Patent Publication Number: US-2009225142-A1

Title: Liquid ejection head, method for manufactuirng the same, and liquid ejecting apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejection head ejecting liquid, a method for manufacturing the same, and a liquid ejecting apparatus including the liquid ejection head, and specifically to an ink jet recording head ejecting ink as liquid, a method for manufacturing the same, and an ink jet recording apparatus. 
     2. Related Art 
     In an ink jet recording head, which is a representative of liquid ejection heads, in general, ink is supplied to a head body from an ink cartridge or a liquid reservoir containing the ink through an ink supplier such as an ink supply needle removably inserted in the ink cartridge and an ink flow channel formed in a supply member, such as a cartridge case holding the ink cartridge. The ink supplied to the head body is ejected from a nozzle by operating a pressure generator, such as a piezoelectric element, provided to the head body. 
     However, the cartridge contains air with the ink, and when the cartridge is removed from or attached to the head, air may be trapped in the ink. Such air can be delivered to the head body and undesirably cause ejection failure such as dot missing. In order to overcome this problem, for example, Japanese Unexamined Patent Application Publication No. 2000-211130 discloses a head including a filter. The filter is disposed between the ink supply needle inserted into the ink cartridge and the supply member to remove air and foreign matter from the ink. 
     The filter and the supply member are fixed to each other by thermal welding or the like, and the ink supply needle and the supply member are fixed to each other by ultrasonic welding or the like. 
     In the structure disclosed in the above-cited patent document, the filter is fixed to the supply member in a region where the ink supply needle is fixed. Accordingly, the supply member requires an area used for fixing the filter according to the area of the filter, and also requires other areas where the ink supply needle and the filter are welded. It is therefore difficult to reduce the intervals between the ink supply needles, and accordingly the head becomes large. 
     In addition, if the area of the filter is excessively reduced to miniaturize the head having the structure disclosed in the above cited patent document, the driving voltage for driving the pressure generator, such as a piezoelectric element or a heating element, must be increased undesirably because of the increase of dynamic pressure. 
     In the structure in which the ink supply needle and the supply member are fixed by, for example, thermal welding, a gap may be formed between the ink supply needle and the supply member, and thus the ink may leak from the gap. The structure in which the filter and the ink supply needle are fixed to the supply member in different process steps leads to an increased cost. 
     A filter may be provided across a plurality of flow channels. This structure makes the handling easier than the case in which a plurality of filters are provided for respective flow channels. However, liquids running through the plurality of flow channels may be undesirably mixed. 
     These problems can arise not only in the ink jet recording head, but also in the liquid ejection head ejecting liquid other than ink. 
     SUMMARY 
     An advantage of some aspects of the invention is that it provides a liquid ejection head having a structure in which liquids running through a plurality of flow channels are not mixed together even though a filter is provided across the plurality of flow channels, a method for manufacturing the liquid ejection head, and a liquid ejecting apparatus including the liquid ejection head. 
     According to an aspect of the invention, a liquid ejection head is provided which ejects a liquid contained in a liquid reservoir from nozzle apertures through a plurality of liquid supply channels. The liquid ejection head includes a first liquid supply member and a second liquid supply member that define the plurality of liquid supply channels, and a filter disposed between the first supply member and the second supply member. The filter includes a plurality of filter portions corresponding to the respective liquid supply channels, and at least one joining portion disposed across the region between the filter portions to join the filter portions to each other. The first supply member and the second supply member are bonded together at a region thereof corresponding to the joining portion of the filter with a resin joint that is made of a resin penetrating the joining portion. 
     The first and the second supply member and the joining portion of the filter are joined into one body with the resin joint. Thus, no region is required for welding the filter to the first supply member and the second supply member. Consequently, the effective area of the filter can be increased and the interval between the suppliers can be reduced. In addition, since the resin penetrating the joining portion between the flow channels seals the filter portions, the liquid ejection head can be miniaturized without mixing the liquids running through the plurality of flow channels even though the filter extends across the plurality of flow channels. In addition, it is not required that the effective area of the filter be reduced to miniaturize the head. It is accordingly not required that the driving voltage of the piezoelectric element be increased while the dynamic pressure is prevented from increasing. Furthermore, since the resin penetrates the joining portion of the filter, the regions between the liquid supply channels can be reliably sealed to prevent liquids from leaking between the flow channels. 
