Patent Publication Number: US-9844941-B2

Title: Liquid ejecting head and liquid ejecting apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting head, such as an ink jet type recording head, and a liquid ejecting apparatus that includes the liquid ejecting head. More particularly, the invention relates to a liquid ejecting head that includes a flow path member in which a plurality of flow path component members are stacked and to a liquid ejecting apparatus that includes the liquid ejecting head. 
     2. Related Art 
     A liquid ejecting apparatus is an apparatus that is equipped with a liquid ejecting head and that ejects (discharges) various liquids from the ejecting head. Examples of the existing liquid ejecting apparatus are image recording apparatuses such as ink jet type printers and ink jet type plotters. In recent years, the liquid ejecting apparatus is applied to various production apparatuses by utilizing the advantage of being capable of accurately landing very small amounts of liquid at predetermined locations. Examples of such applications include a display production apparatus that produces a color filter of a liquid crystal display and the like, an electrode forming apparatus that forms electrodes of organic electro-luminescence (EL) displays, field emission displays (flat panel displays), etc., and chip production apparatuses that produce biochips (biochemical devices). The recording head for an image recording apparatus ejects an ink in a liquid state, and the color material ejecting head for a display production apparatus ejects solutions of color materials of red (R), green (G), and blue (B). Furthermore, the electrode material ejecting head for an electrode forming apparatus ejects an electrode material in a liquid state, and the bioorganic material ejecting head for a chip production apparatus ejects a solution of a bioorganic material. 
     The liquid ejecting head introduces a liquid from a liquid supply source in which the liquid is stored, and ejects the liquid in the form of droplets from the nozzles by driving drive elements such as piezoelectric elements, heating elements, etc. A certain liquid ejecting head includes liquid flow paths constructed of a plurality of stacked component parts. For example, in a liquid ejecting head described in JP-A-2015-051623, flow path members that include a first flow path member, a filter, and a second flow path member are housed within an upper/lower case member that includes an upper case member and a lower case member. Furthermore, a seal member (bush) made of an elastic material is provided between a lower case member and a flow path portion that includes the upper case member and a flow path member. This seal member provides liquid-tight communication between a flow path of a flow path portion side and a flow path of a lower case member side via a through opening of the seal member. In this construction, the seal member is provided with an atmospherically open path that provides communication between a space on an inner periphery side of the seal member and the atmosphere on an outer periphery side of the seal member. Therefore, a space on a lower side of the seal member and a space formed between the seal member and the flow path portion are open to the atmosphere through the atmospherically open path. This atmospherically open path is formed by a thin groove formed on an upper surface of an annular seal site of the seal member and the flow path member in close contact with the upper surface of the annular seal site. 
     In the foregoing construction, the upper case member is merely fixed to the lower case member by performing, for example, screwing or crimping, from a lower portion of the case. Therefore, gas tightness and liquid tightness of the interior of the upper/lower case member are not secured. Furthermore, because a common elastomer used for the seal member is not an elastomer enhanced in gas barrier property, moisture (a solvent component) in a liquid flow path passes in the form of vapor through the material of the seal member in addition to the foregoing atmospherically open path and diffuses into the atmosphere. Therefore, there is a problem that the thickening (viscosity increase) of the liquid in the liquid flow path of the flow path member in particular progresses. 
     SUMMARY 
     An advantage of some aspects of the invention is that a liquid ejecting head and a liquid ejecting apparatus that are capable of inhibiting the thickening of a liquid in a liquid flow path of a flow path member are provided. 
     A liquid ejecting head according to one aspect of the invention includes a first case that houses a flow path member that is provided with a liquid flow path, a second case that includes a head unit, a seal member that includes a connecting portion that seals and liquid-tightly connects the liquid flow path on a first case side and a liquid flow path on a second case side. The liquid ejecting head ejects a liquid supplied from the flow path member from a nozzle of the head unit. A flow path-isolating member having higher gas barrier property than the seal member is disposed between the first case and the seal member. The flow path member is disposed in a sealed space that is defined in the first case by a flow path-isolating member being joined to the first case. 
     According to this aspect of the invention, because the flow path member is disposed in the sealed space that is defined in the first case as the flow path-isolating member having high gas barrier property is joined to the first case, evaporation of moisture (a solvent component) of the liquid in the liquid flow path of the flow path member disposed in the sealed space is inhibited. This inhibits the thickening of the liquid present in the liquid flow path of the flow path member. 
     In the foregoing construction, the first case may have higher gas barrier property than the seal member. 
     According to this construction, because the sealed space is defined as the flow path-isolating member is joined to the first case having higher gas barrier property than the seal member, evaporation of moisture of the liquid in the liquid flow path of the flow path member disposed in the sealed space is inhibited more surely. 
     In the foregoing construction, the seal member may have an outside wall along an outer perimeter of the seal member, and a space in which the connecting portion is disposed may be sealed by placing the outside wall in close contact with the flow path-isolating member and a component member on the second case side. 
     According to this construction, because the space in which the connecting portion is disposed is sealed as the seal member outside wall is in close contact with the flow path-isolating member and the second case-side component member, that is, because the connecting portion between the first case-side liquid flow path and the second case-side liquid flow path is double-sealed, moisture (a solvent) of the liquid in the liquid flow path is inhibited from evaporating from the connecting portion between the first case-side liquid flow path and the second case-side liquid flow path. 
     In the foregoing construction, a portion of the flow path-isolating member which contacts the outside wall of the seal member may be provided with a groove extending along the outer perimeter, and a resistance pathway may be formed by the portion having contact with the outside wall. The resistance pathway may communicate with the sealed space and also communicate with an atmospherically open path that connects to an atmosphere. 
     According to this construction, because the resistance pathway both restrains moisture evaporation from the liquid flow path in the sealed space (maintains a high-humidity state) and allows the sealed space to be open to the atmosphere, pressure changes in the sealed space can be reduced. 
     In the foregoing construction, the first case may include a positioning pin that defines a position at which the flow path member is disposed. The flow path member may have an insertion hole into which the positioning pin is inserted. The flow path-isolating member may have a recess portion into which a distal end portion of the positioning pin fits. The positioning pin may be covered by the flow path member and the flow path-isolating member and disposed in the sealed space by inserting the positioning pin through the insertion hole and fitting the positioning pin into the recess portion. 
