Patent Publication Number: US-6705711-B1

Title: Methods, systems, and devices for controlling ink delivery to one or more print heads

Description:
BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates generally to controlling the delivery of ink to one or more print heads and, more specifically, generally relates to controlling the pressure of ink delivered to one or more print heads from an ink reservoir. 
     2. The Relevant Technology 
     Printing devices, such as ink-jet printing devices, are well known and available from various manufacturers. A typical ink-jet printing device includes multiple print heads mounted on a movable carriage. Each print head contains one or more ink-jet nozzles through which ink is delivered during a printing process. For instance, as the movable carriage is repeatedly scanned back and forth across a printable medium, such as a paper sheet, the ink-jet nozzles in the various print heads are activated to lay or deliver drops of ink on the printable medium at precise locations. In typical color printing, between four and six different colors of ink are deposited over an area by multiple heads, in successive scans across the sheet. 
     Following a print pass, relative movement between the printing device and the medium is provided. This relative movement enables a different portion of the medium to be printed during each subsequent scan. As those skilled in the art will appreciate, the nozzles on each of the multiple print heads must be controlled to deposit ink drops in precise locations relative to drops deposited by the other print heads. The control of the ink delivered from the nozzles has a profound effect upon the quality of images created by ink jet printers. 
     To maintain high quality while depositing ink at fast rates, it is important that all deposited ink drops have substantially the same volume so that all printed drops are consistent in size. When the volume of deposited ink is either excessive or insufficient, differences in the printed image are perceptible. These differences in the printed image quality may occur when a meniscus of the ink at one or more nozzles extends beyond the boundaries of the specific nozzle to encroach upon one or more of the surrounding nozzles. The encroaching of the ink results in excessive ink deposited upon printable media during a print process, thereby reducing the image quality. Further, the excessive ink can solidify over one or more of the nozzles and prevent ink from being deposited upon printable media during a printing process. Again, this reduces the image quality of the printed image. 
     Additionally, differences in printed image quality can occur when the meniscus of ink at a nozzle becomes concave and extends inwardly through the nozzle and into the print head. When this occurs, insufficient ink is deposited from the print head, resulting in decreased image quality. Furthermore, when a curvature of the meniscus exceeds specific limits governed by the surface tension characteristics of the ink and the adhesion of the ink to the nozzle, the meniscus can break. When the meniscus breaks, ink “drools” from the nozzle before, after and during a printing process. This again results in reduced image quality of the printed image. 
     Many attempts have been made to control the volume of ink deposited from the print nozzles. Further, many attempts have been made to control the curvature of the meniscus of the ink at the nozzles to prevent insufficient or excessive amounts of ink from being deposited upon printable media during a printing process. 
     In numerous ink-jet printers, ink is delivered to each print head by a tube that connects the print head to an ink reservoir positioned above the vertical level of the print head. During the printing process, ink flows along the tube to the nozzle of the print head under the force of gravity as the weight of the ink within the ink reservoir forces the ink stored in the tubing toward the nozzles. The volume of ink forced to each nozzle depends upon the particular volume of ink stored in the ink reservoir, fluid dynamic characteristics of the tubing, and chemical characteristics or properties of the ink. For instance, when an ink having a high absolute viscosity is employed with a printing device, a low volume of ink is forced to a nozzle under a given pressure. Similarly, when an ink having a low absolute viscosity is employed with a printing device a high volume of ink is forced to a nozzle under the same given pressure. Changes to the chemical composition of the ink causes changes in the effectiveness of these gravity-type ink-jet printers. Therefore, these ink-jet printers are difficult to use with a variety of different inks. 
     Other ink jet printers utilize a surge suppressor to pressurize the ink as it is passed into the ink reservoir. The surge suppressor maintains an average pressure within the tube connecting the ink reservoir with the print head. Typically, the surge suppressor used in such ink-jet printers is designed for a particular ink, with associated characteristics and properties. Additionally, surge suppressors are typically not adjustable and allow large ranges of pressure fluctuations. 
     Consequently, it would be an advance in the art to provide systems and methods that maintain high quality image reproduction through control of the volume of ink deposited from a nozzle of a print head. Further, it would be an advance in the art to provide systems and methods that control the curvature of the meniscus, while preventing insufficient or excessive deposit of ink during a printing process. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the invention as embodied and broadly described herein, a printing system capable of delivering ink to printable media is disclosed. One particular printing system includes a printing device that communicates with a vacuum pump and a remote main ink reservoir. During a printing process, the remote main ink reservoir delivers ink to the printing device to maintain the ink stored in an ink reservoir of the printing device within selected tolerances. Meanwhile, the vacuum pump creates a vacuum or partial vacuum within the ink reservoir to maintain a pressure of the ink within selected tolerances so that the ink is delivered from a print head during the printing process. Through operation of the vacuum pump, the pressure exerted by the ink at one or more nozzles of the print head is maintained with desired tolerances no matter the particular volume of ink stored within the ink reservoir. Consequently, the potential for excessive or insufficient delivery of ink from the print head is reduced or eliminated. 
     According to one aspect of one embodiment of the present invention, a provided printing device includes a housing with a printer head carriage mounted to and slidable upon a track. The printer head carriage supports one or more ink reservoirs that communicate with a vacuum pump and a remote main ink reservoir. Disposed within one or more of the ink reservoirs are sensors to identify a level of ink and a vacuum or partial vacuum level within the one or more ink reservoir. These sensors send signals indicative of the sensed levels to a controller that is adapted to control the operation of the vacuum pump and an ink pump associated with the remote main ink reservoir to maintain the level of ink and the vacuum or partial vacuum level within desired tolerances. 
     According to another aspect of one embodiment of the present invention, a printing device communicates with an accumulator, which is disposed between the printing device and the vacuum pump. The accumulator functions to increase the resolution, the accuracy, and the precision of the vacuum pump. In this manner, the printing system can accurately control the vacuum or partial vacuum level within the ink reservoir and hence maintain the pressure of the ink at the one or more nozzles of the one or more print heads. 
