Patent Publication Number: US-7585057-B2

Title: Method of manufacturing ink-jet head

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of manufacturing an ink-jet head that ejects ink from an ink ejection port. 
     2. Description of Related Art 
     A known ink-jet head has a passage unit and a piezoelectric actuator bonded to the passage unit. The passage unit has an individual ink passage including an ink ejection port and a pressure chamber. The piezoelectric actuator applies pressure to ink contained in the pressure chamber. In some ink-jet heads of this type, on a surface of a piezoelectric actuator, an electrode is electrically connected to a wire member through which a drive signal is supplied to the electrode so that the piezoelectric actuator is driven. For example, U.S. Patent Application Publication No. 20040113994 discloses an ink-jet head in which an actuator unit acting as a piezoelectric actuator includes a piezoelectric body having four laminated piezoelectric layers, and conductive lands are provided on upper faces of respective individual electrodes that are formed on the piezoelectric body. Each of the lands is formed by printing a metal paste, such as a gold paste, in a pattern on the individual electrode and then baking the paste. The individual electrodes formed on the actuator unit are, through the lands, electrically connected to wire terminals formed on an FPC (Flexible Printed Circuit) which is a wire member disposed above the actuator unit. Only at the lands, the actuator unit is in contact with the FPC. The piezoelectric body and the FPC are sufficiently spaced apart by the lands sandwiched therebetween, so that they are not in contact with each other. Therefore, deformation of the piezoelectric body is not hindered by the FPC, and thus performance of ink ejection from ink ejection ports does not change. 
     SUMMARY OF THE INVENTION 
     However, in order to manufacture the ink-jet head disclosed in U.S. Patent Application Publication No. 20040113994, it is necessary that the lands made of the metal paste are baked at a high temperature. In such a baking process, the piezoelectric body may be warped, or a metal may be scattered inside the piezoelectric body to consequently deteriorate insulation resistance of the piezoelectric body. In addition, since a material such as gold is expensive, manufacturing costs increase. A possible way of solving the problems is to use, as a material of the lands, a resin paste including a conductive material bakeable at a low temperature, instead of the metal material. However, a resin paste is softer than a metal. Therefore, if, after the lands are formed, the piezoelectric actuator is pressed to the passage unit to bond them, the lands are crushed and their height is lowered. As a result, the piezoelectric body and the FPC cannot sufficiently be spaced apart from each other. Alternatively, in a case where heights of lands are uneven, a land having a larger height is pressed and it upper face is flattened. Such a land may become a defective contact. In order to avoid these drawbacks, it is conceivable that the lands are formed after the passage unit and the piezoelectric actuator are bonded to each other. However, pressure chambers are configured as recesses that are formed on a surface of the passage unit. Thus, a lower face of the piezoelectric actuator is partially supported on the passage unit, and partially not supported on the passage unit but opposed to the pressure chambers. In a case where, like this, the lower face of the piezoelectric actuator is partially supported on the passage unit, cracking may occur in the piezoelectric body due to force that is applied to the piezoelectric body at the time of printing the resin paste in a pattern on surfaces of the individual electrodes. 
     An object of the present invention is to provide a method of manufacturing an ink-jet head that can ensure a sufficient space between a piezoelectric body and a wire member while preventing occurrence of warping of the piezoelectric body, deterioration in insulation resistance of the piezoelectric body, and cracking in the piezoelectric body. 
     According to an aspect of the present invention, there is provided a method of manufacturing an ink-jet head comprising a passage unit, a piezoelectric actuator, and a wire member. The passage unit has an individual ink passage including an ink ejection port and a pressure chamber, and also has a surface on which the pressure chamber is provided in a form of a recess. The piezoelectric actuator applies ejection energy to ink in the pressure chamber. The piezoelectric actuator includes a piezoelectric body that is disposed on the surface of the passage unit to thereby close the recess, an electrode that is formed, so as to be opposed to the pressure chamber, on a surface of the piezoelectric body facing against the passage unit, and a conductive land that is formed on the electrode. The wire member includes a substrate and a wiring formed on the substrate and provided thereon with a terminal electrically connected to the land. The method comprises the steps of: forming, on the electrode, the land made of a resin paste including a conductive material, in a state where a whole of a face of the piezoelectric actuator opposite to a face thereof formed with the land is supported on a support member; bonding the passage unit and the piezoelectric actuator to each other by pressing the land except a part thereof in a state where the piezoelectric actuator is disposed on the surface of the passage unit with the electrode being opposed to the pressure chamber; and electrically connecting the land to the terminal by bringing the part of the land not pressed in the step of bonding into contact with the wire member. 
     In the aspect, the land is made of the resin paste. It is therefore not necessary to bake the land at a high temperature when forming the land. This can suppress warping of the piezoelectric body, and scattering of a conductive material included in the land into the piezoelectric body which deteriorates insulation resistance of the piezoelectric body. In addition, since the land is made of the resin paste, manufacturing costs can be reduced as compared with when the land is made of a metal material such as gold. 
     Besides, since the land is formed on the piezoelectric actuator before the piezoelectric actuator is bonded to the passage unit, the land can be formed under a state where the whole of the face of the piezoelectric actuator opposite to a face thereof formed with the land is supported on the support member. This makes it difficult that cracking occurs in the piezoelectric body. 
     Moreover, when bonding the piezoelectric actuator to the passage unit, the land is pressed except a part thereof. Therefore, the part of the land is not crushed due to a bonding press. Thus, the part of the land is not reduced in height, so that a sufficient space is ensured between the piezoelectric body and the wire member. This can prevent ejection failure which may otherwise be caused by occurrence of contact between the wire member and the piezoelectric body. 
