Patent Publication Number: US-9403364-B2

Title: Liquid discharge head, and recording device provided with same

Description:
TECHNICAL FIELD 
     The present invention relates to a liquid discharge head and a recording device including the liquid discharge head. 
     BACKGROUND ART 
     Recently, printing apparatuses using inkjet recording method, such as inkjet printers or inkjet plotters, have been widely used in not only printers for general consumers but also industrial purposes, such as formation of electronic circuits, production of color filters for liquid crystal displays, and production of organic EL displays. 
     These inkjet type printing apparatuses include a liquid discharge head, a transport section that transports a recording medium to the liquid discharge head, and a control section that controls the liquid discharge head. Printing is carried out by driving the liquid discharge head. 
     The liquid discharge head includes a plurality of discharge holes, a plurality of pressurizing chambers respectively communicating with the discharge holes, a head body having pressurizing parts disposed correspondingly to the pressurizing chambers, a flexible wiring board electrically connected to the pressurizing parts, a first member disposed on the head body, and a second member disposed on the first member. The first member has a hole that permits insertion of the flexible wiring board (see, for example, Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Unexamined Patent Publication No. 2007-301880 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, there is a possibility that, for example, mist-state ink intrudes from the hole disposed on the first member into the head body disposed inside the liquid discharge head. The intruded ink may result in malfunction in the liquid discharge head. 
     Means for Solving the Problems 
     A liquid discharge head of the present invention includes (i) a head body which has a plurality of discharge holes, a plurality of pressurizing chambers communicating with the discharge holes, and pressurizing parts disposed correspondingly to the pressurizing chambers, (ii) a flexible wiring board electrically connected to the pressurizing parts, (iii) a first member that is disposed on the head body and has a hole, and (iv) a second member disposed on the first member. A part of the second member is disposed so as to cover the hole in a plan view. The flexible wiring board is passed through the hole and is led out from between the first member and the second member. 
     A recording device of the present invention includes the liquid discharge head, a transport section configured to transport a recording medium with respect to the liquid discharge head, and a control section configured to control the liquid discharge head. 
     Effect of the Present Invention 
     The present invention is capable of reducing the possibility that ink intrudes into the head body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration view of a printer that is a recording device including a liquid discharge head according to a first embodiment; 
         FIG. 2  is a perspective view of the liquid discharge head shown in  FIG. 1 ; 
         FIG. 3  is an exploded plan view of the liquid discharge head shown in  FIG. 1 ; 
         FIG. 4  is a cross sectional view taken along line I-I shown in  FIG. 2 ; 
         FIG. 5( a )  is a side view of the liquid discharge head shown in  FIG. 1 , and  FIG. 5( b )  is a plan view thereof; 
         FIG. 6  is a cross sectional view of the liquid discharge head shown in  FIG. 1 ; 
         FIG. 7  is a plan view of a flow channel member and a piezoelectric actuator which constitute the liquid discharge head shown in  FIG. 1 ; 
         FIG. 8  is an enlarged view of a region surrounded by a chain line in  FIG. 7 ; 
         FIG. 9  is an enlarged view of the region surrounded by the chain line in  FIG. 7 , from which some of flow channels are omitted for the sake of description; 
         FIG. 10  is a longitudinal cross sectional view taken along line II-II in  FIG. 8 ; 
         FIG. 11  is an exploded perspective view of a liquid discharge head according to a second embodiment; 
         FIG. 12  is a plan view of a second member constituting the liquid discharge head shown in  FIG. 11 ; 
         FIG. 13( a )  is an exploded perspective view of a first member of a liquid discharge head according to a third embodiment, and  FIG. 13( b )  is a cross sectional view thereof; and 
         FIG. 14( a )  is a perspective view of a liquid discharge head according to a fourth embodiment, and  FIG. 14( b )  is a cross sectional view thereof. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     First Embodiment 
       FIG. 1  is a schematic configuration view of a color inkjet printer that is a recording device including a liquid discharge head according to an embodiment of the present invention. The color inkjet printer  1  (hereinafter referred to as the printer  1 ) has four liquid discharge heads  2 . These liquid discharge heads  2  are disposed along a transport direction of a printing paper P and are secured to the printer  1 . The liquid discharge heads  2  have such a shape that is elongated in a direction from the near side to the rear side in  FIG. 1 . The elongated direction is generally referred to as one direction. 
     The printer  1  includes a paper feed unit  114 , a transport unit  120 , and a paper receiving part  116 , which are sequentially disposed along a transport path of the printing paper P. The printer  1  also includes a control section  100  to control operations in individual components of the printer  1 , such as the liquid discharge heads  2  or the paper feed unit  114 . 
     The paper feed unit  114  includes a paper storage case  115  and a paper feed roller  145 . The paper storage case  115  is capable of storing a plurality of printing papers P. The paper feed roller  145  is capable of feeding out one by one the printing paper P located uppermost among the printing papers P stackedly stored in the paper storage case  115 . 
     Two pairs of feed rollers  118   a  and  118   b , and  119   a  and  119   b  are disposed along the transport path for the printing papers P between the paper feed unit  114  and the transport unit  120 . The printing paper P fed out of the paper feed unit  114  is guided by these feed rollers  118   a  and  118   b  so as to be fed to the transport unit  120 . 
     The transport unit  120  includes a transport belt  111  and two belt rollers  106  and  107 . The transport belt  111  is entrained around the belt rollers  106  and  107 . The transport belt  111  is adjusted to such a length as to be stretched under a predetermined tension when being entrained around the two belt rollers  106  and  107 . This ensures that the transport belt  111  is stretched without looseness along two planes parallel to each other which respectively include common tangents of the two belt rollers  106  and  107 . One of these two planes which is close to the liquid discharge head  2  is a transport surface  127  along which the printing paper P is transported. 
     A transport motor  174  is connected to the belt roller  106  as shown in  FIG. 1 . The transport motor  174  is to rotate the belt roller  106  in an arrowed direction A. The belt roller  107  is rotatable interlockingly with the transport belt  111 . Accordingly, the transport belt  111  is moved along the arrowed direction A by driving the transport motor  174  so as to rotate the belt roller  106 . 
     A nip roller  138  and a nip receiving roller  139  are disposed in the vicinity of the belt roller  107  so as to hold the transport belt  111  therebetween. The nip roller  138  is energized downward by an unshown spring. The nip receiving roller  139  below the nip roller  138  receives the downwardly energized nip roller  138  with the transport belt  111  interposed therebetween. These two nip rollers are disposed rotatably so as to rotate interlockingly with the transport belt  111 . 
     The printing paper P fed from the paper feed unit  114  to the transport unit  120  is nipped between the nip roller  138  and the transport belt  111 . This ensures that the printing paper P is pressed against the transport surface  127  of the transport belt  111  so as to be adhered onto the transport surface  127 . According to the rotation of the transport belt  111 , the printing paper P is then transported in a direction in which the liquid discharge heads  2  are disposed. Alternatively, an outer peripheral surface  113  of the transport belt  111  may be subjected to processing with adhesive silicone rubber. This allows the printing paper P to be surely adhered to the transport surface  127 . 
     The four liquid discharge heads  2  are disposed closely adjacent one another along the transport direction. Each of the liquid discharge heads  2  has a head body  13  at a lower end thereof. A lower surface of the head body  13  serves as a discharge hole surface  4   a  (refer to  FIG. 10 ) having thereon a large number of discharge holes  8  (refer to  FIG. 10 ) through which the liquid is discharged. 
