Patent Publication Number: US-2016229181-A1

Title: Liquid ejecting head unit and liquid ejecting apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation patent application of U.S. application Ser. No. 14/302,911, filed Jun. 12, 2014, which claims priority to Japanese Patent Application No. 2013-129336, filed Jun. 20, 2013, both applications are expressly incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting head unit that ejects liquid from a nozzle and a liquid ejecting apparatus, and particularly relates to an ink jet recording head unit that discharges ink as liquid and an ink jet recording apparatus. 
     2. Related Art 
     Representative examples of a liquid ejecting head unit that ejects liquid include an ink jet recording head unit that discharges drops of ink. For example, JP-A-2009-6730 proposes an ink jet recording head unit that includes an ink jet recording head, which discharges drops of ink from a nozzle, and a passage member, which is fixed to the ink jet recording head and supplies ink from a liquid reservoir in which the ink is stored, such as an ink cartridge, to a liquid ejecting head. 
     The passage member of the ink jet recording head unit includes an upstream passage member, to which the ink is supplied from the liquid reservoir, and a downstream passage member, which holds the ink jet recording head and supplies the ink from the upstream passage member to the ink jet recording head. The passage member performs hermetic sealing so as to prevent the ink from leaking from a connection passage by causing a sealing member made of a plate-like elastic material, such as a sheet, to be pinched between the upstream passage member and the downstream passage member. 
     However, when it is attempted to hermetically seal the passage in which the upstream passage member and the downstream passage member are connected using the sealing member pinched between two members and made of an elastic material, such as a rubber sheet, repulsion based on elastic deformation of the sealing member may cause pressure to be applied in a direction in which the upstream passage member and the downstream passage member are separated from each other, and pressure may be applied in a direction perpendicular to a liquid ejecting surface that discharges the drops of ink of the liquid ejecting head. As a result, a malfunction may occur, such as separation of the passage member and the liquid ejecting head, separation of a layer member that is a constituent of the liquid ejecting head, or deviation from positions at which the drops of ink are expected to be supplied on an ejected medium, which is caused by warping of the liquid ejecting surface of the liquid ejecting head. 
     In contrast, JP-A-2003-305873 proposes a structure in which two passages are connected through a tube. Although the connection of two passages through a tube may reduce pressure in a direction perpendicular to a liquid ejecting surface, it is necessary to fit the tube to both an upper passage and a lower passage and assembling may be complicated. 
     Besides, in both cases in which the plate-like sealing member is used and the tube-like sealing member is used, it is necessary to press the upstream passage member relatively against the downstream passage member in assembling the upstream passage member and the downstream passage member, and the pressing may cause pressure to be applied in the direction in which the upstream passage member and the downstream passage member are separated from each other. 
     Similar to the ink jet recording head unit, the liquid ejecting head unit that ejects liquid other than ink also has such possibilities. 
     An advantage of some aspects of the invention is to propose a liquid ejecting head unit and a liquid ejecting apparatus, which enable passages to be connected preferably and improve assembility. 
     SUMMARY 
     According to a first aspect of the invention, a liquid ejecting head unit includes a liquid ejecting head that drives a pressure generator and discharges liquid from a nozzle, an upstream passage member with an upstream passage to which liquid is supplied from a liquid retaining portion that retains liquid, a downstream passage member with a downstream passage that communicates with the upstream passage of the upstream passage member and supplies liquid to the liquid ejecting head, a sealing member that connects the upstream passage of the upstream passage member and the downstream passage of the downstream passage member, includes a tubular portion provided inside with a connection passage through which liquid flows, and is made of an elastic material, and a support portion provided between the sealing member and the downstream passage member. In the liquid ejecting head unit, the upstream passage member and the sealing member apply pressure in a penetration direction of the connection passage of the tubular portion and hermetically seal the upstream passage, the sealing member and the downstream passage member apply pressure in a direction perpendicular to the penetration direction of the tubular portion and hermetically seal the downstream passage, and the support portion abuts a region on a side of a surface of the sealing member, the surface being opposite the upstream passage member, the region overlapping a region to which the sealing member and the upstream passage member apply pressure. 
     According to the first aspect, since pressure is applied in the penetration direction of a connection passage due to the hermetic sealing of the upstream passage member and the sealing member, which involves no fitted connection, positioning may easily be performed and assembility may be improved. In addition, since the pressure in the penetration direction may be supported by the support portion, it is possible to suppress application of the pressure in the penetration direction to the liquid ejecting head. Further, since the downstream passage member and the sealing member are hermetically sealed in the direction perpendicular to the penetration direction, it is possible to suppress application of pressure in the penetration direction. 
     According to a second aspect of the invention, a liquid ejecting apparatus includes the liquid ejecting head unit according to the first aspect of the invention. 
     According to the second aspect, it is possible to implement a liquid ejecting apparatus that enables passages to be connected preferably and improves assembility. 
    
    
     
       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 a cross-sectional view of the head unit according to the first embodiment of the invention; 
         FIG. 3  is a cross-sectional view in which a main part of the head unit according to the first embodiment of the invention is enlarged; and 
         FIG. 4  is a perspective view that illustrates a schematic structure of a recording apparatus according to an embodiment of the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The invention is described in detail below based on embodiments. 
     First Embodiment 
       FIG. 1  is an exploded perspective view of an ink jet recording head unit, which is an example of a liquid ejecting head unit according to a first embodiment of the invention. 
       FIG. 2  is a cross-sectional view of the ink jet recording head unit.  FIG. 3  is a cross-sectional view in which a main part of  FIG. 2  is enlarged. 
     As illustrated, an ink jet recording head unit  1 , which is hereinafter also referred to merely as the head unit  1  and is an example of the liquid ejecting head unit according to the present embodiment, includes a plurality of ink jet recording heads  10 , which are hereinafter also referred to merely as the recording heads  10  and discharge drops of ink from nozzles, and a passage member  20 , which holds the plurality of recording heads  10  and is provided with a liquid passage that supplies liquid to the recording heads  10 . 
     The recording head  10  includes a liquid ejecting surface  12  on one side, through which the nozzles that discharges drops of ink as liquid are opened. The liquid ejecting surface  12  of the present embodiment is provided with two nozzle rows that are not particularly illustrated but are arranged in a direction that crosses the direction in which the nozzles are arranged side by side. In the present embodiment, the direction in which the nozzles are arranged side by side in each nozzle row is referred to as a first direction X, and the direction in which the nozzle rows are formed so as to cross the first direction X is referred to as a second direction Y. 
     The inside of the recording head  10 , which is not illustrated, is provided with a passage that communicates with the nozzles and communicates with the liquid passage of the passage member  20 , a pressure generating portion that causes change in pressure for the ink in the passage, and the like. Examples of the pressure generating portion that is usable include a unit that causes drops of ink to be discharged from nozzles by changing the capacity of a passage using deformation of a piezoelectric actuator that contains a piezoelectric material with an electromechanical transduction function and bringing a change in pressure to the ink in the passage, a unit that causes drops of ink to be discharged from nozzles by arranging a heating element in a passage and using bubbles caused by the heat from the heating element, and a so-called electrostatic actuator, which causes drops of ink to be discharged from nozzles by generating electrostatic force between a vibrating plate and an electrode and deforming the vibrating plate using the electrostatic force. 
     A surface of the recording head  10  opposite the liquid ejecting surface  12  is fixed to the passage member  20 , and the ink held in a liquid retaining portion, such as an ink cartridge or an ink tank, is supplied through the passage member  20 . The passage member  20  is provided with the plurality of recording heads  10 . In the present embodiment, the passage member  20  is provided with two rows of the recording heads  10  arranged in the first direction X and in each of the two rows, six of the recording heads  10  are arranged side by side in the second direction Y in which the nozzle rows are formed. That is, a total of  12  nozzle rows are arranged in parallel in the second direction Y in one head unit (the head unit  1 ). Further, in the present embodiment, a direction in which the passage member  20  and the recording heads  10  are fixed is referred to as a third direction Z. That is, the direction in which the passage member  20  and the recording heads  10  are fixed indicates the layer direction and also indicates the direction perpendicular to the plane direction of the liquid ejecting surface  12 , which is an in-plane direction of the first direction X and the second direction Y. 
     The method of fixing the recording heads  10  and the passage member  20  is not particularly limited. For example, the recording heads  10  and the passage member  20  may be bonded by a bonding agent or fixed with screws or the like. Since the recording head  10  is small in size and it is necessary to attach the plurality of recording heads  10  to one passage member, which is the passage member  20 , use of a sealing member made of an elastic material is unsuitable for fixing the recording heads  10  and the passage member  20 . Accordingly, it is preferable to bond the recording heads  10  and the passage member  20  using a bonding agent. 
