Abstract:
A liquid ejection head module comprising:
       first and second head units disposed in a first direction, each of the first and second head units having first and second rows of liquid ejecting heads that comprises a plurality of nozzles disposed in the first direction, the first and second rows of liquid ejecting heads being disposed in a second direction crossing the first direction;   a first concavity and convexity on edge of the first head unit;   a second convexity and concavity on edge of the second head unit, the edge of the second head unit facing to the edge of the first head unit, at least one of the liquid ejecting heads being disposed at each of the first and second convexities,   wherein the first concavity and convexity and the second convexity and concavity are disposed in mating relation to one another.

Description:
The entire disclosure of Japanese Patent Application No: 2010-181416, filed Aug. 13, 2010 is expressly incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting head module that includes a liquid ejecting head for ejecting liquid through a nozzle aperture and a liquid ejecting apparatus and, more particularly, the invention relates to an ink jet recording head module and an ink jet recording apparatus. 
     2. Related Art 
     A liquid ejecting apparatus typified by an ink jet recording apparatus such as an ink jet printer, an ink jet plotter or the like includes a liquid ejecting head that is capable of ejecting a liquid such as ink or the like contained in an ink cartridge, an ink container or the like as liquid droplets. 
     Regarding the liquid ejecting head used as a single unit for the aforementioned liquid ejecting apparatus, it is difficult to extend nozzle apertures, i.e., increase the number of nozzle apertures, and to achieve high-density nozzle apertures due to the increased manufacturing cost thereof as well as impairment of yield thereof in a manufacturing process that is caused by an increase in size thereof. In view of such circumstances, e.g., WO 2004/022344 discloses a unitized liquid ejecting head unit, hereinafter referred to simply as a head unit, that includes a plurality of liquid ejecting heads held by a holder, which is a common plate therefor. 
     As regards the aforementioned head unit, an extended row of equally spaced nozzles can be formed in a first direction by staggering the liquid ejecting heads in the first direction. Incidentally, the liquid ejecting heads are staggered on the head unit as described above; more specifically, the plurality of the liquid ejecting heads are disposed side by side in the first direction in which the nozzle apertures are disposed side by side; and two rows formed by the plurality of the liquid ejecting heads disposed side by side in the first direction are further disposed side by side in a second direction that is perpendicular to the first direction in which the nozzle apertures are disposed side by side. The aforementioned two rows of the liquid ejecting heads disposed side by side in the second direction are slightly spaced apart from each other in the first direction. In addition to the above, as regards the two liquid ejecting heads disposed in contiguous relation to each other in the two rows, the nozzle apertures formed at an end of a first nozzle row disposed on a first liquid ejecting head and the other nozzle apertures formed at an end of a second nozzle row disposed on a second liquid ejecting head are configured to be aligned with each other in the first direction. Hereby, with the plurality of liquid ejecting heads, it is possible to consecutively form the nozzle rows by disposing the equally spaced nozzles side by side in the first direction, and it is further possible to perform printing across a wide area by utilizing the width of the consecutive nozzle rows. 
     Nevertheless, the needs arise for consecutively forming the extended equally spaced nozzle row in the first direction of the head unit to hold the plurality of the liquid ejecting heads to the common holder. However, in a case where any one of the liquid ejecting heads disposed on the head unit becomes faulty, it is necessary to dismount the head unit that has a faulty liquid ejecting head from the liquid ejecting apparatus and replace the faulty liquid ejecting head with a new one; as a result of the above, a problem of performing a complicated replacing process on the faulty liquid ejecting head arises. Incidentally, each liquid ejecting head of the head unit is connected to a liquid supplying tube, an electrical wiring or the like, and therefore, it is difficult to dismount only one faulty liquid ejecting head directly from the liquid ejecting apparatus. In addition, a new liquid ejecting head that replaces the faulty liquid ejecting head should be positioned relative to the nozzle apertures of the other liquid ejecting heads with high precision. Accordingly, it is necessary to dismount the head unit integrally formed with the plurality of the liquid ejecting heads, in which the faulty liquid ejecting head lies, from the liquid ejecting apparatus and replace the faulty integral head unit with a new one. 
     In addition to the above, the extended nozzle row that is extended beyond the length of the head unit without being limited to the length of the nozzle row on a single head unit is made possible by disposing the plurality of head units side by side and modularizing the plurality of head units without mounting numerous liquid ejecting heads on the single head unit. However, a problem concerning the aforementioned description is an increase in size of a head module in the second direction that is perpendicular to the first direction due to the head units having to be staggered in order to configure the nozzle row, in which the equally spaced nozzle apertures are disposed consecutively in the first direction. 
     Further, the nozzle rows of the head module, which have an increased size in the second direction, are disposed at a different position from each other in the second direction, therefore, another problem is that printing quality is impaired due to a deviation in a timing when liquid droplets, such as ink droplets, land on a recording medium to be printed and a color-difference caused by a difference in an amount of smearing of liquid on the recording medium to be printed. 
     The problems as described above exist in not only a head module provided with an ink jet recording head that ejects ink but also a liquid ejecting head module with a liquid ejecting head that ejects a liquid other than ink. 
     SUMMARY 
     An advantage of some aspects of the invention is that it provides a liquid ejecting head module and a liquid ejecting apparatus which are capable of decreasing in size and enhancing printing quality by disposing nozzle rows adjacent one another. 
     According to a first aspect of the invention for resolving the problems as described above, the liquid ejecting head module includes a plurality of holders; a plurality of head units, each of which has one of the plurality of holders, disposed side by side in a first direction; a plurality of liquid ejecting heads held by each holder and disposed side by side on each holder in the first direction; a plurality of nozzle apertures, through which liquid is ejected, formed on each liquid ejecting head; a plurality of projecting portions, each of which is provided with one of the plurality of liquid ejecting heads, formed at each opposite end of each holder of the plurality of head units disposed in contiguous relation to one another in the first direction; and a plurality of cut-off portions formed at each opposite end of each holder of the plurality of head units disposed in contiguous relation to one another in the first direction, wherein the plurality of head units disposed side by side in the first direction are further disposed in side by side parallel rows in a second direction that is perpendicular to the first direction, and the plurality of projecting portions and the plurality cut-off portions of the head units disposed in contiguous relation to one another in the first direction are disposed in mating relation to one another so that the liquid ejecting heads disposed on each opposite projecting portion formed at each contiguous ends of the head units are disposed in overlapping relation to one another in the second direction. 
     The above-mentioned first aspect of the invention permits a manufacturing yield to be enhanced and further permits the nozzle row to be extended by the plurality of the head units. In addition to the above, the plurality of head units can be disposed linearly in the first direction and can be further decreased in size by decreasing the width of the head unit in the second direction; and thereby negating the need to dispose the nozzle rows of the plurality of the head units at different positions from each other in the second direction, the first aspect of the invention is further capable of restraining a color difference, a stripe or the like caused by a difference in an amount of smearing of liquid due to a deviation in a timing when liquid droplets land on a recoding medium to be printed from occurring. 
