Patent Publication Number: US-8985749-B2

Title: Liquid ejection head and liquid ejection apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to liquid ejection heads and liquid ejection apparatuses, and more specifically to ink jet recording heads and ink jet recording apparatuses that eject ink as a liquid. 
     2. Related Art 
     Ink jet recording heads that eject ink droplets from nozzles by using pressure, for example, generated by deformation of piezoelectric elements are known as a typical example of liquid ejection head. Specifically, as described in JP-A-2004-74740, an ink jet recording head includes a flow path unit in which pressure generating chambers that communicate with nozzles are formed and having a flow path forming plate and a vibration plate disposed on one face of the flow path forming plate, piezoelectric elements (piezoelectric transducers) secured to the fixation plate corresponding to the respective pressure generating chambers, and a case head (structure) having a housing chamber in which the fixation plate is mounted. 
     In such an ink jet recording head, the fixation plate and the case head are bonded together with an adhesive such as epoxy resin adhesive after the respective piezoelectric elements are positioned so as to oppose the respective pressure generating chambers. 
     However, it takes a long time for epoxy resin adhesive to cure and the positioning needs to be retained by using a jig and the like. Since the jig is in use for a long period of time for holding the ink jet recording head, it leads to decrease of manufacturing efficiency. If a number of jigs are used to improve the efficiency, it leads to increase of manufacturing cost. 
     Further, if a jig is not used, the piezoelectric elements are displaced from the respective pressure generating chambers before the epoxy resin adhesive cures. That is, the precision in positioning the piezoelectric elements relative to the pressure generating chambers decreases, thereby causing a problem that desired ink ejection properties cannot be achieved. 
     Such a problem exists not only in ink jet recording heads but only in liquid ejection heads that eject a liquid other than ink. 
     SUMMARY 
     An advantage of some aspects of the invention is that liquid ejection heads and liquid ejection apparatuses that can be manufactured in a simplified process and have improved liquid ejection characteristics by preventing displacement between piezoelectric elements and pressure generating chambers are provided. 
     According to an aspect of the invention, a liquid ejection head includes a flow path unit having a plurality of pressure generating chambers that communicate with nozzles through which liquid is ejected; a case head that is mounted on the flow path unit; and a piezoelectric element unit having a fixation member and piezoelectric elements, one face of the fixation member being adhered to the case head by using a first adhesive and a second adhesive, and the piezoelectric elements being bonded to the fixation member and also attached to areas that oppose the pressure generating chambers of the flow path unit, wherein the second adhesive has curing time shorter than that of the first adhesive and is applied on a first area on the one face of the fixation member, the first adhesive has adhesion strength higher than that of the second adhesive and is applied on a second area on the one face of the fixation member, and the second area is subject to a reaction force larger than the first area. With this configuration, the first adhesive having high adhesion strength is applied on the area which is subject to a reaction force of the piezoelectric elements. Accordingly, it is possible to prevent the fixation member from being removed or displaced from the case head, even when the reaction force of the piezoelectric elements acts on the fixation member. Therefore, it is possible to prevent the piezoelectric elements from being displaced from the area that opposes the pressure generating chambers, thereby providing the liquid ejection head having improved liquid ejection characteristics. Further, when the piezoelectric element unit is positioned on the case head and bonded by using the first adhesive and the second adhesive, the second adhesive instantly cures after the positioning. Accordingly, the positioning of the piezoelectric element unit can be retained until the first adhesive cures. Therefore, it is possible to prevent the piezoelectric elements from being displaced from the area that opposes the pressure generating chambers during the time period from the positioning of the piezoelectric element unit to curing of the first adhesive, thereby providing the liquid ejection head having improved liquid ejection characteristics. 
     It is preferable that the piezoelectric elements are provided corresponding to each of the plurality of pressure generating chambers that are arranged in one direction, the first adhesive is applied on a first adhesive surface on the one face of the fixation member that overlaps the piezoelectric elements in the one direction, and the second adhesive is applied on a second adhesive surface that is provided on the outer side of the first adhesive surface. With this configuration, the first adhesive surface which is subject to the reaction force of the piezoelectric elements and the second adhesive surface which is not subject to the reaction force of the piezoelectric elements are adhered to the case head by using the first adhesive and the second adhesive, respectively. 