     The passage member  20  to which the recording heads  10  are fixed includes an upstream passage member  30  provided with an upstream passage  101  to which the liquid retaining portion is connected, a downstream passage member  40  provided with a downstream passage  102  that communicates with the upstream passage  101 , and a sealing member  50  that is provided between the upstream passage member  30  and the downstream passage member  40  and hermetically seals the connection portion of the upstream passage  101  and the downstream passage  102 , and a support member  60  provided with a support portion  61  that supports the sealing member  50 . That is, the liquid passage of the passage member  20  includes the upstream passage  101  and the downstream passage  102 . 
     In the present embodiment, a first upstream passage member  31 , a second upstream passage member  32 , and a third upstream passage member  33  are provided so as to form layers in the third direction Z and make up the upstream passage member  30 . The upstream passage member  30  is not particularly limited to this structure but may be a single member or may be made up of two or more members. The layer direction of the plurality of members that make up the upstream passage member is not particularly limited, either, but may be in the first direction X or the second direction Y. 
     The first upstream passage member  31  is provided with a connection portion  34  on the side of a surface opposite the downstream passage member  40 , and the connection portion  34  is connected to the liquid retaining portion in which the ink (liquid) is held. In the present embodiment, the connection portion  34  projects like a needle, which is connected to the liquid retaining portion. The liquid retaining portion, such as an ink cartridge, may be directly connected to the connection portion  34 , or the liquid retaining portion, such as an ink tank, may be connected to the connection portion  34  through a supply pipe, such as a tube. The inside of the connection portion  34  is provided with a first upstream passage  101   a  through which the ink is supplied from the liquid retaining portion. The downstream side of the first upstream passage  101   a  is provided with a liquid accumulation portion  101   b  with an inner diameter that is largely widened compared to the first upstream passage  101   a  in the connection portion  34 . 
     The second upstream passage member  32  is fixed on the side of a surface of the first upstream passage member  31 , which is opposite the connection portion  34 , and includes a second upstream passage  101 c that communicates with the first upstream passage  101   a . An opening portion of the second upstream passage  101   c  of the second upstream passage member  32  is provided with a filter  35  for removing an air bubble or a foreign substance contained in the ink, and the ink supplied from the first upstream passage  101   a  (the liquid accumulation portion  101   b ) is supplied to the second upstream passage  101   c  through the filter  35 . Depending on the positions of the first upstream passage  101   a  and a third upstream passage  101   d , which is described below, the second upstream passage  101   c  may be any one of a passage that extends in the third direction Z in which the first upstream passage member  31  and the second upstream passage member  32  form layers, a passage that extends in the direction perpendicular to the third direction Z, that is, a passage that extends in a plane including the first direction X and the second direction Y, and the like. 
     The third upstream passage member  33  is provided on a side of the second upstream passage member  32 , which is opposite the first upstream passage member  31 . The third upstream passage member  33  is provided with the third upstream passage  101   d  that communicates with the second upstream passage  101   c  of the second upstream passage member  32 . That is, the upstream passage  101  includes the first upstream passage  101   a , (the liquid accumulation portion  101   b ,) the second upstream passage  101   c , and the third upstream passage  101   d . The third upstream passage  101   d  is opened at one end on the side of the second upstream passage member  32  and communicates with the second upstream passage  101   c . Further, the third upstream passage  101   d  is provided so as to be opened at the other end on the side of the downstream passage member  40 . The cross section of the upstream passage  101  is not limited to a circular shape but may be an elliptic shape, a rectangular shape, or the like. 
     For example, the first upstream passage member  31 , the second upstream passage member  32 , and the third upstream passage member  33 , which include the upstream passage  101 , are integrally arranged in layers using a bonding agent, by welding, or the like. Although the first upstream passage member  31 , the second upstream passage member  32 , and the third upstream passage member  33  may be fixed with screws, clamps, or the like, it is preferable to join the first upstream passage member  31 , the second upstream passage member  32 , and the third upstream passage member  33  with a bonding agent, by welding, or the like so as to suppress leakage of the ink (liquid) from the connection portion from the first upstream passage  101   a  to the third upstream passage  101   d.    
     The third upstream passage member  33  is further provided with a depressed portion  37  that is opened on the side of the downstream passage member  40 . A bottom surface of the depressed portion  37 , that is, the surface on the side of the first upstream passage member  31  is provided with a fixing hole  38  that penetrates in the thickness direction. When a fixing portion  66  provided to the support member  60 , which is described in detail below, so as to project on the side of the upstream passage member  30  is inserted into the depressed portion  37  and a fixing screw  39  is inserted into the fixing hole  38  so as to be threadedly engaged with the fixing portion  66 , the upstream passage member  30  is fixed to one surface of the support member  60 . 