     Preferably, the first supply member and the second supply member each have a recess in a region opposing at least part of the joining portion, and the resin joint is formed by filling the recesses with the resin to integrate the first supply member and the second supply member together. Since the resin fills the recesses surrounding the joining portion of the filter, the filter can be reliably secured. 
     Preferably, the filter portions have fine pores, and the joining portion has a through hole having a larger diameter than the pores of the filter portions. This facilitates the penetration of the resin into the joining portion. Consequently, the filter, the first supply member and the second supply member are integrated together with reliability. 
     Preferably, the joining portion has a smaller width than the filter portions. Thus, the resin joint is formed so as to surround the joining portion to integrate the filter, the first supply member, and the second supply member with reliability. 
     Preferably, the first supply member and the second supply member have respective filter holding portions opposing each other and are in contact with the filter so as to surround the liquid supply channels. The filter portions have a shape corresponding to the outline of the filter holding portions. The resin fills the region outside the filter holding portions between the first supply member and the second supply member continuously from the resin joint, thus joining the first supply member and the second supply member together. Thus, the periphery of the filter is covered with the resin with a minimum area of the outer edge of the filter. Consequently, the liquid does not leak from a gap between the first supply member and the second supply member. 
     Preferably, the liquid ejection head further includes an outer portion around the first supply member, the second supply member and the filter. The outer portion is made of the same resin as the resin joint and continues to the resin joint. The outer portion joins the first supply member and the second supply member together. Since the first supply member and the second supply member are reliably joined with the outer portion, the liquids do not leak from the gap between the first supply member and the second supply member. 
     According to another aspect of the invention, a liquid ejection apparatus including the above-described liquid ejection head is provided. The liquid ejection apparatus can be small and manufactured in a low cost. 
     According to still another aspect of the invention, a method for manufacturing the liquid ejection head is provided. In the method, the first supply member and the second supply member are placed in a mold with the filter held therebetween. Then, a resin joint is formed by introducing a resin into a region corresponding to the joining portion between the first supply member and the second supply member so that the resin penetrates the joining portion of the filter to join the first supply member and the second supply member together. 
     In this instance, the resin penetrating the joining portion of the filter integrates the first supply member and the second supply member. Accordingly, no region is required to weld the first supply member and the second supply member to the filter. Consequently, the effective area of the filter can be increased and the interval between the suppliers can be reduced. Thus, the head can be miniaturized. In addition, it is not required that the area of the filter be reduced to miniaturize the head. It is accordingly not required that the driving voltage of the piezoelectric element be increased while the dynamic pressure is prevented from increasing. Furthermore, since the resin penetrates the joining portion of the filter, the region between the liquid supply channels can be more reliably sealed to prevent liquids from leaking between the flow channels. 
     Preferably, either the first supply member or the second supply member has a filling hole in a region thereof corresponding to the joining portion. The resin is introduced through the filling hole. The mold has a cavity surrounding the joining portion and a gate communicating with the cavity. Thus, the resin introduced from the gate through the filling hole can more easily penetrate the joining portion and thus more reliably seals the region between the liquid supply channels. Consequently, the liquids can be prevented from leaking between the flow channels with reliability. 
    
    
     
       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 schematic perspective view of a recording apparatus according to a first embodiment of the invention. 
         FIG. 2  is an exploded perspective view of a recording head according to the first embodiment of the invention. 
         FIG. 3  is a top view of a supply member of the recording head according to the first embodiment. 
         FIG. 4A  is a plan view of a filter used in the supply member and  FIG. 4B  is a fragmentary enlarged top view of an essential part of the supply member shown in  FIG. 3 . 
         FIG. 5  is a sectional view of the supply member of the liquid ejection head according to the first embodiment. 
         FIG. 6  is a sectional view showing a method for preparing the supply member according to the first embodiment. 
         FIG. 7  is a sectional view showing the method for preparing the supply member according to the first embodiment. 
         FIG. 8  is an exploded perspective view of a head body of the recording head according to the first embodiment. 
         FIG. 9  is a sectional view of the head body shown in  FIG. 8 . 
         FIG. 10  is a sectional view of a supply member according to a second embodiment of the invention. 