     Further, an upper face of the unpressed part of the land is not flat. Therefore, when electrically connecting the land to the terminal, unevenness of a height of the land can be absorbed, so that the land and the terminal can surely be connected to each other. 
     Still further, when bonding the piezoelectric actuator to the passage unit, the piezoelectric body is not directly pressed but indirectly pressed with the land therebetween. Therefore, even if a small foreign matter exists between the piezoelectric body and the jig or a small protrusion exists on the surface of the piezoelectric body, occurrence of cracking or the like in the piezoelectric body can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other and further objects, features and advantages of the invention will appear more fully from the following description taken in connection with the accompanying drawings in which: 
         FIG. 1  schematically illustrates a construction of an ink-jet printer having ink-jet heads manufactured by the method according to an embodiment of the present invention; 
         FIG. 2  is a plan view of a head main body that is illustrated in  FIG. 1 ; 
         FIG. 3  is a partial view of  FIG. 2  on an enlarged scale; 
         FIG. 4  is a sectional view taken along line IV-IV in  FIG. 3 ; 
         FIG. 5  is a partial view of  FIG. 4  on an enlarged scale, including an FPC; 
         FIG. 6  is a diagram schematically showing a positional relationship in a plan view between a land of a piezoelectric actuator and a wire terminal of the FPC; 
         FIGS. 7A to 7D  are sectional views showing step by step a method of manufacturing the ink-jet head that is illustrated in  FIG. 1   
         FIGS. 8A and 8B  are sectional views corresponding to  FIGS. 7C and 7D , respectively, and showing a manufacturing method according to a first modification of the embodiment of the present invention; 
         FIGS. 9A and 9B  are sectional views corresponding to  FIGS. 7C and 7D , respectively, and showing a manufacturing method according to a second modification of the embodiment of the present invention; 
         FIGS. 10A and 10B  are sectional views corresponding to  FIGS. 7C and 7D , respectively, and showing a manufacturing method according to a third modification of the embodiment of the present invention; 
         FIG. 11  is a sectional view corresponding to  FIG. 7B , and showing a manufacturing method according to a fourth modification of the embodiment of the present invention; and 
         FIG. 12  is a sectional view corresponding to  FIG. 7B , and showing a manufacturing method according to a fifth modification of the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will be given to an ink-jet head manufactured by a method according to an embodiment of the present invention.  FIG. 1  illustrates a printer  1  that includes ink-jet heads  2  manufactured by the method according to this embodiment. The printer  1  illustrated in  FIG. 1  is a color ink-jet printer of line-head type, which includes four fixed ink-jet heads  2 . In a plan view, the ink-jet head  2  has a rectangular shape elongated in a direction perpendicularly crossing the drawing sheet of  FIG. 1 . The printer  1  includes a paper feed unit  114 , a paper discharge tray  116 , and a conveyance unit  120 , which are shown in lower, upper, and middle parts of  FIG. 1 , respectively. The printer  1  also includes a controller  100  that controls operations of the above-mentioned units. 
     The paper feed unit  114  has a paper holder  115  and a paper feed roller  145 . A stack of printing papers (recording media) P of rectangular shape can be held in the paper holder  115 . The paper feed roller  145  sends out to the conveyance unit  120  an uppermost one of the printing papers P held in the paper holder  115 . In the paper holder  115 , the printing paper P is held so as to be sent out in a direction along its longer side. Two pairs of feed rollers  118   a  and  118   b , and  119   a  and  119   b  are disposed along a conveyance path between the paper holder  115  and the conveyance unit  120 . The printing paper P discharged from the paper feed unit  114  is, with one shorter side thereof being a leading edge, sent upward in  FIG. 1  by the feed rollers  118   a  and  118   b . Then, by the feed rollers  119   a  and  119   b , the printing paper P is sent leftward to the conveyance unit  120 . 
     The conveyance unit  120  has an endless conveyor belt  111 , and two belt rollers  106  and  107  on which the conveyor belt  111  is wound. A length of the conveyor belt  111  is adjusted in such a manner that a predetermined tension occurs in the conveyor belt  111  in a state where the conveyor belt  111  is wound on the two belt rollers  106  and  107 . The conveyor belt  111 , which is wound on the two belt rollers  106  and  107 , has two parallel planes each including a tangent line common to the belt rollers  106  and  107 . One of the two planes opposed to the ink-jet heads  2  forms a conveyor face  127  for the printing paper P. On the conveyor face  127  formed by the conveyor belt  111 , the printing paper P sent out of the paper feed unit  114  is conveyed while the ink-jet heads  2  perform printing on an upper face (printing face) of the printing paper P. Then, the printing paper P reaches the paper discharge tray  116 . The printing papers P thus printed are piled in the paper discharge tray  116 . 
     Each of the four ink-jet heads  2  has a head main body  13  at its lower end. The head main body  13  is made of a passage unit  4  and four piezoelectric actuators  21  that are bonded to the passage unit  4  with an adhesive (see  FIGS. 2 and 4 ). As will be described later, many individual ink passages  32  each including an ink ejection port  8  and a pressure chamber  10  are formed inside the passage unit  4 . Pressure is applied to ink in the pressure chamber  10 . The piezoelectric actuator  21  applies pressure to ink contained in desired one(s) of many pressure chambers  10 . Bonded to an upper face of each piezoelectric actuator  21  is an FPC  50  acting as a wire member that supplies a printing signal to the piezoelectric actuator (see  FIG. 5 ). 
