Abstract:
A disclosed inkjet head includes a liquid chamber formed by a space between a vibrating plate and a nozzle substrate and separated by partitions; a piezoelectric element formed by sequentially laminating a common electrode, a piezoelectric substance and an individual electrode over the space; first to fourth insulating films respectively having first to fourth openings; and a first wiring connected to the individual electrode and pulled through the first and second openings over the common electrode, wherein the first wiring passes through the third opening over the third insulating film, the first wiring is exposed from the fourth opening so as to be externally connected, and the third insulating film and the fourth insulating film are not partly formed above the liquid chamber and formed above the first wiring.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to an inkjet head and an inkjet plotter. 
         [0003]    2. Description of the Related Art 
         [0004]    There is an exemplary technique applied with MicroElectroMechanical System (MEMS) for densely packing an inkjet head using a piezoelectric element. 
         [0005]    The inkjet head is obtained by patterning an individual electrode, an common electrode and a piezoelectric substance on a vibrating plate to thereby form a piezoelectric element as an actuator. 
         [0006]    However, a piezoelectric substance may be degraded by moisture in the air. 
         [0007]    Patent Document 1 discloses a flow path forming substrate on which a pressure generating chamber communicating with nozzle openings for discharging droplets, a piezoelectric element made of a lower electrode provided on one side surface of the flow path forming substrate via a vibrating plate, a piezoelectric substance layer and an upper electrode, and an upper electrode lead electrode drawn out of the upper electrode. At this time, pattern areas in the layers forming the piezoelectric element and the upper electrode lead electrode except for areas facing connection wirings of the lower electrode and the upper electrode lead electrode are coated by an insulating film made of an inorganic amorphous material. The insulating film includes a first insulating film and a second insulating film, and the piezoelectric element except for a connecting portion connected with the upper electrode lead electrode is covered by the first insulating film. The upper electrode lead electrode extends on the first insulating film. The pattern areas of the layers forming the piezoelectric element and the upper electrode lead electrode except for the area facing the connecting portion of the connection wirings is coated by the second insulating layer. 
         [0008]    However, because the upper electrode lead electrode is not formed on the lower electrode, there is a problem that the inkjet head cannot be downsized. 
         [0009]    Patent Document 1: Japanese Laid-Open Patent Application No. 2010-42683 
       SUMMARY OF THE INVENTION 
       [0010]    Accordingly, embodiments of the present invention provide a novel and useful inkjet head and an inkjet plotter solving one or more of the problems discussed above. More specifically, the embodiments of the present invention may provide an inkjet head and an inkjet plotter including the inkjet head with which the piezoelectric substance can be prevented from degrading with the moisture in the air and being highly densely packed and simultaneously downsized. 
         [0011]    One aspect of the embodiments of the present invention may be to provide an inkjet head including a nozzle substrate having a nozzle; a vibrating plate formed above the nozzle substrate; a liquid chamber formed by a space between the vibrating plate and the nozzle substrate and separated by partitions; a piezoelectric element formed by sequentially laminating a common electrode, a piezoelectric substance and an individual electrode over the space, the common electrode extending above the partition; a first insulating film having a first opening; a second insulating film formed on the first insulating film and having a second opening; a third insulating film formed on the second insulating film and having a third opening; a fourth insulating film formed on the third insulating film and having a fourth opening; and a first wiring connected to the individual electrode and pulled through the first opening and the second opening over the common electrode, wherein the first wiring passes through the third opening over the third insulating film, wherein the first wiring is exposed from the fourth opening so as to be externally connected, wherein the third insulating film and the fourth insulating film are not partly formed above the liquid chamber and formed above the first wiring. 
         [0012]    Additional objects and advantages of the embodiments will be set forth in part in the description which follows, and in part will be clear from the description, or may be learned by practice of the invention. Objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
         [0013]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1A  is an exemplary cross-sectional view of a part of an inkjet head of an embodiment of the present invention. 
           [0015]      FIG. 1B  is an exemplary cross-sectional view of a part of the inkjet head of the embodiment of the present invention. 
           [0016]      FIG. 2A  illustrates an exemplary inkjet plotter of the embodiment of the present invention. 
           [0017]      FIG. 2B  illustrates an exemplary inkjet plotter of the embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    A description is given below, with reference to the  FIG. 1A  through  FIG. 2B  of embodiments of the present invention. 
         [0019]    Reference symbols typically designate as follows:
     100 : inkjet head;
         110 : liquid chamber;         111 : nozzle substrate;     111   a : nozzle;     112 : liquid chamber substrate;     112   a : vibrating plate;     112   b : partition;     120 : piezoelectric element;     121 : common electrode;     122 : piezoelectric substance;     123 : individual electrode;     131 ,  132 ,  133 ,  134 : insulating layer;     131   a ,  132   a ,  133   a : opening;     131   b ,  132   b ,  133   b : opening;     134   a ,  134   b : contact hole; and     140 ,  150 : wiring.   
 