     Incidentally, each head unit is provided with a connector that is electrically connected to an external wiring as well as the each liquid ejecting head. It is, therefore, preferable that the connector be disposed so as to be connected to the external wiring at a side opposite from a liquid ejecting side where the nozzle aperture of the liquid ejecting head is open. It is further preferable that the connector be disposed at the exterior of the head unit in the second direction in which the liquid ejecting heads are disposed in side by side parallel rows. Thereby, the connector is disposed in an exterior region where the liquid ejecting head is disposed, it becomes possible to partition off the head unit into the region where the liquid ejecting head is disposed in the second direction and the exterior region where the connector is disposed; accordingly, it further becomes possible to easily arrange a tube for supplying a liquid to the liquid ejecting head, the external wiring that is connected to the connector or the like, and to decrease in size. 
     What is more, as regards the connectors which lie between the two adjacent rows of the head units, it is furthermore preferable that one connector of a first row of the head units and the other connector of a second row of the head units be disposed so as to be spaced apart from each other in the first direction; wherein the plurality of the head units disposed side by side in the first direction are disposed in side by side adjacent rows in the second direction. Hereby, in a case where the rows of the plurality of head units disposed side by side in the first direction are disposed side by side in the second direction, the row of the plurality of head units can be further decreased in size in the second direction, because the connectors of the adjacent rows of the head units will not interfere one another. 
     In addition to the above, it is furthermore preferable that a boundary of the holder between the region where the connector is disposed and the nozzle apertures side be a thin wall portion of which the thickness is smaller than those of another regions. By forming the thin wall portion as described above, it hereby becomes possible to suppress deleterious effects of applied force to the region where each liquid ejecting head is held, by causing only the region where the connector is disposed to undergo elastic deformation caused by applied force to the connector when the external wiring is connected to the connector and disconnected therefrom. 
     Further, it is still furthermore preferable that a space be formed between the holder and a substrate on which the connector is disposed. By forming a space therebetween, it hereby becomes possible to suppress deleterious effects of applied force to the region where the liquid ejecting head is held, because the region of the holder where the connector is disposed will not undergo elastic deformation caused by applied force to the connector when the external wiring is connected to the connector and disconnected therefrom. 
     Furthermore, according another aspects of the invention, a liquid ejecting apparatus includes the liquid ejecting head module in accordance with the aspects of the invention as describe above. The above-mentioned another aspects of the invention are capable of providing the liquid ejecting apparatus that can perform printing on a large sized recording medium to be printed and can be further decreased in size. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is an exploded perspective view of a head unit according to a first embodiment of the invention. 
         FIG. 2  is an assembled cross-sectional view of the head unit according to the first embodiment of the invention. 
         FIG. 3  is an exploded perspective view of a recording head according to the first embodiment of the invention. 
         FIG. 4  is an assembled cross-sectional view of the recording head according to the first embodiment of the invention. 
         FIG. 5  is a schematic perspective view of a head module according to the first embodiment of the invention. 
         FIG. 6  is a plan view of the head module according to the first embodiment of the invention. 
         FIG. 7  is a schematic cross-sectional view of the head module according to the first embodiment of the invention. 
         FIG. 8  is a plan view illustrating a conventional configuration of the head module. 
         FIG. 9  is a plan view illustrating a modification of the head module according to the first embodiment of the invention. 
         FIG. 10  is a schematic cross-sectional view of a recording apparatus according to the first embodiment of the invention. 
         FIGS. 11A and 11B  are cross-sectional views of a head unit according to a second embodiment of the invention. 
         FIGS. 12A and 12B  are cross-sectional views of the head unit according to a third embodiment of the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The present invention will be hereinbelow described in detail according to preferred embodiments. 
     First Embodiment 
     First, an ink jet recording head unit, hereinafter referred to simply as a head unit, an example of a liquid ejecting head unit according to a first embodiment of the invention, will be hereinbelow described. Here,  FIG. 1  is an exploded perspective view of the ink jet recording head unit and  FIG. 2  is an assembled cross-sectional view thereof. 
     As illustrated in  FIGS. 1 and 2 , a head unit  10  includes a plurality of recording heads  20  for ejecting ink droplets; a case  60  as a holder for holding the recording head  20  thereto; a fluid passage member  80  disposed on a side of the case  60  opposite from the recording head  20 ; and a circuit substrate  90  disposed between the case  60  and the fluid passage member  80 . 
     Reference is hereby made to  FIGS. 3 and 4  to describe an example of a configuration of the recording head  20  to begin with. Here,  FIG. 3  is an assembled perspective view of the recording head  20  according to the first embodiment of the invention and  FIG. 4  is a cross-sectional view of a pressure generating chamber  22  of the recording head  20  in the longitudinal direction thereof. 
     As illustrated in  FIGS. 3 and 4 , a fluid passage forming substrate  21  that forms the recording head  20  includes a plurality of the pressure generating chambers  22  disposed in side by side two rows in the lateral direction thereof. In addition, a communicating portion  23  is formed in a longitudinal exterior region of each pressure generating chamber  22  of the row, wherein the communicating portion  23  and each pressure generating chamber  22  communicate with each other through an ink supplying passage  24  and a communicating passage  25  disposed in every pressure generating chamber  22 . 
     A nozzle plate  27  includes a nozzle opening  26  that extends therethrough and communicates with each corresponding pressure generating chamber  22  in the vicinity of an end of the pressure generating chamber  22  opposite from the ink supplying passage  24 , and the nozzle plate  27  is bonded to one side of the fluid passage forming substrate  21 . 
     On the other hand, piezoelectric elements  30  are formed on the other side of the fluid passage forming substrate  21  opposite from the nozzle plate  27  through an elastic film  28  and an insulator film  29 . Each of the piezoelectric elements  30  includes a first electrode  31 , a piezoelectric body layer  32  and a second electrode  33 . The second electrode  33  that forms each of the piezoelectric elements  30  is connected to a lead electrode  34  that extends over the insulator film  29 . The lead electrode  34  is connected to the second electrode  33  at a first end thereof, and is further connected to a driving wiring  35  composed of a flexible wiring member, i.e., a COF substrate, that is provided with a driving IC  35   a  for driving the piezoelectric elements  30  at a second end thereof. Thus, the driving wiring  35  is connected to the lead electrode  34  at a first end thereof and is secured to the circuit substrate  90  at a second end thereof, refer to  FIG. 2 . 
