Patent Publication Number: US-7722178-B2

Title: Ink-jet head

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Patent Application No. 2006-100628, filed Mar. 31, 2006, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink-jet head that ejects ink to a recording medium. 
     2. Description of Related Art 
     Some of ink-jet heads, which eject ink from nozzles to papers, include a passage unit and an ink supply block. Formed in the passage unit are individual ink passages each extending from a manifold channel through a pressure chamber to a nozzle formed on a lower face of the passage unit. The ink supply block supplies ink to a manifold channel of the passage unit. Each of the passage unit and the ink supply block has a layered structure of plates, and they are bonded to each other in a layered direction. An actuator unit is disposed on an upper face of the passage unit. A wire member that supplies a signal to the actuator unit extends through between the upper face of the passage unit and a lower face of the ink supply block, upward along a side face of the ink supply block. A volume of a pressure chamber included in an individual ink passage is selectively changed by means of the actuator unit, so that ejection energy is given to ink contained in the pressure chamber. Ink is accordingly ejected from a nozzle that communicates with this pressure chamber, and thus a desired image is printed on a paper. 
     Japanese Patent Unexamined Publication No. 2005-22183 discloses an ink-jet head in which positioning holes used in lamination of plates are formed in respective plates that constitute a passage unit and an ink supply block. These holes form through holes that extend through the passage unit and the ink supply block from their lower faces to upper faces. 
     SUMMARY OF THE INVENTION 
     In the ink-jet head disclosed in the above document, however, ink adhering to the lower face of the passage unit on which nozzles are formed may go through the through holes to the upper face of the passage unit and then further go from the lower face of the ink supply block through the through holes to the upper face of the ink supply block. As a result, ink may adhere to a wire member placed on a side face of the ink supply block, or ink may flow along the wire member and adhere to an actuator unit. This may cause electrical failure. 
     An object of the present invention is to provide an ink-jet head that can suppress occurrence of electrical failure. 
     According to an aspect of the present invention, there is provided an ink-jet head comprising a passage unit, a filter film, a piezoelectric actuator, a wire member, and an ink supply block. The passage unit is made up of a plurality of plate members laminated with each other, and includes a plurality of individual ink passages each including a pressure chamber and extending to an ink ejection port from which ink is ejected, an ink ejection face formed with a plurality of the ink ejection ports, and a support face formed with an inflow opening through which ink flows in and facing in a direction opposite to a facing direction of the ink ejection face. The filter film is attached to the support face so as to cover the inflow opening, to thereby filter ink that passes through the inflow opening. The piezoelectric actuator is attached to the support face and applies ejection energy to ink contained in the pressure chambers. The wire member is formed with a plurality of wires that are electrically connected to the piezoelectric actuator and supply an ejection signal to the piezoelectric actuator. The ink supply block is made up of a plurality of plate members laminated with each other, and includes a bond face and an ink inlet face. The bond face is formed with an outflow opening through which ink flows out, and bonded to the filter film in such a manner that the inflow opening and the outflow opening are connected through the filter film. The ink inlet face is formed with an inlet hole into which ink is injected, and faces in a direction opposite to a facing direction of the bond face. The passage unit is provided with a through hole that extends in a direction perpendicular to the ink ejection face to connect the ink ejection face and the support face. The ink supply block is provided with a through hole that extends in the direction perpendicular to the ink ejection face to connect the bond face and the ink inlet face. The filter film blocks communication between the through hole provided in the passage unit and the through hole provided in the ink supply block. 
     In the above aspect, ink cannot go from the ink ejection face to the ink inlet face through the through holes provided in the passage unit and the ink supply block. This can prevent ink from adhering to the piezoelectric actuator and the wire member. Consequently, occurrence of electrical failure can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other and further objects, features and advantages of the invention will appear more fully from the following description taken in connection with the accompanying drawings in which: 
         FIG. 1  is a perspective view showing appearance of an ink-jet head according to an embodiment of the present invention; 
         FIG. 2  is a sectional view of a reservoir unit shown in  FIG. 1 ; 
         FIG. 3A  is a top plan view of an ink introduction block shown in  FIG. 2 ; 
         FIG. 3B  is a bottom plan view of the ink introduction block shown in  FIG. 2 ; 
         FIG. 3C  is a top plan view of an uppermost plate that constitutes an ink supply block shown in  FIG. 2 ; 
         FIG. 3D  is a top plan view of an intermediate plate that constitutes the ink supply block shown in  FIG. 2 ; 
         FIG. 3E  is a bottom plan view of an lowermost plate that constitutes the ink supply block shown in  FIG. 2 ; 
         FIG. 4  is a perspective view of the ink introduction block shown in  FIG. 2 , as seen at an angle from below; 
         FIG. 5  is a perspective view of the ink introduction block shown in  FIG. 2 , as seen at an angle from above; 
         FIG. 6  is a plan view of a head main body shown in  FIG. 1 ; 
         FIG. 7  is an exploded perspective view of the head main body shown in  FIG. 6 ; 
         FIG. 8  shows a partial cross section as taken along line VIII-VIII in  FIG. 6 ; 
         FIG. 9  shows on an enlarged scale a region enclosed by an alternate long and short dash line in  FIG. 6 ; 
         FIG. 10  shows a partial cross section as taken along line X-X in  FIG. 9 ; 
         FIG. 11  shows a part of a filter film shown in  FIG. 6 , on an enlarged scale; 
         FIG. 12A  shows a cross section of an actuator unit shown in  FIG. 6 , on an enlarged scale; 
         FIG. 12B  is a plan view of an individual electrode that is disposed on a surface of the actuator unit in  FIG. 12A ; 
         FIG. 13A  is a view for explaining a step of laminating an ink supply block during a manufacturing process of the ink-jet head shown in  FIG. 1 ; 
         FIG. 13B  is a view for explaining a step of laminating a passage unit during the manufacturing process of the ink-jet head shown in  FIG. 1 ; and 
         FIG. 13C  is a view for explaining a step of laminating the passage unit and the ink supply block during the manufacturing process of the ink-jet head shown in  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, a certain preferred embodiment of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a perspective view showing appearance of an ink-jet head according to an embodiment of the present invention. As shown in  FIG. 1 , an ink-jet head  1  having a shape elongated in a main scanning direction includes, from a lower side in  FIG. 1 , a head main body  2 , a reservoir unit  3 , and a substrate  4 . The head main body  2  is opposed to a paper. The reservoir unit  3  temporarily stores ink therein, and supplies ink to a later-described passage unit  9  (see  FIG. 6 ) included in the head main body  2 . The substrate  4  is mounted with connectors  5   a  and electronic components such as capacitors  5   b . In the present description, a side of the ink-jet head  1  provided with the head main body  2  is defined as a lower side, and a side thereof provided with the substrate  4  is defined as an upper side. 