     According to another aspect of one embodiment of the present invention, a printing system includes a vacuum pump that communicates with an ink reservoir of the printing device. The vacuum pump can degas the ink stored within or communicating with the ink reservoir to allow gas dissolved within the ink to migrate to and escape from a surface of the ink. This can be achieved, in one configuration, by creating a vacuum or partial vacuum within the ink reservoir. 
     According to another aspect of one embodiment of the present invention, a printing system is adapted to accommodate the use of multiple types of ink. The printing system includes a vacuum pump that is used to control the level of a vacuum or partial vacuum within an ink reservoir. A controller changes a level of vacuum or partial vacuum based upon the level of ink within the ink reservoir to achieve a desired pressure at one or more nozzles of one or more print heads. The inks used within the printing system can each have different chemical compositions and hence different flow characteristics that govern the manner in which the ink flows from the ink reservoir, along one or more tubes, to the one or more print heads. When ink reservoirs with a second type of ink are substituted for ink reservoirs with a first type of ink, the controller can vary the level of vacuum or partial vacuum to accommodate for changes in ink characteristics between the first and second types of ink, such as but not limited to, changes in adhesions, surface tension, viscosity, or other characteristics of the inks. 
     According to another aspect of one embodiment of the present invention, by creating a vacuum or partial vacuum within an ink reservoir, a printing system can control the size, shape, and configuration of a meniscus of the ink formed at one or more nozzles of one or more print heads. In addition to the degree of attraction of the ink to the material forming the nozzles and the surface tension characteristics of the ink, the curvature of the meniscus is affected by the pressure exerted by the column of ink extending from the nozzle to the exposed surface of the ink within the ink reservoir. Through varying the level of the vacuum or partial vacuum within the ink reservoir, embodiments of the printing system can change the curvature of the meniscus to control the volume of ink to be delivered from the nozzles and limit the meniscus from rupturing or extending onto the outer surface of the print head. 
     These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 illustrates a perspective view of an exemplary printer device of a printing system in accordance with one embodiment of the present invention; 
     FIG. 2 illustrates a perspective view of an exemplary printer head carriage and track of the printer device of FIG. 1 in accordance with one embodiment of the present invention; 
     FIG. 3 illustrates an exploded perspective view of a printer head carriage of the printer device of FIG. 1 in accordance with one embodiment of the present invention; 
     FIG. 4 illustrates a perspective view of an exemplary reservoir, print head, control board and associated communicating tubes and ribbons forming part of the printer head carriage of FIG. 1 in accordance with one embodiment of the present invention; 
     FIG. 5 illustrates partial cross-sectional side view of the exemplary reservoir, print head, control board and associated communicating tubes and ribbons forming part of the printer head carriage of FIG. 1 in accordance with one embodiment of the present invention; 
     FIG. 6 illustrates a cross-sectional side view of an exemplary print head, including one or more nozzles, of the printer device of FIG. 1 in accordance with one embodiment of the present invention; 
     FIG. 7 illustrates a schematic representation of an exemplary printing system of one embodiment of the present invention; and 
     FIG. 8 illustrates a schematic representation of another exemplary printing system of one embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention relates to systems, methods and apparatus for delivering ink to one or more print heads. Embodiments of illustrative systems, methods and apparatus of the present invention facilitate ink delivery to one or more nozzles of one or more print heads, while the pressure exerted by the ink at one or more nozzles is maintained within defined tolerances. By maintaining the pressure of the ink within defined tolerances, embodiments of the present invention provide a mechanism for correctly delivering a volume of ink to thereby limit the potential for depositing excessive or insufficient quantities of ink upon printable media. Therefore, through providing mechanisms for controlling the delivery or deposit of ink from one or more print heads, embodiments of the present invention can improve the quality of the perceived color and clarity of print images. 
     According to another aspect of one embodiment of the present invention, a vacuum or partial vacuum is created within an ink reservoir that stores the ink to be delivered from a print head. The vacuum or partial vacuum aids with controlling a pressure exerted by the ink at one or more nozzles of the print head. The level of the vacuum or partial vacuum within the ink reservoir can be changed to control the pressure of the ink at the one or more nozzles of the print head. By so doing, embodiments of the present invention provide a mechanism to control the volume of ink delivered through the one or more nozzles of the print head and maintain the operability of the print head. 
     Through providing control of the vacuum or partial vacuum level within the reservoir, an embodiment of the present invention provides systems, methods, and apparatus that can accommodate a variety of inks having differing characteristics and properties without the need for significant expense and time associated with testing of the particular system or device for each particular ink. Further, control of the vacuum or partial vacuum level provides a mechanism to control the size, shape, and configuration of a meniscus of the ink formed at one or more nozzles of one or more print heads. Changes to the curvature of the meniscus can control the volume of ink discharged from the nozzles of the print head during a printing process. 
     As used herein, the terms “vacuum” and “partial vacuum” refer to a pressure that is lower than ambient pressure or atmospheric pressure for a particular geographic location of the print system or device of the present invention. The terms “vacuum” and “partial vacuum” are used interchangeably to refer to pressures below or deviation from ambient pressure or atmospheric pressure. 
     Another embodiment of the systems, methods, and apparatus provide mechanisms for degassing inks used within the printing systems or devices. By so doing, the systems, methods, and apparatus reduce the requirement for expensive and complicated degassing equipment, as is typically the case with existing printing systems. 
     The following discussion of illustrative systems, methods, and apparatus of the present invention will be directed to large format printing systems and devices. One skilled in the art, however, can appreciate that the teachings of the present invention can be utilized in various other types of printing systems or devices, ranging from small home use printers or systems to other large commercial printers or systems. Further, although reference is made to the use of ink, it can be understood that structures and functions of the present invention can be used in any situation where a pressure of a fluid is controlled by varying a level of a vacuum or partial vacuum within a container storing the particular fluid. The fluid with the container can be in a liquid or gaseous state. 