     A protective substrate  37  that is provided with piezoelectric elements retainers  36 , which are spaces for protecting the piezoelectric elements  30 , in a region opposite to the piezoelectric elements  30  is bonded to a surface of the fluid passage forming substrate  21 , on which the aforementioned piezoelectric elements  30  are formed, by means of an adhesive agent  38 . In addition to the above, the protective substrate  37  is provided with manifold portions  39 . According to the first embodiment of the invention, the manifold portions  39 , which communicate with the communicating ports  23  of the fluid passage forming substrate  21 , form manifolds  40 , i.e., a common ink chamber for each pressure generating chamber  22 . 
     Further, the protective substrate  37  is provided with a through hole  41  that is formed in the thickness direction thereof. The through hole  41  is disposed between the two piezoelectric elements retainers  36  according to the first embodiment of the invention. In addition, the lead electrode  34  that extends from each piezoelectric elements  30  is disposed such that a vicinity of one end of the lead electrode  34  is exposed through the through hole  41 . 
     Furthermore, a compliance substrate  46  that includes a sealing film  44  and a fixing plate  45  is bonded to an upper surface of the protective substrate  37 . The sealing film  44  is composed of a material that possesses low stiffness and flexibility, and one side of the manifold portion  39  is sealed with the sealing film  44 . Furthermore, the fixing plate  45  is made of a hard material such as metal. Since a region of the fixing plate  45  opposite to the manifold  40  is completely bored through in the direction of thickness thereof so as to form an opening portion  47 , one side of the manifold  40  is sealed with only the flexible sealing film  44 . In addition to the above, the compliance substrate  46  is provided with an ink lead-in port  48  so as to guide ink into the manifold  40 . 
     A head case  49  is secured to the compliance substrate  46 . The head case  49  is provided with an ink lead-in passage  50  that communicates with the ink lead-in port  48  and supplies ink to the manifold  40  from a container such as a cartridge. The head case  49  is further provided with a wiring member retaining hole  51  that communicates with the through hole  41  formed through the protective substrate  37 . The driving wiring  35  disposed through the wiring member retaining hole  51  is connected to the lead electrode  34  at one end thereof. 
     Each recording head  20  formed as described above is secured to the case  60 . As illustrated in  FIGS. 1 and 2 , a plurality of the recording heads  20 , four recording heads  20  according to the first embodiment of the invention, are secured to a bottom surface of the case  60 . Hereby, an extended row of equally spaced nozzles can be formed in a first direction by staggering the plurality of recording heads  20  in the first direction. The plurality of recording heads  20  are staggered as described above, that is; the plurality of the recording heads  20  are disposed side by side in the first direction in which the nozzle apertures  26  are disposed side by side; and two rows which include the plurality of the recording heads  20 , two recording heads  20  per one row, are spaced apart from each other in a second direction that is perpendicular to the direction, i.e. the first direction, in which the nozzle apertures  26  are disposed side by side. The aforementioned two rows of the recording heads  20  disposed side by side in the second direction are so disposed that they are slightly spaced apart from each another in the first direction. In addition to the above, as regards the two adjacent rows of the recording heads  20 , the nozzle apertures  26  formed at one end of a first nozzle row of the recording heads  20  and the other nozzle apertures  26  formed at the other end of a second nozzle row thereof are configured so as to be aligned with each other in the first direction in which the nozzle apertures  26  are disposed side by side. Hereby, with the plurality of the recording heads  20 , four recording heads  20  according to the first embodiment of the invention, it is possible for the nozzle row to be formed consecutively by disposing the equally spaced nozzle apertures  26  side by side so as to be extended as long as the length of four recording heads  20  in the first direction; as a result of the above, it is further possible to perform printing across a wide area by utilizing the width of the consecutive nozzle row. 
     The case  60  that retains the recording head  20  as described above is rectangularly shaped, when viewing a top thereof from a cover  82 , and is further shaped in such manner that a pair of diagonal corners thereof appear to have been cut off. The case  60  is rectangularly shaped such that long sides of the rectangle extend along the above-mentioned first direction according to the first embodiment of the invention. 
     Incidentally, the case  60  is rectangularly shaped in such manner that a pair of diagonal corners thereof appear to have been cut off; that will be hereinbelow described. 
     As regards the case  60 , a projecting portion and a cut-off portion, which are rectangularly shaped when viewed from above and formed at each end thereof in the longitudinal direction, are disposed side by side in the lateral direction. The projecting portion and the cut-off portion are further disposed so as to be directly opposite each other at each end of the case  60  in the longitudinal direction. The aforementioned cut-off portions are shaped such that the pair of diagonal corners of the case  60  appear to have been cut off as described above. The projecting portion and the cut-off portion will be later described in detail. 
     In addition, the case  60  includes extending portions  63  disposed on both long sides thereof in such manner that the partial long sides extend outwardly in the direction of short sides. More specifically, the case  60  includes the extending portions  63  disposed extendedly on both long sides in the second direction. A connector  92  of a circuit substrate  90 , which will be later described in detail, is oppositely disposed relative to the extending portion  63 . 
     The case  60  is further provided with through holes  61 , which are formed therethrough in the thickness direction thereof and correspond to each recording heads  20 . A supply passage  62 , which communicates with the ink lead-in passage  50  disposed in the head case  49  of the recording head  20 , is disposed on the exterior of the through hole  61  of the case  60 . Furthermore, the driving wirings  35  of each recording head  20  are disposed through the through hole  61 ; the head case  49  of each recording head  20  is joined to an outer peripheral portion of the through hole  61  with a communication state between the ink lead-in passage  50  and a supply passage  62 . 
     Incidentally, a cover head  70  provided with an opening  71 , through which the nozzle apertures  26  are exposed, is secured to a bottom side of the nozzle plate  27  of each recording head  20  secured to the case  60 . 
     The fluid passage member  80  is secured to a side of the case  60  opposite from the recording head  20  through the circuit substrate  90  and a sealing member  95  that is composed of a material such as rubber. 
     The circuit substrate  90  includes a plate-shaped member, on which electric components for driving the piezoelectric elements  30  and various kinds of wirings are mounted, which are not illustrated particularly. The circuit substrate  90  is further provided with a connecting hole  91  that is disposed therethrough in the thickness direction. In addition, the driving wirings  35  of each recording head  20  are disposed through the connecting hole  91 , and ends of the driving wirings  35  are electrically connected to the various kinds of wirings or the like. 
     In addition to the above, the circuit substrate  90  is substantially rectangularly shaped, when viewed from above, and is further shaped in such manner that a pair of diagonal corners thereof appear to have been cut off. The circuit substrate  90  is further shaped in such manner that long sides of the rectangle extend along the direction of short sides thereof; i.e., the circuit substrate  90  is shaped similarly to the case  60  and an outside shape of the circuit substrate  90  is slightly smaller in size than that of the case  60 . The circuit substrate  90  is further provided with the connectors  92  disposed on portions extended outwardly from both long sides of the rectangle thereof. 
     The connector  92  is secured to the circuit substrate  90  so that a connecting port  93 , to which an external wiring is connected and from which the external wiring is disconnected, is open towards the fluid passage member  80  as illustrated in  FIG. 1 . 
     The fluid passage member  80  includes a main body of the fluid passage member  81  and the cover  82 . The aforementioned circuit substrate  90  and the sealing member  95  are retained between the main body of the fluid passage member  81 , which constitutes the fluid passage member  80 , and the case  60 . 
     In addition to the above, the main body of the fluid passage member  81  includes a securing member  83  and a fluid passage forming member  84  that is disposed so as to project downwardly from a bottom side of the securing member  83 ; a plurality of ink supply needles  100  are secured to one side of the securing member  83 ; and ink supply tubes connected to an ink container that contains ink are secured to the plurality of ink supply needles. An ink supply aperture  85  that is open at one end thereof opposite to the ink supply needle  100  is formed in each fluid passage forming member  84 . Additionally, the other end of the ink supply aperture  85  is connected to the supply passage  62  of the case  60  through a supply communicating passage  96  disposed in the sealing member  95 . 
     Further, the main body of the fluid passage member  81  substantially has a rectangular shape that coincides with the rectangular shape of the case  60  excluding the connectors  92  when viewed from above; i.e., the main body of the fluid passage member  81  is substantially rectangularly shaped in such manner that a pair of diagonal corners thereof appear to have been cut off when viewed from above. Hereby, portions where the connectors  92  of the circuit substrate  90  are disposed will not be covered by the main body of the fluid passage member  81  upon securing the main body of the fluid passage member  81  to the case  60 . 
     Incidentally, a filter  110  for removing air bubbles and foreign substances from ink is disposed at an opening portion of one end of the ink supply aperture  85 ; i.e., the ink supply needle  100  is secured to the securing member  83  of the main body of the fluid passage member  81  through the aforementioned filter  110 . 
     Each ink supply needle  100  is provided with a through passage  101  that communicates with the ink supply aperture  85  therewithin. Further, it is configured such that ink from the ink container is supplied to the manifold  40  of the recording head  20  through the ink supply tube, not illustrated, the through passage  101  of the ink supply needle  100 , the ink supply aperture  85 , the ink supply passage  62  or the like, by inserting the ink supply needle  100  into the ink supply tube. 
     The cover  82  substantially has a box-like-shape, of which an inferior surface side, i.e., the side opposite to the recording head  20 , is open; the cover  82  is integrally attached to the main body of the fluid passage member  81  in such manner that the cover  82  overlaps the main body of the fluid passage member  81  from a side of the ink supply needle  100 . The cover  82  is further shaped similarly to the case  60  when viewed from above; the cover  82  is furthermore similar in size to the case  60  when viewed from above; and the main body of the fluid passage member  81  and the circuit substrate  90  are included between the cover  82  and the case  60 . More specifically, the cover  82  is provided with a bottom surface portion, which is a superior surface portion when viewed from below,  86  that is provided with an opening  87  for exposing the ink supply needle  100  therethrough and a wall portion  88 , which is formed so as to enclose the fluid passage forming member  84  along a periphery thereof and upwardly extend to the case  60 . 
     As illustrated in  FIG. 2 , the cover  82  and the case  60  are secured to each other by using a fastening member  120  such as a screw or the like under the following conditions; i.e., the aforementioned cover  82  overlaps the main body of the fluid passage member  81  from the ink supply needle  100  side, and the circuit substrate  90  and the sealing member  95  are interposed between the main body of the fluid passage member  81  and the casing  60 . Hereby, the fluid passage member  80  is formed upon integrating the fluid passage member  81  with the cover  82 ; and furthermore, the fluid passage member  80  is integrated with the case  60 . In accordance with the first embodiment of the invention, the fluid passage member  80  and the casing  60  are secured to each other by four fastening members  120  disposed on the individual sides thereof, refer to  FIG. 1 . 
     In the configuration of the recording head  20  according to the first embodiment of the present invention as described above, the circuit substrate  90 , on which electronic components or the like for driving the piezoelectric elements  30  are mounted, is covered with the fluid passage member  80  and the case  60 . More specifically, the circuit substrate  90  is accommodated in an intervening space formed between the cover  82  and case  60 . Hereby, ink mist, which is generated by ejecting ink droplets through the nozzle aperture  26  of the recording head  20 , can be efficiently prevented from adhering to the circuit substrate  90 . 
     Incidentally, as described above, the circuit substrate  90  is provided with the connectors  92 , which the external wirings, not illustrated, are connected. As illustrated in  FIGS. 1 and 2 , the connectors  92  are disposed at portions which project from opposite corners of the substantially rectangularly shaped circuit substrate  90 . The connector  92  is further secured to the circuit substrate  90  so that the connecting port  93 , to which and from which the external wiring is connected and disconnected, is open towards the fluid passage member  80  as illustrated in  FIG. 2 . An exposing opening  89  for exposing the connecting port  93  of the connector  92  therethrough is formed in a region opposite to the connector  92  of the cover  82  that constitutes the fluid passage member  80 . Put another way, the connecting port  93  of the connector  92  can be connected to the external wiring and disconnected therefrom from the exterior of the fluid passage member  80  through the exposing opening  89 . 
     Additionally, as described above, the case  60  and the fluid passage member  80  are secured to each other by using four fastening members  120  through the circuit substrate  90  that is interposed therebetween, refer to  FIG. 1 . 
     As regards the head unit  10  as described above, the plurality of head units  10  secured to a fixing member constitute an ink jet recording head module, one example of a liquid ejecting head module. 
     The ink jet recording head module, hereinafter referred to simply as a head module, that is an example of the liquid ejecting head module according to the first embodiment of the invention will be hereinbelow described. For reference sake,  FIG. 5  is a schematic perspective view illustrating the ink jet recording head module, which is an example of the liquid ejecting head module according to the first embodiment of the invention;  FIG. 6  is a plan view of the head module; and  FIG. 7  is a schematic cross-sectional view of the head module. 
     As illustrated in the above-mentioned drawings a head module  200  according to the first embodiment of the invention is provided with the plurality of the head units  10  and a fixing member  210  for fixing the plurality of the head units  10  thereto. 
     The fixing member  210  is composed of a plate-shaped member. As illustrated in  FIG. 7 , the fixing member  210  is provided with a fixing through hole  211 , through which one end of the case  60  of the head unit  10  opposite to the recording head  20  and the recording head  20  are capable of being disposed when the head unit  10  is fixed to the fixing member  210 . Since the fixing through hole  211  has a slightly smaller opening area than that of the other end of the case  60  opposite to the fluid passage member  80 , an end surface of the case  60  abuts against a surface of the fixing member  210  in a state that only a portion of the case  60  opposite to the recording head  20  is disposed through the fixing through hole  211 . Accordingly, the head unit  10  is fixed to the fixing member  210  in a state that the end surface of the case  60  abuts against the surface of the fixing member  210 . 
     As described above, the head unit  10  has a rectangular shape with a pair of diagonal cut-off corners, when viewed from above, i.e., viewed from the side opposite from the fixing member  210 . 
     The detailed shape of the head unit  10  will be hereinbelow described. The head unit module  200  according to the first embodiment of the invention is provided with the head units  10  linearly disposed side by side in the first direction Y. In addition to the above, projecting portions,  11  and  13 , and cut-off portions,  12  and  14 , are formed at individual opposite corners of a holder, such as the case  60  or the fluid passage member  80 , for the head units  10  disposed in contiguous relation to each other in the first direction Y. More specifically, as regards the two head units disposed in contiguous relation to each other in the first direction Y, a first projecting portion  11  and a first cut-off portion  12  are disposed at a first end of a first head unit  10 A that is contiguous to a second head unit  10 B. On the other hand, a second projecting portion  13  and a second cut-off portion  14  are disposed at a second end of the second head unit  10 B that is contiguous to the first head unit  10 A. 
     Hereby, the first projecting portion  11  of the first head unit  10 A is disposed so as to project towards the second head unit  10 B with the first cut-off portion  12  that is formed by cutting a corner of the rectangularly shaped holder off in a rectangular shape. In other words, the first projecting portion  11  and the first cut-off portion  12  are disposed side by side in the second direction X. Likewise, the second projecting portion  13  of the second head unit  10 B is disposed so as to project towards the first head unit  10 A with the second cut-off portion  14  that is formed by cutting the corner of the rectangularly shaped holder off in the rectangular shape. In addition, a side by side arrangement of the first projecting portion  11  and the first cut-off portion  12  of the first head unit  10 A and the side by side arrangement of the second projecting portion  13  and the second cut-off portion  14  of the second head unit  10 B are opposite to each other. More specifically, as regards the two head units  10 A and  10 B contiguously disposed in the first direction Y, the second cut-off portion  14  of the second head unit  10 B is oppositely disposed relative to the first projecting portion  11  of the first head unit  10 A; likewise, the first cut-off portion  12  of the first head unit  10 A is oppositely disposed relative to the second projecting portion  13  of the second head unit  10 B. 
     The recording heads  20  are disposed on the aforementioned head units  10 A and  10 B in such manner that the nozzle apertures  26  are disposed side by side in the first direction Y. The rows of the recording heads  20  disposed side by side in the first direction Y are further disposed side by side in the second direction X, two rows according to the first embodiment of the invention, on the head units  10 ; a first row of the recording heads  20  is disposed so as to be spaced apart from a second row of the recording heads  20  in the first direction Y. More specifically, as regards the first head unit  10 A, a first row of the recording heads  20  is displaced relative to a second row thereof in the first direction Y so as to dispose one recording head  20  on the first projecting portion  11 . Likewise, as regards the second head unit  10 B, a first row of the recording heads  20  is displaced relative to a second row thereof in the first direction Y so as to dispose one recording head  20  on the second projecting portion  13 . 
     More specifically, as regards the respective head units  10 A and  10 B, since the first row of the recording heads  20  is displaced relative to the second row in the first direction Y, the first row of the recording heads  20  is disposed so as to project relative to the second row at first ends of the head units  10 A and  10 B in the first direction; while the second row of the recording heads  20  is disposed so as to project relative to the first row at second ends of the head units  10 A and  10 B. Thus, the cut-off portions  12  and  14  are disposed in spaces formed as a result of projecting of the first row of the recording heads  20 ; i.e., the cut-off portions  12  and  14  are disposed in regions formed as a result of retracting the second row of the recording heads  20  relative to the first row in the first direction Y. 
     In accordance with the first embodiment of the invention, as regards the head units  10 A and  10 B disposed in contiguous relation to each other in the first direction Y, the first projecting portion  11 , the first cut-off portion  12 , the second projecting portion  13  and the second cut-off portion  14  are further disposed respectively at second ends of the head units  10 A and  10 B opposite from the first ends where the head units  10 A and  10 B are oppositely disposed relative to each other. More specifically, the first projecting portion  11  and the first cut-off portion  12  are disposed at a first end where the first head unit  10 A is contiguous with the second head unit  10 B; while the second projecting portion  13  and the second cut-off portion  14  are disposed at a second end of the first head unit  10 A opposite from the second head unit  10 B in the first direction Y. Likewise, the second projecting portion  13  and the second cut-off portion  14  are disposed at a first end where the second head unit  10 B is contiguous with the first head unit  10 A; while the first projecting portion  11  and the first cut-off portion  12  are disposed at a second end of the second head unit  10 B opposite from the first head unit  10 A in the first direction Y. In other words, both first and second ends of the head units  10 A and  10 B in the first direction Y have a rotationally symmetric configuration. Hereby, the positions of the head units  10 A and  10 B can be interchanged in the first direction Y relative to each other when the projecting portions,  11  and  13 , and the cut-off portions,  12  and  14 , are disposed in mating relation to each other upon disposing the head units  10  side by side in the first direction Y, this will be described in further detail later; as a consequence of the above, cost can be reduced by mass-producing the similarly shaped head units  10  in comparison with manufacturing of differently shaped head units. 
     In addition to the above, the head unit  10  extends outwardly as far as the connector  92  from both long sides thereof in the direction of short sides thereof, i.e., in the second direction X. The extending portion  63 , which extends outwardly from a first long side of the head unit  10 , is disposed at side of the first end thereof, as illustrated in the center of  FIG. 6 , in the first direction Y so as to be disposed at the side opposite from the first cut-off portion  12  in the second direction X. Further, the extending portion  63 , which extends outwardly from a second long side of the head unit  10 , is not disposed at side of the first end of the head unit in the first direction Y but at a position displaced from the first end thereof in the first direction Y towards the center along the second long side thereof so as to be disposed at the side opposite from the second projecting portion  14  in the second direction X. 
     In addition to the above, the row of the head units  10  is formed by disposing the above-mentioned head units  10 A and  10 B side by side in the first direction Y. The head units  10  are linearly disposed in the first direction Y according to the first embodiment of the invention. In such a case as described above, as regards the head units  10 A and  10 B disposed in contiguous relation to each other in the first direction Y, the recording heads  20 , which are disposed at the individual projecting portions  11  and  13  of the contiguous head units  10 A and  10 B, are disposed in overlapping relation to each other in the second direction X by disposing the projecting portions  11  and  13 , and the cut-off portions  12  and  14 , in mating relations to each other. 
     More specifically, as regards the head units  10 A and  10 B disposed in contiguous relation to each other in the first direction Y, the first projecting portion  11  of the head unit  10 A is disposed in mating relation with the second cut-off portion  14  of the head unit  10 B. The second projecting portion  13  of the head unit  10 B is likewise disposed in mating relation with the first cut-off portion  12  of the head unit  10 A. Hereby, first projecting portion  11  is disposed in mating relation with the second cut-off portion  14 ; and in addition, the second projecting portion  13  is disposed in mating relation with the first cut-off portion  12 . According to the first embodiment of the invention, what is described herein refers to the head units  10 A and  10 B disposed in contiguous relation to each other in the first direction Y with the projecting portions  11  and  13  and the cut-off portions  12  and  14  disposed in mating relation to one another. 
     Incidentally, an arrangement of the head units  10 A and  10 B disposed in mating relation to each other in the first embodiment of the invention, as described herein, refers to the head units  10 A and  10 B in a mutually mated condition with outer end shapes thereof, when viewed from above. In addition, since the head units  10 A and  10 B disposed in mating relation to each other in the first embodiment of the invention is defined as only mating relation between the outer end shapes of the head units  10 A and  10 B, the aforesaid definition allows, e.g., gaps to be provided therebetween. 
     The head units  10 A and  10 B can be linearly disposed side by side in the first direction Y by thus disposing the projecting portions and the cut-off portions thereof in mating relation to one another. For reference sake, the head units  10 A and  10 B disposed side by side in the first direction are herein referred to as the head units  10 A and  10 B, of which both two rows of the recording heads  20  disposed in substantially the same position in the second direction X. The head unit  10 A and  10 B, therefore, may be slightly spaced apart from each other in the second direction X. 
     Additionally, by disposing the recording heads  20  provided on the individual projecting portions of the head units  10 A and  10 B, which are disposed in contiguous relation to each other, in overlapping relation to one another in the second direction X, the nozzles rows of the first head unit  10 A can be disposed in substantially the same position as the nozzles rows of the second head unit  10 B in the second direction X; and in addition, the individual nozzles rows of the first head unit  10 A and the second head unit  10 B can be further consecutively disposed in the first direction Y. More specifically, the nozzles rows formed by the two rows of the recording heads  20  disposed on the first head unit  10 A and the second head unit  10 B can be disposed in substantially the same position in the second direction X. On account of the above, the head module  200  can be decreased in size without having to be increased in size in the second direction X. Adding to the above, since the two head units  10 A and  10 B can be linearly disposed side by side in the first direction Y, it becomes possible to enhance printing quality by restraining a timing when ink droplets ejected from the two head units  10  land on a recording medium to be printed from being deviated, and further by restraining a color-difference and a stripe caused by a difference in an amount of swearing of ink droplets on the recording medium to be printed from occurring. 
     Incidentally, as illustrated in  FIG. 8 , a conventional head unit  310 , which is not provided with the projecting portions  11  and  13  and the cut-off portions  12  and  14 , requires that the two head units  310  be spaced apart from each other in the second direction X so as to dispose the nozzles rows thereof in overlapping relation to one another in the first direction Y. In a case where the head units  310  are thus disposed, the width Wa 2  of the two head units  310 , which configure the nozzles rows consecutively disposed in the first direction Y, with a space interposed therebetween in the second direction X is increased to a considerable extent; and in addition, the two nozzles rows of the two head units  310  are spaced apart from each other by the width Wb 1  in the second direction X. As a consequence of the above, the timing when ink droplets land on the recording medium to be printed is deviated and the color-difference and the stripe caused by the difference of in the amount of smearing of ink droplets on the recording medium to be printed occur; therefore, printing quality is impaired as a result of the above. In accordance with the first embodiment of the invention, by disposing the two head units  10 , which configure the nozzles rows consecutively disposed in the first direction Y, the width Wa 1  of two rows of the head units  10  in the second direction X can be narrower than the width Wa 2  of two rows of the head units  310  with a space interposed therebetween; and moreover, a space interposed between the two nozzles rows disposed on the two head units  10  in the second direction X can be further eliminated. 
     In addition to the above, according to the first embodiment of the invention, the connectors  92  are disposed in regions which extend outwardly from both long sides of the head unit  10  along the second direction X as described above. More specifically, a first connector  92  is disposed at a side of the second projecting portion  13  of the head unit  10 B opposite from the first cut-off portion  12  in the second direction X. Further, a second connector  92  is disposed at a side of the first cut-off portion  12  of the head unit  10 B opposite from the second projecting portion  13  in the second direction X; however, a second connector  92  is disposed at a position displaced towards the center from the first end of the head unit  10 B along the aforementioned side. The head units  10  can hereby be disposed side by side in the first direction Y so as to consecutively dispose the nozzles rows thereon without interference from the connectors  92 . In addition, by disposing the connectors  92  at both outsides of the rows of the recording heads  20  in the second direction X, the rows of the head units  10  can be disposed in overlapping relation to each other in the first direction Y when the rows of the head units  10  disposed side by side in the first direction Y are further disposed side by side in the second direction X without overlapping of the connectors  92 . More specifically, as regards the connectors  92  disposed between two opposite rows of the head units  10 , the connectors  92  of the first row of the head units  10  and the second row of the head units  10  are spaced apart from one another in the first direction Y. Since the connectors  92  disposed between the rows of the head units  10  can be hereby arranged in overlapping relation to one another in the first direction Y, a space interposed between the two opposite rows of the head units  10  can be narrowed, and the head module  200  can be further decreased in size in the second direction X. What is more, by disposing the connectors  92  at the exterior of the rows of the recording heads  20  disposed on the individual head units  10 , a first region where the plurality of the recording heads  20  is disposed in overlapping relation to one another and a second region where a plurality of the connectors  92  is disposed in overlapping relation to one another in the second direction X can be disposed in an alternating sequence. Accordingly, the ink tube or the like for supplying ink to the recording head  20  and the external wiring connected to the connector  92  can be easily disposed in the alternating sequence; and moreover, the ink tube and the external wiring can be bundled together, and can be consequently easily connected to the recording head  20  and the connector  92 . In other words, while the recording head  20  is connected to the ink tube for supplying ink and the connector  92  is connected to the external wiring for supplying a printing signal thereto, it is hard to dispose the ink tube and the external wiring because a plurality of ink tubes are connected to the plurality of the recording heads  20 . According to the first embodiment of the invention, a region where the recording heads  20  are disposed and a region where the connectors  92  are disposed can be partitioned off from each other in the second direction X. Hence, the ink tubes can extend longitudinally from the same position in the second direction X to the plurality of the recording heads  20  along the first direction Y. The external wiring can likewise extend longitudinally from the same position in the second direction X to the plurality of connectors  92  along the first direction Y. Accordingly, the plurality of the ink tubes and a plurality of the external wirings can be disposed in the bundled ink tubes and in the bundled external wirings respectively; as a result of a simplified arrangement of the ink tubes and the external wirings for the recording heads  20  and the connectors  92  as described above, the head module  200  can be decreased in size. 
     Incidentally, the connectors  92  disposed between the rows of the head units  10  are arranged in overlapping relation to one another in the first direction Y according to the first embodiment of the invention, however, it should be understood that the invention is not particularly limited thereto. For instance, as illustrated in  FIG. 9 , the connectors  92  of the individual head units  10  of a head module  200 A may be disposed at of both end sides thereof in the direction Y. In the aforementioned case, it is required that the connectors  92  be spaced a distance away from the positions thereof illustrated in  FIG. 6  so as to avoid mutual overlapping of the connectors  92  when the two rows of the head units  10  are disposed side by side in the second direction X. However, such arrangement of the head units  10  as illustrated in  FIG. 9  still permits the head module  200 A to be decreased in size in comparison with an arrangement of the head units  10  as illustrated in  FIG. 8 . As a matter of course, in a case where only one row of the head units  10  is disposed on the head modules  200  and  200 A in the second direction X, the head modules  200  and  200 A can be similarly sized in the second direction regardless of the head unit  10  illustrated in  FIG. 6  or the head unit  10  illustrated in  FIG. 9 . 
     Such head module  200  or head module  200 A as described above is mounted on an ink jet recording apparatus, which is one example of a liquid ejecting apparatus. The ink jet recording apparatus will be hereinbelow described. Incidentally,  FIG. 10  is a schematic cross-sectional view illustrating the ink jet recording apparatus, which is one example of the liquid ejecting apparatus, according to the first embodiment of the invention. 
     According to the first embodiment of the invention, the ink jet recording apparatus, i.e., a so called line-type recording apparatus, to which the head module  200  is secured, performs printing by transporting a recording sheet S, which is a medium to be ejected such as a paper, as illustrated in  FIG. 10 . 
     More specifically, an ink jet recording apparatus  1  includes an apparatus body  2 , the head module  200  secured to the apparatus body  2 , a transporting means  3  for transporting the recording sheet S, i.e. the recording medium to be recorded, and a platen  4  that supports the recording sheet S on a back surface opposite from a printing surface oppositely disposed relative to the head module  200 . 
     The head module  200  is secured to the apparatus body  2  in such manner that the first direction Y, refer to  FIG. 6 , in which the nozzle apertures  26  of the recording heads  20  are disposed side by side, is perpendicular to a transporting direction of the recording sheet S. 
     The transporting means  3  includes a first transporting means  5  and a second transporting means  6  which are disposed on both sides of the transporting direction of the recording sheet S relative to the head module  200 . 
     The first transporting means  5  includes a driving roller  5   a , a driven roller  5   b  and a transporting belt  5   c  wound around the aforementioned driven roller  5   a  and driven roller  5   b . In addition to the above, the second transporting means  6  includes, similarly to the first transporting means  5 , a driving roller  6   a , a driver roller  6   b  and a transporting belt  6   c.    
     The above-mentioned driving rollers  5   a  and  6   a  of the first transporting means  5  and the second transporting means  6  are connected to a driving means such as a driving motor or the like, not illustrated. The recording sheet S is transported at an upper stream side and a down stream side of the head module  200  by rotational driving of the transporting belts  5   c  and  6   c  driven by driving force of the driving means. 
     While the first transporting means  5  and the second transporting means  6 , which include the driving rollers  5   a  and  6   a , the driven rollers  5   b  and  6   b , and the transporting belts  5   c  and  6   c , have been hereinabove exemplified according to the first embodiment of the invention, a holder that holds the recording sheet S on the transporting belts  5   c  and  6   c  may be further provided thereto. As regards the holder, for instance, by providing a charging means that charges the exterior of the recording sheet S, the recording sheet S charged by the charging means may be adsorbed on the transporting belts  5   c  and  6   c  by the effect of dielectric polarization. Further, by providing a pressing roller on the transporting belts  5   c  and  6   c  as the holder, the recording sheet C may be pinched between the pressing roller and the transporting belts  5   c  and  6   c.    
     The platen  4  composed of a metal, a resin or the like is disposed between the first transporting means  5  and the second transporting means  6  in such manner that a cross-sectional surface thereof oppositely disposed relative to the head module  200  is rectangularly shaped. The platen  4  supports the recording sheet C transported by the first transporting means  5  and the second transporting means  6  at an opposite position relative to the head module  200 . 
     Further, the platen  4  may be provided with an adsorbing means that adsorbs the transported recording sheet C on the platen  4 . The adsorbing means includes, e.g., an attracting means that attracts the recording sheet C with attraction force, an electrostatically adsorbing means that adsorbs the recording sheet C with electrostatic action thereto or the like, to name just a few. 
     In addition, an ink container, which is not illustrated, such as the ink container that contains ink therein, an ink cartridge that likewise contains ink therein or the like, is connected to the individual head units  10  of the head module  200  so as to be capable of supplying ink thereto. For instance, the ink container may be retained on the head module  200  or in a different position in the apparatus body  2  from that of the head module  200 , and may be connected to thereto through the ink tube or the like. Each head unit  10  of the head module  200  is further connected to the external wiring, which is not illustrated. 
     As regards the ink jet recording apparatus  1  as described above, the transporting means  5  transports the recording sheet S, and the head module  200  subsequently performs printing on the recording sheet S supported on the platen  4 . The transporting means  3  then transports the printed recording sheet S. 
     Another Embodiment 
     While the first embodiment of the invention has been hereinabove described, it should be understood that the fundamental constitution of the invention is not limited thereto. 
     For instance, the plurality of the head units  10  and the plate-shaped fixing member  210  for fixing the plurality of the head units  10  thereto are provided so as to configure the head module  200  according to the first embodiment of the invention as described above; however, e.g., the cases  60 , which are holders for holding the head units  10  disposed in contiguous relation to each other in the first direction Y, may be fixed together in lieu of the fixing member  210  without being particularly limited thereto. As a matter of course, in a case where something corresponding to the fixing member  210  is provided to the apparatus body  2  of the ink jet recording apparatus  1 , it may thereby negate the need to fix the cases  60  of the head module  200  together. 
     In addition to the above, for instance, the extending portions  63 , which extend outwardly from the case  60  in the rectangular shape, are provided thereto, and the connectors  92  of the circuit substrate  90  are disposed on the extending portions  63  according to the first embodiment as described above; however, there arises the disadvantage of the possibility that the case  60  might be deformed by pushing force or pulling force applied to the portions where the connectors  92  of the circuit substrate  90  are disposed, when the external wirings are connected to the connectors  92  or disconnected therefrom; and, as a result of the above, the deformed case  60  might further result in deformation and misalignment of the recoding heads  20 . As the countermeasures against the above described problems, the extending portions  63 , which are oppositely disposed relative to the connectors  92  of the case  60 , are configured so as to be elastically deformed relative to regions where the recording heads  20  are retained. An another embodiment of the present invention as described above is hereby illustrated in  FIGS. 11A and 11B . Here,  FIGS. 11A and 11B  are cross-sectional views of substantial parts of a head unit according to the another embodiment of the invention. 