     Liquids (inks) having the same color are to be discharged from the discharge holes  8  disposed on the single liquid discharge head  2 . The discharge holes  8  of the liquid discharge heads  2  are equally spaced in one direction so as to ensure printing in the one direction without leaving any blank space. The colors of liquids to be discharged from the liquid discharge heads  2  are respectively, for example, magenta (M), yellow (Y), cyan (C), and black (K). These liquid discharge heads  2  are disposed between the discharge hole surface  4   a  on the lower surface of the liquid discharge head body  13  and the transport surface  127  of the transport belt  111  with a slight clearance left therebetween. 
     The printing paper P that is already transported by the transport belt  111  is then passed through a clearance between the liquid discharged head  2  and the transport belt  111 . On that occasion, liquid drops are to be discharged from the head body  13  constituting the liquid discharge head  2  toward an upper surface of the printing paper P. Consequently, a color image on the basis of image data stored by the control section  100  is formed on the upper surface of the printing paper P. 
     A peel-off plate  140  and two pairs of feed rollers  121   a  and  121   b , and  122   a  and  122   b  are disposed between the transport unit  120  and the paper receiving part  116 . The printing paper P having the color image printed thereon is then transported to the peel-off plate  140  by the transport belt  111 . On that occasion, the printing paper P is peeled off from the transport surface  127  by a right end of the peel-off plate  140 . The printing paper P is then fed to the paper receiving part  116  by the feed rollers  121   a ,  121   b ,  122   a , and  122   b . Thus, the printing papers P after being subjected to the printing are sequentially fed to the paper receiving part  116  so as to be stacked on the paper receiving part  116 . 
     A paper surface sensor  133  is disposed between the nip roller  138  and the liquid discharge head  2  located on the most upstream side in the transport direction of the printing paper P. The paper surface sensor  133  is formed of a light-emitting device and a light-receiving device, and is capable of detecting a front end position of the printing paper P on the transport path. A detection result obtained by the paper surface sensor  133  is transmitted to the control section  100 . The control section  100  is capable of controlling, for example, the liquid discharge heads  2  and the transport motor  174  or the like so as to establish synchronization between the transport of the printing paper P and the printing of the image according to the detection result transmitted from the paper surface sensor  133 . 
     The liquid discharge heads  2  are described below.  FIG. 2  is a perspective view of the liquid discharge head  2 . The liquid discharge head  2  includes the head body  13 , a reservoir flow channel member  40  disposed on the head body  13 , and a housing  90 . The housing  90  is formed of metal, and has at a part thereof a hole  90   c  that permits passage of a signal cable (not shown) through which a drive signal is transmitted. 
     As shown in  FIG. 2 , the hole  90   c  is formed at a part of an upper surface of the housing  90 , and the hole  90   c  permits passage of the signal cable which permits transmission of the drive signal and is connected to the control section  100  (refer to  FIG. 1 ). The hole  90   c  is covered with a resin lid body. The reservoir flow channel member  40  has a liquid inlet hole  41   b  at an end thereof, and liquid is to be supplied to the reservoir flow channel member  40  through the liquid inlet hole  41   b . The reservoir flow channel member  40  is an embodiment related to the first member of the present invention. The first member is described below by illustrating the reservoir flow channel member  40 . 
     As shown in  FIGS. 3 to 6 , the liquid discharge head  2  includes the head body  13  that is elongated in one direction, flexible wiring boards  92 , a branch flow channel member  60 , the reservoir flow channel member  40 , a positioning member  7 , and a substrate  94 . The branch flow channel member  60  is disposed on the head body  13 . The reservoir flow channel member  40  is disposed on the branch flow channel member  60  so as to cover the head body  13  and the branch flow channel member  60 . That is, the reservoir flow channel member  40  is disposed on the head body  13 . The positioning member  7  is disposed on the reservoir flow channel member  40 . The substrate  94  is disposed on the reservoir flow channel member  40  so as to be located in an opening  7   a  of the positioning member  7 . The reservoir flow channel member  40  has four holes  42 , and the flexible wiring boards  92  connected to the head body  13  are respectively inserted into these holes  42 . The positioning member  7  is an embodiment related to the second member of the present invention. The second member is described below by illustrating the positioning member  7 . 
     The head body  13  includes the flow channel member  4  and a piezoelectric actuator substrate  21 . The flexible wiring boards  92  are connected to the piezoelectric actuator substrate  21 . 
     The branch flow channel member  60  is disposed on the head body  13  and has the function of supplying the liquid to the head body  13 . The branch flow channel member  60  includes a branch flow channel  61  (refer to  FIG. 6 ), and a liquid inlet hole  61   b  that is one end of the branch flow channel  61  is connected to a liquid outlet hole  41   a  of a reservoir flow channel  41  of the reservoir flow channel member  40  (refer to  FIG. 6 ), and is branched halfway and connected to an opening  5   b  of a manifold in the flow channel member  4  (refer to  FIG. 7 ) through a plurality of locations. 
     The reservoir flow channel member  40  has the function of protecting the head body  13  and the branched flow channel member  60 . The reservoir flow channel member  40  has therein a reservoir flow channel  41  and has the function of supplying the liquid supplied from the exterior to the branch flow channel member  60 . 
     As shown in  FIG. 5 , the positioning member  7  is elongated in one direction and includes positioning portions  7   c  and  7   d  disposed on both ends in the one direction, a coupling portion  7   b  to connect the positioning portions  7   c  and  7   d  to each other, and an opening  7   a  formed by the positioning portions  7   c  and  7   d  and the coupling portion  7   b . The coupling portion  7   b  is disposed on the holes  42  of the reservoir flow channel member  40 . Therefore, the holes  42  of the reservoir flow channel member  40  are covered with the positioning member  7  in a plan view. 
     The positioning member  7  is used for positioning upon attachment to the printer  1 . The positioning portion  7   c  and  7   d  are respectively disposed at both ends in the one direction of the liquid discharge head  2 . The positioning portions  7   c  and  7   d  are configured to be integrated with each other by the coupling portion  7   b . Thus, the positioning portions  7   c  and  7   d  are integrated with each other. This configuration facilitates assembly because the position of the positioning portion  7   d  is settled at a predetermined position by positioning of the positioning portion  7   c , and vice versa. 
     A large distance between the positioning portions  7   c  and  7   d  is ensured by disposing the positioning portion  7   c  and  7   d  at the both ends in the one direction. Therefore, even if deformation occurs in the positioning member  7  when fixing the positioning portion  7   c , the influence exerted on the positioning portion  7   d  can be reduced to improve positioning accuracy of the attachment of the positioning member  7 . 
     The flexible wiring boards  92  are passed through the outside of the branch flow channel member  60  and are guided into the reservoir flow channel member  40 . The flexible wiring boards  92  are then led out upward through the holes  42  of the reservoir flow channel member  40 . The flexible wiring boards  92  led out of the holes  42  are in contact with the positioning member  7  and the reservoir flow channel member  40 . The flexible wiring boards  92  are pressed by the positioning member  7  disposed above and are led out upward from the opening  7   a  of the positioning member  7 . Each of the flexible wiring boards  92  has a driver IC  55  mounted on a surface thereof, and is electrically connected to a connector  95  of the substrate  94  disposed above the positioning member  7 . 
     In the liquid discharge head  2 , a part of the positioning member  7  is disposed on the holes  42  formed on the reservoir flow channel member  40 , and the flexible wiring boards  92  are respectively inserted into the holes  42  and are led out above the positioning member  7 . Consequently, the positioning member  7  is disposed so as to cover the holes  42 . Therefore, even when the mist-state ink flows in above the holes  42  when the liquid discharge heads  2  are driven to print an image, the positioning member  7  is capable of reducing the intrusion of mist-state ink into the holes  42 . This makes it possible to reduce the possibility that the mist-state ink intrudes into the head body  13 . 
