Abstract:
A printhead comprising a first ink reservoir in fluid communication with an outlet nozzle and downstream from a first ink filter, and a pump assembly in fluid communication with the first ink reservoir and operative to withdraw gas from the first ink reservoir and subsequently inhibit fluid communication between the withdrawn gas and the first ink reservoir. The present invention also includes method of removing gas in fluid communication with an ink reservoir, the method comprising purging gas from a gas accumulation area of an ink reservoir, where purging act includes manipulating a valve assembly downstream from an ink filter, the valve assembly operative to separate the gas accumulation area of the ink reservoir from an external environment, the valve assembly operative to facilitate unidirectional volumetric flow of the gas between the gas accumulation area and the external environment.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is directed to drop-on-demand printing, and more specifically to inkjet printing. The invention includes devices and methods for purging gases becoming entrapped within an ink concourse between an ink supply source and an ejection point at the nozzle tip.  
         [0003]     2. Background of the Invention  
         [0004]     One of the major problems with on-carrier tank systems (“chiclet systems”) concerns the accumulation of air within the ink filter tower. If an ink reservoir is run too low, or left out of the printer for an extended period of time, air may accumulate within the filter tower and block ink from reaching the nozzles; i.e., starving the chip. These conditions will result in premature printhead failure. Several causes are known for the accumulation of air within the ink concourse and include, without limitation, air permeation through the ink supply conduits, air forced into the ink supply conduits resulting from the exchange of ink tanks, as well as dissolved air within the ink that comes out of solution. Therefore, there is a need in the art to develop devices and techniques for obviating air accumulation downstream from an ink filter.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is directed to devices and methods that reduce the likelihood of premature printhead failure caused by starvation of the printhead attributable to gaseous blockages. An exemplary embodiment of the present invention may include an ink reservoir fabricated with special geometric features that provide for gaseous accumulation and separation of the accumulated gases from the liquid ink. Another exemplary embodiment of the present invention may also make use of pumps and valve assemblies that withdraw gases from within one or more ink reservoirs and expel the withdrawn gas to an environment external to the ink reservoirs. A further detailed exemplary embodiment may include refillable ink reservoirs having one or more couplings adapted to interface with removable ink tanks, where the direction of insertion is at least partially horizontal.  
         [0006]     In accordance with an embodiment of the present invention a printhead is provided that includes: (a) a first ink reservoir in fluid communication with an outlet nozzle and downstream from a first ink filter; and (b) a pump assembly in fluid communication with the first ink reservoir and operative to withdraw gas from the first ink reservoir and subsequently inhibit fluid communication between the withdrawn gas and the first ink reservoir.  
         [0007]     In an embodiment, the pump assembly includes a one-way valve assembly in concurrent fluid communication with an interior of the first ink reservoir and an external environment, and the one-way valve assembly includes a first valve and a second valve. In yet another more detailed embodiment, a pump of the pump assembly fluidicly interposes the first valve and the second valve. In a further detailed embodiment, the first valve is operative to isolate the second valve from the interior of the first ink reservoir. In still a further detailed embodiment, the one-way valve assembly includes a first valve that includes a first valve seat adapted to receive a first valve body, where the first valve body is biased against the first valve seat, and a second valve that includes a second valve seat adapted to receive a second valve body, where the second valve body is biased against the second valve seat. In a more detailed embodiment, the first valve seat includes a first circular opening, the first valve body includes a first spherical body adapted to be received within the first circular opening, the second valve seat includes a second circular opening, and the second valve body includes a second spherical body adapted to be received within the second circular opening.  
