Abstract:
A method of forming a conduit providing fluid communication between respective reservoirs of an ink tank, the method comprising the steps of: (a) forming a first orifice extending through a first external wall portion of an ink tank defining part of a first ink reservoir of the ink tank; (b) forming a second orifice extending through a second external wall portion of the ink tank defining part of a second ink reservoir of the ink tank; and (c) attaching a substrate over the first and second external wall portions at least about a first continuous seal line surrounding both the first and second orifices to define an external conduit communicatively connecting the first ink reservoir with the second ink reservoir.

Description:
FIELD OF THE INVENTION 
   The present invention concerns reservoirs for storing liquid contents and, more specifically, to reservoirs utilized to store liquid ink for inkjet printer applications. 
   BACKGROUND AND SUMMARY 
   The present invention concerns containers utilized to house liquids and, more specifically, to containers utilized to house liquid ink for inkjet printer applications. Ink containers may be integral with a printhead or communicatively connected thereto. In applications where replacement ink containers are communicatively connected to a permanent printhead, it is desirable that the container be able to supply ink in a predictable manner. Exemplary replacement ink containers may includes one or more chambers filled or partially occupied by liquid ink. To impart a predictable flow of ink from the container to the printhead, the container may house one or more backpressure mediums. Backpressure mediums are mediums that include pores through which liquids can flow, but that provide a resistance to flow resulting from capillary action. Typical backpressure mediums include felts, foams, and other fibrous mediums having pores sizes imparting predictable resistance to fluid flow from the resulting capillarity. 
   In order to increase the utilization of ink within a container, it is usually preferred that the backpressure medium occupy as little space as possible to satisfy the breathing requirements of the container. At the same time, less backpressure medium results in less control over the flow of ink from the container. In other words, a balance is generally arrived at that involves providing one chamber of the container having a backpressure medium (backpressure chamber) that is in communication with another chamber of the container housing only liquid ink or a combination of liquid ink and trapped gases (free ink chamber). 
   Conventional ink containers provide for transfer of liquid ink between free ink chambers and backpressure chambers using one or more openings through internal walls of the container that would otherwise separate the chambers. Typically, one or more internal walls step as a partition, but for an opening through the lower level of the wall to allow ink to travel from the free ink chamber and into the backpressure chamber only when the level of ink within the backpressure chamber drops below a predetermined point. This predetermined point typically coincides with the level of the opening between the chambers so that air bubbles from the backpressure chamber can flow into the free ink chamber to displace liquid ink, thereby driving liquid ink into the backpressure chamber until the level of ink within the backpressure chamber rises and cuts off the opening, discontinuing gaseous transfer into the free ink chamber and liquid ink transfer into the backpressure chamber. 
   Some embodiments of the instant invention provide an alternative to the internal wall openings and provides conduits that extend outside of the conventional ink container by utilizing a substrate mounted to the exteriors of the chambers that allow communication between the free ink chamber and the backpressure chamber, with or without requiring molding of openings within internal walls. Some embodiments also provide manufacturing alternatives that allow the formation of openings within the internal wall separating the chambers without requiring tooling to be substantially constrained by the dimensions of the ink container. 
   Some embodiments of the present invention to provide a method of forming a conduit providing fluid communication between respective reservoirs of an ink tank, that include the steps of: (a) forming a first orifice extending through a first external wall portion of an ink tank defining part of a first ink reservoir of the ink tank; (b) forming a second orifice extending through a second external wall portion of the ink tank defining part of a second ink reservoir of the ink tank; and (c) attaching a substrate over the first and second external wall portions at least about a first continuous seal line surrounding both the first and second orifices to define an external conduit communicatively connecting the first ink reservoir with the second ink reservoir. 
   In an embodiment, the method further includes the step of providing at least one depression in the first and second external wall portions extending between the first and second conduits. In another embodiment, the method further includes the steps of (i) forming a third orifice extending through a third external wall portion of the ink tank defining part of the first ink reservoir; (ii) forming a fourth orifice extending through a fourth external wall portion of the ink tank defining part of the second ink reservoir; and (iii) attaching a second substrate over the third and fourth external wall portions at least about a second continuous seal line surrounding both the third and fourth orifices to define a second external conduit communicatively connecting the first ink reservoir with the second ink reservoir. In a further embodiment, the first orifice is adjacent to a first felt member occupying at least a portion of an internal area of the first ink reservoir, and the second orifice is in direct communication with free ink occupying at least a portion of an internal area of the second ink reservoir. 