     Four actuator units  21  (see  FIG. 6 ) are fixed onto an upper face of the head main body  2 , as will be detailed later. An FPC (Flexible Printed Circuit)  6  acting as a wire member is attached onto each of the actuator units  21 . The FPC  6  extends through the head main body  2  and the reservoir unit  3 , upward along a side face of the reservoir unit  3 . Thus, the FPC  6  has one end thereof connected to the actuator unit  21 , and the other end thereof connected to a connector  5   a  of the substrate  4 . In addition, a driver IC  7  is mounted on the FPC  6  midway between the actuator unit  21  and the substrate  4 . That is, the FPC  6  is electrically connected to the substrate  4  and the driver IC  7 , so that an image signal outputted from the substrate  4  is transmitted to the driver IC  7  and a drive signal outputted from the driver IC  7  is supplied to the actuator unit  21 . 
       FIG. 2  is a sectional view of the reservoir unit  3  shown in  FIG. 1 . For the purpose of explanatory convenience,  FIG. 2  is drawn to an enlarged scale in the vertical direction.  FIGS. 3A to 3E  are exploded plan views of the reservoir unit  3  shown in  FIG. 1 . Here, both  FIGS. 3A and 3B  show an ink introduction block  11  that constitute a part of the reservoir unit  3 .  FIG. 3A  is a top plan view and  FIG. 3B  is a bottom plan view.  FIGS. 3C and 3D  are top views of plates  12  and  13 , respectively, that constitute a part of the reservoir unit  3 .  FIG. 3E  is a bottom view of a plate  14  that constitutes a part of the reservoir unit  3 .  FIG. 4  is a perspective view of the ink introduction block  11  shown in  FIG. 2 , as seen at an angle from below.  FIG. 5  is a perspective view of the ink introduction block  11  shown in  FIG. 2 , as seen at an angle from above. In order to make a structure of the ink introduction block  11  easy to understand, illustrations of a film  41 , a film  42 , and a filter  37  which will de described later are omitted from  FIGS. 3A to 5 . 
     As shown in  FIGS. 3A to 3E , the reservoir unit  3  has a layered structure laminated with an ink introduction block  11  and three plates  12  to  14 . The ink introduction block  11  is elongated in the main scanning direction. Each of the three plates  12  to  14  has a rectangular plane elongated in the main scanning direction. As shown in  FIG. 2 , the plates  12  to  14  as laminated with each other serve as an ink supply block  15 . Here, the plates  12  to  14  are metal plates made for example of a stainless steel or the like. 
     The uppermost ink introduction block  11  is made of a synthetic resin such as a polyacetal resin and a polypropylene resin for example. As shown in  FIG. 2 , an upper reservoir passage  34  is formed inside the ink introduction block  11 . The upper reservoir passage  34  makes communication between an inlet  31  and an outlet  33 . The inlet  31  is provided on an upper face  11   a  of the ink introduction block  11 , near one longitudinal end portion thereof, i.e., a left end portion in  FIG. 2 . The outlet  33  is provided on a lower face  11   b  of the ink introduction block  11 , at a longitudinal center thereof. Thus, the upper reservoir passage  34  is formed only in a portion of the ink introduction block  11  between the center and the one end with respect to an extending direction of the ink introduction block  11 . A tubular joint  30  is formed on the upper face  11   a  of the ink introduction block  11 . The tubular joint  30  surrounds the inlet  31  and protrudes upward. A connection member is connected to the joint  30 . The connection member is coupled to an end of a not-shown ink supply tube that is connected to a not-shown ink tank. Thus, ink is supplied from the ink tank through the joint  30  to the upper reservoir passage  34 . 
     As shown in  FIGS. 3A and 5 , an elliptical opening  32  is formed on the upper face  11   a  of the ink introduction block  11 . The opening  32  is elongated along a longitudinal direction of the ink introduction block  11 . The opening  32  is formed in a region of the upper face  11   a  opposed to where the upper reservoir passage  34  is formed. One longitudinal end, which means a right end in  FIGS. 2 and 3A , of the opening  32  is opposed to the outlet  33  that is formed on the lower face  11   b . As shown in  FIG. 2 , the opening  32  is sealed with the film  42 . Further, as shown in  FIGS. 3B and 4 , an opening  35  extending in the main scanning direction is formed on the lower face  11   b  of the ink introduction block  11 . The opening  35  is formed in a region stretching from a portion opposed to the inlet  31  that is formed on the upper face  11   a  to a portion opposed to a vicinity of the other end of the opening  32  that is formed on the upper face  11   a . The other end of the opening  32  is opposite to the one end thereof opposed to the outlet  33 . As shown in  FIG. 2 , the opening  35  is sealed with the film  41 . 
     Like this, due to the film  41  that seals the opening  35  and the film  42  that seals the opening  32 , the ink introduction block  11  is formed with the upper reservoir passage  32  extending from the inlet  31  that locates at the one longitudinal end portion of the ink introduction block  11  to the outlet  33  that locates at the longitudinal center of the ink introduction block  11 . As shown in  FIG. 2 , in a region of the upper reservoir passage  34  existing between a substantially central portion with respect to an extending direction of the upper reservoir  34  and a portion at which ends of the respective openings  35  and  32  are opposed to each other, a depth of the upper reservoir passage  34 , which means a length of the upper reservoir passage  34  with respect to an up-and-down direction in  FIG. 2 , is expanded upward. A filter  37  is provided in this deeper region. In this way, ink supplied from the ink tank flows through the inlet  31  into the upper reservoir passage  34 , passes through the filter  37 , and then flows out through the outlet  33 . 
     Here, the films  41  and  42  that seal the openings  35  and  32 , respectively, are made of a flexible material having an excellent gas barrier property, such as a PET (polyethylene terephthalate) film that is vapor-deposited with a silica film (SiOx film) or an aluminum film. Accordingly, air existing outside the ink-jet head  1  can hardly go through the films  41  and  42  into the upper reservoir passage  34  of the ink introduction block  11 . 
