Patent Publication Number: US-7914124-B2

Title: Liquid supplying device and liquid ejection apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2006-085703, filed on Mar. 27, 2006, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid supplying device and a liquid ejection apparatus. 
     2. Related Art 
     An ink jet printer (hereinafter referred to as a printer) is widely known as a liquid ejection apparatus for ejecting liquid onto a target. The printer has a recording head (liquid ejection head) mounted on a carriage that reciprocates. The recording head is supplied with ink (liquid) from an ink cartridge (liquid container) mounted on the printer at a predetermined location. The ink is ejected to a paper, which serves as a target, from a nozzle formed in a nozzle formation surface of the recording head to perform printing. 
     Such a printer is disclosed in, for example, JP-A-2005-95861. The printer is provided with a carriage including a valve unit (liquid supplying device) having a liquid supply passage for supplying ink from an ink cartridge to a recording head. In the valve unit, a pressure chamber (liquid storage unit) for temporarily storing ink is defined in the liquid supply passage. The pressure chamber is formed by a flow passage formation body, which has a fixed shape, and a flexible film. Further, the pressure chamber includes an entrance, which is in communication with the upstream side of the liquid supply passage extending from the ink cartridge, and an exit, which is in communication with the downstream side of the liquid supply passage extending from the recording head. 
     An open/close valve that opens and closes to regulate the flow of ink from the entrance to the pressure chamber is arranged in the liquid supply passage. The film is displaced when sensing negative pressure generated as the ink in the pressure chamber decreases due to ink ejection from the recording head. The displacement of the film opens and closes the open/close valve to adjust the supply pressure of the ink supplied from the ink cartridge to the recording head. 
     To enable multi-color printing, recent printers include a plurality of ink cartridges containing different colors of ink. Further, a plurality of nozzle rows respectively corresponding to the ink cartridges are formed in the nozzle formation surface of the recording head. A plurality of liquid supply passages are formed between the ink cartridges and the corresponding nozzle rows. The liquid supply passages enable ink to be supplied from the ink cartridges to the corresponding nozzle rows. A pressure chamber is arranged in each liquid supply passage. The displacement of a film opens and closes an open/close valve to regulate the inward flow of the ink. The pressure chamber, which is formed by a flow passage formation body and a film, is arranged in each liquid supply passage. The printer disclosed in JP-A-2005-95861 has a similar structure, and the printer includes two valve units, each having two liquid supply passages with a pressure chamber arranged in each liquid supply passage. 
     However, in the structure in which a liquid supply passage and a pressure chamber are formed in each of the plurality of valve units, the flow passage formation body and the film that forming the pressure chamber differs between each valve unit. Thus, the liquid supply passages and the pressure chambers arranged in different valve units may differ between one another in the behavior of the negative pressure generated in the pressure chamber, the open/close timing of the open/close valve that corresponds to the displacement of the film based on the negative pressure, and the supply of the ink through the liquid supply passages. Accordingly, the ejection state of the ink ejected from the recording head varies between the nozzle rows, and satisfactory printing cannot be performed. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a liquid supplying device that supplies liquid with liquid supply passages in a uniform manner when liquid is supplied through the liquid supply passages from a plurality of liquid containers to a plurality of nozzle rows in a liquid ejection head. 
     To achieve the above object, one aspect of the present invention provides a liquid supplying device for supplying liquid that is supplied from a plurality of liquid containers to a liquid ejection head including a plurality of nozzle rows respectively corresponding to the plurality of liquid containers. The liquid supplying device includes a plurality of liquid supply passages and at least one flow passage formation body. Each of the liquid supply passages is capable of supplying liquid supplied from a corresponding one of the liquid containers to a corresponding one of the nozzle rows. Each of the liquid supply passages includes a common portion that is functionally in common with another one of the liquid supply passages. The common portions of the plurality of liquid supply passages are formed in the same flow passage formation body. 
     A further aspect of the present invention provides a liquid ejection apparatus including a plurality of liquid containers, a liquid ejection head, a plurality of liquid supply passages, and at least one flow passage formation body. The liquid ejection head includes a plurality of nozzle rows respectively corresponding to the plurality of liquid containers. Each of the liquid supply passages is capable of supplying liquid supplied from a corresponding one of the liquid containers to a corresponding one of the nozzle row. Each of the liquid supply passages includes a common portion that is functionally in common with another one of the liquid supply passages. The common portions of the plurality of liquid supply passages are formed in the same flow passage formation body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
         FIG. 1  is a schematic plan view showing an ink jet printer of the present embodiment; 
         FIG. 2  is a cross-sectional view showing the structure of an ink cartridge of  FIG. 1 ; 
         FIG. 3  is a perspective view showing a valve unit of  FIG. 1 ; 
         FIG. 4  is an exploded perspective view showing a protection plate from a diagonally upward direction; 
         FIG. 5  is an exploded perspective view showing the protection plate from a diagonally downward direction; 
         FIG. 6  is a cross-sectional view of the protection plate; 
         FIG. 7  is an exploded perspective view showing a pressure chamber component; 
         FIG. 8  is a plan view showing the pressure chamber component; 
         FIG. 9  is a bottom plan view showing the pressure chamber component; 
         FIG. 10  is a perspective view showing a first flow passage component; 
         FIG. 11  is a perspective view showing a second flow passage component; 
         FIG. 12  is a perspective view showing a movable valve; 
         FIG. 13  is a perspective view showing a seal spring; 
         FIG. 14  is an exploded side view showing the procedures for assembling the valve unit; 
         FIG. 15  is a perspective view showing the step of setting the protection plate; 
         FIG. 16  is a perspective view showing the step of stacking the pressure chamber component; 
         FIG. 17  is a perspective view showing the step of stacking the first flow passage component; 
         FIG. 18  is a perspective view showing the step of attaching movable valves and seal springs; 
         FIG. 19  is a perspective view showing the step of stacking the second flow passage component; 
         FIG. 20  is a perspective view showing the step of attaching a head case to the valve unit; 
         FIG. 21  is a perspective view showing the head unit of  FIG. 1 ; and 
         FIG. 22  is a schematic cross-sectional view taken along line  22 - 22  in  FIG. 21 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     One embodiment embodying the present invention will now be described according to  FIGS. 1 to 22 . 
     As shown in  FIG. 1 , an ink jet printer (hereinafter referred to as a “printer”)  10 , which serves as a liquid ejection apparatus of the present embodiment, includes a main body case  11  having a rectangular shape when seen from above. A rod-shaped guide shaft  12  is arranged in the main body case  11 , and the guide shaft  12  extends in the longitudinal direction (lateral direction in  FIG. 1 ) of the main body case  11 . The guide shaft  12  supports a carriage  14 , on which a recording head  13  serving as a liquid ejection head is mounted. The carriage  14  reciprocates in the longitudinal direction of the guide shaft  12 . 