     In the present embodiment, one upstream passage member, which is the upstream passage member  30 , is provided with four connection portions, which are the connection portions  34 , and the one upstream passage member  30  is provided with four independent upstream passages, which are the upstream passages  101 . Although the present embodiment exemplifies a structure in which one upstream passage member (the upstream passage member  30 ) is provided with four independent upstream passages (the upstream passages  101 ), the structure is not particularly limited to this but, for example, the upstream passage  101  may branch into two after passing through the filter  35  from the side of the connection portion  34 . Not to mention, the upstream passage  101  may branch into three after passing through the filter  35 . The one upstream passage member  30  is further provided with two of the fixing holes  38  and is fixed to the support member  60  with the fixing screws  39  at two positions. In the present embodiment, the number of upstream passage members (the upstream passage members  30 ) provided to one head unit (the head unit  1 ) is three. Not to mention, the method of fixing the upstream passage members  30  to the support member  60  is not limited to the fastening with screws but may be, for example, bonding with a bonding agent or the like. In the present embodiment, it is possible to easily attach/detach the upstream passage members  30  to/from the support member  60  by fixing the upstream passage members  30  to the support member  60  with the fixing screws  39 . Accordingly, it is possible to replace only the upstream passage member  30  and improve a yield compared to a case in which the passage member  20  is replaced as a whole. Moreover, since it is possible to easily attach/detach the upstream passage members  30  to/from the support member  60 , reverse cleaning or the like may be easily performed, in which a foreign substance in the upstream passage  101  or on the filter  35  by causing a cleaning liquid to flow backward through the upstream passage  101  of the upstream passage member  30 , or the like. 
     In the support member  60 , the upstream passage members  30  are fixed to one surface in the third direction Z and the downstream passage member  40  is fixed to the other surface. In addition, the sealing member  50 , which serves as a connecting unit that connects the upstream passage  101  of the upstream passage member  30  and the downstream passage  102  of the downstream passage member  40 , is provided between the support member  60  and the upstream passage member  30 . 
     The sealing member  50  has a resistance to liquid, such as the ink used in the head unit  1 , and may be made of an elastically-deformable material (an elastic material), such as a rubber or an elastomer. The sealing member  50  includes a tubular portion  51  for each of the upstream passages  101 . The inside of the tubular portion  51  is provided with a connection passage  103 . In addition, the upstream passage  101  of the upstream passage member  30  and the downstream passage  102  of the downstream passage member  40  are allowed to communicate through the connection passage  103  of the tubular portion  51  as described in detail below. The tubular portion  51  is fitted around the rim of the projecting portion  41  of the downstream passage member  40 , which is described in detail below. Since the projecting portion  41  has a cylindrical shape in the present embodiment, the cross section of the connection passage  103  has a circular shape and a shape in which the thickness is approximately the same along the circumferential direction, that is, the connection passage  103  has a cylindrical shape. A plate-like portion couples the tubular portions  51  on the side of the upstream passage member  30  so that the plurality of tubular portions  51  are integrated with one of the upstream passage members  30 . Since each of the upstream passage members  30  is provided with four upstream passages in the present embodiment, the sealing member  50  that is integrally provided with the four tubular portions  51  is employed. Since in the present embodiment, one passage member (the passage member  20 ) is provided with three upstream passage members (the upstream passage members  30 ), the number of sealing members (the sealing members  50 ) that are provided is the same as the number of upstream passage members (the upstream passage members  30 ), that is, three. 
     The plate-like portion that couples the tubular portions  51  is formed so as to have a thickness that is smaller than the thicknesses of the other regions over the periphery of the tubular portion  51 . Thus, as is described in detail below, when one surface of the sealing member  50  is caused to abut the surface of the upstream passage member  30  through which the upstream passage  101  is opened, only an end surface of the tubular portion  51  abuts the periphery of the opening of the upstream passage  101  and it is possible to increase the pressure for the hermetic sealing by reducing the abutting area and suppress the leakage of the ink (liquid). 
     The connection passage  103  of the tubular portion  51  has an inner diameter approximately the same as the inner diameter of the opening of the upstream passage  101  of the upstream passage member  30 . The tubular portion  51  is formed so as to have an outer diameter that is larger than the inner diameter of the upstream passage  101 . Accordingly, the upstream passage  101  and the connection passage  103  are allowed to communicate by causing the surface of the upstream passage member  30  through which the upstream passage  101  is opened and the end surface of the tubular portion  51  through which the connection passage  103  is opened to abut each other in the penetration direction of the connection passage  103 , that is, in the third direction Z. In other words, the upstream passage  101  and the connection passage  103  are connected in a state in which the upstream passage member  30  and the sealing member  50  are hermetically sealed by applying pressure in the penetration direction of the connection passage  103  (the third direction Z). 