     Referring now to FIG. 1, depicted is an exemplary configuration of one printing system of the present invention. The printing system  8  includes a printing device  10  and a main ink reservoir, a controller, and a vacuum source (not shown). The printing system  8  is capable of delivering ink to a printable media. The inks can include, but not limited to, an air-dry pigmented liquid, a heat dry pigmented liquid, an ultraviolet curable pigmented liquid, absorbable liquid, or other type of ink capable of being delivered by one or more print heads. In another configuration, printing system  8  is capable of delivering other fluids through associated print heads, such as but not limited to fluids for etching glass, metallic fluids to be deposited on a media, or any other fluid that may be deposited from a nozzle and receive a benefit from the teaching of the present invention. 
     Printing device  10  includes a housing  12  that retains various components and control mechanisms of printing device  10 , only some of which will be described herein for ease of explanation of the present invention, while others will be understood by those skilled in the art in light of the teaching contained herein. 
     Disposed within housing  12  is a printer head carriage  14  that is movably mounted to a track  18  of printing device  10 . The printer head carriage  14  moves back and forth along track  18  and allows delivery of ink from one or more print heads  20   a - 20   n  mounted to printer head carriage  14 , as illustrated in FIG.  2 . Relative movement of printer head carriage  14  along track  18  can occur through various driving mechanisms. For instance, the driving mechanism can include, but not limited to, hydraulic or pneumatic driver mechanisms, mechanical driver mechanisms, chain or belt and driven sprocket mechanisms, combinations thereof, or other types of driving mechanism that are capable of performing the function of moving the printer head carriage along a track. 
     With reference to FIG. 2, depicted is a partially assembled printer head carriage  14 . A support structure  30  forms part of printer head carriage  14 . This support structure  30  slidably cooperates with track  18  and includes one or more wheels  32  to allow printer head carriage  14  to be moved along track  18  under the influence of the driving mechanism. Although reference is made to the use of wheels, it can be understood that printer head carriage  14  can includes various other mechanisms that are capable of performing the function of aiding to move printer head carriage  14  along track  18 . The above are exemplary structures capable of performing the function of means for moving one or more printer heads during a printing process. Further, the discussed structures are capable of performing the function of means for moving a printer head carriage along a track. 
     In addition to cooperating with track  18 , support structure  30  securely retains a print head support  38  that securely retains print heads  20   a - 20   n  in releasable engagement therewith. With reference to FIG. 3, print head support  38  includes a plurality of apertures  34   a - 34   n,  each of which is configured to maintain a print head  20   a - 20   n  (FIG. 2) in an upright or substantially vertical orientation. By maintaining print heads  20   a - 20   n  (FIG. 2) in the desired orientation, the ink can be accurately deposited or delivered upon printable media, such as but not limited to, a cellulose media, a plastic media, a metallic media, a synthetic media, silk media, canvas media, paper media, textile material, a media formed form one or more naturally occurring substances, a media formed from one or more synthetic substances, combinations thereof, or other media that is capable of receiving ink delivered from the print heads during a printing process. Apertures  34   a — 34   a  of print head support  38  cooperate with print heads  20   a - 20   n  (FIG. 2) to allow releasable engagement between the same. Therefore, print heads  20   a - 20   n  (FIG. 2) and apertures  34   a - 34   n  can have various complementary configurations that are capable of performing the function of releasably engaging one with another. Stated another way, print head support  38 , whether alone or in combination with print heads  20   a - 20   n  (FIG.  2 ), includes structures that are capable of performing the function of means for engaging one or more print heads with a support. Illustratively, and not by way of limitation, such structures can include slip-fit or snap fit mechanism to releasably or permanently attaching each print head  20   a - 20   n  (FIG. 2) within a respective aperture  34   a - 34   n . Alternatively, each print head  20   a - 20   n  is maintained in within respective apertures  34   a - 34   n  through one or more fasteners, such as any fastener that is capable of performing the function of or act as a means for engaging a print head to a support. 
     Returning to FIG. 2, mounted to support structure  30  is a reservoir support  36 . The reservoir support  36 , as seen in FIGS. 2 and 3, receives one or more reservoirs  40   a - 40   n  that store ink to be delivered from print heads  20   a - 20   n  to printable media (not shown). For instance, reservoir support  36  can receive an ink reservoir with one type of ink and subsequently receive another ink reservoir with another similar or dissimilar ink. 
     Each side  42  and  44  of reservoir support  36  includes one or more recesses  46  and  48  respectively. A recess  46  cooperates with one end of a single reservoir  40   a , for instance, while recess  48  cooperates with the opposite end of reservoir  40   a . The particular configuration of recesses  46  and  48  is such that reservoirs  40   a - 40   n  disposed therein are maintained a distance from print heads  20   a - 20   n  when the same are disposed within apertures  34   a - 34   n . Further, the configuration of each recess  46  and  48  aids with securely retaining the respective reservoir  40   a - 40   n  disposed therein. 
     Reservoir support  36  is one structure capable of performing the function of means for supporting one or more reservoirs. The reservoir support  36  or means for supporting can have various configurations. For instance, and not by way of limitation, each recess  46  and  48  can cooperate with structures or fasteners formed on each reservoir  40   a - 40   n  to cause releasable and/or permanent engagement between reservoir  40   a - 40   n  and reservoir support  36 . Alternatively, each reservoir  40   a - 40   n  can cooperate with structures or fasteners associated with each recess  46  and/or  48  to cause releasable and/or permanent engagement between reservoir  40   a - 40   n  and reservoir support  36 . 