         [0008]     In another embodiment, the pump assembly includes a pump operative to overcome the bias of the first valve body by generating a first pressure differential between an upstream side and a downstream side of the first valve, thereby providing fluid communication between the upstream side and the downstream side of the first valve, the pump is operative to overcome the bias of the second valve body by generating a second pressure differential between an upstream side and a downstream side of the second valve, thereby providing fluid communication between the upstream side and the downstream side of the second valve, and the downstream side of the first valve is in fluid communication with the upstream side of the second valve. In still another more detailed embodiment, the pump includes a diaphragm deformable to generate the first pressure differential and the second pressure differential, and the diaphragm is manually deformable. In a further detailed embodiment, the printhead further comprises a second ink reservoir in fluid communication with a second outlet nozzle and downstream from a second ink filter and a third ink reservoir in fluid communication with a third outlet nozzle and downstream from a third ink filter, where the second ink reservoir and the third ink reservoir are in fluid communication with the pump assembly operative to withdraw gas from the second ink reservoir and the third ink reservoir and subsequently inhibit fluid communication between the withdrawn gas and the second ink reservoir and the third ink reservoir.  
         [0009]     In another embodiment, the pump assembly includes a one-way valve assembly in concurrent fluid communication with an interior of the first ink reservoir, an interior of the second ink reservoir, an interior of the third ink reservoir, and an external environment, and the one-way valve assembly includes a first valve, a second valve, a third valve, and a fourth valve. In still another more detailed embodiment, the pump assembly includes a pump that fluidicly interposes the first valve and the fourth valve, fluidicly interposes the second valve and the fourth valve, and fluidicly interposes the third valve and the fourth valve. In a further detailed embodiment, the first valve is operative to isolate the fourth valve from the interior of the first ink reservoir, the second valve is operative to isolate the fourth valve from the interior of the second ink reservoir, and the third valve is operative to isolate the fourth valve from the interior of the third ink reservoir. In a more detailed embodiment, the first valve includes a first valve seat adapted to receive a first valve body, where the first valve body is biased against the first valve seat, the second valve includes a second valve seat adapted to receive a second valve body, where the second valve body is biased against the second valve seat, the third valve includes a third valve seat adapted to receive a third valve body, where the third valve body is biased against the third valve seat, and the fourth valve includes a fourth valve seat adapted to receive a fourth valve body, where the fourth valve body is biased against the fourth valve seat.  
         [0010]     In accordance with another embodiment of the present invention, an inkjet printing component is described that includes: (a) an ink reservoir including: (i) an ink exit orifice at a first elevation, (ii) a gaseous exit orifice at a second elevation, where the second elevation is higher than the first elevation, (iii) a gas accumulation area in fluid communication with the gaseous exit orifice; (b) an ink filter in fluid communication with an interior of the ink reservoir; and (c) a pump assembly operative to withdraw gas through the gaseous exit orifice and from the gas accumulation area and subsequently inhibit fluid communication between the withdrawn gas and the interior of the ink reservoir.  
         [0011]     In another embodiment, the ink reservoir includes an ink entrance orifice at a third elevation, the ink filter is in series with the ink entrance orifice, and the second elevation is higher than the third elevation. In still another more detailed embodiment, the ink reservoir includes a first inlet coupling adapted to interface with a first outlet coupling of a replacement ink tank, where the replacement ink tank is laterally coupled to the ink reservoir.  
         [0012]     Another embodiment of the invention describes a method of increasing the longevity of a printhead, the method comprising displacing gas within an ink reservoir, where the gas displaced was located downstream from an ink filter, where the act of displacing the gas includes implementing a gas accumulation area within the ink reservoir.  
         [0013]     In yet another embodiment, the act of displacing the gas includes withdrawing the gas from within the ink reservoir and inhibiting fluid communication between the gas withdrawn and liquid ink within the ink reservoir, and the act of withdrawing the gas from within the ink reservoir includes opening a check valve to provide fluid communication between the gas accumulation area and a gas containment area. In still another more detailed embodiment, the method further comprises pumping the withdrawn gas into an area not in fluid communication with the ink reservoir.  