   In yet another embodiment, the first and second substrates include a single substrate and the single substrate comprises the first and second seal lines. In still another more detailed embodiment, the first orifice and the second orifice of the first ink reservoir are adjacent to a first felt member occupying at least a portion of an internal area of the first ink reservoir, the first orifice and the second orifice of the second ink reservoir are in direct communication with free ink occupying at least a portion of an internal area of the second ink reservoir, and the combination of the first conduit and the second conduit provides the exclusive manner for fluids to traverse between the first reservoir and the second reservoir. In a further embodiment, the substrate comprises a polymer film, and the first portion of the film is laminated to an exterior wall of the first ink reservoir and to an exterior wall of the second ink reservoir. In still a further detailed embodiment, the step of laminating the first portion of the substrate to the first ink reservoir and to the second ink reservoir includes at least one of heat staking, laser welding, ultrasonic welding, vibrational welding, and adhesive mounting a film to an exterior wall of the first ink reservoir and to an exterior wall of the second ink reservoir. 
   Some embodiments described herein include a method of forming a conduit providing fluid communication between respective reservoirs of an ink tank, the method comprising the steps of: (a) forming a first orifice through a wall of an ink tank and into communication with a first reservoir and a second reservoir of the ink tank; and (b) sealing a substrate to the ink tank to overlap the first orifice and form a first by-pass conduit communicatively connecting the first reservoir and the second reservoir. 
   In a more detailed embodiment, the method further includes the steps of: (i) forming a second orifice through the wall of the ink tank and into communication with the first reservoir and the second reservoir of the ink tank; and (ii) sealing the substrate to the ink tank to overlap the second orifice and form a second by-pass conduit communicatively connecting the first reservoir and the second reservoir. In yet another more detailed embodiment, the first reservoir comprises a free ink reservoir, and the second reservoir comprises a backpressure reservoir that is occupied by a backpressure media. In a further detailed embodiment, the combination of the first conduit and the second conduit provides the exclusive manner for fluids to traverse between the first reservoir and the second reservoirs and the substrate comprises a polymer film. 
   Some embodiments of the present invention provide an ink tank comprising: (a) a first reservoir for housing a liquid ink, the first reservoir including a first orifice through a wall at least partially defining an interior region of the first reservoir; (b) a second ink reservoir for housing a liquid ink, the second ink reservoir including a first orifice through a wall at least partially defining an interior region of the second reservoir; and (c) a first conduit overlapping the first orifice of the first ink reservoir and the first orifice of the second ink reservoir allowing fluid communication between the first reservoir and the second reservoir, the first conduit defined at least in part by a film mounted to the wall of the first ink reservoir and to the wall of the second ink reservoir. 
   In a more detailed embodiment, the first reservoir comprises a backpressure chamber housing at least one backpressure medium through which liquid ink traverses prior to exiting through an ink outlet orifice of the backpressure chamber, and the second reservoir comprises a free ink chamber housing liquid ink prior to entering the backpressure chamber. In yet another more detailed embodiment, the free ink chamber and the backpressure chamber share a common wall, and the common wall includes an opening therethrough providing a second conduit between the free ink chamber and the backpressure chamber. In a further detailed embodiment, at least one of the wall of the first reservoir and the wall of the second reservoir includes a furrow extending lengthwise in parallel with a line of travel between the first orifices. In still a further detailed embodiment, the ink tank further comprises: (i) a second orifice through the wall at least partially defining the interior region of the first reservoir; (ii) a second orifice through the wall at least partially defining the interior region of the second reservoir; and (iii) a second conduit overlapping the second orifice of the first ink reservoir and the second orifice of the second ink reservoir to allow fluid communication between the second orifices, the second conduit defined at least in part by a film mounted to the wall of the first ink reservoir and to the wall of the second ink reservoir. 