     Further, it is preferable that the piezoelectric element unit has a non-deforming section that does not deform disposed on the outer side of the piezoelectric elements in the one direction, the second adhesive surface has an area that overlaps the non-deforming section in the one direction on the one face of the fixation member, and the second adhesive is applied on the entire second adhesive surface. With this configuration, the first adhesive having high adhesion strength is applied on the entire first adhesive surface which is subject to the reaction force. Accordingly, displacement of the fixation member due to the reaction force can be more reliably prevented. Moreover, in the adhesive surfaces of the fixation member to the case head, the second adhesive surface for temporary fixation by the second adhesive can be maximized. Accordingly, temporary fixation by the second adhesive can be enhanced. 
     Further, it is preferable that the first adhesive is a thermosetting adhesive, and the second adhesive is an ultraviolet curable adhesive or an instant adhesive. With this configuration, it is possible to more strongly adhere the fixation member and the case head on the first adhesive surface, and more quickly adhere the fixation member and the case head on the second adhesive surface. 
     According to another aspect of the invention, a liquid ejection apparatus includes the liquid ejection head according to the above aspect. With this configuration, manufacturing process can be simplified, and displacement between the piezoelectric elements and the pressure generating chambers can be prevented, thereby providing the liquid ejection apparatus having improved liquid ejection characteristics. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a sectional view of an ink jet recording head according to a first embodiment. 
         FIGS. 2A and 2B  are sectional views of the ink jet recording head according to the first embodiment. 
         FIG. 3A  is a front view of a piezoelectric element unit according to the first embodiment. 
         FIG. 3B  is a sectional view taken along the line IIIB-IIIB of  FIG. 3A . 
         FIG. 4  is a bottom view of the piezoelectric element unit according to the first embodiment. 
         FIG. 5  is a sectional view taken along the line V-V of  FIG. 2A . 
         FIG. 6  is an enlarged view of an essential part of a section taken along the line VI-VI of  FIG. 2B . 
         FIG. 7  is a sectional view of an ink jet recording head according to other embodiment. 
         FIG. 8  is a schematic view of one example of an ink jet recording apparatus according to an embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
     The invention will be described in detail with reference to an embodiment.  FIG. 1  is a sectional view in short direction of a pressure generating chamber of an ink jet recording head as an example of liquid ejection head according to a first embodiment of the invention.  FIG. 2A  is a sectional view taken along the line IIA-IIA of  FIG. 1 , and  FIG. 2B  is a sectional view taken along the line IIB-IIB of  FIG. 2A . 
     As shown in the figure, an ink jet recording head  10  includes a flow path unit  16  that has a flow path forming substrate  12  having a plurality of pressure generating chambers  11 , a nozzle plate  14  in which a plurality of nozzles  13  that communicate with the respective pressure generating chambers  11  are formed by drilling, and a vibration plate  15  disposed on the flow path forming substrate  12  opposite to the nozzle plate  14 . The ink jet recording head  10  further includes a piezoelectric element unit  18  that has piezoelectric elements  17  disposed in areas corresponding to the respective pressure generating chambers  11  on the vibration plate  15 , and a case head  20  that is secured to the vibration plate  15  and has a containing section  51  for housing the piezoelectric element unit  18 . 