     When the end surface of the tubular portion  51  of the sealing member  50  and the surface of the upstream passage member  30  through which the upstream passage  101  is opened are caused to abut each other with predetermined pressure in the third direction Z, the tubular portion  51  of the sealing member  50  is elastically deformed toward the recording head  10  in the third direction Z. Thus, the support member  60  is provided with the support portion  61  so as to abut the other end surface of the tubular portion  51  of the sealing member  50 , which is opposite the end surface that abuts the upstream passage member  30 , and support the tubular portion  51  in the third direction Z. 
     Specifically, the inside of the support portion  61  is provided with a tubular portion insertion hole  62 , which has a tubular shape and in which the tubular portion  51  of the sealing member  50  is inserted on the side of the upstream passage member  30 , and a projecting portion insertion hole  63 , in which the projecting portion  41  of the downstream passage member  40  is inserted on the side of the downstream passage member  40 . 
     The tubular portion insertion hole  62  has an inner diameter larger than the outer diameter of the tubular portion  51  and is formed so that the tubular portion  51  may easily be inserted/extracted from one side. 
     The projecting portion insertion hole  63  has an inner diameter that is slightly larger than the outer diameter of the projecting portion  41  of the downstream passage member  40  and smaller than the outer diameter of the tubular portion  51  of the sealing member  50 . Thus, a level difference  64 , which is caused by the difference in inner diameter, is formed inside the support portion  61  and between the tubular portion insertion hole  62  and the projecting portion insertion hole  63 . 
     When the tubular portion  51  of the sealing member  50  is inserted in the tubular portion insertion hole  62  of the support portion  61 , the end surface of the tubular portion  51 , which is the other end surface opposite the end surface that abuts the upstream passage member  30 , abuts the level difference  64  and as a result, a move in the insertion direction (the third direction Z) may be suppressed. That is, in the present embodiment, one end surface of the tubular portion  51  of the sealing member  50  abuts the upstream passage member  30  and the connection portion of the upstream passage  101  and the connection passage  103  is hermetically sealed, and the other end surface of the tubular portion  51  abuts the level difference  64  of the support portion  61  to be supported. Thus, since the upstream passage member  30  is fixed to the support member  60 , even when the tubular portion  51  of the sealing member  50  is pressed toward the downstream passage member  40 , the repulsion caused by the elastic deformation of the sealing member  50  is supported by the support portion  61  of the support member  60 . As a result, no repulsion of the sealing member  50  is applied toward the downstream passage member  40 , and the upstream passage member  30  and the sealing member  50  abut each other while being pressed with predetermined pressure. 
     Since one end surface of the tubular portion  51  abuts the upstream passage member  30  and the other end surface abuts the level difference  64  of the support portion  61  in this manner, the support portion  61  (the level difference  64 ) abuts a region to which the sealing member  50  (the tubular portion  51 ) on the side opposite the surface that abuts the upstream passage member  30  and the upstream passage member  30  apply pressure, that is, a position that overlaps the region in which the upstream passage member  30  and the sealing member  50  abut each other and perform the hermetic sealing. That the support portion  61  (the level difference  64 ) abuts a position that overlaps the region to which the sealing member  50  (the tubular portion  51 ) and the upstream passage member  30  apply pressure is rephrased as follows: when projection is performed in the third direction Z on the region in which the upstream passage member  30  and the tubular portion  51  of the sealing member  50  abut each other and on the region supported by the support portion  61  (the level difference  64 ) and the sealing member  50  abutting each other, the positions of the regions overlap each other. Since the tubular portion  51  pressed by the upstream passage member  30  is supported by the support portion  61  on an axis in the third direction Z in this manner, it is possible to suppress occurrence of deformation of the tubular portion  51 , such as distortion in the first direction X or the second direction Y. If the region in which the upstream passage member  30  presses the tubular portion  51  and the region that the support portion  61  supports (the region that the level difference  64  abuts) are positioned so as not to overlap each other when undergoing the projection in the third direction Z, the tubular portion  51  may be distorted and deformed in the first direction X and the second direction Y and as a result, the ink (liquid) may leak from the connection portion of the upstream passage  101  and the connection passage  103  or the connection portion of the connection passage  103  and the downstream passage  102 . In the present embodiment, the region in which the upstream passage member  30  and the tubular portion  51  of the sealing member  50  abut each other and the region supported by the support portion  61  (the level difference  64 ) and the tubular portion  51  of the sealing member  50  that abut each other are positioned so as to overlap each other when undergoing the projection in the third direction Z. Thus, it is possible to suppress distortion and deformation of the tubular portion  51  and suppress leakage of the ink in the connection portion of each passage. 
