Abstract:
A conductive nozzle plate is formed with a nozzle orifice. An insulative layer is formed on a first face of the nozzle plate. A head body includes a pressure chamber adapted to contain liquid therein and a pressure generating element operable to cause pressure fluctuation in the liquid. The head body is attached to a second face of the nozzle plate so as to communicate the pressure chamber with the nozzle orifice. The second face of the nozzle plate and the head body are fixed to a head case. A conductive head cover covers a part of the first face of the nozzle plate while exposing the nozzle orifice. A part of the nozzle plate and the head cover directly come into contact with each other.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a liquid ejecting head, such as an ink jet type recording head, and more particularly, to a liquid ejecting head which is provided with a nozzle forming member having a plurality of nozzle orifices formed thereon and which can eject liquid from the nozzle orifices in forms of liquid droplets. The present invention also relates to a method of manufacturing such a liquid ejecting head. 
     As a liquid ejecting head which causes a pressure change of liquid within a pressure chamber so as to eject liquid droplets from the nozzle orifices, for example, an ink jet type recording head which is used in an image recording apparatus, such as a printer or the like, a color material ejecting head which is used for manufacturing a color filter of a liquid crystal display or the like, an electrode material ejecting head which is used for forming electrodes of an organic electroluminescent (EL) display, a field emission display (FED), or the like, a biological organic material ejecting head which is used for manufacturing a bio chip (biochemical element), and the like can be used. 
     Of various types of liquid ejecting heads, for example, an ink jet type recording head (hereinafter, referred to as recording head) in an ink jet type recording apparatus (hereinafter, simply referred to as printer) is provided with a head unit (head main body) having a flow passage unit, in which a liquid flow passage from a reservoir to nozzle orifices through a pressure chamber is formed, or an actuator unit having a pressure generating element which can change a volume of the pressure chamber, a metallic nozzle plate having nozzle lines, in which a plurality of nozzle orifices are provided to be connected with the liquid flow passage, and a head case, made of resin, to which the head unit and the nozzle plate (a type of nozzle forming member) are fixed. 
     In such a recording head, flight deviation may occur in liquid droplets to be ejected according to a state around the nozzle orifice, that is, a state in which liquid, such as ink or the like, wets around the nozzle orifice. That is, if liquid, such as ink or the like, wets around the nozzle orifice, liquid droplets are pulled by a surface tension of that part at the time of eject, which causes flight deviation. In general, in order to prevent flight deviation, a liquid repellent treatment for preventing adhesion of liquid, such as ink or the like, around the nozzle orifice is performed on a liquid ejecting surface of the nozzle plate. 
     The nozzle plate in the recording head is fixed to the head case by the metallic head cover having an exposure window, through which the nozzle orifices of the nozzle plate are exposed. The head cover has a function of protecting the head unit or the nozzle plate and preventing the individual parts from being separated. In addition, the head cover, which is set to a ground potential, comes into contact with the nozzle plate to be electrically connected thereto, thereby removing static electricity generated in recording paper or the like from the nozzle plate. Accordingly, for example, an inconsistency, such as an electrostatic breakdown of a driving circuit or the like caused by static electricity to be transferred through the nozzle plate, or an inconsistency, or an erroneous operation caused by the superimposition of the static electricity on a driving signal as noise can be prevented. Such a configuration is disclosed in, for example, Japanese Patent Publication Nos. 2004-74676A and 2000-190513A. 
     Recently, however, in such a printer, there is a tendency that pigment-based ink for improving image quality or water-resistant ink for improving water resistance is used. As a solvent of such ink, instead of water, a resin-based dispersing agent is used. For this reason, a liquid repellent coating layer, which is formed on the liquid ejecting surface of the nozzle plate so as to prevent defective eject, such as flight deviation caused by ink adhesion around the nozzle orifice, needs to have high liquid repellency according to such ink. Further, in order to reduce manufacturing costs by simplifying a coating treatment process, in addition to the significant improvement of liquid repellency or quality, the liquid repellent treatment is performed on the liquid ejecting surface of the nozzle plate, for example, using a thin film deposition technology. With the liquid repellent treatment, a liquid repellent coating layer, which contains more fluorine resin is formed on the liquid ejecting surface of the nozzle plate. However, if the content ratio of fluorine resin is increased in order to enhance liquid repellency, an insulation property of the liquid ejecting surface of the nozzle plate is increased accordingly, since fluorine resin has a high insulation property. 
     On the other hand, as the water repellent film with an improved water repellent performance, the use of a glassy insulating film has been examined, as described in Japanese Patent Publication No. 2004-351923A. 
     If such a liquid repellent coating layer or an insulating film is formed on the nozzle surface of the nozzle plate, the nozzle plate and the head cover face each other through the insulating film when the head cover is simply mounted as described the above, and thus the static electricity flying from the paper to the nozzle plate or the charges of the nozzle plate cannot be released through the head cover. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a liquid ejecting head which can ensure an electrical connection between a nozzle forming member and a head cover, even when liquid repellency of a liquid ejecting surface of the nozzle forming member is improved. 
     In order to achieve the above object, according to the invention, there is provided a liquid ejection head, comprising: 
     a conductive nozzle plate, formed with a nozzle orifice; 
     an insulative layer, formed on a first face of the nozzle plate; 
     a head body, including a pressure chamber adapted to contain liquid therein and a pressure generating element operable to cause pressure fluctuation in the liquid, the head body attached to a second face of the nozzle plate so as to communicate the pressure chamber with the nozzle orifice; 
     a head case, to which the second face of the nozzle plate and the head body are fixed; and 
     a conductive head cover, covering a part of the first face of the nozzle plate while exposing the nozzle orifice, wherein a part of the nozzle plate and the head cover directly come into contact with each other. 
     A projection may be formed on the head cover so as to come in contact with the nozzle plate through the insulative layer. 
     The head cover may include a frame portion covering the part of the first face of the nozzle plate and a window portion exposing the nozzle orifice. The projection may be formed on an inner peripheral edge of the window portion. 
     The head cover may include a through hole adapted to receive a pin member for fixing the head cover to the head case. The projection may be formed on an inner peripheral edge of the through hole. 
     A projection may be formed on the first face of the nozzle plate. The insulative layer may be removed from a top face of the projection so that the top face of the projection comes in contact with the head cover. 
     A height dimension of the projection may be greater than a thickness dimension of the insulative layer. 
     A recess may be formed on the second face of the nozzle plate so as to oppose the projection. 
     A recess may be formed on the first face of the nozzle plate, and the projection may be formed around the recess. 
     The projection may be formed in the vicinity of an edge of the nozzle plate. 
     The head cover may include a fixing portion adapted to receive a screw member for fixing the head cover to the head case. The projection may be formed in the vicinity of the fixing portion. 
     The head cover may include a fixing portion adapted to receive a screw member for fixing the head cover to the head case. The projection may be formed in a region receiving a torque generated when the screw member is screwed. 
     A position of the projection may indicate a position in a mother conductive plate from which the nozzle plate is cut out. 
     The insulative layer may include a liquid repellent coating. 
     The nozzle plate may be grounded via the head cover. 
     According to the invention, there is also provided a method of manufacturing a liquid ejecting head, comprising: 
     providing a conductive nozzle plate formed with a nozzle orifice; 
     forming an insulative layer on a first face of the nozzle plate; 
     attaching a head body including a pressure chamber adapted to contain liquid therein and a pressure generating element operable to cause pressure fluctuation in the liquid, to a second face of the nozzle plate so as to communicate the pressure chamber with the nozzle orifice; 
     fixing the second face of the nozzle plate and the head body to a head case; 
     covering a part of the first face of the nozzle plate with a conductive head cover, while exposing the nozzle orifice; and 
     bringing a part of the nozzle plate and the head cover into direct contact with each other. 