     The flexible wiring boards  92  are led out above the holes  42  in a state of being contacted with the positioning member  7 . Therefore, even when the mist-state ink attaches to the flexible wiring boards  92  and the ink attached to the flexible wiring boards  92  flows downward along the flexible wiring boards  92 , the intrusion of the ink is preventable by the positioning member  7  in contact with the flexible wiring boards  92 . 
     The flexible wiring boards  92  are also in contact with the positioning member  7  and the reservoir flow channel member  40 , and are held by the positioning member  7  and the reservoir flow channel member  40 . Therefore, even when the ink attached to the flexible wiring boards  92  flows downward along the flexible wiring boards  92 , the intrusion of the ink is preventable by the positioning member  7  and the reservoir flow channel member  40  in contact with the flexible wiring boards  92 . 
     After the flexible wiring boards  92  are respectively inserted into the holes  42 , the positioning member  7  presses the flexible wiring boards  92 , and the flexible wiring boards  92  function to seal the holes  42 , thereby making it possible to improve sealability of the liquid discharge head  2 . 
     The flexible wiring boards  92  are led out upward from the inside of the opening  7   a  of the positioning member  7  and are pressed by the positioning member  7 . Therefore, the flexible wiring boards  92  are bendable toward the inside of the opening  7   a , thereby reducing the possibility that the driver IC  55  mounted on each of the flexible wiring boards  92  is peeled off upon contact with other member. 
     The flexible wiring boards  92  are inserted upward from the inside of the opening  7   a  of the positioning member  7 . Consequently, the flexible wiring boards  92  are passed through the interior of the coupling portion  7   b  of the positioning member  7 . This makes it possible to reduce the possibility that the flexible wiring boards  92  are brought into contact with other member, thereby reducing the possibility that the flexible wiring boards  92  are damaged. The present invention operates effectively, particularly in the liquid discharge heads  2  without the housing  90 . 
       FIG. 4  illustrates, by way of example, the case where the flexible wiring boards  92  are upwardly passed through the holes  42  from the inside of the opening  7   a  of the positioning member  7 . For example, the flexible wiring boards  92  may be upwardly passed through the holes  42  from the outside of the opening  7   a  of the positioning member  7 . The positioning member  7  may have a flat plate shape not having the opening  7   a . Also in these cases, a part of the positioning member  7  is located above the holes  42 , and hence the positioning member  7  covers the holes  42  and the flexible wiring boards  92 , thereby reducing the possibility of the intrusion of the ink into the liquid discharge heads  2 . 
     As shown in  FIG. 4 , the reservoir flow channel member  40  includes a side surface protection plate  43 , and the side surface protection plate  43  is in contact with a side surface along a long side of the flow channel member  4 . Consequently, a recess  63  accommodated on the piezoelectric actuator substrate  21  forms a closed space, and only openings of the holes  42  located above are communicated with the exterior. In  FIG. 6 , the side surface protection plate  43  is omitted. 
     The side surface protection plate  43  and the side surface along the long side of the flow channel member  4  may be bonded together. Alternatively, the side surface protection plate  43  may be formed of a resin so as to keep holding down with elastic deformation thereof. For example, chemical that flows and has high viscosity may be interposed between the side surface protection plate  43  and the flow channel member  4  in order to prevent the intrusion of liquid, such as ink. When the branch flow channel member  60  and the reservoir flow channel member  40  are connected to each other only at a central part in one direction, both the suppression of the intrusion of the liquid and the relaxation of stress due to a difference in coefficient of thermal expansion are attainable by keeping holding down with the elastic deformation or by interposing the chemical with the high viscosity. The side surface protection plate  43  is not necessarily required. 
     The positioning member  7  to determine the position of the head body  13 , a frame  96  having a heat insulation elastic member  97  attached thereto, and the substrate  94  having the connector  95  mounted thereon are secured to the reservoir flow channel member  40 . Although the frame  96  is not connected in the cross sectional view of  FIG. 4 , the frame  96  is secured to a portion other than the section in  FIG. 4 . 
     A drive signal transmitted from the control section  100  (refer to  FIG. 1 ) via a signal cable (not shown) to the substrate  94  is to be transmitted to the flexible wiring boards  92  via the connector  95 . The driver IC  55  mounted on each of the flexible wiring boards  92  processes the driver signal, and the processed driver signal is to drive, through the flexible wiring boards  92 , a displacement element  50  that is a liquid discharge element of the piezoelectric actuator substrate  21  so as to pressurize the liquid in the flow channel member  4 , thereby discharging liquid drops. The substrate  94  may be configured to, for example, branch a discharge signal into the driver ICs  55 , or may perform rectification of the discharge signal. Alternatively, the signal cable from the control section  100  may be directly connected to the flexible wiring boards  92  without disposing the substrate  94 . 
     The flexible wiring boards  92  are flexible belt-shaped ones and have metal wiring therein. A part of the wiring is exposed to a surface of each of the flexible wiring boards  92 , and the connector  95 , the driver IC  55 , and the piezoelectric actuator substrate  21  are electrically connected to one another by the exposed wiring. Examples of the flexible wiring boards  92  include a flexible flat cable and flexible printed circuit (FPC). 
     Each of the driver ICs  55  generates heat during the drive signal processing as described above. The driver IC  55  is pressed against the metal housing  90  by the heat insulation elastic member  97  with the flexible wiring board  92  interposed therebetween. Accordingly, the generated heat is mainly transmitted to the housing  90  and is spread rapidly over the entirety of the housing  90  so as to be released to the outside. The housing  90  is not necessarily required. 
     The connection of the positioning member  7  and the reservoir flow channel member  40  is described below with reference to  FIG. 5 . The positioning member  7  and the reservoir flow channel member  40  are screwed by a screw  70  from the side of the positioning member  7 , thereby ensuring the connection of the positioning member  7  and the reservoir flow channel member  40 . The screw  70  is an embodiment related to a connection member of the present invention. The connection member is described below by illustrating the screw  70 . 
     The liquid discharge head  2  integrated by the screw  70  is positioned by the positioning member  7  and is mounted on the printer (not shown). The positioning is carried out by bringing the positioning portions  7   c  and  7   d  into contact with two positioning pins  72   a  and  72   b  disposed vertically on the printer. 
     Firstly, the positioning portion  7   c  of the positioning member  7  is brought into contact with the positioning pin  72   a  as shown in  FIG. 5( b ) . Subsequently, the positioning portion  7   d  is brought into contact with the positioning pin  72   b  by rotating the liquid discharge head  2  around the positioning pin  72   a  in contact with the positioning portion  7   c . The positioning thus carried out ensures that the liquid discharge head  2  is mountable on the printer without being inclined in the transport direction. 
     The case of using the screw  70  as the connection member is described above by way of example only. Adhesive or a double sided tape may be used as the connection member. Alternatively, the positioning member  7  and the reservoir flow channel member  40  may be screwed by the screw  70 , or the positioning member  7  and the reservoir flow channel member  40  may be directly secured to each other. Positional accuracy between the positioning member  7  and the discharge holes  8  of the flow channel member  4  connected to the reservoir flow channel member  40  can be enhanced by screwing or directly securing the positioning member  7  and the reservoir flow channel member  40 . 
     The reservoir flow channel member  40  and the branch flow channel member  60  of the head body  13  are described below with reference to  FIG. 6 .  FIG. 6  is a cross sectional view of the flow channel member  4 , the branch flow channel member  60 , and the reservoir flow channel member  40 . 
     In the head body  13 , a branch flow channel member body  60   a  is laminated on the flow channel member  4 , and a reservoir flow channel member body  40   a  is laminated on the branch flow channel member body  60   a . The piezoelectric actuator substrate  21  including pressurizing parts is accommodated in a recess  63  of the branch flow channel member body  60   a . A branch flow channel  61  is disposed on the branch flow channel member body  60   a , and a reservoir flow channel  41  is disposed on the reservoir flow channel member body  40   a.    
