Patent Publication Number: US-9849683-B2

Title: Ink port adapter for inkjet head

Description:
RELATED APPLICATIONS 
     This non-provisional patent application is a continuation-in-part of U.S. patent application Ser. No. 15/058,093 filed on Mar. 1, 2016, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The following disclosure relates to the field of printing, and in particular, to inkjet heads used in printing. 
     BACKGROUND 
     Inkjet printing is a type of printing that propels drops of ink (also referred to as droplets) onto a medium, such as paper, a substrate for 3D printing, etc. The core of an inkjet printer includes one or more print heads (referred to herein as inkjet heads) having multiple ink channels arranged in parallel to discharge droplets of ink. A typical ink channel includes a nozzle, a chamber, and a mechanism for ejecting the ink from the chamber and through the nozzle, which is typically a piezoelectric actuator connected to a diaphragm. To discharge a droplet from an ink channel, a drive circuit provides a drive waveform to the piezoelectric actuator of that ink channel that includes a jetting pulse. In response to the jetting pulse, the piezoelectric actuator generates pressure oscillations inside of the ink channel to push the droplet out of the nozzle. The drive waveforms provided to individual piezoelectric actuators control how droplets are ejected from each of the ink channels. 
     Inkjet heads are typically configured as single-color, two-color, or four-color heads. Users select the type of inkjet head based on their printing needs. For example, if a user has a need for both two-color and four-color printing, then they will select both a two-color and a four-color inkjet head. Users may therefore need to purchase multiple types of inkjet heads based their printing needs. 
     SUMMARY 
     Embodiments described herein include adapters for inkjet heads. The adapters as described herein may reduce the number of colors that are printed with an inkjet head. For example, an adapter may allow a two-color inkjet head to print in single-color. The adapters may reduce the number of connecting hoses that are needed to connect an inkjet head to an ink reservoir or return reservoir. Therefore, use of adapters as described herein advantageously gives users flexibility in how inkjet heads are used for printing. 
     One embodiment is an ink port adapter for an inkjet head. The ink port adapter comprises a body having a first surface and a second surface, a supply hose fitting that extends from the first surface of the body, a return hose fitting that extends from the first surface of the body, two supply openings on the second surface of the body, two return openings on the second surface of the body, a first ink path through the body that connects the supply hose fitting to the supply openings, a second ink path through the body that connects the return hose fitting to the return openings, and a bypass path that connects between the first ink path and the second ink path. 
     In another embodiment, the inkjet head includes a plurality of flow-through ink channels, and the bypass path has a higher fluid resistance than the flow-through ink channels of the inkjet head. 
     In another embodiment, the ink port adapter further includes a cap configured to cover the supply hose fitting or the return hose fitting. 
     In another embodiment, fastening members are configured to attach the ink port adapter to the inkjet head. 
     In another embodiment, the ink port adapter further includes a plurality of connecting holes through the body to align with threaded holes on one end of the inkjet head, and the fastening members are inserted through the connecting holes of the ink port adapter to screw into the threaded holes on the one end of the inkjet head. 
     In another embodiment, the supply hose fitting connects with a supply reservoir for a single color of ink via a first hose, and the return hose fitting connects with a return reservoir for the single color of ink via a second hose. 
     Another embodiment comprises an apparatus comprising an inkjet head having flow-through ink channels, where each end of the inkjet head includes two inlet ink ports and two outlet ink ports. The apparatus further includes a first ink port adapter and a second ink port adapter. Each of the first ink port adapter and the second ink port adapter comprises a body having a first surface and a second surface, a supply hose fitting that extends from the first surface of the body, a return hose fitting that extends from the first surface of the body, two supply openings on the second surface of the body that align with the two inlet ink ports on one end of the inkjet head, two return openings on the second surface of the body that align with the two outlet ink ports on the one end of the inkjet head, a first ink path through the body that connects the supply hose fitting to the supply openings, a second ink path through the body that connects the return hose fitting to the return openings, and a bypass path that connects between the first ink path and the second ink path. The first ink port adapter is attached to a first end of the inkjet head, and the second ink port adapter is attached to a second end of the inkjet head. 
     In another embodiment, a first cap is attached to the return hose fitting on the first ink port adapter, and a second cap is attached to the supply hose fitting on the second ink port adapter. 
     In another embodiment, a first hose is attached to the supply hose fitting on the first ink port adapter, and is attached to a supply reservoir for a single color of ink. A second hose is attached to the return hose fitting on the second ink port adapter, and is attached to a return reservoir for the single color of ink. 
     In another embodiment, a pressure differential is created between the supply reservoir and the return reservoir. 
     In another embodiment, the bypass path has a higher fluid resistance than the flow-through ink channels of the inkjet head. 
     In another embodiment, the apparatus further includes o-rings compressed between the supply openings and the return openings of the first ink port adapter, and the inlet ink ports and the outlet ink ports on the first end of the two-color inkjet head. The o-rings are seated in recesses in the inlet ink ports and the outlet ink ports on the first end of the inkjet head. 
     Another embodiment comprises an inkjet head having flow-through ink channels, where each end of the inkjet head includes two inlet ink ports and two outlet ink ports. The apparatus further includes a first ink port adapter and a second ink port adapter. Each of the first ink port adapter and the second ink port adapter comprises a body having a first surface and a second surface, a supply hose fitting that extends from the first surface of the body, a return hose fitting that extends from the first surface of the body, two supply openings on the second surface of the body that align with the two inlet ink ports on one end of the inkjet head, two return openings on the second surface of the body that align with the two outlet ink ports on the one end of the inkjet head, a first ink path through the body that connects the supply hose fitting to the supply openings, and a second ink path through the body that connects the return hose fitting to the return openings. The first ink port adapter is attached to a first end of the inkjet head, and the second ink port adapter is attached to a second end of the inkjet head. 
     In another embodiment, a first cap is attached to the return hose fitting on the first ink port adapter, and a second cap is attached to the supply hose fitting on the second ink port adapter. 
     In another embodiment, a first hose is attached to the supply hose fitting on the first ink port adapter, and is attached to a supply reservoir for a single color of ink. A second hose is attached to the return hose fitting on the second ink port adapter, and is attached to a return reservoir for the single color of ink. 
     In another embodiment, a first cap is attached to the return hose fitting on the second ink port adapter, and a second cap is attached to the supply hose fitting on the second ink port adapter. 
     In another embodiment, a first hose is attached to the supply hose fitting on the first ink port adapter, and is attached to a supply reservoir for a single color of ink. A second hose is attached to the return hose fitting on the first ink port adapter, and is attached to a return reservoir for the single color of ink. 
     The above summary provides a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is intended to neither identify key or critical elements of the specification nor delineate any scope particular embodiments of the specification, or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented later. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Some embodiments of the present disclosure are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings. 
         FIG. 1  illustrates an inkjet head. 
         FIG. 2  illustrates an I/O side of an inkjet head in one example. 
         FIG. 3  is a schematic view of an inkjet head. 
         FIG. 4  illustrates an I/O side of an inkjet head in another example. 
         FIG. 5  is a schematic view of an inkjet head. 
         FIG. 6  illustrates one end of an inkjet head in an exemplary embodiment. 
         FIG. 7  is an isometric view of an ink port adapter in an exemplary embodiment. 
         FIGS. 8A-8B  illustrate top and bottom views of an ink port adapter in an exemplary embodiment. 
         FIGS. 9-10  are cross-sectional views of an ink port adapter being attached to an inkjet head in an exemplary embodiment. 
         FIG. 11  is an isometric view of an ink port adapter in an exemplary embodiment. 
         FIGS. 12A-12B  illustrate top and bottom views of an ink port adapter in an exemplary embodiment. 
         FIGS. 13-14  are cross-sectional views of an ink port adapter being attached to an inkjet head in an exemplary embodiment. 
         FIG. 15  illustrates one end of an inkjet head in an exemplary embodiment. 
         FIG. 16  is an isometric view of an ink port adapter in an exemplary embodiment. 
         FIGS. 17A-17B  illustrate top and bottom views of an ink port adapter in an exemplary embodiment. 
         FIG. 18  is a cross-sectional view of an ink port adapter being attached to an inkjet head in an exemplary embodiment. 
         FIG. 19  illustrates an I/O side of an inkjet head in an exemplary embodiment. 
         FIG. 20  is a schematic view of an inkjet head as shown in  FIG. 19  in an exemplary embodiment. 
         FIG. 21  is an isometric view of an ink port adapter in an exemplary embodiment. 
         FIGS. 22A-22B  illustrate top and bottom views of an ink port adapter in an exemplary embodiment. 
         FIG. 23  illustrates ink port adapters installed on each end of an inkjet head in an exemplary embodiment. 
         FIG. 24  is a cross-sectional view of an ink port adapter attached to an inkjet head in an exemplary embodiment. 
         FIG. 25  is a schematic view of an inkjet head with ink port adapters attached in an exemplary embodiment. 
         FIG. 26  is an isometric view of an ink port adapter in an exemplary embodiment. 
         FIGS. 27A-27B  illustrate top and bottom views of an ink port adapter in an exemplary embodiment. 
         FIG. 28  illustrates ink port adapters installed on each end of an inkjet head in an exemplary embodiment. 
         FIG. 29  is a cross-sectional view of an ink port adapter attached to an inkjet head in an exemplary embodiment. 
         FIG. 30  is a schematic view of an inkjet head with ink port adapters attached in an exemplary embodiment. 
         FIG. 31  is a schematic view of an inkjet head with ink port adapters attached in an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The figures and the following description illustrate specific exemplary embodiments. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the embodiments and are included within the scope of the embodiments. Furthermore, any examples described herein are intended to aid in understanding the principles of the embodiments, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the inventive concept(s) is not limited to the specific embodiments or examples described below, but by the claims and their equivalents. 
       FIG. 1  illustrates an inkjet head  100 . Although not visible in  FIG. 1 , inkjet head  100  includes a nozzle surface  102  with one or more rows of nozzles that jet or eject droplets of liquid material, such as ink (e.g., water, solvent, oil, or UV-curable). Opposite the nozzle surface  102  is the side of inkjet head  100  used for input/output (I/O) of ink, electronic signals, etc. This side of inkjet head  100  is referred to as the I/O side  104 . I/O side  104  includes electronics  106  that connect to a data source through cabling  108 . Electronics  106  control how the nozzles of inkjet head  100  jet droplets of ink. As will be described in more detail below, I/O side  104  also includes ink ports for transferring ink into or out of inkjet head  100 . Although the term “ink” is used herein, inkjet head  100  is capable of dispersing different types of liquid material used for printing. 
       FIG. 2  illustrates the I/O side  104  of inkjet head  100  in one example. In the example shown in  FIG. 2 , inkjet head  100  may comprise a four-color head. I/O side  104  has two ends  202 - 203  that are separated by electrical connectors  206 - 207 . Each end  202 - 203  includes four ink ports. For example, end  202  includes ink ports  210 ,  212 ,  214 , and  216 . End  203  includes ink ports  211 ,  213 ,  215 , and  217 . An ink port represents an opening for receiving ink from an ink supply, or transferring ink out of inkjet head  100 . Ink ports  210 - 217  provide a pathway to ink manifolds within inkjet head  100 . An ink manifold is a conduit within an inkjet head for providing ink to a plurality of ink channels/nozzles for jetting.  FIG. 3  is a schematic view of inkjet head  100  as shown in  FIG. 2 . Ink ports  210 - 211  provide pathways to an ink manifold  310 , such as for a first color. Ink ports  212 - 213  provide pathways to an ink manifold  312 , such as for a second color. Ink ports  214 - 215  provide pathways to an ink manifold  314 , such as for a third color. Ink ports  216 - 217  provide pathways to an ink manifold  316 , such as for a fourth color. Each of the ink manifolds  310 - 316  connects to a row of nozzles  320 - 322 , and provides ink to the nozzles  320 - 322  for jetting. 
       FIG. 4  illustrates the I/O side  104  of inkjet head  100  in another example. In the example shown in  FIG. 4 , inkjet head  100  may comprise a two-color head. I/O side  104  has two ends  402 - 403  that are separated by electrical connectors  406 - 407 . Each end  402 - 403  includes two ink ports. For example, end  402  includes ink ports  410  and  412 . End  403  includes ink ports  411  and  413 .  FIG. 5  is a schematic view of inkjet head  100  as shown in  FIG. 4 . Ink ports  410 - 411  provide pathways to ink manifolds  510  and  512 , such as for a first color. Ink ports  412 - 413  provide pathways to ink manifolds  514  and  516 , such as for a second color. Each of the ink manifolds  510 - 516  connects to a row of nozzles  520 - 522 , and provides ink to the nozzles  520 - 522  for jetting. 
     When using inkjet heads as described above, a user may want to reduce the number of colors that are used with an inkjet head. For example, if a user has a four-color inkjet head, he/she may want to operate the four-color inkjet head as a two-color or a single-color inkjet head. If a user has a two-color inkjet head, he/she may want to operate the two-color inkjet head as a single-color inkjet head. To accommodate this, ink port adapters are described herein that allow multi-color inkjet heads to be used with a reduced number of colors. For example, an ink port adapter may convert a four-color inkjet head for use as a two-color or a single-color inkjet head. An ink port adapter may convert a two-color inkjet head for use as a single-color inkjet head. Descriptions of the ink port adapters are described below. 
       FIG. 6  illustrates one end of an inkjet head  600  in an exemplary embodiment. End  602  is separated from the other end (not shown) of inkjet head  600  by electrical connectors  606 - 607 . End  602  includes four ink ports  610 - 613 , which comprise openings for transferring ink to/from inkjet head  600 . Although not visible in  FIG. 6 , each ink port  610 - 613  connects to an ink manifold within inkjet head  600 . In this embodiment, ink ports  610 - 613  may each include a recess  620 - 623  for receiving an o-ring, which is described further below. End  602  also includes threaded holes  630 - 632  for receiving a fastening member, such as a screw or bolt. 
     If inkjet head  600  is a four-color inkjet head, it may be used as a two-color inkjet head with the use of ink port adapters as described herein.  FIG. 7  is an isometric view of an ink port adapter  700  in an exemplary embodiment. Ink port adapter  700  is an apparatus that may convert a four-color inkjet head to a two-color inkjet head. Ink port adapter  700  includes a body  701  having a top surface  702  and a bottom surface  703 . Although the terms “top” and “bottom” are used herein, it is merely to distinguish the surfaces  702 - 703  in  FIG. 7 . The body  701  of ink port adapter  700  may be made from plastic, Teflon®, or any other desired material. Top surface  702  includes hose fittings  710 - 711 , which are hollow cylindrical features that extend from top surface  702  to act as a connection point for a hose, such as from an ink reservoir. A hose is able to slide over each of hose fittings  710 - 711 . Although not shown in  FIG. 7 , hose fittings  710 - 711  may be barbed or have other surface features for securing a hose. Ink port adapter  700  also includes a plurality of connecting holes  720 - 722  that pass from top surface  702  to bottom surface  703  to align with threaded holes  630 - 632  on inkjet head  600 . Fastening members  730 , such as screws or bolts, are inserted through connecting holes  720 - 722 , and screw into threaded holes  630 - 632  to secure ink port adapter  700  to inkjet head  600 . 
       FIGS. 8A-8B  illustrate top and bottom views of ink port adapter  700  in an exemplary embodiment. The top view  801  in  FIG. 8A  illustrates hose fittings  710 - 711  and connecting holes  720 - 722  on top surface  702  of ink port adapter  700 . The bottom view  802  in  FIG. 8B  illustrates four openings  810 - 813  on bottom surface  703  of ink port adapter  700 , and connecting holes  720 - 722 . As is evident from top view  801  and bottom view  802 , connecting holes  720 - 722  pass through the body  701  of ink port adapter  700  from top surface  702  to bottom surface  703 . Openings  810 - 813  are configured to align with the four ink ports  610 - 613  of inkjet head  600  (see  FIG. 6 ). Although not visible in  FIGS. 8A-8B , an ink path passes through body  701  that connects hose fitting  710  to openings  810 - 811 . Another separate ink path passes through body  701  that connects hose fitting  711  to openings  812 - 813 . An ink path is a hollow channel through body  701  that allows ink to flow, such as between a hose fitting  710 - 711  on top surface  702  and multiple openings  810 - 813  on bottom surface  703 . 
       FIGS. 9-10  are cross-sectional views of ink port adapter  700  being attached to inkjet head  600  in an exemplary embodiment.  FIG. 9  is a cross-section substantially along line  9 - 9  of  FIG. 6 , and  FIG. 10  is a cross-section substantially along line  10 - 10  of  FIG. 6 . Ink ports  610 - 613  of inkjet head  600  include recesses  620 - 623 , respectively. O-rings  902  may be inserted into recesses  620 - 623 . When compressed, o-rings  902  provide a seal between ink port adapter  700  and inkjet head  600 . Openings  810 - 813  on ink port adapter  700  align with ink ports  610 - 613  to provide a fluid connection. An ink path  910  connects hose fitting  710  to openings  810 - 811 . Therefore, ink flowing from a hose into hose fitting  710  will travel through adapter  700  to both opening  810  and opening  811 . Another ink path  911  connects hose fitting  711  to openings  812 - 813 . Therefore, ink flowing from a hose into hose fitting  711  will travel through adapter  700  to both opening  812  and opening  813 . 
     When in use, ink port adapter  700  is placed onto end  602  of inkjet head  600 , and is fastened to inkjet head  600  with fastening members  730 . In  FIG. 6 , the other end (not shown) of inkjet head  600  will have a similar configuration with ink ports, and an ink port adapter may be attached to the other end of inkjet head  600  in a similar manner. Hoses are connected to hose fittings  710 - 711 . The hoses may be attached to ink reservoirs of different colors to supply two colors of ink to inkjet head  600 . When one color of ink is supplied through the hose connected to hose fitting  710 , the ink will flow through hose fitting  710 , through ink path  910 , and out openings  810 - 811  into ink ports  610 - 611  of inkjet head  600 . When another color of ink is supplied through the hose connected to hose fitting  711 , the ink will flow through hose fitting  711 , through ink path  911 , and out openings  812 - 813  into ink ports  612 - 613  of inkjet head  600 . Thus, even though inkjet head  600  has four ink ports  610 - 613  on each end able to receive four colors of ink, ink port adapter  700  allows inkjet head  600  to operate while receiving only two colors of ink. 
     Although o-rings  902  are illustrated in  FIGS. 9-10 , other types of sealing mechanisms may be used between ink port adapter  700  and inkjet head  600 . For example, a gasket may be used as a sealing mechanism in another embodiment. When a gasket is used, recesses  620 - 623  may not be needed in ink ports  610 - 613 . 
     If inkjet head  600  (see  FIG. 6 ) is a four-color inkjet head, it may also be used as a single-color inkjet head with the use of other ink port adapters.  FIG. 11  is an isometric view of an ink port adapter  1100  in an exemplary embodiment. Ink port adapter  1100  is an apparatus that may convert a four-color inkjet head to a single-color inkjet head. Ink port adapter  1100  includes a body  1101  having a top surface  1102  and a bottom surface  1103 . Top surface  1102  includes a hose fitting  1110 . Ink port adapter  1100  also includes a plurality of connecting holes  1120 - 1122  that pass from top surface  1102  to bottom surface  1103  to align with threaded holes  630 - 632  on inkjet head  600 . Fastening members  1130  are inserted through connecting holes  1120 - 1122 , and screw into threaded holes  630 - 632  to secure ink port adapter  1100  to inkjet head  600 . 
       FIGS. 12A-12B  illustrate top and bottom views of ink port adapter  1100  in an exemplary embodiment. The top view  1201  in  FIG. 12A  illustrates hose fitting  1110  and connecting holes  1120 - 1122  on top surface  1102  of ink port adapter  1100 . The bottom view  1202  in  FIG. 12B  illustrates four openings  1210 - 1213  on bottom surface  1103  of ink port adapter  1100 , and connecting holes  1120 - 1122 . As is evident from top view  1201  and bottom view  1202 , connecting holes  1120 - 1122  pass through the body  1101  of ink port adapter  1100  from top surface  1102  to bottom surface  1103 . Openings  1210 - 1213  are configured to align with the four ink ports  610 - 613  of inkjet head  600  (see  FIG. 6 ). Although not visible in  FIGS. 12A-12B , an ink path passes through body  1101  that connects hose fitting  1110  to openings  1210 - 1213 . 
       FIGS. 13-14  are cross-sectional views of ink port adapter  1100  being attached to inkjet head  600  in an exemplary embodiment.  FIG. 13  is a cross-section substantially along line  9 - 9  of  FIG. 6 , and  FIG. 14  is a cross-section along substantially line  10 - 10  of  FIG. 6 . Ink ports  610 - 613  of inkjet head  600  include recesses  620 - 623 , respectively. O-rings  902  may be inserted into recesses  620 - 623 . When compressed, o-rings  902  provide a seal between ink port adapter  1100  and inkjet head  600 . Openings  1210 - 1213  on ink port adapter  1100  align with ink ports  610 - 613  to provide a fluid connection. An ink path  1310  connects hose fitting  1110  to openings  1210 - 1213 . Therefore, ink flowing from a hose into hose fitting  1110  will travel through adapter  1100  to each of openings  1210 - 1213 . 
     When in use, ink port adapter  1100  is placed onto end  602  of inkjet head  600 , and is fastened to inkjet head  600  with fastening members  1130 . In  FIG. 6 , the other end (not shown) of inkjet head  600  will have a similar configuration with ink ports, and an ink port adapter may be attached to the other end of inkjet head  600  in a similar manner. A hose is connected to hose fitting  1110 . The hose may be attached to an ink reservoir of a single color to supply one color of ink to inkjet head  600 . When one color of ink is supplied through the hose connected to hose fitting  1110 , the ink will flow through hose fitting  1110 , through ink path  1310 , and out openings  1210 - 1213  into ink ports  610 - 613  of inkjet head  600 . Thus, even though inkjet head  600  has four ink ports on each end for receiving four colors of ink, ink port adapter  1100  allows inkjet head  600  to operate while receiving only one color of ink. 
       FIG. 15  illustrates one end of an inkjet head  1500  in an exemplary embodiment. End  1502  is separated from the other end (not shown) of inkjet head  1500  by electrical connectors  1506 - 1507 . End  1502  includes two ink ports  1510 - 1511 , which comprise openings for transferring ink to/from inkjet head  1500 . Although not visible in  FIG. 15 , each ink port  1510 - 1511  connects to an ink manifold within inkjet head  1500 . In this embodiment, ink ports  1510 - 1511  may each include a recess  1520 - 1521  for receiving an o-ring, which is described further below. End  1502  also includes threaded holes  1530 - 1532  for receiving a fastening member, such as a screw or bolt. 
     If inkjet head  1500  is a two-color inkjet head, it may be used as a single-color inkjet head with the use of ink port adapters.  FIG. 16  is an isometric view of an ink port adapter  1600  in an exemplary embodiment. Ink port adapter  1600  is an apparatus that may convert a two-color inkjet head to a single-color inkjet head. Ink port adapter  1600  includes a body  1601  having a top surface  1602  and a bottom surface  1603 . Top surface  1602  includes a hose fitting  1610 . Ink port adapter  1600  also includes a plurality of connecting holes  1620 - 1622  that pass from top surface  1602  to bottom surface  1603  to align with threaded holes  1530 - 1532  on inkjet head  1500 . Fastening members  1630 , such as screws or bolts, are inserted through connecting holes  1620 - 1622 , and screw into threaded holes  1530 - 1532  to secure ink port adapter  1600  to inkjet head  1500 . 
       FIGS. 17A-17B  illustrate top and bottom views of ink port adapter  1600  in an exemplary embodiment. The top view  1701  in  FIG. 17A  illustrates hose fitting  1610  and connecting holes  1620 - 1622  on top surface  1602  of ink port adapter  1600 . The bottom view  1702  in  FIG. 17B  illustrates two openings  1710 - 1711  on bottom surface  1603  of ink port adapter  1600 , and connecting holes  1620 - 1622 . As is evident from top view  1701  and bottom view  1702 , connecting holes  1620 - 1622  pass through the body  1601  of ink port adapter  1600  from top surface  1602  to bottom surface  1603 . Openings  1710 - 1711  are configured to align with the two ink ports  1510 - 1511  of inkjet head  1500  (see  FIG. 15 ). Although not visible in  FIGS. 17A-17B , an ink path passes through body  1601  that connects hose fitting  1610  to openings  1710 - 1711 . 
       FIG. 18  is a cross-sectional view of ink port adapter  1600  being attached to inkjet head  1500  in an exemplary embodiment.  FIG. 18  is a cross-section substantially along line  18 - 18  of  FIG. 15 . Ink ports  1510 - 1511  of inkjet head  1500  include recesses  1520 - 1521 , respectively. O-rings  902  may be inserted into recesses  1520 - 1521 . When compressed, o-rings  902  provide a seal between ink port adapter  1600  and inkjet head  1500 . Openings  1710 - 1711  on ink port adapter  1600  align with ink ports  1510 - 1511  to provide a fluid connection. An ink path  1810  connects hose fitting  1610  to openings  1710 - 1711 . Therefore, ink flowing from a hose into hose fitting  1610  will travel through adapter  1600  to both opening  1710  and opening  1711 . 
     When in use, ink port adapter  1500  is placed onto end  1502  of inkjet head  1500 , and is fastened to inkjet head  1500  with fastening members  1630 . In  FIG. 15 , the other end (not shown) of inkjet head  1500  will have a similar configuration with ink ports, and an ink port adapter may be attached to the other end of inkjet head  1500  in a similar manner. A hose is connected to hose fitting  1610 . The hose may be attached to an ink reservoir of a single color to supply one color of ink to inkjet head  1500 . When one color of ink is supplied through the hose connected to hose fitting  1610 , the ink will flow through hose fitting  1610 , through ink path  1810 , and out openings  1710 - 1711  into ink ports  1510 - 1511  of inkjet head  1500 . Thus, even though inkjet head  1500  has two ink ports on each end for receiving two colors of ink, ink port adapter  1600  allows inkjet head  1500  to operate while receiving only one color of ink. 
     One type of inkjet head is referred to as a flow-through inkjet head. In a traditional inkjet head that is not a flow-through type, the ink channels typically include a restrictor, a chamber, and a nozzle. The ink enters the chamber through the restrictor, and is contained in the chamber until it is ejected out of the nozzle. A flow-through inkjet head has a structure with a return path out of the ink chamber. For example, an ink channel of a flow-through inkjet head may include another restrictor connected to the chamber that allows ink, which is not ejected out of the nozzle, to flow out of the chamber. Thus, ink may circulate or flow through the ink channels. 
       FIG. 19  illustrates the I/O side  1901  of an inkjet head  1900  in an exemplary embodiment. Inkjet head  1900  is a flow-through head in this embodiment. I/O side  1901  has two ends  1902 - 1903  that are separated by electrical connectors  1906 - 1907 . End  1902  includes four ink ports  1910 - 1913 , and end  1903  includes four ink ports  1914 - 1917 . To provide the flow-through characteristics, inkjet head  1900  has inlet ink ports and outlet ink ports on each end  1902 - 1903 . For example, end  1902  includes inlet ink ports  1910  and  1913 , and outlet ink ports  1911 - 1912 . End  1909  includes inlet ink ports  1914  and  1917 , and outlet ink ports  1915 - 1916 . An inlet ink port comprises a port that allows ink or another print fluid to flow into inkjet head  1900 . An outlet ink port comprises a port that allows ink or another print fluid to flow out of inkjet head  1900 . Although not visible in  FIG. 19 , inlet ink ports  1910 ,  1913 ,  1914 , and  1917  connect to supply manifolds within inkjet head  1900 , and outlet ink ports  1911 - 1912  and  1915 - 1916  connect to return manifolds within inkjet head  1900 . 
     In this embodiment, ink ports  1910 - 1917  may each include a recess  1920 - 1927 , respectively, for receiving an o-ring, which is described further below. End  1902  also includes threaded holes  1930 - 1932  for receiving a fastening member, such as a screw or bolt, and end  1903  includes threaded holes  1933 - 1935 . 
       FIG. 20  is a schematic view of inkjet head  1900  as shown in  FIG. 19  in an exemplary embodiment. Inkjet head  1900  includes a plurality of ink channels  2001  that are aligned into rows. In this embodiment, there are four rows of ink channels  2001 , each having a nozzle  2002 , a chamber (not visible), and a mechanism (not visible) for ejecting a print fluid from the chamber and through the nozzle  2002 . The top two rows of ink channels  2001  in  FIG. 20  may be for a first color and the bottom two rows of ink channels  2001  may be for a second color, although inkjet head  1900  may be used for a single color. In this embodiment, inkjet head  1900  includes supply manifolds and return manifolds. For example, inkjet head  1900  includes supply manifold  2010  and a return manifold  2011  for the top two rows of ink channels  2001 . Supply manifold  2010  acts to supply ink from a supply reservoir to a subset (i.e., one or more rows) of ink channels  2001  of inkjet head  1900 , such as for a first color. Depending on the structure of ink channels  2001  within inkjet head  1900 , the ink will flow from supply manifold  2010 , through first restrictors, and into the chambers. Because of the flow-through nature of inkjet head  1900 , ink (which is not ejected out of nozzles  2002  of ink channels  2001 ) will flow from the chambers, through a second restrictor, and into return manifold  2011 . Return manifold  2011  acts to return ink from the subset of ink channels  2001  to a return reservoir, such as for the first color. Supply manifold  2010  is therefore fluidly connected to return manifold  2011  through ink channels  2001  of inkjet head  1900 . 
     Inlet ink ports  1910  and  1914  provide pathways to supply manifold  2010 . Thus, an ink reservoir may be connected in some manner to inlet ink ports  1910  and  1914  to deliver ink to supply manifold  2010 . Because supply manifold  2010  includes inlets (i.e., inlet ink ports  1910  and  1914 ) at both ends  1902 - 1903  of inkjet head  1900  (see  FIG. 19 ), ink is able to flow to all ink channels  2001  within inkjet head  1900  without dead space. Outlet ink ports  1911  and  1915  provide pathways to return manifold  2011 . Thus, a return reservoir for the first color may be connected in some manner to outlet ink ports  1911  and  1915  to receive ink from return manifold  2011 . 
     Inkjet head  1900  also includes supply manifold  2012  and a return manifold  2013  for the bottom two rows of ink channels  2001 . Supply manifold  2012  acts to supply ink from a supply reservoir to another subset of ink channels  2001  of inkjet head  1900 , such as for a second color. Depending on the structure of ink channels  2001  within inkjet head  1900 , the ink will flow from supply manifold  2012 , through first restrictors, and into the chambers. Because of the flow-through nature of inkjet head  1900 , ink (which is not ejected out of nozzles  2002  of ink channels  2001 ) will flow from the chambers, through a second restrictor, and into return manifold  2013 . Return manifold  2013  acts to return ink from the other subset of ink channels  2001  to a return reservoir, such as for the second color. Supply manifold  2012  is therefore fluidly connected to return manifold  2013  through ink channels  2001  of inkjet head  1900 . 
     Inlet ink ports  1913  and  1917  provide pathways to supply manifold  2012 . Thus, an ink reservoir may be connected in some manner to inlet ink ports  1913  and  1917  to deliver ink to supply manifold  2012 . Because supply manifold  2012  includes inlets (i.e., inlet ink ports  1913  and  1917 ) at both ends  1902 - 1903  of inkjet head  1900  (see  FIG. 19 ), ink is provided to flow to all ink channels  2001  within inkjet head  1900  without dead space. Outlet ink ports  1912  and  1916  provide pathways to return manifold  2013 . Thus, a return reservoir may be connected in some manner to outlet ink ports  1912  and  1916  to receive ink from return manifold  2013 . 
     If inkjet head  1900  is a two-color inkjet head, it may be used as a single-color inkjet head with the use of ink port adapters as described herein.  FIG. 21  is an isometric view of an ink port adapter  2100  in an exemplary embodiment. Ink port adapter  2100  is an apparatus that may convert a two-color inkjet head to a single-color inkjet head, when the two-color inkjet head is a flow-through type. Ink port adapter  2100  includes a body  2101  having a top surface  2102  and a bottom surface  2103 . Although the terms “top” and “bottom” are used herein, it is merely to distinguish the surfaces  2102 - 2103  in  FIG. 21 . The body  2101  of ink port adapter  2100  may be made from plastic, Teflon®, or any other desired material. Top surface  2102  includes a supply hose fitting  2110  and a return hose fitting  2111 , which are each hollow cylindrical features that extend from top surface  2102  to act as a connection point for a hose or gasket. Although not shown in  FIG. 21 , hose fittings  2110 - 2111  may be barbed or have other surface features for securing a hose or otherwise interfacing with a hose or gasket. Ink port adapter  2100  also includes a plurality of connecting holes  2120 - 2122  that pass from top surface  2102  to bottom surface  2103  to align with threaded holes  1930 - 1932  or  1933 - 1935  on inkjet head  1900 . Fastening members  2130 , such as screws or bolts, are inserted through connecting holes  2120 - 2122 , and screw into threaded holes  1930 - 1932  or  1933 - 1935  to secure ink port adapter  2100  to either end  1902 - 1903  of inkjet head  1900 . Ink port adapter  2100  also includes a cap  2150  that is configured to cover supply hose fitting  2110  or return hose fitting  2111  to stop an ink flow as desired. The use of cap  2150  is discussed in further detail below. 
       FIGS. 22A-22B  illustrate top and bottom views of ink port adapter  2100  in an exemplary embodiment. The top view  2201  in  FIG. 22A  illustrates supply hose fitting  2110 , return hose fitting  2111 , and connecting holes  2120 - 2122  on top surface  2102  of ink port adapter  2100 . The bottom view  2202  in  FIG. 22B  illustrates two supply openings  2210  and  2213  on bottom surface  2103  of ink port adapter  2100 , two return openings  2211 - 2212  on bottom surface  2103  of ink port adapter  2100 , and connecting holes  2120 - 2122 . As is evident from top view  2201  and bottom view  2202 , connecting holes  2120 - 2122  pass through the body  2101  of ink port adapter  2100  from top surface  2102  to bottom surface  2103 . Supply openings  2210  and  2213  are configured to align with inlet ink ports (e.g., inlet ink ports  1910  and  1913 ) of inkjet head  1900  (see  FIG. 19 ). Return openings  2211 - 2212  are configured to align with outlet ink ports (e.g., outlet ink ports  1911 - 1912 ) of inkjet head  1900  (see  FIG. 19 ). Although not visible in  FIGS. 22A-22B , an ink path passes through body  2101  that connects supply hose fitting  2110  to supply openings  2210  and  2213 . Another separate ink path passes through body  2101  that connects return hose fitting  2111  to return openings  2211 - 2212 . An ink path is a hollow channel through body  2101  that allows ink to flow. The placement of supply openings  2210  and  2213  and return openings  2211 - 2212  in  FIG. 22B  is just an example, and may change based on the placement of inlet ink ports and outlet ink ports on an inkjet head. 
       FIG. 23  illustrates ink port adapters  2100  installed on each end of inkjet head  1900  in an exemplary embodiment.  FIG. 24  is a cross-sectional view of ink port adapter  2100  attached to inkjet head  1900  in an exemplary embodiment.  FIG. 24  is a cross-section approximately along line  24 - 24  of  FIG. 23 . Inlet ink ports  1910  and  1913  of inkjet head  1900  include recesses  1920  and  1923 , respectively, and outlet ink ports  1911 - 1912  of inkjet head  1900  include recesses  1921 - 1922 , respectively. O-rings  2402  may be inserted into recesses  1920 - 1923 . When compressed, o-rings  2402  provide a seal between ink port adapter  2100  and inkjet head  1900 . Supply openings  2210  and  2213  on ink port adapter  2100  align with inlet ink ports  1910  and  1913  to provide a fluid connection. An ink path  2410  connects supply hose fitting  2110  to supply openings  2210  and  2213 , and represents a supply path in ink port adapter  2100 . Therefore, ink flowing into supply hose fitting  2110  will travel through ink path  2410  to both supply openings  2210  and  2213  to supply ink to inkjet head  1900 . Another ink path  2411  connects return hose fitting  2111  to return openings  2211 - 2212 , and represents a return path in ink port adapter  2100 . Therefore, ink flowing out of inkjet head  1900  and into return openings  2211 - 2212  will travel through ink path  2411  and out of return hose fitting  2111 . 
     Ink port adapter  2100  further includes a bypass path  2440  between ink path  2410  and ink path  2411 . Ink paths  2410  and  2411  are distinct ink paths through body  2101  except for the fluid connection via bypass path  2440 . Bypass path  2440  is a high-impedance passage, which means that the fluid resistance of bypass path  2440  is greater than the fluid resistance of ink channels  2001  within inkjet head  1900 . The length or width of bypass path  2440  may be designed in a desired manner to ensure that the fluid resistance of bypass path  2440  is greater than the fluid resistance of ink channels  2001 . Bypass path  2440  helps reduce the pressure delta required for inkjet head  1900 . If a bypass path were to have low impedance, a high capacity pump would be required. Bypass path  2440  also helps reduce difference in pressure between nozzles  2002  closer to an inlet ink port and nozzles  2002  closer to an outlet ink port. 
       FIG. 25  is a schematic view of inkjet head  1900  with ink port adapters  2100  attached in an exemplary embodiment. As in  FIG. 23 , an ink port adapter  2100  is attached to each end of inkjet head  1900 . When an ink port adapter  2100  is attached to the left side of inkjet head  1900  in  FIG. 25 , supply hose fitting  2110  is fluidly connected to inlet ink ports  1910  and  1913  through ink path  2410 . Return hose fitting  2111  is fluidly connected to outlet ink ports  1911 - 1912  through ink path  2411 . Ink path  2410  is fluidly connected to ink path  2411  through high-impedance bypass path  2440 . 
     When an ink port adapter  2100  is attached to the right side of inkjet head  1900  in  FIG. 25 , supply hose fitting  2110  is fluidly connected to inlet ink ports  1914  and  1917  through ink path  2410 . Return hose fitting  2111  is fluidly connected to outlet ink ports  1915 - 1916  through ink path  2411 . Ink path  2410  is fluidly connected to ink path  2411  through high-impedance bypass path  2440 . 
     To operate the two-color inkjet head  1900  as a single color inkjet head, supply hose fitting  2110  on one end (i.e., the left-hand end) of inkjet head  1900  is connected to a supply reservoir  2502 , such as by a hose  2512 , a gasket, etc. At the same time, return hose fitting  2111  on this same end is covered with cap  2150  so that ink cannot flow into or out of return hose fitting  2111 . On the other end (i.e., the right-hand end) of inkjet head  1900 , return hose fitting  2111  is connected to a return reservoir  2503 , such as by a hose  2513 , a gasket, etc. At the same time, supply hose fitting  2110  on this same end is covered with cap  2150  so that ink cannot flow into or out of supply hose fitting  2110 . When ink port adapters  2100  are connected in the manner schematically shown in  FIG. 25 , one end (i.e., the left-hand end) of inkjet head  1900  acts as the inlet end for a single color of ink, while the other end (i.e., the right-hand end) of inkjet head  1900  acts as the outlet end for the single color of ink. A pressure differential is created between supply reservoir  2502  and return reservoir  2503  so that ink flows through inkjet head  1900  as illustrated by the arrows. 
       FIG. 26  is an isometric view of an ink port adapter  2600  in an exemplary embodiment. Ink port adapter  2600  is similar to ink port adapter  2100 , butdoes not include a bypass path as does ink port adapter  2100 . Ink port adapter  2600  includes a body  2601  having a top surface  2602  and a bottom surface  2603 . Although the terms “top” and “bottom” are used herein, it is merely to distinguish the surfaces  2602 - 2603  in  FIG. 26 . Top surface  2602  includes a supply hose fitting  2610  and a return hose fitting  2611 , which are each hollow cylindrical features that extend from top surface  2602  to act as a connection point for a hose or gasket. Although not shown in  FIG. 26 , hose fittings  2610 - 2611  may be barbed or have other surface features for securing a hose or otherwise interfacing with a hose or gasket. Ink port adapter  2600  also includes a plurality of connecting holes  2620 - 2622  that pass from top surface  2602  to bottom surface  2603  to align with threaded holes  1930 - 1932  or  1933 - 1935  on inkjet head  1900 . Fastening members  2630 , such as screws or bolts, are inserted through connecting holes  2620 - 2622 , and screw into threaded holes  1930 - 1932  or  1933 - 1935  to secure ink port adapter  2600  to either end  1902 - 1903  of inkjet head  1900 . Ink port adapter  2600  also includes one or more caps  2650  that are configured to cover supply hose fitting  2610  or return hose fitting  2611  to stop an ink flow as desired. The use of cap  2650  is discussed in further detail below. 
       FIGS. 27A-27B  illustrate top and bottom views of ink port adapter  2600  in an exemplary embodiment. The top view  2701  in  FIG. 27A  illustrates supply hose fitting  2610 , return hose fitting  2611 , and connecting holes  2620 - 2622  on top surface  2602  of ink port adapter  2600 . The bottom view  2702  in  FIG. 27B  illustrates two supply openings  2710  and  2713  on bottom surface  2603  of ink port adapter  2600 , two return openings  2711 - 2712  on bottom surface  2603  of ink port adapter  2600 , and connecting holes  2620 - 2622 . As is evident from top view  2701  and bottom view  2702 , connecting holes  2620 - 2622  pass through the body  2601  of ink port adapter  2600  from top surface  2602  to bottom surface  2603 . Supply openings  2710  and  2713  are configured to align with inlet ink ports (e.g., inlet ink ports  1910  and  1913 ) of inkjet head  1900  (see  FIG. 19 ). Return openings  2711 - 2712  are configured to align with outlet ink ports (e.g., outlet ink ports  1911 - 1912 ) of inkjet head  1900  (see  FIG. 19 ). Although not visible in  FIGS. 27A-27B , an ink path passes through body  2601  that connects supply hose fitting  2610  to supply openings  2710  and  2713 . Another separate ink path passes through body  2601  that connects return hose fitting  2611  to return openings  2711 - 2712 . The placement of supply openings  2710  and  2713  and return openings  2711 - 2712  in  FIG. 27B  is just an example, and may change based on the placement of inlet ink ports and outlet ink ports on an inkjet head. 
       FIG. 28  illustrates ink port adapters  2600  installed on each end of inkjet head  1900  in an exemplary embodiment.  FIG. 29  is a cross-sectional view of ink port adapter  2600  attached to inkjet head  1900  in an exemplary embodiment.  FIG. 29  is a cross-section approximately along line  29 - 29  of  FIG. 28 . Inlet ink ports  1910  and  1913  of inkjet head  1900  include recesses  1920  and  1923 , respectively, and outlet ink ports  1911 - 1912  of inkjet head  1900  include recesses  1921 - 1922 , respectively. O-rings  2902  may be inserted into recesses  1920 - 1923 . When compressed, o-rings  2902  provide a seal between ink port adapter  2600  and inkjet head  1900 . Supply openings  2710  and  2713  on ink port adapter  2600  align with inlet ink ports  1910  and  1913  to provide a fluid connection. An ink path  2910  connects supply hose fitting  2610  to supply openings  2710  and  2713 , and represents a supply path in ink port adapter  2600 . Therefore, ink flowing into supply hose fitting  2610  will travel through ink path  2910  to both supply openings  2710  and  2713  to supply ink to inkjet head  1900 . Another ink path  2911  connects return hose fitting  2611  to return openings  2711 - 2712 , and represents a return path in ink port adapter  2600 . Therefore, ink flowing out of inkjet head  1900  and into return openings  2711 - 2712  will travel through ink path  2911  and out of return hose fitting  2611 . Ink port adapter  2600  does not include a bypass path between ink path  2910  and ink path  2911  as in the prior embodiment. Thus, ink paths  2910  and  2911  are distinct ink paths through body  2601 . 
       FIG. 30  is a schematic view of inkjet head  1900  with ink port adapters  2600  attached in an exemplary embodiment. As in  FIG. 28 , an ink port adapter  2600  is attached to each end of inkjet head  1900 . When an ink port adapter  2600  is attached to the left side of inkjet head  1900  in  FIG. 30 , supply hose fitting  2610  is fluidly connected to inlet ink ports  1910  and  1913  through ink path  2910 . Return hose fitting  2611  is fluidly connected to outlet ink ports  1911 - 1912  through ink path  2911 . 
     When an ink port adapter  2600  is attached to the right side of inkjet head  1900  in  FIG. 30 , supply hose fitting  2610  is fluidly connected to inlet ink ports  1914  and  1917  through ink path  2910 . Return hose fitting  2611  is fluidly connected to outlet ink ports  1915 - 1916  through ink path  2911 . 
     To operate the two-color inkjet head  1900  as a single color inkjet head, supply hose fitting  2610  on one end (i.e., the left-hand end) of inkjet head  1900  is connected to a supply reservoir  3002 , such as by a hose  3012 , a gasket, etc. Return hose fitting  2611  on this same end is connected to a return reservoir  2503 , such as by a hose  2513 , a gasket, etc. On the other end (i.e., the right-hand end) of inkjet head  1900 , return hose fitting  2611  and supply hose fitting  2610  are both covered with cap  2650 . When ink port adapters  2600  are connected in the manner schematically shown in  FIG. 30 , one end (i.e., the left-hand end) of inkjet head  1900  acts as the inlet end and the outlet for a single color of ink. A pressure differential is created between supply reservoir  3002  and return reservoir  3003  so that ink flows through inkjet head  1900  as illustrated by the arrows. 
       FIG. 31  is a schematic view of inkjet head  1900  with ink port adapters  2600  attached in an exemplary embodiment. As in  FIG. 28 , an ink port adapter  2600  is attached to each end of inkjet head  1900 . When an ink port adapter  2600  is attached to the left side of inkjet head  1900  in  FIG. 31 , supply hose fitting  2610  is fluidly connected to inlet ink ports  1910  and  1913  through ink path  2910 . Return hose fitting  2611  is fluidly connected to outlet ink ports  1911 - 1912  through ink path  2911 . 
     When an ink port adapter  2600  is attached to the right side of inkjet head  1900  in  FIG. 31 , supply hose fitting  2610  is fluidly connected to inlet ink ports  1914  and  1917  through ink path  2910 . Return hose fitting  2611  is fluidly connected to outlet ink ports  1915 - 1916  through ink path  2911 . 
     To operate the two-color inkjet head  1900  as a single color inkjet head, supply hose fitting  2610  on one end (i.e., the left-hand end) of inkjet head  1900  is connected to a supply reservoir  3002 , such as by a hose  3012 , a gasket, etc. At the same time, return hose fitting  2611  on this same end is covered with cap  2650  so that ink cannot flow into or out of return hose fitting  2611 . On the other end (i.e., the right-hand end) of inkjet head  1900 , return hose fitting  2611  is connected to a return reservoir  3003 , such as by a hose  3013 , a gasket, etc. At the same time, supply hose fitting  2610  on this same end is covered with cap  2650  so that ink cannot flow into or out of supply hose fitting  2610 . When ink port adapters  2600  are connected in the manner schematically shown in  FIG. 31 , one end (i.e., the left-hand end) of inkjet head  1900  acts as the inlet end for a single color of ink, while the other end (i.e., the right-hand end) of inkjet head  1900  acts as the outlet end for the single color of ink. A pressure differential is created between supply reservoir  3002  and return reservoir  3003  so that ink flows through inkjet head  1900  as illustrated by the arrows. 
     The ink port adapters described above are able to transform multi-color inkjet heads for use with fewer colors. For example, if an ink port adapter is attached to a four-color inkjet head, then the four-color inkjet head may be used as a two-color or single-color inkjet head. If an ink port adapter is attached to a two-color inkjet head, then the two-color inkjet head may be used as a single-color inkjet head. Therefore, a consumer may not have to buy new inkjet heads for different applications. A consumer may buy a four-color head, and use that four-color head for four-color printing in one application, two-color printing in another application (with an adapter), or single-color printing in yet another application (with an adapter). Use of the ink port adapters described above advantageously gives the consumer flexibility in printing with an individual inkjet head. The ink port adapter described above are able to reduce the number of hoses or other connecting lines that are needed to supply ink to, or draw ink from, an inkjet head, which makes installation less cumbersome. 
     Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. The scope of the invention is defined by the following claims and any equivalents thereof.