Patent Publication Number: US-11020968-B2

Title: Head chip, liquid jet head, liquid jet recording device, and method of manufacturing head chip

Description:
RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application Nos. 2018-211523 filed on Nov. 9, 2018, the entire content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a head chip, a method of manufacturing the same, a liquid jet head, and a liquid jet recording device. 
     2. Description of the Related Art 
     As one of liquid jet recording devices, there is provided an inkjet type recording device for ejecting (jetting) ink (liquid) on a recording target medium such as recording paper to perform recording of images, characters, and so on (see, e.g., the specification of U.S. Pat. No. 8,091,987). 
     In the liquid jet recording device of this type, it is arranged so that the ink is supplied from an ink tank to an inkjet head (a liquid jet head), and then the ink is ejected from nozzle holes of the inkjet head toward the recording target medium to thereby perform recording of the images, the characters, and so on. Further, such an inkjet head is provided with a head chip for ejecting the ink. 
     In such a head chip and so on, for example, there is a possibility that the ejection speed varies due to a stray capacitance, and thus, the image quality degrades. Therefore, it is desirable to provide a head chip and a method of manufacturing the same, a liquid jet head, and a liquid jet recording device each capable of suppressing the stray capacitance to improve the image quality. 
     SUMMARY OF THE INVENTION 
     The head chip according to an embodiment of the present disclosure is a head chip adapted to jet liquid including an actuator plate adapted to apply pressure to the liquid, wherein the actuator plate includes an obverse surface and a reverse surface, a channel extending in a predetermined direction, and having a first opening provided to the obverse surface and a second opening which is provided to the reverse surface and is shorter in length in the predetermined direction than the first opening, and an electrode having an obverse surface side part disposed on a sidewall of the channel on the first opening side, and a reverse surface side part which is disposed on the sidewall closer to the second opening than the obverse surface side part and is one of equal to and larger than the obverse surface side part in size in the predetermined direction. 
     The liquid jet head according to an embodiment of the present disclosure includes the head chip according to an embodiment of the disclosure, and a supply mechanism adapted to supply the liquid to the head chip. 
     The liquid jet recording device according to an embodiment of the present disclosure includes the liquid jet head according to an embodiment of the present disclosure, and a containing section adapted to contain the liquid. 
     The method of manufacturing a head chip according to an embodiment of the present disclosure is a method of manufacturing a head chip including an actuator plate adapted to apply pressure to liquid so as to jet the liquid, the method including forming the actuator plate, the forming the actuator plate including providing a piezoelectric substrate having an obverse surface and a reverse surface with a channel which extends in a predetermined direction and has a first opening on the obverse surface, covering both end parts of the first opening in the predetermined direction with a mask, evaporating a conductive material on a sidewall of the channel from the first opening provided with the mask so as to form a first evaporation part, grinding the reverse surface of the piezoelectric substrate so as to reach the channel, to thereby form a second opening shorter in length in the predetermined direction than the first opening on the reverse surface side of the piezoelectric substrate, and evaporating the conductive material on the sidewall of the channel from the second opening so as to form a second evaporation part, to thereby form an electrode including the first evaporation part and the second evaporation part. 
     According to the head chip, the method of manufacturing the same, the liquid jet head, and the liquid jet recording device related to an embodiment of the present disclosure, it becomes possible to suppress the stray capacitance to improve the image quality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view showing a schematic configuration example of a liquid jet recording device according to an embodiment of the present disclosure. 
         FIG. 2  is a schematic diagram showing a detailed configuration example of a circulation mechanism and so on shown in  FIG. 1 . 
         FIG. 3  is an exploded perspective view showing a detailed configuration example of the liquid jet head shown in  FIG. 2 . 
         FIG. 4  is a perspective view showing a configuration example of a reverse surface of the actuator plate shown in  FIG. 3 . 
         FIG. 5  is a schematic diagram showing a configuration example of the cross-section along the line A-A shown in  FIG. 3 . 
         FIG. 6  is a schematic diagram showing a configuration example of the cross-section along the line B-B shown in  FIG. 3 . 
         FIG. 7  is a schematic diagram showing an example of a relationship between the ejection channel and the common electrodes shown in  FIG. 3 . 
         FIG. 8  is a schematic diagram showing a configuration example of a part of the cross-section along the line C-C shown in  FIG. 3 . 
         FIG. 9A  is a flow chart showing an example of a method of manufacturing the liquid jet head shown in  FIG. 3  and so on. 
         FIG. 9B  is a flow chart showing a process following the process shown in  FIG. 9A . 
         FIG. 10A  is a schematic cross-sectional view for explaining one process of a method of manufacturing the liquid jet head shown in  FIG. 9A . 
         FIG. 10B  is a schematic cross-sectional view showing a process following the process shown in  FIG. 10A . 
         FIG. 10C  is a schematic cross-sectional view showing a process following the process shown in  FIG. 10B . 
         FIG. 10D  is a schematic cross-sectional view showing a process following the process shown in  FIG. 10C . 
         FIG. 10E  is a schematic cross-sectional view showing a process following the process shown in  FIG. 10D . 
         FIG. 10F  is a schematic cross-sectional view showing a process following the process shown in  FIG. 10E . 
         FIG. 10G  is a schematic cross-sectional view showing a process following the process shown in  FIG. 10F . 
         FIG. 10H  is a schematic cross-sectional view showing a process following the process shown in  FIG. 10G . 
         FIG. 11A  is a schematic plan view for explaining the process of the step S 5  shown in  FIG. 9A . 
         FIG. 11B  is a schematic cross-sectional view corresponding to  FIG. 11A . 
         FIG. 12  is a schematic diagram for explaining the area shown in  FIG. 11B . 
         FIG. 13  is a schematic diagram showing a configuration of a substantial part of a liquid jet head related to a comparative example. 
         FIG. 14  is a schematic diagram showing a configuration of a substantial part of a liquid jet head related to a comparative example. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present disclosure will hereinafter be described in detail with reference to the drawings. It should be noted that the description will be presented in the following order: 
     1. Embodiment (a side-shoot type liquid jet head in which an actuator plate is provided with an electrode including an obverse side part and a reverse side part) 
     2. Modified Example (an example of an edge-shoot type liquid jet head) 
     3. Other Modified Examples 
     &lt;1. Embodiment&gt; 
     [Overall Configuration of Printer  1 ] 
       FIG. 1  is a perspective view schematically showing a schematic configuration example of a printer  1  according to an embodiment of the present disclosure. The printer  1  corresponds to a specific example of a “liquid jet recording device” in the present disclosure. The printer  1  is an inkjet printer for performing recording (printing) of images, characters, and the like on recording paper P as a recording target medium using ink  9  described later. Although the details will be described later, the printer  1  is also an ink circulation type inkjet printer using the ink  9  being circulated through a predetermined flow channel. 
     As shown in  FIG. 1 , the printer  1  is provided with a pair of carrying mechanisms  2   a ,  2   b , ink tanks  3 , inkjet heads  4 , circulation mechanisms  5  and a scanning mechanism  6 . These members are housed in a housing  10  having a predetermined shape. It should be noted that the scale size of each of the members is accordingly altered so that the member is shown large enough to recognize in the drawings used in the description of the specification. The inkjet heads  4  (inkjet heads  4 Y,  4 M,  4 C and  4 K described later) correspond to a specific example of a “liquid jet head” in the present disclosure. 
     (Carrying Mechanisms  2   a ,  2   b ) 
     The carrying mechanisms  2   a ,  2   b  are each a mechanism for carrying the recording paper P along the carrying direction d (an X-axis direction) as shown in  FIG. 1 . These carrying mechanisms  2   a ,  2   b  each have a grit roller  21 , a pinch roller  22  and a drive mechanism (not shown). The grit roller  21  and the pinch roller  22  are each disposed so as to extend along a Y-axis direction (the width direction of the recording paper P). The drive mechanism is a mechanism for rotating (rotating in a Z-X plane) the grit roller  21  around an axis, and is configured using, for example, a motor. 
     (Ink Tanks  3 ) 
     The ink tanks  3  are each a tank for containing the ink  9  to be supplied to the corresponding inkjet head  4 . The ink  9  corresponds to a specific example of a “liquid” in the present disclosure. The ink tanks  3  are each a tank for containing the ink  9  inside. As the ink tanks  3 , there are disposed  4  types of tanks for individually containing  4  colors of ink  9 , namely yellow (Y), magenta (M), cyan (C), and black (K), in this example as shown in  FIG. 1 . Specifically, there are disposed the ink tank  3 Y for containing the yellow ink  9 , the ink tank  3 M for containing the magenta ink  9 , the ink tank  3 C for containing the cyan ink  9 , and the ink tank  3 K for containing the black ink  9 . These ink tanks  3 Y,  3 M,  3 C, and  3 K are arranged side by side along the X-axis direction inside the housing  10 . It should be noted that the ink tanks  3 Y,  3 M,  3 C, and  3 K have the same configuration except the color of the ink  9  contained, and are therefore collectively referred to as ink tanks  3  in the following description. The ink tanks  3  each correspond to a specific example of a “containing section” in the present disclosure. 
     (Inkjet Heads  4 ) 
     The inkjet heads  4  are each a head for jetting (ejecting) the ink  9  shaped like a droplet from a plurality of nozzle holes (nozzle holes H 1 , H 2 ) described later to the recording paper P to thereby perform recording of images, characters, and so on. As the inkjet heads  4 , there are also disposed four types of heads for individually jetting the four colors of ink  9  respectively contained in the ink tanks  3 Y,  3 M,  3 C, and  3 K described above in this example as shown in  FIG. 1 . Specifically, there are disposed the inkjet head  4 Y for jetting the yellow ink  9 , the inkjet head  4 M for jetting the magenta ink  9 , the inkjet head  4 C for jetting the cyan ink  9 , and the inkjet head  4 K for jetting the black ink  9 . These inkjet heads  4 Y.  4 M,  4 C and  4 K are arranged side by side along the Y-axis direction inside the housing  10 . 
     It should be noted that the inkjet heads  4 Y,  4 M,  4 C and  4 K have the same configuration except the color of the ink  9  used therein, and are therefore collectively referred to as inkjet heads  4  in the following description. Further, the detailed configuration of the inkjet heads  4  will be described later ( FIG. 3  through  FIG. 8 ). 
     (Circulation Mechanisms  5 ) 
     The circulation mechanisms  5  are each a mechanism for circulating the ink  9  between the inside of the ink tank  3  and the inside of the inkjet head  4 .  FIG. 2  is a diagram schematically showing a configuration example of the circulation mechanism  5  together with the ink tank  3  and the inkjet head  4 . It should be noted that the solid arrow described in  FIG. 2  indicates the circulation direction of the ink  9 . As shown in  FIG. 2 , the circulation mechanism  5  is provided with a predetermined flow channel (a circulation channel  50 ) for circulating the ink  9 , and a pair of liquid feeding pumps  52   a ,  52   b.    
     The circulation channel  50  is a flow channel of circulating between the inside of the inkjet head  4  and the outside (the inside of the ink tank  3 ) of the inkjet head  4 , and is arranged that the ink  9  circularly flows through the circulation channel  50 . The circulation channel  50  has, for example, a flow channel  50   a  as a part extending from the ink tank  3  to the inkjet head  4 , and a flow channel  50   b  extending from the inkjet head  4  to the ink tank  3 . In other words, the flow channel  50   a  is a flow channel through which the ink  9  flows from the ink tank  3  toward the inkjet head  4 . Further, the flow channel  50   b  is a flow channel through which the ink  9  flows from the inkjet head  4  toward the ink tank  3 . 
     The liquid feeding pump  52   a  is disposed on the flow channel  50   a , between the ink tank  3  and the inkjet head  4 . The liquid feeding pump  52   a  is a pump for feeding the ink  9  contained inside the ink tank  3  to the inside of the inkjet head  4  via the flow channel  50   a . The liquid feeding pump  52   b  is disposed on the flow channel Sob between the inkjet head  4  and the ink tank  3 . The liquid feeding pump  52   b  is a pump for feeding the ink  9  contained inside the inkjet head  4  to the inside of the ink tank  3  via the flow channel  50   b.    
     (Scanning Mechanism  6 ) 
     The scanning mechanism  6  is a mechanism for making the inkjet heads  4  perform a scanning operation along the width direction (the Y-axis direction) of the recording paper P. As shown in  FIG. 1 , the scanning mechanism  6  has a pair of guide rails  61   a ,  61   b  disposed so as to extend along the Y-axis direction, a carriage  62  movably supported by these guide rails  61   a ,  61   b , and a drive mechanism  63  for moving the carriage  62  along the Y-axis direction. Further, the drive mechanism  63  has a pair of pulleys  631   a ,  631   b  disposed between the guide rails  61   a ,  61   b , an endless belt  632  wound between the pair of pulleys  631   a ,  631   b , and a drive motor  633  for rotationally driving the pulley  631   a.    
     The pulleys  631   a ,  631   b  are respectively disposed in areas corresponding to the vicinities of both ends in each of the guide rails  61   a ,  61   b  along the Y-axis direction. To the endless belt  632 , there is coupled the carriage  62 . On the carriage  62 , the four types of inkjet heads  4 Y,  4 M,  4 C and  4 B described above are disposed so as to be arranged side by side along the Y-axis direction. It should be noted that such a scanning mechanism  6  and the carrying mechanisms  2   a ,  2   b  described above constitute a moving mechanism for moving the inkjet heads  4  relatively to the recording paper P. 
     [Detailed Configuration of Inkjet Head  4 ] 
     Then, the detailed configuration example of each of the inkjet heads  4  will be described with reference to  FIG. 3  through  FIG. 8  in addition to  FIG. 1  and  FIG. 2 .  FIG. 3  is an exploded perspective view showing the detailed configuration example of the inkjet head  4 .  FIG. 4  is a perspective view showing a configuration example of a reverse surface of the actuator plate  42  (described later) shown in  FIG. 3 .  FIG. 5  is a diagram schematically showing a configuration example of the cross-section along the line A-A shown in  FIG. 3 .  FIG. 6  is a diagram schematically showing a configuration example of the cross-section along the line B-B shown in  FIG. 3 .  FIG. 7  is a diagram schematically showing a relationship between each of ejection grooves (ejection channels C 1   e  described later) of the actuator plate  42  and an electrode (a common electrode Edc described later) disposed in each of the ejection grooves,  FIG. 8  is a diagram schematically showing a configuration example of a part of the cross-section along the line C-C shown in  FIG. 3 . 
     The inkjet heads  4  according to the present embodiment are each an inkjet head of a so-called side-shoot type for ejecting the ink  9  from a central part in the extending direction (the Y-axis direction) of each of a plurality of channels (channels C 1 , C 2 ) described later. Further, the inkjet heads  4  are each an inkjet head of a circulation type which uses the circulation mechanism  5  (the circulation channel  50 ) described above to thereby use the ink  9  while circulating the ink  9  between the inkjet head  4  and the ink tank  3 . 
     As shown in  FIG. 8 , the inkjet heads  4  are each provided with a head chip  4   c  and a flow channel plate  45 . The head chip  4   c  is mainly provided with a nozzle plate  41 , an actuator plate  42 , and a cover plate  43 . The nozzle plate  41 , the actuator plate  42 , and the cover plate  43  are bonded to each other using, for example, an adhesive, and are stacked on one another in this order along the Z-axis direction. The flow channel plate  45  is bonded to the cover plate  43 . It should be noted that the description will hereinafter be presented with the cover plate  43  side along the Z-axis direction referred to as an upper side, and the nozzle plate  41  side referred to as a lower side. Here, the head chip  4   c  corresponds to a specific example of a “head chip” in the present disclosure, and the “flow channel plate  45 ” corresponds to a specific example of a “supply mechanism” in the present disclosure. 
     (Nozzle Plate  41 ) 
     The nozzle plate  41  is a plate used in the inkjet head  4 . The nozzle plate  41  has a resin substrate or a metal substrate having a thickness of, for example, about 50 μm, and is bonded to a lower surface of the actuator plate  42  as shown in  FIG. 3 . As a material of the resin substrate used as the nozzle plate  41 , there can be cited polyimide and so on. As a material of the metal substrate used as the nozzle plate  41 , there can be cited stainless steel such as SUS  316  or SUS  304 . The nozzle plate  41  is lower in rigidity compared to, for example, the actuator plate  42 . Further, the nozzle plate  41  is flexible compared to, for example, the actuator plate  42 . Further, as shown in  FIG. 3  and  FIG. 4 , the nozzle plate  41  has two nozzle columns (nozzle columns  411 ,  412 ) each extending along the X-axis direction. These nozzle columns  411 ,  412  are arranged along the Y-axis direction at a predetermined distance. As described above, the inkjet heads  4  of the present embodiment are each formed as a two-column type inkjet head. 
     The nozzle column  411  has a plurality of nozzle holes H 1  formed in alignment with each other at predetermined intervals along the X-axis direction. These nozzle holes H 1  are provided one-to-one to the ejection channels C 1   e  described later. These nozzle holes H 1  each penetrate the nozzle plate  41  along the thickness direction (the Z-axis direction) of the nozzle plate  41 , and are communicated with the respective ejection channels C 1   e  in the actuator plate  42  described later as shown in, for example,  FIG. 5  and  FIG. 6 . Specifically, as shown in  FIG. 3 , each of the nozzle holes H 1  is formed so as to be located in a central part along the Y-axis direction below the ejection channel C 1   e . Further, the formation pitch along the X-axis direction in the nozzle holes H 1  is arranged to be equal to the formation pitch along the X-axis direction in the ejection channels C 1   e . Although the details will be described later, the ink  9  supplied from the inside of the ejection channel C 1   e  is ejected (jetted) from the nozzle hole H 1  in such a nozzle column  411 . 
     The nozzle column  412  similarly has a plurality of nozzle holes H 2  formed in alignment with each other at predetermined intervals along the X-axis direction. These nozzle holes H 2  are provided one-to-one to the ejection channels C 2   e  described later. Each of these nozzle holes H 2  also penetrates the nozzle plate  41  along the thickness direction of the nozzle plate  41 , and is communicated with the ejection channel C 2   e  in the actuator plate  42  described later as shown in, for example,  FIG. 5  and  FIG. 6 . Specifically, as shown in  FIG. 3 , each of the nozzle holes H 2  is formed so as to be located in a central part along the Y-axis direction below the ejection channel C 2   e . Further, the formation pitch along the X-axis direction in the nozzle holes H 2  is arranged to be equal to the formation pitch along the X-axis direction in the ejection channels C 2   e . Although the details will be described later, the ink  9  supplied from the inside of the ejection channel C 2   e  is ejected (jetted) also from the nozzle hole H 2  in such a nozzle column  412 . 
     (Actuator Plate  42 ) 
     The actuator plate  42  is a plate formed of a piezoelectric material such as lead zirconate titanate (PZT), and has an obverse surface  42   f   1  and a reverse surface  42   f   2 . The obverse surface  42   f   1  is an opposed surface to the cover plate  43 , and the reverse surface  42   f   2  is an opposed surface to the nozzle plate  41 . The actuator plate  42  is, for example, a so-called chevron type actuator formed by stacking two piezoelectric substrates different in polarization direction in the thickness direction (the Z-axis direction) on one another. It should be noted that it is also possible for the actuator plate  42  to be a so-called cantilever type (a monopole type) actuator formed of a single piezoelectric substrate having the polarization direction set to one direction along the thickness direction (the Z-axis direction). Further, as shown in  FIG. 3  and  FIG. 4 , the actuator plate  42  has two channel columns (channel columns  421 ,  422 ) each extending along the X-axis direction. These channel columns  421 ,  422  are arranged along the Y-axis direction at a predetermined distance. 
     As shown in  FIG. 3  and  FIG. 4 , the channel column  421  has the plurality of channels C 1  each extending along the Y-axis direction. These channels C 1  are arranged side by side so as to be parallel to each other at predetermined intervals along the X-axis direction. Each of the channels C 1  is defined by drive walls Wd formed of a piezoelectric body (the actuator plate  42 ), and forms a groove section penetrating the actuator plate  42  in the thickness direction. Here, the Y-axis direction corresponds to a specific example of a “predetermined direction” in the present disclosure, and the drive wall Wd corresponds to a specific example of a “sidewall” in the present disclosure. 
     As shown in  FIG. 3  and  FIG. 4 , the channel column  422  similarly has the plurality of channels C 2  each extending along the Y-axis direction. These channels C 2  are arranged side by side so as to be parallel to each other at predetermined intervals along the X-axis direction. Each of the channels C 2  is also defined by the drive walls Wd described above, and forms a groove section penetrating the actuator plate  42  in the thickness direction. 
     Here, as shown in  FIG. 3  and  FIG. 4 , the channels C 1  are configured including the ejection channels C 1   e  for ejecting the ink  9 , and non-ejection channels C 1   d  not ejecting the ink  9 . In the channel column  421 , the ejection channels C 1   e  and the non-ejection channels C 1   d  are alternately disposed along the X-axis direction. Each of the ejection channels C 1   e  is an ejection groove communicated with the nozzle hole H 1  in the nozzle plate  41 . In other words, each of the ejection channels C 1   e  forms the groove section penetrating the actuator plate  42  in the thickness direction. The obverse surface  42   f   1  of the actuator plate  42  is provided with openings h 1  communicated with the respective ejection channels C 1   e , and the reverse surface  42   f   2  is provided with openings h 5  communicated with the respective ejection channels C 1   e.    
     In contrast, each of the non-ejection channels C 1   d  is a non-ejection groove which is not communicated with the nozzle hole H 1 , and is covered with an upper surface of the nozzle plate  41  from below. For example, each of the non-ejection channels C 1   d  forms the groove section penetrating the actuator plate  42 . The obverse surface  42   f   1  of the actuator plate  42  is provided with openings h 2  communicated with the respective non-ejection channels C 1   d , and the reverse surface  42   f   2  is provided with openings h 6  communicated with the respective non-ejection channels C 1   d . It is also possible for each of the non-ejection channels C 1   d  to form a groove section which does not penetrate the actuator plate  42 . 
     Similarly, the channels C 2  are configured including the ejection channels C 2   e  for ejecting the ink  9 , and non-ejection channels C 2   d  not ejecting the ink  9 . In the channel column  422 , the ejection channels C 2   e  and the non-ejection channels C 2   d  are alternately disposed along the X-axis direction. Each of the ejection channels C 2   e  is an ejection groove communicated with the nozzle hole H 2  in the nozzle plate  41 . In other words, each of the ejection channels C 2   e  forms the groove section penetrating the actuator plate  42  in the thickness direction. The obverse surface  42   f   1  of the actuator plate  42  is provided with openings h 1  communicated with the respective ejection channels C 2   e , and the reverse surface  42   f   2  is provided with openings h 8  communicated with the respective ejection channels C 2   e.    
     In contrast, each of the non-ejection channels C 2   d  is a non-ejection groove which is not communicated with the nozzle hole H 2 , and is covered with an upper surface of the nozzle plate  41  from below. For example, each of the non-ejection channels C 2   d  forms the groove section penetrating the actuator plate  42 . The obverse surface  42   f   1  of the actuator plate  42  is provided with openings h 3  communicated with the respective non-ejection channels C 2   d , and the reverse surface  42   f   2  is provided with openings h 7  communicated with the respective non-ejection channels C 2   d . It is also possible for each of the non-ejection channels C 2   d  to form a groove section which does not penetrate the actuator plate  42 . 
     Here, the ejection channels C 1   e , C 2   e  each correspond to a specific example of a “channel” in the present disclosure. 
     As shown in  FIG. 3  and  FIG. 4 , the ejection channels C 1   e  and the non-ejection channels C 1   d  in the channels C 1 , and the ejection channels C 2   e  and the non-ejection channels C 2   d  in the channels C 2  are arranged in a staggered manner. Therefore, in each of the inkjet heads  4  according to the present embodiment, the ejection channels C 1   e  in the channels C 1  and the ejection channels C 2   e  in the channels C 2  are arranged in a zigzag manner. As shown in  FIG. 3  and  FIG. 4 , in the actuator plate  42 , in the park corresponding to each of the non-ejection channels C 1   d , C 2   d , there is formed a shallow groove section Dd communicated with an outside end part extending along the Y-axis direction in the non-ejection channel C 1   d , C 2   d.    
     As described later, each of the ejection channels C 1   e , C 2   e  and each of the non-ejection channels C 1   d , C 2   d  are formed by cutting the piezoelectric substrate using, for example, a dicing blade (also referred to as a diamond blade) obtained by embedding cutting abrasive grains made of diamond or the like on the outer circumference of a disk. Each of the ejection channels C 1   e , C 2   e  is formed by cutting the piezoelectric substrate from an upper surface (a surface corresponding to the upper side in the actuator plate  42 ) toward a lower surface (a surface corresponding to the lower side in the actuator plate  42 ) using, for example, the dicing blade. Each of the non-ejection channels C 1   d , C 2   d  is formed by cutting the piezoelectric substrate from the lower surface toward the upper surface using, for example, the dicing blade. 
     On this occasion, the cross-sectional shape in the longitudinal direction of each of the ejection channels C 1   e , C 2   e  is an inverted trapezoidal shape as shown in, for example,  FIG. 5  and  FIG. 6 . In contrast, the cross-sectional shape in the longitudinal direction of each of the non-ejection channels C 1   d , C 2   d  is a trapezoidal shape as shown in, for example,  FIG. 5  and  FIG. 6 . 
     In the extending direction (the Y-axis direction) of each of the ejection channels C 1   e , the length of the opening h 5  in the reverse surface  42   f   2  of the actuator plate  42  is made shorter than the length of the opening h 1  in the obverse surface  42   f   1  of the actuator plate  42  of each of the ejection channels C 1   e  as shown in, for example,  FIG. 3 ,  FIG. 4 , and  FIG. 5 . 
     In the extending direction (the Y-axis direction) of each of the ejection channels C 2   e , the length of the opening h 8  in the reverse surface  42   f   2  of the actuator plate  42  is made shorter than the length of the opening h 4  in the obverse surface  42   f   1  of the actuator plate  42  of each of the ejection channels C 2   e  as shown in, for example,  FIG. 3 ,  FIG. 4 , and  FIG. 6 . 
     Here, the openings h 1 , h 4  each correspond to a specific example of a “first opening” in the present disclosure, and the openings h 5 , h 8  each correspond to a specific example of a “second opening” in the present disclosure. 
     In the extending direction (the Y-axis direction) of each of the non-ejection channels C 1   d , the length of the opening h 6  in the reverse surface  42   f   2  of the actuator plate  42  is made longer than the length of the opening h 2  in the obverse surface  42   f   1  of the actuator plate  42  of each of the non-ejection channels C 1   d  as shown in, for example,  FIG. 3 ,  FIG. 4 , and  FIG. 6 . 
     In the extending direction (the Y-axis direction) of each of the non-ejection channels C 2   d , the length of the opening h 7  in the reverse surface  42   f   2  of the actuator plate  42  is made longer than the length of the opening h 3  in the obverse surface  42   f   1  of the actuator plate  42  of each of the non-ejection channels C 2   d  as shown in, for example,  FIG. 3 ,  FIG. 4 , and  FIG. 5 . 
     The ejection channels C 1   e  of the channel column  421  and the non-ejection channels C 2   d  of the channel column  422  are respectively arranged along the Y-axis direction as shown in, for example,  FIG. 3 ,  FIG. 4  and  FIG. 5 . In this case, a part of a tilted surface on the non-ejection channel C 2   d  side out of the pair of tilted surfaces opposed to each other in the longitudinal direction in the ejection channel C 1   e , and a part of a tilted surface on the ejection channel C 1   e  side out of the pair of tilted surfaces opposed to each other in the longitudinal direction in the non-ejection channel C 2   d  overlap each other when viewed from the thickness direction (the Z-axis direction) of the actuator plate  42 . Thus, it is possible to decrease the distance between the ejection channel C 1   e  and the non-ejection channel C 2   d  while preventing the ejection channel C 1   e  and the non-ejection channel C 2   d  from being communicated with each other. 
     Further, the non-ejection channels C 1   d  of the channel column  421  and the ejection channels C 2   e  of the channel column  422  are respectively arranged along the Y-axis direction as shown in, for example,  FIG. 3 ,  FIG. 4  and  FIG. 6 . In this case, a part of a tilted surface on the ejection channel C 2   e  side out of the pair of tilted surfaces opposed to each other in the longitudinal direction in the non-ejection channel C 1   d , and a part of a tilted surface on the non-ejection channel C 1   d  side out of the pair of tilted surfaces opposed to each other in the longitudinal direction in the ejection channel C 2   e  overlap each other when viewed from the normal direction (the Z-axis direction) of the actuator plate  42 . Thus, it is possible to decrease the distance between the non-ejection channel C 1   d  and the ejection channel C 2   e  while preventing the non-ejection channel C 1   d  and the ejection channel C 2   e  from being communicated with each other. 
     Here, as shown in  FIG. 3  through  FIG. 8 , drive electrodes Ed extending along the Y-axis direction are disposed on the inner side surfaces opposed to each other in each of the drive walls Wd described above. As the drive electrodes Ed, there exist common electrodes Edc disposed on the inner side surfaces facing the ejection channels C 1   e , C 2   e , and active electrodes Eda disposed on the inner side surfaces facing the non-ejection channels C 1   d , C 2   d . Such drive electrodes Ed (the common electrodes Edc and the active electrodes Eda) are each formed up to the same depth (the same depth in the Z-axis direction) as the drive wall Wd on the inner side surface of the drive wall Wd as shown in, for example,  FIG. 8 . The drive electrodes Ed are not necessarily required to be formed up to the same depth as the drive walls Wd in the inner side surfaces of the channels. Here, the common electrode Edc corresponds to a specific example of an “electrode” in the present disclosure. The drive electrodes Ed are each formed of a laminated film including, for example, titanium (Ti) and gold (Au) in this order from the drive wall Wd side. 
     As shown in  FIG. 7 , the common electrodes Edc each include an obverse surface side part Edc-u and a reverse surface side part Edc-d. Both of the obverse surface side part Edc-u and the reverse surface side part Edc-d extend along the Y-axis direction. The obverse surface side part Edc-u is disposed on the drive wall Wd on the opening h 1  (or the opening h 4 ) side of the obverse surface  42   f   1 , and the reverse surface side part Edc-d is disposed closer to the opening h 5  (or the opening h 8 ) of the reverse surface  42   f   2  than the obverse surface side part Edc-u. In the present embodiment, in the extending direction (the Y-axis direction) of the channels C 1 , C 2 , the size of the reverse surface side part Edc-d is made equal to the size of the obverse surface side part Edc-u, or larger than the size of the obverse surface side part Edc-u. In other words, the size in the Y-axis direction of the obverse surface side part Edc-u is equal to or smaller than the size in the Y-axis direction of the reverse surface side part Edc-d. Although the details will be described later, thus, the electrode area of the common electrode Edc decreases compared to the case ( FIG. 13  described later) of making the size of the obverse surface side part Edc-u larger than the size of the reverse surface side part Edc-d, and it becomes possible to suppress the stray capacitance. 
     For example, as shown in  FIG. 7 , the size in the Y-axis direction of the reverse surface side part Edc-d is made larger than the size in the Y-axis direction of the obverse surface side part Edc-u. It is preferable for the size in the Y-axis direction of the reverse surface side part Edc-d to be equal to the size in the Y-axis direction of the opening h 5  (or the opening h 8 ). The size in the Y-axis direction of the obverse surface side part Edc-u is made smaller than the size in the Y-axis direction of, for example, the opening h 5  (or the opening h 7 ). The reverse surface side part Edc-d is disposed so as to increase in width from the both ends in the Y-axis direction of the obverse surface side part Edc-u. Although not shown in the drawings, as described above, it is possible for the size in the Y-axis direction of the reverse surface side part Edc-d and the size in the Y-axis direction of the obverse surface side part Edc-u to be equal to each other. As described later, by making the size in the Y-axis direction of the obverse surface side part Edc-u equal to or smaller than the size of the opening h 5  (or the opening h 8 ) on the nozzle hole H 1  (or the nozzle hole H 2 ) side, the stray capacitance is reduced, and it becomes possible to suppress the variation in ejection speed caused by noise. 