         [0014]     Another embodiment pertains to a method of removing gas in fluid communication with an ink reservoir, the method comprising purging gas from a gas accumulation area of an ink reservoir, where purging act includes manipulating a valve assembly downstream from an ink filter, the valve assembly operative to separate the gas accumulation area of the ink reservoir from an external environment, the valve assembly operative to facilitate unidirectional volumetric flow of the gas between the gas accumulation area and the external environment. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is an exploded view of a first exemplary printhead in accordance with the present invention;  
         [0016]      FIG. 2  is an overhead view of a first exemplary printhead body in accordance with the present invention;  
         [0017]      FIG. 3  is a cross-sectional view from the side of the first exemplary printhead of  FIG. 1 ;  
         [0018]      FIG. 4  is an exploded view of a second exemplary printhead in accordance with the present invention;  
         [0019]      FIG. 5  is a cross-sectional view the second exemplary printhead of  FIG. 4 ; and  
         [0020]      FIG. 6  is an isolated cross-sectional view of a second alternate exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0021]     The exemplary embodiments of the present invention are described and illustrated below to encompass devices and methods to reduce the likelihood of gaseous blockages within the concourse of a printhead. 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 features and steps that one of ordinary skill will recognize as not being a requisite to fall within the scope of the present invention.  
         [0022]     Referencing  FIGS. 1-3 , a first exemplary printhead  10  includes a printhead body  12  adapted to have a removable ink tank cartridge  14  mounted thereto. The printhead body  12  includes an outer housing  16  that includes a recessed area  18  partially occupied by a plurality of local ink reservoirs  20 . A via  22  at the bottom of each reservoir provides fluid communication between the interior of each reservoir and one or more nozzles  24  associated with a nozzle plate  26  mounted to the underside of the printhead body  12  partially defining the recessed area  18  (floor).  
         [0023]     In this exemplary embodiment, the ink reservoirs  20  occupy a rectangular area that is subdivided to provide two L-shaped (in horizontal cross-section) towers  32 ,  34  and a smaller rectangular tower  36  therebetween. The interior volume of each tower  32 ,  34 ,  36  is defined by the floor of the recessed area  18 , a set of vertical walls  38 , and a tower cap  40 . The underside  42  of the tower cap  40  receives the top portion of the vertical walls of the towers  32 ,  34 ,  36  and provides a fluidic seal separating the interior regions of one tower from another. One vertical wall  38  of each tower  32 ,  34 ,  36  includes an opening  46  adapted to provide ink to the interior of each tower. The opening  46  is bounded by a conduit  48  extending radially outward from each tower and includes an ink filter  50  in series therewith. In this exemplary embodiment, the ink filter  50  is mounted to the mouth  51  of the conduit  48 . However, those of ordinary skill will understand that the filter  50  may be mounted in other locations, so long as the functionality of filtering the ink is preserved.  
         [0024]     The mouth  51  of each conduit  48  is adapted to interface the removable ink tank cartridge  14 . In this exemplary embodiment, the removable ink tank cartridge  14  comprises three fluidicly separate ink tanks  52 ,  54 ,  56  that may, for example, respectively house yellow, magenta, and cyan colored inks. Each ink tank  52 ,  54 ,  56  includes an interior region  58  adapted to be occupied by felt or foam (not shown) loaded with ink that is generally bounded by the exterior walls  60  of the cartridge  14 , an interior vertical wall  62  spanning the length of the cartridge and extending to meet the floor of the cartridge, and a tank lid  64 . Each interior region  58  includes a tapered floor portion  66  that is operative to direct ink through the felt or foam and toward an exit orifice (not shown) associated with each tank  52 ,  54 ,  56  as the level of ink drops from usage. The exit orifice of each tank  52 ,  54 ,  56  is adapted to be in fluid communication with its respective conduit  48  associated with one of the towers  32 ,  34 ,  36  of the printhead  12 .  
         [0025]     An exemplary installation of the removable ink tank cartridge  14  to the printhead body  12  includes orienting and aligning the exit orifices with respect to the conduits  48 . The floor of the printhead body  12  includes rails  70  adapted to be received by grooves  72  within the underside of the cartridge  14  to inhibit rotation of the cartridge  14  with respect to the printhead body  12 , thereby facilitating horizontal sliding of the cartridge  14  upon the floor of the printhead body  12  until the cartridge  14  abuts the body  12  such that the conduits  48  fluidicly seal with respect to the exit orifices. The fluidic seal between the conduits  48  and exit orifices is operative to inhibit gaseous flow into the conduit by way of the interface between the conduits  48  and orifices. Those of ordinary skill are familiar with the techniques for carrying out such fluidic interfaces by providing a sealing member such as a circumferential O-ring between two adjacent surfaces that are separated by the sealing member. Those of ordinary skill are also familiar with the techniques for inhibiting ink from exiting the tanks prematurely by way of unintended capillary action that include, without limitation, positioning a removable thin film over the exit orifices.  