     Mounted to support structure  30  is control board  50 . The control board  50  provides an interface between print heads  20   a - 20   n  and the control systems and circuitry (not show) of printing device  10  (FIG. 1) and/or printing system  8  of the present invention. In one configuration, as shown in FIG. 4, control board  50  includes a connector  52  that mates with the corresponding connector  54  on ribbon wire  56 . This ribbon wire  56  extends from control board  50  to an individual print head, such as print head  20   a  and allows signals to be transmitted from control board  50  to initiate the delivery of ink from each print head  20   a - 20   n . The control board and ribbon wire are illustrative of one structure capable of performing the function of means for delivering control signals to a print head. Once skilled in the art can identify a variety of other configuration. For instance, in another configuration, a plurality of electrical conductors extends from control board  50  to print heads  20   a - 20   n . In still another configuration, wireless or infrared technology is used to deliver signals to print heads  20   a - 20   n.    
     With continued reference to FIG. 4, depicted is an illustrative configuration of the various components and control connections associated with one ink reservoir and one print head. Although the following discussion relates to a single reservoir and one print head and those components communicating or connected thereto, a similar discussion may be made for multiple reservoirs and multiple associated components. 
     As illustrated, reservoir  40   a  includes a housing  60  with an interior space  80 . The interior space  80  of reservoir  40   a  is adapted to store a quantity or volume of ink that can be delivered to one or more print heads  20   a - 20   n . In one configuration, reservoir  40   a  stores about 2 milliliters to about 1000 milliliters of ink. In another configuration, reservoir  40   a  stores about 2 milliliters to about 100 milliliters of ink, while in another configuration reservoir  40   a  stores about 2 milliliters to about 3 milliliters of ink. Consequently, reservoir  40   a  can have a width of about 0.125 inches to about 4 inches. In an alternate configuration, reservoir  40   a  can have a width of about 0.125 inches to about 1 inch. In still another configuration, reservoir  40   a  can have a width of about 0.125 inches to about 0.250 inches. 
     The housing  60  of reservoir  40   a  includes engagement mechanisms  62  and  64  disposed at ends  66  and  68  respectively. In this particular configuration, each engagement mechanism  62  and  64  includes a leg  70  extending from respective end  66  or  68 . Each leg  70  is biased to extend from respective end  66  or  68 , while is capable of being temporarily moved toward end  66  or  68  as reservoir  40   a  engages or disengages with reservoir support  36 . A step portion  72  formed in leg  70  cooperates with recess  46  or  48  (FIG. 3) of reservoir support  36  to prevent inadvertent removal of reservoir  40   a  from reservoir support  36 . When leg  70  is moved toward end  66  or  68 , step portion  72  disengages from reservoir support  36  and releases reservoir  40   a  therefrom. Each engagement mechanism  62  and  64 , therefore, cooperates with a respective recess  46  and  48  (FIG. 3) of reservoir support  36  to securely retain reservoir  40   a  in the desired position relative to print heads  20   a - 20   n.    
     The engagement mechanism described above is one structure capable of performing the function of means for coupling a reservoir to a support. One skilled in the art can identify a variety of other configurations of engagement mechanism and hence means for coupling. For instance, in other configurations, engagement mechanisms can be configured to cause snap-fit engagement, slip-fit engagement, friction-fit engagement, releasable fastener engagement, where a fastener is capable of performing the function of releasably attaching a reservoir to a support, or some other engagement mechanism capable of acting as means for coupling a reservoir to a support. In still other configurations, engagement mechanisms can cause permanent engagement through, but not limited to, adhesives, thermal bonds, chemical bonds, welds, or other fastener, methods, techniques, or structures capable of permanently attaching one or more reservoirs to a support. When permanent engagement occurs between one or more reservoirs and a support, replacing used reservoirs occurs through replacing the reservoirs and support with another support with either permanently or releasably attached reservoirs. 
     In another configuration, reservoir  40   a  includes one or more engagement mechanisms. In still another configuration, reservoir support  36  (FIG. 3) can include one or more engagement mechanisms, while reservoir  40   a  cooperates with reservoir support  36 . In another configuration, each end  66  and  68  of reservoir  40   a  can be configured with a respective recess, while recesses  46  and  48  can include complementary engagement mechanism(s). In still another configuration, ends  66  and  68  cooperate with reservoir support  36  (FIG. 3) through fasteners or other structures formed in the reservoir and/or reservoir support that are capable of performing the function of attaching the reservoir to the reservoir support. 
     Referring again to FIG. 3, disposed at end  68  of reservoir  40   a  is a port  74 , which receives a sensor device  76  (FIG.  4 ). As shown in FIG. 4, sensor device  76  can be releasably mounted in port  74  so that sensor device  76  can be removed from port  74  when reservoir  40   a  is replaced within another reservoir having similar or dissimilar ink therein. 
     Port  74  cooperates with sensor device  76  such that sensor device  76  cooperates with a sensor  78  located within an interior space  80  of reservoir  40   a , as illustrated in FIG.  5 . As depicted, sensor  78  may have the configuration of a float-type fluid level sensor, however, various other types of sensor can be used within embodiments of the present invention. For instance, in another configuration, an optical sensor can be used to detect the level of the ink within reservoir  40   a . In another configuration, one or more thermistors are used to identify the temperature within reservoir  40   a  the temperature within reservoir  40   a  being related to the quantity of ink within interior space  80  of reservoir  40   a . Using the detected temperature, the volume of ink within reservoir  40   a  can be identified. In another configuration, a sensor is used to detect the mass of ink within reservoir  40   a  the mass of ink being used to define the volume of ink within reservoir  40 . Generally, any type of sensor that is capable of identifying a level of a fluid contained within a container, such as but not limited to a reservoir, can be used to act as sensor device  76  and/or sensor  78 . 
     Sensor device  76  cooperates with sensor  78  to receive signals indicating the ink level of the ink within interior space  80  of reservoir  40   a . Upon receiving the signals, sensor  78  delivers those signals to the controller via a wire, cable, optical fiber, wireless transmitters and receivers, or other structure or devices capable of performing the function of delivering signals indicative of an ink level to the controller. In another configuration, sensor device  76  is eliminated and sensor  78  communicates directly with the controller. 