     The reservoir flow channel member  40  is formed of the reservoir flow channel member body  40   a  having thereon a groove servicing as the reservoir flow channel  41 , and a plate  40   b  to cover the reservoir flow channel member body  40   a . The branch flow channel member  60  is formed of the branch flow channel member body  60   a  having thereon a groove servicing as the branch channel  61 , and a plate  60   b  to cover the branch flow channel member body  60   a.    
     In the reservoir flow channel member  40 , the plate  40   b  is disposed oppositely to the reservoir flow channel  41  so as to form the reservoir flow channel  41  on one side of the reservoir flow channel member body  40   a , and the plate  60   b  is disposed on another side of the reservoir flow channel member body  40   a . The branch flow channel member body  60   a  is disposed on the opposite side of the plate  60   b , and the branch flow channel  61  is formed by the groove disposed on the branch flow channel member body  60   a  and the plate  60   b . The flow channel member  4  having the piezoelectric actuator substrate  21  is disposed on the opposite side of the branch flow channel member body  60   a.    
     The liquid inlet hole  41   b  of the reservoir flow channel  41  is connected to an exterior liquid tank (not shown), the liquid loaded from the liquid inlet hole  41   b  of the reservoir flow channel  41  passes through the liquid outlet hole  41   a  of the reservoir flow channel  41  and enters a reservoir flow channel  61  from a liquid inlet hole  61   b  of the branch flow channel  61 . Then, the liquid flows into each of a plurality of flow channels branched halfway, passes through the liquid outlet hole  61   a  of the branch flow channel  61 , and flows from openings  5   b  of the manifolds into the manifold  5  that is a common flow channel. 
     The liquid inlet holes  41   b  of the reservoir flow channel  41  are disposed at two locations. One of the liquid inlet holes  41   b  is basically only used for releasing air or liquid when liquid is firstly loaded, and the liquid is supplied from either one and the other is closed during printing. This ensures that the liquid in the reservoir flow channel  41  flows mainly from the liquid inlet hole  41   b  of the reservoir flow channel  41  that permits loading of the liquid to the liquid outlet hole  41   a  of the centrally located reservoir flow channel  41 , and the liquid seldom flows on the closed liquid inlet hole side. When a temperature of the liquid loaded from the outside is different from a temperature of the head body  13 , the temperature of the head body  13  is changed, and the temperature on the liquid inlet side is changed greatly due to imbalance of the liquid motion as described above. 
     A part of an inner wall of the reservoir flow channel  41  is a damper  47  formed of an elastically deformable material. A surface of the damper  47  opposite to the reservoir flow channel  41  is deformable in a facing direction. Therefore, a volume of the reservoir flow channel  41  is changeable by elastic deformation of the damper  47 . This makes it possible to stably supply the liquid when, for example, the amount of discharge of the liquid is rapidly increased. The damper  47  is configured to face a space formed in the reservoir flow channel member body  40   a  in order to accommodate a heater  65  therein. This improves space efficiency and downsizes the liquid discharge head  2 . Additionally, heat conduction can be further suppressed by loading the liquid from a side on which the damper  47  is disposed. 
     A filter  45  is preferably disposed in the reservoir flow channel  41  in order to prevent foreign matter contained in the liquid from entering the branch flow channel member  4 , thereby suppressing non-discharge caused by clogging of the foreign matter. 
     The reservoir flow channel member body  40   a  and the branch flow channel member body  60   a  are formed of a metal or alloy member. Alternatively, both are producible with a resin. Even when the reservoir flow channel  41  and the branch flow channel  61  have a complicated shape, an inexpensive production thereof is attainable by producing both with the resin. The plates  40   b  and  60   a  are also formed of a metal or alloy member or a resin. 
     The flow channel member  4  constituting the liquid discharge head  2  is described below.  FIG. 7  is a plan view showing the flow channel member  4  and the piezoelectric actuator substrate  21  of the head body  13 .  FIG. 8  is an enlarged plan view of a region surrounded by a chain line in  FIG. 7 , and shows a part of the head body  13 .  FIG. 9  is an enlarged perspective view at the same position as that of  FIG. 8 , from which some of the flow channels are omitted to make the positions of the discharge holes  8  more understandable. In  FIGS. 8 and 9 , for the purpose of further clarification of the drawing, the pressurizing chambers  10  (pressurizing chamber groups  9 ), the apertures  12 , and the discharge holes  8 , which are located below the piezoelectric actuator substrate  21  and therefore should be drawn by a dashed line, are drawn by a solid line.  FIG. 10  is a longitudinal cross sectional view taken along line II-II in  FIG. 8 . 
     The head body  13  includes the flow channel member  4  having a flat plate shape, and the piezoelectric actuator substrate  21  that is disposed on the flow channel member  4  and includes the pressurizing parts. The piezoelectric actuator substrate  21  has a trapezoidal shape and is disposed on an upper surface of the flow channel member  4  so that a pair of parallel opposite sides of a trapezoid is parallel to one direction of the flow channel member  4 . 
     The flow channel member  4  has thereon four piezoelectric actuator substrates  21 , two along each of two virtual straight lines parallel to the one direction of the flow channel member  4 . These four piezoelectric actuator substrates  21  are generally arranged in zigzag form on the flow channel member  4 . Oblique sides of the piezoelectric actuator substrates  21  adjacent to each other on the flow channel member  4  are partially overlapped with each other in a transverse direction of the flow channel member  4 . 
     The manifold  5  is formed in the flow channel member  4 . The manifold  5  has an elongated shape extending along the one direction of the flow channel member  4 , and the opening  5   b  of the manifold  5  is formed on an upper surface of the flow channel member  4 . There are ten openings  5   b , five along each of two straight lines (virtual lines) parallel to the one direction of the flow channel member  4 . These openings  5   b  are disposed at positions other than a region in which the four piezoelectric actuator substrates  21  are disposed. The liquid is to be supplied from an unshown liquid tank to the manifold  5  through the opening  5   b.    
     The manifold  5  formed in the flow channel member  4  is branched into a plurality of pieces. The manifold  5  located at branched portions is generally referred to as a sub manifold  5   a , and the manifold  5  extending from the opening  5   b  to the sub manifold  5   a  is generally referred to as a liquid supply channel  5   c . The liquid supply channel  5   c  connected to the opening  5   b  extends along the oblique side of the piezoelectric actuator substrate  21  and is disposed so as to intersect the one direction of the flow channel member  4 . In a region lying between the two piezoelectric actuator substrates  21 , the single manifold  5  is shared by the piezoelectric actuator substrates  21  adjacent to each other, and the sub manifolds  5   a  are branched on both sides of the manifold  5 . These sub manifolds  5   a  are adjacent to each other in regions of the interior of the flow channel member  4  which are respectively opposed to the piezoelectric actuator substrates  21 , and extend in one direction of the head body  13 . That is, both ends of the sub manifold  5   a  are connected to the liquid supply channel  5   c.    
     The flow channel member  4  includes four pressurizing chamber groups  9 , each having a plurality of pressurizing chambers  10  disposed in matrix form (namely, two-dimensionally and regularly). The pressurizing chambers  10  are hollow regions having an approximately rhombus planar shape whose corners are rounded. The pressurizing chambers  10  are formed so as to open into the upper surface of the flow channel member  4 . These pressurizing chambers  10  are arranged approximately over the entire surface of a region of the upper surface of the flow channel member  4  which is opposed to the piezoelectric actuator substrates  21 . Therefore, the pressurizing chamber groups  9  each being formed by these pressurizing chambers  10  occupy a region having approximately the same size and shape as the piezoelectric actuator substrates  21 . Openings of the pressurizing chambers  10  are closed by adhesion of the piezoelectric actuator substrates  21  to the upper surface of the flow channel member  4 . 
     In the present embodiment, as shown in  FIG. 9 , the manifold  5  is branched into four columns E 1  to E 4  of the sub manifolds  5   a  arranged parallel to one another in the transverse direction of the flow channel member  4 . The pressurizing chambers  10  respectively connected to the sub manifolds  5   a  constitute a column of the pressurizing chambers  10  equally spaced in the one direction of the flow channel member  4 , and four columns thereof are arranged parallel to one another in the transverse direction. These four columns in which the pressurizing chambers  10  connected to the sub manifolds  5   a  are arranged two on each side of the sub manifold  5   a.    
     In entirety, the pressurizing chambers  10  respectively connected from the manifold  5  constitute columns of the pressurizing chambers  10  equally spaced in the one direction of the flow channel member  4 , and 16 columns thereof are arranged parallel to one another in the transverse direction. The number of the pressurizing chambers  10  included in each of the pressurizing chamber columns corresponds to an outer shape of the displacement element  50  as the pressurizing part, and an arrangement is made so that the number thereof is gradually decreased from a long side of the outer shape to a short side thereof. The discharge holes  8  are arranged similarly. This ensures an image formation at a resolution of 600 dpi in one direction as a whole. 
     That is, when the discharge holes  8  are projected so as to be orthogonal to a virtual straight line parallel to the one direction of the flow channel member  4 , four discharge holes  8  connected to each of the sub manifold  5   a , namely, 16 discharge holes  8  in total are equally spaced of 600 dpi in a range R of a virtual straight line shown in  FIG. 9 . Individual flow channels  32  are connected at spaced intervals corresponding to 150 dpi on an average are connected to each of the sub manifolds  5   a . The reason for this is as follows. When a setting is made so that the discharge holes  8  corresponding to 600 dpi are dividingly connected to the sub manifolds  5   a  of the four columns, the individual flow channels  32  respectively connected to the sub manifolds  5   a  are not necessarily connected to one another at equally spaced intervals. Therefore, the individual flow channels  32  are formed at spaced intervals of not more than 170 μm on an average (spaced intervals of 25.4 mm/150=169 μm for 150 dpi) in an extending direction of the manifolds  5   a , namely, a main scanning direction. 
     Individual electrodes  35  described later are respectively formed at positions opposed to the pressurizing chambers  10  on an upper surface of the piezoelectric actuator substrate  21 . Each of the individual electrodes  35  is slightly smaller than the pressurizing chamber  10  and has a shape approximately similar to that of the pressurizing chamber  10 . The individual electrodes  35  are disposed so as to fall within a region of the upper surface of the piezoelectric actuator substrate  21  which is opposed to the pressurizing chambers  10 . 
     A large number of discharge holes  8  are formed on the liquid discharge surface  4   a  of a lower surface of the flow channel member  4 . These discharge holes  8  are disposed at positions other than a region opposed to the sub manifolds  5   a  disposed on the lower surface of the flow channel member  4 . 
     These discharge holes  8  are disposed in a region of the lower surface of the flow channel member  4  which is opposed to the piezoelectric actuator substrate  21 . These discharge holes  8  as a group occupy a region having approximately the same size and shape as the piezoelectric actuator substrate  21 . Liquid drops are dischargeable by displacing the displacement elements  50  of the corresponding piezoelectric actuator substrate  21 . The discharge holes  8  are arranged at equally spaced intervals along a plurality of straight lines parallel to the one direction of the flow channel member  4 . 
     The flow channel member  4  included in the head body  13  has a laminate structure having a plurality of plates laminated one upon another. These plates are a cavity plate  22 , a base plate  23 , an aperture plate  24 , supply plates  25  and  26 , manifold plates  27 ,  28 , and  29 , a cover plate  30 , and a nozzle plate  31  in descending order from the upper surface of the flow channel member  4 . A large number of holes are formed in these plates. These plates are positioned and laminated so that these holes are communicated with one another to constitute the individual flow channels  32  and the sub manifolds  5   a.    
     In the head body  13 , as shown in  FIG. 10 , the pressurizing chambers  10  are disposed on the upper surface of the flow channel member  4 , the sub manifolds  5   a  are disposed on the lower surface in the interior of the flow channel member  4 , and the discharge holes  8  are disposed on the lower surface of the flow channel member  4 . Thus, parts constituting the individual flow channels  32  are disposed close to one another at different positions so as to ensure that the sub manifolds  5   a  and the discharge holes  8  are connected to one another via the pressurizing chamber  10 . 
     The holes formed in the foregoing plates are described below. These holes can be classified into the following ones. Firstly, there is the pressurizing chamber  10  formed in the cavity plate  22 . Secondly, there is a communication hole constituting the flow channel extending from one end of the pressurizing chamber  10  to the sub manifold  5   a . This communication hole is formed in each of the plates, from the base plate  23  (specifically, an inlet of the pressurizing chamber  10 ) to the supply plate  25  (specifically, an outlet of the sub manifold  5   a ). This communication hole includes the aperture  12  that is formed on the aperture plate  24 , and the individual supply flow channel  6  formed on the supply plates  25  and  26 . 
     Thirdly, there is a communication hole constituting the flow channel that establishes communication from the other end of the pressurizing chamber  10  to the discharge hole  8 . This communication hole is hereinafter referred to as a descender (partial flow channel). The descender is formed in each of the plates, from the base plate  23  (specifically, an outlet of the pressurizing chamber  10 ) to the nozzle plate  31  (specifically, the discharge hole  8 ). 
     Fourthly, there is a communication hole constituting the sub manifold  5 . This communication hole is formed in the manifold plates  27  to  29 . 
     These communication holes are connected to one another to form the individual flow channel  32  that extends from the inlet for liquid from the sub manifold  5   a  (the outlet of the sub manifold  5   a ) to the liquid discharge hole  8 . The liquid supplied to the sub manifold  5   a  is discharged from the liquid discharge hole  8  through the following route. Firstly, the liquid proceeds upward from the sub manifold  5   a , passes through the individual supply flow channel  6  and reaches one end of the aperture  12 . The liquid then proceeds horizontally along an extending direction of the aperture  12  and reaches the other end of the aperture  12 . Subsequently, the liquid proceeds upward from there and reaches one end of the pressurizing chamber  10 . Further, the liquid proceeds horizontally along an extending direction of the pressurizing chamber  10  and reaches the other end of the pressurizing chamber  10 . The liquid then mainly proceeds downward while gradually moving from the other end of the pressurizing chamber  10  in a horizontal direction, and proceeds to the liquid discharge hole  8  being opened into the lower surface. 
     The piezoelectric actuator substrate  21  has a laminate structure formed of two piezoelectric ceramic layers  21   a  and  21   b  as shown in  FIG. 10 . Each of these piezoelectric ceramic layers  21   a  and  21   b  has a thickness of approximately 20 μm. An overall thickness of the piezoelectric actuator unit  21  is approximately 40 μm. Both the piezoelectric ceramic layers  21   a  and  21   b  are extended across a plurality of liquid pressurizing chambers  10  (refer to  FIG. 8 ). These piezoelectric ceramic layers  21   a  and  21   b  are formed of a ferroelectric lead zirconate titanate (PZT) based ceramic material. 
     The piezoelectric actuator substrate  21  includes a common electrode  34  formed of an Ag—Pd based metal material or the like, and the individual electrode  35  formed of an Au based metal material or the like. As described above, the individual electrode  35  is disposed at the position opposed to the pressurizing chamber  10  on the upper surface of the piezoelectric actuator substrate  21 . One end of the individual electrode  35  is led out beyond the region opposed to the pressurizing chamber  10  so as to form a connection electrode  36 . The connection electrode  36  is formed of, for example, silver-palladium containing glass frit, and is protrudedly formed with a thickness of approximately 15 μm. The connection electrode  36  is electrically connected to an electrode disposed on the flexible wiring board  92 . Although the details thereof are described later, a driving signal is supplied from the control section  100  to the individual electrode  35  via the flexible wiring board  92 . The driving signal is supplied on a fixed cycle in synchronization with a transport speed of a printing medium P. 
     The common electrode  34  is formed approximately over the entire surface in a planar direction in a region between the piezoelectric ceramic layer  21   a  and the piezoelectric ceramic layer  21   b . That is, the common electrode  34  extends to cover all the pressurizing chambers  10  in a region opposed to the piezoelectric actuator substrate  21 . The common electrode  34  has a thickness of approximately 2 μm. The common electrode  34  is grounded and held at ground potential in an unshown region. In the present embodiment, a surface electrode (not shown) different from the individual electrodes  35  is formed at a position that is kept away from an electrode group formed of the individual electrodes  35  on the piezoelectric ceramic layer  21   b . The surface electrode is electrically connected to the common electrode  34  via a through hole formed in the piezoelectric ceramic layer  21   b . Similarly to the large number of individual electrodes  35 , the surface electrode is connected to another electrode on the flexible wiring board  92 . 
     As shown in  FIG. 10 , the common electrode  34  and the individual electrode  35  are disposed so as to hold therebetween only the piezoelectric ceramic layer  21   b  that is the uppermost layer. A region in the piezoelectric ceramic layer  21   b  which is held between the individual electrode  35  and the common electrode  34  is referred to as an active area, and the piezoelectric ceramics corresponding to the active area is polarized. In the piezoelectric actuator substrate  21  of the present embodiment, only the uppermost piezoelectric ceramic layer  21   b  includes the active area, and the piezoelectric ceramic  21   a  does not include the active area and acts as a vibrating plate. The piezoelectric actuator substrate  21  has a so-called unimolf type configuration. 
     As described later, a predetermined driving signal is selectively applied to the individual electrode  35 , thereby applying a pressure to the liquid in the pressurizing chamber  10  corresponding to the individual electrode  35 . Consequently, liquid drops are discharged from the corresponding liquid discharge hole  8  through the individual flow channel  32 . That is, a portion of the piezoelectric actuator substrate  21  which is opposed to the pressurizing chamber  10  corresponds to the individual displacement element  50  (actuator) corresponding to the pressurizing chamber  10  and the liquid discharge hole  8 . Specifically, the displacement element  50 , whose unit structure is the structure as shown in  FIG. 10 , is fabricated into a laminate body formed of two piezoelectric ceramic layers in each of the pressurizing chambers  10  by using a vibrating plate  21   a , the common electrode  34 , the piezoelectric ceramic layer  21   b , and the individual electrode  35 , each of which is located immediately above the pressurizing chamber  10 . The piezoelectric actuator substrate  21  includes the displacement elements  50  that are the pressurizing parts. In the present embodiment, the amount of the liquid discharged from the liquid discharge hole  8  by a single discharge operation is approximately 5 to 7 pL (pico litter). 
     The large number of individual electrodes  35  are individually electrically connected to the control section  100  via the flexible wiring boards  92  and wiring so as to ensure individual control of potential. 
     When the individual electrode  35  is set at a different potential from that of the common electrode  34  and an electric field is applied to the piezoelectric ceramic layer  21   b  in a polarization direction thereof on the piezoelectric actuator substrate  21  of the present embodiment, a portion to which the electric field is applied acts as the active area that is distorted by piezoelectric effect. On this occasion, the piezoelectric ceramic layer  21   b  expands or contracts in a thickness direction, namely, lamination direction thereof, and attempts to contract or expand in a direction perpendicular to the lamination direction, namely, the planar direction by transverse piezoelectric effect. On the other hand, the rest of the piezoelectric ceramic layer  21   a  is a non-active layer that does not include the region held between the individual electrode  35  and the common electrode  34 , and therefore does not deform spontaneously. That is, the piezoelectric actuator substrate  21  has a so-called unimolf type configuration in which the piezoelectric ceramic layer  21   b  on an upper side (namely, a side away from the pressurizing chamber  10 ) is the layer including the active area, and the piezoelectric ceramic layer  21   a  on a lower side (namely, a side close to the pressurizing chamber  10 ) is the non-active layer. 
     When, in this configuration, the individual electrode  35  is set at a positive or negative predetermined potential with respect to the common electrode  34  by the control section  100  so that the electric field and the polarization are oriented in the same direction, a portion (active area) held between the electrodes of the piezoelectric ceramic layer  21   b  contracts in the planar direction. On the other hand, the piezoelectric ceramic layer  21   a  as the non-active layer is not affected by the electric field, and therefore does not contract spontaneously but attempts to restrict deformation of the active area. Consequently, a difference of distortion in the polarization direction occurs between the piezoelectric ceramic layer  21   b  and the piezoelectric ceramic layer  21   a , and the piezoelectric ceramic layer  21   b  is deformed so as to protrude toward the pressurizing chamber  10  (unimolf deformation). 
     According to an actual driving procedure in the present embodiment, the individual electrode  35  is previously set at a first voltage V 1  (V) (hereinafter “volt” is generally omitted) that allows the individual electrode  35  to have a higher potential than the common electrode  34 . Then, the individual electrode  35  and the common electrode  34  are temporarily set at a lower potential, for example, the same potential by applying a second voltage lower than the first voltage V 1  every time a discharge request is made, and thereafter are set again at a high potential at predetermined timing. This allows the piezoelectric ceramic layers  21   a  and  21   b  to return to their original shape at timing that the individual electrode  35  has a low potential, and the volume of the pressurizing chamber  10  is increased compared to its initial state (a state in which both electrodes have different potentials). On this occasion, a negative pressure is applied into the pressurizing chamber  10  and the liquid is absorbed from the manifold  5  into the pressurizing chamber  10 . 
     Thereafter, at the timing that the individual electrode  35  is set again at the high potential, the piezoelectric ceramic layers  21   a  and  21   b  are deformed so as to protrude toward the pressurizing chamber  10 . Due to a reduced volume of the pressurizing chamber  10 , the pressure in the pressurizing chamber  10  becomes a positive pressure and the pressure applied to the liquid is increased to discharge liquid drops. That is, the driving signal containing pulses using the high potential as a standard is supplied to the individual electrode  35  for the purpose of discharging the liquid drops. An ideal pulse width is an AL (acoustic length) that is a length of time during which a pressure wave propagates from the manifold  5  to the liquid discharge hole  8  in the pressurizing chamber  10 . Thereby, when a negative pressure state is reversed to a positive pressure state in the pressurizing chamber  10 , both pressures are combined together to allow the liquid drops to be discharged under a stronger pressure. 
     In a gradation printing, a gradation expression is made by the number of liquid drops to be continuously discharged from the discharge hole  8 , namely, the amount of liquid drops (volume) to be adjusted by the number of discharges of liquid drops. Therefore, the discharges of liquid drops, the number of which corresponds to a designated gradation expression, are continuously performed from the discharge hole  8  corresponding to a designated dot region. In general, when the liquid discharge is performed continuously, an interval between one pulse and another to be supplied for discharging the liquid drops is preferably set to the AL. This ensures that a cycle of a residual pressure wave of a pressure generated when discharging an early discharged liquid drop coincides with a cycle of a pressure wave of a pressure generated when discharging a later discharged liquid drop, and both are superimposed to amplify the pressure for discharging the liquid drops. In this case, the speed of the later discharged liquid drop seems to increase, however, this is preferred because landing points of a plurality of liquid drops become closer to each other. 
     Second Embodiment 
     A liquid discharge head  202  according to a second embodiment is described below with reference to  FIGS. 11 and 12 . Like parts bear the same reference characters, and the same applies to the following. 
     In the liquid discharge head  202 , a reservoir flow channel member  240  is formed of a first reservoir flow channel member  240   c  and a second reservoir flow channel member  240   d  surrounding the first reservoir flow channel member  240   c . The first reservoir flow channel member  240   c  forms the reservoir flow channel member  240  by being fitted into the second reservoir flow channel member  240   d . The first reservoir flow channel member  240   c  is an embodiment related to a first cover member of the present invention. The first cover member is described below by illustrating the reservoir flow channel member  240   c . The second reservoir flow channel member  240   d  is an embodiment related to a second cover member of the present invention. The second cover member is described below by illustrating the reservoir flow channel member  240   d.    
     The first reservoir flow channel member  240   c  has a reservoir flow channel (not shown) therein, and four recesses  240   e  on a side surface thereof. The second reservoir flow channel member  240   d  has an opening  243  at a central part thereof, and the first reservoir flow channel member  240   c  is disposed in the opening  243 . Therefore, a portion formed by the opening  243  of the second reservoir flow channel member  240   d  and the recess  240  of the first reservoir flow channel member  240   c  constitutes a hole  242  of the reservoir flow channel member  240 . 
     Thus in the liquid discharge head  202 , the reservoir flow channel member  240  is formed by the first reservoir flow channel member  240   c  and the second reservoir flow channel member  240   d , and the hole  242  is formed by the first reservoir flow channel member  240   c  and the second reservoir flow channel member  240   d.    
     The branch flow channel member  60  and the first reservoir flow channel member  240   c  are disposed on the head body  13 . The flexible wiring board  92  is inserted from the recess  240   e  of the first reservoir flow channel member  240   c , and the second reservoir flow channel member  240   d  is disposed outside the flexible wiring board  92 , thereby allowing the flexible wiring board  92  to be inserted into the hole  242 . This ensures easy assembly of the liquid discharge head  240  and also improves producibility of the liquid discharge head  2 . 
     As shown in  FIG. 12 , a positioning member  207  differs from the positioning member  7  in the shape of a positioning portion  207   d , and other portions are similar to those of the positioning member  7 . 
     In the positioning member  207 , a positioning portion  207   c  has an L-shape in a plan view, and the positioning portion  207   d  has a concave portion  207   e  at an end thereof. 
     A method of positioning the positioning member  207  is described below. Firstly, the concave portion  207   e  of the positioning portion  207   d  and one positioning pin  72   a  are brought into contact with each other. On this occasion, both are brought into contact with each other so as to establish contact between two sides constituting the concave portion  207   e  and the positioning pin  72   a.    
     Subsequently, the liquid discharge head  202  is rotated around the positioning pin  72   a  disposed so as to contact with the concave portion  207   e . Then, the liquid discharge head  202  is mounted on the printer by bringing the positioning pin  72   b  and the positioning portion  207   c  into contact with each other. 
     Thus, the positioning portion  207   d  has the concave portion  207   e , and the positioning pin  72   a  is disposed so as to contact with the concave portion  207   e . This reduces a deviation in one direction of the liquid discharge head  202 , and also strengthens connections between the liquid discharge head  202  and the positioning pins  72   a  and  72   b  during positioning. 
     Two screws  70  are disposed to fix the positioning member  207  and the second reservoir flow channel member  240   d  together, and the positioning pins  72   a  and  72   b  are disposed at positions between the two screws  70 , thereby further strengthening the connection between the liquid discharge head  202  and the positioning pins  72   a  and  72   b.    
     Third Embodiment 
     A third embodiment is described with reference to  FIG. 13 . A liquid discharge head  302  differs from the liquid discharge head  202  (refer to  FIG. 11 ) in the configuration of a reservoir flow channel member  340 .  FIG. 13( a )  shows only the reservoir flow channel member  340 . The housing  90  (refer to  FIG. 4 ) is omitted in  FIG. 13( b ) . 
     A first reservoir flow channel member  340   c  has four recesses  340   e  on a side surface thereof. A second reservoir flow channel member  340   d  has an opening  343  at a central part thereof. The first reservoir flow channel member  340   c  is disposed in the opening  343 . Therefore, a portion formed by the opening  343  of the second reservoir flow channel member  340   d  and the recesses  340   e  of the first reservoir flow channel member  340   c  constitutes a hole  342  of the reservoir flow channel member  340 . 
     The recesses  340   e  of the first reservoir flow channel member  340   c  are respectively provided with first protrusions  17   c  that protrude toward the hole  342 . The second reservoir flow channel member  340   d  has second protrusions  17   d  that protrude toward the hole  342 . 
     As shown in  FIG. 13( b ) , the first protrusions  17   c  and the second protrusions  17   d  are disposed at different heights. Although being unshown, the first protrusions  17   c  and the second protrusions  17   d  are respectively disposed in all the four holes  342 . 
     Accordingly, each of the flexible wiring boards  92  is to be pressed by the first protrusions  17   c  and the second protrusions  17   d  when being inserted through the hole  342 . Consequently, as shown in  FIG. 13( b ) , the flexible wiring board  92  becomes bendable and functions to bury the hole  442 , thereby reducing the possibility that ink intrudes into the interior of the liquid discharge head  302 . 
     Particularly, even when ink in mist state floats in the vicinity of the holes  342 , the ink that has intruded into the holes  442  is to contact with the flexible wiring boards  92  over a wide area at bent portions of the flexible wiring boards  92 , thus allowing the ink to attach to the flexible wiring boards  92 . It is therefore possible to prevent intrusion of the ink into the interior of the liquid discharge head  302 . 
     The first protrusions  17   c  and the second protrusions  17   d  are preferably disposed so as to close the holes  342  in a plan view. That is, a sum of a width of the first protrusion  17   c  and a width of the second protrusion  17   d  is made longer than a width of the hole  342  in the plan view. This configuration allows the flexible wiring boards  92  to be surely bent, thus reducing the possibility of the intrusion of the ink. 
     The foregoing illustrates, by way of example, the case where the liquid discharge head  302  includes the first protrusions  17   c  and the second protrusions  17   d , but examples of the liquid discharge head are not limited to this. For example, the first reservoir flow channel member  320   c  may have only the first protrusions  17   c . The second reservoir flow channel member  320   d  may have only the second protrusion  17   d . These configurations also allow the flexible wiring boards  92  to be bent, thus reducing the possibility of the intrusion of the ink. 
     A plurality of the first protrusions  17   c  and a plurality of the second protrusions  17   d  may be disposed, which are preferably disposed alternately in a cross sectional view. By alternately disposing the first protrusions  17   c  and the second protrusions  17   d  in the cross sectional view, the number of bending of the flexible wiring boards  92  can be increased to further reduce the possibility of the intrusion of the ink. 
     That is, even when mist-state ink intrudes into the holes  342 , the flexible wiring boards  92  are bent a plurality of times, thus making it possible to increase the number of contacts between the mist-state ink and the flexible wiring boards  92  and the holes  342 . This reduces the possibility that the ink intrudes into the interior of the liquid discharge head  302 . 
     Even when the ink attaches to the flexible wiring boards  92  and the attached ink flows downward, the positioning member  307 , the first protrusions  17   c  and the second protrusions  17   d  are capable of damming up the flow of the ink flowing downward, thereby reducing the possibility that the ink intrudes into the interior of the liquid discharge head  302 . 
     Although the foregoing illustrates the configuration that the first protrusions  17   c  and the second protrusions  17   d  extend along one direction of the liquid discharge head  302 , a similar effect is attainable in the case of intermittently disposing the first protrusions  17   c  and the second protrusions  17   d.    
     Although the foregoing illustrates the case where the first protrusions  17   c  are disposed on the first reservoir flow channel  342   c  and the second protrusions  17   d  are disposed on the second reservoir flow channel  342   d , only either of them may be disposed. 
     Fourth Embodiment 
     A fourth embodiment is described with reference to  FIG. 14 . The fourth embodiment differs from the foregoing embodiments in the configurations of a positioning member  407  and a reservoir flow channel member  440 . 
     As shown in  FIG. 14( b ) , the positioning member  407  has a flange  407   f  disposed on a coupling portion  407   b . The flange  407   f  is disposed on a portion of the coupling portion  407   b  which is close to an opening  407   a . This ensures that the flexible wiring boards  92  are held between a frame  96  and the flange  407   f . Consequently, even when ink attaches to the flexible wiring boards  92  and the attached ink flows downward, the flange  407   f  is capable of suppressing the intrusion of the ink. 
     Owing to the flange  407   f  provided on the positioning member  407 , contacts between the flexible wiring boards  92  and the positioning member  407  contribute to reducing the possibility that the flexible wiring board  92  are subjected to wear. 
     The positioning member  407  has the flange  407   f  on the coupling portion  407   b , thus making it possible to enhance the rigidity of the coupling portion  407   b . Consequently, the positioning portions  407   c  and  407   d  are unsusceptible to deformation, thus leading to improved positioning accuracy. 
     The reservoir flow channel member  440  has a protrusion  444  on an upper surface thereof. The protrusion  444  is disposed in the interior of an opening  7   a  of the positioning member  7 . A substrate  94  is disposed on an upper surface of the protrusion  444 . Covering members  51  are respectively disposed so as to cover holes  442  of the reservoir flow channel member  440 . 
     In addition to covering the holes  442  with the flexible wiring boards  92  and the positioning member  7 , the holes  442  are respectively further covered with the covering members  51 , thereby further improving sealability. 
     In a liquid discharge head  402 , each of the covering members  51  is disposed so as to seal a clearance between the hole  442  of the reservoir flow channel member  440  and the flexible wiring board  92 . More specifically, the covering members  51  are disposed so as to cover the coupling portion  407   b  of the positioning member  407 . 
     Owing to the coupling portion  407   b  of the positioning member  407  disposed above the holes  442  of the reservoir flow channel member  440 , the holes  442  are to be led out upward after the flexible wiring boards  92  are pressed and bent. Therefore, when mist-state ink intrudes from an arrowed direction A shown in  FIG. 14( b ) , the intrusion of the ink is preventable by the bent flexible wiring boards  92 . 
     Owing to the covering members  51  disposed so as to cover the coupling portion  407   b  from the outside of the opening  407   a , when the mist-state ink intrudes from an arrowed direction B shown in  FIG. 14( b ) , the intrusion of the ink is preventable by the covering members  51 . 
     That is, with such a configuration that the flexible wiring boards  92  are inserted from the inside of the opening  407   a  and the covering members  51  are disposed so as to cover the coupling portion  407   b  from the outside of the opening  407   a , it is possible to reduce the possibility that the mist-state ink intrudes up to the head body  13 . 
     The covering members  51  are capable of strengthening connection between the coupling portion  7   b  of the positioning member  7  and a first member  16 . 
     With the configuration that the covering members  51  are disposed so as to cover the coupling portion  407   b  from the outside of the opening  407   a , the covering members  51  can be coated after the flexible wiring boards  92  are pressed by the positioning member  407 , thereby improving the sealability of the holes  442 . Additionally, it is easy to coat the covering members  51 , thereby improving working efficiency in manufacturing processes of the inkjet head  2 . 
     Examples of the covering members  51  include thermosetting resin, silicone, and UV-curable resin. The covering members  51  are preferably formed by a heat releasing member using a heat releasing resin or a resin incorporating heat releasing particles, such as metal particles. 
     By forming the covering members  51  using the heat releasing member, when heat of the driver ICs  55  generated during driving is subjected to heat conduction via internal wiring (not shown) of the flexible wiring boards  92 , the heat is subjected to heat conduction to the covering members  51  so as to be released to other member. More effective heat release is attainable when the positioning member  407  is formed of a metal or alloy having high thermal conductivity. 
     In the present embodiment, a displacement element  50  using piezoelectric deformation is illustrated as the pressurizing part, without being limited thereto. It is possible to employ another one that can pressurize liquid in the pressurizing chambers  10 . There are, for example, one that generates pressure by heating and boiling the liquid in the pressurizing chambers  10 , and one that uses MEMS (micro electro mechanical systems). 
     Although the case of using the reservoir flow channel member  40  as the first member has been described above, a cover member having no flow channel therein may be used instead of the reservoir flow channel member  40 . For example, the liquid discharge head  2  may be configured to supply the liquid from the exterior to the liquid inlet hole  5   b  of the manifold  5  through a tube or the like. In this case, the first member needs to have the function of protecting the piezoelectric actuator substrate  21 . Also in this case, the holes  42  can be covered with the positioning member  7  and the flexible wiring boards  92 , thus leading to equivalent effect. 
     Although the foregoing illustrates the case of using the positioning member  7  as the second member, for example, a lid member for covering the holes  42  may be employed instead of the positioning member  7 . Alternatively, the positioning member  7  may be one in which the positioning portions  7   c  and  7   d  are not connected to each other by the coupling portion  7   b . For example, the positioning member  7  may be one in which the positioning portions  7   c  and  7   d  are formed separately. 
     The present embodiment illustrates, by way of example, the case where the flexible wiring boards  92  and the positioning member  7  are in contact with each other. The positioning member  7  needs to be located above the holes  42 , and the flexible wiring boards  92  and the positioning member  7  may not be in contact with each other. Also in this case, the positioning member  7  located above the holes  42  is capable of reducing the possibility that the mist-state ink intrudes from above into the holes  42 , thereby reducing the possibility of the intrusion of the ink into the interior of the liquid discharge head  2 . 
     A clearance may exist between the reservoir flow channel member  40  and the flexible wiring boards  92  and between the positioning member  7  and the flexible wiring boards  92 . Also in this case, because most of the mist-state ink can intrude from above the holes  42 , the positioning member  7  located above the holes  42  is capable of reducing the possibility that the mist-state ink intrudes from above into the holes  42 , thereby reducing the possibility of the intrusion of the ink into the interior of the liquid discharge head  2 . 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           1  printer 
           2  liquid discharge head 
           4  flow channel member 
           4   a  discharge hole surface 
           4   b  pressurizing chamber surface 
           5  manifold (common flow channel) 
           5   a  sub manifold 
           5   b  opening of manifold (liquid inlet hole) 
           5   c  liquid supply passage 
           6  individual supply flow channel 
           7  positioning member 
           7   a  opening 
           7   b  coupling portion 
           7   c  positioning portion 
           7   d  positioning portion 
           8  discharge hole 
           9  pressurizing chamber group 
           10  pressurizing chamber 
           12  aperture 
           15   a ,  15   b ,  15   c ,  15   d  discharge hole column 
           17  protrusion 
           17   c  first protrusion 
           17   d  second protrusion 
           21  piezoelectric actuator substrate 
           22 - 31  plate 
           32  individual flow channel 
           34  common electrode 
           35  individual electrode 
           36  connection electrode 
           40  reservoir flow channel member 
           40   a  reservoir flow channel member body 
           40   b  plate 
           40   c  first reservoir flow channel member 
           40   d  second reservoir flow channel member 
           41  reservoir flow channel 
           42  hole 
           43  side surface protection plate 
           45  filter 
           47  damper 
           50  displacement element (pressurizing part) 
           51  covering member 
           60  branch flow channel member 
           60   a - 60   c  plate 
           61  branch flow channel 
           90  housing 
           90   c  hole 
           92  flexible wiring board 
           94  substrate 
           95  connector 
           96  frame 
           97  heat insulation elastic member