     A cartridge holder  15  is arranged in the main body case  11  at a position (right end side position in  FIG. 1 ) outside the movement range of the carriage  14 . A plurality of (four in the present embodiment) ink cartridges  16  serving as liquid containers are detachably attached to the cartridge holder  15 . That is, the printer  10  of the present embodiment is not a so-called on-carriage type printer, in which the ink cartridge is mounted on the carriage to move together with the carriage, but is a so-called off-carriage type printer, in which the ink cartridge  16  is fixed at a location separated from the carriage  14  and does not move together with the carriage  14 . The number of ink cartridges  16  corresponds to the number of ink colors (e.g., the colors of black, yellow, magenta, cyan) used in the printer  10 . 
     A drive pulley  17  and a driven pulley  18  are rotatably supported on the main body case  11 . The drive pulley  17  and the driven pulley  18  are located at positions corresponding to the two ends of the guide shaft  12  on the inner surface of the rear wall of the main body case  11 . An endless timing belt  19  connects the drive pulley  17  and the driven pulley  18 . A carriage motor  20  fixed to the rear wall of the main body case  11  has an output shaft (not shown) coupled to the drive pulley  17 . The drive force of the carriage motor  20  transmitted by the timing belt  19  reciprocates the carriage  14  in the direction of the guide shaft  12  (lateral direction of  FIG. 1 ), that is, the main scanning direction. 
     A platen  21  arranged below the guide shaft  12  in the main body case  11  extends in the lateral direction. The platen  21  is a support base for supporting paper (not shown), which serves as a target, and feeds the paper towards the front side (lower side in  FIG. 1 ) of the printer  10  as a paper feeding motor (not shown) produces rotation. 
     A valve unit  22 , which serves as a liquid supplying device is mounted on the carriage  14 , supplies the ink (liquid) supplied from each ink cartridge  16  to the recording head  13 . A plurality (four in the present embodiment) ink supply tubes  23  is connected to the valve unit  22 . Each ink supply tube  23  is connected to a corresponding one of the ink cartridges  16 . This enables ink to be supplied from each ink cartridge  16  to the valve unit  22 . The valve unit  22  temporarily stores ink drawn from each ink cartridge  16  via the corresponding ink supply tube  23 , adjusts the stored ink to a predetermined pressure, and supplies the ink to the corresponding nozzle row  13 A (see  FIG. 20 ) of the recording head  13 . Each ink supply tube  23  forms part of a liquid supply passage for supplying ink from the corresponding ink cartridge  16  to the recording head  13 . 
     A pressurizing unit  24  is arranged above the cartridge holder  15  in the main body case  11 . The pressurizing unit  24 , which includes a pressurizing pump  26 , a pressure sensor  27 , and an atmospheric valve  28 , sends the pressurized air (pressurized gas) to the ink cartridges  16  through an air supply tube  25 . The air supply tube  25  is branched into a plurality (four in the present embodiment) of tubes from a distributor  29  arranged downstream from the atmospheric valve  28 . Each branched tube is connected to a corresponding one of the ink cartridges  16 . 
     As shown in  FIGS. 1 and 2 , each ink cartridge  16  has a box-shaped ink case  30 . An ink pack  31  containing ink is accommodated in the ink case  30 . An ink supply connection port  32  extending through one side wall (right wall as viewed in  FIG. 2 ) of the ink case  30  is located at a generally middle position of the side wall with respect to the vertical direction. A tubular ink discharge port  31   a  formed integrally with the ink pack  31  has a distal end fitted into the ink supply connection port  32  and exposed from the ink case  30 . An ink supply tube  23  is connected to the ink discharge port  31   a.    
     An air supply connection port  33  extends through one side wall of the ink case  30 . The air supply connection port  33  is located below the ink supply connection port  32 . A tubular connection tube  34  is fitted into the air supply connection port  33 . The connection tube  34  has a first end (right end in  FIG. 2 ) exposed from the ink case  30  and a second end located in the ink case  30 . The distal end of an air supply tube  25  extending from the pressurizing pump  26  as described above is connected to the first end of the connection tube  34  that is exposed from the ink case  30 . A hermetic air chamber  35  is formed between the inner surface of the ink case  30  and the outer surface of the ink pack  31 . 
     When the pressurizing pump  26  is driven to feed pressurized air into the air chamber  35  of the ink case  30  through the air supply tube  25 , the ink pack  31  is squeezed by the air pressure (pressurized force) of the pressurized air. The squeezed ink pack  31  supplies the ink in the ink pack  31  to the valve unit  22  via the ink supply tube  23 . 
     The valve unit  22  will now be described. 
     As shown in  FIG. 3 , the valve unit  22  includes a pressure chamber component  36 , a first flow passage component  37 , a second flow passage component  38 , and a generally flat protection plate  39 . The pressure chamber component  36 , the first flow passage component  37 , and the second flow passage component  38  are thin plates and form a flow passage formation body having a fixed shape. The valve unit  22  is a single unit formed by stacking from the bottom the second flow passage component  38 , the first flow passage component  37 , the pressure chamber component  36 , and the protection plate  39 . The detailed structure of the protection plate  39 , the pressure chamber component  36 , the first flow passage component  37 , and the second flow passage component  38  will be described below. With regard to each of the above components, the surface located on the upper side as viewed in  FIG. 3  in the stacked state is referred to as the front surface and the surface located on the lower side is referred to as the rear surface. 
     The detailed structure of the protection plate  39  will first be described. 
     As shown in  FIGS. 4 to 6 , the protection plate  39  is a resin plate and has a rectangular cutaway portion  40  formed in the vicinity of one of the two long sides. Four cylindrical bushings  41  are arranged on the rear surface of the protection plate  39 . A threaded hole  41   a  is formed in the distal end surface of each cylindrical bushing  41 . As shown in  FIGS. 5 and 6 , a plurality of (four in the present embodiment) identical conduit recesses  42  are formed in the rear surface of the protection plate  39 . The conduit recesses  42  extend parallel to one another in the longitudinal direction of the protection plate  39 . A through hole  43  having a small diameter is formed in the bottom surface of each conduit recess  42 . The through hole  43  is located near one end of each conduit recess  42 . 
     A seal film  44  serving as a film member is thermally welded and attached to the rear surface of the protection plate  39  so as to cover the plurality of conduit recesses  42 . The seal film  44  is a flexible thin film. The seal film  44  is subjected to pressure molding in advance so that the regions corresponding to the conduit recesses  42  are dome-shaped and slightly curved into the conduit recesses  42 , as shown in  FIG. 6 . An air chamber  45  is formed between the seal film  44  and each conduit recess  42 . Positioning holes  46  corresponding to two of the four cylindrical bushings  41  of the protection plate  39  are formed in the seal film  44 . The positioning holes  46  function as a positioning portion for guiding the corresponding cylindrical bushings  41  when attaching the seal film  44  to the rear surface of the protection plate  39  so that the curved regions of the seal film  44  are arranged at appropriate positions corresponding to the conduit recesses  42 . 