     On the lower face  11   b  of the ink supply block  11 , an annular groove  43  is formed around the outlet  33 . An O-ring  44  is fitted in the annular groove  43 , so that the outlet  33  and an inlet hole  53  are in water-tight communication with each other. As will be described later, the inlet hole  53  is formed in the plate  12 . As shown in  FIGS. 3A and 3B , four through holes  45  to  48  are formed through the ink introduction block  11  from the upper face  11   a  to the lower face  11   b . The through holes  45  to  48  are for screwing the ink introduction block  11  to the plate  12 . 
     As shown in  FIGS. 3A and 5 , two hooks  26  protruding upward are formed at each end of the ink introduction block  11  with respect to the sub scanning direction. The hooks  26  are formed on an outer peripheral side face of the ink introduction block  11 . The hooks  26  are for holding and maintaining an upper face of the substrate  4  which will be disposed on the ink introduction block  11 . 
     As shown in  FIGS. 2 and 3C , through holes  51  are formed at both longitudinal end portions, with respect to the sub scanning direction, of the uppermost plate  12  of the ink supply block  15 . The through holes  51  are used for fixing the ink-jet head  1  to a printer main body by means of screws. The plate  12  also has, at its center, a through hole that is connected to the inlet hole  53  formed on the upper face of the plate  12 . The plate  12  further has reference holes  54  at its portions a little closer to the center than the through holes  51  are. The reference holes  54  are used for positioning the plates when assembling the plates. The plate  12  further has four screw holes  56  to  59 . The four screw holes  56  to  59  correspond to the four through holes  45  to  48  of the ink introduction block  11  described above. By screwing the ink introduction block  11  and the plate  12  to each other, the outlet  33  of the ink introduction block  11  and the inlet hole  53  of the plate  12  get opposed to each other, to make communication between the upper reservoir passage  34  and the through hole of the plate  12  connected to the inlet hole  53 . 
     As shown in  FIGS. 2 and 3D , the intermediate plate  13  of the ink supply block  15  has a through hole that serves as a lower reservoir passage  86 . The lower reservoir passage  86  includes a main passage  82  and ten branch passages  83  communicating with the main passage  82 . The main passage  82  has a substantially elliptical shape elongated in a longitudinal direction of the plate  13 . A center of the main passage  82  is opposed to the inlet hole  53  of the plate  12 . A passage width of the branch passage  83  is smaller than a passage width of the main passage  82 . Any of the branch passages  83  extends from a longitudinal end of the main passage  82  to a widthwise end portion of the plate  13 . The plate  13  further has reference holes  64  each corresponding to each of the respective reference holes  54  of the plate  12 , and relief holes  61  each locating between each reference hole  64  and each longitudinal end of the plate  13 . The relief holes  61  are used in assembling the passage unit  9  and the ink supply block  15  to each other. In such an assembly step, an insertion pin  99  standing on a stationary assembly plate (see  FIG. 13C ) makes positioning as will be described later. At this time, a distal end of the insertion pin  99  locates within the relief hole  61 . 
     As shown in  FIG. 3E , the lowermost plate  14  of the ink supply block  15  has through holes that are connected to respective outflow openings  88 . The outflow openings  88 , each of which has a substantially elliptical shape in a plan view, are formed on a lower face of the plate  14  at positions opposed to ends of the respective branch passages  83 . That is, every outflow opening  88  is formed at widthwise end portion of the plate  14 . Portions of the lower face of the plate  14  surrounding the outflow openings  88  protrude, and form protrusions  89   a ,  89   b ,  89   c , and  89   d . In this embodiment, the protrusions  89   a  to  89   d  of the plate  14 , as well as the through holes connected to the outflow openings  88 , are formed by an etching process. Bond faces  90   a  to  90   d  of the protrusions  89   a  to  89   d , which are the lower face of the plate  14 , are fixed to filter films  95   a  and  95   b  that are disposed on a support face  9   a , i.e., an upper face, of the passage unit  9 , as will be described later. Consequently, a portion of the lower face of the plate  14  except the bond faces  90   a  to  90   d  is an opposing face  15   b  that is spaced apart from the support face  9   a  of the passage unit  9 . Thus, a predetermined space is formed between the opposing face  15   b  and the support face  9   a . The above-described FPC  6  extends through this space. In addition, the plate  14  has positioning holes  71  and reference holes  74  that correspond to the relief holes  61  and the reference holes  64  formed in the plate  13 , respectively. 
     By inserting insertion pins  97  (see  FIG. 13A ) into the two reference holes  54 , the two reference holes  64 , and the two reference holes  74 , which are formed in the plates  12 ,  13 , and  14 , respectively, the three plates  12  to  14  are positioned with one another. At this time, as shown in  FIG. 2 , the relief holes  61  formed in the plate  13  communicate with the positioning holes  71  formed in the plate  14 . Here, all the reference holes  54 ,  64 , and  74  formed in the respective plates  12  to  14  have the same diameter. A diameter of the relief hole  61  is larger than a diameter of the positioning hole  71  that corresponds to the relief hole  61 . The plates  12  to  14  are fixed to each other with an adhesive, thus forming the ink supply block  15 . As shown in  FIG. 2 , due to the reference holes  54 ,  64 , and  74  formed in the respective plates  12  to  14 , through holes  84  appear in the ink supply block  15 . The through holes  84  extend in a direction of lamination of the plates  12  to  14 , from the bond faces  90   a  and  90   d  which are the lower face of the ink supply block  15  to an ink inlet face  15   a  which is an upper face of the ink supply block  15 . Further, by screwing the ink introduction block  11  and the ink supply block  15  to each other, to form the reservoir unit  3 . 
     Next, a description will be given to how ink flows within the reservoir unit  3  when ink is supplied. In  FIG. 2 , black arrows indicate a flow of ink within the reservoir unit  3 . 
     Ink having flown from the not-shown ink tank into the joint  30  as described above passes through the inlet  31 , the upper reservoir passage  34 , and the outlet  33  of the ink introduction block  11 , and then flows through the inlet hole  53  of the plate  12  into the lower reservoir passage  86  of the plate  13 . That is, ink is filtered through the filter  37  provided in the upper reservoir passage  34 , and then flows into the lower reservoir passage  86 . In the main passage  82  of the lower reservoir passage  86 , ink makes stream toward both longitudinal ends of the reservoir unit  3 . At both ends of the main passage  82 , ink branches into the respective branch passages  83  and flows to the outflow openings  88  of the plate  14 . The outflow openings  88  are in communication with inflow openings  101  that are formed in the passage unit  9  as will be described later, so that ink is supplied into the passage unit  9 . 