         [0026]     Upon mounting the cartridge  14  to the body  12 , a fluid communication system is provided enabling ink to flow from a tank  52 ,  54 ,  56  into a respective tower  32 ,  34 ,  36 . Those of ordinary skill are aware that mounting a cartridge  14  to a body  12  may be operative to introduce vapor into the tower. In addition, vapor may accumulate within the tower as a result of normal printing operations and as a result of dissolved vapor coming out of solution. In each of these cases, vapor accumulation may detract from printhead longevity. The first exemplary embodiment  10  manages vapor accumulation by providing a vertically oriented filter  50  and providing a vapor accumulation area  74  within each tower  32 ,  34 ,  36 .  
         [0027]     Vapor bubbles that are small enough to pass through the filter  50  are generally drawn into the ink conduit and accumulate within one of the tower  32 ,  34 ,  36 . However, some vapor bubbles may be too large to pass through the filter  50  and may become an impediment to ink flow therethrough. Prior art ink filters positioned horizontally would trap such relatively large vapor bubbles as the buoyancy of the bubble attempted to drive the bubbles upward through the ink until being stopped by the underside of the filter. A vertically oriented filter  50  (i.e., orienting the active filter surface on a plane generally parallel to a vertical plane), on the other hand, minimizes the resistance to upward flow of the vapor bubbles. In addition, by providing a vapor accumulation area  74  within each tower  32 ,  34 ,  36  that is vertically elevated with respect to the position of the ink filter  50 , vapor bubbles gravitate to the highest vertical point within the tower. In this manner, vapor may accumulate above the level of ink within each tower  32 ,  34 ,  36  without substantially impairing the flow of ink through each conduit  48 .  
         [0028]     Referencing  FIGS. 4 and 5 , a second exemplary printhead  100  includes a printhead body  102  adapted to interface with a removable ink tank cartridge  104 . The printhead body  102  includes an outer housing  106  that includes a recessed area  108  partially occupied by local ink reservoirs  110 . A via  112  at the bottom of each reservoir provides fluid communication between the interior of each reservoir and one or more nozzles  114  associated with a nozzle plate  116  mounted to the underside of the printhead body  102  partially defining the recessed area  108  (floor).  
         [0029]     In this second exemplary embodiment, the ink reservoirs  10  occupy a rectangular area that is subdivided to provide two L-shaped towers (not shown) and a smaller rectangular tower (not shown) therebetween. The interior volume of each tower is defined by the floor of the recessed area  108 , a set of vertical walls  117 , and a tower cap  118 . The underside  120  of the tower cap  118  receives the top portion of the vertical walls  117  of the towers and provides a fluidic seal separating the interior region of one tower from another. The underside  120  of the tower cap  118  also includes three chambers  122 , one for each tower. Each chamber  122  includes an orifice  124  in a side wall thereof in fluid communication with a vapor accumulation area  126  of each tower. The tower cap  118  also includes three orifices  128  in a triangular configuration extending into a respective vapor accumulation area  126  of each tower. The orifices  128  are aligned with three orifices  130  within a purge seal  132 . The orifices  130  of the purge seal  132  are tapered inward from top to bottom and are adapted to receive check balls  134  biased against the purge seal  132  by cut-outs of a spring disc  136 . A purge bulb  138  is positioned over the spring disc  136  and a purge housing  140  is positioned over the purge bulb  138 . A printhead lid  142  is positioned over the housing  140  and operative to press an annular ring  144  of the housing  140  against an annular flange  146  of the bulb  138 , which pushes against a circumferential portion  148  of the spring disc  136 , which, in turn, pushes against a circumferential portion  150  of the purge seal  132  to compress the purge seal  132  against the tower cap  118  and provide a series of fluidic seals. In sum, the first seal is between the circumferential portion  150  of the purge seal  132  and the tower cap  118 , the second seal is between the circumferential portion  150  of the purge seal  132  and the circumferential portion  148  of the spring disc  136 , the third seal is between the annular flange  146  of the bulb  138  and the circumferential portion  148  of the spring disc  136 , and the fourth seal is between the annular flange  146  of the bulb  138  and the annular ring  144  of the housing  140 .  