     As shown in  FIG. 4 , a series of groove portions  47 , which are in communication with the through holes  43 , are extend in a meandering manner in the front surface of the protection plate  39 . Atmospheric communication holes  48  having a small diameter extend through the groove portions  47  at positions separated from the conduit recess  42  in the rear surface of the protection plate  39 . A barrier film  49  having high gas barrier properties is thermally welded and attached to the front surface of the protection plate  39  so as to cover the through holes  43 , the series of groove portions  47 , and the atmospheric communication holes  48 . The barrier film  49  may be a film made of polyethylene, polypropylene, polyester, polyamide, or the like on which aluminum, silica, or the like is deposited. 
     Pilot holes  39   a  functioning as the positioning portions extend through the protection plate  39  in the vicinity of the two corners on one of the two short sides (the closer short side as viewed in  FIGS. 3 and 4 ) of. Among the two pilot holes  39   a , the main pilot hole  39   a  located near the cutaway portion  40  is round and the other sub-pilot hole  39   a  is oval. 
     The detailed structure of the pressure chamber component  36  will now be described. 
     As shown in  FIGS. 7 to 9 , the pressure chamber component  36  is a rectangular resin plate and has a plurality of (four in the present embodiment) of identical conduit flow passages (part of liquid supply passage)  50  formed in the front surface so as to respectively correspond to the plurality of conduit recesses  42  in the protection plate  39 . The plurality of conduit flow passages  50  are identical and extend parallel to one another in the longitudinal direction of the pressure chamber component  36 . When the protection plate  39  is joined with the pressure chamber component  36 , openings  50   a  of the conduit flow passages  50  are sealed by the seal film  44  on the rear surface of the protection plate  39 . Each conduit flow passage  50  defines a pressure chamber  50 A (see  FIG. 22 ) sealed by the seal film  44 . 
     An entrance  51  having a small diameter extends through the inner bottom surface of each conduit flow passage  50  near a first end, and an exit  52  having a small diameter extends through the inner bottom surface of each conduit flow passage  50  near a second end. A rectangular seat  53  projects from the front surface of the pressure chamber component  36  in the vicinity of one of the two long sides. The seat  53  is fitted to the cutaway portion  40  of the protection plate  39  for positioning when joining the pressure chamber component  36  and the protection plate  39 . A plurality of (four in the present embodiment) of liquid inlets  54  extend through the seat  53 . The downstream end of an ink supply tube  23  is connected to each liquid inlet  54 . 
     Cutaway portions  55 , which engage two of the four cylindrical bushings  41  on the protection plate  39  when the pressure chamber component  36  and the protection plate  39  are joined, are formed at the two corners at a first end side in the longitudinal direction of the pressure chamber component  36 . Two positioning pins  56  spaced by a fixed distant in the lateral direction of the pressure chamber component  36  are arranged near the first longitudinal end of the pressure chamber component  36  on the front surface of the pressure chamber component  36 . The positioning pins  56  project upward. 
     Two insertion holes  57  enabling the insertion of the two remaining cylindrical bushings  41  on the protection plate  39  extend through the pressure chamber component  36  near the second longitudinal end. The insertion holes  57  serve as the positioning portions. A pilot hole  58  (positioning portion) aligned with the pilot hole  39   a  of the protection plate  39  when the pressure chamber component  36  and the protection plate  39  are joined extends through the vicinity of each insertion hole  57 . 
     Furthermore, an atmospheric communication hole  59  extends through the front surface of the pressure chamber component  36  in the vicinity of the insertion hole  57 , as shown in  FIGS. 7 and 8 . The atmospheric communication hole  59  is aligned with one of the two atmospheric communication holes  48  of the protection plate  39  when the pressure chamber component  36  and the protection plate  39  are joined. 
     Moreover, an adhesive application portion  36   a  is arranged on the front surface of the pressure chamber component  36  around each conduit flow passage  50 , each insertion hole  57 , and each pilot hole  58 , as shown in  FIG. 7 . The adhesive application portion  36   a  is the region in which an adhesive is applied to join the pressure chamber component  36  and the protection plate  39 . When adhesive is applied to this region and the pressure chamber component  36  and protection plate  39  are joined with each other, the portion of the seal film  44  corresponding to the adhesive application portion  36   a  is the adhered region. 
     As shown in  FIGS. 7 and 8 , an elastic plate (elastic member)  62  is attached to the front surface of the pressure chamber component  36 . The elastic plate  62  includes a base portion  61  and a plurality of (four in the present embodiment) elastic strips  60  extending from the base portion  61  in a comb-like manner to form actuating levers. Each elastic strip  60  corresponds to one of the conduit flow passage  50 . Two press-fitting holes  63  are formed in the base portion  61  of the elastic plate  62 . The two positioning pins  56  of the pressure chamber component  36  are inserted into and press-fitted to the two press-fitting holes  63 . This connects the elastic plate  62  to the pressure chamber component  36  so that each elastic strip (actuating lever) is cantilevered in the corresponding conduit flow passage  50 . 
     A plurality of (four in the present embodiment) valve receptacles  64  are formed in the rear surface of the pressure chamber component  36 . Each valve receptacle  64  corresponds to one of the entrances  51  and is aligned coaxially with the corresponding entrance  51 , as shown in  FIG. 9 . Further, in the rear surface of the pressure chamber component  36 , two conical recesses  66  and  67  are formed between one longitudinal end of the pressure chamber component  36  and the four valve receptacles  64  (each entrance  51 ), and two conical recesses  68  and  69  are formed between the four valve receptacles  64  and the four exits  52 . The recesses  66  to  69  are identically shaped. 
     As shown in  FIG. 9 , ink flow passages (part of liquid supply passage)  65   a  for respectively connecting two of the recesses  66  to  69  that are located near the liquid inlet  54 , namely, the recesses  66  and  68 , to the liquid inlets  54  that are second and fourth from the top as viewed in  FIG. 9  are formed on the rear surface of the pressure chamber component  36  so as to directly draw ink into the recesses  66  and  68  from the liquid inlets  54 . Ink flow passages (part of liquid supply passage)  65   b  extend in the rear surface of the pressure chamber component  36  from the two remaining recesses  67  and  69  to predetermined positions. At locations in the rear surface of the pressure chamber component  36  corresponding to the exits  52 , ink flow passages (part of liquid supply passage)  65   c  are formed to guide ink that flows out of the conduit flow passages  50  through the exits  52  from the front surface to the rear surface in the front surface towards four spaced positions located in four different directions. 