     According to this construction, because the positioning pin is disposed in the sealed space in a state in which the positioning pin is covered by the flow path member and the flow path-isolating member by inserting the positioning pin into the insertion hole and fitting it into the recess portion, the sealed space is prevented from communicating with the atmosphere via the insertion hole in which the positioning pin is inserted, so that it becomes possible to position the flow path member and the flow path-isolating member by the positioning pin while securing gas tightness and liquid tightness of the sealed space. 
     Furthermore, in the foregoing construction, the first case may have a positioning pin that defines a position at which the flow path member is disposed. The flow path member and the flow path-isolating member may each have an insertion hole into which the positioning pin is inserted. The positioning pin may be inserted in the insertion hole and disposed in the sealed space, and a distal end portion of the positioning pin exposed via the insertion hole may be sealed by a sealer. 
     According to this construction, because the positioning pin is disposed in the sealed space in a state in which the positioning pin is inserted in the insertion hole and the distal end portion exposed via the insertion hole is sealed by the sealer, the sealed space is prevented from communicating with the atmosphere via the insertion holes in which the positioning pin is inserted, so that it becomes possible to position the flow path member and the flow path-isolating member by the positioning pin while securing gas tightness and liquid tightness of the sealed space. 
     In the foregoing construction, the flow path member may be formed by stacking a plurality of flow path component members. One of the flow path component members may be the flow path-isolating member. 
     According to this construction, because one of the flow path component members is a flow path-isolating member, it is unnecessary to provide a flow path-isolating member separately from the flow path component members that constitute the flow path member and therefore it becomes possible to reduce the size of the liquid ejecting head. The material cost can also be reduced. 
     A liquid ejecting apparatus according to another aspect of the invention includes a liquid ejecting head having any one of the foregoing construction. 
     According to this liquid ejecting apparatus, because the thickening of liquid in the flow path member is inhibited, changes in ink ejection characteristics, such as the weight of liquid ejected from the nozzle and the flying speed of ejected liquid, caused by the thickening of liquid are inhibited. Therefore, the reliability of the liquid ejecting apparatus improves. Furthermore, it becomes possible to reduce the amount of liquid consumed in a maintenance operation of discharging thickened liquid from the nozzle by performing liquid suction while having a nozzle surface of the liquid ejecting head sealed by a cap. 
    
    
     
       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 a perspective view illustrating a construction of a liquid ejecting apparatus (printer). 
         FIG. 2  is an exploded perspective view of a liquid ejecting head (recording head). 
         FIG. 3  is a sectional view of the liquid ejecting head. 
         FIG. 4  is a sectional view of a positioning pin and its surroundings. 
         FIG. 5  is a bottom plan view of a second flow path member. 
         FIG. 6  is a sectional view taken along line VI-VI in  FIG. 5 . 
         FIG. 7  is a sectional view taken along line VII-VII in  FIG. 5 . 
         FIG. 8  is a sectional view illustrating an atmospherically open passageway of a first case and of flow path members. 
         FIG. 9  is a sectional view of a head unit. 
         FIG. 10  is a sectional view of a positioning pin and its surroundings in a second exemplary embodiment of the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments of the invention will be described hereinafter with reference to the accompanying drawing. Although the exemplary embodiments described below are limited in various manners as preferred concrete examples of the invention, the scope of the invention is not limited to such various manners and forms unless it is mentioned in the following description that the invention is limited in a particularly manner. Furthermore, in the following description, the liquid ejecting apparatus of the invention will be described in conjunction with an example of an ink jet type printer (hereinafter, referred to simply as printer  1 ) that includes an ink jet type recording head (hereinafter, referred to simply as recording head  3 ) that is a type of liquid ejecting head. 
     First, a construction of the printer  1  according to an exemplary embodiment of the invention will be described with reference to  FIG. 1 . The printer  1  is an apparatus that performs recording of an image or the like by ejecting an ink in a liquid state onto a surface of a recording medium  2  such as a recording sheet or the like. This printer  1  includes a recording head  3 , a carriage  4  on which the recording head  3  is mounted, and a carriage moving mechanism  5  that moves the carriage  4  in a main scanning direction. Furthermore, the printer  1  includes a transporting mechanism that transports the recording medium  2  in a subsidiary scanning direction. Note that the foregoing ink is a kind of liquid in the invention and is stored in an ink cartridge  7  as a liquid supply source or a liquid storing container. This ink cartridge  7  is detachably fitted to the recording head  3 . It is also possible to adopt a construction in which an ink cartridge  7  is disposed on a main body of the printer  1  and the ink in the ink cartridge  7  is supplied to the recording head  3  through an ink supply tube. 
     In the printer  1 , a home position that is a standby position of the carriage  4  is set on an end side of the carriage  4  in the main scanning direction. A capping mechanism  6  (a kind of a maintenance mechanism) is disposed at the home position. The capping mechanism  6  includes a tray shaped cap  6 ′ (sealing member) that can contact a nozzle surface that is provided with nozzles  75  (see  FIG. 9 ) of the recording head  3 . This capping mechanism  6  is constructed so that an opening formed on an upper surface side of the cap  6 ′ will face the nozzles  75  of the recording head  3  when the cap  6 ′ has close contact with the nozzle surface. By making the sealed state in which the cap  6 ′ is in close contact with the nozzle surface, a sealed cavity is defined in the cap  6 ′. A pump unit (not graphically shown) is connected to the cap  6 ′. The pump unit includes a suction pump, for example, a tube pump or the like, and is capable of producing negative pressure in the sealed cavity by operating the suction pump. When, during the state of close contact with the nozzle surface, the suction pump is operated to produce negative pressure in the sealed cavity (enclosed space), ink and air bubbles in the recording head  3  are sucked out through the nozzles  75  and discharged into the sealed cavity of the cap  6 ′. That is, this capping mechanism  6  performs a cleaning operation that is a kind of maintenance operation of forcing air bubbles or thickened ink to be sucked and discharged out of the ink flow path of the recording head  3 . 