         FIG. 11  is a sectional view of a filter according to the second embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The invention will further be described with reference to exemplary embodiments. 
     First Embodiment 
       FIG. 1  is a schematic perspective view of an ink jet recording apparatus, which is a type of the liquid ejecting apparatus according to the first embodiment of the invention. The ink jet recording apparatus  10  of the first embodiment includes an ink jet recording head (hereinafter may be referred to as the recording head)  11  that is a liquid ejection head ejecting ink droplets. The recording head  11  is fixed to a carriage  12 , and to which ink cartridges  13 , or liquid reservoirs, are removably secured, as shown in  FIG. 1 . The ink cartridges  13  respectively contain a plurality of colors including black (B), light black (LB), cyan (C), magenta (M), and yellow (Y). 
     The carriage  12  having the recording head  11  is secured to a carriage shaft  15  fixed to the device body  14  and is movable along the shaft. The carriage  12  is moved along the carriage shaft  15  by transmitting the driving force from a driving motor  16  to the carriage  12  with a plurality of gears (not shown) and a timing belt  17 . In the apparatus body  14 , platen  18  is disposed along the carriage shaft  15  so that print medium S, such as paper, fed from a paper feed unit (not shown) or the like is transported over the platen  18 . 
     A capping unit  20  having a cap member  19  sealing the nozzle region of the recording head  11  is disposed at a position corresponding to the home position of the carriage  12 , that is, by one end of the carriage shaft  15 . The cap member  19  seals the nozzle region having nozzle apertures, thereby preventing the inks from drying. The cap member  19  also acts as an ink receiver for flushing operation. 
     The recording head  11  of the present embodiment will now be described.  FIG. 2  is an exploded perspective view of the ink jet recording head, which is a type of the liquid ejection head of the invention. 
     As shown in  FIG. 2 , the recording head  11  includes a supply member  30 , such as a cartridge case in which the ink cartridge  13  or liquid reservoir is fixed, a head body  220  fixed to the opposite surface to the ink cartridge  13  of the supply member  30 , and a cover head  240  provided at the liquid ejecting face of the head body  220 . 
     First, the supply member  30  will be described in detail.  FIG. 3  is a top view of the supply member;  FIGS. 4A and 4B  are a plan view of the filter and a fragmentary enlarged top view of the essential part of the supply member, respectively; and  FIG. 5  is a sectional view taken along line V-V in  FIG. 4B . 
     As shown in  FIG. 5 , the supply member  30  includes a first supply sub-member and a second supply sub-member with the filter therebetween. In the present embodiment, a supply member body  31  acting as either the first or the second sub-member is disposed at the downstream side of the flow channels, and supply needles  32  acting as the other supply sub-member oppose the supply member body  31 . The supply member body  31  and the supply needles  32  hold a filter therebetween and are integrated with an outer portion  34 . 
     The supply member  30  has a supplier section  35  in which the ink cartridges  13  (liquid reservoirs) are disposed. The ink cartridges  13  may not directly be disposed in the supplier section  35 , and liquid or ink may be delivered to the supplier section  35  through a tube from a liquid reservoir. 
     The supply member body  31  has liquid supply channels  36  downstream from the filter  33 . Both ends of each liquid supply channel  36  are open and respectively communicate with the supplier section  35  and the head body  220 , so that the liquid supply channel  36  can supplies the ink from the ink cartridge  13  to the head body  220 . The liquid supply channels  36  are arranged in the longitudinal direction of the supply member body  31 , and are independent from the ink cartridges  13  provided for respective colors. 
     The surface (supplier section  35 ) of the supply member body  31  acts as filter holding portions  37  in regions around the openings of the liquid supply channels  36 . The filter  33  is secured between the filter holding portions  37  and the supply needles  32 . The regions around the liquid supply channels  36  refer to surroundings adjacent to the openings of the liquid supply channels  36  and filter spaces  41 . Preferably, the filter holding portions  37  are as close as possible from the viewpoint of saving space. 
