls of the cover to be generally coplanar with the outer side of bottom wall  46  of the bottom of the container. End walls  50  and  58  at one end of each of the bottom and cover components are each provided with a pair of spaced apart U-shaped slots  60  and  62  opening into the corresponding end wall from the free edge thereof. When the bottom and cover components are assembled with bag  12  therebetween, each of the pairs of slots  60  and  62  cooperatively provide a generally circular opening through which exit port  38  and fill port  34  extend, respectively, such that the check valve and lure lock components are outside the container. It will be appreciated, of course, that other container structures can be used. In this respect, for example, the bottom and top components can be constructed from plastic material, and with such a construction the top could be a flat sheet of plastic overlying and suitably supported on and/or interengaged with the bottom.  
      Ink cartridge  14  has a front wall  64 , a top wall  70 , and a rear wall  72  and, in a well-known manner, the cartridge is provided with a handle  74  at the juncture between top wall  70  and rear wall  72 . As is further well known, the cartridge includes a printhead  76 . Handle  74  facilitates introducing and removing the cartridge relative to a cartridge holder in a printer. As mentioned above, cartridge  14  includes an ell fitting  24  for connecting tubing  16  with the cartridge and a clamping device  26  which, in this embodiment, is operable to open and close tubing  16  to the flow of ink to and from the cartridge and, additionally, provides strain relief for the connection of tubing  16  to fitting  24 . More particularly with regard to these features, fitting  24  includes first and second legs  78  and  80 , respectively, and leg  78  extends downwardly through top wall  70  and is suitably interengaged with the cartridge for the inner end of the leg to open into the ink chamber of the cartridge. Second leg  80  is closely adjacent to top wall  70  and extends parallel thereto and toward handle  74  of the cartridge. The corresponding end of tubing  16  is attached to leg  80 , and the disposition of leg  80  relative to top wall  70  of the cartridge advantageously enables maintaining a low profile for the cartridge and tubing as well as optimizing protection of the tubing. Clamping device  26  includes first and second clamping members  82  and  84 , respectively, and member  82  is suitably mounted on the cartridge against displacement relative thereto. Clamping member  84  is mounted on member  82  for sliding interengagement therewith, and a spring  86  is interposed between the two members and biases member  84  to the position thereof shown in  FIG. 1  relative to member  82 . Tubing  16  extends downwardly between the clamping members and, in the position of the component parts shown in  FIG. 1 , the clamping members interengage the tubing therebetween so as to close the latter to the flow of ink therethrough. When the clamping members are in the position shown in  FIG. 1 , the cartridge is out of the printer and, when the printer is introduced into a cartridge holder in the printer, clamping member  84  engages against a wall of the holder and is displaced rearwardly relative to member  82  whereby, when the cartridge is fully in the printer, the clamping members are disengaged from the tubing so as to allow the flow of ink therethrough. Regardless of whether the clamping members are in the clamping or unclamping positions thereof, the passage of tubing  16  therebetween and thence to leg  80  of fitting  24  relieves strain on the tubing at the point of connection thereof with fitting  24 .  
       FIG. 5  illustrates an alternative to the clamping and strain relief arrangement shown in  FIG. 1 . In this respect, clamping is achieved through the use of a manually operable pinch clamp  88  mounted on tubing  16  and, preferably, within three to four inches of the connection of tubing  16  with fitting  24 . Strain relief for the tubing is provided by extending the tubing upwardly through an opening  90  through handle  74  and generally centrally between the opposite sides thereof and thence parallel across top wall  70  of the cartridge to leg  80  of fitting  24 . As will be appreciated from  FIGS. 1 and 5 , both arrangements advantageously allow full use of the cartridge handle for installation and removal of the cartridge relative to a printer. It will be appreciated in connection with  FIG. 5  that the pinch clamp is in a closed position during shipping, system installation or cleaning procedures when the cartridge is outside a printer, and that the clamp is open during normal printer operations. It will be appreciated that other strain relief arrangements of this character can be devised. In this respect, for example, the tubing can enter an opening in the top of the cartridge handle and exit through an opening in the side of the handle, depending on the routing desired for the tubing.  
      While considerable emphasis has been placed herein on the structures of and structural interrelationships between the component parts of the preferred embodiments of the invention, it will be appreciated that other embodiments can be devised and that many changes can be made in the preferred embodiments without departing from the principals of the invention. In particular in this respect, it is to be understood that a bag formed by folding a sheet of plastic material to provide overlying sheets bonded about the periphery thereof is intended to correspond to a bag comprising two sheets of plastic material having peripheral edges bonded together as shown and described herein. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation and that it is intended to include other embodiments and all modifications of the preferred embodiments insofar as they come within the scope of the appended claims or the equivalents thereof.