         [0030]     The purge housing  140  also includes a radially extending conduit  152  in fluid communication with the interior of the bulb  138 . The conduit houses a vent seal  154  in series with a check ball  156 . A conduit cap  160  is mounted to the end of the conduit  152 , with a spring  158  being wedged between the conduit cap  160  and the ball  156 . The conduit cap  160  provides a relatively rigid point against which the spring  158  pushes, therefore biasing the ball  156  against the seal  154  when the bulb  138  is in its inflated state (See  FIG. 5 ).  
         [0031]     One vertical wall  117  of each tower includes an opening  170  adapted to provide an orifice through which ink enters a conduit  172  to enter each tower. The conduit is oriented to extend away from each tower and includes an ink filter  174  in series therewith. In this exemplary embodiment, the ink filter  174  is mounted to the mouth of the conduit  172 , however, it is to be understood that the precise location of the ink filter may be changed without departing from the scope and spirit of the present invention.  
         [0032]     The mouth of each conduit  172  is adapted to interface with the removable ink tank cartridge  104 . In this exemplary embodiment, the removable ink tank cartridge  104  comprises three fluidicly separate ink tanks  176 ,  178 ,  180  that may, for example, respectively house yellow, magenta, and cyan colored inks. Each ink tank  176 ,  178 ,  180  includes an interior region  182  adapted to be occupied by felt or foam (now shown) loaded with ink that is generally bounded by the exterior walls  184  of the cartridge, an interior vertical wall  185  spanning the length of the cartridge and extending to meet the floor of the cartridge, and a tank lid  186 . Each interior region  182  of the tank cartridge includes an exit orifice (not shown) adapted to be in fluid communication with its corresponding conduit  172  associated with one of the towers of the printhead.  
         [0033]     An exemplary installation of the removable ink tank cartridge  104  to the printhead body  102  includes orienting and aligning the exit orifices with respect to the conduits  172 . The floor of the printhead body  102  includes rails  190  adapted to be received by grooves  192  within the underside of the cartridge  104  to inhibit rotation of the cartridge  104  with respect to the printhead body  102 , thereby facilitating horizontal sliding of the cartridge  104  upon the floor of the printhead body  102  until the cartridge  104  abuts the body  102  such that the conduits  172  fluidicly seal with respect to the exit orifices. The fluidic seal between the conduits  172  and exit orifices is operative to inhibit gaseous flow into the conduit by way of the interface between the conduits  172  and orifices. Those of ordinary skill are familiar with the techniques for carrying out such fluidic interfaces such as providing a circumferential O-ring. Those of ordinary skill are also familiar with the techniques for inhibiting ink from exiting from the tanks  176 ,  178 ,  180  prematurely from unintended capillary action that include, without limitation, positioning a removable or pierceable thin film over the exit orifice.  
         [0034]     Upon mounting the cartridge  104  to the body  102 , a fluid communication system is provided enabling ink to flow from the tanks  176 ,  178 ,  180  into the towers. Those of ordinary skill are aware that mounting a cartridge  104  to a body  102  may be operative to introduce vapor into the tower. In addition, vapor may accumulate within a tower as a result of normal printing operations and as a result of dissolved vapor coming out of solution. In each of these cases, vapor accumulation may degrade the longevity of the printhead. The second exemplary embodiment  100  manages vapor accumulation by providing vertically oriented filters  174  within conduits  172 ; providing a vapor accumulation area  126  within each tank  176 ,  178 ,  180  positioned above and in fluid communication with the filter  174 ; and providing a purge system to remove vapor present within the vapor accumulation area  126 .  
         [0035]     Referencing  FIGS. 4 and 5 , an exemplary operation of the purge system of the printhead  100  will be discussed below. For purposes of illustration, it is presumed that the ink tank cartridge  104  has been mounted to the printhead body  102  to provide a fluidic interface between the towers of the printhead and the tanks  176 ,  178 ,  180  of the cartridge  104 .  