     Like this, a series of ink passages such as the upper reservoir passage  34  and the lower reservoir passage  86  is formed in the reservoir unit  3 , and acts as an ink reservoir that temporarily stores ink therein. 
     Next, the head main body  2  will be described with reference to  FIGS. 6 to 12B .  FIG. 6  is a plan view of the head main body  2 .  FIG. 7  is an exploded perspective view of the head main body  2  shown in  FIG. 6 .  FIG. 8  shows a partial cross section as taken along line VIII-VIII in  FIG. 6 .  FIG. 9  shows on an enlarged scale a region enclosed by an alternate long and short dash line in  FIG. 6 . In  FIG. 9 , for the purpose of explanatory convenience, pressure chambers  110 , apertures  112 , and nozzles  108  are illustrated with solid lines although they locate below the actuator units  21  and therefore should actually be illustrated with broken lines.  FIG. 10  shows a partial cross section as taken along line X-X in  FIG. 9 .  FIG. 11  shows on an enlarged scale a part of a filter film shown in  FIG. 6 .  FIG. 12A  shows a cross section of the actuator unit  21  on an enlarged scale.  FIG. 12B  is a plan view of an individual electrode that is disposed on a surface of the actuator unit  21  in  FIG. 12A . 
     As shown in  FIG. 6 , the head main body  2  includes the passage unit  9 , four actuator units  21 , and filter films  95   a  and  95   b . The four actuator units  21 , and filter films  95   a  and  95   b  are fixed to the support face  9   a  of the passage unit  9 . 
     The passage unit  9  has a rectangular parallelepiped shape that is, in a plan view, substantially the same as a shape of the plate  14  of the reservoir unit  3 . As described above, a total of ten inflow openings  101  communicating with the outflow openings  88  of the ink supply block  15  are formed on the support face  9   a  of the passage unit  9 . As shown in  FIG. 6 , five of the inflow openings  101  are formed at each widthwise end portion of the passage unit  9 . To be more specific, at each widthwise end portion, two pairs of adjacent inflow openings  101  and one isolated inflow opening  101  are disposed at substantially regular intervals along a longitudinal direction of the passage unit  9 . The pairs of inflow openings  101  and the isolated inflow openings  101 , which are disposed at both widthwise end portions, are not opposed to one another with respect to a widthwise direction of the passage unit  9 . The isolated inflow opening  101  formed at one widthwise end portion, i.e., at a lower end portion in  FIG. 6 , is situated at one longitudinal end portion, i.e., at a right end portion in  FIG. 6 , and the isolated inflow opening  101  formed at the other widthwise end portion, i.e., at an upper end portion in  FIG. 6 , is situated at the other longitudinal end portion, i.e., at a let end portion in  FIG. 6 . 
     An ink ejection face  9   b  which means a lower face of the passage unit  9  provides, in its region opposed to where each actuator unit  21  is bonded, an ink ejection region in which many nozzles  108  are arranged in a matrix as shown in  FIG. 9 . The ink ejection face  9   b  is perpendicular to a direction of lamination of the reservoir unit  3  and the passage unit  9 . As shown in  FIGS. 6 and 9 , manifold channels  114  and sub manifold channels  114   a  are formed inside the passage unit  9 . The manifold channel  114  is a common ink chamber, and communicates with the inflow opening  101 . The sub manifold channel  114   a  is a branch passage of the manifold channel  114 . Connected to the sub manifold channel  114   a  are individual ink passages  132  each including a pressure chamber  110  and communicating with each nozzle  108  (see  FIG. 10 ). The individual ink passages  132  are formed in a region opposed to where each actuator unit  21  is bonded. Thus, ink flows from the inflow openings  101  into the manifold channels  114 , the sub manifold channels  114   a , and the individual ink passages  132 . 
     In the region opposed to where each actuator unit  21  is bonded, many pressure chambers  110  are arranged in a matrix. In this embodiment, as shown in  FIG. 9 , sixteen pressure chamber rows, in each of which pressure chambers  110  are arranged at regular intervals in the longitudinal direction of the passage unit  9 , which means a horizontal direction in  FIG. 9 , are disposed in parallel to each other with respect to the widthwise direction of the passage unit  9 , which means an up-and-down direction in  FIG. 9 . The number of pressure chambers  110  included in each pressure chamber row is, in conformity with an outer shape of the actuator unit  21 , which is a trapezoidal shape as will be described later, gradually reduced from a longer side to a shorter side of the actuator unit  21 . Nozzles  108  are arranged in the same manner, too. 
     As shown in  FIGS. 7 and 10 , the passage unit  9  is made up of nine plates of, from the top, a cavity plate  122 , a base plate  123 , an aperture plate  124 , a supply plate  125 , manifold plates  126 ,  127 ,  128 , a cover plate  129 , and a nozzle plate  130 . Like the plates  12  to  14  of the reservoir unit  3 , the respective plates  122  to  130  are metal plates made of a stainless steel or the like. In this embodiment, the plates  122  to  130  are made of SUS. Each of the plates  122  to  130  has a rectangular plane elongated in the main scanning direction. 
     Formed in the cavity plate  122  are many substantially rhombic through holes serving as pressure chambers  110 . Formed in the aperture plate  124  are through holes serving as apertures  112 . The apertures function as throttles, and communicate with the respective pressure chambers  110  through connection holes formed in the base plate  123 . Formed in the manifold plates  126 ,  127 , and  128  are through holes that are, when the plates are in layers, combined with each other to form manifold channels  114  and sub manifold channels  114   a . The manifold channels  114  communicate with the inflow openings  101  formed on the support face  9   a , through connection holes formed in the plates  122  to  125 . The sub manifold channels  114   a  communicate with the apertures  112  through connection holes formed in the supply plate  125 . Formed in the nozzle plate  130  are holes serving as nozzles  108 . The nozzles  108  communicate with the respective pressure chambers  110  through connection holes formed in the plates  123  to  129 . 