     The sensor is an example of a structure capable of performing the function of means for identifying a level of fluid within a reservoir. Further, the sensor in combination with the sensor device is another example of a structure capable of performing the function of means for identifying a level of fluid within a reservoir. Additionally, the sensor device alone is another example of a structure capable of performing the function of means for identifying a level of fluid within a reservoir. In addition to the above, one skilled in the art can identify various other structures that are capable of performing this desired function. 
     Referring to both FIGS. 4 and 5, the illustrative housing  60  of reservoir  40   a  includes four ink outlets  90   a - 90   d . These outlets  90   a - 90   d  are adapted to facilitate delivery of ink from reservoir  40   a  to print head  20   a . More specifically, outlets  90   a - 90   d  provide a fluid path between reservoir  40   a  and one or more tubes  92   a - 92   n  communicating with print heads  20   a - 20   n , only print head  20   a  being depicted in FIGS. 4 and 5. Although reference is made to four outlets  90   a - 90   n , one skilled in the art can appreciate that housing  60  can include one or more outlets. 
     In this particular configuration, and illustrated in FIG. 5, each outlet  90   a - 90   d  includes an aperture  94   a - 94   n  within housing  60 , only apertures  94   a  and  94   b  are depicted. Disposed within each aperture  94   a - 94   n  is a connector  96   a - 96   n , only connectors  96   a  and  96   b  are depicted in FIG.  5 . Each connector  96   a - 96   d  includes threads that engage with complementary threads formed in respective apertures  94   a - 94   d  of housing  60  to create a fluid path between reservoir  40   a  and tubes  92   a - 92   d  attached to respective connectors  92   a - 92   d . In an alternate configuration, each connector  96   a - 96   d  slip-fits or snap-fits within respective apertures  94   a - 94   n  formed in housing  60  of reservoir  40   a . In still another configuration, each connector  96   a - 96   d  can be integrally formed with housing  60  of reservoir  40   a.    
     As illustrated in FIGS. 4 and 5, tubes  92   a - 92   d  connect to outlets  90   a - 90   n . By connecting outlets  90   a - 90   n  to tube  92   a - 92   n , tubes  92   a - 92   n  provide a fluid pathway for the ink with interior space  80  of housing  60  and respective print heads  20   a - 20   n . In this exemplary configuration, a proximal end  98   a  of each tube  92   a - 92   d  connects to one of outlets  90   a - 90   d , while a distal end  98   b  of each tube  92   a - 92   d  connects to a print heads  20   a - 20   n . Alternatively, a proximal end  98   a  of each tube  92   a - 92   d  can connect to one or more outlets  90   a - 90   d , while distal end  98   b  of each tube  92   a - 92   d  can connect to one or more print heads  20   a - 20   n . The tubes  92   a - 92   d  are examples of structures capable of performing the function, whether alone or in combination with one or more of the structures described herein, of means for providing a fluid pathway between a reservoir and a print head. Other structures are known to those skilled in the art in light of the teaching contained herein. 
     Turning to FIG. 5, each tube  92   a - 92   d  can have an inside diameter from about ¼ inch to about {fraction (1/32)} inch. In another configuration, each tube  92   a - 92   d  has an inside diameter of about {fraction (3/32)} inch. As with the number of ink outlets formed in reservoir  40   a,  one or more tubes can be used with different configurations of the present invention. 
     Disposed at a distal end  98   b  of tube  92   a  is a print head  20   a . Similarly, but not shown, disposed at the distal ends of the tubes are the print heads. An exemplary print head  20   a  includes a body  100  that has an interior chamber  102  and one or more nozzles  140   a - 140   n  disposed in body  100  that communicate with interior chamber  102 . In this exemplary configuration, ink passes from tube  92   a , for example, to interior chamber  102  via lumens  110 ,  112 ,  114  associated respectively with a connector  104 , an intermediate tube  106 , and a port connector  108  of print head  20   a . These lumens  110 ,  112 ,  114  create a fluid pathway for the ink to traverse from reservoir  40   a  to interior chamber  102 , before the ink is delivered from nozzles  140   a - 140   n.    
     Although reference is made to specific lumens  110 ,  112 , and  114  associated with connector  104 , intermediate tube  106 , and port connector  108  of print head  20   a,  one skilled in the art can appreciate that various other configurations of the present invention are possible, so long as ink can traverse a fluid pathway from reservoir  40   a  to print head  20   a . More generally, the above-described lumens of the print head are structures capable of performing the function, whether alone or in combination with one or more of the structures described herein, of means for providing a fluid pathway between a reservoir and a print head. An alternate configuration, and hence alternate means for providing a fluid pathway, utilizes a single lumen extending from reservoir  40   a  to print head  20   a  to form the desired fluid pathway. In still another configuration, multiple lumens form the fluid pathway from reservoir  40   a  to print head  20   a.    
     In addition to the above, lumens  110 ,  112 , and  114  associated with connector  104 , intermediate tube  106 , and port connector  108  of print head  20   a  are examples of structure capable of performing the function of means for delivering a volume of a fluid to printable media during a printing process. Furthermore, the connectors permanently or releasably attached to the reservoir, the one or more print heads, and the tubes connecting the print heads to the reservoir are exemplary structures capable of performing the function of means for delivering a volume of a fluid to printable media during a printing process. In still another configuration, the control board and ribbon connector are includes as exemplary structures capable of performing the function of means for delivering a volume of a fluid to printable media during a printing process. Other structure capable of assisting with or forming part of the means for delivering a volume of a fluid to printable media during a printing process are known to one skilled in the art in light of the teaching contained herein. 
     With continued reference to FIG. 5, generally, body  100  of print head  20   a  is adapted to securely retain circuitry and associated piezo-electric components used to deliver ink during a printing process. Although reference is made to print head  20   a  using piezo-electric components and technology to deliver ink during a printing process, one skilled in the art can identify various other components and technologies that are capable of delivering ink from the print heads, such as but not limited to, components associated with thermal printing technologies, electrical printing technologies, solid ink technologies, or other printing technologies known to those skilled in the art. 