       FIG. 2  is an exploded perspective view showing a construction of the recording head  3 .  FIG. 3  is a sectional view of the recording head  3 . In the following description, the nozzle surface of the recording head  3  is used as a reference surface and the direction orthogonal to the nozzle surface is assumed to be an up-down direction. In this exemplary embodiment, the recording head  3  includes a first case  10  on an upper side and a second case  11  on a lower side. Inside the first case  10  and the second case  11 , a flow path member  9 , a seal member  18 , a circuit board  17 , a flow path-connecting member  19 , a plurality of head units  13 , etc. are stacked and houses. Furthermore, the flow path member  9  is made up by stacking a plurality of flow path component members, concretely, a first flow path member  14 , a filter substrate  16 , and a second flow path member  15 . The first case  10  and the second case  11 , housing therein the foregoing component members, are fixed to each other by, for example, a fastening member  30  such as a screw, a crimp pin, etc. 
     The first case  10  is a member from which a plurality of introduction pins  22  stand. The first case  10  is produced from, for example, a synthetic resin whose gas barrier property has been enhanced as compared with the seal member  18 , such as a modified polyphenylene ether containing a glass filler (modified PPE: ZYLON (registered trademark)) or the like. Furthermore, in this exemplary embodiment, the various flow path component members (the first flow path member  14 , the filter substrate  16 , and the second flow path member  15 ) that constitute the flow path member  9  are also each manufactured from a synthetic resin having an enhanced gas barrier property compared to the seal member  18 . Incidentally, it suffices that, of the flow path component members of the flow path member  9 , the second flow path member  15  is manufactured from a synthetic resin having an enhanced gas barrier property compared to the seal member  18 , and the other flow path component members do not necessarily need to be made of a synthetic resin having an enhanced gas barrier property. 
     In this exemplary embodiment, a total of four introduction pins  22  corresponding to the different color inks of ink cartridges  7  are provided side by side along the scanning direction of the recording head  3  on an upper surface of an introduction pin baseboard  21  of the first case  10 . These introduction pins  22  are hollow needle-shaped members that are inserted into the ink cartridges  7  so as to introduce the inks stored in the ink cartridges  7  to a first flow path member  14  side through internal needle flow paths (not graphically shown). Incidentally, the construction for introducing the inks from the ink cartridges  7  into the recording head  3  is not limited to one that employs introduction pins  22  but may also be, for example, a construction in which, for each ink, the ink supply side and the ink reception side are each provided with a porous member capable of absorbing the ink and the porous members are placed in contact with each other to supply and receive the ink. 
     Furthermore, as shown in  FIG. 3 , as for the first case  10  in this exemplary embodiment, four-side edges of the introduction pin baseboard  21  are provided with side walls  23  that extend downward (to the second case  11  side). In a space enclosed by the side walls  23  and the introduction pin baseboard  21 , the first flow path member  14  and the filter substrate  16 , of the aforementioned flow path component members of the flow path member  9 , are housed. The second flow path member  15  (a kind of a flow path-isolating member in the invention) is joined by an adhesive to lower ends of the side walls  23  so as to close a lower surface-side opening of the space in which the first flow path member  14  and the filter substrate  16  are housed. This adhesive is one that is capable of securing gas and liquid tightness of the joining portions, for example, an epoxy-based adhesive. Thus, the first case  10  and the second flow path member  15  define a sealed space  12  that is isolated from external air. Therefore, liquid flow paths within the flow path member  9  (series of flow paths that include guide flow paths  31 , filter chambers  24 , and supply flow paths  33  which will be described below) are housed in the sealed space  12 . This sealed space  12  functions as a moisture evaporation management space that inhibits moisture that has penetrated through portions of wall surfaces that form internal liquid flow paths from excessively evaporating from the internal liquid flow paths. Incidentally, the sealed space  12  is not a completely tightly closed space but is open to the atmosphere through an atmospherically open passageway that will be described later. A resistance pathway that forms a portion of the atmospherically open passageway inhibits evaporation of moisture from the flow paths while allowing the sealed space  12  to be open to the atmosphere. This will be described later. 
       FIG. 4  is a sectional view of a positioning pin  26  and its surroundings. A plurality of positioning pins  26  are protruded downward (to the second case  11  side) from a lower surface of the introduction pin baseboard  21  of the first case  10 . These positioning pins  26  define the relative position of the flow path member  9  in directions orthogonal to the stacking direction of the flow path component members of the flow path member  9 . Correspondingly, the first flow path member  14  is provided with positioning holes  27  (corresponding to an insertion hole in the invention) which penetrate through the first flow path member  14  in its plate thickness direction and through which the positioning pins  26  can be inserted. Likewise, the filter substrate  16  is also provided with positioning holes  28  (corresponding to an insertion hole in the invention) which penetrates through the filter substrate  16  in its plate thickness direction and through which the positioning pins  26  can be inserted. On the other hand, the second flow path member  15  in this exemplary embodiment is provided with positioning recess portions  29  (corresponding to a recess portion in the invention) into which distal end portions of the positioning pins  26  can be fitted. That is, the positioning recess portions  29  extend in a hollow shape from positions on an upper surface (first case  10 -side surface) of the second flow path member  15  which correspond to the positions of the distal end portions of the positioning pins  26  toward a lower surface (second case  11 -side surface) of the second flow path member  15  in the thickness direction of the second flow path member  15  without penetrating through the second flow path member  15 . As the first flow path member  14 , when the filter substrate  16 , and the second flow path member  15  are stacked in a state in which the positioning pins  26  are inserted through the positioning holes  27  and  28  of the first flow path member  14  and the filter substrate  16  and their distal end portions are fitted into the positioning recess portions  29  of the second flow path member  15 , the relative positions of these flow path component members are fixed. The positioning pins  26  are disposed in the sealed space  12 , in a state in which the positioning pins  26  are covered by the first flow path member  14 , the filter substrate  16 , and the second flow path member  15 . Therefore, communication of the sealed space  12  with the atmosphere through the positioning holes  27  and  28  into which the positioning pins  26  are inserted is prevented. Thus, it is possible to define the positions of the flow path component members by the positioning pins  26  while securing gas and liquid tightness of the sealed space  12 . 
     The first flow path member  14 , which is one of the flow path component members, is a member made of a synthetic resin that is provided with a plurality of guide flow paths  31  corresponding to the introduction pins  22 . The guide flow paths  31  guide the inks introduced through the introduction pins  22  to filter chambers  24  (described later) of the filter substrate  16 . The guide flow paths  31  communicate with the corresponding introduction pins  22  on the upper surface of the first flow path member  14 . Furthermore, each guide flow path  31  extends in a planar direction of the first flow path member  14  independently of the other guide flow paths  31  without intersecting the other guide flow paths  31 , and divides midway into two branch flow paths. The branch flow paths of each guide flow path  31  have separate openings in the lower surface of the first flow path member  14  and communicate with two filter chambers  24 . In this exemplary embodiment, corresponding to the four introduction pins  22 , a total of eight branch flow paths are formed in the first flow path member  14 . 
     The filter substrate  16 , which is one of the flow path component members, is provided with the filter chambers  24  in each of which a filter  25  is disposed. Each filter chamber  24  is a cavity whose upper surface side has an opening. In a bottom portion of each filter chamber  24 , a filter  25  is fixed. Each filter  25  filters ink flowing down through a corresponding one of ink flow paths and is, for example, a filter formed by finely weaving a metal into a mesh shape or a filter provided with many through holes formed by the plastic working of a thin metal sheet. When ink is contaminated with bubbles or undesired matter, the bubbles or the undesired matter is trapped in the filter chambers  24  by the filters  25  and therefore prevented from flowing into the head unit  13  side. Furthermore, the bottom portion of each filter chamber  24  has an opening of an outlet  32 . The outlets  32  communicate with supply flow paths  33  in the second flow path member  15  at the lower surface of the filter substrate  16 . 
     The second flow path member  15 , which is one of the flow path component members and a kind of flow path-isolating member, is a member provided with a plurality of supply flow paths  33  that supply the inks introduced from the filter chamber  24  side into head flow paths of the head units  13 . In this exemplary embodiment, a total of eight supply flow paths  33  extend independently of each other in planar directions of the second flow path member  15  without intersecting with each other. Each of the supply flow paths  33  of the second flow path member  15  communicates with the outlet  32  of a corresponding one of the filter chambers  24  at the upper surface of the second flow path member  15  and communicates with a communication opening  34  that penetrates through the second flow path member  15  in its plate thickness direction. Some of the communication openings  34  communicate with connection flow paths  36  in flow path-connecting portions  35  of a flow path-connecting member  19  through communication holes  37  of a seal member  18 , and also communicates with introduction flow paths  50  of the second case  11  through the connection flow paths  36 . The other communication openings  34  communicate with the introduction flow paths  50  by communicating with introduction portions  49  of the second case  11  through the communication holes  37  of the seal member  18 . That is, the seal member  18  liquid-tightly seals the liquid flow paths of the first case  10  side and the liquid flow paths of the second case  11  sides and thus provides communication therebetween. Note that the flow paths upstream of the communication holes  37  of the seal member  18  assumed as a boundary are considered the first case  10 -side flow paths and the flow paths downstream of the communication holes  37  are considered the second case  11 -side liquid flow paths. Furthermore, portions of the seal member  18  where the first case  10 -side liquid flow paths and the second case  11 -side liquid flow paths are connected by the communication holes  37  correspond to a connecting portion in the invention. 
       FIG. 5  is a bottom plan view of the second flow path member  15 .  FIG. 6  is a sectional view taken along line VI-VI in  FIG. 5 .  FIG. 7  is a sectional view taken along line VII-VII in  FIG. 5 . On the lower surface of the second flow path member  15 , a first perimeter wall  38  extends downward (to the second case  11  side) so as to surround a region in which the communication openings  34  are formed, and a second perimeter wall  39  similarly extends but is spaced outward by a predetermined interval from the first perimeter wall  38 . A trench formed along an outer perimeter of the second flow path member  15  between the first perimeter wall  38  and the second perimeter wall  39  (a portion indicated by hatching in  FIG. 5 ) functions as a fitting portion  40  into which an outside wall  51  of the seal member  18  is fitted. The fitting portion  40  is provided with an elongated narrow groove  41  extending along the extending directions of the fitting portion  40 . As shown in  FIG. 6 , the groove  41  defines a resistance pathway that is a portion of an atmospherically open passageway as the outside wall  51  of the seal member  18  is fitted to the fitting portion  40  so that an upper end surface of the outside wall  51  is in contact with the fitting portion  40 . This resistance pathway is a passageway whose cross-sectional area and length are predetermined so as to provide resistance to passage of moisture. The groove  41  has a first through opening  42  and a second through opening  43  that are formed at different locations. The first through opening  42  and the second through opening  43  are through holes that penetrate through the second flow path member  15  in its thickness direction. As shown in  FIG. 7 , the first through opening  42  communicates with the sealed space  12  in which the first flow path member  14  and the filter substrate  16  are disposed. That is, the sealed space  12  communicates with an atmospherically open passageway through the first through opening  42 . 
       FIG. 8  is a sectional view illustrating the atmospherically open passageway of the first case  10  and the flow path member  9 . The second through opening  43  communicates with an atmospherically open path  44  that is formed in the filter substrate  16 , the first flow path member  14 , and the first case  10 . The atmospherically open path  44  is a portion of an atmospherically open passageway which is formed by series connection of a first atmospheric communication path  45  provided in the filter substrate  16 , a second atmospheric communication path  46  provided in the first flow path member  14 , and a third atmospheric communication path  47  of the introduction pin baseboard  21  of the first case  10 . The passageway cross-sectional area of the atmospherically open path  44  is set sufficiently larger than the passageway cross-sectional area of the aforementioned resistance pathway. Furthermore, one end of the atmospherically open path  44  communicates with the second through opening  43  and another end thereof opposite to that one end communicates with the atmosphere through the through the atmospheric opening  48  of the first case  10 . Thus, the sealed space  12 , communicating with the first through opening  42  and the resistance pathway, further communicates with the second through opening  43  and the atmospherically open path  44  and is open to the atmosphere through the atmospheric opening  48 . This makes it possible to reduce pressure changes in the sealed space  12  while restraining moisture evaporation from the liquid flow paths provided in the sealed space  12  (i.e., while maintaining a high-humidity state). 
     The seal member  18 , the circuit board  17 , and the flow path-connecting member  19  are disposed between the second flow path member  15  of the first case  10  and the second case  11 . The seal member  18  is a member manufactured from, for example, an elastic material such as an elastomer, and is provided with the communication holes  37  having openings at positions that correspond to the positions of the communication openings  34  of the second flow path member  15 . The communication holes  37  are disposed between lower end openings of the communication openings  34  of the second flow path member  15  and upper end openings of the introduction portions  49  of the second case  11  or between lower end openings of the communication openings  34  and flow path-connecting portions  35  of the flow path-connecting member  19 , that is, disposed between first case  10 -side liquid flow paths and second case  11 -side liquid flow paths. As peripheral edge portions of openings of the communication holes  37  elastically closely contact peripheral edge portions of openings of the foregoing flow paths and thus achieves sealing, the first case  10 -side liquid flow paths and the second case  11 -side liquid flow paths communicate with each other in a liquid tight state. The upper and lower opening peripheral edge portions of each communication hole  37  are provided with a hollow cylindrical enclosing wall  37   a  (see  FIG. 2  and  FIG. 3 ) that is protruded to the first case  10  side and to the second case  11  side. Upper end surfaces and lower end surfaces of the enclosing walls  37   a  closely contact the second flow path member  15  and the circuit board  17 , respectively, and therefore seal connecting portions between the first case  10 -side liquid flow paths and the second case  11 -side liquid flow paths. 
     Furthermore, the outer peripheral edge of the seal member  18  is provided with the outside wall  51  extending from the outer peripheral edge to the first case  10  side and to the second case  11  side. When the seal member  18  is positioned and disposed between the second flow path member  15  and the circuit board  17 , the upper end portion of the outside wall  51  fits to the fitting portion  40  of the second flow path member  15  and contacts a portion of the second flow path member  15  which is provided with the groove  41 , so that the foregoing resistance pathway is formed. The lower end portion of the outside wall  51  contacts the upper surface of the second circuit board  17 . When the component members of the recording head  3  are stacked and assembled, the outside wall  51  of the seal member  18  is squeezed between the second flow path member  15  and the circuit board  17  and, due to its elasticity, closely contacts the second flow path member  15  and the circuit board  17 . Due to this, a flow path-connecting space  52  (see  FIG. 3 ) in which connecting portions between the first case  10 -side liquid flow paths and the second case  11 -side liquid flow paths is sealed by the outside wall  51  of the seal member  18  in a manner in which the outside wall  51  surrounds and encloses the flow path-connecting space  52 . That is, the connecting portions between the first case  10 -side liquid flow paths and the second case  11 -side liquid flow paths are double-sealed. This inhibits evaporation of moisture (a solvent) of ink from the connecting portions between the first case  10 -side liquid flow paths and the second case  11 -side liquid flow paths. Furthermore, in this exemplary embodiment, the connecting portions are further (triply) sealed by the enclosing wall  37   a  and the outside wall  51 , so that the evaporation of moisture (a solvent) of the inks in the liquid flow paths from the connecting portions is effectively inhibited. 
     The circuit board  17  is a so-called printed board. The circuit board  17  in this exemplary embodiment includes a connector  54  to which a flexible flat cable (FFC)  8  (see  FIG. 1 ) extending from the printer main body side is connected. The circuit board  17  receives control signals, such as drive signals, from the printer main body side through this FFC  8  and applies the signals to piezoelectric elements  71  (see  FIG. 9 ) of the head unit  13  through flexible boards  55 . That is, the circuit board  17  is a board that relays drive signals for driving the piezoelectric elements  71  as drive elements (active elements). The connector  54  is disposed at an outer side of the location at which a lower end surface of the outside wall  51  of the seal member  18  contacts the circuit board  17  to achieve the sealing. This allows the FFC  8  to be inserted into and pulled out from the connector  54  while maintaining the sealed state of the flow path-connecting space  52  in which the foregoing connecting portions are disposed. This circuit board  17  is provided with escape holes  56  through which the flexible boards  55 , the introduction portions  49  of the second case  11 , and the flow path-connecting portions  35  of the flow path-connecting member  19  are inserted. The circuit board  17  is disposed in the second case  11 , with the flow path-connecting member  19  interposed therebetween, in a state in which the circuit board  17  closes an upper surface-side opening above a region inside the second case  11  in which the flow path-connecting member  19  is disposed. 
     The flow path-connecting member  19  is a member made of a synthetic resin which is disposed between the circuit board  17  and the second case  11 . In this exemplary embodiment, an upper surface of the flow path-connecting member  19  is provided with a plurality of protruded hollow cylindrical flow path-connecting portions  35 . The recording head  3  in this exemplary embodiment is provided with a total of eight nozzle rows of which four nozzle rows correspond to a total of four flow path-connecting portions  35  provided on the flow path-connecting member  19 . As described above, each flow path-connecting portion  35  has therein a connection flow path  36 . An end of each connection flow path  36  communicates with a corresponding one of the communication openings  34  of the second flow path member  15  through a corresponding one of the communication holes  37  of the seal member  18  as described above. Another end of each connection flow path  36  communicates with a corresponding one of the introduction flow paths  50  through a planar flow path (not graphically shown) that extends in parallel with a nozzle surface of the second case  11 . Furthermore, the flow path-connecting member  19  is provided with escape holes  57  through which the flexible boards  55  and the introduction portions  49  of the second case  11  are inserted. 