     The nine plates  122  to  130  are positioned, laminated, and fixed to one another so as to form, within the passage unit  9 , individual ink passages  132  each extending from an outlet of a sub manifold channel  114   a  through an aperture  112  and a pressure chamber  110  to a nozzle  108  as shown in  FIG. 10 . Positioning of the respective plates  122  to  130  is performed using lamination check holes  122   a  to  130   a  and reference holes  122   b  to  130   b  (see  FIG. 7 ), which will be detailed later. 
     As shown in  FIG. 7 , three kinds of holes, which mean the lamination check holes  122   a  to  130   a , the reference holes  122   b  to  130   b , and the positioning holes  122   c  to  130   c  are formed at both longitudinal end portions of the respective plates  122  to  130 . The three kinds of holes  122   a  to  130   a ,  122   b  to  130   b , and  122   c  to  130   c  are arranged along a longitudinal direction of the respective plates  122  to  130 . When the plates  122  to  130  are in layers, the three kinds of holes  122   a  to  130   a ,  122   b  to  130   b , and  122   c  to  130   c  respectively form three through holes  102 ,  104 , and  106  at both longitudinal end portions of the passage unit  9  (see  FIG. 6 ). The three through holes  102 ,  104 , and  106  align along the longitudinal direction of the passage unit  9 . 
     As shown in  FIG. 8 , any of the three through holes  102 ,  104 , and  106  extends through the passage unit  9 , from the upper face or the support face  9   a  to the lower face or the ink ejection face  9   b . Among the three through holes  102 ,  104 , and  106 , the middle through hole  104  is made up of the reference holes  122   b  to  130   b  that are formed in the plates  122  to  130 . The reference holes  122   b  to  130   b  are used for positioning the plates  122  to  130  in assembling the passage unit  9 . That is, all of the reference holes  122   b  to  130   b  have the same diameter, and an insertion pin  98  (see  FIG. 13B ) is inserted through the reference holes  122   b  to  130   b . The plates  122  to  130  are fixed to each other with an adhesive, to form the passage unit  9 . By positioning and laminating the plates  122  to  130  with each other using these reference holes  122   b  to  130   b , the other two through holes  102  and  106  are formed. 
     Among the three through holes  102 ,  104 , and  106 , through hole  106  closest to a longitudinal center of the passage unit  9  is made up of the lamination check holes  122   a  to  130   a  that are formed in the plates  122  to  130 . As shown in  FIG. 8 , among the lamination check holes  122   a  to  130   a , the one formed in the cavity plate  122  which is the uppermost plate in the passage unit  9  has the smallest diameter. The lower plate a lamination check hole is formed in, the larger diameter the lamination check hole has. The lamination check hole formed in the nozzle plate  130  which is the lowermost plate has the largest diameter. The lamination check holes  122   a  to  130   a  are used in laminating the plates  122  to  130 , for making a fine adjustment after rough positioning is made using the reference holes  122   b  to  130   b . As a result of the fine adjustment, the lamination check holes  122   a  to  130   a  that will form the through hole  106  are positioned substantially coaxially. 
     Among the three through holes  102 ,  104 , and  106 , the through hole  102  placed opposite to the through hole  106  across the middle through hole  104  is made up of the positioning holes  122   c  to  130   c  that are formed in the plates  122  to  130 . The through hole  102  is used for positioning the passage unit  9  and the ink supply block  15  with each other. All the positioning holes  122   c  to  130   c  have the same diameter. The through hole  102  is formed at a position corresponding to the relief hole  61  and the positioning hole  71  of the plates  13  and  14  of the ink supply block  15 , respectively. The through hole  102  has the same diameter as that of the positioning hole  71 . By inserting an insertion pin  99  (see  FIG. 13C ) through the relief hole  61 , the positioning hole  71 , and the through hole  102 , the passage unit  9  and the ink supply block  15  are positioned with each other. 
     As described above, the three through holes  102 ,  104 , and  106  are formed at the both longitudinal end portions of the passage unit  9 . Therefore, for laminating the plates  122  to  130  which will constitute the passage unit  9 , the insertion pins  98  are inserted through the two through holes  104 . For assembling the passage unit  9  and the ink supply block  15  to each other, the insertion pins  99  are inserted through the two through holes  102  and two positioning holes  71  that correspond to the two through holes  102 . 
     Filter films  95   a  and  95   b  that covers the inflow openings  101  are disposed on the support face  9   a  of the passage unit  9 . As shown in  FIG. 11 , many filter holes  96   a  are formed in a region of the filter films  95   a  and  95   b  opposed to the inflow opening  101 , to thereby provide a filter region  96  capable of filtering ink which will be supplied through the inflow openings  101  into the passage unit  9 . The filter holes  96   a  are not formed in a region not opposed to the inflow opening  101 . 
     As shown in  FIG. 6 , the filter film  95   a  covers the isolated inflow opening  101  that is situated at each longitudinal end portion of the passage unit  9 . The filter film  95   a  is disposed between a longitudinal end of the passage unit  9  and, among the four actuator units  21  fixed to the support face  9   a , the actuator unit  21  closest to this longitudinal end. The filter film  95   a  slants across a width of the passage unit  9 , and extends up to the both widthwise end portions of the passage unit  9 . A region of the filter film  95   a  other than the filter region  96  covers the through hole  106  positioned closest to the longitudinal center of the passage unit  9 . The through holes  102  and  104  are not covered with the filter film  95   a . However, even if ink adhering to the ink ejection face  9   b  comes up to the support face  9   a  through the through holes  102  and  104 , the ink cannot reach a region where the actuator units  21  exist because the filter film  95   a  is extending up to the both widthwise end portions on the support face  9   a . The filter films  95   b  extend along the longitudinal direction of the passage unit  9 , and cover four pairs of adjacent inflow openings  101 . 
     That is, the total number of the filter plates  95   a  and  95   b  is six. As illustrated with alternate long and two short dashes lines in  FIG. 6 , the filter plates  95   a  and  95   b  are disposed in regions opposed to the respective protrusions  89   a  to  89   d  that are formed on the plate  14  of the reservoir unit  3 . The filter films  95   a  and  95   b  are bonded with adhesive to the bond faces  90   a  to  90   d  of the protrusions  89   a  to  89   d . When bonded to the bond faces  90   a  and  90   d , the filter films  95   a  cover lower openings of the through holes  84  that are formed in the ink supply block  15  (see  FIG. 13C ). 