     In addition to outlets  90   a - 90   d , reservoir  40   a  includes an ink inlet  120 . The ink inlet  120  communicates with a remote main ink reservoir  210  (FIG. 7) by a tube  122 . The remote main ink reservoir  210  contains a volume of ink that can be added to reservoir  40   a  as ink is delivered to print head  20   a  during a printing process. In this manner, ink extends continuously and completely between portions of reservoir  40   a , outlet  90   a,  tube  92   a , and along the fluid pathway defined by lumens  110 ,  112 , and  114  to interior chamber  102  and nozzles  140   a - 140   n.    
     At nozzles  140   a - 140   n , the ink from reservoir  40   a  forms a meniscus  124  or interface between the ink and nozzles  140   a - 140   n , as shown in FIGS. 5 and 6. The curvature of meniscus  124  is controlled by the degree of attraction of the ink to the material forming nozzles  140   a - 140   n  and the surface tension characteristics of the ink. Additionally, the curvature of meniscus  124  is affected by the pressure exerted by the ink above the vertical level of nozzles  140   a - 140   n  because the pressure exerted by the ink at nozzles  140   a - 140   n  is based upon the difference in vertical height between nozzles  140   a - 140   n  and the vertical level of the ink within reservoir  40   a . In the event that the attraction of the ink to the material forming nozzles  140   a - 140   n  is exceeded, the surface tension characteristics changed, or the pressure exceeds a certain level, the curvature of meniscus  124  will be changed so that meniscus  124  has a convex configuration and extends beyond the limits of nozzles  140   a - 140   n , as depicted by dotted lines A. The extended meniscus  124  can cause print head  20   a  to deliver a volume of ink greater than is needed during a printing process, resulting in excessive deposit of ink, incorrect mixing of inks, and poor image quality. In some instances, the extended meniscus will encroach upon adjacent nozzles, thereby preventing the effective delivery of ink from one or more nozzles  140   a - 140   n.    
     In the event that the pressure is lower than a certain level, there is a potential for ambient pressure to be sufficient to force meniscus  124  to have a concave configuration, as depicted by dotted line B. Further, if the pressure is lower than a certain level, there is a potential for the ambient pressure to be sufficient to overcome the attraction or surface tension characteristics of the ink, resulting in meniscus  124  rupturing, as depicted with nozzle  140   a  that is devoid of a meniscus. In such a case, the ink can flow freely through nozzle  140   a  and “drool” from the print head. The retracted or broken meniscus can cause print head  20   a  to deliver, respectively, either an insufficient volume of ink or a greater than needed volume of ink during a printing process. In both cases, incorrect mixing of inks and poor image quality occurs. 
     Maintaining the desired ink pressure is achieved by maintaining the volume of ink within selected tolerances, such tolerances being based upon the particular ink and its associated characteristics and/or properties. By maintaining the level of ink within reservoir  40   a  within the proscribed tolerances, the pressure of the ink is maintained within desired tolerances and the correct volume of ink is delivered from the print heads during a printing process. Additionally, the pressure is sufficient to prevent rupturing of meniscus  124  and/or extending meniscus  124  beyond desired limits. 
     The deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink at nozzles  140   a - 140   n  can be from about −5 inches of water to about 20 inches of water, when measured at about 60° F. In another configuration, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink at nozzles  140   a - 140   n  can be from about 3 inches of water to about 10 inches of water. In still another configuration, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink at nozzles  140   a - 140   n  can be from about 6 inches of water to about 8 inches of water. In another configuration, pressure exerted by the ink at nozzles  140   a - 140   n  can be substantially equal to ambient pressure or atmospheric pressure. 
     Stated another way, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink can ranges from about −9.34 torr to about 37.37 torr. In another configuration, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink at nozzles  140   a - 140   n  can be from about 5.60 torr to about 18.68 torr. In still another configuration, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink at nozzles  140   a - 140   n  can be from about 11.21 torr to about 14.95 torr. In another configuration, the pressure exerted at nozzles  140   a - 140   n  is substantially equal to ambient pressure or atmospheric pressure. 
     Stated another way, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink can range from about −0.18 PSI to about 0.72 PSI. In another configuration, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink at nozzles  140   a - 140   n  can be from about 0.11 PSI to about 0.36 PSI. In still another configuration, the deviation from ambient pressure or atmospheric pressure of the pressure exerted by the ink at nozzles  140   a - 140   n  can be from about 0.22 PSI to about 0.29 PSI. In another configuration, the pressure exerted at nozzles  140   a - 140   n  is substantially equal to ambient pressure or atmospheric pressure. 
     To aid in maintaining the desired pressure, housing  60  of reservoir  40   a  includes an inlet  130 , shown in FIG. 5, which communicates with a vacuum source (not shown) via a tube  132 . The vacuum source is schematically illustrated in FIG.  7 . The vacuum source, such as but not limited to a vacuum pump, a vacuum pump in combination with an accumulator, a vacuum pump with air bleed, combinations, thereof, or other device capable of producing a vacuum or partial vacuum within reservoir  40   a . This vacuum can be varied based upon the particular volume of ink within the reservoir, the properties and characteristics of the ink, the temperature of the ink, desired curvature of the meniscus of the ink at one or more of the nozzles of one or more print heads, to thereby maintain the pressure of the ink within the desired tolerances. 
     By creating a vacuum or partial vacuum within the reservoir, the column of ink extending from the reservoir to the nozzles of the print heads are “drawn” upwardly away from the nozzles, thereby changing the pressure exerted by the ink at the nozzles of the print heads. This “drawing” effect also allows printing system  8  to control the volume of ink disposed at the print heads and the curvature of the meniscus at each nozzle. Further, changing the level of the vacuum or partial vacuum allows printing system  8  to accommodate a variety of different inks. This is achieved by mitigating the fluid dynamic and chemical properties of the ink and materials forming the reservoir, the tubes, and the print heads through changing the level of the vacuum or partial vacuum to thereby maintain the pressure at the nozzles within a desired level where each meniscus neither ruptures nor extends outwardly from respective nozzles. 