   Some embodiments of the present invention provide an ink tank comprising: (a) a first vessel defining a first ink reservoir; (b) a second vessel defining a second ink reservoir; and (c) a first by-pass conduit communicatively connecting the first vessel to the second vessel by way of a first orifice that concurrently exposes the first vessel and the second vessel, the first by-pass conduit comprising a first substrate overlapping the first orifice and enclosing one side of the first orifice to allow sealed fluid communication between the first vessel and the second vessel. 
   In a more detailed embodiment, the first reservoir comprises a free ink reservoir for supplying liquid ink to the second reservoir, and the second reservoir comprises a backpressure reservoir housing at least one backpressure medium through which liquid ink traverses prior to exiting through an ink outlet orifice of the second vessel. In yet another more detailed embodiment, the first vessel and the second vessel share a common wall that includes an opening therethrough directly linking the first reservoir to the second reservoir. In a further detailed embodiment, the ink tank further comprises a second by-pass conduit communicatively connecting the first vessel to the second vessel by way of a second orifice that concurrently exposes the first vessel and the second vessel. In still a further detailed embodiment, the second by-pass conduit comprises a separate substrate overlapping the second orifice and enclosing one side of the second orifice to allow sealed fluid communication between the first vessel and the second vessel. In a more detailed embodiment, the ink tank further comprises a second by-pass conduit communicatively connecting the first vessel to the second vessel by way of corresponding orifices that expose the first vessel and the second vessel, the second by-pass conduit comprising a second substrate overlapping the corresponding orifices and enclosing a side of the corresponding orifices to allow sealed fluid communication between the first vessel and the second vessel. In a more detailed embodiment, the first substrate and the second substrate comprise a polymer film. 
   Some embodiments of the present invention provide a method of facilitating fluid communication between chambers of an ink tank, the method comprising the steps of: (a) forming a hole through an exterior wall bounding a first chamber of an ink tank; (b) forming a hole through an exterior wall bounding a second chamber of an ink tank; and (c) sealing a film to the exterior wall of the first chamber and to the exterior wall of the second chamber to encompass the hole of the first chamber and the hole of the second chamber to create an external sealed conduit providing fluid communication between the first chamber and the second chamber. 
   Some embodiments of the present invention provide a method of establishing countercurrent fluid transfer between areas of an ink tank, the method comprising the step of sealing a film to an exterior surface of an ink tank to define a first sealed exterior passage between at least two compartments of the ink tank, the seal between the film and the exterior surface of the ink tank outlining at least a first opening through the ink tank. 
   In a more detailed embodiment, the method further comprises the step of sealing a second film to the exterior surface of the ink tank to define a second sealed exterior passage between at least two compartments of the ink tank, the seal between the film and the exterior surface of the ink tank outlining at least a second opening through the ink tank. In yet another more detailed embodiment, the step of sealing the second film to the exterior surface of the ink tank seals the second sealed exterior passage to the exclusion of the first sealed exterior passage. In a further detailed embodiment, the ink tank includes an interior passage through an interior wall of the ink tank providing fluid communication between the first chamber and the second chamber of the ink tank, where the interior passage allows fluid to flow in a first direction from the first chamber to the second chamber, and the first sealed exterior passage allows fluid to flow in a second direction, opposite that of the first direction. 
   Some embodiments of the present invention provide a method of forming an ink tank, the method comprising: (a) molding at least two ink chambers of an ink tank, each ink chamber is defined by vertical walls that intersect a horizontal wall, where the at least two chambers share a common wall dividing the chambers from one another; (b) forming a first orifice and a second orifice through the horizontal floor, where the second orifice is vertically overlapped by the common wall; (c) mounting a lid to the vertical walls opposite the horizontal wall; and (d) mounting a film over the first orifice and the second orifice to inhibit fluid from egressing through the orifices. 