         [0036]     Vapor present within any of the towers will be directed upward to the vapor accumulation area  126 . For purposes of illustration, accumulated vapor within a tower is shown as a black oval labeled “VAPOR”. The amount of vapor within the accumulation area  126 , in this exemplary illustration, pushes the level of ink within the tower below the height of the orifice  124  within the chamber  122 . To reduce the vapor within the towers, the bulb  138  is actuated from an inflated state to a deflated state. Actuation of the bulb  138  results from a downward force applied to the exterior of the bulb  138 , such as, without limitation, by a user pushing his finger against the bulb  138 . It is to be understood that the description of the bulb  138  in an inflated state or a deflated state is comparative in nature and refers to positions of the bulb where the interior area defined by the walls of the bulb  138  is either decreased (deflated) or increased (inflated). Thus, an inflated state only means that the interior area of the bulb  138  can be further decreased, and the deflated states only means that the interior area of the bulb  138  can be further increased, comparatively speaking. The actuation of the bulb  138  from an inflated state to a deflated state forces gas from the interior of the bulb  138  and creates a temporary region of higher pressure gas pushing against each of the check balls  134 ,  156 . The higher pressure gas pushes the check balls  134  against the purge seal  132  and is operative to form a seal therebetween, thereby inhibiting the higher pressure gas from passing into the chambers  122 . However, this higher pressure gas provides a force pushing against the ball  156  sufficient to overcome the bias of the spring  158  and dislodge the ball  156  from the vent seal  154  to enable the gas to pass through the conduit  152  and into an external environment. As gas escapes into the external environment, the pressure acting on the ball  156  decreases and at a certain point, the pressure of the gas is no longer great enough to overcome the bias of the spring  158 . When this occurs, the ball  156  is forced against the vent seal  154  and seals off the external environment from the gas within the system. The bulb  138  at this point is roughly in a deflated state, and it is within the scope and spirit of the present invention that the bulb  138  be comprised of a resilient material. The resiliency of the bulb  138  results in the bulb attempting to return to its inflated state, which provides a lower pressure area approximate the check balls  134 . The pressure differential across the check balls  134  is operative to displace one or more of the balls and allow higher pressure vapor/gas from the chambers  122  to flow through one or more of the orifices  128  within the tower cap  118  and through one or more orifices  130  of the purge seal  132  and into the interior inflated area of the bulb  138 . The orifice  124  of each chamber  122  is adapted to be positioned adjacent to the top height of the tower so that nearly all of the vapor within the tower is extracted before ink is drawn into the chamber. As ink is drawn into the chamber  122  and elevates to reach the check ball  134 , the wetting effect between the ink, ball  134 , and seal  132  is operative to provide a seal such that vapor from the other towers will be extracted prior to ink passing beyond the ball  134 . In this manner, vapor within each tower may be concurrently extracted by a single purging operation.  
         [0037]     Referencing  FIG. 6 , it is also within the scope of the present invention to provide a float  200  within each chamber  122  that is operative to abut the orifice  128  in the tower cap  118  and seal off the opening, thereby prohibiting liquid ink from reaching the check ball  134 . In this manner, as ink is drawn into the chamber  122 , via the orifice  124 , the float  200  would ride upon the level of ink within the chamber  122 . As the level of ink rises within the chamber  122 , the float  200  is operative to abut the orifice  128  and form a seal therebetween to discontinue fluid communication between the chamber  122  and the interior of the bulb  138 . Those of ordinary skill will understand the numerous options for providing a float  200  within the chamber  122 , such as providing holes  202  through the float  200  to allow the buoyant nature of the float  200  to rise to the top of the ink, even when ink is deposited on top of the float  200 .  
         [0038]     It is also within the scope of the present invention to automate the purging system by providing an automated mechanical ram operative to deflate the bulb  138  and purge gases from within the reservoirs. Those of ordinary skill are familiar with exemplary automated systems that could provide the necessary mechanical deflection the bulb in order to provide a purging sequence based upon the current disclosure.  
         [0039]     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.