     In a plan view, as shown in  FIG. 2 , the head main body  13  has a rectangular shape elongated in a direction perpendicularly crossing the drawing sheet of  FIG. 1 . The four head main bodies  13  are arranged adjacent to each other along a horizontal direction of the drawing sheet of  FIG. 1 . Each of the four head main bodies  13  has, on its bottom face (ink ejection face), many small-diameter ink ejection ports  8 , as shown in  FIG. 3 . A color of ink ejected from the ink ejection port  8  is any of magenta (M), yellow (Y), cyan (C), and black (K). Many ink ejection ports  8  included in one head main body  13  eject ink of the same color. Besides, the four head main bodies  13  eject, from their many ink ejection ports  8 , ink of four different colors of magenta, yellow, cyan, and black, respectively. 
     A narrow space is formed between the bottom faces of the head main bodies  13  and the conveyor face  127  of the conveyor belt  111 . The space constitutes a conveyance path along which the printing paper P is conveyed from right to left in  FIG. 1 . While the printing paper P passes under the four head main bodies  13 , ink is ejected from the ink ejection ports  8  toward the upper face of the printing paper P in accordance with image data, so that a desired colored image is formed on the printing paper P. 
     The two belt rollers  106  and  107  are in contact with an inner surface  111   b  of the conveyor belt  111 . Among the two belt rollers  106  and  107  of the conveyance unit  120 , the belt roller  106  which locates downstream in the conveyance path is connected to a drive shaft  174  of an unillustrated conveyor motor. The conveyor motor is driven in rotation under control of the controller  100 . The other belt roller  107  is a slave roller that is rotated by rotational force given by the conveyor belt  111  along with rotation of the belt roller  106 . 
     A nip roller  138  and a nip bearing roller  139  are disposed near the belt roller  107 , so as to sandwich the conveyor belt  111  therebetween. The nip roller  138  is biased downward by an unillustrated spring, in order to press, to the conveyor face  127 , the printing paper P supplied to the conveyance unit  120 . The conveyor belt  111  and the printing paper P are nipped between the nip roller  138  and the nip bearing roller  139 . Since an outer surface of the conveyor belt  111  is treated with adherent silicone rubber, the printing paper P surely adheres to the conveyor face  127 . 
     As shown in  FIG. 1 , a peeling plate  140  is provided on a left side of the conveyance unit  120 . A right end of the peeling plate  140  goes into between the printing paper P and the conveyor belt  111 , thereby peeling the printing paper P, which adheres to the conveyor face  127  of the conveyor belt  111 , from the conveyor face  127 . 
     Two pairs of feed rollers  121   a  and  121   b , and  122   a  and  122   b  are disposed between the conveyance unit  120  and the paper discharge tray  116 . The printing paper P discharged from the conveyance unit  120  is, with one shorter side thereof being a leading edge, sent upward in  FIG. 1  by the feed rollers  121   a  and  121   b . Then, the printing paper P is sent to the paper discharge tray  116  by the feed rollers  122   a  and  122   b.    
     A paper sensor  133 , which is an optical sensor made up of a light emitting body and a light receiving body, is disposed between the nip roller  138  and the most upstream one of the ink-jet heads  2 , in order to detect a position of the leading edge of the printing paper P on the conveyance path. 
     Next, details of the head main body  13  will be described.  FIG. 2  is a plan view of the head main body  13  illustrated in  FIG. 1 .  FIG. 3  is a plan view, on an enlarged scale, of a block enclosed with an alternate long and short dash line in  FIG. 2 . In  FIG. 3 , for the purpose of easy understanding, the piezoelectric actuators  21  are illustrated with broken lines though they should be illustrated with solid lines, while ink ejection ports  8 , pressure chambers  10 , and apertures  12 , which actually should be illustrated with broken lines, are illustrated with solid lines. 
     As shown in  FIGS. 2 and 3 , the head main body  13  has a passage unit  4  in which formed are many pressure chambers  10  and many ink ejection ports  8 . The many pressure chambers  10  form four pressure chamber groups  9 . Pressure is applied to ink in the respective pressure chambers  10 , thus ejecting the ink from the many ink ejection ports  8 . Four piezoelectric actuators  21  of trapezoidal shape are bonded to an upper face of the passage unit  4 . The piezoelectric actuators  21  are arranged in two rows and in a zigzag pattern along a longitudinal direction of the passage unit  4 . To be more specific, each of the piezoelectric actuators  21  is disposed with its parallel opposed sides, that is, its upper and lower sides, extending along the longitudinal direction of the passage unit  4 . In addition, oblique sides of every neighboring piezoelectric actuators  21  partially overlap each other with respect to a widthwise direction of the passage unit  4 . 
     Regions of a lower face of the passage unit  4  corresponding to where the piezoelectric actuators  21  are bonded define ink ejection regions. As shown in  FIG. 3 , many ink ejection ports  8  are regularly arranged in the ink ejection regions. On the upper face of the passage unit  4 , many pressure chambers  10  are regularly arranged in two dimensions (in a matrix). The pressure chambers  10  are configured as recesses that are formed on the upper face of the passage unit  4 . The recesses are closed with the piezoelectric actuators  21 , so that the pressure chambers  10  are defined. As a result, a lower face of the piezoelectric actuator  21  is partially supported on the passage unit  4 , and partially not supported on the passage unit  4  but opposed to the pressure chambers  10 . 