   In a more detailed embodiment, the common wall includes an opening therethrough providing fluid communication between the at least two chambers, and the step of forming the second orifice through the horizontal wall includes removing material from the horizontal wall to create the second orifice and further includes removing material from the common wall directly above the second orifice to form the opening through the common wall. In a further detailed embodiment, further comprising the step of: (i) forming a first orifice through a vertical wall defining the first chamber; (ii) forming a first orifice through a vertical wall defining the second chamber; and (iii) mounting a film to the vertical wall of the first chamber and to the vertical wall of the second chamber to encompass the first orifices and provide a sealed conduit between the first chamber and the second chamber. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is profile, cross-sectional view of a first exemplary ink tank in accordance with the present invention; 
       FIG. 2  is a profile view of a second exemplary ink tank in accordance with the present invention; 
       FIG. 3  is a frontal view of the second exemplary ink tank of  FIG. 2 ; 
       FIG. 4  is a profile view of a third exemplary ink tank in accordance with the present invention; 
       FIG. 5  is a frontal view of the third exemplary ink tank of  FIG. 4 ; 
       FIG. 6  is a profile view of a fourth exemplary ink tank in accordance with the present invention; 
       FIG. 7  is a profile view of a fourth alternate exemplary ink tank in accordance with the present invention; 
       FIG. 8  is a profile view of a fifth exemplary ink tank in accordance with the present invention; and 
       FIG. 9  is a profile view of a sixth exemplary ink tank in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
   The exemplary embodiments of the present invention are described and illustrated below to encompass reservoirs for storing fluid contents. Of course, it will be apparent to those of ordinary skill in the art that the preferred embodiments discussed below are exemplary in nature and may be reconfigured without departing from the scope and spirit of the present invention. However, for clarity and precision, the exemplary embodiments as discussed below may include optional steps, methods, and features that one of ordinary skill should recognize as not being a requisite to fall within the scope of the present invention. 
   Referencing  FIG. 1 , a first exemplary ink tank  10  includes a backpressure chamber  12  and a free ink chamber  14  partially separated from one another by an internal wall  16 . An orifice  18  through the internal wall  16  provides direct communication between the chambers  12 ,  14 . Right and left side walls (not shown) are connected to one another by way of a front wall  20 , a floor  22 , a lid  24 , and the internal wall  16 , which collectively generally define the backpressure chamber  12 . An outlet opening  26  is included in the floor  22  that provides access to the interior of the backpressure chamber  12 . The opening  26  is sealed using a film  28  (or gasket (not shown)) to be removed by a consumer prior to use of the ink tank  10 . The opening  26 , subsequent to film  28  removal, is adapted to accommodate at least partial throughput of a snout of an ink receptacle (not shown) to facilitate transfer of liquid ink from the backpressure chamber to a plurality of nozzles of printhead (not shown). 
   Two backpressure mediums  30 ,  32  occupy the interior of the backpressure chamber  12 . The first backpressure medium  30  occupies a lower portion, while the second backpressure medium  32  occupies the top portion. Each backpressure medium  30 ,  32  includes numerous pores that allow liquid ink and gases to travel through the medium, however, the liquid flow is retarded from gravitationally egressing through the medium by capillary action. In this exemplary embodiment, the first backpressure medium  30  is typically a higher backpressure and higher density felt, foam, or fiber while the second backpressure medium  32  is a lower backpressure and lower density felt, foam, or fiber. The pore size of the second backpressure medium  32  retards the flow of liquid ink to a lesser extent than that of the first backpressure medium  30 . 
   A vent  34  within the lid  24  is in communication with the second backpressure medium  32  and the external environment. In this exemplary embodiment, the vent  34  includes a serpentine trench (not shown) in communication with the vent opening through the lid  24  that cooperates with an adhesive label  36  to provide a serpentine conduit (not shown), with a portion of this adhesive label  36  being removed prior to installation in order to expose the serpentine conduit to the external environment. Thus, as liquid ink flows through the second backpressure medium  32  to replace the ink withdrawn from the first backpressure medium  30  via the opening  26 , gases flow into the backpressure chamber  12  through the vent  34  to replace the volume within the backpressure medium  32  no longer occupied by liquid ink. It is also within the scope of the invention to utilize a vent seal or vent tape (not shown), separate from the adhesive label  36 , that a user removes prior to installation of the tank  10  that overlies the exposed end of the serpentine conduit. 