     The manufacturing method may further comprise: forming a projection on the head cover; and bringing the projection into contact with the nozzle plate through the insulative layer. 
     The manufacturing method may further comprise: forming a projection on the first face of the nozzle plate; removing the insulative layer from a top face of the projection; and bringing the top face of the projection into contact with the head cover. 
     The manufacturing method may further comprise forming a recess on the second face with laser marking, thereby forming the projection. 
     The manufacturing method may further comprise forming a recess on the second face with press working, thereby forming the projection. 
     The manufacturing method may further comprise forming a recess on the first face with laser marking, thereby forming the projection. 
     The manufacturing method may further comprise: providing a mother conductive plate adapted such that a plurality of nozzle plates are cut out therefrom; and forming the projection on each of the nozzle plates such that a position of the projection indicates a position of each nozzle plate in the mother conductive plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an ink jet printer incorporating an ink jet recording head according to a first embodiment of the invention; 
         FIG. 2  is a perspective view showing a disassembled state of the ink jet recording head, viewed from an upper side thereof; 
         FIG. 3  is a perspective view showing the disassembled state of the ink jet recording head, viewed from a lower side thereof; 
         FIG. 4A  is a perspective view of a head cover in the ink jet recording head, viewed from a top side thereof; 
         FIG. 4B  is a bottom plan view of the head cover of  FIG. 4A   FIG. 5  is a plan view showing a state that the head cover is attached to a head case of the ink jet recording head; 
         FIG. 6A  is a section view taken along a line VIA-VIA in  FIG. 5 , showing a first example of a contact projection; 
         FIG. 6B  is a section view taken along a line VIB-VIB in  FIG. 5 , showing a second example of the contact projection; 
         FIGS. 7A and 7B  are schematic section views for explaining how to form the contact projection; 
         FIG. 8  is a perspective view of an ink jet recording head according to second embodiment of the invention; 
         FIG. 9  is a perspective view showing a disassembled state of the ink jet recording head of  FIG. 8 ; 
         FIG. 10  is a section view of the ink jet recording head of  FIG. 8 ; 
         FIG. 11A  is an enlarged section view showing a state that a head cover and a nozzle plate are electrically connected via contact projections in the ink jet recording head of  FIG. 8 ; 
         FIG. 11B  is an enlarged section view of the nozzle plate of  FIG. 11A ; 
         FIG. 11C  is an enlarged top plan view of the nozzle plate of  FIG. 11A ; 
         FIG. 12  is an enlarged perspective view of the nozzle plate of  FIG. 11A ; 
         FIG. 13A  is an entire plan view of the nozzle plate of  FIG. 11A ; 
         FIG. 13B  is a diagram for explaining arrangement addresses formed by the contact projections; 
         FIGS. 14 and 15  are plan views for explaining how to make the nozzle plate of  FIG. 11A ; 
         FIGS. 16A to 16D  are section views for explaining how to make the nozzle plate of  FIG. 11A ; 
         FIGS. 17A and 17B  are side views for explaining how to make the ink jet recording head. of  FIG. 8 ; 
         FIG. 18A  is a plan view showing a state that the head cover is attached to a head case of the ink jet recording head of  FIG. 8 ; 
         FIG. 18B  is a side view showing a part of the state of  FIG. 18A ; 
         FIG. 18C  is an enlarged side view of a circled part of  FIG. 18B ; 
         FIG. 19  is a schematic view showing a position relationship between the contact projections and a screwing section in the ink jet recording head of  FIG. 8 ; 
         FIG. 20  is a plan view of a nozzle plate in an ink jet recording head according to a third embodiment of the invention; 
         FIG. 21A  is an enlarged section view showing a state that a head cover and a nozzle plate are electrically connected via contact projections in an ink jet recording head according to a fourth embodiment; 
         FIG. 21B  is an enlarged section view of the nozzle plate of  FIG. 21A ; 
         FIG. 21C  is an enlarged top plan view of the nozzle plate of  FIG. 21A ; 
         FIG. 22  is an enlarged perspective view of the nozzle plate of  FIG. 21A ; and 
         FIGS. 23A to 23C  are section views for explaining how to make the nozzle plate of  FIG. 21A . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the following description, an ink jet type recording apparatus (hereinafter, simply referred to as printer), which is a representative liquid ejecting apparatus, will be exemplified. 
     As shown in  FIG. 1 , a printer  101  according to the first embodiment is an apparatus which ejects liquid ink onto the surface of a recording medium  102 , such as recording paper or the like, so as to record images or the like. The printer  101  is provided with an ink jet type recording head  103  (hereinafter, is referred to as recording head) which ejects ink, a carriage  104  on which the recording head  103  is mounted, a carriage moving mechanism  105  which moves the carriage  104  in a primary scanning direction, and a platen roller  106  which transfers the recording medium  102  in a secondary scanning direction. Here, ink, which is a type of liquid of the present invention, is stored in an ink cartridge  107 . The ink cartridge  107  can be detachably mounted with respect to the recording head  103 . 
     The carriage moving mechanism  105  is provided with a timing belt  108 , which is driven by a pulse motor  109 , such as a direct-current (DC) motor. Therefore, if the pulse motor  109  operates, the carriage  104  is guided to a guide rod  110  erected in the printer  101  so as to reciprocate in the primary scanning direction (a widthwise direction of the recording medium  102 ). 
     As shown in  FIGS. 2 and 3 , the recording head  103  comprises, in a head case  118 , a supply needle unit  112  in which a plurality of ink supply needles  111  for introducing ink within the ink cartridge  107  into the head  103  are provided, a head unit  115  having head constituting members, such as an actuator unit  113 , a flow passage unit  114 , and the like, and a nozzle plate  117  having nozzle arrays  116  in which a plurality of nozzle orifices are provided. Further, in the recording head  103 , a head cover  119  is mounted on the front end of the head case  118  so as to protect side portions of the head unit  115  or the nozzle plate  117  and to adjust the nozzle plate  117  to have a ground potential. 
     The head case  118  is a member having a base section  121  on which the supply needle unit  112  and a wiring board  120  are mounted, and a hollow box-shaped case section  122  which extends downward from the bottom portion of the base section  121  and in which the head unit  115  is mounted on an opened face thereof. The head case  118  and the ink supply needle unit  112  are formed of, for example, epoxy-based synthetic resin or the like. 
     In the base section  121  of the head case  18 , a substrate disposing section  123  in which the wiring board  120  is disposed is partitioned. The wiring board  120  is a board on which electronic components for various driving signals are mounted and connection terminals are formed to be connected to terminals at one end of a flexible cable  124  of the actuator unit  113 . In addition, the wiring board  120  includes a connector  125  to which control cables, such as flexible flat cables (FFCs) or the like, are electrically connected, though not shown. 
     The head unit  115  has the actuator unit  113  and the flow passage unit  114 , which overlap each other to be unitized. The actuator unit  113  has a laminated body of a pressure chamber plate having a pressure chamber formed to correspond to the nozzle orifice, a connection port plate having a connection port formed therein, and a vibration plate on which a piezoelectric vibrator is mounted. Further, the actuator unit  113  has the flexible cable  124 , such as a tape carrier package (TCP) or the like, a terminal at the other end of which is electrically connected to the terminal section of the piezoelectric vibrator. The piezoelectric vibrator in the actuator unit  113  is a piezoelectric vibrator in a so-called deflection vibration mode. If the piezoelectric vibrator is driven, that is, deflection-vibrated, the volume of the pressure chamber changes, such that an ink droplet (liquid droplet) is ejected from the nozzle orifice. 