     The downstream passage member  40  is fixed on the side of a surface of the support member  60 , which is opposite the upstream passage member  30 . The recording head  10  is fixed on the side of a surface of the downstream passage member  40 , which is opposite the support member  60 . 
     The downstream passage member  40  is provided with the downstream passage  102  that communicates with the upstream passage  101  of the upstream passage member  30 . The downstream passage  102  is provided so as to be opened at one end through the surface to which the recording head  10  is fixed and be opened at the other end through the top end surface of the projecting portion  41  that is tubular and is provided so as to project on the side of the upstream passage member  30 . 
     As described above, the projecting portion  41  has an outer diameter that is slightly smaller than the inner diameter of the projecting portion insertion hole  63  of the support portion  61 , and is inserted in the projecting portion insertion hole  63  of the support portion  61 . The tubular portion  51  of the sealing member  50  inserted in the tubular portion insertion hole  62  is fitted around the rim of the projecting portion  41  inserted in the projecting portion insertion hole  63  and thus, the downstream passage  102  and the connection passage  103  of the tubular portion  51  are connected. Accordingly, the upstream passage  101  and the downstream passage  102  are connected (linked together) through the connection passage  103 . The inner diameter of the connection passage  103  is slightly smaller than the outer diameter of the projecting portion  41 , and when the sealing member  50  (the tubular portion  51 ) is elastically deformed so as to widen the inner diameter, the inner surface of the connection passage  103  comes into intimate contact with the outer circumferential surface of the projecting portion  41  in a state in which pressure is applied in the directions perpendicular to the penetration direction of the connection passage  103  (the third direction Z), that is, in the first direction X and the second direction Y. In other words, the upstream passage  101  and the connection passage  103  are hermetically sealed in a state in which pressure is applied in the radial direction of the connection portion (the connection passage  103 ). The radial direction of the connection portion of the upstream passage  101  and the downstream passage  102  (the radial direction of the connection passage  103 ) is in the direction that crosses the direction in which the ink passes (the penetration direction through the connection passage  103 ), and is, in the present embodiment, in the plane direction including the first direction X and the second direction Y. Although the upstream passage  101  and the downstream passage  102  are provided so that the ink flows along the third direction Z in the present embodiment, the structure is not particularly limited to this but any one or both of the upstream passage  101  and the downstream passage  102  may be provided in the direction that crosses the third direction Z. In this case, the radial direction of the upstream passage  101  and the downstream passage  102  is in the direction that crosses the plane direction including the first direction X and the second direction Y. 
     In this manner, the sealing member  50  (the tubular portion  51 ) that hermetically seals the connection portion of the downstream passage  102  of the downstream passage member  40  applies pressure in the radial direction of the downstream passage  102 , that is, in the direction perpendicular to the third direction Z to perform the hermetic sealing. As a result, the sealing member  50  is elastically deformed in the direction perpendicular to the plane direction of the liquid ejecting surface  12 , that is, in the third direction Z and the repulsion may suppress a press against the recording head  10 . Accordingly, it is possible to suppress separation of the recording head  10  from the passage member  20 , separation of a layer member arranged in layers in the third direction Z, which is not illustrated but is a constituent of the recording head  10 , and occurrence of warping on the liquid ejecting surface  12  of the recording head  10 , and it is possible to suppress deviation from the positions at which the drops of ink are expected to be supplied from the nozzles to an ejected medium, which may be caused by the warping of the liquid ejecting surface  12 . 