   The free ink chamber  14  is also defined by right and left side walls (not shown), the floor  22 , the lid  24 , and a rear wall  38 . In this exemplary embodiment, the free ink chamber  14  is adapted to be occupied by liquid ink, with no backpressure medium. The floor  22  includes an orifice  40  that is sealed using a polymer film  42 . The application of the film  42  to the underside of the floor  22  does not hinder the functionality of the orifice  18  through the internal wall  16 . Therefore, liquid ink enters the backpressure chamber  12  when the level of liquid ink within the backpressure chamber  12  drops sufficiently to allow gas from the backpressure chamber  12  to enter the free ink chamber  14 . As will be discussed in more detail hereafter, the orifices  18 ,  40  may be formed using a plurality of different techniques. 
   Fabrication of the exemplary ink tank  10  includes injection molding the floor  22 , side walls, front and rear walls  20 ,  38 , and interior wall  16  as a single piece structure. When molded in this exemplary process, the interior wall  16  completely separates the backpressure chamber  12  from the free ink chamber  14 . After the single piece structure is molded, it is removed from the mold and processed by a cutting tool (not shown) that creates one opening  40  or both of the openings  26 ,  40  within the floor, given that one of the openings  26  may be formed during the molding process. After forming the opening  40  through the floor  22 , the cutting tool continues vertically upward to remove a portion of the internal wall  16 , thereby forming the orifice  18 . 
   Alternatively, the exemplary ink tank  10  may be fabricated by injection molding the floor  22 , side walls, front and rear walls  20 ,  38 , and interior wall  16  as a single piece structure, along with molding both of the openings  26 ,  40  within the floor and the orifice  18  through the interior wall  16 . Creating the orifice  18  in this manner does not require utilization of molding slides that might otherwise complicate the molding process. 
   Regardless of the fabrication approach utilized, the first polymer film  28  and the second polymer film  42  are laid over the openings  28 ,  40  in the floor  22  to create a fluidic seal across the floor. An adhesive process is performed to mount the first film  28  to the outlet opening  26 , whereas a heat staking operation is performed to attach the second film  42  to the second opening  40 , thereby inhibiting fluid communication through the outlet orifice  26  and the opening  40 . It is to be understood that the first film  28  is mounted to enable eventual removal, whereas the second film is mounted to inhibit removal. Thereafter, each backpressure medium  30 ,  32  is inserted into the backpressure chamber  12 , followed by mounting the lid  24  to complete the formation of the chambers  12 ,  14 . 
   It is to be understood that ink may be added at various stages during the exemplary fabrication process such as, without limitation, after the introduction of the backpressure media  30 ,  32 , or after mounting the lid  24 . Moreover, the ink may be introduced after mounting of the lid  24  by introducing ink through a fill port (not shown) formed through the lid. Those of ordinary skill are familiar with conventional fill ports and the devices utilized to plug the fill ports, such as fill balls, subsequent to an ink fill operation. Therefore, the exemplary fabrication sequence is amendable to many obvious variations incorporating the aforementioned features and process steps. 
   Referencing  FIGS. 2 and 3 , a second exemplary ink tank  110  includes a backpressure chamber  112  and a free ink chamber  114  separated from one another by an internal wall  116 . An external conduit assembly  118  connects the chambers  112 ,  114  to one another for the transfer of gases into the free ink chamber  114  and the transfer of ink into the backpressure chamber  112 . The external conduit assembly  118  is bounded in part by an exterior wall  124  of the tank  110 , which may optionally have grooves, pathways or other such depressions  125  molded or otherwise formed therein, as well as by a polymer film  126  sealed substantially about its periphery to the exterior wall  124  that encompasses two inlet/outlet orifices  128 ,  130  extending through the exterior wall  124  and further encompassing the depressions  125  extending between the inlet/outlet orifices  128 ,  130 . The first inlet/outlet orifice  128  provides access to the interior of the backpressure chamber  112 , while the second inlet/outlet orifice  130  provides access to the interior of the free ink chamber  114 . Because the continuous seal  127  between the polymer film  126  and the exterior wall  124  surrounds both inlet/outlet orifices  128 ,  130 , fluid communication is provided between the inlet/outlet orifices  128 ,  130 . The optional depressions  125  may also facilitate or improve fluid communication between the inlet/outlet orifices  128 ,  130  after the film  126  is sealed over the exterior wall  124 . Such depressions  125  could possibly allow the film  126  to be sealed across the exterior wall&#39;s flat surface, thereby allowing for lesser precision in the sealing operation; or the depressions could be used in addition to the surrounding seal  127 . 
   The backpressure chamber  112  acts as a holding area for ink prior to the ink egressing through an outlet orifice  132 . Four vertical walls  116 ,  124 ,  140 ,  142 , a floor  136 , and a top lid  138  define the interior region of the backpressure chamber  112 . The interior region is majority occupied by one or more backpressure mediums (not shown) that are in communication with a vent  144  formed through the top lid  138 . A second polymer film  146  is mounted to the floor  136  and circumscribes the outlet orifice  132  to inhibit ink from egressing through the outlet orifice. Finally, a label  148  is adhesively mounted over the lid  138  and cooperates with the vent  144  to provide a serpentine conduit (not shown) between backpressure chamber  112  and an external environment to inhibit ink from egressing from the backpressure chamber  112 . As with the first exemplary embodiment, a portion of the label  148  may be removed to expose one end of the serpentine conduit, or a separate a vent seal or vent tape (not shown) may be removed to expose one end of the serpentine conduit. 
   The free ink chamber  114  is adapted to house liquid ink prior to the ink being introduced into the backpressure chamber  112 . In this exemplary embodiment, the interior of the free ink chamber  112  is defined by four vertical walls  116 ,  124 ,  142 ,  150 , the floor  136 , and the top lid  138 . Ink travels from the free ink chamber  114  and through the conduit assembly  118  into the backpressure chamber  112  when the level of ink within the backpressure chamber  112  drops sufficiently to allow gas from the backpressure chamber  112  to enter the conduit assembly  118  and travel into the free ink chamber  114 . 
   Fabrication of the second exemplary ink tank  110  includes injection molding the floor  136 , vertical walls  116 ,  124 ,  140 ,  142 ,  150  as a single piece structure. Each of the orifices  128 ,  130 ,  132  through, and depressions in, the exterior wall  124  are molded or are later cut or otherwise formed in the wall  124 . Thereafter, the first polymer film  126  is laid over the orifices  128 ,  130  (and the optional depressions  125  extending therebetween), while the second polymer film  146  is laid over the outlet orifice  132 . In the exemplary embodiment, a heat staking operation is performed to attach the film  126  to the exterior wall  124  along a seal  127  circumscribing collectively the orifices  128 ,  130  to form the conduit  118 . The other film  146  is attached to the underside of the floor  136  using an adhesive and the film circumscribes the outlet orifice  132 , thereby inhibiting fluid communication through the outlet orifice  132 . A backpressure medium (not shown) is inserted into the backpressure chamber  112 , followed by mounting the lid  138  to the exposed tops of the walls  116 ,  124 ,  140 ,  142 ,  150  to complete the formation of the chambers  112 ,  114 . Ink is also introduced in to chambers  112 ,  114 , followed by mounting the label  148  to the lid  138 . 
   Referencing  FIGS. 4 and 5 , a third exemplary ink tank  210  includes a plastic unitary body  214  and a top lid  216 . The unitary body  214  includes side walls  218 ,  219 , a front wall  220 , an internal wall  222 , a rear wall  224 , and a floor  226 . An orifice  228  through the internal wall  222  allows communication between a free ink chamber  230  and a backpressure chamber  232 . The top lid  216  is mounted to the exposed end of the unitary body  214  and includes a vent  234  allowing communication between an external environment and the interior of the backpressure chamber  232 . 
   An external conduit assembly  236  also provides communication between the respective chambers  230 ,  232 . The conduit assembly  236  is defined by the cooperation of a film  238  mounted substantially about its periphery to the exterior of the side wall  218 , where the seal  239  between the wall  218  and the film  238  surrounds two inlet/outlet orifices  240 ,  242  formed through the side wall  218 . One of the inlet/outlet orifices  240  leads into the interior of the backpressure chamber  232 , while the other inlet/outlet orifice  242  leads into the interior of the free ink chamber  230 . Depressions  243  within the side wall  218  run between the orifices  240 ,  242  and are operative to provide fluid communication between the inlet/outlet orifices  240 ,  242 . 