     The supply needles  32  acting as the supplier are fixed to the surface (supplier section  35 ) of the supply member body  31 , and each has a through-path communicating with the liquid supply channel  36  and thus acts as part of the liquid supply channel. The junction between the through-path  40  and the liquid supply channel  36  forms a space having a larger diameter than the other portions. This space is the filter space  41 . In the present embodiment, the diameter of the filter space  41  increases toward the supply member body  31 . The opening of the filter space  41  at the supply nozzle side acts as the liquid delivering hole. The ink is supplied from the ink cartridge  13  to the supply member body  31  through the liquid delivering hole. 
     Regions of the supply needles  32  surrounding the filter spaces  41  act as filter holding portions  42  at the bottom of the supply needle  32  at the supply member body side, and hold the filter  33  with the filter holding portions  37  of the supply member body  31 . 
     The filter  33 , held between the supply member body  31  and the supply needles  32 , is a sheet formed by finely interweaving a metal and has fine pores. In the present embodiment, the filter  33  has such a size that can be held between the filter holding portions  37  and  42  of the supply member body  31  and the supply needles  32 .  FIG. 4A  shows the external form of the filter  33 , and  FIG. 4B  shows the regions (regions A) of the filter  33  held between the filter holding portions  37  and  42 . The filter  33  has effective filter portions having a diameter substantially equal to the outer diameter of region A, which is slightly larger than the diameter of the liquid supply channel  36 . The effective filter regions are joined with a joining portion  43 . The joining portion  43  has a through hole  47  having a larger diameter than the pores of the filter. 
     The supply member body  31 , the supply needles  32 , and the filter  33  are provided with the outer portion  34  integrally formed by injection molding with the supply member body  31 , the supply needles  32 , and the filter  33  placed in a mold. The outer portion  34  is formed so as to surround the supply member body  31  and the supply needles  32  and reliably seal spaces formed by the outer edge of the filter  33  and the gaps between the supply member body  31  and the supply needles  32  and a region around the joining portion  43  of the filters  33 , with the through-paths  40  and the liquid supply channels  36  isolated, thereby integrating the supply member body  31 , the supply needles  32 , and the filter  33 . Thus, the outer portion  34  prevents the ink from leaking from the liquid supply channels  36 . 
     In the present embodiment, two supply needles  32  are integrated into one member for two liquid supply channels. Hence, five members are provided for 10 liquid supply channels  36  (not shown), as shown in  FIG. 3 . The regions of the supply member body  31  and the supply needles  32  corresponding to the joining portion  43  of the filter  33  have recesses. The recesses are filled with a resin to form a connecting portion  45 . The connecting portion  45  continues to the outer portion  34  and surrounds the joining portion  43  of the filters  33 . The connecting portion  45  has a filling hole  46  communicating with a gate through which the resin of the outer portion  34  is introduced. 
     In the present invention, a single filter  33  is disposed so as to continue across the two liquid supply channels  36 . Therefore, a through hole  47  is formed in the region of the joining portion  43  of the filter  33  corresponding to the filling hole  46  so that the resin introduced through the filling hole  46  can reach and fill the outer portion  34  with reliability. The through hole  47  of course may not be formed. A filter  33  may be provided for each of the ten liquid supply channels  36  and the plurality of filters  33  may be joined into one piece. 
     The resin delivered through the filling hole  46  penetrates the joining portion  43  of the filter  33  and is introduced to the rear side of the filter  33  through the through hole  47  to form the connecting portion  45 . The connecting portion  45  is integrated with the supply member body  31  and the supply needles  32  in their recesses, thus acting as a resin joint that integrates the filter  33 , the supply member body  31  and the supply needles  32  together. The resin delivered through the filling hole  46  further fills regions around the supply member body  31  and supply needles  32  to form the outer portion  34 . 
     Thus, the connecting portion  45  reliably seals the region between the liquid supply channels  36  to prevent liquids from being mixed and integrates the supply member body  31 , the supply needles  32  and the filter  33 . In addition, since the outer portion  34  continues to the connecting portion  45 , the supply member body  31 , the supply needles  32  and the filter  33  are more reliably integrated. 
     The filter  33  of the present embodiment has such a size that can be held between the filter holding portions  37  and  42  around the liquid supply channels  36 , as described above. The resin penetrates around the filter  33  along the periphery of the filter  33 , thus forming the outer portion  34 . Thus, the outer portion  34  further reliably integrates the supply member body  31 , the supply needles  32  and the filter  33  together, thereby reliably sealing the periphery of the filter  33  with resin. 