     In the upper face of the passage unit  4 , one pressure chamber group  9  is made up of pressure chambers  10  that exist within a region opposed to one piezoelectric actuator  21 . As will be described later, an individual electrode  35  formed on the piezoelectric actuator  21  is opposed to each pressure chamber  10  in one-to-one correspondence. 
     Manifold channels  5  acting as common ink chambers, and sub manifold channels  5   a  acting as branch passages of the common ink chambers, are formed inside the passage unit  4 . One ink ejection region is opposed to four sub manifold channels  5   a  which extend in the longitudinal direction of the passage unit  4 . Through ink flow-in openings  5   b  provided on the upper face of the passage unit  4 , ink is supplied to the manifold channels  5 . 
     Ink goes through an outlet of the sub manifold channel  5   a , then through an aperture  12  which acts as a throttle and a pressure chamber  10  which has a substantially rhombic shape in a plan view, and then ejected from an ink ejection port  8 . Rows of ink ejection ports  8  extend in the longitudinal direction of the passage unit  4 . Ink that is ejected from ink ejection ports  8  included in four neighboring rows is supplied from the same sub manifold channel  5   a.    
     The many ink ejection ports  8  of the passage unit  4  are positioned in such a manner that their projective points on an imaginary line extending in the longitudinal direction of the passage unit  4  (i.e., extending perpendicularly to the paper conveyance direction) can be arranged at regular intervals of 600 dpi, when all of them are projected onto the imaginary line in a direction perpendicular to the imaginary line. 
     A cross-sectional structure of the head main body  13  will be described.  FIG. 4  is a sectional view taken along line IV-IV in  FIG. 3 . As shown in  FIG. 4 , the head main body  13  is made of the passage unit  4  and the piezoelectric actuator  21  bonded to each other. The passage unit  4  has a layered structure in which, from the top, a cavity plate  22 , a base plate  23 , an aperture plate  24 , a supply plate  25 , manifold plates  26 ,  27 ,  28 , a cover plate  29 , and a nozzle plate  30  are put in layers. Formed inside the passage unit  4  are ink passages extending to the ink ejection ports  8  at which ink supplied from outside is ejected as ink droplets. The ink passages include the manifold channels  5  and the sub manifold channels  5   a  that temporarily store ink therein, and also include individual ink passages  32  each extending from an outlet of the sub manifold channel  5   a  to an ink ejection port  8 . Recesses and holes, which constitute parts of the ink passages, are formed in the respective plates  22  to  30 . 
     The cavity plate  22  is a metal plate in which formed are many substantially rhombic holes serving as pressure chambers  10 . The base plate  23  is a metal plate in which formed are many connection holes each connecting each pressure chamber  10  to a corresponding aperture  12  and many connection holes each constituting a part of a passage from each pressure chamber  10  to a corresponding ink ejection port  8 . The aperture plate  24  is a metal plate in which formed are many holes serving as apertures  12  and many connection holes each constituting a part of a passage from each pressure chamber  10  to a corresponding ink ejection port  8 . The supply plate  25  is a metal plate in which formed are many connection holes each connecting each aperture  12  to a sub manifold channel  5   a  and many connection holes each constituting a part of a passage from each pressure chamber  10  to a corresponding ink ejection port  8 . Each of the manifold plates  26 ,  27 , and  28  is a metal plate in which formed are holes constituting sub-manifold channels  5   a  and many connection holes each constituting a part of a passage from each pressure chamber  10  to a corresponding ink ejection port  8 . The cover plate  29  is a metal plate in which formed are many connection holes each constituting a part of a passage from each pressure chamber  10  to a corresponding ink ejection port  8 . The nozzle plate  30  is a metal plate in which many through holes are formed. The through holes constitute ink ejection ports  8  on an outside face of the nozzle plate  30 . The nine metal plates are positioned in layers so as to form individual ink passages  32 . 
     As shown in  FIG. 5 , the piezoelectric actuator  21  includes a piezoelectric body  45  having a layered structure of four piezoelectric layers  41 ,  42 ,  43  and  44 . Each of the piezoelectric layers  41  to  44  has the same thickness of approximately 15 μm, and thus the piezoelectric actuator  21  has a thickness of approximately 60 μm. Any of the piezoelectric layers  41  to  44  is a continuous layer-like flat plate (continuous flat layer) extending over all the pressure chambers  10  formed in one ink ejection region of the head main body  13 . The piezoelectric layers  41  to  44  are made of a lead zirconate titanate (PZT)-base ceramic material having ferroelectricity. 
     An individual electrode  35  having a thickness of approximately 1 μm is formed on the uppermost piezoelectric layer  41 . The individual electrode  35  and a later-described common electrode  34  are formed by printing a conductive paste that includes a conductive material such as a metal. The individual electrode  35  has a substantially rhombic shape in a plan view. The individual electrode  35  is formed so that it is opposed to the pressure chamber  10  and besides its most part falls within the pressure chamber  10  in a plan view. Consequently, substantially over a whole area on the uppermost piezoelectric layer  41 , many individual electrodes  35  are regularly arranged in two dimensions in the same pattern as that of the pressure chambers  10 , as shown in  FIG. 3 . In this embodiment, the individual electrodes  35  are formed only on a surface of the piezoelectric actuator  21 , and therefore only the outermost piezoelectric layer  41  includes active regions that cause piezoelectric strain. The other piezoelectric layers  42 ,  43 , and  44  are inactive layers. Accordingly, the piezoelectric actuator  21  is an actuator that has active and inactive layers laminated and causes unimorph deformation, thus presenting a good efficiency of deformation. 