     The plurality of pressure generating chambers  11  which are separated by partitions  11   a  are arranged in the width direction on a surface layer of one face of the flow path forming substrate  12 . A reservoir  22  that penetrates the flow path forming substrate  12  in the thickness direction is formed in the outside area of the array of pressure generating chambers  11  such that ink is supplied through an ink introduction path  21  which is a liquid introduction path of the case head  20 . The reservoir  22  communicates with the respective pressure generating chambers  11  via ink supply paths  23 . Ink is supplied to the respective pressure generating chambers  11  via the ink introduction path  21 , the reservoir  22  and ink supply paths  23 . Further, nozzle communication holes  24  that penetrate the flow path forming substrate  12  are formed at the end of the pressure generating chambers  11  opposite to the reservoir  22 . That is, in this embodiment, the pressure generating chambers  11 , the reservoir  22 , the ink supply paths  23  and the nozzle communication holes  24  are formed in the flow path forming substrate  12  as a liquid flow path. In this embodiment, the flow path forming substrate  12  is formed of a silicon single crystal substrate. The pressure generating chambers  11  and the like are formed on the flow path forming substrate  12  by etching the flow path forming substrate  12 . 
     The nozzle plate  14  in which the nozzles  13  are formed by drilling is bonded on one face of the flow path forming substrate  12  such that the respective nozzles  13  communicate with the respective pressure generating chambers  11  via nozzle communication holes  24  formed in the flow path forming substrate  12 . 
     The vibration plate  15  is bonded on the other face of the flow path forming substrate  12 , that is, the surface having openings of the pressure generating chambers  11  such that the respective pressure generating chambers  11  are sealed by the vibration plate  15 . 
     The vibration plate  15  is a composite plate formed of an elastic film  25  and a support plate  26 , and is bonded to the flow path forming substrate  12  on the side of the elastic film  25 . For example, the elastic film  25  is made of an elastic member such as a resin film, while the support plate  26  is made of a material such as metal. Further, islands  27  are formed in areas of the vibration plate  15  that oppose the respective pressure generating chambers  11 , and the distal end of each piezoelectric element  17  abuts against the island  27 . That is, thin-walled portions  28  having a thickness that is thinner than other area are formed in areas of the vibration plate  15  that oppose the peripheral areas of the respective pressure generating chambers  11  such that each island  27  is surrounded by the thin-walled portion  28 . 
     Further, a compliance section  29  is formed in an area of the vibration plate  15  that opposes the reservoir  22 . The compliance section  29  is formed by etching the support plate  26  in a similar manner to the thin-walled portion  28  and substantially made of the elastic film  25  only. In the compliance section  29 , when a pressure change occurs in the reservoir  22 , the elastic film  25  of the compliance section  29  deforms to absorb the pressure change so as to keep a constant pressure in the reservoir  22 . 
     The piezoelectric element unit  18  will be described with reference to  FIGS. 3A ,  3 B and  4 .  FIG. 3A  is a front view of the piezoelectric element unit  18 ,  FIG. 3B  is a sectional view taken along the line IIIB-IIIB of  FIG. 3A , and  FIG. 4  is a bottom view of the piezoelectric element unit  18 . In  FIG. 4 , an external electrode  90  (individual external electrodes  92  and common external electrodes  93 ) are not shown. 
     The piezoelectric element unit  18  includes a piezoelectric element forming member  34  and a fixation member  35 . In the piezoelectric element forming member  34 , a plurality of piezoelectric elements  17  are arranged in the width direction. The distal end (one end) of the piezoelectric element forming member  34  serves as a free end, while the proximal end (the other end) of the piezoelectric element forming member  34  is bonded to the fixation member  35  as a fixed end. 
     The piezoelectric element forming member  34  includes piezoelectric materials  31 , internal electrodes that form two poles of the piezoelectric elements  17 , that is, individual internal electrodes  32  that form internal electrodes electrically independent from the adjacent piezoelectric elements  17 , and common internal electrodes  33  that form common electrodes common to the adjacent piezoelectric elements  17 , which are sequentially stacked. 
     In the piezoelectric element forming member  34 , the piezoelectric elements  17  separated into a comb-like shape, for example, by a wire saw are arranged in an array so as to oppose the respective pressure generating chambers  11 . Positioning sections  19  each having a width greater than that of each piezoelectric element  17  are formed on both outer sides of the array of the piezoelectric elements  17 . The positioning sections  19  are formed such that voltage is not applied thereto and do not deform. The positioning sections  19  are provided for positioning the piezoelectric element unit  18  with high precision when the piezoelectric element unit  18  is assembled to the ink jet recording head  10 . 