     As described above, each of the actuator units  21  is disposed in opposition to the region where pressure chambers  110  and nozzles  108  are formed. The actuator unit  21  includes actuators each opposed to each pressure chamber  110 , and has a function of giving ejection energy to ink contained within the pressure chambers  110 . 
     As shown in  FIG. 6 , in a region of the support face  9   a  between the filter films  95   a  disposed at the both longitudinal end portions, the four actuator units  21  each having a trapezoidal shape in a plan view are arranged in a zigzag pattern so as to keep out from the inflow openings  101 . More specifically, the actuator units  21  are arranged in the longitudinal direction of the passage unit  9 , with parallel opposed sides of each actuator unit  21  extending along the longitudinal direction. Oblique sides of every neighboring actuator units  21  overlap each other with respect to the widthwise direction of the passage unit  9 . 
     Since each actuator unit  21  has a trapezoidal outer shape as described above, regions causing no ink ejection appear at both outermost end portions of a set of the four actuator units  21  with respect to the main scanning direction. The regions causing no ink ejection are nonprint regions situated outside a print region in which printing on a recording medium is performed. Regions A shown in  FIG. 6  correspond to these regions. As shown in  FIG. 6 , the print region where the respective actuators are disposed is situated in a center, and the nonprint regions which are continuous with the print region serve to separate regions where the through holes  106  and the like are formed from the print region. Consequently, the actuator units  21  are not easily affected by ink intrusion. 
     As described above, the ink supply block  15  is, by means of the protrusions  89   a  to  89   d , fixed to the filter films  95   a  and  95   b  disposed on the passage unit  9 . Therefore, the opposing face  15   b  of the ink supply block  15  and the support face  9   a  of the passage unit  9  are spaced apart at an interval corresponding to a protruding height of the protrusions  89   a  to  89   d  and a thickness of the filter films  95   a  and  95   b . In this interval, the actuator units  21  are disposed. The FPC  6 , which is fixed on the actuator unit  21 , is not in contact with the opposing face  15   b  of the ink supply block  15  that is opposed to the FPC  6 . 
     The actuator unit  21  is a unimorph type actuator, and as shown in  FIG. 12A  made up of three piezoelectric sheets  141 ,  142 , and  143  each having a thickness of approximately 15 μm and made of a lead zirconate titanate (PZT)-base ceramic material with ferroelectricity. The piezoelectric sheets  141  to  143  are disposed so as to extend over many pressure chambers  110  that are formed corresponding to one ink ejection face. 
     On the uppermost piezoelectric sheet  141 , individual electrodes  135  are formed at positions opposed to the respective pressure chambers  110 . The individual electrode  135  has a thickness of approximately 1 μm. A common electrode  134  having a thickness of approximately 2 μm is interposed between the uppermost piezoelectric sheet  141  and the piezoelectric sheet  142  disposed under the uppermost piezoelectric sheet  141 . The common electrode  134  is formed over an entire surface of the sheet. Both of the individual electrodes  135  and the common electrode  134  are made of a metal material such as an Ag—Pd-base one for example. No electrode is disposed between the piezoelectric sheets  142  and  143 . 
     In a plan view, as shown in  FIG. 12B , the individual electrode  135  has a substantially rhombic shape that is substantially the same as a shape of the pressure chamber  110 . As shown in  FIGS. 12A and 12B , one acute portion of the substantially rhombic individual electrode  135  extends out to a location not opposed to the pressure chamber  110 , and a circular land  136  is provided on an end of this extending-out portion. The land  136  has a diameter of approximately 160 μm, and is electrically connected to the individual electrode  135 . The land  136  is made for example of gold including glass frits. Each land  136  is electrically bonded to a contact, i.e., a lead wire, provided on the FPC  6  (see  FIG. 1 ). 
     In a region not illustrated, the common electrode  134  is grounded. As a consequence, the common electrode  134  is, at its portions corresponding to all the pressure chambers  110 , equally kept at the ground potential. 
     Here, a mode of driving the actuator unit  21  will be described. The piezoelectric sheet  141  is polarized in its thickness direction. When an individual electrode  135  is set at a potential different from a potential of the common electrode  134 , an electric field in a polarization direction is applied to the piezoelectric sheet  141 . As a result, a portion of the piezoelectric sheet  141  to which the electric field is applied acts as an active portion which is distorted by a piezoelectric effect. That is, the piezoelectric sheet  141  extends or contracts in its thickness direction, and contracts or extends in a plane direction by a transversal piezoelectric effect. The other two piezoelectric sheets  142  and  143  form inactive layers not including a region sandwiched between an individual electrode  135  and the common electrode  134 , and therefore cannot deform by themselves. 
     When difference occurs between plane-direction distortion of a portion of the piezoelectric sheet  141  to which the electric field is applied and plane-direction distortion of the lower piezoelectric sheets  142  and  143 , the piezoelectric sheets  141  to  143  as a whole deform protrudingly toward a pressure chamber  110 , i.e. that is cause unimorph deformation. This reduces a volume of the pressure chamber  110 , so that ink is ejected from a nozzle  108 . Then, when the individual electrode  135  is set at the same potential as the potential of the common electrode  134 , the piezoelectric sheets  141  to  143  restore the original flat shape, and the volume of the pressure chamber  110  is also returned to the original one. Ink is accordingly stored into the pressure chamber  110  again. In this way, a desired image is printed on a paper. 
     Next, a process of manufacturing the ink-jet head  1  will be described with reference to  FIGS. 13A to 13C . 
     In order to manufacture the ink supply block  15 , first, three metal plates are subjected to an etching process using a patterned photoresist as a mask, to prepare the three plates  12  to  14  as shown in  FIGS. 3C to 3E . Then, as shown in  FIG. 13A , the insertion pin  97  is inserted through the reference holes  54 ,  64 , and  74  formed in the respective plates  12  to  14 , and in this condition the three plates  12  to  14  are laminated and positioned with each other. The reference holes  54 ,  64 , and  74  have the same diameter. Therefore, accurate positioning can be made by fitting therein the insertion pin  97  adapted to interfit with the reference holes  54 ,  64 , and  74 . At this time, an epoxy-base thermosetting adhesive is interposed between the respective plates  12  to  14 . Then, the three plates  12  to  14  are heated under pressure to not lower than a curing temperature of the thermosetting adhesive. As a result, the thermosetting adhesive is cured to bond the three plates  12  to  14  to each other, thus forming the ink supply block  15 . 
     In order to manufacture the head main body  2 , on the other hand, nine metal plates are subjected to an etching process using a patterned photoresist as a mask, to prepare the nine plates  122  to  130  as shown in  FIG. 7 . Then, as shown in  FIG. 13B , the insertion pin  98  is inserted through the reference holes  122   b  to  130   b  formed in the respective plates  122  to  130 , and in this condition the nine plates  122  to  130  are laminated and positioned with each other. The reference holes  122   b  to  130   b  formed in the respective plates  122  to  130  have the same diameter. Therefore, substantially accurate positioning can be made by fitting therein the insertion pin  98  adapted to interfit with the reference holes  122   b  to  130   b.    
     Further, highly accurate positioning of the plates  122  to  130  is made using the lamination check holes  122   a  to  130   a . More specifically, when laminating the cover plate  129  on the lowermost nozzle plate  130  for example, the lamination check hole  129   a  of the cover plate  129  and the lamination check hole  130   a  of the nozzle plate  130  are brought into axial alignment to thereby make highly accurate positioning of the plates  129  and  130 . At this time, an epoxy-base thermosetting adhesive is interposed between the respective plates  122  to  130 . After laminated, the plates  122  to  130  are heated under pressure to not lower than a curing temperature of the thermosetting adhesive. As a result, the nine plates  122  to  130  are bonded to each other, thus forming the passage unit  9 . Then, the actuator unit  21  prepared in a separate step and the filter films  95   a  and  95   b  are fixed to the support face  9   a  of the passage unit  9  with an adhesive, thus forming the head main body  2 . 
     Since a step of preparing the ink supply block  15  and a step of preparing the head main body  2  are performed separately, either one of them may precede the other or alternatively they may be performed simultaneously. 
     Thereafter, the FPC  6  and the actuator unit  21  are electrically connected to each other, and then the insertion pin  99  is inserted through the through hole  102  formed in the passage unit  9  and the positioning hole  71  formed in the plate  14  of the ink supply block  15 , as shown in  FIG. 13C . A distal end of the insertion pin  99  locates within the relief hole  61  formed in the plate  13  of the ink supply block  15 . At this time, the passage unit  9  and the ink supply block  15  are positioned with each other in such a manner that the inflow openings  101  of the passage unit  9  and the outflow openings  88  of the ink supply block  15  are connected through the filter films  95   a  and  95   b . Here, through hole  102  and the positioning hole  71  have the same diameter. Therefore, accurate positioning can be made by fitting therein the insertion pin  99  adapted to interfit with the through hole  102  and the positioning hole  71 . 
     At this time, an epoxy-base thermosetting adhesive is interposed between the bond faces  90   a  to  90   d  of the protrusions  89   a  to  89   d  of the ink supply block  15  and regions of the filter films  95   a  and  95   b , which are disposed on the support face  9   a  of the passage unit  9 , other than the filter regions  96 . Subsequently, the passage unit  9  and the ink supply block  15  are heated under pressure to not lower than a curing temperature of the thermosetting adhesive. As a result, the thermosetting adhesive is cured to bond the passage unit  9  and the ink supply block  15  to each other through the filter films  95   a  and  95   b.    
     In this embodiment, in a state where the passage unit  9  and the ink supply block  15  are positioned with each other, the through hole  84  formed in the ink supply block  15  is, in a plan view, at a position different from positions of the through holes  102 ,  104 , and  106  formed in the passage unit  9 , as shown in  FIG. 13C . To be more specific, the through hole  102  of the passage unit  9 , the through hole  104  of the passage unit  9 , the through hole  106  of the passage unit  9 , and the through hole  84  of the ink supply block  15  are placed in this sequence starting from the longitudinal end of the passage unit  9  and the ink supply block  15  toward a longitudinal center thereof, i.e., from left to right in  FIG. 13C . As described above, among the through holes  102 ,  104 , and  106  of the passage unit  9 , the through hole  106 , which is the one most distant from the longitudinal end of the passage unit  9 , has its upper end covered with the region of the filter film  95   a  other than the filter region  96 . Moreover, as shown in  FIG. 13C , the through hole  84  of the ink supply block  15  has its lower end covered with the region of the filter film  95   a  other than the filter region  96 . 
     Further, the ink introduction block  11 , which is separately prepared through injection molding or the like and provided with the films  41 ,  42  and the filter  37 , is fixed to the ink supply block  15  by screws, thus forming the reservoir unit  3 . In addition, the substrate  4  is engaged with the hooks  26  of the ink introduction block  11 , and thus fixed to the reservoir unit  3 . Finally, an end of the FPC  6  not connected to the actuator unit  21  is connected to the connector  5   a  of the substrate  4 . In this way, the ink-jet head  1  made up of the reservoir unit  3 , the head main body  2 , and the substrate  4  is manufactured. 
     As thus far described above, the ink-jet head  1  of this embodiment includes the passage unit  9 , the filter films  95   a , and the ink supply block  15 . The passage unit  9  has, on its upper face or the support face  9   a , the inflow openings  101  through which ink flows. The filter films  95   a  are attached to the support face  9   a  so as to cover the inflow openings  101  of the passage unit  9 . The ink supply block  15  has the inlet hole  53  into which ink is injected and the outflow openings  88  from which ink flows out. The outflow openings  88  are connected to the inflow openings  101  of the passage unit  9  through the filter films  95   a . The through holes  102 ,  104 , and  106  are formed through the passage unit  9  from its lower face or the ink ejection face  9   b  to the support face  9   a . The through holes  84  are formed through the ink supply block  15 , from its lower face or the bond faces  90   a  to  90   d  connected to the filter films  95   a , to its upper face or the ink inlet face  15   a . The filter films  95   a  inhibit communication between the through holes  84  formed in the ink supply block  15  and the through holes  102 ,  104 , and  106  formed in the passage unit  9 . Accordingly, ink cannot go from the ink ejection face  9   b  to the ink inlet face  15   a  through the through holes  102 ,  104 ,  106 , and  84 . This can prevent that ink having reached the ink inlet face  15   a  adheres to the FPC  6  which extends upward along the side face of the ink supply block  15 , or ink having reached the ink inlet face  15   a  flows along the FPC  6  and adhere to the actuator unit  21 . Consequently, electrical failure can be suppressed. 
     In the ink-jet head  1  of this embodiment, the lower openings of the through holes  84  formed in the ink supply block  15  are covered with the regions of the filter films  95   a , which are disposed on the support face  9   a  of the passage unit  9 , other than the filter regions  96  that are opposed to the inflow openings  101 . Accordingly, the filter films  95   a  block communication between the through holes  102 ,  104 , and  106  formed in the passage unit  9  and the through hole  84  formed in the ink supply block  15 . This can surely prevent ink from going from the ink ejection face  9   b  to the ink inlet face  15   a  through the through holes  102 ,  104 ,  106 , and  84 . 
     In the ink-jet head  1  of this embodiment, many filter holes  96   a  are formed only in the region of the filter film  95   a  opposed to the inflow opening  101 . That is, the filter holes  96   a  are not formed in a region of the filter film  95   a  covering the through hole  84 . Accordingly, the filter films  95   a  surely block communication between the through holes  102 ,  104 , and  106  formed in the passage unit  9  and the through hole  84  formed in the ink supply block  15 . This can more surely prevent ink from going from the ink ejection face  9   b  to the ink inlet face  15   a  through the through holes  102 ,  104 ,  106 , and  84 . 
     In the ink-jet head  1  of this embodiment, the through holes  84  formed in the ink supply block  15  are, in a plan view, at positions different from positions of the through holes  102 ,  104 , and  106  formed in the passage unit  9 . This can still more surely prevent ink from going from the ink ejection face  9   b  to the ink inlet face  15   a  through the through holes  102 ,  104 ,  106 , and  84 . 
     In the ink-jet head  1  of this embodiment, the passage unit  9  and the ink supply block  15  have elongated shapes in a plan view, and the through holes  102 ,  104 ,  106 , and  84  are formed at the both longitudinal end portions of the passage unit  9  and the ink supply block  15 . Accordingly, a relatively large actuator unit  21  can be disposed between the through holes  102 ,  104 ,  106 , and  84  which are formed in the both longitudinal end portions of the passage unit  9  and the ink supply block  15 . In addition, actuator units  21  each having a trapezoidal shape are disposed concentratedly in the vicinity of a longitudinal center, so that there are nonprint regions between the actuator units  21  and the through holes  102 ,  104 , and  106 . Therefore, ink can hardly go from the ink ejection face  9   b  into the through holes  102 ,  104 , and  106 . 
     In the ink-jet head  1  of this embodiment, the four actuator units  21  disposed on the support face  9   a  of the passage unit  9  are arranged in the longitudinal direction, in such a manner that actuator units  4  neighboring each other in the longitudinal direction have their end portions with respect to the longitudinal direction overlap each other with respect to the longitudinal direction on the support face  9   a . The filter film  95   a  is attached between a longitudinal end of the passage unit  9  and the actuator unit  21  closest to this longitudinal end. This can realize a relatively long line without increasing a size of each actuator unit  21 . 
     In the ink-jet head  1  of this embodiment, the filter film  95   a  covers the through hole  106  which is, among the through holes  102 ,  104 , and  106  formed in the passage unit  9 , the one most distant from the longitudinal end of the passage unit  9  in a plan view. That is, the through hole  106 , which is most adjacent to the actuator unit  21  and therefore most easy for ink adhering to the ink ejection face  9   b  to enter, can be covered. This can prevent ink from going into a region between the passage unit  9  and the ink supply block  15  where the actuator units  21  are disposed. 
     In the ink-jet head  1  of this embodiment, the ink supply block  15  has the opposing face  15   b  facing toward the same direction as the bond faces  90   a  to  90   d  are while being spaced apart from the support face  9   a , so that the opposing face  15   b  is opposed to the actuator units  21  with respect to a direction perpendicular to the ink ejection face  9   b . This enables the ink supply block  15  to be disposed also in a region opposed to the actuator units  21 . An amount of ink stored in the ink supply block  15  can be increased accordingly, and therefore insufficient ink supply to the passage unit  9  hardly occurs. 
     In the above-described embodiment, the lower openings of the through holes  84  formed in the ink supply block  15  and the upper openings of the through holes  106  formed in the passage unit  9  are covered with the regions of the filter films  95   a  other than the filter regions  96 . However, this is not limitative. For example, it may also be possible that either one of the through hole  84  and the through hole  106  is covered with the filter films  95   a . Here, it is preferable that, in a case where the through hole  106  alone is covered with the filter films  95   a  and the through hole  84  is not covered with the filter film  95   a , the through hole  84  locates on a side opposite to the through holes  102  and  104  with respect to the through hole  106 . Thereby, even if ink adhering to the ink ejection face  9   b  reaches the support face  9   a  through the through holes  102  and  104 , the ink hardly goes further into the through hole  84  to reach the ink inlet face  15   a . In addition, the through holes  102 ,  104 ,  106 , and  84  may not necessarily be covered with the filter film  95   a , as long as the filter film  95   a  blocks communication between the through hole  84  and the through holes  102 ,  104 , and  106 . 
     In the above-described embodiment, many filter holes  96   a  are formed only in the region of the filter film  95   a  opposed to the inflow opening  101 . However, it may not be necessary that the filter holes  96   a  are formed in an entire region of the filter film  95   a . Even in a case where the filter holes  96   a  are formed in the entire region of the filter film  95   a , by using an adhesive for fixing the filter film  95   a  to the support face  9   a  of the passage unit  9  and for fixing the filter film  95   a  to the bond face  90   a  to  90   d  of the ink supply block  15 , filter holes  96   a  formed in a region not opposed to the inflow opening  101  can be filled with the adhesive. Therefore, communication between the through holes  102 ,  104 , and  106  and the through hole  84  can be blocked by the filter film  95   a.    
     In the above-described embodiment, the through holes  84  formed in the ink supply block  15  are, in a plan view, at positions different from positions of the through holes  104  and  106  formed in the passage unit  9 . However, the through holes  84  and the through holes  104  or  106  may be at the same position in a plan view, as long as the filter films  95   a  are disposed between them. 
     In the above-described embodiment, the passage unit  9  and the ink supply block  15  have elongated shapes in a plan view, and the through holes  102 ,  104 ,  106 , and  84  are formed at the both longitudinal end portions of the passage unit  9  and the ink supply block  15 . However, this is not limitative. A shape of the passage unit  9  and a shape of the ink supply block  15  are not limited to an elongated one. 
     While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims.