Abstract:
A modular ink jet ink delivery system comprising a print manifold including a passageway therethrough for the transfer of ink and a pen tower removably and operatively engageable with the manifold. The pen tower includes a central passageway for receiving and transferring ink from the manifold. A retainer member is operatively connected to the manifold. A first sealing member forms a first seal with the retainer member. A second sealing member forms a second seal with the pen tower such that when the pen tower and the manifold are operatively engaged with each other, a substantially sealed passageway is formed for the transfer of ink from the manifold to the pen tower.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to seals for an ink jet ink delivery system. More particularly, the present invention relates to a fluid interconnect seal for a modular ink jet ink delivery system. 
   BACKGROUND OF THE INVENTION 
   A typical ink jet printer has a print head mounted to a carriage that is moved back and forth over a print media, such as paper. As the print head passes over appropriate locations on the printing surface, a control system selectively activates the print head to eject, or jet, ink drops onto the print media to form images and text characters. 
   To work properly, such printers must have a reliable supply of ink for the print head. One type of ink jet printer makes use a disposable ink pen that can be mounted to the carriage. Such an ink pen typically includes, in addition to the print head, a reservoir containing a supply of ink. The ink pen also typically includes pressure regulating mechanisms to maintain the ink supply at an appropriate pressure for use by the print head. When the ink supply is exhausted, the ink pen is disposed of and a new ink pen is installed. 
   Other types of ink jet printers make use of ink container portions that are separately replaceable from a print head portion. For this type of printing system the print head portion can include a pressure regulating mechanism to maintain proper operating pressure. The ink container portion may be mounted away from the carriage or mounted on the carriage. In either case, it is very important that the replaceable ink container and printer be capable of establishing a reliable fluid connection therebetween. This fluid interconnection should be capable of repeated disconnects and reconnects as the ink container is removed and reinstalled. For the case of ink delivery systems where differential pressure exists between ink passages and atmosphere the fluid interconnect should be robust enough to prevent leakage under normal operating pressures (positive or negative with respect to atmosphere) as well as under various environmental conditions the printer and ink containers are specified to experience either operating or non-operating. 
   Such an ink jet ink delivery system, also referred to as an IDS, often employs modular designs which frequently contain separate user-replaceable components for the ink supply cartridges and for the print head cartridges. In some designs an intermediate manifold or tubing system is used to transport ink from the ink supply cartridge to a print head cartridge. 
   Previous fluid interconnect designs have incorporated a single annular compliant face seal around each foam/screen fluid interconnect interface where the manifold connects to the print head cartridge. These seals may be subject to leaks (primarily air leaks). These leaks may especially occur if foreign materials or defects are present at the sealing interface. Air leaks at these interfaces may allow volatile components to evaporate from the ink or even allow the ink within the ink delivery system to dry out completely. Over extended printer usage, a small air leak can allow the print head cartridge to fill with air (as air replaces the ink the print cartridge is attempting to draw). This can cause the print head to deprime and prevent further printing. 
   SUMMARY OF THE INVENTION 
   One aspect of the present invention provides for a modular ink jet ink delivery system comprising a print manifold including a passageway therethrough for the transfer of ink and a pen tower removably and operatively engageable with the manifold. The pen tower includes a central passageway for receiving and transferring ink from the manifold. A retainer member is operatively connected to the manifold. A first sealing member is operatively connected to the pen tower and forms a first seal with the retainer member. A second sealing member is operatively connected to the retainer member and forms a second seal with the pen tower such that when the pen tower and the manifold are operatively engaged with each other, a redundantly sealed passageway is formed for the transfer of ink from the manifold to the pen tower. 
   Another aspect of the invention provides for an ink delivery system comprising an ink reservoir, a manifold assembly including a passageway for receiving and transferring ink from the ink reservoir, and a pen tower removably and operatively engageable with the manifold. A first sealing member is operatively connected to the manifold assembly and forms a first seal with the pen tower when the pen tower is operatively engaged to the manifold assembly. A second sealing member is operatively connected to the pen tower and forms a second seal with the manifold assembly when the pen tower is operatively engaged to the manifold assembly. 