     The second case  11  is a box-shaped member that houses a plurality of head units  13  in a housing chamber  59  formed therein. In the second case  11 , the introduction flow paths  50  that communicate with case flow paths  64  (described later) in the head units  13  inside the housing chamber  59  are formed corresponding to the nozzle rows of the head units  13 . Furthermore, the second case  11  is divided by a dividing wall  60  into upper and lower regions, that is, a region in which the flow path-connecting member  19  is disposed and a region in which the housing chamber  59  is formed. On an upper surface of the dividing wall  60 , a total of four protruded hollow cylindrical introduction portions  49  corresponding to the other four rows of the foregoing eight nozzle rows are provided as upper end portions of the introduction flow paths  50 . The introduction portions  49  communicate with the communication openings  34  of the second flow path member  15  through the communication holes  37  of the seal member  18  as described above. The flow path-connecting member  19  is disposed on the upper surface of the dividing wall  60  in a state in which the introduction portions  49  are inserted through the escape hole  57  of the flow path-connecting member  19 . Furthermore, the planar flow path has an end opening in the dividing wall  60  and that opening portion communicates with the connection flow paths  36  of the flow path-connecting member  19 . The dividing wall  60  further has board insertion openings  61  into which the flexible boards  55  are inserted. An end of each flexible board  55  is connected to the piezoelectric elements  71  of a corresponding one of the head units  13 , and another end thereof is passed through corresponding ones of the board insertion openings  61  and the escape holes  56  and  57 , drawn out onto the upper surface side of the circuit board  17 , and electrically connected to terminals of the circuit board  17 . 
     The housing chamber  59  of the second case  11  has an opening on a lower surface side of the second case  11 . In this exemplary embodiment, the housing chamber  59  houses a total of four head units  13  positioned and aligned in a direction that corresponds to the main scanning direction. Incidentally, in the invention, the number of head units  13  housed in the housing chamber  59  is not limited to four. Lower surfaces of the head units  13  in the housing chamber  59  (more concretely, lower surfaces of compliance substrates  68  described later) are fixed by an adhesive to a head cover  20  made of metal which is provided with four opening portions  62  that correspond one-to-one to the head units  13 . Furthermore, the head cover  20  is joined also to a lower surface of the second case  11  by an adhesive. Therefore, the head cover  20  and the seal member  18  seals a space in the second case  11 . 
       FIG. 9  is a sectional view of portions of a head unit  13  showing an internal construction thereof. In this exemplary embodiment, each head unit  13  is constructed by attaching a stack of a plurality of head unit component members to a head case  65  made of a synthetic resin. The head unit component members include a nozzle plate  66 , the compliance substrate  68 , a communication substrate  67 , a pressure chamber-forming substrate  69 , a vibration plate  70 , piezoelectric elements  71  (kind of drive elements), a protective substrate  72 , etc. 
     The pressure chamber-forming substrate  69  is manufactured from a silicon single-crystal substrate (hereinafter, also referred to simply as silicon substrate). The pressure chamber-forming substrate  69  is provided with a plurality of cavities for compartmentalizing pressure chambers  73 . The cavities are formed by an anisotropic etching process. The cavities penetrate through the pressure chamber-forming substrate  69  in its thickness direction. An end opening portion of each cavity is sealed by the vibration plate  70  and the other end opening portion thereof is sealed by the communication substrate  67  to form a pressure chamber  73 . Hereinafter, these cavities are also referred to as pressure chambers  73 . In this exemplary embodiment, because the nozzle plate  66  of each head unit  13  is provided with two nozzle rows each of which is made up of a plurality of aligned nozzles  75 , the pressure chamber-forming substrate  69  of each head unit  13  is provided with two rows of pressure chambers  73  corresponding to the two nozzle rows. Each pressure chamber  73  is a cavity elongated in a direction that interests (orthogonally intersects in this exemplary embodiment) the aligning direction of the nozzles  75  (nozzle row direction). When the pressure chamber-forming substrate  69  is positioned and joined to the communication substrate  67 , an end portion of each pressure chamber  73  in its longitudinal direction communicates with a nozzle  75  via a corresponding one of nozzle communication paths  74  formed in the communication substrate  67 . Furthermore, the other end portion of each pressure chamber  73  in its longitudinal direction communicates with a common liquid chamber  77  via a corresponding one of individual communication openings  76  formed in the communication substrate  67 . 
     An upper surface of the pressure chamber-forming substrate  69  (a surface opposite to a joining surface with the communication substrate  67 ) is provided with the vibration plate  70  that is formed to seal the upper openings of the pressure chambers  73 . This vibration plate  70  is formed from, for example, a silicon dioxide plate having a thickness of about 1 μm. An insulation film (not graphically shown) is formed on top of the vibration plate  70 . This insulation film is made of, for example, zirconium oxide. The piezoelectric elements  71  are formed at locations in the vibration plate  70  and the insulation film which correspond to the pressure chambers  73 . The piezoelectric elements  71  in this exemplary embodiment are so-called flexure mode piezoelectric elements. The piezoelectric elements  71  are formed separately for each pressure chamber  73  by sequentially stacking, on the vibration plate  70  and the insulation film, a lower electrode film made of a metal, a piezoelectric body layer made of a lead zirconate titanate (PZT) or the like, an upper electrode film made of a metal (none of which is graphically shown) and performing patterning. One of the upper electrode film and the lower electrode film is made a common electrode and the other is made individual electrodes. When a piezoelectric element  71  is driven, the vibration plate  70 , the insulation film, and the lower electrode film function as a drive region. 
     Each piezoelectric element  71  has a lead electrode extending out to the vibration plate  70 . One-end-side terminals of the flexible board  55  are connected to portions of the lead electrodes which correspond to electrode terminals. The flexible board  55  has a construction, for example, in which an electric conductor pattern is formed from copper foil or the like on a surface of a base film of a polyimide or the like and is coated with a resist. On a surface of the flexible board  55  there is mounted a drive IC  78  (see  FIG. 3 ) that is provided to drive a corresponding one of the piezoelectric elements  71 . Each piezoelectric element  71  produces flexure deformation when a drive signal (drive voltage) is selectively applied between the upper electrode film and the lower electrode film by the drive IC  78 . 
     The communication substrate  67  joined to the lower surface of the pressure chamber-forming substrate  69  is a platy member manufactured from a silicon substrate similarly to the pressure chamber-forming substrate  69 . The communication substrate  67  is provided with common liquid chambers  77  (referred to also as reservoirs of manifolds) that are cavities each of which is common to the pressure chambers  73  of a corresponding one of the pressure chamber rows. The common liquid chambers  77  are formed by anisotropic etching. The ink introduced through one of the introduction pins  22  flows down corresponding first case  10 -side liquid flow paths, that is, sequentially flows through corresponding guide flow paths  31 , filter chambers  24 , and supply flow paths  33 , passes through communication openings  34  of the second flow path member  15  and communication holes  37  of the seal member  18 , and then flows down corresponding second case  11 -side liquid flow paths, that is, sequentially through connection flow paths  36 , introduction flow paths  50 , and case flow paths  64 , and then flows into corresponding common liquid chambers  77 . The ink in the common liquid chambers  77  is supplied to the pressure chambers  73  through the individual communication openings  76  formed corresponding one-to-one to the pressure chambers  73 . 