     An adhered region  36   b  is defined on the rear surface of the pressure chamber component  36  around the liquid inlets  54 , the valve receptacles  64 , the ink flow passages  65   a ,  65   b , and the recesses  66  to  69 . Adhesive applied to the first flow passage component  37  adheres to the adhered region  36   b  when joining the pressure chamber component  36  and the first flow passage component  37 . 
     As shown in  FIG. 9 , a nut receptacle  36   c  for receiving a hexagon nut (not shown) is formed in the vicinity of each cutaway portion  55  of the pressure chamber component  36  outside the adhered region  36   b . Furthermore, a nut receptacle  36   c  for receiving a hexagon nut (not shown) is formed in the vicinity of the second end of the pressure chamber component  36  outside the adhered region  36   b.    
     The detailed structure of the first flow passage component  37  will now be described. 
     As shown in  FIG. 10 , the first flow passage component  37  is a resin rectangular plate and having an outer contour substantially identical to the pressure chamber component  36  when viewed in the stacking direction. More specifically, the outer contour of the first flow passage component  37  differs from that of the pressure chamber component  36  only in that the cutaway portions  55  formed in the pressure chamber component  36  whereas the first flow passage component  37  does not have such cutaway portions. 
     As shown in  FIG. 10 , flow passages, recesses, and holes are formed in the front surface of the first flow passage component  37  in mirror relationship with the rear surface of the pressure chamber component  36 . Specifically, a plurality of (four in the present embodiment) recesses  70  to  73  corresponding to the plurality of recesses  66  to  69  of the pressure chamber component  36  are formed in the front surface of the first flow passage component  37 . When the pressure chamber component  36  and the first flow passage component  37  are joined, the recess  66  is aligned with the recess  70 , the recess  67  is aligned with the recess  71 , the recess  68  is aligned with the recess  72 , and the recess  69  is aligned with the recess  73 . 
     A round inlet filter member  74  made of a metal mesh is thermally welded and attached to a large diameter portion of each of the recesses  70  to  73  in the first flow passage component  37 . The inlet filter member  74  filters the ink that flows into the valve unit  22  from the liquid inlets  54  to capture foreign matter in the ink. In the present embodiment, the mesh roughness of the inlet filter member  74  is set to about 29 microns to capture foreign matter that is larger than 30 microns. 
     As shown in  FIG. 10 , ink passages  75  extend through the front surface of the first flow passage component  37 . The ink passages  75  are aligned with the first and third liquid inlets  54  from the top of the pressure chamber component  36  as viewed in  FIG. 9 . Ink flow passages (part of liquid supply passage)  76   a  respectively extend towards the two recesses  70  and  72  from locations corresponding to the remaining second and fourth liquid inlets  54 . Each ink flow passage  76   a  is formed in mirror relationship with the corresponding ink flow passage  65   a  formed in the rear surface of the pressure chamber component  36 . 
     Ink flow passages (part of liquid supply passage)  76   b  shaped identically to the ink flow passage  65   b  are formed in the front surface of the first flow passage component  37  at locations corresponding to the ink flow passages  65   b  of the pressure chamber component  36  and extend from the recesses  71  and  73  to predetermined positions. A through hole  77  is formed in the inner bottom surface of the distal end of each ink flow passage  76   b . The through holes  77  are connected to the ink passages  75  described above through ink flow passages (not shown) formed in the rear surface of the first flow passage component  37 . The ink supplied from the liquid inlets  54  located at the upstream side is guided to the recess  67  and  69  flowing through the ink passages  75 , the ink flow passages in the rear surface (not shown), the through holes  77 , and then the ink flow passages  76   b  in the front surface. 
     A plurality of (four in the present embodiment) valve receptacles  78  extends through the first flow passage component  37  at location corresponding to the plurality of valve receptacles  64  of the pressure chamber component  36 . Each valve receptacle  78  has a mirror relationship with the corresponding valve receptacle  64 . Ink is guided to the valve receptacles  78  from the recesses  70  to  73  located at the upstream side through holes (not shown) extending through the inner bottom surface of the recesses  70  to  73  and ink flow passage (not shown) formed continuously from the passage holes in the rear surface of the first flow passage component  37   e.    
     Threaded insertion hole  79  is formed in the front surface of the first flow passage component  37  at locations corresponding to the cutaway portions  55  of the pressure chamber component  36 . Each threaded insertion hole  79  is aligned with the distal end surface (i.e., threaded hole  41   a ) of the corresponding one of the cylindrical bushings  41  on the protection plate  39  when the pressure chamber component  36  and the protection plate  39  are stacked on the first flow passage component  37 . Two insertion holes  80  and two pilot holes (positioning portions)  81  extend through the front surface of the first flow passage component  37 . Each of the insertion holes  80  and pilot holes  81  is aligned with the corresponding ones of the insertion holes  57  and the pilot holes  58  of the pressure chamber component  36 . 
     As shown in  FIG. 10 , an adhesive application portion  37   a  corresponding to the adhered region  36   b  of the pressure chamber component  36  described above is formed on the front surface of the first flow passage component  37  around the recesses  70  to  73 , the ink passage  75 , the ink flow passages  76   a  to  76   c , and the valve receptacles  78 . Furthermore, a plurality of (only two are shown in  FIG. 10 ) threaded insertion holes  37   b  are formed outside the adhesive application portion  37   a . Each threaded insertion hole  37   b  is aligned with the corresponding nut receptacle  36   c  of the pressure chamber component  36 . 
     The detailed structure of the second flow passage component  38  will now be described. 
     As shown in  FIG. 11 , the second flow passage component  38  is a resin plate having a rectangular shape in plan view and having an outline shape substantially the same as the first flow passage component  37  when seen in the stacking direction. That is, the second flow passage component  38  differs from the first flow passage component  37  in outline shape in that one end side region is formed longer than the first flow passage component  37 , and a terminal insertion part  82  is formed at such one end side region. 
       FIG. 11  is a perspective view showing the second flow passage component  38 . As shown in the drawing, flow passages, recesses, and holes are formed in the front surface of the second flow passage component  38  in mirror relationship with the rear surface of the first flow passage component  37 . Specifically, a plurality of (four in the present embodiment) recesses  83  corresponding to recesses (not shown, recesses extending about the through holes  77 ) formed in the rear surface of the first flow passage component  37  are formed in the front surface of the second flow passage component  38 . A liquid outlet  84  extends through the inner bottom surface of each recess  83 . The liquid outlet  84  becomes the outlet for ink exiting the valve unit  22 . 