     The external electrode  90  that is connected to the individual internal electrodes  32  and the common internal electrodes  33  is formed on the outer surface of the piezoelectric element forming member  34 . Further, a non-electrode forming section  91  is formed on the portion of piezoelectric element forming member  34  in an area other than the external electrode  90 , which at least corresponds to the proximal end of the piezoelectric elements  17 . 
     The external electrode  90  includes the individual external electrodes  92  formed by providing the non-electrode forming section  91  and separating the piezoelectric elements  17  into a comb-like shape and electrically independent from the adjacent piezoelectric elements  17 , and common external electrodes  93  common to the adjacent piezoelectric elements  17 . 
     Specifically, the external electrode  90  is divided into a portion that opposes the piezoelectric elements  17  and a portion that opposes the positioning sections  19 . The portion of the external electrode  90  that opposes the piezoelectric elements  17  is electrically connected to the individual internal electrodes  32  that form individual electrodes of the piezoelectric elements  17  at the distal end of the piezoelectric element forming member  34 , thereby forming the individual external electrodes  92 . On the other hand, the portion of the external electrode  90  on the positioning sections  19  that is formed on both outer sides of the array of the piezoelectric elements  17  is connected to the common internal electrodes  33  that form common electrodes of the piezoelectric elements  17  at the proximal end of the piezoelectric element forming member  34 , thereby forming the common external electrodes  93 . 
     The fixation member  35  is made of a material such as a resin. The above described piezoelectric element forming member  34  (the piezoelectric elements  17 ) is bonded to the fixation member  35 , and the fixation member  35  is adhered to the case head  20 . That is, an adhesive surface  35   a  which is one face of the fixation member  35  is adhered to the case head  20  by a first adhesive  71  and a second adhesive  72  which will be described later. The piezoelectric element forming member  34  (the piezoelectric elements  17 ) is bonded on the other face of the fixation member  35  which intersects with the adhesive surface  35   a  (hereinafter, referred to as a piezoelectric element attachment surface  35   b ). 
     As shown in  FIG. 4 , the piezoelectric elements  17  are arranged in one direction (hereinafter, referred to as arrangement direction X), and the positioning sections  19  (non-deforming sections) that do not deform by application of voltage are provided on both sides of the piezoelectric elements  17  in the arrangement direction X. 
     In the piezoelectric element unit  18 , when the piezoelectric elements  17  deform, a reaction force is applied from the fixation end of the piezoelectric elements  17  to the piezoelectric element attachment surface  35   b  of the fixation member  35 . More specifically, the reaction force is applied to the area of the piezoelectric element attachment surface  35   b  on which the piezoelectric elements  17  are bonded (hereinafter, referred to as first area  81 ), while the reaction force is not applied to the area of the piezoelectric element attachment surface  35   b  on which the positioning sections  19  are bonded (hereinafter, referred to as second area  82 ). 
     The reaction force applied to the first area  81  has an effect to the adhesive surface  35   a . The area of the adhesive surface  35   a  that overlaps the piezoelectric elements  17  in the arrangement direction X is defines as a first adhesive surface  61 . That is, the size (width) and position of the area on the piezoelectric elements  17  in the arrangement direction X are substantially same as the size (width) and position of the area on the first adhesive surface  61  in the arrangement direction X. 
     The reaction force of the piezoelectric elements  17  applied to the first area  81  acts on the first adhesive surface  61 . In this embodiment, the adhesive surface  35   a  is vertical to the piezoelectric element attachment surface  35   b  as shown in  FIG. 3B . In this case, when the reaction force of the piezoelectric elements  17  is applied to the first area  81  of the fixation member  35 , it acts on the first adhesive surface  61  as a force in the parallel direction, that is, a shear force. Accordingly, as will be described later in detail, the reaction force of the piezoelectric elements  17  acts on the first adhesive surface  61  to displace the fixation member  35  adhered to the case head  20 . Although the adhesive surface  35   a  is described as being vertical to the piezoelectric element attachment surface  35   b , it is not limited thereto since the reaction force of the piezoelectric elements  17  acts on the first adhesive surface  61  of the fixation member  35  as a shear force in the case where the adhesive surface  35   a  is not vertical to the piezoelectric element attachment surface  35   b.    
     On the other hand, the reaction force of the piezoelectric elements  17  is not applied to the second area  82 , and therefore does not act as a force to shear the second adhesive surface  62 . Accordingly, as will be described later in detail, the reaction force of the piezoelectric elements  17  does not act on the second adhesive surface  62  to displace the fixation member  35  adhered to the case head  20 . 
     With further reference to  FIGS. 1 ,  2 A, and  2 B the piezoelectric element unit  18  is mounted with the distal end of the piezoelectric elements  17  abutting against the islands  27  of the vibration plate  15 . Moreover, the case head  20  is secured to the vibration plate  15 , and the piezoelectric element unit  18  is secured to the case head  20 . 
     The containing section  51  is formed in the case head  20  in the area that opposes the islands  27  so as to penetrate in the thickness direction. The containing section  51  houses the piezoelectric element unit  18 . Further, the containing section  51  of the case head  20  has a stepped portion  38  formed therein such that the side of the vibration plate  15  is narrower. The fixation member  35  is adhered on the inner surface of the case head  20  at the stepped portion  38  by using a first adhesive  71  and a second adhesive  72 . The adhesion between the fixation member  35  and the case head  20  by using the first adhesive  71  and second adhesive  72  will be described later in detail. 
     The case head  20  is made of, for example, a resin material. The inner surface of the containing section  51  of the case head  20  serves as an alignment surface  50  against which at least a portion of the side surface of the piezoelectric element unit  18  abuts. The alignment surface  50  is an inner surface of the containing section  51  at one end of the arrangement direction of the pressure generating chambers  11  such that the positioning section  19  at one end of the arrangement direction of the piezoelectric elements  17  abuts against the alignment surface  50 . The plurality of pressure generating chambers  11  are arranged in the short direction (width direction), and the plurality of piezoelectric elements  17  are arranged in the short direction (width direction) of their end face, corresponding to the plurality of pressure generating chambers  11 . That is, the arrangement direction of the piezoelectric elements  17  is the short direction of the end face that is attached to the islands  27 , such that the positioning of the short direction of the piezoelectric elements  17  and the short direction of the islands  27  is achieved by abutting the positioning section  19  against the alignment surface  50  of the case head  20 . 
     Both the width of the island  27  in the short direction and the width of the piezoelectric elements  17  in the short direction are on the order of tens of micrometers and both are formed with substantially the same width. Accordingly, if the high-precise positioning of the short direction of the piezoelectric elements  17  and the short direction of the islands  27  fails, the displacement of the piezoelectric elements  17  is not transmitted to the vibration plate  15  via the islands  27 , leading to deterioration in ink ejection characteristics. 
     In this embodiment, since the positioning is performed by abutting the alignment surface  50  of the case head  20  and the positioning sections  19 , the piezoelectric elements  17  and the islands  27  are mounted with being precisely aligned relative to each other in the short direction, thereby achieving excellent ink ejection characteristics. 
     The piezoelectric element unit  18  mounted on the case head  20  is connected to a flexible wiring substrate  37  that supplies signals for driving the respective piezoelectric elements  17 . The flexible wiring substrate  37  is electrically connected to the individual external electrodes  92  and the common external electrodes  93  of the piezoelectric elements  17 . 
     A wiring substrate  41  is mounted on the case head  20  with a plurality of conductive pads  40  for connecting with wirings  36  of the flexible wiring substrate  37  disposed thereon, and the wiring substrate  41  substantially covers the containing section  51  of the case head  20 . The wiring substrate  41  has a slit-shaped opening  42  in the area that opposes the containing section  51  of the case head  20 , and the flexible wiring substrate  37  is drawn out through the opening  42  of the wiring substrate  41  to the outside of the containing section  51 . 
     In this embodiment, the flexible wiring substrate  37  that forms the piezoelectric element unit  18  is made of, for example, a chip on film (COF) on which a driving IC (not shown in the figure) for driving the piezoelectric elements  17  is mounted. The proximal ends of the wirings  36  of the flexible wiring substrate  37  are connected to the individual external electrodes  92  and the common external electrodes  93  that form the piezoelectric elements  17 , for example, by using solder, anisotropic conductive material or the like. On the other hand, the distal ends of the wirings  36  are connected to the respective conductive pads  40  of the wiring substrate  41 . Specifically, the wirings  36  are connected to the respective conductive pads  40  of the wiring substrate  41  with the distal end of the flexible wiring substrate  37  that is drawn out through the opening  42  of the wiring substrate  41  to the outside of the containing section  51  is folded along the surface of the wiring substrate  41 . 
     In the ink jet recording head  10 , during ejection of ink droplets, the piezoelectric elements  17  and the vibration plate  15  deform so as to change the volume of the respective pressure generating chambers  11 , thereby ejecting ink droplets from the specified nozzles  13 . Specifically, when ink is supplied from the ink cartridge which is not shown in the figure to the reservoir  22 , ink is distributed to the respective pressure generating chambers  11  via the ink supply paths  23 . In practice, the piezoelectric elements  17  contract by applying voltage to the piezoelectric elements  17 . This causes the vibration plate  15  to deform with the piezoelectric elements  17  so as to expand the volume of the pressure generating chambers  11 , thereby drawing ink into the pressure generating chambers  11 . When ink fills the pressure generating chambers  11  up to the nozzles  13 , the voltage applied to the piezoelectric elements  17  is released in response to the recording signals supplied via the wiring substrate  41 . Accordingly, as the piezoelectric elements  17  expand back to the initial state, the vibration plate  15  also deforms back to the initial state. As a result, the volume of the pressure generating chambers  11  contract, thereby increasing the pressure inside the pressure generating chambers  11  and ejecting ink droplets from nozzles  13 . 
     The adhesion between the piezoelectric element unit  18  and the case head  20  will be described in detail with reference to  FIGS. 5 and 6 .  FIG. 5  is a sectional view taken along the line V-V of  FIG. 2A , and  FIG. 6  is an enlarged view of an essential part of a section taken along the line VI-VI of  FIG. 2B . 
     As shown in the figures, the fixation member  35  is adhered on the surface of the stepped portion  38  of the case head  20  by using the first adhesive  71  and the second adhesive  72 . More specifically, the first adhesive surface  61  of the adhesive surface  35   a  of the fixation member  35  and the stepped portion  38  are adhered by the first adhesive  71 , while the second adhesive surface  62  of the adhesive surface  35   a  of the fixation member  35  and the stepped portion  38  are adhered by the second adhesive  72 . In this embodiment, the first adhesive  71  is applied on the entire first adhesive surface  61  and the second adhesive  72  is applied on the entire second adhesive surface  62 . 
     The first adhesive  71  has adhesion strength higher than that of the second adhesive  72 . For example, the first adhesive  71  may be thermosetting adhesive such as an epoxy adhesive. 
     The second adhesive  72  has curing time shorter than that of the first adhesive  71 . For example, ultraviolet curable adhesive or cyanoacrylate adhesive (instant adhesive) may be used. 
     As described above, the first adhesive surface  61  on which the first adhesive  71  is applied is the area on which the reaction force of the piezoelectric elements  17  acts. That is, the reaction force of the piezoelectric elements  17  acts on the first adhesive surface  61  to displace the fixation member  35  from the case head  20  (stepped portion  38 ). Since the first adhesive  71  having high adhesion strength is applied on the first adhesive surface  61 , it is possible to resist the reaction force. That is, it is possible to prevent the fixation member  35  from being displaced from the case head  20 . 
     On the other hand, as described above, the second adhesive surface  62  on which the second adhesive  72  is applied is the area on which the reaction force of the piezoelectric elements  17  does not act. Therefore, an adhesive having high adhesion strength is not necessary on the second adhesive surface  62 , and the second adhesive  72  having a short curing time may be used. Accordingly, it is possible to perform positioning of the piezoelectric element unit  18  on the case head  20 , temporarily fix the piezoelectric element unit  18  by using the second adhesive  72  applied on the second adhesive surface  62 , and retain the positioning of the piezoelectric element unit  18  until the first adhesive  71  cures. 
     As described above, in the ink jet recording head  10  according to the invention, the first adhesive  71  and the second adhesive  72  are used for the first adhesive surface  61  on which the reaction force of the piezoelectric elements  17  acts and the second adhesive surface  62  on which the reaction force of the piezoelectric elements  17  does not act, respectively. This makes it possible to prevent the fixation member  35  from being removed or displaced from the case head  20 , even when the reaction force due to the deformation of the piezoelectric elements  17  during ink ejection acts on the fixation member  35 . As a result, it is possible to prevent the piezoelectric elements  17  from being displaced from the area that opposes the pressure generating chambers  11  (the islands  27 ), thereby providing the ink jet recording head  10  having improved ink ejection characteristics. 
     When the piezoelectric element unit  18  is positioned on the case head  20  and bonded on the first adhesive surface  61  and the second adhesive surface  62  by using the first adhesive  71  and the second adhesive  72 , respectively, there is a risk that the piezoelectric element unit  18  may be displaced from the case head  20  due to contraction of the first adhesive  71 . In this embodiment, since the second adhesive  72  instantly cures after the positioning of the piezoelectric element unit  18 , the positioning of the piezoelectric element unit  18  can be retained until the first adhesive  71  cures. Therefore, it is possible to prevent the piezoelectric elements  17  from being displaced from the area that opposes the pressure generating chambers  11  (the islands  27 ) during the time period from the positioning of the piezoelectric element unit  18  to curing of the first adhesive  71 , thereby providing the ink jet recording head  10  having improved ink ejection characteristics. 
     Moreover, since the piezoelectric element unit  18  and the case head  20  are temporarily fixed by the second adhesive  72 , they do not need to be held by a jig or the like until the first adhesive  71  cures. That is, the piezoelectric element unit  18  and the case head  20  can be removed from the jig after the temporary fixation. Accordingly, the jig is not in use for a long period of time until the first adhesive  71  cures and can be used for manufacturing of other ink jet recording head  10 . This eliminates the needs of a number of jigs, thereby decreasing the manufacturing cost. 
     Further, in this embodiment, the first adhesive  71  is applied on the entire first adhesive surface  61 . That is, the first adhesive  71  having high adhesion strength is applied on all the area on which the reaction force of the piezoelectric elements  17  acts. Accordingly, displacement of the fixation member  35  due to the reaction force of the piezoelectric elements  17  can be more reliably prevented. In addition, the second adhesive  72  is applied on the entire second adhesive surface  62 . That is, the area for temporary fixation by the second adhesive  72  can be maximized in the adhesive surface  35   a . Accordingly, temporary fixation by the second adhesive  72  can be enhanced. 
     It should be noted that the first adhesive  71  is not necessarily applied on the entire first adhesive surface  61 . For example, the first adhesive  71  may be applied on a portion of the first adhesive surface  61  as appropriate to the extent that the fixation member  35  is not displaced or removed from the case head  20  due to the reaction force of the piezoelectric elements  17  and the weight of the piezoelectric element unit  18 . Likewise, the second adhesive  72  is not necessarily applied on the entire second adhesive surface  62 . For example, the second adhesive  72  may be applied on a portion of the second adhesive surface  62  as appropriate to the extent that the positioning of the piezoelectric element unit  18  on the case head  20  can be retained. 
     Further, in the above embodiment, the second adhesive surface  62  is defined to include the portion of the adhesive surface  35   a  that overlaps the positioning sections  19  which is a non-deforming section in the arrangement direction X, however the second adhesive surface  62  is not limited thereto. For example, the portion of the adhesive surface  35   a  that overlaps the piezoelectric element forming member  34  (piezoelectric elements and the positioning sections  19 ) in the arrangement direction X may be defined as the first adhesive surface  61 , and the remaining area may be defined as the second adhesive surface  62 . 
     Other Embodiments 
     Although the embodiment of the invention has been described above, the essential configuration of the invention is not limited thereto.  FIG. 7  is a sectional view of an ink jet recording head  10  according to other embodiment. In the case where an ultraviolet curable adhesive is used as the second adhesive  72 , an opening  95  that communicates with the containing section  51  may be formed in the case head  20  as shown in the figure. The ultraviolet light is irradiated to the adhesive surface  35   a  through the opening  95 . 
     In manufacturing of the ink jet recording head  10 , the first adhesive  71  such as an epoxy adhesive and the second adhesive  72  which is an ultraviolet curable adhesive are applied on the adhesive surface  35   a , and then, the piezoelectric elements  17  are positioned so that the distal ends of the piezoelectric elements  17  are attached on the islands  27 . Then, the ultraviolet light is irradiated to the adhesive surface  35   a  through the opening  95  so as to cure the second adhesive  72 . As a result, temporary fixation by the second adhesive  72  can be performed after positioning of the piezoelectric element unit  18  is reliably performed. The opening  95  may be sealed after the second adhesive  72  cures. 
     Further, although the positioning sections  19  in the piezoelectric element unit  18  are disposed on both outer sides of the array of the piezoelectric elements  17  in the above embodiment, the positioning section  19  is not necessarily disposed in the piezoelectric element unit  18 . In such a case, positioning of the piezoelectric element unit  18  can be performed by using other technique, for example, by aligning the optical images of the distal end of the piezoelectric elements  17  and the islands  27 . 
     The ink jet recording head described in the above embodiments is mounted in the ink jet recording apparatus and forms part of the recording head unit that is provided with ink flow paths that communicate with the ink cartridge and the like.  FIG. 8  is a schematic view of one example of the ink jet recording apparatus. 
     The ink jet recording apparatus  1  includes the ink jet recording head  10 . The ink jet recording head  10  and the ink cartridge  3  are mounted on the carriage  4 , the carriage  4  is movable along a carriage shaft  9 . 
     When a driving force from a driving motor (not shown) is transmitted to the carriage  4  through a plurality of gears and a timing belt  7 , the carriage  4  on which the ink jet recording head  10  is mounted moves along the carriage shaft  9 . 
     The position of the carriage  4  in the direction along the carriage shaft  9  is detected by a linear encoder  2 , and the detection signal is sent to a controller (not shown) as positional information. The controller can control ink ejection operation and the like while recognizing the position of the carriage  4  (the ink jet recording head  10 ) based on the positional information from the linear encoder  2 . 
     The ink jet recording apparatus  1  also includes a platen  5  such that a recording sheet  6  which is a recording medium such as a sheet of paper supplied from a sheet feeding mechanism  8  is transported onto the platen  5 . 
     Although the ink jet recording head as an example of liquid ejection head and the liquid ejection apparatus as an example of ink jet recording apparatus have been described in the above embodiments, the invention is directed to the liquid ejection heads and the liquid ejection apparatuses in general and, as a matter of course, the invention can be applied to liquid ejection heads and liquid ejection apparatuses that eject a liquid other than ink. Example of other liquid ejection heads includes, for example, various recording heads used for image recording apparatuses such as a printer, color material ejection heads used for manufacturing of color filters such as a liquid crystal display, organic EL displays, electrode material ejection heads used for forming electrodes such as field emission displays (FED), and bioorganic ejection heads used for manufacturing bio chips. The invention also can be applied to liquid ejection apparatuses having such a liquid ejection head. 
     The entire disclosure of Japanese Patent Application No. 2012-012491, filed Jan. 24, 2012 is incorporated by reference herein.