     Additional components and systems of printing system  10  of one embodiments of the present invention are schematically depicted in FIG.  7 . The following description will be directed to a single reservoir and one or more print heads. One skilled in the art can understand that a similar discussion can be made for multiple reservoirs and associated multiple print heads. 
     As shown, printing system  200  includes reservoir  206  that is in fluid communication with print head  20   a,  in a similar manner as described above. Reservoir  206  can have a similar configuration to reservoir  40   a  described above. 
     The reservoir  206  fluidly communicates with a remote main ink reservoir  210  through appropriate tubes or other structures capable of functioning to deliver ink from one reservoir to another reservoir. The main ink reservoir  210  can be any type of container that is capable of storing ink. Consequently, main ink reservoir  210  is one example of structure capable of performing the function of means for remotely storing a fluid. 
     Main ink reservoir  210  includes an outlet that provides the ink to reservoir  206  as ink is delivered to print heads  20   a - 20   n  before, during, or subsequent to a pass of printer head carriage  14  (FIGS. 1 and 2) of the print media during the printing process. As the printing process progresses, i.e., ink is delivered from one or more of print heads  20   a - 20   n  to printable media, the level of ink within reservoir  206  may come close to falling outside of defined tolerance levels. One tolerance level defines a maximum volume of ink to be maintained within reservoir  206 , while another tolerance level defines a minimum volume of ink to be maintained within reservoir  206 . These tolerance levels can have values that are either the same or different one from another. For instance, in one configuration, if we define a level  214  as a median of a tolerance range, the actual ink level can be maintained within a range of about +/−1 inch. In another configuration, the actual ink level can be maintained within a range of about +/−½ inch. In still another configuration, the actual ink level can be maintained within a range of about +/−⅛ inch from level  214 . Stated another way, the actual ink level of the ink remains within +/−2.54 centimeters from level  214 . In another configuration, the actual ink level can be maintained within a range of about +/−1.27 centimeters from level  214 . In still another configuration, the actual ink level can be maintained within a range of about +/−0.32 centimeters from level  214 . These tolerances can be maintained during the printing process and/or refilling of reservoir  206 . 
     To maintain the ink level within the above-identified tolerances, ink is delivered to reservoir  40   a  from main ink reservoir  210  under the command of controller  208 , such as one or more mechanical devices, hydraulic devices, pneumatic devices, electrical devices, optical devices, or combinations of such devices. Ink delivery occurs when a sensor  216  with in reservoir  206  delivers a signal to controller  208  that indicates the level of ink within reservoir  206 . The controller  208  can analyze the signal and determine whether that the ink level is outside of tolerance or becoming close to being outside tolerance. Based upon this determination, controller  208  can activate a pump  218 , disposed either within main ink reservoir  210  or external to main ink reservoir  201 , to force ink into reservoir  206 . 
     In another configuration, sensor  216  can deliver a signal indicating that the level of the ink is becoming close to or currently exceeds a defined tolerance. In response to receiving such a signal, controller  208  can activate pump  218  to force or deliver ink to reservoir  206  to place the level of ink within tolerances. 
     Therefore, controller  208 , whether alone or in combination with one or more of the structures defined herein, such as but not limited to one or more sensors, sensor devices, control boards, ink reservoirs, and/or ink pumps, is one structure capable of performing the function of means for varying a level of a fluid within a reservoir or container. One skilled in the art can identify a variety of other structures that are capable of performing this desired function. 
     In addition to receiving signal indicating the level of ink within reservoir  206 , controller  208  can communicate with a sensor  220  that is disposed in either accumulator  204  or reservoir  206  to sense the particular a level of the vacuum or partial vacuum therein. The sensor  220  can be a pressure sensor, a precision pressure sensor, or some other sensor capable of detecting the level of vacuum or partial vacuum within reservoir  206  and/or accumulator  204 . This sensor  220  is one structure capable of performing the function of means for identifying a level of a vacuum or partial vacuum. One skilled in the art can identify various other configurations of the sensor that are capable of performing the desired function. 
     Whether sensor  220  identifies a level of a vacuum or partial vacuum within accumulator  204  and/or reservoir  206 , controller  208  can utilize the sensed level of the vacuum or partial vacuum either alone or in combination with the sensed level of the ink to identify changes to be made to the level of the vacuum or partial vacuum and corresponding signals to be sent to vacuum pump  202  and/or ink pump  218 . Alternatively, controller  208  can utilize the sensed level of the ink alone to identify changes to be made to the level of the vacuum or partial vacuum and thereafter generate signals to be sent to vacuum pump  202  and/or ink pump  218  to change the level of the vacuum or partial vacuum within reservoir  206 . Therefore, controller  208 , whether alone or in combination with one or more of the structures defined herein, such as but not limited to one or more sensors, sensor devices, control boards, vacuum pumps, and/or accumulators, is one structure capable of performing the function of means for varying the level of the vacuum or partial vacuum within a reservoir. 
     The vacuum pump  202  is configured to move air from within reservoir  206  and accumulator  204  under the command of controller  208 . The vacuum pump  202  can remove air from reservoir  206   a  and/or accumulator  204  or alternatively move air from within reservoir  206  to accumulator  204 . In the latter case, vacuum pump  202  can create changes in the level of the vacuum or partial vacuum within reservoir  206  by causing air molecules to compress together or allowing air molecules to separate one from another. 