   Even when an outlet orifice  244  of the backpressure chamber  232  is sealed by a second film  246 , and the vent  234  is sealed by a label  248  or other sealing material, the ink and gases may be exchanged between the chambers  230 ,  232  via the external conduit assembly  236  to accommodate for pressure changes exerted upon the fluids within the chambers  230 ,  232 . In a preferred installation and subsequent operation, a portion of the label  248  and the entire film  246  are removed, and ink flows from the backpressure chamber  232  through the orifice  244  and gases flow into the backpressure chamber  232  by way of the vent  234  in order to replace the volume previously occupied by liquid ink. Preferably, the backpressure chamber  232  houses a saturated medium, while the free ink chamber houses ink. Eventually, the level of ink within the backpressure chamber  232  drops and allows gas within the backpressure chamber  232  to be exposed to the inlet/outlet orifice  240 . At this point, a transfer cycle is created similar to that between the vent  234  and outlet orifice  244 , where gas from the backpressure chamber  232  enters the free ink chamber  230  by way of the conduit assembly  236 , and ink travels from the free ink chamber  230  into the backpressure chamber  232  in an amount roughly equal to the volume of gas entering the free ink chamber  230  from the backpressure chamber  232 . In this manner, gas and ink can freely travel into their respective chambers without the other fluid hindering the progress as the gas can travel via the conduit  236  and the liquid ink can travel via the opening  228 . This cycle of gas displacing the liquid ink in the free ink chamber  230  continues until the level of ink within the backpressure chamber  232  is below that of the openings  228 . Gas may travel into the free ink chamber using a combination of the opening  228  and the conduit assembly  236 . Continued ejection of the ink from the backpressure chamber  232  via the outlet orifice  244  continues until both of the chambers  230 ,  232  are essentially empty of ink. 
   Fabrication of this third exemplary ink tank  210  includes injection molding the floor  226 , vertical walls  218 ,  219 ,  220 ,  222 ,  224 , as a single piece structure in which each of the orifices  228 ,  240 ,  242 ,  244  has already been formed. Thereafter, the first polymer film  238  is heat staked to form an outline seal surrounding the inlet/outlet orifices  240 ,  242 , while the second polymer film  246  is adhesively mounted over the outlet orifice  244 . 
   An applicable backpressure medium (not shown) is inserted into the backpressure chamber  232 , followed by mounting the lid  216  to the exposed walls of the single piece structure  214 , thereby completing the formation of the chambers  230 ,  232 . Ink is then introduced into the chambers by way of an ink fill port (not shown), followed by mounting the label  248  to the lid  216  to seal the vent  234  and render the tank  210  ready for shipment. 
   Referencing  FIG. 6 , a fourth exemplary ink tank  310  includes essentially the same structure as the second exemplary ink tank  110 , but also includes two additional inlet/outlet orifices  312 ,  314  covered by an additional polymer film  316  which is heat staked to the exterior wall  124  forming a seal line  317  surrounding the inlet/outlet orifices  312 ,  314 . The orifices  312 ,  314 , the film  316 , and the exterior wall  124  of the tank  310  cooperate to define a second conduit  318  to provide two conduits  118 ,  318  for communication between the free ink chamber  114  and the backpressure chamber  112 . Each conduit  118 ,  318  includes depressions  125 ,  325  directing fluids (i.e., ink, gas, etc.) between the orifices  128 ,  130 ,  312 ,  314 . In this manner, as the level of ink drops within the backpressure chamber  112  below the inlet/output orifice  312 , gases from the backpressure chamber  112  travel through the second conduit  318  in an uninterrupted path, thereby displacing ink with the free ink chamber  114  traveling into the backpressure chamber via the first conduit  118 . In this way, ink and gases may flow through the respective conduits  118 ,  318  in a countercurrent and uninterrupted manner. 