     A round outlet filter member  85  made of a metal mesh is thermally welded and attached to the large diameter portion of each recess  83  of the second flow passage component  83 . The outlet filter members  85  filter the ink flowing out of the valve unit  22  through the liquid outlets  84  and captures foreign matter in the ink. In the present embodiment, the mesh roughness of the outlet filter member  85  is set to about 19 microns to capture foreign matter smaller than 20 microns, which is equivalent to the diameter of a nozzle  13   a  (see  FIG. 22 ) of the recording head  13 . That is, the outlet filter members  85  capture further finer matter than the inlet filter members  74 . 
     As shown in  FIG. 11 , a plurality of (four in the present embodiment) tubular seats  86  insertable into the valve receptacles  78  project from the front surface of the second flow passage component  38  at locations corresponding to the four valve receptacles  78  of the first flow passage component  37 . Each tubular seat  86  is a cylindrical body in which the distal end side has a smaller diameter than the basal end side and in which the cross-section is substantially C-shaped by cutting away part of the side wall of the cylindrical body in the vertical direction. A plurality of ink flow passages (one part of liquid supply passage)  87  are formed in the front surface of the second flow passage component  38 . Each ink flow passage  87  is in communication with the inner side of the corresponding tubular seat  86  through the cutaway portion. The ink flow passages  87  extend to communicate the tubular seats  86  to through holes (not shown) formed in the inner bottom surface of the recesses  70  to  73  of the first flow passage component  37  when the first flow passage component  37  is stacked on the second flow passage component  38 . 
     Threaded insertion holes  88  are formed in the front surface of the second flow passage component  38  at locations corresponding to the two threaded insertion holes  79  of the first flow passage component  37 . Insertion holes  89  and pilot holes (positioning portion)  90  extend through the front surface of the second flow passage component  38  at locations corresponding to the insertion holes  80  and the pilot holes  81  of the first flow passage component  37 . 
     As shown in  FIG. 11 , an adhesive application portion  38   a  corresponding to the adhering region (not shown) defined on the rear surface of the first flow passage component  37  is formed on the front surface of the second flow passage component  38  around the recesses  83 , the ink flow passages  87 , and the threaded insertion holes  88 . Threaded insertion holes  38   b  corresponding to the threaded insertion holes  37   b  of the first flow passage component  37  are formed outside the adhesive application portion  38   a  in the front surface of the second flow passage component  38 . 
     When the first flow passage component  37  and the pressure chamber component  36  are stacked on the second flow passage component  38 , a movable valve (open/close valve)  91  shown in  FIG. 12  is received in each valve receptacle  78  of the first flow passage component  37  and each valve receptacle  64  of the pressure chamber component  36 . A seal spring  92  shown in  FIG. 13  is attached to the tubular seat  86  of the second flow passage component  38 . 
     The movable valve  91  includes a shaft portion  91   a , which is insertable into an entrance  51  of the pressure chamber component  36 , and a flange portion  91   b , which is movable in the axial direction of the shaft portion  91   a  in the valve receptacle  64  of the pressure chamber component  36  and the valve receptacle  78  of the first flow passage component  37 , as shown in  FIG. 12 . An annular seal portion  91   c  made of an elastomer or the like is formed on the surface of the flange portion  91   b  through two-color molding. As shown in  FIG. 13 , the seal spring  92  is a coil spring having a conical shape in correspondence with to the outer contour of the tubular seat  86 . The shaft portion  91   a  of the movable valve  91  has a basal end inserted into a distal end portion of the seal spring  92  that has a small diameter. 
     A method for manufacturing the valve unit  22  by assembling the protection plate  39 , the pressure chamber component  36 , the first flow passage component  37 , and the second flow passage component  38  will now be discussed with reference to  FIGS. 14 to 19 . In  FIGS. 14 to 19 , the reference characters associated with the detailed parts of each component (e.g., first flow passage component  37 ) are omitted to simplify the drawings. 
     As shown in  FIGS. 14 to 19 , when assembling the valve unit  22  in a stacked state, an assembly jig  100 , screw members  101  serving as pressure contact members, and an adhesive (not shown) are used. The assembly jig  100  includes a planar base plate  100   a . A plurality of (two in the present embodiment) positioning rods  100   b  project from the upper surface of the base plate  100   a  at a fixed interval. The interval between the positioning rods  100   b  corresponds to the interval between the pairs of pilot holes  39   a ,  58 ,  81 , and  90  respectively formed on the protection plate  39 , the pressure chamber component  36 , the first flow passage component  37 , and the second flow passage component  38 . 
     When assembling the components together on the base plate  100   a  of the jig  100  in a stacked state, the protection plate  39  is arranged at the bottom. Then the pressure chamber component  36 , the first flow passage component  37 , and the second flow passage component  38  are stacked on top of each other, as shown in  FIG. 14 . The protection plate  39 , the pressure chamber component  36 , the first flow passage component  37 , and the second flow passage component  38  are stacked upside down so that the front surfaces face downward and the rear surface face upward. 
     First, the protection plate  39  is mounted on the base plate  100   a  of the jig  100  with the front surface facing downward, as shown in  FIG. 15 . In this state, the two positioning rods  100   b  formed on the base plate  100   a  are inserted into the pilot holes  39   a  of the protection plate  39 . This positions the protection plate  39  on the base plate  100   a  with the cylindrical bushings  41  facing upward and movement in the horizontal direction being restricted. The barrier film  49  is thermally welded to the front surface of the protection plate  39  in advance. 
     The seal film  44  is then attached to the rear surface, which is facing upward, of the protection plate  39 . Among the four cylindrical bushings  41  projecting from the rear surface of the protection plate  39 , the two cylindrical bushings  41  spaced by a short interval are inserted into the positioning holes  46  of the seal film  44 . This arranges the seal film  44  at a proper position so as to cover the conduit recesses  42  formed in the rear surface of the protection plate  39 . The seal film  44  is thermally welded to the protection plate  39  with the regions of the seal film  44  that are dome-shape and curved through pressure molding being located in the conduit recesses  42 . The seal film  44  may be attached to the rear surface of the protection plate  39  in advance. 
     Subsequently, the pressure chamber component  36  is arranged on the protection plate  39  with the front surface facing downward, as shown in  FIG. 16 . The elastic plate  62  is attached to the front surface of the pressure chamber component  36  in advance. Adhesive is applied to the adhesive application portion  36   a  of the front surface of the pressure chamber component  36 . The pressure chamber component  36 , to which adhesive is applied, is stacked on the rear surface of the protection plate  39 . At the same time, the two positioning rods  100   b  of the jig  100  is inserted into the corresponding pilot holes  58  of the pressure chamber component  36 . 