   Another aspect of the present invention provides for a modular ink jet delivery system comprising a manifold including a passageway therethrough for the passage of ink and a pen tower removably and operatively engageable with the manifold, the pen tower including a passageway for receiving and transferring ink from the manifold. A retainer member is fixedly connected to the manifold, and first sealing means are operatively connected to the retainer member. The first sealing means form a seal with the pen tower when the pen tower is operatively engaged with the manifold. Second sealing means are operatively connected to the pen tower. The second sealing means form a second seal with the retainer member when the pen tower is operatively engaged with the manifold, providing for redundant seals along the ink passageway. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a sectional side view of a modular ink delivery system according to one embodiment of the invention; 
       FIG. 2  is an enlarged sectional side view of the ink delivery system of  FIG. 1  showing the ink pathway through the system; 
       FIG. 3  is a further enlarged sectional and side view of system of  FIG. 1 ; 
       FIG. 4  is a sectional side view of an alternate embodiment of the invention incorporating a radial seal along the outer diameter of the pen tower; 
       FIG. 5  is a sectional side view of another embodiment of the invention, where a radial seal is formed at the end of a flexible needle along the inner diameter of the pen tower; 
       FIG. 6A  is a sectional side view of an embodiment of the invention wherein a flexible needle forms a seal with the inner diameter of the pen tower and includes a check valve that closes the flexible needle when the seal is disengaged; 
       FIG. 6B  is a sectional side view of another embodiment of the invention using a flexible needle to form a seal with the inner diameter of the pen tower and includes two check valves that close both the flexible needle and the pen tower when the seal is disengaged; 
       FIG. 7A  is a sectional side view of yet another embodiment of the invention using a check valve, wherein the elastomer housing is separated from the pen tower; 
       FIG. 7B  is a sectional side view of yet another embodiment of the invention using a check valve, wherein the elastomer housing is in contact with the pen tower; 
       FIG. 8  is a sectional side view of still another embodiment of the invention using an elastomer skin and capture ring for an inner seal; and 
       FIG. 9  is a sectional side view of another embodiment of the invention, wherein a compliant disk contacts the pen tower when the pen tower and the manifold are engaged. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention replaces a foam/screen fluid interconnect where a manifold or manifold assembly connects to a print head cartridge with a face seal. The foam/screen interface in previous designs is prone to allow air to be ingested by the ink delivery system if its annular compliant seal is compromised. The impact of air leaks at an ink delivery system sealing interface can be reduced significantly by adding a secondary seal at the interface, especially when the secondary seal is wetted. 
   The present invention can be incorporated into a modular ink delivery system of the type shown in  FIGS. 1-3 , wherein an ink-routing manifold  20  connects to a pen tower  36  located on a print head cartridge  42 . In the ink delivery system, shown generally at  18 , an ink supply cartridge or reservoir  40  provides ink, the path of which is shown at  24 , through the manifold  20 . The manifold  20  routes the ink to the print head cartridge  42 . At each of the connections of the ink supply cartridge or reservoir  40  to the manifold  20  and the manifold  20  to the print head cartridge  42 , a foam/screen fluid interconnect was previously used. A single annular compliant seal around the foam/screen interface was incorporated to reduce ink evaporation and air gain at these interfaces. This type of system is always under negative pressure relative to atmosphere and so is subject to ingesting air if any leaks in the system exist. 
   In order to prevent such deleterious occurrences, a redundant inner seal  26  is incorporated with an outer seal  34 . The redundant inner seal  26  replaces the foam/screen fluid interconnect with a first face seal  32 . When the manifold  20  is brought into contact with the print head cartridge  42 , a pen tower  36  is pressed against the exposed face of the inner seal  26 , providing the first face seal  32  at this interface. In one embodiment of the invention, the inner seal  26  may comprise an elastomer integrated into the manifold  20  and bound to it by an inner seal retainer  28  which is connected to the manifold  20  to form the manifold assembly ( 20  and  28 ) of the modular ink delivery system  18 . In one embodiment of the invention, the inner seal retainer  28  is welded to the manifold  20 , although other coupling methods may also be used. 
   A gland-style seal  22  is formed at the interface of the manifold  20  and the inner seal  26 , although other sealing methods could also be used without departing from the invention&#39;s broader aspects. Once ink is pulled along the pathway  24  and through the manifold  20  to the print head cartridge  42 , the first face seal  32  at the inner seal/tower interface becomes wet with ink. This provides a more effective seal than would occur by using a dry face seal. The gland seal  22 , although starting dry, may also become a wetted seal. 
   The outer seal  34  comprises an elastomer installed on the print head cartridge tower  36 , forming a radial seal  38  to the tower. The outer seal  34  also provides a second face seal  30  when brought into contact with the inner seal retainer  28 . The second face seal  30  may also be made more effective if wetted either by ink or by use of a separate sealant. When the second face seal  30  becomes a wetted seal, this wetted seal will aid with pen air gain in the event that the first face seal  32  or other part of the outer seal  34  is compromised. 
   In the embodiment shown in  FIGS. 1-3 , the first and second face seals  30  and  32  are employed to minimize any transverse forces between components of the ink delivery system  18  caused by axial misalignment of the components. Excessive axial or transverse forces on the print head cartridge  42  can affect its alignment relative to the print medium or relative to the other print cartridges in the carriage and therefore adversely affect the resultant print quality. This embodiment also allows the fluid interconnect to be connected and disconnected multiple times without significant performance loss due to aging of the components. 
   Additionally, the ink delivery system  18  shown in  FIGS. 1-3  may include a rolling diaphragm-type seal  27  between the inner seal  26  and the inner seal retainer  28 . The rolling diaphragm-type seal  27  operates to minimize forces imparted to the pen while the fluid interconnect is being engaged, thereby helping maintain proper pen alignment with respect to its datum features and not degrading print quality. 
   In an alternate embodiment of the invention, it may also be possible to use a liquid film, such as a film of polyethylene glycol (PEG), at the first face seal  32  prior to use. The use of such a liquid film can improve the overall sealing effectiveness during the manifold startup process. 
   In an embodiment of the invention shown in  FIG. 4 , a radial seal  60  is formed along the outer diameter of the pen tower  36  and inner sealing material  62 . As in the embodiment shown in  FIGS. 1-3 , the second face seal  30  is formed between the inner seal retainer  28  and the outer seal  34 . When the manifold  20  is brought into contact with the print head cartridge  42 , the upper portion of the pen tower  36  slides through the radial seal  60 . A gland-style seal arrangement  22  is formed at the interface between the manifold  20  and the first face seal  32 . Once again, when ink travels through the pathway  24  and is pulled through the manifold  20  to the print head cartridge  42 , the radial seal  60  becomes wet with ink, providing a more effective seal than would occur by using a dry face seal. 
     FIGS. 5-9  show alternate embodiments of the invention. Each of these embodiments show alternative versions of the inner seal  26  of  FIGS. 1-4 . According to various embodiments of the invention, these different versions of the inner seal  26  of  FIGS. 1-4  would be used in addition to the outer seal  34  of  FIGS. 1-4  or a similar structure. The examples of seal types shown in  FIGS. 5-9  are for illustrative purposes only, and other types of seals could also be used without departing from the invention&#39;s broader aspects. 
     FIG. 5  shows another embodiment of the invention, wherein a radial seal  70  is formed along the inner diameter of the pen tower  36  by using a flexible elastomeric material that forms a flexible needle  72 . By forming the radial seal  70  inside and along the inner diameter of the pen tower  36 , it may be used with or without an outer seal as shown in  FIGS. 1-4 . When the manifold  20  is brought into contact with the print head cartridge  42 , the elastomeric material  72  slides through the inner diameter of the pen tower  36 , forming the radial seal  70 . In this embodiment of the invention, a gland seal  22  is formed between the inner seal retainer  28  and the elastomeric material  72 . It is also possible, however, for the gland seal  22  to be formed between the inner seal retainer  28  and the manifold  20 . Once ink is pulled along the pathway  24  and through the manifold  20  to the print head cartridge  42 , the radial seal  70  becomes wet with ink. This provides a more effective seal than would occur by using a dry seal. Transverse forces are low because the flexible needle  72  can flex and the seal  70  can pivot. Axial force is minimized because the sealing forces are radial and balance each other. 
   It is also possible to use methods other than face seals or radial seals in accordance with the present invention. For example and as shown in  FIGS. 6A and 6B , it is also possible to incorporate a one or two check valves  80  and  90  and flexible needle  88  inside the pen tower  36 . The check valves close to reduce ink leakage and air ingestion when the seal is disengaged. In the embodiment of the invention shown in  FIG. 6A , a check valve ball  82  is operatively connected to a spring  84 , both of which are located generally above a pin  86 . The needle  88  is forced into the pen tower  36 , causing the pin  86  to press the ball  82  upwards against the spring  84 , permitting the ink to flow. The pin  86  actuates the check valve  80 , while a seal  89  is formed between the flexible needle  88  and the inner walls of the surrounding pen tower  36 . In this embodiment, it is important that the weight of the check valve ball  82  plus the force from spring  84  is enough to overcome any back pressure from the ink supply. 
   The embodiment shown in  FIG. 6B  also uses a flexible needle  88  coupled to a check valve ball  82 . In this embodiment, however, there is a second check valve  90  comprising a pin  92 , a spring  91 , and a retainer  85  and ribs  87  positioned within the inner bore of the pen tower  36 . The operation of the seal  89  and the check valve  80  is similar to that of the embodiment described in FIG.  6 A. However in  FIG. 6B , the ball  82  presses on the pin  92  and spring  91  opening check valve  90 . Eventually pin  92  contacts ribs  87  and stops moving. Pin  92  now presses the ball  82  upwards against spring  84  permitting ink to flow through check valve  80 . 
     FIGS. 7A and 7B  show another embodiment of the invention. In this embodiment, a check valve  100  is placed inside an elastomer housing  102 . In one embodiment of the invention, the elastomer housing  102  is similar in structure to the inner seal  26  shown in  FIGS. 1-3 . A spring  104  is operatively connect to and located generally above the check valve  100 . In one embodiment of the invention, the check valve  100  comprises a plastic material, although other types of material may also be used. In this arrangement, when the manifold  20  is separated from the pen tower  36 , the use of the check valve  100  limits the degree of back flow. The limitation of the backflow results from the check valve  100  coming into contact with a contact surface  106  on the elastomer housing. The closed position is shown in FIG.  7 A. When the manifold  20  comes into contact with the pen tower  36 , the elastomer housing  102  deforms, pushing the check valve  100  against the spring  104  and upward relative to the manifold  20 . The open position is illustrated in  FIG. 7B , which shows an opening for an ink path around the lower edges of the check valve  100  and over the castellations in the upper surface of the elastomer housing  102 , i.e., when the manifold  20  is pushed up off the elastomer housing, then the castellations in the elastomer seal allow ink flow when the seal around the perimeter is open. This particular embodiment of the invention also includes the use of a gland seal  22  at the interface between the elastomer housing  102  and the inner seal retainer  28 . It is also possible for this gland seal  22  to be formed with the manifold  20 , however. 
     FIG. 8  shows still another embodiment of the invention. In this particular embodiment, an elastomer washer  110  is located on a contact surface  112  of a foam retainer  114 . A capture ring  116  is used to press-fit the outer edge of the elastomer washer  110 , forming a seal with the foam retainer  114 . The capture ring  116  is machine-formed according to one embodiment of the invention, although other methods of manufacturing the capture ring  116  are also possible. Additionally, it is also possible for the capture ring  116  to be glued to the elastomer washer  110  or for some other bonding method to be used. The pen tower  36  abuts against and partially deforms a portion of the elastomer washer  110  when the print head cartridge (not shown) is connected to the manifold  20 . In one embodiment of the invention, the elastomer washer  110  has a central hole  111  with a diameter of about one millimeter, although it is possible for the hole to have a diameter of a different size. 
   Yet another embodiment of the invention is shown in FIG.  9 . In this embodiment, a compliant foam disk  120  the pen tower  36  when the pen tower  36  and manifold  20  are engaged. When the pen tower  36  and the manifold  20  are engaged, a seal  122  is formed between the foam disk and the pen tower  36 . A small hole  124  is formed through the center of the disk  120 . The hole  124  allows for ink and air to flow freely into the pen tower  36 . An impermeable skin  126  is located on the top and bottom surfaces of the disk  120 . The skin  126  ensures a sufficient bubble pressure so as to prevent air from being ingested from outside the pen tower  36 . In one embodiment of the invention, open cell polyurethane foam with a skin of closed cell foam  126  is used to hold ink, to maintain the seal  122 , and to provide good compression set characteristics. 
   Additionally, it should also be noted that ink delivery systems are often shipped dry and primed with ink as the printer is started up. In systems in which ink is pulled through the ink delivery system, an air leak at any of the seals can prevent ink from being pulled from the ink supply cartridge, through the manifold, and into the print head cartridge causing the printer to fail to print. A redundant fluid interconnect seal reduces the possibility of an air leak during startup further ensuring the ink delivery system startup occurs successfully. 
   Overall print head and printer reliability can be improved by use of redundant fluid interconnect seals rather than a single seal in ink delivery systems in accordance with the present invention where modular ink-handling components are used. Specifically, with a redundant seal the probability of a complete sealing failure at a component-to-component sealing interface becomes the probability of having two seals fail rather than the probability of having a single seal failure. For example, if the probability of a seal failure in a single-seal design is 0.10 then the probability of having a complete sealing interface failure in a redundant-seal design using similar seals is 0.10×0.10 or 0.01, a factor of 10 improvement. 
   Additionally, the evaporation of solvents from the inks is slowed, maintaining their intended physical and chemical properties. This preventing changes in the quality of the printer output over time. Similarly, air gain by the ink delivery system under ideal sealing conditions is slowed, allowing for a longer print head cartridge life. Air gain by the ink delivery system in compromised sealing conditions (e.g. foreign material or molding defects are present at the sealing interface) is also reduced, allowing longer print head cartridge life. Air gain in cases where the ink delivery system is under negative pressure is reduced, and there is also a reduction in the number of failures of the ink delivery system to prime with ink as the printer is started up. 
   Furthermore, once ink is pulled through the ink delivery system, the face seal at the inner seal/pen tower interface becomes wetted with ink. This action provides for greater leak resistance than a similar dry seal. Lastly, once ink is pulled through the ink delivery system, the gland seal at the inner seal/manifold interface becomes wetted with ink. This provides a greater leak resistance than a similar dry seal. Additionally, the outer seal helps the inner seal to remain wetted, helps prevent it from being damaged, thus further improving the performance of the system. 
   While the preferred embodiments of the invention as implemented in a prototype system have been described, it will be understood by those skilled in the art to which the invention pertains that numerous modifications and changes may be made without departing from the true spirit and scope of the invention. For example, it is possible that different types of foams or other materials can be used for the individual sealing components, and it is also possible to position the individual seals in different locations. Furthermore, it may be possible to use face seals instead of radial seals or vice versa (or different types of seals altogether) in each of the embodiments described above. Additionally, although a number of materials are described as elastomer materials, other comparable types of materials could also be used without departing from the invention&#39;s broader aspects. The embodiments described herein are accordingly intended to define the scope of the invention precisely in the claims appended to and forming a part of this application.