   Fabrication of the fourth exemplary ink tank  310  is consistent with those fabrication steps discussed above for the second exemplary ink tank  110 , in addition to the formation of the orifices  312 ,  314 . The orifices  312 ,  314  are molded into the exterior wall  124  of the floor  136  and walls  116 ,  124 ,  140 ,  150  of the tank  310 . Application of the film  316  to the exterior wall  124  is consistent with the processes discussed in the second exemplary embodiment for attaching the first film  126  to the exterior wall  124  to maintain a fluidic seal between the film and wall. In this regard, separate pieces of film may be used to fabricate the first and second conduits  118 ,  318 , or a single piece of film  350  may be utilized to form the separate conduits  118 ,  318  to produce a fourth alternate exemplary ink tank  310 ′ (see  FIG. 7 ). As shown in  FIG. 7 , the single piece film  350  is sealed to the exterior wall about a seal line  351  that surrounds orifices  312  and  314 , and a second seal line  353  that separately surrounds orifices  128  and  130 , thus respectively providing conduits  318 ′ and  118 ′. Those of ordinary skill will readily understand how these fourth exemplary embodiments operate and how these fourth exemplary embodiments may be fabricated following the teachings recited above for the alternate exemplary embodiments of the instant invention. 
   Referencing  FIG. 8 , a fifth exemplary ink tank  410  includes essentially the same structure as the fourth alternate exemplary ink tank  310 ′, but includes a single seal line  445  surrounding the orifices  128 ,  130 ,  312 ,  314 . A bridge  444  is formed within the seal line  445  that allows direct communication between the conduits  118 ′,  318 ′. In this manner, air bubbles caught within the first conduit  118 ′ can travel through the bridge  444  and into the second conduit  318 ′. 
   Fabrication of the fifth exemplary ink tank  410  is consistent with those fabrication steps discussed above for the second exemplary ink tank  110  and the fourth alternate exemplary ink tank  310 ′. Instead of sealing the single film  350  to the exterior wall  124  to define separate conduits  118 ′,  318 ′, the heat seal line  445  surrounds the four orifices  128 ,  130 ,  312 ,  314  and preserves the conduits, while allowing direct communication between the conduits by way of the bridge  444 . 
   Referencing  FIG. 9 , a sixth exemplary ink tank  500  includes a single orifice  502  that bridges the free ink chamber  514  and backpressure chamber  512 . A film  526  is mounted over the orifice  502  and to an external wall  524  of the tank  500  to create a conduit  518 , defined within a seal line  517 , that effectively bridges the chambers  512 ,  514 . Exemplary procedures for mounting the film  526  to the external wall  524  include, without limitation, heat staking and laser welding. The exemplary single orifice  502  may be used in place of the multiple orifices discussed in the first through fifth exemplary embodiments that cooperate to provide entry and exit openings for any of the exemplary conduits discussed herein. 
   In accordance with the foregoing exemplary embodiments, the films utilized to create the conduits between the free ink chamber and the backpressure chamber include, without limitation, polypropylene films, polyethylene films, copolymer films, metallic films, and composite films (such as polymer films interposing metallic films). In addition, the exemplary films may be mounted to the ink tanks using the exemplary heat staking process, as well as other sealing and bonding processes such as, without limitation, laser welding, ultrasonic welding, vibrational welding, and adhesive. Moreover, the term “film” as used herein is not restricted to the literal meaning. By way of example, and not limitation, the term “film” as used herein also encompasses solid plate material and solid preformed bubble castings or moldings that may be mounted to the exemplary tanks to create the exemplary conduits between chambers. 
   Following from the above description and invention summaries, it should be apparent to those of ordinary skill in the art that, while the methods and apparatuses herein described constitute exemplary embodiments of the present invention, the invention contained herein is not limited to this precise embodiment and that changes may be made to such embodiments without departing from the scope of the invention as defined by the claims. Additionally, it is to be understood that the invention is defined by the claims and it is not intended that any limitations or elements describing the exemplary embodiments set forth herein are to be incorporated into the interpretation of any claim element unless such limitation or element is explicitly stated. Likewise, it is to be understood that it is not necessary to meet any or all of the identified advantages or objects of the invention disclosed herein in order to fall within the scope of any claims, since the invention is defined by the claims and since inherent and/or unforeseen advantages of the present invention may exist even though they may not have been explicitly discussed herein.