     As a result, the cylindrical bushings  41  of the protection plate  39  are inserted into the corresponding cutaway portions  55  and insertion holes  57  of the pressure chamber component  36 , and the seat  53  of the pressure chamber component  36  is fitted into the cutaway portion  40  of the protection plate  39 . The atmospheric communication hole  59  of the pressure chamber component  36  is in communication with the corresponding atmospheric communication hole  48  of the protection plate  39 . In this state, the adhesive application portion  36   a  of the pressure chamber component  36  is arranged at the proper position at which the adhesive application portion  36   a  is aligned with the adhering region (region around the conduit recesses  42  (not shown)) of the seal film  44  attached to the protection plate  39 . 
     The first flow passage component  37  is then arranged on the pressure chamber component  36  with the front surface facing downward, as shown in  FIG. 17 . The inlet filter members  74  are attached in advance to the recesses  70  to  73  of the first flow passage component  37 . Hexagonal nuts (not shown) are fitted in advance to the nut receptacles  36   c  of the rear surface, which is facing upward, of the pressure chamber component  36 . Adhesive is applied to the adhesive application portion  37   a  of the front surface of the first flow passage component  37 . The first flow passage component  37 , to which adhesive is applied, is stacked on the rear surface of the pressure chamber component  36 . At the same time, the two positioning rods  100   b  of the jig  100  is inserted into the corresponding pilot holes  81  of the first flow passage component  37 . 
     The threaded insertion holes  79  and  80  of the first flow passage component  37  are aligned with the threaded holes  41   a  of the corresponding cylindrical bushings  41  of the protection plate  39 , and the threaded insertion holes  37   b  are aligned with the corresponding nut receptacles  36   c  of the pressure chamber component  36 . The recesses  70  to  73  and the ink flow passages  76   a  to  76   c  of the first flow passage component  37  are aligned with the corresponding recesses  66  to  69  and the ink flow passages  65   a  to  65   c  of the pressure chamber component  36 , and the valve receptacles  78  of the first flow passage component  37  is aligned with the corresponding valve receptacles  64  of the pressure chamber component  36 . In this state, the adhesive application portion  37   a  of the front surface of the first flow passage component  37  is arranged at a proper position in alignment with the adhered region  36   b  of the pressure chamber component  36 . 
     As shown in  FIG. 18 , the movable valves  91  and seal springs  92  are inserted to the corresponding valve receptacles  78  of the first flow passage component  37 . Specifically, the shaft portion  91   a  of each movable valve  91  is first inserted to an entrance  51  of the pressure chamber component  36 , and the flange portion  91   b  is inserted to the valve receptacle  64  of the pressure chamber component  36 . Furthermore, the seal portion  91   c  is abut against the inner bottom surface of the valve receptacle  64  of the pressure chamber component  36 . The seal spring  92  is then inserted into the valve receptacle  78  of the first flow passage component  37  such that the basal end of the shaft portion  91   a  of the movable valve  91  is inserted into the seal spring  92  at the distal end portion having a small diameter. 
     Thereafter, the second flow passage component  38  is arranged on the first flow passage component  37  with the front surface facing downward, as shown in  FIG. 19 . The outlet filter members  85  are attached in advance to the recesses  83  of the second flow passage component  38 . The adhesive is applied to the adhesive application portion  38   a  of the front surface of the second flow passage component  38 . The second flow passage component  38 , to which adhesive is applied, is stacked on the rear surface of the first flow passage component  37 . At the same time, the positioning rods  100   b  of the jig  100  are inserted to the corresponding pilot holes  90  of the second flow passage component  38 . 
     The threaded insertion holes  88 ,  89 ,  38   b  of the second flow passage component  38  are thereby positioned with the corresponding threaded insertion holes  79 ,  80 ,  37   b  of the first flow passage component  37 , and each recess  83  and each ink flow passage  87  are positioned with the corresponding concave part (not shown) and the ink flow passage (not shown) of the first flow passage component  37 . Furthermore, the tubular seat  86  of the second flow passage component  38  is inserted to the corresponding valve receptacle  78  of the first flow passage component  37 , and the distal end of the tubular seat  86  is inserted to the basal end portion having a large diameter of the seal spring  92  that is already inserted in the valve receptacle  78 . In this state, the adhesive application portion  38   a  of the front surface of the second flow passage component  38  is arranged at an appropriate position at where the adhesive application portion  38   a  is positioned with the adhering region (not shown) formed on the rear surface of the first flow passage component  37 . 
     A plurality of (four in the present embodiment) screw members  101  are inserted into the threaded insertion holes  88  and  89  of the second flow passage component  38 , as shown in  FIG. 19 . The distal ends of the screw members  101  are extended through the corresponding threaded insertion holes  79  and  80  of the first flow passage component  37  and fastened to the threaded holes  41   a  of the corresponding cylindrical bushings  41  on the protection plate  39 . The fastening force of the screw members  101  hold the flow passage formation bodies (the pressure chamber component  36 , first flow passage component  37 , and second flow passage component  38 ) with the protection plate  39  in a clamped state with adhesive applied between the flow passage formation bodies that are adjacent to each other in the stacking direction. 
     The adhesive between the adjacent flow passage formation bodies dry and harden while the adjacent flow passage formation bodies (e.g., first flow passage component  37  and second flow passage component  38 ) are clamped in the stacking direction. Thus, the manufacturing of the valve unit  22  is completed without waiting for the adhesive to dry and harden. 
     A head case  102  of the recording head  13  is then integrated with the completed valve unit  22 . A head connection port rubber seal  103 , a peripheral rubber seal  104 , and a head base plate  105  are arranged on the rear surface of the valve unit  22 , and the head case  102  is attached to the rear surface of the second flow passage component  38  from which the head connection ports  22   a  project, as shown in  FIG. 20 . At the same time, fastening screws  107  are inserted to a plurality of (three in the present embodiment) threaded holes  106  formed in the head case  102 . 
     The distal ends of the fastening screws  107  are then extended through the threaded insertion holes  38   b  of the second flow passage component  38  and the threaded insertion holes  37   b  of the first flow passage component  37  and fastened to the hexagonal nuts (not shown) fitted into the nut receptacle  36   c  of the pressure chamber component  36 . The head case  102  is fixed to the valve unit  22  by the fastening force of the fastening screws  107 . This completes the head unit  108  shown in  FIG. 21 . 
     This manufactures the valve unit  22  including a plurality of liquid supply passages capable of supplying ink from the plurality of ink cartridges  16  to the recording head  13  with the plurality of nozzle rows  13 A corresponding to the ink cartridges  16 . In the present embodiment, the liquid supply passages in the valve unit  22  is formed by the conduit flow passages  50  (pressure chamber  50 A), the ink flow passages  65   a  to  65   c ,  76   a  to  76   c , and  87 , and the recesses  66  to  69 ,  70  to  73 , and  83 . 