     As described above, the sealing member  50  that hermetically seals the connection portion of the upstream passage  101  of the upstream passage member  30  applies pressure in the direction in which the ink flows through the upstream passage  101 , that is, in the third direction Z to perform the hermetic sealing. However, since in the present embodiment, the support portion  61  is caused to support the region in which the upstream passage member  30  of the sealing member  50  presses the sealing member  50  in the third direction Z, the pressure with which the upstream passage member  30  presses the sealing member  50  in the third direction Z is supported by the support portion  61 . The support member  60  that has the support portion  61  is fixed in a region in which the support member  60  does not overlap the downstream passage member  40  or the nozzles when undergoing projection. Thus, the pressure with which the upstream passage member  30  presses the sealing member  50 , which is the repulsion caused by the elastic deformation, is supported by the support portion  61  and dispersed to a fixing region in which the support member  60  that has the support portion  61  and the downstream passage member  40  are fixed. Accordingly, it is possible to suppress application of the pressure against the sealing member  50  particularly to the periphery of the nozzles of the recording head  10 . As a result, it is possible to suppress separation of a member that is a constituent of the recording head  10 , separation of the passage member  20  and the recording head  10 , deviation from the positions at which the drops of ink are expected to be supplied, which is caused by the warping of the liquid ejecting surface of the recording head  10 , and the like. 
     Further, when the upstream passage member  30  and the sealing member  50  are connected while applying pressure in the direction in which the ink flows, that is, in the third direction Z, relative positioning and connection of the upstream passage member  30  and the sealing member  50  may be performed easily. If the upstream passage  101  is provided in a projecting portion shaped like a cylinder, similar to the downstream passage  102 , and the tubular portion  51  of the sealing member  50  is fitted around the rim of the projecting portion so as to connect the upstream passage  101  and the connection passage  103 , the plurality of projecting portions need to be inserted in the tubular portions  51  of the sealing member  50  at the same time and workability decreases. Particularly, it is difficult to visually check the connection portion of the upstream passage member  30  and the sealing member  50  because the support member  60  or the like hides the connection portion and thus, it may be impossible to check the accuracy of the connection. Besides, when an error occurs between the positions of the plurality of projecting portions and the positions of the plurality of tubular portions  51 , the tubular portion  51  needs to be bent and a malfunction, such as leakage of the ink, may be caused by the poor sealing. Since in the present embodiment, the plane of the upstream passage member  30  and the plane of the sealing member  50  are caused to abut each other in the third direction Z, pressure is applied in the third direction Z, and the upstream passage  101  and the connection passage  103  are allowed to communicate, the positioning may be performed easily without any visual check. In addition, even when an error occurs at the position of each of the tubular portions  51  relative to the plurality of upstream passages  101 , it is possible to reduce application of force in the direction in which the tubular portion  51  is bent and suppress leakage of the ink caused by the poor sealing. 
     In a method of manufacturing the head unit  1  described above, the downstream passage member  40  and the support member  60  are fixed first, and then the tubular portion  51  of the sealing member  50  is fitted around the projecting portion  41  provided with the downstream passage  102 . After that, the upstream passage member  30  is positioned so that the opening of the upstream passage  101  matches the tubular portion  51  of the sealing member  50  (the opening of the connection passage  103 ), and the upstream passage member  30  is fixed to the support member  60 . Thus, poor sealing of the upstream passage  101 , the connection passage  103 , and the downstream passage  102  may be suppressed while performing positioning and assembling easily. Although the connection passage  103  and the downstream passage  102  may be connected after the upstream passage  101  and the connection passage  103  have been connected, as described above, it is difficult and not preferable to cause the tubular portions  51  to be fitted around the plurality of projecting portions  41  without performing visual check. 
     In the present embodiment, further, a wiring substrate  70  is provided between the downstream passage member and the support member  60 . The wiring substrate  70  is provided with wiring that is not particularly illustrated but is connected to a pressure generating portion provided to the recording head  10 , or the like. The wiring substrate  70  is further provided with a connector  71 , and external wiring into which a wiring connection hole  65  provided to the support member  60  penetrates, which is not illustrated, is connected to the connector  71 . When the wiring substrate  70  is provided in the passage member  20  in this manner, the wiring may suffer a short circuit if the wiring substrate  70  comes into contact with the ink. Thus, it is necessary to suppress particularly the leakage of the ink (liquid) from the connection portion of the upstream passage  101  and the downstream passage  102 . Since in the present embodiment, the connection portion of the upstream passage  101  and the downstream passage  102  is sealed using the sealing member  50  and the support portion  61  is provided, the connection portion of the upstream passage  101  and the downstream passage  102  may be hermetically sealed with high pressure while suppressing the application of the pressure in the third direction Z to the recording head  10 . Accordingly, leakage of the ink may be suppressed and occurrence of a malfunction, such as a short circuit of the wiring, may be suppressed. Another Embodiment 
     Although one embodiment of the invention is described above, the basic structure of the invention is not limited to the above-described structures. 