     The flow passage unit  114  has a supply port plate  132  in which an ink supply port  130  and a compliance section  131  for relaxing the pressure change of a reservoir are formed, and a reservoir plate  134  in which a plurality of reservoirs  133  supplied with ink introduced from the ink cartridge are formed. The supply port plate  132  and the reservoir plate  134  are laminated and bonded to each other by a thermal welding film or the like, thereby forming an ink flow passage from the reservoir  133  to the nozzle orifice. Further, a surface of the reservoir plate  134  opposite to the bonded surface to the supply port plate  132 , that is, the bottom surface of the head unit  115  is bonded to the nozzle plate  117 . 
     As the nozzle plate  117 , a large material substrate made of, for example, stainless steel having conductivity is used. After nozzle orifices are formed in the material substrate and one surface to be a liquid ejecting surface is subjected to a liquid repellent treatment, the plurality of nozzle plates  117  are cut out from the material substrate. Therefore, a liquid repellent coating layer  135  is formed only on the liquid ejecting surface of the nozzle plate  117 . 
     Moreover, as the nozzle forming member in the present embodiment, the nozzle plate  117 , which is formed of a metal substrate, such as stainless steel, is exemplified but is not limited thereto. For example, other materials may be used, as long as at least the liquid ejecting surface is formed of a metallic base material having conductivity. 
     The liquid repellent coating layer  135  containing fluorine resin is coated on the liquid ejecting surface of the nozzle plate  117  by a thin film deposition technology. Accordingly, in addition to the improvement of liquid repellency and durability, manufacturing costs can be reduced by simplifying a liquid repellent coating process. 
     In the supply port plate  132  and the reservoir plate  134  of the flow passage unit  114 , the nozzle plate  117 , and a frame section  140  of the head cover  119 , which is mounted to overlap the nozzle plate  117 , two positioning holes  142  open at positions corresponding to positioning pins  141 . The positioning pins  141  can be correspondingly inserted into the positioning holes  142  so as to position the supply port plate  132 , the reservoir plate  134 , the nozzle plate  117 , and the frame section  140  in the head case  118 . When the positioning pins  141  are correspondingly inserted into the positioning holes  142 , the head unit  115  and the nozzle plate  117  are relatively positioned, and are fixed to the head case  118  in a state in which the nozzle plate  117  is on the lower side. Further, after the positioning pins  141  are inserted for positioning, the head cover  119  is mounted on the front end of the head case  118  so as to surround the head unit  115  and the nozzle plate  117  from the outside. 
     Next, the head cover  119  will be described. As shown in  FIGS. 4A  and  4 B, the head cover  119 , which is formed of a metallic plate, such as stainless steel or the like having conductivity, like the nozzle plate  117 , schematically has the frame section  140  in which an exposure window  143  opens at the center, and side wall sections  144  which extend from the outer circumferential edge of the frame section  140  toward the head case  118 . Further, in both the side wall sections  144  (see  FIG. 5 ) in a direction perpendicular to the nozzle arrays, ear-shaped anchoring sections  145  extend toward the sides. In the anchoring sections  145 , anchoring holes  147  open, into which anchoring pins  146  for mounting the head cover  119  on the head case  118  are inserted. In addition, the side wall sections  144  are connected to a ground line (not shown), which is connected to the printer  101 . Accordingly, the head cover  119  is adjusted to have the ground potential. 
     The exposure window  143  of the head cover  119  has a sash shape so as to expose the nozzle arrays  116 , and the size (internal size) thereof is set to be smaller than the nozzle plate  117 . Therefore, when the head cover  119  is mounted on the head case  118 , the nozzle plate  117  is exposed from the exposure window  143  while overlapping a part of the frame section  140  of the head cover  119 . 
     The frame section  140  is formed in a substantially rectangular frame shape, and has a contact projection  148  which projects from the frame section  140  toward the liquid ejecting surface of the nozzle plate  17 . The contact projection  148  is brought into contact with the metallic base material portion of the liquid ejecting surface of the nozzle plate  117  in a state in which the head cover  119  is mounted on the head case  18 . 
     The contact projection  148  in this embodiment is provided in the inner circumferential edge of the exposure window  143  of the head cover  119 . 
     As shown in  FIG. 6A , the contact projection  148  the front end of which projects toward the liquid ejecting surface from the rear surface of the frame section  140  to be brought into contact with the nozzle plate  117 , is provided along the entire inner circumferential edge of the exposure window  143 . Specifically, the sharp front end of the contact projection  148  projects by 20 μm from the rear surface of the frame section  140  toward the nozzle plate  117 . That is, L 1  in  FIG. 6A  is set to 20 μm. In addition, in a state where the head cover  119  is mounted on the head case  118 , a surface pressure applied to the anchoring section  145  when the anchoring pin  146  is mounted is applied to the frame section  140  through the side wall section  144 . And then, a force, which presses the contact projection  148  toward the liquid ejecting surface direction of the nozzle plate  117 , is also applied to the contact projection  48 . Accordingly, even when the liquid repellent coating layer  135  having a high insulation property exists on the liquid ejecting surface of the nozzle plate  117 , the contact projection  148  passes through the liquid repellent coating layer  135  so as to be brought into contact with the metallic base material portion of the nozzle plate  117 . Therefore, the connection can be reliably ensured by the contact projection  148 , and thus the nozzle plate  117  can be adjusted to have the ground potential through the head cover  119 . Accordingly, even though the liquid repellent coating layer  135  having high liquid repellency is formed on the liquid ejecting surface of the nozzle plate  117 , an inconsistency, such as an electrostatic breakdown or an erroneous operation of a driving circuit or the like due to static electricity, can be prevented. 
     Further, according to the present example, the contact projection  148  is provided over the entire inner circumferential edge of the exposure window  143  of the head cover  119 . Therefore, a clearance between the head cover  119  and the nozzle plate  117  can be blocked by the contact projection  148 . Accordingly, although misty ink droplets are slightly ejected from the nozzle orifices, the ink droplets can be prevented from intruding into the head cover  119  from the exposure window  143  of the head cover  119 . In addition, the recording medium, such as a recording paper or the like, can be prevented from being caught in the clearance between the head cover  119  and the nozzle plate  117 . 
     Moreover, the contact projection  148  may be formed by using a burr which is generated by a pressing process when the exposure window  143  is formed, If doing so, since the direction where the burr and the contact projection  148  project can be the same, the contact projection  148  can be easily formed, without needing a new process. 
     The contact projection  148  may be provided on the inner circumferential edge of the positioning hole  142   a  of the head cover  119  as shown in  FIG. 6B . 
     Specifically, the contact projection  148 , the front end of which projects toward the liquid ejecting surface of the nozzle plate  117  from the inner circumferential edge of the positioning hole  142   a  in the frame section  40 , is provided on the entire inner circumferential edge of the positioning pin  142   a . Specifically, the ring-shaped front end of the contact projection  148  projects, for example, by 20 μm from the rear surface of the frame section  140  toward the nozzle plate  117 . That is, L 2  in  FIG. 6B  is set to 20 μm. In addition, in a state in which the head cover  119  is mounted on the head case  118 , the surface pressure applied to the anchoring section  145  when the fixing pin  146  is mounted is applied to the frame section  140  through the side wall section  144 . Further, a pressure applied by caulking of the positioning pin  141  is also applied around the positioning hole  142   a . Therefore, a force is applied to the contact projection  148  toward the liquid ejecting surface of the nozzle plate  117 . Accordingly, even when the liquid repellent coating layer  135  having a high insulation property exists on the liquid ejecting surface of the nozzle plate  117 , the contact projection  148  passes through the liquid repellent coating layer  135  so as to be brought into contact with the metallic base material portion of the noble plate  117 , such that the connection can be reliably ensured. Therefore, the nozzle plate  117  can be adjusted to have the ground potential through the head cover  119 . For this reason, even though the liquid repellent coating layer  135  having high liquid repellency is formed on the liquid ejecting surface of the nozzle plate  117 , the inconsistency, such as the electrostatic breakdown or the erroneous operation of a driving circuit or the like due to the static electricity can be prevented. 
     Further, according to the present example, since the contact projection  148  is provided on the inner circumferential edge of the positioning hole  42   a  of the head cover  119 , in a state where the head cover  119  is mounted on a head case  118 , the force is applied toward the liquid ejecting surface, as described above. Accordingly, the contact projection  148  bites into the nozzle plate  117 , such that misalignment of the head cover  119  can be suppressed. Therefore, when the head cover  119  is mounted, position accuracy when the positioning pin  141  is inserted for positioning can be maintained after mounting. 
     The contact projection  148  in the present example may be formed by using a burr or bulge which is generated by a punching process when the positioning hole  142  is formed. For example, after a through hole (the positioning hole  42   a ) opens in the head cover  119 , as shown in  FIG. 7A , a punch  150   a  whose end is sharp is pressed into the through hole, such that the contact projection  148  can be formed in a shape according to the punch  150   a.    
     Further, as shown in  FIG. 7B , for example, a mold of the contact projection hole  148  is previously created in a die  149  which is used for a punching process. When the through hole (the positioning hole  142   a ) opens through the punching process, the positioning hole  142   a  and the contact projection  148  can be formed at the same time , while the bulge extruded by the punch  150   b  is formed in a shape according to the mold of the die  149 . 
     Further, the contact projection  148  may be provided in both the inner circumferential edge of the exposure window  143  of the head cover  119  and the inner circumferential edge of the positioning hole  142   a.    
     In a region on the liquid ejecting surface of the nozzle plate  117  where the contact projection  148  comes into contact with the liquid ejecting surface of the nozzle plate  117 , the contact projection  148  may come into contact with the liquid ejecting surface of the nozzle plate  117  after the liquid repellent coating layer  135  is removed in advance by the irradiation of ultraviolet rays. In this case, the contact projection  148  can be reliably brought into contact with the metallic base material portion of the liquid ejecting surface of the nozzle plate  117 , regardless of the surface pressure applied to the frame section or the pressure from the positioning pin, in a state where the head cover is mounted. 
     In this embodiment, the contact projection  148  is provided on the entire inner circumferential edge of the frame section  140 . However, the contact projection  148  may be provided on at least a portion of the inner circumferential edge of the frame section  140 . In this case, as long as the connection between the contact projection  148  and the liquid ejecting surface of the nozzle plate  117  can be ensured, the contact projection  148  can have any shape. 
     Next, a second embodiment of the invention will be described. As shown in  FIGS. 8 to 10 , an ink jet type recording head  1  is provided with a head case  16  in which a piezoelectric vibrator  14  is housed, a flow passage unit  26  which is fixed to a unit fixing face of the head case  16  by an adhesive, and a head cover  27  which covers the flow passage unit  26 . 
     The flow passage unit  26  is a laminated body of a flow passage forming substrate  11  in which a flow passage space including pressure generating chambers  19  arranged and an ink reservoir  17  for storing ink to be supplied to the individual pressure generating chambers  19 , a nozzle plate  10  which is laminated on one surface of the flow passage forming substrate  11  and which has nozzle orifices  15  to eject ink within the pressure generating chambers  19 , a vibration plate (sealing plate)  12  which is laminated on the other surface of the flow passage forming substrate  11  to seal the flow passage space including the pressure generating chambers  19 . The flow passage unit  26  eject ink pressed by the piezoelectric vibrator  14  from the nozzle orifices  15  of the nozzle plate  10 . 
     On the nozzle plate  10 , nozzle arrays  25  are formed, in each of which the plurality of nozzle orifices  15  are arranged. In this embodiment, six nozzle arrays  25  are formed to eject different types of ink The nozzle plate  10  is mainly formed of a conductive material, such as a stainless plate or the like. 
     In the flow passage forming substrate  11 , the pressure generating chambers  19  are arranged to be correspondingly connected to the nozzle orifices  15 . In addition, the common ink reservoir  17 , which is connected to the individual pressure generating chambers  19  through an ink supply passage  18  so as to store ink to be supplied to the individual pressure generating chambers  19 , is formed to be disposed along the pressure generating chambers  19 . The flow passage forming substrate  11  is formed by etching a monocrystalline silicon substrate. 
     The vibration plate  12  is formed of a resin film, such as a polyphenylene sulfide film, on which an island section  13  formed of a stainless plate or the like is laminated. 
     The flow passage unit  26  is constructed by laminating the nozzle plate  10  on one surface of the flow passage forming substrate  11  and by laminating the vibration plate  12  on the other surface thereof such that the island section  12  is disposed outside. The flow passage forming substrate  11 , the nozzle plate  10 , and the vibration plate  12  are laminated by an adhesive, are heated and held at a predetermined high temperature while being pressed in a vertical direction, and then are cooled down to a room temperature, thereby forming the flow passage unit  26 . 
     The head case  16 , which is formed by injecting thermosetting resin or thermoplastic resin, has a body section  24  which houses the piezoelectric vibrator  14 , and a flange section  28  which is formed in an opposite side to the unit fixing face of the body section  24 . 
     The body section  24  has vertical housing spaces  21 , in which the piezoelectric vibrators  14  are housed to correspond to the individual pressure generating chambers  19 . Six housing spaces  21  extending along the nozzle arrays  25  are provided to correspond to the individual nozzle arrays  25  (in  FIG. 10 , only one is shown). The piezoelectric vibrator  14  is a piezoelectric vibrator  14  in a longitudinal vibration mode, and a back end thereof is fixed to the fixing plate  20 . 
     The flange section  28  is formed on an opposite side to the unit fixing face of the body section  24  so as to extend outward from an outer circumference of the body section  24  to be stretched. 
     Further, in a state in which the vibration plate  12  of the flow passage unit  26  is bonded to the unit fixing face of the head case  16  by an adhesive, a front end face of the piezoelectric vibrator  14  is fixed to the island section  13  of the vibration plate  12 , and the fixing plate  20  is bonded and fixed to the head case  16 . 
     The head cover  27  is formed by bending a conductive metal plate, such as a stainless plate or the like. The head cover  27  is mounted on a head body  2  in which the flow passage unit  26  is fixed to the head case  16 , so as to cover the flow passage unit  26 . 
     The head cover  27  is formed in a substantially frame shape so as to cover the outer circumference of the head body  2 , and has a window  31  for exposing the nozzle orifices  15  of the nozzle formation face  30 . The head cover  27  includes a cover section  32  which covers the nozzle formation face  30  in a peripheral portion of the window  31 , side face sections  33  which are bent from the cover section  32  so as to cover the side faces of the head case  16 , and screwing sections  34  which are bent from the side face sections  33  so as to screw the head cover  27 . 
     The head cover  27  covers both end portions in a direction in which the cover section  32  is perpendicular to the nozzle arrays  25  of the nozzle formation face  30 . The side face sections cover the end portions of the flow passage unit  26  and the side faces of the head case  16 . Further, the screwing sections  34  are screwed by screws  35  with respect to the flange section  28  of the head case  16 . 
     The screwing sections  34  are formed on both sides in the direction perpendicular to the nozzle arrays  25  of the head cover  27  (a primary scanning direction in which the recording head  1  is moved by a carriage) and on one side in the direction along the nozzle arrays  25  (a secondary scanning direction perpendicular to the primary scanning direction). The screwing sections  34  screw the head cover  27  at three places. 
     The screws  35  screwed to the screwing sections  34  are configured such that the head cover  27  is mounted on the head case  16 , and the head body  2  is mounted on the carriage (not shown). The screwing sections  34  formed on both sides in the primary scanning direction are formed in the vicinities of the opposite side to one screwing section formed on one side in the secondary scanning direction, thereby supporting the head body, which is rectangular in plan view, at three points. 
     In the recording head  1  having such a configuration, a driving signal generated by a driving circuit  23  is input to the piezoelectric vibrator  14  through a flexible circuit board  22 , such that the piezoelectric vibrator  14  expands and contracts in a longitudinal direction. With the expansion and contraction of the piezoelectric vibrator  14 , the island section  13  of the vibrating body  12  vibrates, and thus a pressure within the pressure generating chamber  19  changes. And then, ink within the pressure generating chamber  19  is ejected as ink droplets from the nozzle orifices  15 . 
     The recording head  1  is mounted on the carriage which reciprocates in a widthwise direction of a recording paper, ejects ink droplets onto the recording paper while the carriage moves, and prints images or characters onto the recording paper in a dot matrix manner. 
     As shown in  FIGS. 11A through 12 , in the nozzle plate  10 , an insulating film  37  is formed on the nozzle formation face (to be opposed to a recording medium) of a conductive mother material  36  formed of stainless steel or the like. The thickness of the conductive mother material is not particularly limited, but is set to about 30 to 120 μm in accordance with ejecting characteristics. The thickness of the insulating film  37  is not particularly limited, but is set to about 0.1 to 1 μm, which is much thinner than the thickness of the conductive mother material  36 . 
     The insulating film  37  is, for example, a glassy film which exhibits water repellency. On the nozzle formation face  30  of the conductive mother material  36 , for example, a plasma-polymerized film is formed by plasma-polymerizing a silicon material. And then, a metal-alkoxide molecular film having liquid repellency is formed on the plasma-polymerized film. 
     As a raw material of the plasma-polymerized film, silicone oil, alkoxysilane, and specifically, dimethylpolysiloxane, are exemplified. As a product, TSF451 (available from GE Toshiba Silicones), SH200 (available from Dow Corning Silicones), or the like can be used. The plasma-polymerized film can be formed through the following process, for example. The plasma-polymerized film can be formed by disposing the nozzle plate  10  within a chamber, which is aspirated at a predetermined negative pressure, and by purifying argon plasma within the chamber while supplying evaporated silicone as a raw material. 
     As the metal-alkoxide molecular film, any film having water repellency and oil repellency may be used. Preferably, a metal-alkoxide mono-molecular film having a long-chain polymer group (hereinafter, referred to as long-chain RF group) including fluorine or a metalate mono-molecular film having a liquid repellent group is used. As the metal alkoxide, Ti, Li, Si, Na, K, Mg, Ca, St, Ba, Al, In, Ge, Bi, Fe, Cu, Y, Zr, Ta, or the like, can be used but silicon, titanium, aluminum, zirconium, or the like is generally used. In the present embodiment, a silicon-based product is used. Preferably, alkoxysilane having the long-chain RF group including fluorine or metalate having a liquid repellent group may be used. 
     As the long-chain RF group whose molecular weight is 1000 or more, perfluoroalkyl chain, perfluopolyether chain, or the like is exemplified. As alkoxysilane having the long-chain RF group, a silane coupling agent having the long-chain RF group or the like is exemplified. As the silane coupling agent having the long-chain RF group which is suitable as a liquid repellent film of the present invention, heptatriaconta fluoroicosyl trimethoxysilane or the like is exemplified, for example. As a product, however, OPTOOL DSX (Trademark, available from Daikin Industries, Ltd.) and KY-130 (Trademark, available from Shin-Etsu Chemical Co., Ltd.) are exemplified. Since a carbon-fluorine group (RF group) has a surface free energy smaller than an alkyl group, when the metal alkoxide contains the RF group, liquid repellency of the liquid repellent film to be formed can be improved, and characteristics, such as chemical resistance, weather resistance, and friction resistance, can be also improved. In addition, as the R F group, a group whose long-chain structure is long can further keep liquid repellency. As the metalate having a liquid repellent group, aluminate, titanate, and the like are exemplified. 
     The metal-alkoxide molecular film is formed by heating the nozzle plate  10  on which the plasma-polymerized film is formed in a range of 200 to 400° C. and by dipping into a solution in which metal alkoxide is mixed with a solvent, such as a thinner or the like, such that the concentration thereof is adjusted to, for example, 0.1 weight percent. 
     Moreover, a water repellent film is not limited to the above-described films, but various films, such as a fluorine resin film or the like, can be applied. 
     On the nozzle formation face  30  of the nozzle plate  10 , an exposure section  38  is formed, where the insulating film  37  is removed such that the conductive mother material  36  is exposed to the nozzle formation face  30  Through the exposure section  38 , the head cover  27  formed of a conductive material and the conductive mother material  36  of the nozzle plate  10  are electrically connected to each other. 
     In this embodiment, the exposure section  38  is formed as follows. That is, by forming a concave section  39  in the back face on the opposite side to the nozzle formation face  30  of the nozzle plate  10 , a contact projection  40  is formed where the conductive mother material  36  projects on the nozzle formation face  30  of the nozzle plate  10 . Further, a top region of the contact projection  40  is formed in the exposure section  38  where the insulating film  37  is removed so as to expose the conductive mother material  36 . 
     The concave section  39  and the contact projection  40  can be formed by performing laser marking on the back face (opposite to the nozzle formation face  30 ) of the nozzle plate  10 , such that the concave section  39  on the back face is formed and the contact projection  40  is formed to be swollen. Alternatively, press molding is performed in which a punch is pressed into the back face of the nozzle plate  10 , such that the concave section  39  is formed on the back face and the contact projection  40  is formed on the nozzle formation face  30  to be swollen. 
     The contact projection  40  of the conductive mother material  36  is set to have a projection height larger than the thickness of the insulating film  37 , and thus the top region of the contact projection  40  projects from the surface of the insulating film  37  toward the nozzle formation face  30 , such that the conductive mother material  36  is exposed to the nozzle formation face  30 . That is, the thickness of the insulating film  37  is set to be in a range of about 0.1 to 1 μm, while the projection height of the conductive mother material  36  of the contact projection  40  from the nozzle formation face  30  is set to, for example, about 3 to 6 μm. When the concave section  39  and the contact projection  40  are formed by laser marking, if the concave section  39  and the contact projection  40  have the same base material quality, the projection height of the contact projection  40  is changed according to the laser intensity at the time of laser marking. Therefore, control and management can be performed by regulating the laser intensity. In addition, when the contact projection  40  is formed by press molding, the projection height of the contact projection  40  can be controlled and managed by regulating a pressing degree of the punch. 
     As shown in  FIGS. 11C and 12 , a plurality of contact projections  40  are formed on the nozzle formation face  30  in the vicinity of one edge of the nozzle plate  10 . 
     As shown in  FIG. 13A , the contact projections  40  are arrayed parallel to the nozzle arrays  25  on one of both sides in the primary scanning direction. 
     As shown in  FIG. 14 , the nozzle plate  10  is formed by cutting out the plurality of nozzle plates  10  from one base material plate  41 . In this embodiment, six nozzle plates  10  are cut out from one base material plate  41  by punching with a press. Reference numeral  43  represents a punching proposed line which serves as a contour line at the time of punching. 
     Further, when the plurality of nozzle plates  10  are cut out from one base material plate  41  in such a manner, the arrangement of the nozzle plates  10  in the base material plate  41  is marked as arrangement addresses on the individual nozzle plates  10 , which can be used to analyze defects of the cut nozzle plate  10 . In this embodiment, the contact projections  40  for the electrical connection between the head cover  27  and the nozzle plate  10  also serve as the marks of arrangement addresses. 
     According to the arrangement in the base material plate  41 , No.  1 , No.  2 , No.  3 , No.  4 , No.  5 , and No.  6  (arrangement addresses) are allocated to the individual nozzle plates  10 . The arrangement addresses are marked and displayed on the individual nozzle plates  10  by forming the contact projection  40 . 
     As shown in  FIG. 13B , the arrangement addresses are marked and displayed on the individual nozzle plates  10  by the contact projections  40 , On the nozzle plate  10 , a plurality of proposed regions  42   a ,  42   b , and  42   c  for displaying the arrangement addresses are formed. In each of the proposed regions  42   a ,  42   b , and  42   c , one contact projection  40  is formed. 
     On both sides of the proposed regions  42   a ,  42   b , and  42   c , a start point mark  44   a  and an end point mark  44   b  are formed in which two contact projections  40  are provided close to each other with no gap. The region which is interposed between the start point mark  44   a  and the end point mark  44   b  is an arrangement address displaying region. In regions outside the start point mark  44   a  and the end point mark  44   b , the contact projections  40  are provided in parallel at constant pitches. 
     The number of proposed regions  42   a ,  42   b , and  42   c  are formed by at least the number of digits in a binary number when the binary number represents the number of nozzle plates  10  to be cut out from the base material plate  41 . In this embodiment, since six nozzle plates  10  are cut out from one base material plate  41  and the number of digits of ‘110’, which is a binary number of ‘6’, is ‘3’, at least three proposed regions  42   a ,  42   b , and  42   c  are provided. In this embodiment, four or more proposed regions may be provided, and only three of them may be used. 
     Among three proposed regions  42   a ,  42   b , and  42   c , according to whether or not the contact projection  40  is formed in the proposed region  42   a  close to the start point mark  44   a , ‘1’ or ‘0’ of a digit of 1 in the binary number is displayed, according to whether or not the contact projection  40  is formed in the next proposed region  42   b , ‘1’ or ‘0’ of a digit of 2 in the binary number is displayed, and according to whether or not the contact projection  40  is formed in the next proposed region  42   c , ‘1’ or ‘0’ of a digit of 4 in the binary number is displayed, such that the arrangement address is displayed. Here, in this embodiment, when the contact projection  40  is formed , ‘1’ is displayed, and, when the contact projection  40  is not formed, ‘2’ is displayed. 
     That is, in the nozzle plate  10  whose arrangement address is ‘No.  1 ’, the contact projection  40  is formed in the proposed region  42   a  of the digit of 1, not in the proposed region  42   b  of the digit of 2 and in the proposed region  42   c  of the digit of 4, thereby displaying a binary number ‘001’, that is, the arrangement address ‘ 1 ’. In the nozzle plate  10  whose arrangement address is ‘No.  2 ’, the contact projection  40  is formed in the proposed region  42   b  of the digit of 2, not in the proposed region  42   a  of the digit of 1 and in the proposed region  42   c  of the digit of 4, thereby displaying a binary number ‘010’, that is, the arrangement address ‘ 2 ’. 
     In the nozzle plate  10  whose arrangement address is ‘No.  3 ’, the contact projections  40  are formed in the proposed region  42   a  of the digit of 1 and in the proposed region  42   b  of the digit of 2, not in the proposed region  42   c  of the digit of 4, thereby displaying a binary number ‘011’, that is, the arrangement address ‘ 3 ’. In the nozzle plate  10  whose arrangement-address is ‘No.  4 ’, the contact projection  40  is formed in the proposed region  42   c  of the digit of 4, not in the proposed region  42   a  of the digit of 1 and in the proposed region  42   b  of the digit of 2, thereby displaying a binary number ‘100’, that is, the arrangement address ‘ 4 ’. 
     Similarly, in the nozzle plate  10  whose arrangement address is ‘No.  5 ’, a binary number ‘101’, that is, the arrangement address ‘ 5 ’ is displayed. In the nozzle plate  10  whose arrangement address is ‘No.  6 ’, a binary number ‘110’, that is, the arrangement address ‘ 6 ’ is displayed. 
     In this embodiment, the plurality of proposed regions  42   a ,  42   b , and  42   c  are provided along the edge of the nozzle plate  10 . Before the edge, the start point mark  44   a  is disposed on the right side, and the end point mark  44   b  is disposed on the left side. In order from the side close to the start point mark  44   a , the proposed region  42   a  of the digit of 1, the proposed region  42   b  of the digit of 2, and the proposed region  42   c  of the digit of 4 are sequentially formed. 
     As such, according to whether or not the contact projection  40  is formed in each of the plurality of proposed regions  42   a ,  42   b , and  42   c  of the arrangement address displaying region interposed between the start point mark  44   a  and the end point mark  44   b , the arrangement address of the nozzle plate  10  in the base material plate  41  is displayed. 
     The nozzle plate  10  formed in such a manner is used to form the flow passage unit  26 , thereby forming the recording head  1  (see  FIGS. 8 to 10 ). 
     In this state, the head cover  27  is electrically connected to a case of the recording apparatus through a contact plate formed on the carriage and a guide bar for guiding the reciprocation of the carriage. Accordingly, the conductive mother material  36  of the nozzle plate  10  is grounded through the head cover  27 . 
     Next, a method of manufacturing the recording head  1  of the present invention will be described. 
     First, a plate material of the conductive mother material  36  is prepared, and the nozzle orifices  15  are formed at predetermined positions inside the punching proposed line  43  by a pressing process or a laser process. 
     Next, as shown in  FIGS. 16A and 16B , the insulating film  37  is formed on the nozzle formation face  30  of the base material plate  41  in which the nozzle orifices  15  are formed. 
     Next, as shown in  FIGS. 15 and 16C , the concave section  39  is formed in the back face opposite to the nozzle formation face  30  of the base material plate  41 , on which the insulating film  37  is formed, by laser marking or press molding. The contact projection  40  is formed to be swollen on the nozzle formation face  30  to correspond to the concave section  39 . In this case, the plurality of contact projections  40  are arranged along the punching proposed line  43  in one end side parallel to the nozzle arrays  25  of on one side of both sides in the primary scanning direction in the region, which becomes the nozzle plate  10 . 
     Next, as shown in  FIG. 16D , the insulating film  37  in the top region of the contact projection  40  is removed to expose the conductive mother material  36 , such that the exposure section  38  is formed. At this time, the insulating film  37  may be grinded and removed by performing a grinding process on the nozzle formation face  30  of the nozzle plate  10 . Further, the insulating film  37  may be removed by friction between the head cover  27  and the top portion of the contact projection  40  when the head cover  27  is screwed, in particular, without using the removal process of the insulating film  37 , In a process of assembling the head cover  27 , when the exposure section  38  is formed in the contact projection  40 , the electrical connection between the exposure section  38  and the head cover  27  may be ensured. 
     In addition, as described above, the start point mark  44   a  and the end point mark  44   b  are formed in each of the nozzle plates  10  by laser marking, and simultaneously, in the region outside the start point mark  44   a  and the end point mark  44   b , the contact projections  40  are formed at constant pitches. 
     Further, as described above, the arrangement address of each nozzle plate is marked according to whether or not the contact projection  40  is formed in each of the plurality (three in this embodiment) of proposed regions  42   a ,  42   b , and  42   c  which are provided between the start point mark  44   a  and the end point mark  44   b.    
     Further, the punching proposed line  43  is cut so as to form the contour of the nozzle plate  10 , such that the nozzle plate  10  shown in  FIG. 13A  is formed. 
     Next, as shown in  FIG. 17A , the nozzle plate  10  formed in such a manner is laminated and bonded to the flow passage forming substrate  11  and the vibrating body  12  by the adhesive, thereby forming the flow passage unit  26 . At this time, since the above-described contact projection  40  is formed on the nozzle formation face  30  of the nozzle plate  10 , a cushion sheet  46  is disposed on the nozzle formation face  30  and then a pressure is applied by pressing with a press jig  47  through cushion sheet  46 , such that bonding is performed. 
     Next, as shown in  FIG. 17B , the flow passage unit  26  formed in such a manner is bonded to the head case  16  by the adhesive, thereby forming the head body  2 . At this time, the cushion sheet  46  is also disposed on the nozzle formation face  30  and a pressure is applied by pressing with the press jig  47  through the cushion sheet  46 , such that bonding is performed. 
     As the cushion seat  46 , for example, a fluorine resin sheet can be used. Since the projection height of the contact projection  40  is set in a range of about 3 to 6μm, the contact projection  40  can be sufficiently absorbed by the fluorine resin sheet, such that bonding is performed without unevenness. 
     As shown in  FIG. 18A , the head cover  27  is mounted on the head body  2  configured as described the above. That is, the head cover  27  is put on the head body  2  such that the nozzle orifices  15  of the nozzle formation face  30  are exposed from the window  31 , and the three screwing sections  34  are screwed to the flange section  28  by the screws  35 . And then, the head cover  27  is mounted on the head body  2 . At this time, when the head cover  27  is screwed so as to cover the nozzle formation face  30  and the head case  16 , the exposure section  38  of the top portion of the contact projection  40  is brought into contact with the head cover  27  and the contact projection  40  is electrically connected to the head cover  27 . 
     At this time, as shown in  FIG. 16C , the head cover  27  is mounted in a state in which the top portion of the contact projection  40  of the nozzle plate  10  is covered with the insulating film  37 . By screwing at the time of mounting, the cover section  32  of the head cover  27  scrapes against the top region of the contact projection  40 . And then, as shown in  FIG. 16D , the insulating film  37  in the scraped region is peeled off, and the conductive mother material  36  is exposed so as to form the exposure section  38 . As a result, the head cover  27  and the conductive mother material  36  of the nozzle plate  10  are electrically connected to each other. 
     By screwing the screwing sections  34 , a force, which presses the cover section  32  of the head cover  27  onto the nozzle formation face  30 , acts on the head cover  27 . Therefore, when the contact projection  40  is formed in the region close to the screwing section  34  of the head cover  27  on the nozzle formation face  30  of the nozzle plate  10 , as shown in  FIG. 19 , the electrical connection between the contact projection  40  and the head cover  27  can be reliably ensured. In this embodiment, since the screwing sections  34  are formed on both sides in the primary scanning direction of the head body  2 , the contact projections  40  are arranged in the region close to one end in the primary scanning direction of the nozzle plate  10 . 
     In the three screwing sections  34 , a clockwise torque acts when a normal right-handed screw is screwed. Therefore, on the screwing section  34   a  on the right side of  FIG. 18A  among the three screwing sections  34 , the force, which presses the cover section  32  onto the nozzle formation face  30  through the side face sections  33 , acts due to a tightening torque when the head cover  27  is screwed (see  FIGS. 18B and 18C ). Therefore, as shown in  FIG. 19 , for the sake of the reliable electrical connection, the contact projection  40  may be formed in the region where the cover section  32  is pressed onto the nozzle formation face  30  through the side face sections  33  by the tightening torque when the head cover  27  is screwed. In this case, the region is a region C which is surrounded by a dashed line in Fig,  19 . 
     With the above configurations, the conductive mother material  36  of the nozzle plate  10  and the head cover  27  are reliably connected to each other in the top region of the contact projection  40  formed on the nozzle formation face  30 . Therefore, in the nozzle plate  10  on which the insulating film  37  is formed of a water repellent film or a hydrophilic film, static electricity flying from a paper to the nozzle plate  10  or the charges of the nozzle plate  10  can be effectively released through the head cover  27 , and ejecting defects caused by dirt on the nozzle formation face  30  or a damage of an IC can be effectively prevented. 
     Further, the contact projection  40  of the conductive mother material  36  is set to have a projection height larger than the thickness of the insulating film  37 , and thus the exposure section  38  is formed at a position which projects from the surface of the insulating film  37 . Therefore, the electrical connection to the head cover  27  can be reliably ensured. 
     Further, when the concave section  39  and the contact projection  40  are formed by laser marking with respect to the back face of the nozzle plate  10 , by forming the concave section  39  on the back face of the nozzle plate  10  through laser marking, the nozzle formation face  30  may be swollen, thereby forming the contact projection  40 . Therefore, the contact projection  40  can be easily formed, manufacturing costs can be prevented from being unnecessarily increased, and position accuracy when the contact projection  40  is formed can be also improved. As a result, reliability can be ensured. 
     Further, when the concave section  39  and the contact projection  40  are formed by press molding with respect to the back face of the nozzle plate  10 , by forming the concave section  39  on the back face of the nozzle plate  10  through press molding, the nozzle formation face  30  may be swollen, thereby forming the contact projection  40 . Therefore, the contact projection  40  can be easily formed, manufacturing costs can be prevented from being unnecessarily increased, and position accuracy when the contact projection  40  is formed can be improved. As a result, reliability can be ensured. 
     Further, the contact projection  40  is formed in the region along the end side of the nozzle plate  10 , and thus the electrical connection to with the head cover  27  can be ensured in the region along the end side of the nozzle plate  10 . Therefore, an effective area of the nozzle formation face  30  to be exposed from the window  31  of the head cover  27  is not made narrower than is necessary, such that the head itself can be prevented from being enlarged. 
     Further, since the plurality of contact projections  40  are formed along the end side of the nozzle plate  10 , the electrical connection with the head cover  27  can be ensured by just one of the plurality of contact projections  40 . Therefore, a possibility of occurrence of troubles due to connection defects can be significantly reduced, such that reliability can be ensured. 
     Further, the head cover  27  includes the cover section  32  which covers the nozzle formation face  30 , the side face sections  33  which are bent from the cover section  32  so as to cover the side faces of the head case  16 , and the screwing sections  34  which are bent from the side face sections  33  so as to screw the head cover  27 . When the head cover  27  is screwed to cover the nozzle formation face  30  and the head case  16 , the contact projection  40  and the head cover  27  is electrically connected to each other. Therefore, by screwing the head cover  27 , the force is applied in a direction in which the cover section  32  of the head cover  27  is pressed onto the nozzle formation face  30 . As a result, a force is easily applied in a direction in which the cover section  32  is pressed onto the contact projection  40 , such that the connection can be reliably ensured and reliability can be improved. 
     Further, the contact projection  40  is formed in the region close to the screwing section  34  of the head cover  27  in the nozzle formation face  30  of the nozzle plate  10 . Accordingly, by forming the contact projection  40  in the region close to the screwing section  34 , the force can be easily applied in the direction in which the cover section  32  is pressed onto the contact projection  40 , such that the connection can be ensured reliably and reliability can be improved. 
     Further, the contact projection  40  is formed in the region where the cover section  32  is pressed onto the nozzle formation face  30  through the side face sections  33  by the tightening torque when the head cover  27  is screwed. Therefore, the contact projection  40  is formed in the region where the force is applied in the direction in which the cover section  32  of the head cover  27  is pressed onto the nozzle formation face  30 , by screwing the head cover  27 . As a result, the connection can be ensured reliably and reliability can be improved. 
     Further, when the plurality of nozzle plates  10  are cut out from the base material plate  41 , the contact projections  40  are formed in the proposed regions  42   a ,  42   b , and  42   c  by at least the number of digits in the binary number when the binary number represents the number of nozzle plates  10  to be cut out from the base material plate  41 . Therefore, in order to analyze defects of the plurality of the nozzle plates  10  cut out from the base material plate  41 , the contact projections  40  can be used for marking the arrangement addresses of the nozzle plates  10  in the base material plate  41 . Further, a process of forming only the contact projections  40  does not need to be provided, and thus it is very advantageous in view of process efficiency or costs. 
     Further, according to whether or not the contact projection  40  is formed in each of the proposed regions  42   a ,  42   b , and  42   c , the arrangement address of the nozzle plate  10  in the base material plate  41  is displayed. Therefore, when the contact projection  40  is used for marking the arrangement address of the nozzle plate  10  in the base material late  41 , a process of forming only the contact projection  40  does not need to be provided, and thus it is very advantageous in view of process efficiency or costs. 
     Further, the insulating film  37  is a water repellent film, and thus a glassy or ceramic film having an excellent water repellent effect can be applied. Therefore, cleanliness of the nozzle formation face after wiping can be improved, and dirt or ejecting defects on an object surface caused by dirt of the nozzle formation face can be safely reduced. 
     Further, the conductive mother material  36  of the nozzle plate  10  is grounded through the head cover  27 . Therefore, the static electricity transferred from the paper to the nozzle plate  10  or the charges of the nozzle plate  10  can be effectively released through the head cover  27 . As a result, ejecting defects or the damage of the IC caused by dirt on the nozzle formation face  30  can be effectively prevented. 
       FIG. 20  shows a third embodiment of the invention. Components similar to those in the second embodiment will be designated by the same reference numerals and repetitive explanations for those will be omitted. In this embodiment, arrays of the contact projections  40  are formed in regions close to both edges of the nozzle plate  10  in the primary scanning direction. 
     In this embodiment, the exposure section  38  is not formed in the above-described method in which the insulating film  37  is peeled off by the friction between the contact projection  40  and the head cover  27  when the head cover  27  is mounted. Alternatively, the insulating film  37  in the top region of the contact projection  40  is removed by grinding the nozzle formation face  30  of the nozzle plate  10 , thereby forming the exposure section  38 . 
     That is, the exposure section  38  may be formed by grinding the nozzle formation face of the nozzle plate  10  so as to remove the insulating film  37  in the top region of the contact projection  40  in a state of the flow passage unit  26  into which the nozzle plate  10  having the top portion of the contact projection  40  covered with the insulating film  37  is assembled or by grinding the nozzle formation face of the nozzle plate  10  so as to remove the insulating film  37  in the top region of the contact projection  40  in a state of the head body  2  in which the flow passage unit  26  is fixed to the head case  16 . 
     In this case, the contact projections  40  are arranged in the regions close to both edges in the primary scanning direction of the nozzle plate  10 , such that the posture of the flow passage unit  26  or the head body  2  during grinding is stabilized and a damage of the nozzle formation face  30  at the time of grinding is prevented. As to any other points, the same advantages as those in the second embodiment can be obtained. 
     Next, a fourth embodiment of the invention will be described. Similar components to those in the second embodiment will be designated by the same reference numerals and repetitive explanations for those will be omitted. 
     In this embodiment, an exposure section  58  shown in  FIG. 21A  is formed as follows. By performing laser marking with respect to the nozzle formation face  30  of the nozzle plate  10 , as shown in  FIGS. 21B and 21C , a concave section  59  is formed on the nozzle formation face  30  of the conductive mother material  36 , and the peripheral portion of the concave section  59  is swollen by heat or stress generated at the time of laser marking. And then, a contact projection  60 , in which the conductive mother material  36  projects on the nozzle formation face  30  of the nozzle plate  10 , is formed to be swollen, and the top region of the contact projection  60  is formed in the exposure section  58 . 
     The contact projection  60  of the conductive mother material  36  is set to have a projection height larger than the thickness of the insulating film  37 , and thus the top region of the contact projection  60  projects from the surface of the insulating film  37  on the nozzle formation face  30 , such that the conductive mother material  36  is exposed to the nozzle formation face  30 . That is, the thickness of the insulating film  37  is set in a range of bout 0.1 to 1 μm. In contrast, the projection height of the contact projection  60  from the nozzle formation face  30  of the conductive mother material  36  is set in a range of about 3 to 6 μm. If the concave section  59  and the projection section  60  have the same mother material quality, the projection height of the contact projection  60  is changed according to the laser intensity at the time of laser marking. Therefore, control and management can be performed by adjusting the laser intensity. 
     As shown in  FIGS. 21C and 22 , the contact projection  60  is formed on the nozzle formation face  30  in the vicinity of the edge of the nozzle plate  10 . The groove-shaped concave section  59  formed by laser marking opens in the end portion of the nozzle plate  10 , and the substantially U-shaped contact projection  60  is formed around the concave section  59 . 
     Specifically, as shown in  FIGS. 23A and 23B , the insulating film  37  is formed on the nozzle formation face  30  of the base material plate  41  in which the nozzle orifices  15  are formed. 
     Next, as shown in  FIG. 23C , laser marking is performed on the nozzle formation face  30  of the base material plate  41  on which the insulating film  37  is formed, thereby forming laser marks  45 . At this time, laser marking is performed so as to form the laser mark  45  in a direction perpendicular to the nozzle arrays  25 , crossing the die-cutting proposed line  34 , in one end side parallel to the nozzle arrays  25  on one side of both ends in the primary scanning direction of a region, which becomes the nozzle plate  10 . 
     The laser marks  45  are made by forming the concave section  59  in the nozzle formation face  30  of the conductive mother material  36 . The peripheral portion of the concave section  59  is swollen by heat or stress generated at the time of laser marking, and thus the contact projection  60 , in which the conductive mother material  36  projects on the nozzle formation face  30  of the nozzle plate  10 , is formed to be swollen, such that the exposure section  58  is formed in the top region of the contact projection  60 . 
     As described above, the start point mark  44   a  and the end point mark  44   b  are formed in each nozzle plate  10  by laser marking, and the laser marks  45  are formed at constant pitches outside the start point mark  44   a  and the end point mark  44   b.    
     As described above, the arrangement address of each nozzle plate is marked and displayed, according to whether or not the laser mark  45  is formed in each of the plurality (three in this embodiment) of proposed regions  42   a ,  42   b , and  42   c  which are provided between the start point mark  44   a  and the end point mark  44   b.    
     The outline of the nozzle plate  10  is formed by punching the punching proposed line  43 , and thus the nozzle plate  10  is formed. At this time, punching is performed such that the laser mark  45  is laterally cut, and thus the contact projection  60  is formed from the nozzle formation face  30  of the nozzle plate  10  up to the edge. The contact projection  60  has a substantially U shape. 
     With the above configurations, the concave section  59  is formed on the nozzle formation face  30  of the nozzle plate  10  by laser marking, and the peripheral portion of the concave section  59  is swollen, thereby forming the contact projection  60 . Therefore, the contact projection  60  can be easily formed, manufacturing costs can be prevented from being unnecessarily increased, and position accuracy when the contact projection  60  is formed can be also improved. As a result, reliability can be ensured. As to any other points, the same advantages as those in the second embodiment can be obtained. 
     In this embodiment, arrays of the contact projections  40  may formed in regions close to both edges of the nozzle plate  10  in the primary scanning direction, as in the third embodiment. 
     In the above embodiments, the insulating film  37  is a water repellent film. However, various types of insulating films  37 , such as a hydrophobic film or the like, may be applied, as long as the film has characteristics suitable for the nozzle formation face  30  of the nozzle plate  10 . 
     In the above embodiments, a plurality of nozzle plates  10  are cut out from the base material plate  41  by pressing. However, various methods, other than pressing, such as laser cutting and the like, may be used. 
     In the above embodiments, the piezoelectric vibrator  14  is used as the pressure generating element. However, a Bubble Jet (Registered Trademark) type ink jet recording head in which liquid within a pressure generating chamber is heated to generate bubbles may be used. 
     Although the present invention has been shown and described with reference to specific preferred embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. Such changes and modifications as are obvious are deemed to come within the spirit, scope and contemplation of the invention as defined in the appended claims.