         [0036]      FIG. 1A  and  FIG. 1B  are exemplary cross-sectional views of a part of the inkjet head of the embodiment of the present invention.  FIG. 1B  is a cross-sectional view of the part taken along a direction perpendicular to a direction of taking along the part in  FIG. 1A . 
         [0037]    Plural liquid chambers  110  are formed in the inkjet head  100 . The plural liquid chambers  110  are formed by bonding a nozzle substrate  111  having plural nozzles  111   a , a vibrating plate  112   a  arranged on the nozzle substrate  111 , and a liquid chamber substrate  112  having a partition  112   b  using a bond. Said differently, the plural liquid chambers  110  are formed by separating a space between the nozzle substrate  111  and the vibrating plate  112   a  by the partitions  112   b.    
         [0038]    Referring to  FIG. 1A  and  FIG. 1B , only one liquid chamber  110  is illustrated. However, the inkjet head  100  may have plural liquid chambers  110  arranged in a lateral direction of  FIG. 1B . 
         [0039]    Further, a common electrode  121  is formed on the vibrating plate  112   a . A piezoelectric substance  122  and an individual electrode  123  are sequentially formed on the common electrode  121  corresponding to the space separated by the partition  112   b . Said differently, the piezoelectric elements  120  are formed on the spaces separated by the partitions  112   b  of the vibrating plates  112   a.    
         [0040]    Insulating films  131  and insulating films  132  are sequentially formed on the vibrating plates  112   a  formed on the piezoelectric elements  120 , respectively. The insulating films  131  have openings  131   a  at positions corresponding to the individual electrodes  123 , respectively. The insulating films  132  have openings  132   a  at positions corresponding to the individual electrodes  123 , respectively. 
         [0041]    Wirings  140  are drawn onto regions including a part of the common electrode  121  via the openings  131   a  and  132   a  from the individual electrodes, respectively. Insulating films  133  having openings  133   a  through which the wirings  140  are drawn are formed between the insulating film  132  and the region including the wiring  140 . The openings  131   a ,  132   a  and  133   a  form a contact hole. Insulating films  134  having contact holes  134   a  through which wirings (not illustrated) for electrically connecting the wirings  140  and driving circuits (not illustrated) are formed on the wirings  140 . The insulating films  133  and the insulating films  134  are not formed over regions of the spaces separated by the partitions  112   b  except for the regions including the wirings  140 . 
         [0042]    Meanwhile, the insulating films  131  and  132  have openings  131   b  and  132   b , respectively. Wirings  150  are drawn onto regions including parts of the common electrodes  121  from the common electrodes  121  via the openings  131   b  and  132   b . Insulating films  133  having openings  133   a  through which the wirings  150  are drawn are formed between the insulating film  133  and the region including the wiring  150 . The openings  131   a ,  132   a  and  133   a  form a contact hole. Further, insulating films  134  having contact holes  134   b  through which wirings (not illustrated) for electrically connecting the wirings  150  and driving circuits (not illustrated) are formed on the wirings  150 . 
         [0043]    The insulating films  131  coat the vibrating plates  112   a  on which the piezoelectric elements  120  are formed except for the openings  131   a  and the openings  131   b . The insulating films  131  prevent the piezoelectric elements  120  from being etched. 
         [0044]    The material of the insulating film  131  is not specifically limited. The material may be oxides such as Al 2 O 3 , ZrO 2 , Y 2 O 3 , Ta 2 O 3  and TiO 2 , nitrides, carbides or the like or may be two or more of the oxides, the nitrides, the carbides or the like in order to prevent degradation of the piezoelectric elements  120  and displacement of the vibrating plates  112   a.    
         [0045]    The film thicknesses of the insulating films  131  are preferably 20 to 100 nm. If the film thicknesses of the insulating films  131  are less than 20 nm, the piezoelectric element  120  may deteriorate. If the film thicknesses of the insulating films  131  are more than 100 nm, the displacement of the vibrating plates  112   a  may be impaired. 
         [0046]    A method of forming the insulating film  131  is not specifically limited. In order to prevent the degradation of the piezoelectric elements  120 , a vapor-deposition technique and an atomic layer deposition (ALD) technique are preferable, more preferably the ALD technique. 
         [0047]    The insulating films  132  coats the vibrating plate  112   a  on which the piezoelectric element  120  is formed except for the opening  132   a  and the opening  132   b  in a manner similar to the insulating film  131 . At this time, the insulating film  132  is a mask layer used to etch the insulating film  133  to be described later. The film thickness of the region in which the insulating film  133  is formed is greater than a region in which the insulating film  133  is not formed by over-etching. With this, it is possible to prevent the displacement of the piezoelectric element from being impaired to thereby obtain an excellent discharge property of the inkjet head  100 . 
         [0048]    The material of the insulating film  132  is not specifically limited, and may be oxides such as Al 2 O 3 , ZrO 2 , Y 2 O 3 , Ta 2 O 3  and TiO 2 , or may be two or more of the oxides. 
         [0049]    The film thickness of the insulating film  132  at a position laminated below the insulating film  133  is ordinarily 20 to 100 nm. If the film thickness of the insulating film  132  at the position laminated below the insulating film  133  is less than 20 nm, the insulating film  131  in the region where the insulating film  133  is not formed may be etched. If the film thickness of the insulating film  132  at the position laminated below the insulating film  133  is more than 100 nm, the displacement of the vibrating plate  112   a  may be impaired. 
         [0050]    The film thickness of the insulating film  132  at a position not being laminated below the insulating film  133  is ordinarily 5 to 40 nm. If the film thickness of the insulating film  132  at the position not being laminated below the insulating film  133  is less than 5 nm, the insulating film  131  in the region where the insulating film  133  is not formed may be etched. If the film thickness of the insulating film  132  at the position not being laminated below the insulating film  133  is more than 40 nm, the displacement of the vibrating plate  112   a  may be impaired. 
         [0051]    A method of forming the insulating film  132  is not specifically limited. In order to prevent the degradation of the piezoelectric elements  120 , a vapor-deposition technique and an atomic layer deposition (ALD) technique are preferable, more preferably the ALD technique. 
         [0052]    The insulating film  133  is formed together with the insulating films  131  and  132  between the wiring  140  and the common electrode  121 . The insulating film is an inter-layer protection film for preventing insulation breakdown between the wiring  140  and the common electrode  121 . With this, a degree of freedom in arranging the individual electrode  123  and the wiring  140  becomes high. Even if the inkjet head  100  is highly densely packed, it can be downsized. Because the etched insulating film  133  is not formed over the space separated by the partition  112   b  except for the region including the wiring  140 , it is possible to prevent from impairing the displacement of the piezoelectric element  120 . Therefore, the inkjet head  100  is excellent in the discharge property. 
         [0053]    The material of the insulating film  133  is not specifically limited. However, the material may be an inorganic material, i.e., oxides such as SiO 2 , nitrides, carbides or the like or may be two or more of the oxides, the nitrides, the carbides or the like in order to obtain contact with the wiring  140 . 
         [0054]    The film thickness of the insulating film  133  is ordinarily 200 nm or more, more preferably 500 nm or greater. If the film thickness of the insulating film  133  is 200 nm or less, a voltage applied between the common electrode  121  and the wiring  140  may cause insulation breakdown. 
         [0055]    The method of forming the insulating film  133  is not specifically limited, and may be a plasma CVD method, a sputtering method or the like. Because the insulating film can be isotropically formed, a plasma CVD method is preferable. 
         [0056]    The method of etching the insulating film  133  is not specifically limited, and may be a method using photolithography and dry etching. 
         [0057]    The method of forming the contact hole including the openings  131   a ,  132   a  and  133   a  and the contact hole including the openings  131   b ,  132   b  and  133   b  are not specifically limited, and may be a method using photolithography and dry etching. 
         [0058]    The insulating film  134  is a passivation layer which coats the wirings  140  and  150  except for the contact holes  134   a  and the contact holes  134   b  and protect the wirings  140  and  150 . Because the etched insulating film  134  is not formed over the space separated by the partition  112   b  except for the region including the wiring  140 , it is possible to prevent from impairing the displacement of the piezoelectric element  120 . Therefore, the inkjet head  100  is excellent in the discharge property. 
         [0059]    The material of the insulating film  134  is not specifically limited and may be an inorganic material, i.e., oxides, nitrides, carbides or the like, an organic material such as a polyimide, an acrylic resin and an urethane resin, or may be two or more of the inorganic materials and the organic material. Among these materials, the inorganic material is preferable because the material can be patterned by etching. 
         [0060]    The film thickness of the insulating film  134  is ordinarily 200 nm or more, more preferably 500 nm or greater. If the film thickness of the insulating film  134  is 200 nm or smaller, the wirings  140  and  150  may be eroded to cause disconnection. 
         [0061]    The method of forming the insulating film  134  is not specifically limited, and may be a plasma CVD method, a sputtering method or the like. Because the insulating film can be isotropically formed, a plasma CVD method is preferable. 
         [0062]    The method of etching the insulating film  134  is not specifically limited, and may be methods using photolithography and dry etching. 
         [0063]    The material of forming the nozzle substrate  111  is not specifically limited and may be stainless steel and polyimide. 
         [0064]    The liquid chamber substrate  112  can be formed by anisotropically etching a silicon monocrystalline substrate having a plane direction of (100) on which the vibrating plate  112   a  is formed by laminating Si, SIO 2 , Si 3 N 4  with the plasma CVD method. 
         [0065]    The film thickness of the liquid chamber substrate  112  is ordinarily 100 to 600 nm. 
         [0066]    If the piezoelectric substance  122  is a Lead Zirconate Titanate (PZT) having linear expansion coefficient of 8×10 −6 [ 1/K], linear expansion coefficients of the material of the vibrating plate  112   a  is preferably 5×10 −6  to 1×10 −5  to, more preferably 5×10 −6  to 1×10 −5 . 
         [0067]    The material forming the vibrating plate  112   a  may be an aluminum oxide, a zirconium oxide, an iridium oxide, a ruthenium oxide, a tantalum oxide, a hafnium oxide, an osmium oxide, a rhenium oxide, a rhodium oxide, or a palladium oxide, or two or more of these. 
         [0068]    The method of forming the vibrating plate  112   a  is not specifically limited and may be a sputtering method, a sol-gel method or the like. 
         [0069]    The thickness of the vibrating plate  112   a  is ordinarily 0.1 to 10 μm, preferably 0.5 to 3 μm. If the thickness of the vibrating plate  112   a  is less than 0.1 μm, a manufacturing process may be difficult. If the thickness of the vibrating plate  112   a  is greater than 10 μm, the displacement of the vibrating plate  112   a  becomes difficult. 
         [0070]    The material of the common electrode  121  is not specifically limited and may be a conductive metal oxide. 
         [0071]    The conductive metal oxide may preferably be a combined metal oxide containing a major ingredient of a chemical compound expressed by the following formula: ABO 3 , where A represents Sr, Ba, Ca of La and B represents Ru, Co or Ni. 
         [0072]    Exemplary combined metal oxides are SrRuO 3 , CaRuO 3 , (Sr 1-x Ca x )RuO 3 , LaNiO 3 , SrCoO 3 , or (La 1-y Sr y )(Ni 1-y Co y )O 3 . 
         [0073]    A conductive metal oxide other than a combined metal oxide is IrO 2  or RuO 2 . 
         [0074]    The common electrode  121  is a laminated body of a metal and a conductive metal oxide. 
         [0075]    The metal is not specifically limited and may be a platinum group element such as Ru, Rh, Pd, Os, Ir and Pt and an alloy of the platinum group elements. 
         [0076]    It is preferable to form a laminated body of a metal and a conductive metal oxide on Ti, TiO 2 , TiN, Ta, Ta 2 O 5 , Ta 3 N 5  or the like in order to improve contact with the vibrating plate  112   a.    
         [0077]    The method of forming the common electrode is not specifically limited and may be a sputtering method, a sol-gel method or the like. 
         [0078]    The material of the piezoelectric substance  122  is not specifically limited and may be a combined metal oxide such as PZT. PZT is a solid solution of lead zirconate (PbZrO 3 ) and lead titanate (PbTiO 3 ). One of PZT generally showing an excellent piezoelectric property is Pb(Zr 0.53 Ti 0.47 )O 3 . 
         [0079]    The combined metal oxide other than PZT is barium titanate or the like. 
         [0080]    The major ingredient of the combined metal oxide can be expressed by the following formula: ABO 3 , where A represents Pb, Ba or Sr and B represents Ti, Zr, Sn, Ni, Zn, Mg or Nb. 
         [0081]    Exemplary combined metal oxides are (Pb 1-x Ba x )(Zr,Ti)O 3 , (Pb 1-x Sr x )(Zr,Ti)O 3 . These exemplary combined metal oxides are obtained by replacing a part of Pb of PZT with Ba or Sr. Pb of PZT can be replaced by a dyad to enable relaxing degradation of the property caused by evaporation of lead during heat treatment. 
         [0082]    The method of forming the piezoelectric substance  122  is not specifically limited and may be a sputtering method, a sol-gel method or the like. 
         [0083]    The method of patterning the piezoelectric substance  122  is not specifically limited and may be photolithography and etching processes. 
         [0084]    The material of the individual electrode  123  is not specifically limited and may be a conductive metal oxide. 
         [0085]    The conductive metal oxide may preferably be a combined metal oxide containing a major ingredient of a chemical compound expressed by the following formula: ABO 3 , where A represents Sr, Ba, Ca of La and B represents Ru, Co or Ni. 
         [0086]    Exemplary combined metal oxides are SrRuO 3 , CaRuO 3 , (Sr 1-x Ca x )RuO 3 , LaNiO 3 , SrCoO 3 , or (La 1-y Sr y )(Ni 1-y Co y )O 3 . 
         [0087]    A conductive metal oxide other than a combined metal oxide is IrO 2  or RuO 2 . 
         [0088]    The individual electrode  123  may be a laminated body of a conductive metal oxide and a metal. 
         [0089]    The metal is not specifically limited and may be a platinum group element such as platinum and iridium, an Ag alloy, Cu, Al, Au or the like. 
         [0090]    The method of forming the individual electrode  123  is not specifically limited and may be a sputtering method, a sol-gel method or the like. 
         [0091]    The method of patterning the individual electrode  123  is not specifically limited and may be photolithography and etching processes. 
         [0092]    The material of the wirings  140  and  150  is not specifically limited and may be an Ag alloy, Cu, Al, Au, Pt, Ir or the like. 
         [0093]    The method of forming the vibrating plate  112   a  is not specifically limited and may be a sputtering method, a sol-gel method or the like. 
         [0094]    The method of patterning the wirings  140  and  150  is not specifically limited and may be photolithography and etching processes. 
         [0095]    The wirings  140  and  150  are formed by partly reforming surfaces of the insulating film  133  and patterning on the reformed part of the insulating film using an inkjet method. For example, if the material forming the insulating film  133  is an oxide, the surface of the insulating film  133  may be reformed by a silicon analog. As a result, it is possible to directly depict a highly-dense pattern using an inkjet method on a region where surface energy is increased. 
         [0096]    The wirings  140  and  150  can be patterned by conductive paste using screen printing. 
         [0097]    For example, commercialized products of the conductive paste are Perfect Gold (“Perfect Gold” is a registered trademark) being gold paste manufactured by Ulvac Coating Corporation, Perfect Copper being copper paste manufactured by Ulvac Coating Corporation, OrgaconPaste variant 1/4 and Paste variant 1/3 being Transparent Printing Ink PEDOT/PSS manufactured by Agfa-Gevaert Japan, Ltd, OrgaconCarbon Paste variant 2/2 being carbon electrode paste manufactured by Agfa-Gevaert Japan, Ltd, BAYTRON (BAYTRON (Upper case) is a registered trademark) being PEDT/PSS aqueous solution manufactured by Starck-V TECH Japan, Ltd. 
         [0098]    The thickness of the wirings  140  and  150  is ordinarily 0.1 to 20 μm, preferably 0.2 to 10 μm. If the thickness of the wirings  140  and  150  is smaller than 0.1 μm, the resistances of the wirings  140  and  150  may increase. If the thickness of the wirings  140  and  150  is greater than 20 μm, the process time may be extended. 
         [0099]      FIG. 2A  and  FIG. 2B  are an exemplary inkjet plotter of the inkjet head of the embodiment of the present invention.  FIG. 2A  is a perspective view of the exemplary inkjet plotter, and  FIG. 2B  is a side view of a mechanical portion. 
         [0100]    An inkjet plotter  200  includes inside a main body  201  a carriage  202 , an inkjet head  203  installed in the carriage  202 , and a print mechanism unit  205  including an ink cartridge  204 . A lower portion of the inkjet plotter  200  can be freely loaded with or unloaded from a paper feed cassette  206  which can receive paper P from a front side of the paper feed cassette and stack the paper P. Further, the lower portion of the inkjet plotter  200  has a manual paper feed tray  207  which is opened for manually feeding paper P. The inkjet plotter  200  takes the paper P fed from the paper feed cassette  206  or the manual paper feed tray  207  in, copies (records) an image onto a paper by the print mechanism unit  205 , and ejects the copied paper to a copy receiving tray  208 . 
         [0101]    The carriage  202  is held by a main guide rod  209  laterally supported by right and left side plates (not illustrated) and a sub guide rod  210  so that the carriage  202  freely slides in a main scanning direction. The inkjet head  203  for discharging various colored ink of yellow (Y), cyan (C), magenta (M) and black (Bk) is attached to the carriage  202 . Plural nozzles are included in the inkjet head  203  and arranged in a direction perpendicular to the main scanning direction so as to downwardly discharge the ink. The ink cartridges  204  for supplying various colored ink to the inkjet head  203  are attached to the carriage  202  so that the ink cartridges  204  are replaceable. 
         [0102]    An air vent (not illustrated) communicating with the air is formed on an upper side if the ink cartridge  204 , and a supply port for supplying the ink to the inkjet head  203  is downwardly formed. A porous body (not illustrated) filled with the ink is installed inside the ink cartridge. At this time, capillary force caused by the porous body maintains the ink supplied to the inkjet head  203  to have slightly negative pressure. 
         [0103]    Instead of arranging the inkjet heads discharging the colored ink, one inkjet head for discharging various colored ink may be provided. 
         [0104]    The carriage  202  is supported by the main guide rod  209  on a downstream side relative to a carrying direction of the paper P so as to be freely slidable along the main guide rod  209 , and an upstream side relative to the carrying direction of the paper P is supported by the sub guide rod  210  so as to be freely slidable along the sub guide rod  210 . A timing belt  214  bridges to connects a driving pulley  212  rotated by a main scanning motor  211  and a driven pulley  213 . The timing belt is partly fixed to the carriage  202 . By rotating the main scanning motor  211 , the carriage  202  can be moved in the main scanning direction. 
         [0105]    On the other hand, in order to carry the paper P stacked on the paper feed cassette  206  below the inkjet head  203 , there are provided a paper feed roller  215  for separating and carrying the paper P from the paper feed cassette  206 , a friction pad  216 , a guide member  217  for guiding the paper P, a carrying roller  218  for inverting the paper P and carry the paper, a carrying wheel  219  pressed on a peripheral surface of the carrying roller  218 , and a top end wheel  220  determining an angle of sending the paper P from the carrying roller  218 . The carrying roller  218  is rotated by the sub scanning motor  221  via a gear array (not illustrated). 
         [0106]    Further, a guide member  222  is provided to guide the paper P sent by the carrying roller  218  below the inkjet head  203  within a movement range of the carriage  202  in the main scanning direction. On the downstream side of the carrying direction of the paper P relative to the guide member  222 , there are provided a carrying wheel  223  and a spur  224  which are rotated to eject the paper P. Further, there are provided guide members  225  and  226  for guiding the paper P sent by the carrying wheel  223  and the spur  224 , a copy ejecting roller  227  for sending the paper P guided by the guide members  225  and  226  to the copy receiving tray  208  and a spur  228 . 
         [0107]    When an image is recorded on the paper P, the inkjet head  203  is moved while moving the carriage  202  in response to an image signal. For example, after discharging an ink onto a stopping paper P to record one line, the paper P is carried by the one line, and recording and carrying are repeated. When a signal indicating that the image is completely recorded or a signal indicating that the back end of the paper P reaches a recording area are received, an operation of recording the image is completed and the paper P is ejected. 
         [0108]    At a position outside the recording area on the right side of the moving direction of the carriage  202 , a recovery device  229  for recovering from discharge failure of the inkjet head  203  is provided. The recovery device  229  includes a cap unit (not illustrated), a suction unit (not illustrated) and a cleaning unit (not illustrated). While the carriage  202  waits for the recording, the carriage  202  is moved on the side of the recovery device  229  so that the inkjet head  203  is capped by a capping unit to maintain the nozzle in a wet state. Thus, the discharge failure caused by drying of the ink can be prevented. Further, degrees of viscosity of the ink from the nozzles are made constant to maintain stable discharging capability by discharging the ink which is not related to recording of the image while the image is recorded. 
         [0109]    When the discharge failure occurs, the nozzle of the inkjet head  203  causing the discharge failure is sealed by the capping unit, the ink and air bubbles are sucked by the suction unit via a tube, and the ink, dust and so on (adhered to the nozzle) are removed to thereby recover from the discharge failure. At this time, the ink sucked by the suction unit is ejected to a waste ink reservoir provided below the main body  201  and sucked and retained by an ink absorber. 
       Embodiments 
     Synthesis of a PZT Precursor Solution 
       [0110]    After dissolving lead acetate trihydrate in methoxyethanol, the solution is dehydrated to thereby obtain a methoxyethanol solution of lead acetate trihydrate. Meanwhile, after dissolving titanium isopropoxide and zirconium isopropoxide in methoxyethanol, the solution undergoes an alcoholysis reaction and an esterification reaction. Next, the methoxyethanol solution of lead acetate trihydrate is added to it to thereby obtain a PZT precursor solution of 0.5 mol/L. In order to avoid degradation of crystallographic quality due to so-called “lead extraction” during heat processing, lead of 10 mol % is excessively added relative to the stoichiometric composition. 
       Example 1 
       [0111]    A thermally-oxidized film (the vibrating plate  112   a ) having a thickness of 1 μm is formed on a silicon wafer. A laminated body of a titanium film having a thickness of 50 nm, a platinum film having a thickness of 200 nm and a SrRuO 3  film having a thickness of 100 nm are formed on the thermally-oxidized film by sputtering. 
         [0112]    The PZT precursor solution is coated on the laminated body by a spin coat method, dried at 120° C. and thermally decomposed at 500° C. This process is repeated three times. Thereafter, the processed laminated body is crystallized by a rapid thermal processing (RTA) at 700° C. The above processes are repeated four times to thereby form a Pb(Zr 0.53 Ti 047 )O 3  film having a film thickness of 1 μm. 
         [0113]    Next, a laminated body of a SrRuO 3  film having a thickness of 100 nm and a platinum film having a thickness of 100 nm is formed on the Pb(Zr 0.53 Ti 0.47 )O 3  film. 
         [0114]    Next, a photo resist TSMR8800 manufactured by Tokyo Ohka Kogyo Co., Ltd. is coated on the above laminated body by a spin coating method. Then, a resist pattern is formed by photolithography and patterned using an inductively-coupled plasma (ICP) etching device manufactured by SAMCO Inc. to thereby form the piezoelectric element  120  as illustrated in  FIG. 1 . 
         [0115]    Next, an Al 2 O 3  film (the insulating film  131 ) having a thickness of 50 nm is formed by an ALD method on the vibrating plate  112   a  on which the piezoelectric element  120  is formed. At this time, raw materials of Al and O are TMA manufactured by Sigma-Aldrich Co. LLC and O 3  generated by an ozone generator. Ai and O are alternately laminated to form the Al 2 O 3  film. 
         [0116]    Next, a ZrO 2  film (the insulating film  132 ) having a thickness of 50 nm is formed by an ALD method on the insulating film  131 . At this time, raw materials of Zr and O are Zr(OC(CH 3 ) 3 ) 4  manufactured by Sigma-Aldrich Co. LLC and O 3  generated by an ozone generator. Zr and O are alternately laminated to form the ZrO 2  film. 
         [0117]    Next, after forming an SiO 2  film having a thickness of 500 nm on the insulating film  132  using a plasma CVD method, a contact hole is formed by etching to thereby form the insulating film  133 . 
         [0118]    Next after forming an Al film using sputtering, the wirings  140  and  150  are formed by patterning using etching. 
         [0119]    Next, after forming an Si 3 N 4  film having a thickness of 1 μm on the wirings  140  and  150  using a plasma CVD method, a contact hole is formed by etching to thereby form the insulating film  134 . 
         [0120]    Next, portions of the insulating films  134  and  133  over the space separated by the partition walls  112   b  except for portions corresponding to the wiring  140  are continuously etched. As a result, the film thickness of the portion without the insulating film  133  is 37 nm. Further, the contact holes  134   a  and  134   b  are formed by etching. 
         [0121]    Next, after forming the partitions  112   b  by etching the silicon wafer, it is connected to the nozzle substrate  111  having the nozzle  111   a  to thereby obtain the inkjet head  100 . 
       Example 2 
       [0122]    Except for the film thicknesses of 20 nm of the Al 2 O 3  film (the insulating film  131 ) and the ZrO 2  film (the insulating film  132 ), the inkjet head  100  is obtained in a similar manner to the Example 1. As a result, the film thickness of the portion without the insulating film  133  is 9 nm. 
       Example 3 
       [0123]    Except for the film thicknesses of 100 nm of the Al 2 O 3  film (the insulating film  131 ) and the ZrO 2  film (the insulating film  132 ), the inkjet head  100  is obtained in a similar manner to the Example 1. As a result, the film thickness of the portion without the insulating film  133  is 25 nm. 
       Comparative Example 1 
       [0124]    Except that the ZrO 2  film (the insulating film  132 ) is not formed, an inkjet head is obtained in a similar manner to the Example 1. 
       Electric Property 
       [0125]    Electric properties of the inkjet heads of Examples 1 to 3 and Comparative Example 1 are evaluated. Then, after the inkjet head is left uncontrolled under circumstances of 80° C. and 85% RH, an electric property is evaluated. 
         [0126]    A saturation polarization Ps [° C./cm 2 ] under electric field intensity of 150 kV/cm is measured as an electric property. 
       Discharge Property 
       [0127]    A voltage of −10 to −30 V in a simple Push waveform is applied between the common electrode  121  and an individual electrode  123  of the inkjet heads of the Examples 1 to 3 and the Comparative Example 1 to thereby evaluate discharging of ink having viscosity of 5 cp. The evaluation is as follows. A case where the ink can be discharged is marked by o, and a case where the ink cannot be discharged is marked by x. 
         [0128]    The evaluation results of the electric property and the discharge property are indicated in Table 1. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 ELECTRIC PROPERTY Ps 
                   
               
               
                   
                 [μC/cm 2 ] 
               
             
          
           
               
                   
                   
                 AFTER 
                   
               
               
                   
                   
                 LEAVING FOR 
               
               
                   
                 INITIAL 
                 PREDETERMINED 
                 DISCHARGE 
               
               
                   
                 STAGE 
                 TIME 
                 PROPERTY 
               
               
                   
                   
               
             
          
           
               
                 EXAMPLE 1 
                 47 
                 47 
                 ◯ 
               
               
                 EXAMPLE 2 
                 48 
                 48 
                 ◯ 
               
               
                 EXAMPLE 3 
                 46 
                 45 
                 ◯ 
               
               
                 COMPARATIVE 
                 47 
                 26 
                 ◯ 
               
               
                 EXAMPLE 1 
               
               
                   
               
             
          
         
       
     
         [0129]    Referring to Table 1, the inkjet head of the Examples 1 to 3 are excellent in the discharge property and can suppress degradation of the piezoelectric substance caused by moisture in the air. 
         [0130]    On the other hand, the piezoelectric substance of the inkjet head of the Comparative Example is degraded by moisture in the air. This degradation in the Comparative Example is supposed to be caused because the ZrO 2  film (the insulating film  132 ) is not formed and therefore the Al 2 O 3  film (the insulating film  131 ) is etched in continuously etching the insulating films  134  and  135 . 
         [0131]    Accordingly, embodiments of the present invention provide a novel and useful inkjet head and an inkjet plotter solving one or more of the problems discussed above. More specifically, the embodiments of the present invention may provide an inkjet head and an inkjet plotter including the inkjet head with which the piezoelectric substance can be prevented from degrading with the moisture in the air and being highly densely packed and simultaneously downsized. 
         [0132]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority or inferiority of the invention. Although the embodiment of the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations could be made thereto without departing from the spirit and scope of the invention. 
         [0133]    This patent application is based on Japanese Priority Patent Application No. 2011-049677 filed on Mar. 7, 2011, the entire contents of which are hereby incorporated herein by reference.