     Communicating with vacuum pump  202  is accumulator  204 . The accumulator  204  aids with creating and changing the level of the vacuum or partial vacuum within reservoir  206 . The accumulator  204  is disposed between vacuum pump  202  and reservoir  206  and functions to increase the resolution, the accuracy, and the precision of vacuum pump  202 . By providing a large volume of air or other fluid within accumulator  204 , the pumping effects of vacuum pump  202  are translated into small, incremental changes in the level of the vacuum or partial vacuum within reservoir  206 . Consequently, the combination of vacuum pump  202  and accumulator  204  can maintain the level of the vacuum or partial vacuum within reservoir  206  to achieve the desired pressure of the ink at the nozzles (not shown) of print head  20   a.    
     The vacuum pump, either alone or in combination with the accumulator, are exemplary structures capable of performing the function of means for creating a vacuum or partial vacuum within a reservoir. One skilled in the art can identify various other structures that are capable of performing this desired function. Further, the accumulator is one structure capable of performing the function of means for increasing the precision of a vacuum pump. One skilled in the art can identify various other structures that are capable of performing this desired function. For instance, in another configuration, a vacuum pump with a regulated air bleed can function as the vacuum pump. 
     Illustratively, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum in reservoir  206  by vacuum pump  202  and/or accumulator  204  can range from about +/−3 inches of water to about +/−60 inches of water. In another configuration, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−1 inch of water to about +/−30 inches of water. In still another configuration, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−6 inches of water to about +/−8 inches of water. 
     Stated another way, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−5.60 torr to about +/−111.99 torr. In another configuration, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−1.87 torr to about +/−55.99 torr. In still another configuration, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−11.21 torr to about +/−14.97 torr. 
     Stated in still another way, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−0.11 PSI to about +/−2.17 PSI. In another configuration, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−0.04 PSI to about +/−1.08 PSI. In still another configuration, the deviation from ambient pressure or atmospheric pressure causing the vacuum or partial vacuum within reservoir  206  can range from about +/−0.22 PSI to about +/−0.29 PSI. 
     By creating a vacuum or partial vacuum within reservoir  206 , vacuum pump  202  and/or accumulator  204  reduce the pressure of ink at the nozzles, such pressure being associated with the height difference between the vertical height of the nozzles and the vertical height of the level of ink within reservoir  206 . Effectively, a pressure differential is created between reservoir  206  and the pressure at the nozzles, the pressure at the nozzles, in one embodiment being substantially the same as ambient or atmospheric pressure. Illustratively, the difference in pressure between reservoir  206  and ambient or atmospheric pressure is small enough that the adhesion properties and surface tension of the ink maintains meniscus as ambient air attempts to move through the nozzles. The pressure difference can be varied to control the pressure of ink at the nozzles. 
     Through controlling the pressure of ink at the nozzles, the potential for excessive or insufficient delivery of ink from the nozzles is reduced. Additionally, by controlling the pressure at the nozzles, the curvature of meniscus is controlled; thereby changing the volume of ink delivered from each the nozzle during a printing process. Further, the system can accommodate inks having differing properties and characteristics, such as but not limited to, adhesion characteristics, attraction characteristics, surface tension, temperature dependent properties, or other properties or characteristics of the ink or fluid. For instance, the system can be used to perform a printing process using a first ink in a first reservoir and subsequently used to print using a second ink in a second reservoir. The system can operate with a particular level of a vacuum or partial vacuum and associated ink levels for the first ink and subsequently operate at another level of a vacuum or partial vacuum based upon the ink level and the characteristics and properties of the second ink. Through changing the level of the vacuum or partial vacuum generated by the pump, alone or in combination with the accumulator, the same system can operate using multiple different inks in an efficient manner. With only one variable being changed, the time and money associated with testing of new ink or inks not previously tested with a particular system or printing device are reduced. 
     This is an advance over existing systems because large sums of money and time must currently be spent in testing differing inks with differing systems to achieve high quality printer output. When new inks or inks not previously tested with a particular system or printing device are to be used with a particular system or device, the manufacturer of the ink and/or system or device must spend numerous hours and large amounts of money to verify that the system or device can print using the proposed ink. Further, the ink or system/device manufacturer must identify usage parameters specific to the ink and system or device, such parameters taking many hours and large quantities of money to generate. In many cases, the systems and/or devices must also be modified to accommodate the new or proposed ink. 
     According to another aspect of one embodiment of the invention, through creating a vacuum or partial vacuum within reservoir  206 , system  200  also degasses the ink within reservoir  206  before the ink is delivered to print head  20   a . Since a vacuum or partial vacuum is created in reservoir  206 , any dissolved gases within the ink migrate to the upper surface of the ink and are drawn out of the ink. In many circumstances, inks are degassed to remove oxygen and other gases dissolved within the ink. Removing the unwanted gases, limits the potential for gas bubbles to flow with the ink to print heads  20   a - 20   n . In the event that a gas bubble were to reach print heads  20   a - 20   n , the bubble could prevent ink from being delivered therefrom, resulting in an inoperable print head. Additionally, removing gas bubbles aids with maintaining a consistent ink pressure. Since gas bubbles within the ink are compressible, the pressure of the ink can vary based upon the particular compressibility characteristics of the gas forming the bubble. Hence, the ink pressure may not be accurately maintained within the desired tolerances and the resultant print quality may be reduced when the ink includes dissolved gases. Therefore, vacuum pump  202 , either alone or in combination with accumulator  204 , is one structure capable of performing the function of means for degassing a fluid. One skilled in the art in can identify other structures capable of performing this function. 
     Referring now to FIG. 8, another configuration of one system of the present invention is depicted. The discussion of the features of the other systems described herein is equally applicable to system  250 . Consequently, only changes between system  200  and  250  will be discussed herein. 
     As illustrated, system  250  includes a pump  252  that directly communicates with reservoir  206  and controller  208 . In this configuration, pump  252  optionally includes the capabilities of accumulator  204  and/or is capable of making small changes in the level of the vacuum or partial vacuum within reservoir  206 . As with system  200 , pump  252  can operate under the command of controller  208 . Consequently, pump  252  is one structure capable of performing the function of means for creating a vacuum or partial vacuum within a reservoir and means for degassing a fluid. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.