     As illustrated in  FIGS. 11A and 11B , a thin wall portion  64  is formed at a boundary between the extending portion  63  oppositely disposed relative to the connector  92  of a case  60 A and a region where the recording head  20  is secured by forming a groove therebetween. A thickness of the boundary between the extending portion  63  and the region where the recording head  20  is secured is reduced by forming the thin wall portion  64 . The stiffness of the boundary between a region where the extending portion  63  is oppositely disposed relative to the connector  92  of the case  60 A and the region where the recording head  20  is secured is reduced by thus providing the thin wall portion  64  to the case  60 A. Hereby, although the portion, where the connector  92  of the circuit substrate  90  is disposed, is elastically deformed by force applied thereto, as illustrated in  FIG. 11B , when the external wiring is connected to the connector  92  or disconnected therefrom, it becomes possible to restrain the region where the recording head  20  of the case  60 A is secured from undergoing deleterious effects of force applied thereto by downwardly displacing only the extending portion  63 . Incidentally, as illustrated in  FIG. 1 , since a wall is upwardly disposed along the inner exterior of the extending portion  63  of the case  60  relative to the ink supply needle  100 , a slit  65  that is continuous with the thin wall  64  can be further provided to the wall; thereby, it becomes possible to deflectively deform only the extending portion  63  of the case  60  with more ease by providing the aforementioned slit  65  thereto. 
     Additionally, the circuit substrate  90  may be arranged so as not to abut against the extending portion  63  of the case  60  when the circuit substrate  90  is elastically deformed. Such an example of the another embodiment of the invention as described above is illustrated in  FIGS. 12A and 12B . Here,  FIGS. 12A and 12B  are cross-sectional views of substantial parts of a head unit according to the another embodiment of the invention. 
     As illustrated in  FIGS. 12A and 12B , a case  60 B is provided with a space formed between an extending portion  63 A and the circuit substrate  90 . As illustrated in  FIG. 12B , the portion of the connector  92  of the circuit substrate  90  is elastically deformed by force applied thereto when the external wiring is connected to the connector  92  or disconnected therefrom; however, such the case  60 B as described above is capable of restraining a region where the recording head  20  of the case  60 B is secured from undergoing deleterious effects of force applied thereto, because the circuit substrate  90  will not abut against the extending portion  63 A due to the space formed between the extending portion  63 A and the circuit substrate  90 . Further, even though the circuit substrate  90  abuts against the extending portion  63 A in consequence of the elastically deformed portion of the connector  92  of the circuit substrate  90 , the aforementioned deleterious effects of force, which are caused by connecting and disconnecting the external wiring to and from the connector  92 , can be suppressed due to a decreased abutting force that is achieved by such the space as described above. It is obvious to those skilled in the art that the thin wall portion  64  illustrated in  FIGS. 11A and 11B  may be combined with the space illustrated in  FIGS. 12A and 12B  as a matter of course. 
     In addition to the above, according to the first embodiment of the invention as described above, the head units  10  are provided with the first projecting portion  11 , the second cut-off portion  14 , the second projecting portion  13  and the first cut-off portion  12  disposed at both ends of the individual head units  10  in the first direction Y. However, without being particularly limited thereto, the first head unit  10 A may be provided with only the first projecting portion  11  and the second cut-off portion  14  at the end opposite to the second head unit  10 B, and the second head unit  10 B may be likewise provided with only the second projecting portion  13  and the first cut-off portion  12  at the end opposite to the first head unit  10 A, in a case where the two head units  10 A and  10 B are disposed side by side in the first direction Y according to the first embodiment of the invention, as described above. In other words, the two head units  10  disposed in contiguous relation to each other may be respectively provided with the projecting portion and the cut-off portion which are disposed at only the ends opposite to each other. Incidentally, cost can be reduced by mass-producing the similarly shaped head units  10  in comparison with manufacturing of differently shaped head units by disposing the first projecting portion  11 , the second cut-off portion  14 , the second projecting portion  13  and the first cut-off portion  12  at both ends of the individual head units  10  as described above. What is more, an arrangement of the head units  10  is not limited thereto, and more than or equal to three head units  10  can be disposed side by side in the first direction Y by disposing the projecting portions and the cut-off portions at both ends of the individual head units  10 . Incidentally, according to the first embodiment of the invention as described above, the projecting portions and the cut-off portions are respectively disposed at both ends of the individual head units  10  in the first direction Y in such manner that both ends of the head units  10 A and  10 B are of rotationally symmetric configuration in the first direction Y; hereby, the two head units  10  can be further disposed in mating relation to each other by rotating the head units  10 , even though a first pair of the first projecting portion  11  and the first cut-off portion  12  is replaced with a second pair of the second projecting portion  13  and the second cut-off portion  14 . However, it is preferable that directions, in which the head units  10  are secured to the fixing member  210 , be unified into one direction regardless of the rotationally symmetric configuration thereof in such a case where the head units  10  are manufactured in consideration of the direction in which the head units  10  are secured to the fixing member  210  or the like when a variation occurs in ejecting characteristics of the recording heads  20  according to manufacturing conditions thereof or the like. 
     Further, according to the first embodiment of the invention as described above, the fluid passage member  80  that includes the main body of the fluid passage member  81  and the cover  82  is exemplified; however, a configuration of the fluid passage member  80  is not particularly limited thereto. For instance, a fluid passage member may be integrally formed with a main body of the fluid passage member and a cover. 
     Further more, according to the embodiments of the invention as described above, thin-film piezoelectric elements are exemplified as pressure generating elements; however, a configuration of pressure generating elements is not particularly limited thereto. For instance, thick-film piezoelectric elements formed by a method of bonding a green sheet thereto or the like, longitudinal vibration piezoelectric elements, which retract and return to an original position in an axial direction by alternately laminating piezoelectric material layers and electrode-forming material layers or the like, may be further used for the pressure generating elements. Still further more, a droplet ejection device that ejects liquid droplets through nozzles thereof by bubbles formed by generated heat of heating elements disposed in a pressure generating chamber, a so-called electrostatic actuator that ejects liquid droplets through nozzles thereof by a vibrating plate deformed by electrostatic force generated between the vibrating plate and an electrode or the like may be further used as the pressure generating elements. 
     In addition to the above, according to the embodiments of the invention as described above, the ink jet recording head has been described as one example of the liquid ejecting head; however, it should be understood that the invention relates to an overall liquid ejecting head module provided with the liquid ejecting head in a broad meaning. The invention, therefore, may be further applicable to the liquid ejecting head modules that includes, e.g., various recording heads used for an image recording apparatus such as a printer or the like, a color material ejecting head used for manufacturing a color filter of a liquid crystal display or the like, an electrode material ejecting head used for forming an electrode of an organic EL display, an FFD, i.e., a field emission display, or the like, and a bioorganic material ejecting head used for manufacturing a bio chip or the like.