     The compliance substrate  68  is joined to a lower surface of the communication substrate  67 . The compliance substrate  68  is a composite member made up of a thin compliance sheet  80  made of, for example, polyphenylene sulfide resin (PPS) or the like, and a sheet support plate  81  made of a metal which supports the compliance sheet  80 . Regions in the sheet support plate  81  which face the common liquid chambers  77  are each provided with a compliance opening  83  formed by removing a portion of the sheet support plate  81  so that the compliance openings  83  have a shape similar to the shape of lower surface openings of the common liquid chambers  77 . Therefore, the lower surface-side openings of the common liquid chambers  77  are sealed only by the compliance sheet  80  that has flexibility. In other words, the compliance sheet  80  compartmentalizes a portion of each common liquid chamber  77 . 
     Portions of a lower surface of the sheet support plate  81  which correspond to the compliance openings  83  are sealed by the head cover  20 . Therefore, the flexible regions of the compliance sheet  80  and the head cover  20  facing the flexible regions define therebetween compliance spaces  84 . The flexible regions of the compliance sheet  80  which partially define the compliance spaces  84  are displaced to the common liquid chamber  77  side or to the compliance space  84  side according to pressure changes in the ink flow paths and particularly in the common liquid chambers  77 . A central portion of the compliance substrate  68  is provided with a substrate opening portion  82  whose shape is similar to an external shape of the nozzle plate  66 . That is, when the compliance substrate  68  and the nozzle plate  66  are joined to the communication substrate  67 , the nozzle plate  66  is disposed in the substrate opening portion  82 . The compliance sheet  80  may be made up of any sheet material, for example, a metal sheet, such as a very thin stainless steel sheet, if the compliance sheet  80  is a flexible member that can flex according to pressure changes in the ink flow path (common liquid chamber  77 ). 
     The protective substrate  72  is disposed on the upper surface of the pressure chamber-forming substrate  69  on which the piezoelectric elements  71  are formed. This protective substrate  72  is a hollow box-shaped member and is manufactured from, for example, a silicon substrate or the like. A central portion of the protective substrate  72  is provided with a wiring cavity  85  that penetrates the protective substrate  72  in the substrate thickness direction. In the wiring cavity  85  there are disposed connecting portions between the lead electrodes of the piezoelectric elements  71  and an end portion of the flexible board  55 . Furthermore, regions in the protective substrate  72  which face the piezoelectric elements  71 , more concretely, regions therein on both sides of the wiring cavity  85  in a direction orthogonal to the pressure chamber aligning direction, are provided with storage spaces  86  having such a size as not inhibit the driving of the piezoelectric elements  71 . Each storage space  86  is formed from the lower surface of the protective substrate  72  (the joining surface with the pressure chamber-forming substrate  69 ) to an intermediate location in a substrate thickness direction to the upper surface side. 
     The nozzle plate  66  is a plate member provided with rows of nozzles  75  with a pitch corresponding to the dot formation density. The nozzle plate  66  has nozzle rows of a plurality of nozzles  75  aligned at a predetermined pitch. In this exemplary embodiment, the nozzle plate  66  of each head unit  13  has two nozzle rows. The two rows of nozzles of each one of the head units  13  are supplied with the same kind (color) of ink. In each set of two nozzle rows, the two nozzle rows are in a staggered arrangement in which the location of a given one of the nozzles  75  of one row in the nozzle row direction is different from the location of any adjacent one of the nozzles  75  of the other row. In this exemplary embodiment, the nozzle plates  66  are manufactured from a silicon substrate. By subjecting the substrate to dry etching, the hollow cylindrical nozzles  75  are formed. The longitudinal and lateral dimensions of the nozzle plate  66  are set smaller than the longitudinal and lateral dimensions of the substrate opening portion  82  of the compliance substrate  68  and the opening portion  62  of the head cover  20 . When the nozzle plate  66  is positioned and joined to the communication substrate  67 , the nozzle plate  66  is disposed in these opening portions  62  and  82 . In this state, the nozzle communication paths  74  of the communication substrate  67  communicate with the nozzles  75 . 
     The head case  65  is a box-shaped member made of a synthetic resin and a lower surface side thereof is joined to the communication substrate  67 . A central portion of the head case  65  is provided with a through cavity  88  (a portion of the wiring space) that penetrates through the head case  65  in its height direction. The through cavity  88  communicates with the wiring cavity  85  of the protective substrate  72 , forming a cavity in which the flexible board  55  is housed. A lower surface-side portion of the head case  65  is provided with the housing cavity  79  that recedes from the lower surface to an intermediate location in the height direction of the head case  65 . This housing cavity  79  has such a size that, when the head case  65  and the communication substrate  67  are positioned and joined, the housing cavity  79  is capable of housing the pressure chamber-forming substrate  69  disposed on the communication substrate  67 , the piezoelectric element  71 , the protective substrate  72 , etc. A lower end of the through cavity  88  has an opening in a ceiling surface of the housing cavity  79 . 
     The head case  65  is provided with the case flow paths  64  that penetrate through the head case  65  in its height direction. The case flow paths  64  are formed at locations apart from the housing cavity  79  of the head case  65  outward in a direction orthogonal to the pressure chamber aligning direction. More concretely, a total of two case flow paths  64  are formed at both sides of the housing cavity  79 , that is, one case flow path  64  on each side, corresponding to the common liquid chambers  77  of the communication substrate  67 . When the communication substrate  67  is joined to the head case  65 , each case flow path  64  communicates with a corresponding one of the common liquid chambers  77 . 
     The head cover  20  is, for example, a plate member made of a metal such as a stainless steel. In this exemplary embodiment, in order to expose the nozzles  75  formed in the nozzle plates  66 , portions of the head cover  20  which correspond in position to the nozzle plates  66  are provided, as described above, with the opening portions  62  whose shape is similar to the external shape of the nozzle plates  66  and which penetrate through the head cover  20  in its thickness direction. In this exemplary embodiment, the lower surface of the head cover  20  and the portions of the nozzle plates  66  exposed through the opening portions  62  of the head cover  20  form a nozzle surface. 
     In the recording head  3  constructed as described above, during a state in which the flow paths extending from the common liquid chambers  77  to the nozzles  75  through pressure chambers  73  are filled with ink, piezoelectric elements  71  are driven according to the drive signals from the drive ICs  78 , so that ink in corresponding ones of the pressure chambers  73  undergoes pressure changes and, due to the pressure changes, the corresponding nozzles  75  eject ink. 
     Thus, in the recording head  3  according to the invention, because the flow path member  9  is disposed in the sealed space  12  that is defined in the first case  10  as the first case  10  is joined to the second flow path member  15  that is a flow path-isolating member having high gas barrier property, that is, because the sealed space  12  is formed from a material having high gas barrier property, the evaporation of moisture (solvent component) of ink in the liquid flow paths of the flow path member  9  disposed in the sealed space  12  is inhibited. The thickening (viscosity increase) of ink in the liquid flow paths in the flow path member  9  is inhibited. Furthermore, according to this construction, since the thickening of ink in the flow path member  9  is inhibited, changes in ink ejection characteristics, such as the weight of ink ejected from the nozzles  75  and the flying speed of ejected ink, caused by the thickening of ink are inhibited. Therefore, the reliability of the printer  1  improves. Furthermore, in the printer  1 , it is possible to reduce the amount of ink consumed in a maintenance operation of discharging thickened ink from the nozzles  75  by performing ink suction while having the nozzle surface of the recording head  3  sealed by the cap  6 ′. 
     Furthermore, since one of the flow path component members of the flow path member  9  is the second flow path member  15  that functions also as a flow path-isolating member, it is unnecessary to provide a flow path-isolating member separately from the flow path component members and therefore it becomes possible to reduce the size of the recording head  3 . The material cost can also be reduced. 
     Furthermore, in the exemplary embodiment, since the sealed space  12  is defined as the first case  10  having higher gas barrier property compared to the seal member  18  is joined to the second flow path member  15 , the evaporation of moisture of ink in the liquid flow paths of the flow path member  9  disposed in the sealed space  12  is inhibited. 
     By the way, the invention is not limited to the foregoing exemplary embodiments but may be modified or changed in various manners based on what are described in the appended claims. 
       FIG. 10  is a sectional view of a positioning pin and portions around the positioning pin in a second exemplary embodiment. In the first exemplary embodiment, of the flow path component members of the flow path member  9 , the second flow path member  15  that functions also as a flow path-isolating member is provided with the positioning recess portions  29  into which distal end portions of the positioning pins  26  can be fitted, and the positioning pins  26  are covered with the first flow path member  14 , the filter substrate  16 , and the second flow path member  15  when the positioning pins  26  are disposed in the sealed space  12 . However, the invention is not limited to this construction. A second flow path member  15  in the second exemplary embodiment similarly to the first flow path member  14  and the filter substrate  16 , is provided with positioning holes  89  (that correspond to an insertion hole in the invention) through which the positioning pins  26  can be inserted and which penetrates the second flow path member  15  in its plate thickness direction. The positioning pins  26  are inserted through the positioning holes  27 ,  28  and  89  of these flow path component members and distal end portions of the positioning pins  26  in the positioning holes  89  of the second flow path member  15  are exposed to an outer side of the flow path member  9  (to the lower surface side of the second flow path member  15 ). In this exemplary embodiment, the distal end portions of the positioning pins  26  exposed in the positioning holes  89  are sealed by a sealer  90  such as an epoxy-based adhesive. Thus, the positioning pins  26  are covered by the first flow path member  14 , the filter substrate  16 , the second flow path member  15 , and the sealer  90  when the positioning pins  26  are disposed in the sealed space  12 . Therefore, the sealed space  12  is prevented from communicating with the atmosphere via the positioning holes  27 ,  28  and  89  through which the positioning pins  26  are inserted, so that it becomes possible to position the flow path component members by the positioning pins while securing gas tightness and liquid tightness of the sealed space  12 . Incidentally, other constructions of the second exemplary embodiment are the same as those of the first exemplary embodiment. 
     Furthermore, although the foregoing exemplary embodiments having described above in conjunction with an example construction in which the resistance pathway in the atmospherically open passageway is formed by the outside wall  51  of the seal member  18  closely contacting the groove  41  formed in the second flow path member  15 , the invention is not limited to this construction. For example, a resistance pathway may be formed by joining flow path component members. In this case, for example, if at least one of the flow path component members is provided with a groove similar to the groove  41 , the resistance pathway can be defined by joining the grooved flow path component member to the other flow path component member with an adhesive so that the opening of the groove is sealed. According to this construction, as the resistance pathway is formed by joining flow path component members that are high in gas barrier property, the evaporation of moisture from the resistance pathway is further reduced. 
     Furthermore, although the foregoing exemplary embodiments show the first flow path member  14 , the filter substrate  16 , and the second flow path member  15  as examples of the flow path component members that constitute the flow path member  9 , this construction does not restrict the invention. In short, a construction that includes at least one flow path component member and a flow path-isolating member suffices. 
     Although the foregoing description has presented the ink jet type recording head  3  (head units  13 ) as an example of a liquid ejecting head, the invention can also be applied to other liquid ejecting heads that include flow path members. For example, the invention is also applicable to color material ejecting heads for use in production of color filters for liquid crystal displays and the like, electrode material ejecting heads for use in electrode formation for organic electro-luminescence (EL) displays, field emission displays (flat panel displays), etc., bioorganic material ejecting heads for use in production of biochips (biochemical devices), and so forth. 
     The entire disclosure of Japanese Patent Application No. 2016-035216, filed Feb. 26, 2016 and Japanese Patent Application No. 2017-007224, filed Jan. 19, 2017 are expressly incorporated by reference herein.