     One acute portion of the individual electrode  35  is not opposed to the pressure chamber  10 . Specifically, the one acute portion extends to a position above a beam  22   a  of the cavity plate  22  which means a portion of the cavity plate  22  where the pressure chamber  10  is not formed. The beam  22   a  is bonded to and supports the piezoelectric actuator  21 . A land  36  made of a conductive resin paste is provided on a portion of the individual electrode  35  not opposed to the pressure chamber  10 . The land  36  has a diameter of approximately 30 μm in a plan view. The individual electrode  35  and the land  36  are electrically connected to each other. The land  36  has a substantially circular shape in a plan view. As shown in  FIG. 5 , a central portion of the land  36  forms a protrusion  36   a  that protrudes above a peripheral portion  36   b  surrounding the protrusion  36   a . The protrusion  36   a  has a diameter of approximately 15 μm in a plan view. As will be detailed later, each land  36  is electrically connected, through a wiring  53  provided on the FPC  50 , to an unillustrated driver IC which is a part of the controller  100 . 
     A common electrode  34  having a thickness of approximately 2 μm is interposed between the uppermost piezoelectric layer  41  and the piezoelectric layer  42  disposed under the uppermost piezoelectric layer  41 . The common electrode  34  is formed substantially over an entire face of the piezoelectric actuator  21 . As a result, the piezoelectric layer  41  is, in its portion opposed to the pressure chamber  10 , sandwiched between a pair of electrode including the individual electrode  35  and the common electrode  34 . An electrode is disposed neither between the piezoelectric layers  42  and  43  nor between the piezoelectric layers  43  and  44 . 
     On the piezoelectric layer  41 , an unillustrated surface electrode is formed outside an electrode group made up of the individual electrodes  35 . The surface electrode is electrically connected to the common electrode  34  through an unillustrated conductive member that is embedded in a through hole formed in the piezoelectric layer  41 . In addition, the surface electrode is also connected to an unillustrated wiring provided on the FPC  50 . Through the wiring, the common electrode  34  is grounded. Consequently, the common electrode  34  is, in its portions corresponding to all the pressure chambers  10 , equally kept at the ground potential. An unillustrated land having the same shape as that of the land  36  is provided on the surface electrode. 
     As shown in  FIG. 5 , the FPC  50  acting as a wire member is disposed above the piezoelectric actuator  21 . The FPC  50  has an insulating substrate  51 , a wiring  53  formed on the substrate  51  in a pattern, and a covering layer  52  sandwiching the wiring  53  with the substrate  51  to thereby protect the wiring  53 . A through hole  52   a  having a diameter of approximately 17 μm is formed at a portion of the covering layer  52  overlapping in a plan view the protrusion  36   a  of each land  36 . The wiring  53  is exposed at a bottom of the through hole  52   a , and an exposed region of the wiring  53  serves as a terminal  53   a  having a diameter of approximately 17 μm. The terminal  53   a  is electrically bonded to an end of the protrusion  36   a  of the land  36 , so that the individual electrode  35  and the wiring  53  are electrically connected through the land  36 .  FIG. 6  shows a positional relationship in a plan view between the land  36  and the terminal  53   a.    
     A side face of the land  36  is covered with a synthetic resin layer  54  made of a thermosetting synthetic resin material. Thereby, the land  36  is stably fixed to the FPC  50 . In addition, a portion of the synthetic resin layer  54  covering the side face of the land  36  allows the piezoelectric body  45  and the FPC  50  to be physically firmly fixed to each other. Moreover, electrical insulation between the individual electrode  35  and the other wirings  53  can be improved. Like the land provided on the individual electrode  35 , the land provided on the surface electrode is also electrically bonded to a terminal of another wiring formed on the FPC  50 . 
     Here, an operation of the actuator unit  21  will be described. In the actuator unit  21 , only the piezoelectric layer  41  among the four piezoelectric layers  41  to  44  is polarized in a direction oriented from the individual electrode  35  toward the common electrode  34 . When the driver IC gives a predetermined potential to an individual electrode  35 , voltage is applied to an active region of the piezoelectric layer  41 , that is, a region of the piezoelectric layer  41  sandwiched between the individual electrode  35  given the predetermined potential and the common electrode  43  kept at the ground potential. As a result, an electric field in a thickness direction is generated in the region of the piezoelectric layer  41 , so that the active region of the piezoelectric layer  41  contracts in a direction perpendicular to a polarization direction by a transversal piezoelectric effect. The other piezoelectric layers  42  to  44  do not contract in this way, because the electric field is not applied thereto. Therefore, portions of the piezoelectric layers  41  to  44  opposed to the active region, as a whole, present unimorph deformation protruding toward the pressure chamber  10 . This reduces the volume of the pressure chamber  10  thus raising ink pressure, so that ink is ejected from the ink ejection port  8  shown in  FIG. 4 . Then, when the potential of the individual electrode  35  returns to the ground potential, the piezoelectric layers  41  to  44  restore their original shapes and the pressure chamber  10  restores its original volume. Ink is accordingly sucked from the sub manifold channel  5   a  into the individual ink passage. 
     In another driving mode, a predetermined potential is given to the individual electrode  35  beforehand. Upon every ejection request, the individual electrode  35  is once set at the ground potential and then given the predetermined potential again at a predetermined timing. In this mode, at a timing of setting the individual electrode  35  at the ground potential, the piezoelectric layers  41  to  44  return to their original state and the volume of the pressure chamber  10  becomes larger than in an initial state where a predetermined voltage is applied beforehand. Therefore, ink is sucked from the sub manifold channel  5   a  into the pressure chamber  10 . Then, at a timing of giving the predetermined potential to the individual electrode  35  again, portions of the piezoelectric layers  41  to  44  opposed to the active region deform protrudingly toward the pressure chamber  10 . The volume of the pressure chamber  10  accordingly changes to raise ink pressure, so that ink is ejected from the ink ejection port  8 . 
     Next, a method of manufacturing the head main body  3  will be described with reference to  FIGS. 7A to 7D .  FIGS. 7A to 7D  are sectional views showing step by step a method of manufacturing the head main body  13 . 
     To manufacture the head main body  13 , the above-described passage unit  4  is prepared in advance by putting the plates  22  to  30  in layers and bonding them to each other. Meanwhile, a conductive paste which is to be the common electrode  34  is printed in a pattern on a green sheet made of a ceramic material which is to be the piezoelectric layer  42 , while a conductive paste which is to be the individual electrodes  35  is printed in a pattern on a green sheet made of a ceramic material which is to be the piezoelectric layer  41 . Here, an Ag—Pd-base paste is used for the common electrode  34 , and an Au-base paste is used for the individual electrodes  35 . A thickness of the common electrode  34  is approximately 2 μm, and a thickness of the individual electrodes  35  is approximately 1 μm. Subsequently, the four piezoelectric layers  41  to  44  are positioned in layers to obtain a layered body which is then baked at a predetermined temperature, thereby forming the piezoelectric body  45  that includes the four piezoelectric layers  41  to  44  and supports the electrodes  34  and  35 . 
     Thereafter, as shown in  FIG. 7A , the land  36  made of a resin paste including a conductive material is formed on each individual electrode  35 , to be more specific, on a region of the individual electrode  35  not opposed to the pressure chamber  10  as described above, by means of a mask printing (land forming step). At this time, a whole of a lower face of the piezoelectric body  45  is supported on a support member  201 . The resin paste is for example a printing paste including ceramic particles and conductive particles. Each of the particles is formed of a spherical particle. Silicon dioxide, aluminum oxide, or the like is used for the ceramic particles. The conductive particle includes a vinyl or acrylic resin particle as a core material, on a surface of which a layer of a metal such as Au, Ni, Cu, or the like is formed. The resin paste is printed in a predetermined pattern and then baked at approximately 150 to 200 degrees C. Thereby, resin paste is cured to form the lands  36 . In this embodiment, the operation is performed at approximately 180 degrees C. 
     Next, as shown in  FIG. 7B , the piezoelectric actuator  21  is disposed on the passage unit  4  with a thermosetting adhesive therebetween in such a manner that the pressure chambers  10  and the individual electrodes  35  are opposed to each other. Under this condition, by use of a plate-like jig  60  capable of temperature control with a built-in heater, the lands  36  are pressed down while heating up to a curing temperature of the thermosetting adhesive or higher. As a result, the thermosetting adhesive is cured, and the piezoelectric actuator  21  is bonded to the passage unit  4  with the thermosetting adhesive (bonding step). 
     A recess  60   a  is formed on a lower face of the jig  60  used at this time. The recess  60   a  is in a plan view smaller than a contour of the land  36 , and a depth of the recess  60   a  is larger than a height of the land  36 . In addition, the recess  60   a  is in a plan view smaller than a contour of the terminal  53   a  and a contour of the through hole  52   a . To be specific, the recess  60   a  has a diameter of approximately 15 μm in a plan view. In the bonding step, the jig  60  is positioned so as to locate the recess  60   a  at a central portion of the land  36  in a plan view, and then the land  36  is pressed by the jig  60 . Pressing force is applied only to a portion of the land  36  not overlapping the recess  60   a  in a plan view, which means the peripheral portion  36   b  of the land  36 . The peripheral portion  36   b  is pressed by the jig  60  and thus reduced in height. Here, no matter how large the pressing force is, the height of the peripheral portion  36   b  is not reduced beyond a certain limit. On the other hand, the central portion surrounded by the peripheral portion  36   b  is not pressed by the jig  60  and therefore not reduced in height. As a result, the central portion of the land  36  becomes the protrusion  36   a  that protrudes upward more largely than the peripheral portion  36   b  does. 
     Next, as shown in  FIG. 7C , the FPC  50  is disposed above the piezoelectric actuator  21  in such a manner that the protrusion  36   a  and the through hole  52   a  overlap each other in a plan view. The synthetic resin layer  54 , which is not cured, is formed on the FPC  50  so as to cover the terminal  53   a  exposed from the covering layer  52  and therearound. 
     Then, as shown in  FIG. 7D , by use of an unillustrated plate-like jig capable of temperature control with a built-in heater, the land  36  of the piezoelectric actuator  21  is pressed by the FPC  50  which has been positioned in such a manner that the protrusion  36   a  and the through hole  52   a  overlap each other in a plan view, while heating up to a curing temperature of the synthetic resin layer  54  or higher. At this time, the synthetic resin layer  54  is once softened in a curing process. The protrusion  36   a  of the land  36  penetrates the synthetic resin layer  54  thus softened, to reach the terminal  53   a  thereby electrically bonding the land  36  to the terminal  53   a . Then, the synthetic resin layer  54  is cured, to physically fix the land  36  to the FPC  50  (connecting step). The head main body  13  is manufactured in the above-described manner. 
     In the above-described embodiment, since the land  36  is made of a resin paste including a conductive material, the land can be cured at a lower temperature than a land made of a metal paste can. This can suppress warping of the piezoelectric layers  41  to  44  in a curing process of the land  36 , and scattering of a metal material inside the piezoelectric layers  41  to  44  which deteriorates insulation resistance of the piezoelectric layers  41  to  44 . In addition, since the land  36  is made of a resin paste, manufacturing costs can be reduced as compared with when the land  36  is made of a metal material such as gold. 
     Besides, since the lands  36  are formed on the piezoelectric actuator  21  before the piezoelectric actuator  21  is bonded to the passage unit  4 , the lands  36  can be formed under a state where the whole of the lower face of the piezoelectric actuator is supported on the support member  201 . This makes it difficult that, when forming lands, cracking occurs in the piezoelectric body  45 . 
     Moreover, when bonding the piezoelectric actuator  21  to the passage unit  4 , the land  36  is pressed except its protrusion  36   a . Therefore, the protrusion  36   a  of the land  36  is not crushed due to a bonding press. Thus, the protrusion  36   a  of the land  36  is not reduced in height, so that a sufficient space is ensured between the piezoelectric body  45  and the FPC  50 . This can prevent ejection failure which may otherwise be caused by occurrence of contact between the FPC  50  and the piezoelectric body  45 . 
     Since the protrusions  36   a  are not pressed in the bonding step, it is likely that, after the bonding step, the height of the protrusion  36   a  differs from land to land. However, an upper face of the protrusion  36   a  of the land  36  is not flat even after the bonding step. When electrically bonding the land  36  to the terminal  53   a , the upper face of the protrusion  36   a  is pressed and easily deformed. Unevenness of heights of the lands  36  can thereby be absorbed, and the lands  36  and the terminal  53   a  are surely connected to each other. 
     In addition, when bonding the passage unit  4  and the piezoelectric actuator  21 , the plate-like jig  60  does not directly press the piezoelectric body  45 , but presses the piezoelectric body  45  with the lands  36  therebetween. This can prevent the jig  60  from getting too close, beyond a limit, to the piezoelectric body  45  during the bonding step. Therefore, even if a small foreign matter exists between the piezoelectric body  45  and the jig  60  or a small protrusion exists on a surface of the piezoelectric body  45 , no pressure is applied to the foreign matter or protrusion. Accordingly, occurrence of cracking or the like in the piezoelectric body  45  can be prevented. 
     The bonding step is performed under the state where the plate-like jig  60  is positioned with the recess  60   a  formed therein being opposed to a central portion of the land  36 . Therefore, it is easy to form the protrusion  36   a  on the land  36 . 
     The recess  60   a  formed in the jig  60  is smaller than the contour of the land  36  in a plan view. In the bonding step, the jig  60  is positioned in such a manner that the central portion is surrounded by the peripheral portion  36   b . This gives the land  36  a highly reliable, stable shape having its protrusion  36   a  surrounded by a portion shorter than the protrusion  36   a.    
     Since the recess  60   a  is smaller than the contour of the terminal  53   a  in a plan view, the protrusion  36   a  is not made larger than the contour of the terminal  53   a . Therefore, the protrusion  36   a  can be formed small, and it is easy for the protrusion  36   a  to come into contact with the terminal  53   a  exposed at the bottom of the through hole  52   a . In addition, even when the wiring  53  is not covered with the covering layer  52 , the protrusion  36   a  hardly comes into contact with another terminal adjacent to the terminal  53   a  that is intended for this protrusion  36   a.    
     The depth of the recess  60   a  is larger than the height of the land  36 . Accordingly, even when in the bonding step the jig  60  gets close to the piezoelectric actuator  21  to the maximum, the protrusion  36   a  is not lowered by being pressed by the jig  60 . It is therefore certain that a sufficient space is ensured between the piezoelectric body  45  and the FPC  50 . 
     The synthetic resin layer  54  is cured at a relatively low temperature of approximately 150 degrees C. Therefore, a drawback caused by heat, such as warping of the piezoelectric body  45 , does not easily occur in the connecting step. Moreover, since the uncured synthetic resin is cured by heating at this time, mechanical bond strength between the land  36  and the FPC  50  is improved. 
     Further, since the jig  60  having the recess  60   a  formed therein is used, it is easy to press only the peripheral portion  36   b  of the land  36  when bonding the passage unit  4  and the piezoelectric actuator  21 . 
     Next, various modifications made to the above-described embodiment will be described. In the following, the same constructions as in the above-described embodiment will be denoted by the same reference numerals, and descriptions thereof will suitably be omitted. 
     [First Modification] 
     In a first modification, as shown in  FIG. 8A , an uncured thermosetting synthetic resin layer  74  instead of the covering layer  52  is formed on a lower face of the wiring  53 . In the connecting step, as shown in  FIG. 8B , by use of an unillustrated plate-like jig capable of temperature control with a built-in heater, the land  36  of the piezoelectric actuator  21  is pressed by the FPC  70  which has been positioned in such a manner that the protrusion  36   a  and the terminal  53   a  overlap each other in a plan view, while heating up to a curing temperature of the synthetic resin layer  74  or higher. At this time, the synthetic resin layer  74  is once softened in a curing process. The protrusion  36   a  of the land  36  penetrates the synthetic resin layer  74  thus softened, to reach the terminal  53   a  thereby electrically bonding the land  36  to the terminal  53   a . Then, the synthetic resin layer  74  is cured, to physically fix the land  36  to the FPC  70 . Further, a whole of the lower face of the wiring  53  is covered with the cured synthetic resin layer  74 . Consequently, the wiring  53  can surely be kept insulated from its neighboring wiring  53 . 
     [Second Modification] 
     In another modification, as shown in  FIG. 9A , an uncured synthetic resin layer  81  made of a thermosetting synthetic resin material is formed on an upper face of the land  36  after the bonding step, to cover the land  36  with the synthetic resin layer  81  (resin layer forming step). 
     Then in the connecting step, as shown in  FIG. 9B , by use of an unillustrated plate-like jig capable of temperature control with a built-in heater, the land  36  is pressed by the FPC  50  which has been positioned in such a manner that the protrusion  36   a  and the terminal  53   a  overlap each other in a plan view, while heating up to a curing temperature of the synthetic resin layer  81  or higher. At this time, the synthetic resin layer  81  is once softened in a curing process. The protrusion  36   a  of the land  36  penetrates the synthetic resin layer  81  thus softened, to reach the terminal  53   a  thereby electrically bonding the land  36  to the terminal  53   a . Then, the synthetic resin layer  81  is cured, to physically fix the land  36  to the FPC  50 . 
     The synthetic resin layer  81  is cured at a relatively low temperature of approximately 150 degrees C. Therefore, a drawback caused by heat, such as warping of the piezoelectric body  45 , does not easily occur in the connecting step. Moreover, since the uncured synthetic resin is cured by heating at this time, mechanical bond strength between the land  36  and the FPC  50  is improved. 
     [Third Modification] 
     In another modification, an FPC  85  as shown in  FIG. 10A  is adopted. In the FPC  85 , the terminal  53   a  is covered with a bump  86  made of a conductive material. The bump  86  fills up the through hole  52   a  and further spreads to cover a part of a lower face of the covering layer  52 . In addition, a lower face of the bump  86  is covered with a solder layer  87 . A softening temperature of the bump  86  is higher than a softening temperature of the solder layer  87 . 
     In the connecting step in this case, as shown in  FIG. 10B , by use of an unillustrated plate-like jig capable of temperature control with a built-in heater, the land  36  is pressed by the FPC  85  which has been positioned in such a manner that the protrusion  36   a  and the terminal  53   a  overlap each other in a plan view, while heating up to a temperature that is equal to or higher than a softening temperature of the solder layer  87  and lower than a softening temperature of the bump  86 . The solder layer  87  is thereby melted, and the protrusion  36   a  of the land  36  enters the solder layer  87 . By stopping heating, the solder layer  87  is cured, and the protrusion  36   a  and the solder layer  87  are electrically bonded to each other. Thus, the land  36  is electrically connected to the terminal  53   a.    
     It may also be possible that an upper end of the protrusion  36   a  penetrates the solder layer  87  and reaches the bump  86 . Besides, an uncured synthetic resin layer may be formed so as to cover the land  36 . This synthetic resin layer is cured by the heating in the bonding. Thus, the cured synthetic resin layer directly bonds the piezoelectric body  45  to the FPC  85  while preventing excessive spreading of the melted solder. That is, the spreading of the solder can be restricted to the vicinity of the land  36 . 
     [Fourth Modification] 
     In another modification, in the bonding step, a jig  90  is disposed as shown in  FIG. 11 , in such a manner that a part of a recess  90   a  formed in the jig  90 , which means a left end portion of the recess  90   a  in  FIG. 11 , overlaps a land  91  in a plan view while a remaining part of the recess  90   a , which means a right end portion of the recess  90   a  in  FIG. 11 , does not overlap the land  91  in a plan view. In this condition, the land  91  is pressed by the jig  90 . Here, a diameter of the recess  90   a  is smaller than a diameter of the land  91 , and a depth of the recess  90   a  is smaller than a height of the land  91 . 
     In this case, after the bonding step, a protrusion  91   a  appears at a right end portion of the land  91 , while a remaining portion of the land  91  is pressed by the jig  90  and therefore flattened. The land  91  may be electrically connected to the terminal  53   a  by, in the connecting step, making the protrusion  91   a  and the terminal  53   a  overlap each other in a plan view. 
     [Fifth Modification] 
     In another modification, as shown in  FIG. 12 , a jig  95  having a through hole  95   a  formed therein is used. A diameter of the through hole  95   a  is smaller than a diameter of the land  36 . In the bonding step, the jig  95  is disposed so as to make the through hole  95   a  overlap the central portion of the land  36  in a plan view, and then the jig  95  presses the land  36  while heating. Thereby, the passage unit  4  and the piezoelectric actuator  21  are bonded to each other. In this case as well, a portion of the land  36  overlapping the through hole  95   a  is not pressed, so that the protrusion  36   a  is formed on the land  36  in the bonding step. At this time, even if the protrusion  36   a  passes through the through hole  95   a  and protrudes out from an opposite side of the through hole  95   a , the protrusion  36   a  can be kept at a desired height all the easier regardless of a thickness of the jig  95 , because nothing restricts the protrusion  36   a.    
     [Other Modifications] 
     A piezoelectric body may include one to three piezoelectric layers, or alternatively may include five or more piezoelectric layers. However, in consideration of producing unimorph deformation, it is preferable that the piezoelectric body includes one or more active layers and one or more inactive layers. 
     In the above-described embodiment, the land is provided on the individual electrode that is formed on the surface of the piezoelectric body. However, the land may not necessarily be provided on the individual electrode but on any electrode, as long as the electrode is formed on the surface of the piezoelectric body. 
     In a case where the thermosetting adhesive is not interposed between the passage unit and the piezoelectric actuator, heating is not required in the bonding step. 
     While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims.