Patent Publication Number: US-2006001711-A1

Title: Inkjet printhead with multiple ink reservoirs

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This patent application claims the benefit of priority from U.S. provisional patent application No. 60/584,469 filed on Jun. 30, 2004 and entitled “Inkjet Printhead With Multiple Ink Reservoirs” the entire contents of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      Some inkjet printheads include a housing having one to three ink reservoirs which contain ink and supply ink to one or more chips. Inkjet printheads having one ink reservoir typically contain black or mono ink, whereas inkjet printheads having three ink reservoirs typically contain full or half-tone colors of magenta, cyan and yellow. Printers capable of printing in black-and-white and color are usually adapted to hold two printheads, one for black or mono ink, and one for color ink. Other printers are adapted to hold three printheads: one for black or mono ink, one for full-color ink, and one for half-tone color ink. In such printers, three printheads are normally required to obtain seven different ink colors or tones.  
      The greater the number of ink reservoirs in a printhead, the more difficult it becomes to plumb vias for the various inks to one chip. In some cases, inkjet printheads are provided with large and/or multiple chips in order to address this difficulty. However, this significantly increases the expense of the printhead.  
     SUMMARY OF THE INVENTION  
      Some embodiments of the present invention provide an inkjet printhead comprising a housing; a first ink reservoir located in the housing; a second ink reservoir located in the housing, the second ink reservoir separated from the first ink reservoir by a first wall; a third ink reservoir located in the housing and separated from both the first ink reservoir and the second ink reservoir by a second wall, wherein the first wall lies in a plane intersecting the second wall; and a fourth ink reservoir located in the housing and positioned adjacent the third ink reservoir opposite the first ink reservoir and the second ink reservoir.  
      In some embodiments of the present invention, an inkjet printhead is provided, and comprises a housing; an outer surface of the housing adapted to be covered by a chip; a first ink reservoir located in the housing; a second ink reservoir located in the housing and separated from the first ink reservoir by a first wall; a first ink via positioned to fluidly couple the first ink reservoir to the outer surface, the first ink via having a first end opening into the first ink reservoir and a second end opening to the outer surface; a second ink via positioned to fluidly couple the second ink reservoir to the outer surface, the second ink via having a first end opening into the second ink reservoir and a second end opening to the outer surface, the printhead having an orientation in which the outer surface lies in a substantially horizontal plane and in which the first end of the first ink via and the first end of the second ink via are positioned over the outer surface.  
      Some embodiments of the present invention provide an inkjet printhead comprising a housing; a first ink reservoir located in the housing; a second ink reservoir located in the housing, the first ink reservoir separated from the second ink reservoir by a first wall; a third ink reservoir located in the housing and separated from both the first ink reservoir and the second ink reservoir by a second wall, wherein the first wall lies in a plane intersecting the second wall; and a fourth ink reservoir located in the housing and separated from the first ink reservoir and the third ink reservoir by a third wall, wherein the second wall lies in a plane intersecting the third wall.  
      In some embodiments of the present invention, an inkjet printhead is provided, and comprises a housing; an outer surface of the housing adapted to be covered by a chip, the printhead having an orientation in which the outer surface lies in a substantially horizontal plane; at least four ink reservoirs defined in the housing, each of the at least four reservoirs at least partially defined by an inner wall; and an intersection of each of the inner walls, wherein the intersection is located over the outer surface in the orientation of the printhead.  
      Some embodiments of the present invention provide an inkjet printhead comprising: a housing; an outer surface of the housing adapted to be covered by one chip; and at least four ink reservoirs located in the housing, each of the at least four ink reservoirs in fluid communication with the chip for supply of ink from the at least four ink reservoirs to the chip.  
      Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  illustrates an perspective view of an embodiment of an inkjet printhead of the present invention.  
       FIG. 2  illustrates a top view of the inkjet printhead of  FIG. 1 .  
       FIG. 3  illustrates a cross-sectional perspective view of the inkjet printhead of  FIGS. 1-2 , taken along line  3 - 3  of  FIG. 2 , with filters shown.  
       FIG. 4  illustrates a detail cross-sectional perspective view of the inkjet printhead shown in  FIG. 3 .  
       FIG. 5  illustrates a bottom view of the inkjet printhead of  FIGS. 1-4 .  
       FIG. 6  illustrates a top view of another embodiment of an inkjet printhead of the present invention.  
       FIG. 7  illustrates a top view of another embodiment of the inkjet printhead of the present invention.  
       FIG. 8  illustrates a cross-sectional perspective view of the inkjet printhead of  FIG. 7 , taken along line  8 - 8  of  FIG. 7 .  
       FIG. 9  illustrates a detail cross-sectional perspective view of the inkjet printhead shown in  FIG. 8 .  
       FIG. 10  illustrates a bottom view of the inkjet printhead of  FIGS. 7-9 .  
       FIG. 11  illustrates a top view of another embodiment of the inkjet printhead of the present invention.  
       FIG. 12  illustrates a cross-sectional perspective view of the inkjet printhead of  FIG. 11 , taken along line  12 - 12  of  FIG. 11 .  
       FIG. 13  illustrates a detail cross-sectional perspective view of the inkjet printhead shown in  FIG. 12 .  
       FIG. 14  illustrates a bottom view of the inkjet printhead of  FIGS. 11-13 .  
       FIG. 15  illustrates a top view of another embodiment of the inkjet printhead of the present invention. 
    
    
      Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. The use of “including,” “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “mounted,” “connected” and “coupled” are used broadly and encompass both direct and indirect mounting, connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.  
      Further aspects of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the drawings.  
     DETAILED DESCRIPTION  
      The present invention generally relates to a printhead comprising a housing and four or more ink reservoirs located in the housing. Each of the ink reservoirs is in fluid communication with an outer surface of the printhead, such that ink can be directed from each ink reservoir to a printing medium.  
      As used herein and in the appended claims, the term “ink” can refer to at least one of inks, dyes, stains, pigments, colorants, tints, a combination thereof, and any other material that can be used by inkjet printers to print matter upon a printing medium.  
      As used herein and in the appended claims, the term “printing medium” can refer to at least one of paper (including without limitation stock paper, stationary, tissue paper, homemade paper, and the like), film, tape, photo paper, a combination thereof, and any other medium upon which material can be printed by an inkjet printer.  
       FIGS. 1-5  illustrate an inkjet printhead  10  according to an embodiment of the present invention. As shown in  FIG. 1 , the printhead  10  includes a housing  12  that defines a nosepiece  11  and four ink reservoirs  14 ,  16 ,  20 ,  24 . In other embodiments, the housing  12  can have other shapes, some of which have no identifiable nosepiece. Each ink reservoir  14 ,  16 ,  20  and  24  contains ink, such as a quantity of ink filled within the reservoir  14 ,  16 ,  20 ,  24 , and a foam insert saturated with ink. The housing  12  can be constructed of a variety of materials including, without limitation, at least one of polymers, metals, ceramics, composites, and the like.  
      As shown in  FIG. 4 , in some embodiments a chip  13  is coupled to the nosepiece  11  such that it covers an outer surface  17  (see  FIGS. 3-5 ) of the nosepiece  11  and is in fluid communication with one or more of the four ink reservoirs  14 ,  16 ,  20 ,  24 . As used herein and in the appended claims, the term “chip” can refer to one or more layers of material having one or more arrays of heat transducers, firing chambers and/or nozzles (not shown), at least one of the one or more layers being in fluid communication with one or more of the four ink reservoirs  14 ,  16 ,  20 ,  24 . In some embodiments, such as that shown in  FIGS. 1-5 , the chip  13  can be coupled to the printhead  10  such that each of the ink reservoirs  14 ,  16 ,  20 ,  24  is in fluid communication with a respective set of heat transducers, firing chambers, and/or nozzle arrays  33  (see  FIG. 4 ) in the chip  13 . Due to the small size of the individual nozzles in the illustrated embodiment of  FIGS. 1-5 , the nozzle arrays  33  are represented by dashed lines in  FIG. 4 .  
      In some embodiments, ink is directed along a path from an ink reservoir  14 ,  16 ,  20  or  24  toward the outer surface  17  (and the chip  13 , when the chip  13  is coupled to the outer surface  17 ), such that the ink enters one or more firing chambers, and is eventually fired from corresponding nozzles. Ink located in a firing chamber can be heated and vaporized by signaling a corresponding heat transducer to heat up the ink in the firing chamber. The ink can then be expelled outwardly from the printhead  10  through a corresponding nozzle toward a printing medium. In some embodiments, the chip  13  is in electrical communication with a printer controller that controls when various nozzles of the chip  13  fire ink toward a printing medium.  
      The inkjet printhead  10  in the illustrated embodiment of  FIGS. 1-5  comprises four ink reservoirs  14 ,  16 ,  20 ,  24  located in the housing  12 : a first ink reservoir  14 , a second ink reservoir  16  separated from the first ink reservoir  14  by a first wall  18 , a third ink reservoir  20  separated from both the first ink reservoir  14  and the second ink reservoir  16  by a second wall  22  that intersects the first wall  18 , and a fourth ink reservoir  24  separated from the third ink reservoir  20  by a third wall  26 . In this embodiment, the fourth ink reservoir  24  is positioned adjacent the third ink reservoir  20  opposite the first and second ink reservoirs  14 ,  16 . Also in this embodiment, the third and fourth ink reservoirs  20 ,  24  are positioned generally above the nosepiece  11  of the housing  12 , and specifically, over the outer surface  17  of the nosepiece  11  (and the chip  13 , when the chip  13  is coupled to the printhead  10 ).  
      Each of the four ink reservoirs  14 ,  16 ,  20 ,  24  shown in  FIG. 1  has a generally rectangular shape, with a length and a width smaller than the length (with reference to dimensions of the reservoirs  14 ,  16 ,  20 ,  24  viewed from above the housing  12  as shown in  FIG. 2 ). The first and second ink reservoirs  14 ,  16  shown in  FIG. 1  are oriented such that the length of the first ink reservoir  14  is substantially parallel with the length of the second ink reservoir  16 . In addition, the third and fourth ink reservoirs  20 ,  24  shown in  FIG. 1  are oriented such that the length of the third ink reservoir  20  is substantially parallel to the length of the fourth ink reservoir  24 . Furthermore, the lengths of the first and second ink reservoirs  14 ,  16  in  FIG. 1  are oriented substantially perpendicular to the lengths of the third and fourth ink reservoirs  20 ,  24 . The third wall  26  separating the third ink reservoir  20  from the fourth ink reservoir  24  in the embodiment of  FIGS. 1-5  is substantially parallel with the second wall  22 . Accordingly, the first wall  18  that separates the first ink reservoir  14  from the second ink reservoir  16  is oriented substantially perpendicular to the second wall  22  and the third wall  26 .  
      The housing  12  in the embodiment of  FIGS. 1-5  is generally rectangular, and has a length and a width smaller than the length. In some embodiments, the lengths of the first and second ink reservoirs  14 ,  16  are substantially parallel with the length of the housing  12 , and the lengths of the third and fourth ink reservoirs  20  and  24  are substantially parallel with the width of the housing  12 . Other shapes of the housing  12  and ink reservoirs  14 ,  16 ,  20 ,  24  are possible, and fall within the spirit and scope of the present invention.  
      With continued reference to the embodiment of the inkjet printhead  10  illustrated in  FIGS. 1-5 , in some embodiments, the length of the first ink reservoir  14  is approximately equal to that of the second ink reservoir  16 , and the length of the third ink reservoir  20  is approximately equal to that of the fourth ink reservoir  24 . Also, in some embodiments, the length of the third ink reservoir  20  (or the length of the fourth ink reservoir  24 ) is approximately equal to the sum of the widths of the first and second ink reservoirs  14 ,  16 . In such embodiments, if the widths of the first and second ink reservoirs  14 ,  16  are the same, the length of the third ink reservoir  20  (or the fourth ink reservoir  24 ) can be approximately equal to twice the width of the first ink reservoir  14  (or the second ink reservoir  16 ).  
      In some embodiments, the sum of the width of the third ink reservoir  20 , the width of the fourth ink reservoir  24 , and the length of the second ink reservoir  16  (or the first ink reservoir  14 ) is approximately equal to the length of the housing  12 . In addition, in some embodiments the sum of the widths of the first and second ink reservoirs  14 ,  16  is approximately equal to the width of the housing  12 , and the length of the third ink reservoir  20  (or the fourth ink reservoir  24 ) is approximately equal to the width of the housing  12 . It should be noted, however, that the housing  12  has an outer wall  15  that has a thickness, thereby creating an inner and outer length and an inner and outer width of the housing  12 . Therefore, as used herein and in the appended claims, the “length” of the housing  12  and the “width” of the housing  12  generally refers to the inner length and the inner width of the housing  12 .  
      Each of the four ink reservoirs  14 ,  16 ,  20 ,  24  in the illustrated embodiment has an upper portion  30  and a lower portion  32 , as shown in  FIG. 3 . As shown in  FIGS. 2-4 , each of the four ink reservoirs  14 ,  16 ,  20 ,  24  also includes a filter tower  44 ,  54 ,  64 ,  74  positioned adjacent the lower portion  32  to which a filter  42  can be coupled (see, for example, see  FIGS. 3 and 4 ). It should be noted that a variety of types of filters  42  can be used in conjunction with the present invention. For example, the filters  42  illustrated in  FIGS. 3 and 4  are woven filters with a relatively fine mesh size. In other embodiments, no filters  42  are used.  
      A filter  42  can be coupled to each filter tower  44 ,  54 ,  64 ,  74  in any of a variety of manners known in the art (e.g., laser welding, heat staking, etc.). Each filter tower  44 ,  54 ,  64 ,  74  is positioned such that the filter  42  contacts the ink, foam insert, or other ink-carrying element located within the respective ink reservoir  14 ,  16 ,  20  or  24 . In some embodiments, the dimensions of each of the four ink reservoirs  14 ,  16 ,  20 ,  24  is at least partially determined by the accessibility needed to couple each filter  42  to its respective filter tower  44 ,  54 ,  64 ,  74 . For example, the width of each of the four ink reservoirs  14 ,  16 ,  20 ,  24  can be at least partially determined by the size of a heat staking tool used to heat stake a filter  42  to an upper portion of each of the filter towers  44 ,  54 ,  64 ,  74 . The filter towers  44 ,  54 ,  64 ,  74  shown in  FIGS. 2-4  have a generally rectangular shape with rounded corners, although filter towers  4 ,  54 ,  64 ,  74  having any other shape can be used as desired.  
      The ink reservoirs  14 ,  16 ,  20 ,  24  and the filter towers  44 ,  54 ,  64 ,  74  (if used) are sized and shaped to control the rate of ink flow from the ink reservoirs  14 ,  16 ,  20 ,  24  toward the outer surface  17  (and the chip  13 , when the chip  13  is coupled to the printhead  10 ). As shown in  FIG. 2 , the first ink reservoir  14  is the largest reservoir (having a width greater than that of the second ink reservoir  16 ). Also, the filter tower  44  of the first ink reservoir  14  is the largest. Accordingly, the first ink reservoir  14  can be used to contain black or mono ink, and the second ink reservoir  16 , third ink reservoir  20  and fourth ink reservoir  24  can be used to hold a different color of ink (e.g., full-tone or half-tone magenta, full-tone or half-tone cyan, full-tone or half-tone yellow, black, white or gray, and the like). In some embodiments, all four ink reservoirs  14 ,  16 ,  20 ,  24  can have the same volume and be adapted to contain the same volume of ink. Also, in some embodiments, all four ink reservoirs  14 ,  16 ,  20 ,  24  can have the same volume, and the filter towers  44 ,  54 ,  64 ,  74  can be of the same size, such that each of the four ink reservoirs  14 ,  16 ,  20 ,  24  contains the same volume of ink and has the same flow rate of ink toward the outer surface  17 . In still other embodiments, the ink reservoirs  14 ,  16 ,  20 ,  24  can have any other combination of relative volumes and can have filter towers  44 ,  54 ,  64 ,  74  in any combination of relative sizes desired.  
      The ink can flow from each of the four ink reservoirs  14 ,  16 ,  20 ,  24  toward the outer surface  17  (and the chip  13 , when the chip  13  is coupled to the printhead  10 ) along one or more ink vias  46 ,  56 ,  66 ,  76  associated with each reservoir  14 ,  16 ,  20  or  24 . As shown in  FIGS. 2-4 , the first ink reservoir  14  is in fluid communication with a filter  42 , a first filter tower  44  and a first ink via  46  (shown in  FIG. 2  in dotted lines). The first ink via  46  has a first end  48  (see  FIG. 4 ) that opens into a bottom portion of the first filter tower  44  and a second end  50  (see  FIGS. 4-5 ) that opens to the outer surface  17  (and the chip  13 , when the chip  13  is coupled to the outer surface  17 ). In some embodiments, the first end  48  of the first ink via  46  has a cross-sectional area smaller than that of the first filter tower  44 , such that the first end  48  opens into a volume within the first ink reservoir  14  that is surrounded by the first filter tower  44 . Also, in some embodiments, a portion of the first ink via  46  traverses the second wall  22  to reach the second end  50  that opens to the outer surface  17 , and a portion of the first ink via  46  traverses the third wall  26  to reach the second end  50  (the first ink via  46  is truncated in  FIG. 4  for purposes of showing other portions of the printhead  10 , but continues to extend past the third wall  26  as best shown in  FIG. 2 ).  
      As shown in  FIG. 2 , the second ink reservoir  16  is in fluid communication with a filter  42 , a second filter tower  54  and a second ink via  56 . The second ink via  56  has a first end  58  (see  FIG. 2 ) that opens into a bottom portion of the second filter tower  54  and a second end  60  (see  FIG. 5 ) that opens to the outer surface  17  (and the chip  13 , when the chip  13  is coupled to the outer surface  17 ). In some embodiments, the first end  58  of the second ink via  56  has a cross-sectional area smaller than that of the second filter tower  54  such that the first end  58  opens into a volume within the second ink reservoir  16  that is surrounded by the second filter tower  44 . Also, in some embodiments, a portion of the second ink via  56  traverses the second wall  22  to reach the second end  60  that opens to the outer surface  17 , and a portion of the second ink via  56  traverses the third wall  26  to reach the second end  60 .  
      As shown in  FIGS. 2-4 , the third and fourth ink reservoirs  20 ,  24  are in fluid communication with third and fourth filters  42 , third and fourth filter towers  64 ,  74  and third and fourth ink vias  66 ,  76 , respectively. The third and fourth ink vias  66 ,  76  each have a first end  68 ,  78  (see  FIG. 4 ), respectively, that opens into a bottom portion of the third and fourth filter towers  64 ,  74 , respectively, and a second end  70 ,  80  (see  FIGS. 4-5 ) that opens to the outer surface  17  (see  FIG. 4 ). In some embodiments, the first ends  68 ,  78  of the third and fourth ink vias  66 ,  76  have cross-sectional areas smaller than that of the third and fourth filter towers  64 ,  74 , respectively, such that the first ends  68 ,  78  open into a volume within the third and fourth ink reservoirs  20 ,  24  that is surrounded by the third and fourth filter towers  64 ,  74 , respectively.  
      When the printhead  10  illustrated in  FIGS. 1-5  is oriented such that the outer surface  17  lies in a substantially horizontal plane and in which the nosepiece  11  is pointed in a downward direction as shown in  FIG. 1 , at least a portion of each of the first ends  68 ,  78  of the third and fourth ink vias  66 ,  76  is located over the outer surface  17 , such that the third and fourth ink vias  66 ,  76  are substantially vertical. In other words, when the printhead  10  is oriented such that the outer surface  17  lies in a substantially horizontal plane and in which the nozzle  11  is pointed in a downward direction, at least a portion of each of the first ends  68 ,  78  of the third and fourth ink vias  66 ,  76  is positioned substantially directly over the second end  70 ,  80  of the third and fourth ink vias  66 ,  76 , respectively. It should be noted that the third and fourth ink vias  66 ,  76  can have other portions (e.g., branches, extensions, and the like) extending in other directions. However, in some embodiments, at least a portion of these vias  66 ,  76  is substantially vertical and provides an unobstructed straight path from the first ends  68 ,  78  of the vias  66 ,  76  to the outer surface  17  (and the chip  13 , when the chip  13  is coupled to the outer surface  17 ).  
      It should be noted that the printhead  10  (as well as the printheads  100 ,  200 ,  300 ,  400  described below) can have any orientation. Some orientations of the printhead  10  or components of the printhead  10  (e.g., the outer surface  17 ) are identified herein and in the appended claims by reference to a substantially horizontal plane in which an element or feature of the printhead  10  lies. Also, some orientations of the printhead  10  or components of the printhead  10  (e.g., the third and fourth ink vias  66 ,  76 ), are identified herein and in the appended claims as being substantially vertical. Such orientations are referenced only to describe relative positions and orientations of features and elements of the printhead  10  rather than to indicate or imply that the printhead  10  must have any particular orientation in use.  
      Each of the four ink reservoirs  14 ,  16 ,  20 ,  24  illustrated in  FIGS. 1-5  is in fluid communication with the outer surface  17 , and with the chip  13 , when the chip  13  is coupled to the outer surface  17 . As a result, when the chip  13  is coupled to the outer surface  17 , each of the four ink reservoirs  14 ,  16 ,  20 ,  24  is in fluid communication with one of the four nozzle arrays  32 .  
       FIG. 6  illustrates a printhead  100  according to another embodiment of the present invention. The inkjet printhead  100  comprises four ink reservoirs  114 ,  116 ,  120 ,  124  located in a housing  112 : a first ink reservoir  114 , a second ink reservoir  116  separated from the first ink reservoir  114  by a first wall  118 , a third ink reservoir  120  separated from the second ink reservoir  116  by a second wall  122  that is substantially parallel to the first wall  118 , and a fourth ink reservoir  124  separated from the third ink reservoir  120  by a third wall  126  that is substantially parallel to the first and second walls  118 ,  122 . The fourth ink reservoir  124  is positioned adjacent the third ink reservoir  120  opposite the second ink reservoir  116 . The third and fourth ink reservoirs  120 ,  124  are positioned generally above a nosepiece  111  of the housing  112  (similar to the printhead  10  illustrated in  FIGS. 1-5 ), and specifically, over the outer surface  117  adapted to be covered by a chip (and a chip, when a chip is coupled to the outer surface  117 ).  
      The printhead  100  illustrated in  FIG. 6  includes many of the features of the printhead  10  illustrated in  FIGS. 1-5 . One difference between the printheads  10 ,  100  is that the third wall  126  of the housing  112  does not intersect the second wall  122 . Also, the ink via  146  running from the first ink reservoir  114  toward the outer surface  117  runs beneath a portion of the second ink reservoir  116 . Each of the four ink reservoirs  114 ,  116 ,  120 ,  124  is in fluid communication with the outer surface  117  of the housing  112  in a manner similar to that described above with respect to the printhead  10  illustrated in  FIGS. 1-5 . That is, for example, each of the ink reservoirs  114 ,  116 ,  120 ,  124  is in fluid communication with a respective filter tower  144 ,  154 ,  164 ,  174  and a respective ink via  146 ,  156 ,  166 ,  176  following a respective path toward the outer surface  117  of the printhead  110 .  
       FIGS. 7-10  illustrate a printhead  200  according to another embodiment of the present invention. The printhead  200  comprises a housing  212  that defines a nosepiece  211  and four ink reservoirs  214 ,  216 ,  220 ,  224 : a first ink reservoir  214 , a second ink reservoir  216  separated from the first ink reservoir  214  by a first wall  218 , a third ink reservoir  220  separated from both the first ink reservoir  214  and the second ink reservoir  216  by a second wall  222  that intersects the first wall  218 , and a fourth ink reservoir  224  separated from the first ink reservoir  214  and the third ink reservoir  220  by a third wall  226  that intersects the second wall  222 . In other embodiments, the housing  212  can have other shapes, some of which have no identifiable nosepiece. In the embodiment of the present invention shown in  FIGS. 7 and 8 , the first wall  218  is substantially parallel to the third wall  226 , and the second wall  222  is substantially orthogonal to the first wall  218  and the third wall  226 . It should be noted; however, that the first, second and third walls  218 ,  222  and  226  need not necessarily be oriented in this manner. For example, the walls  218 ,  222 , and  226  can be configured in other manners in which the first wall  218  lies in a plane that intersects the second wall  222  and in which the second wall  222  lies in a plane that intersects the third wall  226 .  
      Each of the four ink reservoirs  214 ,  216 ,  220 ,  224  illustrated in  FIGS. 7-10  is generally rectangular. In some embodiments, the reservoirs  214 ,  216 ,  220 ,  224  each have a length and width shorter than the length. With reference to the embodiment illustrated in  FIGS. 7-10 , the lengths of the first, second and fourth ink reservoirs  214 ,  216  and  224  are all substantially parallel, and the length of the third ink reservoir  220  is oriented substantially orthogonally with respect to the first, second and fourth ink reservoirs  214 ,  216  and  224 . In addition, the lengths of the first and second ink reservoirs  214 ,  216  in the embodiment of  FIGS. 7-10  are substantially equal, whereas the length of the fourth ink reservoir  224  is greater than the lengths of the first and second ink reservoirs  214 ,  216 . In some embodiments, the length of the fourth ink reservoir  224  is approximately equal to the sum of the length of the first ink reservoir  214  (or the second ink reservoir  216 ) and the width of the third ink reservoir  220  as best shown in  FIG. 7 .  
      In some embodiments, the length of the third ink reservoir  220  is less than the lengths of the first and second ink reservoirs  214 ,  216 , and can be equal to the sum of the widths of the first and second ink reservoirs  214 ,  216 . The first and second ink reservoirs  214 ,  216  can have approximately the same width. In such embodiments, the length of the third ink reservoir  220  can be equal to approximately twice the width of the first ink reservoir  214  (or the second ink reservoir  216 ).  
      The width of the third ink reservoir  220  can be greater than the width of the first ink reservoir  214  and/or the width of the second ink reservoir  216 . Also, in some embodiments, the volume of the first ink reservoir  214  is equal to the volume of the second ink reservoir  216  and/or the volume of the third ink reservoir  220 . Generally, the volume of the fourth ink reservoir  224  can be greater than that of any of the first, second and third ink reservoirs  214 ,  216  and  220 , as shown in  FIGS. 7-10 . As a result, the fourth ink reservoir  224  can contain mono or black ink, and the first, second and third ink reservoirs  214 ,  216  and  220  can contain other colors of ink, as described above.  
      In addition, the housing  212  can be generally rectangular in shape, and can have a length and a width smaller than the length. In the illustrated embodiment of  FIGS. 7-10 , the length of the fourth ink reservoir  224  is approximately equal to the length of the housing  212 . Also in this embodiment, the sum of the length of the third ink reservoir  220  and the width of the fourth ink reservoir  224  is approximately equal to the width of the housing  212 . In other words, the sum of the widths of the first, second and fourth ink reservoirs  214 ,  216  and  224  is approximately equal to the width of the housing  212 . In the embodiment illustrated in  FIGS. 7-10 , the width of the first ink reservoir  214  is approximately equal to the width of the second ink reservoir  216  and the width of the fourth ink reservoir  224 . As a result, the width of the housing  212  is approximately equal to three times the width of the first ink reservoir  214  (or the width of the second ink reservoir  216 , or the width of the fourth ink reservoir  224 ).  
      As with the other embodiments of the present invention, each ink reservoir  214 ,  216 ,  220 ,  224  in the embodiment of  FIGS. 7-10  need not necessarily have a uniform height, length or width along the respective dimensions of the ink reservoir  214 ,  216 ,  220 ,  224 . For example, the third ink reservoir  220  includes a step  221 , such that the third ink reservoir  220  is shallower in depth (i.e., at the step  221 ) in one portion than the other. Specifically, the depth of the third ink reservoir  220  is greater adjacent a third filter tower  264  of the third ink reservoir  220 .  
      As shown in hidden lines in  FIG. 7  and in  FIG. 10 , the housing  212  has an outer surface  217  adapted to be covered by a chip (see, for example, the chip  13  illustrated in the embodiment of  FIGS. 1-5 ). The third ink reservoir  220  in the embodiment of  FIGS. 7-10  is positioned substantially over the outer surface  217  when the printhead  100  is in an orientation in which the outer surface  217  lies in a substantially horizontal plane and the nozzle  211  is pointed in a substantially downward direction. In other words, when the outer surface  217  is positioned substantially horizontally as just described, the outer surface  217  lies below the third ink reservoir  220 .  
      Each of the four ink reservoirs  214 ,  216 ,  220 ,  224  has an upper portion  230  and a lower portion  232 , as best shown in  FIG. 8 . As shown in  FIGS. 7-9 , each of the four ink reservoirs  214 ,  216 ,  220 ,  224  includes a filter tower  244 ,  254 ,  264 ,  274  positioned adjacent the lower portion  232  to which a filter (not shown) can be coupled. The filter can take any form and can be coupled in any manner as described above with reference to the embodiment of  FIGS. 1-5 .  
      As shown in  FIG. 7 , the first ink reservoir  214  is in fluid communication with a first filter tower  244  and a first ink via  246  (shown in dotted lines in  FIG. 7 ). The first ink via  246  has a first end  248  that opens into a bottom portion of the first filter tower  244  and a second end  250  that opens to the outer surface  217  (and a chip, when a chip is coupled to the printhead  200 ). In some embodiments, the first end  248  of the first ink via  246  has a cross-sectional area smaller than that of the first filter tower  244  such that the first end  248  opens into a volume within the first ink reservoir  214  that is surrounded by the first filter tower  244 . Also, in some embodiments, the first ink via  246  traverses the second wall  222  to reach the second end  250  that opens to the outer surface  217 .  
      As further shown in  FIG. 7 , the second ink reservoir  216  is in fluid communication with a second filter tower  254  and a second ink via  256 . The second ink via  256  (which can be similar to the first ink via  246 ) has a first end  258  that opens into a bottom portion of the second filter tower  254  and a second end  260  that opens to the outer surface  217 . In some embodiments, the second ink via  256  traverses the first wall  218  and/or the second wall  222  to reach the second end  250  that opens to the outer surface  217 .  
      As shown in  FIGS. 7-9 , the third ink reservoir  220  is in fluid communication with the third filter tower  264  and a third ink via  266 . The third ink via  266  has a first end  268  that opens into a bottom portion of the third filter tower  264  and a second end  270  that opens to the outer surface  217 . When the printhead  200  illustrated in  FIGS. 7-10  is oriented such that the outer surface  217  lies in a substantially horizontal plane and the nozzle  211  is pointed in a substantially downward direction, the first end  268  of the third ink via  266  is located over the outer surface  217 , such that the third ink via  266  is substantially vertical. In other words, when the printhead  200  is oriented such that the outer surface  217  lies in a substantially horizontal plane as just described, the first end  268  of the third ink via  266  is positioned substantially directly over the second end  270 . It should be noted that the third ink via  266  can have other portions (e.g., branches, extensions, and the like) extending in other directions. However, in some embodiments, at least a portion of the third ink via  266  is substantially vertical and provides an unobstructed straight path from the first end  268  of the third ink via  266  to the outer surface  217  (and a chip, when the chip is coupled to the outer surface  217 ).  
      With continued reference to the embodiment of  FIGS. 7-10 , the fourth ink reservoir  224  is in fluid communication with a fourth filter tower  274  and a fourth ink via  276 . The fourth ink via  276  has a first end  278  and second end  280  similar to those described above. In some embodiments, the fourth ink via  276  traverses the third wall  226  to reach the outer surface  217 .  
       FIGS. 11-14  illustrate a printhead  300  according to another embodiment of the present invention. The printhead  300  comprises a housing  312  that defines a nosepiece  311 . However, in other embodiments, the housing  212  can have other shapes, some of which have no identifiable nosepiece. The printhead  300  illustrated in  FIGS. 11-14  has four ink reservoirs  314 ,  316 ,  320 ,  324 : a first ink reservoir  314 , a second ink reservoir  316  separated from the first ink reservoir  314  by a first wall  318 , a third ink reservoir  320  separated from the second ink reservoir  316  by a second wall  322 , and a fourth ink reservoir  324  separated from the first ink reservoir  314  by the second wall  322  and separated from the third ink reservoir  320  by the first wall  318 . In some embodiments, the first wall  318  intersects the second wall  322  substantially at a right angle. However, it should be noted that the first wall  318  can intersect the second wall  322  at an angle other than a right angle.  
      Each of the four ink reservoirs  314 ,  316 ,  320 ,  324  can be generally rectangular, and can have a length and a width smaller than the length. In the illustrated embodiment of  FIGS. 11-14 , the length of the first ink reservoir  314  is substantially parallel with, and equal to, the length of the second ink reservoir  316 . Also in this embodiment, the width of the first ink reservoir  314  is substantially parallel with, and equal to, the width of the second ink reservoir  316 . Furthermore, the length of the third ink reservoir  320  can be substantially parallel with, and equal to, the length of the fourth ink reservoir  324 , and the width of the third ink reservoir  320  can be substantially parallel with, and equal to, the width of the fourth ink reservoir  324 . In some embodiments, the length of the third ink reservoir  320  and the length of the fourth ink reservoir  324  are oriented substantially orthogonally with respect to the length of the first ink reservoir  314  and the length of the second ink reservoir  316 .  
      The housing  312  can be generally rectangular, and can have a length and width smaller than the length. In the embodiment of  FIGS. 11-14 , the sum of the length of the first ink reservoir  314  (or the second ink reservoir  316 ) and the width of the fourth ink reservoir  324  (or the third ink reservoir  320 ) is approximately equal to the length of the housing  312 . Also in this embodiment, the sum of the lengths of the third and fourth ink reservoirs  320 ,  324  is approximately equal to the width of the housing  312 , and the sum of the widths of the first and second ink reservoirs  314 ,  316  is approximately equal to the width of the housing  312 .  
      Each of the four ink reservoirs  314 ,  316 ,  320 ,  324  has an upper portion  330  and a lower portion  332 , as shown in  FIG. 12 . As shown in  FIGS. 11-13 , each of the four ink reservoirs  314 ,  316 ,  320 ,  324  includes a filter tower  344 ,  354 ,  364 ,  374  positioned adjacent the lower portion  332  to which a filter can be coupled. The filter can take any form and can be coupled in any manner as described above with reference to the embodiment of  FIGS. 1-5 . In some embodiments, each of the filter towers  344 ,  354 ,  364 ,  374  is positioned near the intersection of the first wall  318  and the second wall  322 .  
      The housing  312  can have an outer surface  317  adapted to be covered by a chip (such as the chip  13  illustrated in the embodiment of  FIGS. 1-5 ). In some embodiments, the intersection of the first wall  318  and the second wall  322  is positioned over the outer surface  317  when the printhead  300  is oriented such that the outer surface  317  lies in a substantially horizontal plane and the nozzle  311  is pointed in a substantially downward direction.  
      As best shown in  FIGS. 11 and 13 , the first ink reservoir  314  is in fluid communication with a first filter tower  344  and first ink via  346 . The first ink via  346  has a first end  348  that opens into the first filter tower  344  and a second end  350  that opens to the outer surface  317 .  
      The second ink reservoir  316  in the embodiment of  FIGS. 11-14  is in fluid communication with a second filter tower  354  (see  FIG. 11 ) and a second ink via  356  (see  FIGS. 12 and 13 ). The second ink via  356  has a first end (not shown) that opens into the second filter tower  354  and a second end  360  that opens to the outer surface  317  (see  FIG. 14 ).  
      The third ink reservoir  320  in the embodiment of  FIGS. 11-14  is in fluid communication with a third filter tower  364  (see  FIGS. 11-13 ) and a third ink via  366  (see  FIGS. 12-13 ). The third ink via  366  has a first end  368  (see  FIG. 13 ) that opens into the third filter tower  364  and a second end  370  that opens to the outer surface  317  (see  FIGS. 13 and 14 ).  
      The fourth ink reservoir  324  in the embodiment of  FIGS. 11-14  is in fluid communication with a fourth filter tower  374  (see  FIG. 11 ) and a fourth ink via  376  (see  FIGS. 12 and 13 ). The fourth ink via  376  has a first end (not shown) that opens into the fourth filter tower  374  and a second end  380  that opens to the outer surface  317  (see  FIG. 14 ).  
      As shown in  FIG. 12 , the four ink vias  346 ,  356 ,  366 ,  376  can be positioned near the intersection of the first wall  318  and the second wall  322 , which allows all of the four ink reservoirs  314 ,  316 ,  320 ,  324  to be in fluid communication with the same outer surface  317  (and same chip, when a chip is coupled to the printhead  300 ). Further, a chip having four nozzle arrays can be coupled to the outer surface  317  such that each of the four ink reservoirs  314 ,  316 ,  320 ,  324  is in fluid communication with one of the four nozzle arrays on the chip.  
      As shown in  FIG. 14 , in some embodiments, the second end  350  of the first ink via  346  opens to the outer surface  317  at a position such that the second end  350  is between openings corresponding to other ink vias  356 ,  366 ,  376  (e.g., openings  360 ,  370 ,  380  in the illustrated embodiment of  FIGS. 11-14 ). However, it should be noted that the first ink reservoir  314  in the embodiment of  FIGS. 11-14  has a larger filter tower  344  than the other filter towers  354 ,  364 ,  374 , and can contain mono or black ink. Accordingly, in some embodiments, the second end  350  of the first ink via  346  opens to the outer surface  317  at a position that is not between openings corresponding to other ink vias, enabling the second end  350  and the first ink via  346  to be accessed more easily for service and maintenance. Such embodiments can be useful because mono or black ink is often the most frequently used ink.  
       FIG. 15  illustrates a printhead  400  according to another embodiment of the present invention, wherein like numerals represent like elements with respect to the printhead  300  illustrated in  FIGS. 11-14 . The printhead  400  shares many of the same elements and features described above with reference to printhead  300  of  FIGS. 11-14 . Accordingly, elements and features corresponding to elements and features in the printhead  300  of  FIGS. 11-14  are provided with the same reference numerals in the 400 series. Reference is made to the description above accompanying  FIGS. 11-14  for a more complete description of the features and elements (and alternatives to such features and elements) of the printhead  400  illustrated in  FIG. 15 .  
      The printhead  400  illustrated in  FIG. 15  includes a first ink reservoir  414 , a second ink reservoir  416 , a third ink reservoir  420 , and a fourth ink reservoir  424 . The first ink reservoir  414  has a larger volume than that of the other ink reservoirs  416 ,  420 ,  424 . In some embodiments, this larger volume is provided by a first ink reservoir  414  having a length greater than that of the second ink reservoir  416 . In the illustrated embodiment of  FIG. 15 , the housing  412  has a first length and a second length. The sum of the length of the first ink reservoir  414  and the width of the fourth ink reservoir  424  in  FIG. 15  is approximately equal to the first length of the housing  412 . The sum of the length of the second ink reservoir  416  and the width of the third ink reservoir  420  is approximately equal to the second length of the housing  412 .  
      The first ink reservoir  414  in the embodiment of  FIG. 15  is larger than the other ink reservoirs  416 ,  420 ,  424  such that the first ink reservoir  414  can contain mono or black ink, while the other ink reservoirs  416 ,  420 ,  424  can contain other colors. The first ink reservoir  414  has been made larger than the other ink reservoirs  416 ,  420 ,  424  by extending the length of the first ink reservoir as mentioned above. Making the first ink reservoir  414  larger in this manner affords the printhead  400  many of the same relationships and features of the printhead  300  illustrated in  FIGS. 11-14 . For example, the intersection of the first wall  418  and the second wall  422  can be positioned over the outer surface  417  (and over a chip, when a chip is coupled to the outer surface  417 ), and the four ink reservoirs  414 ,  416 ,  420 ,  424  can all be in fluid communication with the same outer surface (and chip, when a chip is coupled to the outer surface  417 ).  
      It should be noted that the printheads  10 ,  100 ,  200 ,  300 ,  400  described above and illustrated in  FIGS. 1-15  can include more than four ink reservoirs and maintain similar geometry and relationships without departing from the spirit and scope of the present invention.  
      In some embodiments described herein, the reservoirs are described as being separated by walls that are oriented substantially parallel with respect to one another or that intersect one another. In such cases, it should be noted that the walls can lie in planes oriented substantially parallel with respect to one another or that intersect one another.  
      The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.