     For example, although the first embodiment described above exemplifies the sealing member  50  that is integrally provided with the plurality of tubular portions  51 , the structure is not particularly limited to this but the tubular portion  51  may be an independent tubular portion for each of the upstream passages  101 . 
     Further, although in the first embodiment described above, the upstream passage member  30  is made up of three members, which are the first upstream passage member  31 , the second upstream passage member  32 , and the third upstream passage member  33 , the upstream passage member  30  may be a single member or may be made up of a plurality of members, the number of which is a number other than three. Similarly, although in the above-described example, the downstream passage member  40  is a single member, the structure is not particularly limited to this but the downstream passage member  40  may be made up of two or more members. 
     Although the support portion  61  is provided to the support member  60  in the first embodiment described above, the structure is not particularly limited to this but the support portion  61  may be provided as part of the downstream passage member  40  or the upstream passage member  30 . When, for example, the support portion  61  is integrally provided to the downstream passage member  40 , similar to the first embodiment described above, it is satisfactory for the support portion  61 , which includes the support portion  61  integrally formed and supported, to be fixed to the downstream passage member  40  at a position that does not overlap the nozzles of the recording head  10  when undergoing projection in the third direction Z. 
     Moreover, although the first embodiment described above exemplifies the support portion  61  that has a cylindrical shape, the support portion  61  is not particularly limited to the structure but may be provided to the tubular portion  51  non-continuously in the circumferential direction because it is satisfactory for the support portion  61  to abut an end surface of the tubular portion  51  so that a move of the tubular portion  51  in the third direction Z is restricted. That is, the support portion  61  may be provided with slits or the like at predetermined gaps in the circumferential direction. 
     Further, although the first embodiment described above exemplifies the passage member  20  that includes the upstream passage member  30  provided with the upstream passage  101  and the downstream passage member  40  provided with the downstream passage  102 , when for example, the ink (liquid) is caused to circulate, the upstream side and the downstream side may be reversed. That is, the ink supplied to the recording head  10  may be caused to flow from the downstream passage  102  to the upstream passage  101  to be discharged (circulate) to the liquid retaining portion, a reservoir in which the discharged ink is stored, or the like. 
     The head unit  1  according to the first embodiment described above is mounted in an ink jet recording apparatus.  FIG. 4  is a schematic view that illustrates an example of the ink jet recording apparatus. 
     In an ink jet recording apparatus I illustrated in  FIG. 4 , an ink cartridge  2  that serves as the liquid retaining portion is provided to the head unit  1  so as to be attachable/detachable. The head unit  1  provided with the ink cartridge  2  is mounted on a carriage  3 . The carriage  3  is provided to a carriage axis  5  attached to an apparatus body  4  so as to be movable in the axis direction. 
     When driving force of a drive motor  6  is transferred to the carriage  3  through a plurality of gear wheels, which are not illustrated, and a timing belt  7 , the carriage  3  with the head unit  1  is moved along the carriage axis  5 . The apparatus body  4  is provided with a platen  8  along the carriage axis  5 , and a recording sheet S fed as a recording medium by a paper feeding roller not illustrated, such as paper, is wound around the platen  8  to be transported. 
     Although in the above-described ink jet recording apparatus I exemplified, the head unit  1  is mounted on the carriage  3  and moved in the main scanning direction, the structure is not particularly limited to this but the invention may be applied to, for example, a so-called line recording apparatus in which the head unit  1  is fixed and printing is performed only by moving the recording sheet S, such as paper, in the subscanning direction. 
     Although the above-described example exemplifies the ink cartridge  2  as the liquid retaining portion, the liquid retaining portion is not particularly limited to an ink cartridge but, for example, an ink tank or the like may be fixed as the liquid retaining portion to the apparatus body  4 , and the liquid retaining portion and the head unit  1  may be connected through a supply pipe, such as a tube. That is, the head unit  1  is not limited to the structure in which the liquid retaining portion is directly connected to the connection portion  34  but the liquid retaining portion may be connected to the connection portion  34  through a supply pipe or the like. It is optional to mount the liquid retaining portion in the ink jet recording apparatus I. 
     The invention is largely aimed at liquid ejecting heads in general and may be applied to, for example, a recording head included in various kinds of ink jet recording heads used in image recording apparatuses, such as printers, a coloring material ejecting head used to manufacture a color filter for a liquid crystal display or the like, an electrode material ejecting head used to form an electrode for an organic electroluminescent (EL) display, a field emission display (FED), or the like, or a bioorganic substance ejecting head used to manufacture a biochip.