     As described above, the connecting portion  45  and the outer portion  34  ensure the integration of the supply member body  31 , the supply needles  32  and the filter  33 , and thus the supply member  30  is formed in a single body. BY integrating the supply member body  31 , the supply needles  32  and the filter  33  with the integrated connecting portion  45  and outer portion  34 , no region is required for welding the supply needles  32  and the filter  33  to the supply member body  31 . Consequently, the interval between the supply needles  32  can be reduced, and the liquids flowing adjacent liquid supply channels can be prevented from leaking. Thus, the head can be miniaturized. In addition, it is not required that the area of the filter  33  be reduced to miniaturize the head. It is accordingly not required that the driving voltage of the piezoelectric element  300  be increased while the dynamic pressure is prevented from increasing. 
     Since the connecting portion  45  and the outer portion  34  can simultaneously fix the filter  33  and the supply needles  32  to the supply member body  31 , there is no need to fix the filter  33  and the supply needles  32  to the supply member body  31  in different process steps. Consequently, the manufacturing cost can be reduced. 
     Furthermore, since the supply member body  31 , the supply needles  32  and the filter  33  can be reliably secured with the connecting portion  45  and the outer portion  34 , gaps are not formed between the supply member body  31  and the supply needles  32 . Consequently ink leakage can be prevented. 
     The outer portion  34  is not necessarily required. In order to seal the liquid supply channels  36  from each other by simultaneously fixing the filter  33  and the supply needles  32  to the supply member body  31 , only the connecting portion  45  may be provided. Even though the outer portion  34  is provided, the outline of the filter  33  may be the same or slightly larger than that of the supply member body  31  and supply needless  32  without being limited to the embodiment. 
     The method for manufacturing the ink jet recording head  11 , particularly for preparing the supply member  30 , will now be described.  FIGS. 6 and 7  are sectional views showing the method for preparing the supply member. 
     First, the filter  33  is held between the supply member body  31  and the supply needles  32 , as shown in  FIG. 6 . More specifically, the filter  33  held between the filter holding portion  37  of the supply member body  31  and the filter holding portion  42  of the supply needles  32  is placed in a mold  200 . In this instance, the supply member body  31  and the supply needles  32  may be independently prepared and then placed in the mold  200 , or may be formed in the mold  200  and subsequently subjected to the above integration. 
     The mold  200  includes an upper member and a lower member, and has cavities  201  and  202  in which the connecting portion  45  and the outer portion  34  are formed, and a gate  203  communicating with the cavity  201 . 
     Then, a resin is introduced through the gate  203  to fill the cavities  201  and  202 , thus integrally forming the outer portion  34  to complete the supply member  30 , as shown in  FIG. 7 . More specifically, a molten resin is introduced through the gate  203  to fill the cavities  201 . The resin penetrates the junction portion  43  of the filter  33  and flows through the through hole  47  to fill the cavity  201 , thus forming the connecting portion  45 . The resin also flows from the cavity  201  along the periphery of the filter  33  between the supply member body  31  and the supply needles and thus fills the cavity  202  to form the outer portion  34 . 
     Thus, the filter  33  is joined and integrated with the supply member body  31  and the supply needles  32  with the connecting portion  45 . Consequently, the region between the liquid supply channels  36  can be reliably sealed. The outer portion  34  extends over the entire region around the supply member body  31  and supply needles  32 . Consequently, the supply member body  31 , the supply needles  32  and the filter are joined into one body. 
     The filter  33  has the through hole  47 , as described above. The through hole  47  allows the fused resin to pass therethrough and helps the resin easily flow in the vertical direction in the cavity  201  of the mold  200 , and thus facilitates the introduction of the resin into the mold  200 . 
     The supply member  30  does not require different process steps for welding the filter  33  and the supply needles  32  to the supply member body  31 , and allows the supply member body  31 , the supply needles  32  and the filter to be integrated together by a single step integrally forming the outer portion  34  with those parts. Thus, the manufacturing process can be simplified to reduce the cost. 
     The head body  220  is disposed at the other side of the liquid supply channels  36  of the supply member  30 , that is, at the opposite side to the supply needles  32 . The head body  220  will now be described.  FIG. 8  is an exploded perspective view of the head body and  FIG. 9  is a sectional view of the head body. 