     Each liquid supply passage includes a common portion (e.g., conduit flow passage  50  (pressure chamber  50 A), ink flow passage  76   a , recesses  70  to  73  etc.) that are functionally in common with other liquid supply passages in the valve unit  22  of the present embodiment. The common portion of the plurality of liquid supply passages is formed in the same flow passage formation body (e.g., pressure chamber component  36 , second flow passage component  38 ). Therefore, pressure fluctuations do not differ between the pressure chambers  50 A in the plurality of liquid supply passages. The head unit  108  (valve unit  22 ) manufactured in this manner is then mounted on the carriage  14 . 
     The operation of the head unit  108  will now be described with reference to  FIG. 22 .  FIG. 22  is a schematic diagram simply showing the ink supply state in the head unit  108 , particularly, in the valve unit  22 . Detailed parts of the valve unit  22  are partially omitted. 
     The ink supplied to the valve unit  22  through each ink supply tube  23  is temporarily stored in the pressure chamber  50 A. Then, the ink is supplied to the corresponding nozzle row  13 A (see  FIG. 20 ) of the recording head  13  and ejected from the nozzle  13   a . In a state in which ink is temporarily stored in the pressure chamber  50 A, if ink flows out of the pressure chamber  50 A into the recording head  13  via the exits  52  as ink is ejected from the nozzles  13   a , pressure fluctuation (i.e., negative pressure) occurs in the pressure chamber  50 A. 
     As a result, the seal film  44  is displaced so as to deform inward (downward in  FIG. 2 ) into the pressure chamber  50 A due to the generated negative pressure. This pushes the elastic strip (actuating lever)  60  into the pressure chamber  50 A. Consequently, the elastic strip  60  pushes the movable valve  91 , which is located at the valve close position shown in  FIG. 22 , downward (i.e., direction towards valve open position) against the urging force of the seal spring  92  to open the valve with actuation force obtained by increasing the displacement force of the seal film  44 . As a result, the movable valve  91  opens the entrance  51  of the pressure chamber  50 A, and ink flows into the pressure chamber  50 A from the ink flow passages  65   a ,  65   b ,  76   a , and  76   b , which form part of the liquid supply passage in the valve unit  22 , through the entrance  51 . 
     The flow of the entering ink increases the pressure in the pressure chamber  50 A and cancels the negative pressure state. Thus, the seal film  44  returns to its original form as shown in the state of  FIG. 22 . The elastic strip  60  also returns to its original form as shown in the state of  FIG. 22 . This moves the movable valve  91  again to the valve close position for closing the entrance  51  with the urging force of the seal spring  92 . Accordingly, the flow of ink from the entrance  51  into the pressure chamber  50 A is restricted. 
     If foreign matter is contained in the ink supplied from the ink supply tube  23  to the valve unit  22 , such foreign matter is first captured by the inlet filter member  74 . As a result, foreign matter does not reach the downstream side of the inlet filter member  74 , and foreign matter is prevented from being caught in the seal portion  91   c  of the movable valve  91  and affecting sealing properties. Further, the temporary storage of ink and the supply of ink to the recording head  13  are performed while maintaining the environment in the pressure chamber  50 A clean. 
     Fine foreign matter (e.g., less than 29 microns) that cannot be captured by the inlet filter member  74  passes through the movable valve  91  and reaches the pressure chamber  50 A. However, such fine foreign material is captured by the outlet filter member  85  located downstream of the pressure chamber  50 A. This prevents the nozzle  13   a  from being clogged by foreign matter. 
     Foreign matter may enter the head case  102  of the recording head  13  during the manufacturing stage. When such foreign matter is suspended in the ink supplied from the valve unit  22  to each nozzle row  13 A through an ink flow passage (liquid supply passage), which is not shown in the drawings, in the head case  102 , such foreign matter would clog the nozzles  13   a . In such as case, the fastening screws  107  are removed to separate the head case  102  from the valve unit  22  in the present embodiment. Then, the ink flow passage in the head case  102  undergoes forcibly suction from the side opposite the nozzle  13   a  of the recording head  13 , that is, from the upstream side in the ink flow direction, to reverse the flow of ink and reversely wash the recording head  13 . A filter member is not arranged in the ink flow passage in the head case  102 . This ensures that the foreign matter is discharged from the head case  102  with the ink reversely flowing through the ink flow passage when the above washing is performed. 
     The above embodiment has the advantages described below. 
     (1) The valve unit  22  supplies the ink from the plurality of ink cartridges  16  to the corresponding nozzle row  13 A via the plurality of liquid supply passages corresponding to the plurality of ink cartridges  16 . Each liquid supply passage includes a common portion (e.g., conduit flow passage  50  (pressure chamber  50 A), ink flow passage  76   a , recesses  70  to  73  etc.) that is functionally in common with other liquid supply passages. The common portion of the plurality of liquid supply passages is formed in the same flow passage formation body (e.g., pressure chamber component  36  and second flow passage component  38 ). This prevents the ink supplying function from varying between the liquid supply passages (e.g., between the pressure chambers  50 A), and the ink supplying state becomes uniform. 
     (2) The plurality of pressure chambers (liquid storage unit)  50 A, each forming part of a liquid supply passage, are formed in the same pressure chamber component (flow passage formation body)  36  and identically shaped. Thus, pressure fluctuations, which occur in the pressure chamber  50 A when ink is ejected from the nozzle row  13 A of the recording head  13 , does not vary between the plurality of pressure chambers  50 A. Accordingly, the state of the ink flowing out of the plurality of pressure chambers  50 A to the recording head  13  is uniform. 
     (3) The plurality of pressure chambers  50 A are formed by the plurality of conduit flow passages  50  extending parallel to each other. Thus, the plurality of pressure chambers  50 A are formed in the same flow passage formation body (pressure chamber component  36  in the present embodiment) while saving space. This contributes to the miniaturization of the printer  10  compared to when the flow passage forming the pressure chamber is a circular flow passage or the like. 
     (4) The plurality of pressure chambers (liquid storage unit)  50 A may be formed simultaneously just by covering the plurality of conduit flow passages  50  formed in the pressure chamber component  36 , which is one of the flow passage formation bodies, with a single seal film  44 . Therefore, the manufacturing efficiency of the valve unit  22  is improved compared to when using a strip of a seal film for each conduit flow passage  50 . 
     (5) The movable valve (open/close valve)  91  is arranged at each entrance  51  of the plurality of pressure chambers  50 A. However, the seal film  44  displaced to open the movable valve  91  is a single film member used commonly between each of the movable valves  91 . Thus, the operation timing is prevented from varying between the plurality of movable valves  91 . This aspect also contributes to making the state of the ink flowing out of the plurality of pressure chambers  50 A to the recording head  13  uniform. 