     As shown in these figures, the head body  220  includes a monocrystalline silicon flow channel substrate  60  and a silicon dioxide elastic film  50  on one surface of the flow channel substrate  60 . The flow channel substrate  60  has pressure generating chambers  62  separated by a plurality of partition members. The pressure generating chambers  62  are formed by anisotropic etching of the flow channel substrate  60 , and are arranged in two lines parallel to each other in the width direction of the head body  220 . A communicating section  63  is formed to the outside of the pressure generating chambers  62  in the longitudinal direction of the pressure generating chambers  62 . The communicating section  63  communicates with a reservoir section  81  formed in a below-described reservoir substrate  80  to form a reservoir  100  acting as a common ink chamber of the pressure generating chambers  62 . The communicating section  63  communicates with one ends of the pressure generating chambers  62  through the ink supply channels  64 . Hence, in the present embodiment, the pressure generating chambers  62 , the communicating section  63  and the ink supply channels  64  are formed as liquid flow channels in the flow channel substrate  60 . 
     A nozzle plate  70  having nozzle apertures  71  are fixed to the open side surface of the flow channel substrate  60  with an adhesive  400 . More specifically, nozzle plates  70  are disposed corresponding to a plurality of head bodies  220 . The nozzle plate  70  has a slightly larger area than exposing opening  241  of a below-described cover head  240  and secured using the overlap with the cover head  240  with an adhesive or the like. The nozzle apertures  71  in the nozzle plate  70  are formed so as to communicate with the respective pressure generating chambers  62  at the opposite side to the ink supply channels  64 . In the present embodiment, the flow channel substrate  60  has two lines of the pressure generating chambers  62 . Accordingly, the single head body  220  has two nozzle lines  71 A in which the nozzle apertures  71  are aligned. Liquid is ejected from the liquid ejection face, which is the surface of the nozzle plate  70  in which the nozzle apertures  71  are formed. The nozzle plate  70  may be made of monocrystalline silicon, stainless steel (SUS), or a metal. 
     At the opposite side of the flow channel substrate  60  to the surface in which the openings are formed, piezoelectric elements  300  are disposed. The piezoelectric element  300  includes a metal lower electrode film, a piezoelectric layer made of lead zirconate titanate (PZT) or the like, and a metal upper electrode film that are formed in that order on the elastic film  50 . 
     A reservoir substrate  80  having reservoir sections  81 , each acting as at least part of the reservoir  100  is joined on the flow channel substrate  60  having the piezoelectric elements  300 . The reservoir section  81  passes through the thickness of the reservoir substrate  80  and extends along the widths of the pressure generating chambers  62 . Thus, the reservoir section  81  communicates with the communicating section  63  of the flow channel substrate  60  to form the reservoir  100  acting as the common ink chamber of the pressure generating chambers  62 . 
     Piezoelectric element-protecting sections  82  are formed in the reservoir substrate  80  corresponding to the piezoelectric elements  300 . The Piezoelectric element-protecting section has a space so that the piezoelectric element  300  can operate without interference. 
     In addition, driving circuits  110  are disposed on the reservoir substrate  80 . Each driving circuit  110  includes a semiconductor integrated circuit (IC) or the like and operates the piezoelectric elements  300 . The terminals of the driving circuit  110  are connected to the leads extracted from the electrodes of the piezoelectric elements  300  with bonding wires (not shown) or the like. The terminals of the driving circuit  110  are connected to the external devices with external leads  111  of a flexible printed circuit (FPC) or the like, and the driving circuit  110  receives various types of signals, such as printing signals, from the external devices through the external leads  111 . 
     A compliance substrate  140  is further disposed on the reservoir substrate  80 . The compliance substrate  140  has ink introducing holes  144  passing through the thickness of the compliance substrate  140  at the positions opposing the reservoirs  100 . Ink is introduced into the reservoir  100  through the ink introducing hole  144 . The compliance substrate  140  also has thin flexible portions  143  in the region opposing the reservoirs  100  other than the regions having the ink introducing holes  144 . The flexible portion  143  seals the reservoir  100 . The flexible portion  143  applies a compliance level to the inside of the reservoir  100 . 
     A head case  230  is secured on the compliance substrate  140 . 
     The head case  230  has an ink supply communication path  231  communicating with the ink introducing hole  144  and the liquid supply channels  36  of the supply member  30 . Thus, ink is delivered from the supply member  30  to the ink introducing hole  144  through the ink supply communication path  231 . The head case  230  has grooves  232  in the region opposing the flexible portions  143  of the compliance substrate  140  so that the flexible portions  143  can be appropriately deformed. The head case  230  also has a driving circuit holder  233  in the regions opposing to the driving circuits  110  disposed on the reservoir substrate  80 . The driving circuit holder  233  is formed so as to pass through the thickness of the head case  230 , and the external leads  111  are connected to the driving circuits  110  through the driving circuit holder  233 . 
     The head body  220  is held in the supply member  30  with the head case  230  therebetween. Thus, five head bodies  220  are relatively positioned with the liquid ejection faces covered with the box-like cover head  240 , as shown in  FIG. 2 . The cover head  240  has exposing openings  241  at which the nozzle apertures  71  are exposed, and a joint portion  242  defining the exposing openings  241  and connected to the liquid ejection faces of the head body at least at both ends of the nozzle lines  71 A of the nozzle apertures  71 . 
     The joint portion  242  includes a frame  243  disposed along the sides of the area defined by all of the liquid ejection faces of the head bodies  220 , and beams  244  extending between the head bodies  220  and separating the exposing openings  241 . The frame  243  and the beams  244  are joined to the liquid ejection faces of the head bodies  220 , that is, the surface of the nozzle plate  70 . 
     The cover head  240  also has a side wall  245  covering the periphery of the region defined by all of the liquid ejection faces. 
     The cover head  240  is joined to the head bodies  220  by bonding the joint portion  242  to the liquid ejection faces of the head bodies  220 . This structure reduces the step height between the liquid ejection faces and the cover head  240 . Consequently, ink does not remain on the liquid ejection faces after wiping of the liquid ejection faces or suctioning. Also, the beams  244  fill the gaps between the head bodies  220  to prevent the ink from penetrating between the head bodies. Consequently, the piezoelectric elements  300  and the driving circuits  110  are protected from degradation or damage caused by the ink. The gap between the liquid ejection faces of the head bodies  220  and the cover head  240  is completely filled with an adhesive, so that the print medium S is not trapped by the gap. Consequently, the deformation of the cover head  240  or paper jam can be prevented. Furthermore, the side wall  245  covers the periphery of the region defined by all of the head bodies  220  to reliably prevent the ink from flowing to the sides of the head bodies  220 . The cover head  240  has the joint portion  242  joined to the liquid ejection faces of the head bodies  220 . Consequently, the head bodies  220  are joined to the cover head  240  with the nozzle lines  71 A of the head bodies  220  precisely positioned with respect to the cover head  240 . 
     The cover head  240  can be made of, for example, stainless steel or other metal by presswork or metal forming. Such an electroconductive metal cover head  240  can be grounded. The cover head  240  and the nozzle plate  70  can be joined together by any technique without particular limitation, and may be bonded with an adhesive, such as a thermosetting epoxy adhesive or a UV-curable adhesive. 
     The ink jet recording head  11  of the present embodiment draws an ink through the liquid supply channel  36  from the ink cartridge  13 . The ink is delivered through the ink supply communication path  231  and the ink introducing hole  144  to fill the spaces from the reservoir  100  to the nozzle apertures  71 . Then, the ink jet recording head  11  applies a voltage to the piezoelectric elements  300  corresponding to the pressure generating chamber  62  according to the recording signal from the driving circuit  110 . Thus, the elastic film  50  and the piezoelectric element  300  are deformed to increase the internal pressure in the pressure generating chambers  62 , thereby ejecting the ink from the nozzle apertures  71 . 
     Second Embodiment 
       FIG. 10  is a sectional view of a supply member according to a second embodiment. The supply member  30 A of the second embodiment has the same structure as in the first embodiment, except that the outer region of the filter  33  slightly protrudes into the outer portions  34 . The same parts as in the first embodiment are designated by the same reference numerals and the descriptions will not be repeated. 