     (6) The plurality of actuating levers for operating each of the plurality of movable valves  91  is formed by a plurality of elastic strips  60  extending from the single elastic plate  62 . That is, the plurality of actuating levers corresponding to the plurality of movable valves  91  is prepared by simply attaching the single elastic member  62  to the pressure chamber component  36 . This improves the manufacturing efficiency of the valve unit  22 . 
     (7) The state of the ink supplied from the plurality of liquid supply passages (e.g., pressure chamber  50 A) to the nozzle row  13 A of the recording head  13  is uniformed. Thus, the state of the ink ejected from the plurality of nozzle rows  13 A is prevented from varying between the nozzle rows  13 A. 
     (8) Even if the adhesive between adjacent flow passage formation bodies is still not dry, the subsequent flow passage formation bodies can be adhered to each other one after another. That is, the screw member  101  serving as the pressure contact member holds the flow passage formation bodies so that they are not displaced or separated even if the adhesive is still not dried and hardened. Accordingly, the assembly of the valve unit  22  may be quickly completed without waiting for the adhesive to dry and harden. This improves the manufacturing efficiency of the printer  10  incorporating the valve unit  22 . 
     (9) The plurality of flow passage formation bodies is rapidly and easily integrated by using the screw members  101 , which are versatile products, in the manufacturing stage of the valve unit  22 . The state of pressure contact between adjacent flow passage formation bodies is adjusted by adjusting the fastening force of the screw members  101 . 
     (10) The integration of the flow passage formation bodies is completed by simply fastening the screw members  101  once even if there are many flow passage formation bodies forming the valve unit  22 . This improves the manufacturing efficiency of the valve unit  22 . 
     (11) The flow passage formation bodies adjacent in the stacking direction, such as the pressure chamber component  36  and the first flow passage component  37 , are stacked in a satisfactory manner so that the outer contours are aligned when viewed from above by using the positioning function of the pilot holes  58  and  81  serving as the positioning portions. 
     (12) When the ink supplied from the valve unit  22  to the recording head  13  contains foreign matter, such foreign matter is captured by the outlet filter member  85  arranged in the liquid supply passage (recess  83 ) of in the valve unit  22 . Thus, ink from which foreign matter is eliminated is supplied from the valve unit  22  to the recording head  13 . If foreign matter is present in the ink flow passage (liquid supply passage) in the head case  102 , such foreign matter is removed by reversely washing the recording head  13 . 
     (13) If the ink supplied from the ink cartridge  16  to the valve unit  22  contains foreign matter, such foreign matter is captured and removed by the inlet filter member  74 . This keeps the environment in the valve unit  22  (pressure chamber  50 A etc.) clean. This reduces the possibility of foreign matter being caught in the seal portion  91   c  of the movable valve (open/close valve)  91 , and the sealing function remains the same. Thus, the operation of the valve unit  22  is stabilized. 
     (14) Foreign matter that cannot be captured by the inlet filter member  74  is captured by the outlet filter member  85  arranged on the downstream side of the inlet filter member  74 . Thus, clean ink, from which foreign matter is eliminated, is supplied to the recording head  13 . 
     (15) The mesh roughness of the outlet filter member  85  is set so as to enable the capturing of foreign matter smaller than the diameter of the nozzles  13   a  of the recording head  13 . This prevents the nozzles  13   a  from being clogged by foreign matter. 
     (16) Each of the filter members  74  and  85  is attached to one of the flow passage formation bodies at a predetermined location (recess  70  to  73 ,  83 ) before stacking the flow passage formation bodies. Accordingly, the attachment of the filter members  74  and  85  is significantly simplified. 
     The above embodiment may be modified to different embodiments as described below. 
     In the above embodiment, each of the filter members  74  and  85  may be press-fitted to and attached to the liquid inlets  54  or the liquid outlets  84  in the valve unit  22 . 
     In the above embodiment, the mesh roughness of each of the inlet filter members  74  and the outlet filter members  85  may be the same. Alternately, the mesh roughness may have any value differing from that of the above embodiment (29 microns, 19 microns). 
     In the above embodiment, instead of metal mesh, each of the filter members  74  and  85  may be made of non-woven cloth, glass fiber, or the like. 
     In the above embodiment, the inlet filter members  74  may be eliminated from the valve unit  22  so that only the outlet filter members  85  are attached to the valve unit  22 . In this case, foreign material can be eliminated from the inside of the recording head  13  by reversely washing the recording head  13 . 
     In the above embodiment, the protection plate  39 , the pressure chamber component  36 , the first flow passage component  37 , and the second flow passage component  38  may each be divided into four flow passages. Each of the quarterly-divided flow passage formation body may be stacked to form units of single flow passages, thereby forming four valve units. In such a structure, the valve unit can be readily manufactured in units of single flow passages without waiting for the adhesive to dry and harden. 
     In the above embodiment, the pilot holes  39   a ,  58 ,  81  serving as the positioning portions do not necessarily need to be arranged in the valve unit  22 . 
     In the above embodiment, the screw members  101 , serving as the pressure contact members may hold only two of the flow passage formation bodies that are adjacent in the stacking direction in a clamped state with the screw fastening force. In this case, however, the screw member  101  that becomes necessary increases as the number of flow passage formation bodies that are stacked increases. 
     In the above embodiment, the pressure contact member may be a clip device or a pressing device in lieu of the screw members  101 . 
     In the above embodiment, the plurality of elastic strips  60  forming the actuating levers may each be an elastic member of a simple structure. 
     In the above embodiment, the elastic plate  62  may be eliminated, and a pressure receiving plate may be attached to the seal film  44  so that the pressure receiving plate opens the movable valve  91  when the seal film  44  is displaced. 
     In the above embodiment, the seal film  44  may be a plurality of film strips respectively corresponding to the plurality of conduit recesses  42 . 
     In the above embodiment, the flow passage of the valve unit  22  forming the pressure chamber  50 A is not limited to the conduit flow passages  50  and may be a circular hole. 
     The valve unit  22  does not necessarily need to be formed by stacking the plurality of flow passage formation bodies as long as the common portion of the plurality of the liquid supply passages is formed in the same flow passage formation body, and the valve unit  22  may be formed by a single flow passage formation body. 
     A printer (printing device including facsimile, copier etc.) for ejecting ink has been described as the liquid ejection apparatus in the above embodiment. However, the printer may be a liquid ejection apparatus that ejects other liquids. The liquid ejection apparatus according to the present invention may be applied to an apparatus for manufacturing a liquid crystal display, plasma display, organic EL display, an FED (field emission display), or the like. The liquid ejection apparatus discharges various materials such as a coloring material for forming a pixel forming region, electrode forming region, or the like or liquid for an electrode or the like. The liquid ejection apparatus of the present invention may be applied to a liquid ejection apparatus for ejecting liquid containing bioorganic substance used in manufacturing bio chips.