     As shown in  FIG. 10 , the filter  33 A is slightly larger than the outer diameters of the filter holding portions  37  and  42  of the supply member body  31 A and the supply needles  32 , and the outer region of the filter  33 A is held by the outer portion  34 A. The outer region from the filter holding portion  37  of the supply member body  31 A and the outer region from the filter holding portion  42  of the supply needles  32  are formed lower than the filter holding portions  37  and  42  in height, so that the resin of the outer portion  34 A can easily fill the gap. Thus, the outer portion  34 A can reliably hold the outer region of the filter  33 A. 
     Modifications 
     Although exemplary embodiments of the invention have been described, the invention is not limited to those embodiments. 
     For example, the first supply sub-member and the second supply sub-member is not limited to the structure described above. While the first supply sub-member acts as the supply member body and the second supply sub-member acts as the supply needles in the above embodiments, their functions may be reversed. While the entirety of the supply member body  31  or  31 A connected to the head body  220  defines the first supply sub-member, the supply member body  31  or  31  may be divided between the filter  33  side and the head body  220  side. The head body  220  side may be used as the first supply member to integrate with the filter  33  and the supply needles  32 . In this instance, the head body  220  side is incorporated into an integrated member of the filter and the supply needles to form the supply member  30 . 
     Although two supply needles  32  are integrated into a single member and the supply needles  32  and the supply member body  31  are further integrated with the outer portion  34 , in the above embodiments, the outer portion  34  may be simultaneously formed to seal ten liquid supply channels  36  and thus conduct integration, without particular limitation. In this instance, five two-portion filters may be used, or a filter sealing ten liquid supply channels  36  may be used.  FIG. 11  shows such a ten-portion filter including ten filter portions. The filter  33 B includes five sets of two-portion filter formed by joining the two filter portions corresponding to two liquid supply channels  36  with a joining portion  43 B. The five sets are connected to each other with joining portions  44 B. For easy introduction of the resin forming the outer portions, through holes  47 B are formed in the joining portions  43 B and  44 B. For easy formation of the connecting portion and the outer portion, the joining portions  43 B and  44 B are formed into thin straps. There is no need to say that the joining portions  43 B and  44 B may not be in a strap shape, and that the through holes  47 B may not be formed in the joining portions  43 B and  44 B. 
     The joining portions  43  of the filter  33  may not have the same shape as the connecting portion  45  acting as a resin joint. For example, in the filter  33  shown in  FIG. 4B , the width of the connecting portion  45  may be increased in the direction perpendicular to line V-V and is thus larger than the width of the joining portion  43  of the filter  33 . Consequently, the resin can easily flow around the joining portion  43  of the filter  33 . 
     While the ink cartridge  13  or liquid reservoir is removably secured to the supply member  30  in the above embodiments, an ink tank or the like acting as the liquid reservoir may be disposed in a position other than the recording head  11  and the liquid reservoir is connected to the recording head  11  with a tube or other feed pipes. In other words, the supplier is not limited to a needle type as used in the first embodiment in which the supply needles  32  are used as the suppliers. 
     While a single head body  220  is provided for a plurality of liquid supply channels  36  in the above-described embodiments, a plurality of head bodies may be provided for respective colors. In this instance, the liquid supply channels  36  may communicate with the respective head bodies. More specifically, the liquid supply channels  36  may be disposed so as to communicate with the respective nozzle lines of nozzle apertures of the head bodies. The liquid supply channels  36  may not communicate with the respective nozzle lines of course. For example, a single liquid supply channel  36  may communicate with a plurality of nozzle lines, or a single nozzle line may be divided into two sub lines communicating with respective liquid supply channels  36 . Any form can be taken as long as the liquid supply channel  36  communicates with a group of nozzle apertures. 
     While the invention has been described using an ink jet recording head  11  ejecting ink droplets in the above embodiments, the invention is intended for general liquid ejection heads. Exemplary liquid ejection heads include recording heads used in image recording apparatuses such as printers, color material ejection heads used for manufacturing color filters of liquid crystal displays, electrode material ejection heads used for forming electrodes of organic EL displays or FEDs (field emission displays), and bioorganic material ejection heads used for manufacturing bio-chips. 
     The entire disclosure of Japanese Patent Application No. 2008-056890, filed Mar. 6, 2008 is incorporated by reference herein.