     The inkjet heads  4  each have a bonding layer  46 A for fixing the nozzle plate  41  and the actuator plate  42  to each other between the nozzle plate  41  and the actuator plate  42 . The bonding layer  46 A is formed of an adhesive. In the case in which the nozzle plate  41  is formed of metal, the bonding layer  46 A prevents the electrical short circuit between the drive electrodes Ed and the nozzle plate  41 . Further, the inkjet heads  4  each have a bonding layer  46 B for fixing the actuator plate  42  and the cover plate  43  to each other between the actuator plate  42  and the cover plate  43 . The bonding layer  46 B is formed of an adhesive. In the case in which the cover plate  43  is formed of metal, the bonding layer  46 B prevents the electrical short circuit between the drive electrodes Ed and the cover plate  43 . It should be noted that in the case in which the cantilever type described above is used as the actuator plate  42 , each of the drive electrodes Ed (the common electrodes Edc and the active electrodes Eda) is not formed beyond an intermediate position in the depth direction (the Z-axis direction) in the inner side surface of the drive wall Wd. 
     The pair of common electrodes Edc opposed to each other in the same ejection channel C 1   e  (or the same ejection channel C 2   e ) are electrically connected to each other in a common terminal Tc. Further, the pair of active electrodes Eda opposed to each other in the same non-rejection channel C 1   d  (or the same non-ejection channel C 2   d ) are electrically separated from each other. In contrast, the pair of active electrodes Eda opposed to each other via the ejection channel C 1   e  (or the ejection channel C 2   e ) are electrically connected to each other in an active terminal Ta. 
     Here, on each of an end edge adjacent to the channel column  421  and an end edge adjacent to the channel column  422  in the actuator plate  42 , there is mounted a flexible printed circuit board  44  for electrically connecting the drive electrodes Ed and a control section (a control section  40  described later in the inkjet head  4 ) to each other. Interconnection patterns (not shown) provided to the flexible printed circuit boards  44  are electrically connected to the common terminals Tc and the active terminals Ta described above, Thus, it is arranged that the drive voltage is applied to each of the drive electrodes Ed from the control circuit  40  described later via the flexible printed circuit board  44 . 
     (Cover Plate  43 ) 
     As shown in  FIG. 3 , the cover plate  43  is disposed so as to close the channels C 1 , C 2  (the channel columns  421 ,  422 ) in the actuator plate  42 . Specifically, the cover plate  43  is fixed to the upper surface of the actuator plate  42  via the bonding layer  46 B, and is provided with a plate-like structure. 
     As shown in  FIG. 3 , the cover plate  43  is provided with an exit side common ink chamber  431  and a pair of entrance side common ink chambers  432 ,  433 . Specifically, the exit side common ink chamber  431  is formed in an area corresponding to the channel column  421  (the plurality of channels C 1 ) and the channel column  422  (the plurality of channels C 2 ) in the actuator plate  42 . The entrance side common ink chamber  432  is formed in an area corresponding to the channel column  421  (the plurality of channels C 1 ) in the actuator plate  42 . The entrance side common ink chamber  433  is formed in an area corresponding to the channel column  422  (the plurality of channels C 2 ) in the actuator plate  42 . 
     The exit side common ink chamber  431  is formed in the vicinity of an inner end part along the Y-axis direction in each of the channels C 1 , C 2 , and forms a groove section having a recessed shape. To the exit side common ink chamber  431 , there is coupled a discharge side flow channel (not shown) of the flow channel plate  45 , and the ink  9  is discharged via the discharge side flow channel of the flow channel plate  45 . In areas corresponding respectively to the ejection channels C 1   e , C 2   e  in the exit side common ink chamber  431 , there are respectively formed discharge slits (not shown) penetrating the cover plate  43  along the thickness direction of the cover plate  43 . 
     As shown in  FIG. 3 , the entrance side common ink chamber  432  is formed in the vicinity of an outer end part along the Y-axis direction in each of the channels C 1 , and forms a groove section having a recessed shape. To the entrance side common ink chamber  432 , there is coupled a supply side flow channel (not shown) of the flow channel plate  45 , and the ink  9  flows into the entrance side common ink chamber  432  via the supply side flow channel of the flow channel plate  45 . Similarly, the entrance side common ink chamber  433  is formed in the vicinity of an outer end part along the Y-axis direction in each of the channels C 2 , and forms a groove section having a recessed shape. To the entrance side common ink chamber  433 , there is coupled the supply side flow channel (not shown) of the flow channel plate  45 , and the ink  9  flows into the entrance side common ink chamber  433  via the supply side flow channel of the flow channel plate  45 . 
     In such a manner, the exit side common ink chamber  431  and the entrance side common ink chambers  432 ,  433  are each communicated with the ejection channels C 1   e , C 2   e  via the supply slits and the discharge slits, respectively, on the one hand, but are not communicated with the non-ejection channels C 1   d , C 2   d  on the other hand. Specifically, the non-ejection channels C 1   d , C 2   d  are closed by bottom parts of the exit side common ink chamber  431  and the entrance side common ink chambers  432 ,  433 . 
     (Flow Channel Plate  45 ) 
     As shown in  FIG. 8 , the flow channel plate  45  is disposed on the upper surface of the cover plate  43 , and has a predetermined flow channel (the supply side flow channel and the discharge side flow channel described above) through which the ink  9  flows. Further, to the flow channel in such a flow channel plate  45 , there are connected the flow channels in the circulation mechanism  5  described above so as to achieve inflow of the ink  9  to the flow channel and outflow of the ink  9  from the flow channel, respectively. It should be noted that since it is arranged that the dummy channels C 1   d , C 2   d  are closed by the bottom part of the cover plate  43  as described above, the ink  9  is supplied only to the ejection channels C 1   e , C 2   e , but does not inflow into the dummy channels C 1   d , C 2   d.    
     (Control Section  40 ) 
     Here, each of the inkjet heads  4  according to the present embodiment is also provided with the control section  40  for performing control of a variety of operations in the printer  1  as shown in  FIG. 2 . The control section  40  is arranged to control, for example, a variety of operations in the liquid feeding pumps  52   a ,  52   b  described above and so on besides a recording operation (the jet operation of the ink  9  in the inkjet head  4 ) of images, characters and so on in the printer  1 . Such a control section  40  is formed of, for example, a microcomputer having an arithmetic processing section and a storage section formed of a variety of types of memory. 
     [Method of Manufacturing Inkjet Head  4 ] 
     Then, a method of manufacturing the inkjet head  4  will be described using  FIG. 9A  through  FIG. 11B .  FIG. 9A  and  FIG. 9B  are flow charts showing an example of the method of manufacturing the inkjet head  4 , and  FIG. 10A  through  FIG. 10H  are schematic cross-sectional views for explaining the respective processes shown in  FIG. 9A  and  FIG. 9B . The cross-sectional views shown in  FIG. 10A  through  FIG. 10H  correspond to cross-sectional views (see  FIG. 8 ) along the line C-C shown in  FIG. 3 .  FIG. 11A  is a schematic plan view showing an evaporation mask formation process of the step S 3  shown in  FIG. 9A , and  FIG. 11B  is a schematic cross-sectional view corresponding thereto. Hereinafter, a process of manufacturing the actuator plate  42  will mainly be described. 
     Firstly, a piezoelectric substrate  42 Z for constituting the actuator plate  42  is prepared, and a pattern RP 1  of a resist film is formed (step S 1  in  FIG. 9A ) on an obverse surface (a surface to form the obverse surface  42   f   1  of the actuator plate  42 ) of the piezoelectric substrate  42 Z. Then, the ejection channels C 1   e , C 2   e  are provided (step S 2  in  FIG. 9A ) to the piezoelectric substrate  42 Z. Hereinafter, the steps S 1 , S 2  will be described using  FIG. 10A  and  FIG. 10B . 
       FIG. 10A  shows a preparation process of the piezoelectric substrate  42 Z. Firstly, two piezoelectric wafers (a piezoelectric wafer  42   a Z and a piezoelectric wafer  42   b Z) on which the polarization treatment has been performed in the thickness direction (the Z-axis direction) are prepared, and are stacked on one another so that the polarization directions thereof become opposite to each other. Subsequently, grinding work is performed on the piezoelectric wafer  42   a Z as needed to adjust the thickness of the piezoelectric wafer  42   a Z. The obverse surface of the piezoelectric wafer  42   a Z on this occasion becomes the obverse surface  42   f   1 . Thus, the piezoelectric substrate  42 Z is formed. 
     Then, the pattern RP 1  of the resist film is formed on the obverse surface of the piezoelectric substrate  42 Z, and then, the ejection channels C 1   e , C 2   e  are formed ( FIG. 10B ). The pattern RP 1  of the resist film functions as a mask when forming the common electrodes Edc and so on, and is formed on the obverse surface of the piezoelectric substrate  42 Z described above. It is also possible for the pattern RP 1  of the resist film to have a plurality of openings corresponding to the plurality of ejection channels C 1   e , C 2   e  at predetermined positions where the plurality of ejection channels C 1   e , C 2   e  is to be formed. It should be noted that the pattern RP 1  of the resist film can be formed of dry resist, or can also be formed of wet resist. 
     The ejection channels C 1   e , C 2   e  are formed by performing cutting work from the obverse surface of the piezoelectric substrate  42 Z using a dicing blade or the like not shown. Specifically, by digging down an exposed part which is not covered with the pattern RP 1  of the resist film out of the piezoelectric substrate  42 Z, the plurality of ejection channels C 1   e  and the plurality of ejection channels C 2   e  are formed so as to be arranged in parallel to each other at intervals in the X-axis direction, and at the same time arranged alternately. The obverse surface of the piezoelectric substrate  42 Z is provided with the openings h 1  (or the openings h 4 ). 
     After forming the ejection channels C 1   e , C 2   e , in the present embodiment, an evaporation mask DM is formed (step S 3  in  FIG. 9A ) on the obverse surface of the piezoelectric substrate  42 Z as shown in  FIG. 11A  and  FIG. 11B . The evaporation mask DM is for selectively covering the both end parts in the extending direction (the Y-axis direction) of the ejection channels C 1   e , C 2   e  (the openings h 1 , h 4 ). By forming such an evaporation mask DM in advance, a first evaporation part Edc- 1  is not formed in each of the both end parts in the Y-axis direction of the ejection channel C 1   e  in the subsequent formation process (step S 4  in  FIG. 9A ) of the first evaporation part Edc- 1 . Therefore, in the common electrode Edc, the size in the Y-axis direction of the obverse surface side part Edc-u on the opening h 1 , h 4  side becomes smaller than the size in the Y-axis direction of the reverse surface side part Edc-d (see  FIG. 7 ). 
     The evaporation mask DM is formed of a metal material such as SUS (Stainless Used Steel). The size of an area L in each of the both end parts of each of the ejection channels C 1   e , C 2   e  covered with the evaporation mask DM will be described later. 
     After forming the evaporation mask DM on the obverse surface of the piezoelectric substrate  42 Z, the first evaporation part Edc- 1  constituting a part of the common electrode Edc is formed (step S 4  in  FIG. 9A ) on the inner side surface of each of the ejection channels C 1   e , C 2   e . Then, the pattern RP 1  of the resist film is removed (step S 5  in  FIG. 9A ), Subsequently, the cover plate  43  is bonded (step S 6  in  FIG. 9A ) to the obverse surface of the piezoelectric substrate  42 Z. Hereinafter, the steps S 4 , S 5 , and S 6  will be described using  FIG. 10C  and  FIG. 10D . 
     As shown in  FIG. 10C , the first evaporation part Edc- 1  is formed of a metal coating MF 1  formed on the inner side surface of each of the ejection channels C 1   e , C 2   e . The metal coating MF 1  is formed by evaporating a conductive material on the inner side surfaces of the plurality of ejection channels C 1   e , C 2   e  and the resist pattern RP 1  from, for example, the opening h 1 , h 4  side (the obverse surface side of the piezoelectric substrate  42 Z). On this occasion, by performing oblique vapor deposition for attaching the constituent material of the metal coating MF 1  from an oblique direction (e.g., an incident angle β in  FIG. 12  described later) to the inner surfaces, the metal coating MF 1  (the first evaporation part Edc- 1 ) is formed up to a deep position of the ejection channels C 1   e , C 2   e  in the Z-axis direction. 
     Here, since the both end parts in the Y-axis direction of each of the ejection channels C 1   e , C 2   e  are covered with the evaporation mask DM as described above, the first evaporation part Edc- 1  is not formed in each of the both end parts in the Y-axis direction on the opening h 1 , h 5  side. The first evaporation part Edc- 1  is formed on the inner side in the Y-axis direction of the area L of each of the ejection channels C 1   e , C 2   e  covered with the evaporation mask DM. The first evaporation part Edc- 1  mainly constitutes the obverse surface side part Edc-u of the common electrode Edc. 
     It should be noted that it is also possible to perform a descumming treatment for removing residues such as the resist adhering to the inner side surfaces of each of the ejection surfaces C 1   e , C 2   e  as needed in an anterior stage to the formation of the metal coating MF 1 . 
     After forming the metal coating MF 1 , as shown in  FIG. 10D , the resist pattern RP 1  is removed (a liftoff method), and then, the cover plate  43  is bonded to the obverse surface of the piezoelectric substrate  42 Z using an adhesive  46 B. Here, by removing the resist pattern RP 1  only a part (the first evaporation part Edc- 1 ) covering the inner side surface of each of the ejection channels C 1   e , C 2   e  out of the metal coating MF 1  remains. 
     In the liftoff method, burrs due to the metal coating MF 1  are apt to occur. If such burrs occur frequently, a removal process of the burrs becomes necessary. The burrs due to the metal coating MF 1  are apt to occur in the both end parts in the extending direction (the Y-axis direction) of the ejection channels C 1   e , C 2   e . Here, since the first evaporation part Edc- 1  is not formed in the both end parts in the Y-axis direction on the opening h 1 , h 5  side as described above, if the first evaporation part Edc- 1  is formed using the liftoff method, the burrs due to the liftoff method are difficult to occur. Therefore, it is possible to omit the removal process of the burrs, and it becomes possible to suppress the number of processes. 
     After bonding the cover plate  43  on the obverse surface of the piezoelectric substrate  42 Z, the piezoelectric substrate  42 Z is ground (step S 7  in  FIG. 9A ) from the reverse surface side (the piezoelectric wafer  42   b Z side). 
       FIG. 10E  shows a schematic configuration of the step S 7 . As described above, the grinding work is performed on the piezoelectric wafer  42   b Z from a reverse surface (a surface on the opposite side to the piezoelectric wafer  42   a Z) to adjust the thickness of the piezoelectric wafer  42   b Z. The reverse surface of the piezoelectric wafer  42   b Z on this occasion becomes the reverse surface  42   f   2 . The grinding work is performed until the plurality of ejection channels C 1   e , C 2   e  is exposed. Thus, the openings h 5  (or the openings h 8 ) of the reverse surface  42   f   2  respectively communicated with the ejection channels C 1   e , C 2   e  are formed. Thus, a so-called chevron type actuator plate  42  is formed. 
     Here, the size of the area L in each of the both end parts of the ejection channels C 1   e , C 2   e  covered with the evaporation mask DM will be described. 
     It is preferable for the evaporation mask DM to cover the both end parts of each of the ejection channels C 1   e , C 2   e  so as to include a part where the depth Di of the first evaporation part Edc- 1  (step S 4 ) to be formed later becomes larger than the depth D of the ejection channels C 1   e , C 2   e . In other words, in the area L (see  FIG. 11B ) of the both end parts of each of the ejection channels C 1   e , C 2   e  to be covered with the evaporation mask DM, in the case in which the evaporation mask DM is not disposed, the first evaporation part Edc- 1  is formed deeper than the ejection channels C 1   e , C 2   e , and the evaporation material is attached to the bottom surfaces of the ejection channels C 1   e , C 2   e . If the evaporation material is attached to the bottom surfaces of the ejection channels C 1   e , C 2   e  in the step S 4 , the evaporation material is ground together with the piezoelectric wafer  42   b Z when performing the grinding work on the piezoelectric wafer  42   b Z from the reverse surface in the step S 7 . Thus, the burrs are formed on the reverse surface  42   f   2  of the actuator plate  42 , and the removal process of the burrs becomes necessary. 
     By covering such an area L with the evaporation mask DM, the first evaporation part Edc- 1  is not formed in the area L in the step S 4 , and therefore, it is possible to prevent the burrs from occurring in the reverse surface  42   f   2  of the actuator plate  42  in the step S 7 . Therefore, it becomes possible to omit the removal process of the burrs to suppress the number of processes. 
     As described above, it is preferable for the area L to include the part where the depth Di of the first evaporation part Edc- 1  becomes larger than the depth D of the ejection channels C 1   e , C 2   e . The depth Di of the first evaporation part Edc- 1  is expressed using, for example, the following formula (1).
 
 Di=s /tan(β−θ)− r   (1)
 
     where s: the width of the ejection channels C 1   e , C 2   e  
         β: the incident angle of the evaporation when forming the first evaporation part Edc- 1     θ: the tilt angle of the piezoelectric substrate  42 Z   r: the thickness of the resist film (the pattern RP 1 )       

       FIG. 12  schematically shows the relationship between the depth D of the ejection channels C 1   e , C 2   e  described above, the depth Di of the first evaporation part Edc- 1 , the width s of the ejection channels C 1   e , C 2   e , the incident angle β, the tilt angle θ, and the thickness r of the resist film (the pattern RP 1 ). The depth D of the ejection channels C 1   e , C 2   e  is the size in the Z-axis direction of the ejection channels C 1   e , C 2   e , and the width s of the ejection channels C 1   e , C 2   e  is the size in the X-axis direction of the ejection channels C 1   e , C 2   e . The incident angle β is an angle formed by the evaporation direction with respect to the vertical direction V, and the tilt angle θ is an angle formed by the piezoelectric substrate  42 Z with respect to the vertical direction V. The thickness r of the resist film (the pattern RP 1 ) is the size in the Z-axis direction of the resist film. 
     After providing the openings h 5  (or the openings h 8 ) of the ejection channels C 1   e , C 2   e  to the reverse surface  42   f   2  of the actuator plate  42 , a pattern RP 2  of a resist film is formed (step S 8  in  FIG. 9B ) on the reverse surface  42   f   2 . Then, the non-ejection channels C 1   d , C 2   d  are provided (step S 9  in  FIG. 9B ) to the actuator plate  42 . Hereinafter, the steps S 8 , S 9  will be described using  FIG. 10F . 
     The pattern RP 2  of the resist film to be formed on the reverse surface  42   f   2  of the actuator plate  42  functions as a mask when forming the active electrodes Eda, second evaporation parts Edc- 2  described later, and so on. It is also possible for the pattern RP 2  of the resist film to have openings corresponding to the plurality of ejection channels C 1   e , C 2   e  and the plurality of non-ejection channels C 1   d , C 2   d  at predetermined positions at which the plurality of ejection channels C 1   e , C 2   e  and the plurality of non-ejection channels C 1   d , C 2   d  are to be formed. It should be noted that the pattern RP 2  of the resist film can be formed of dry resist, or can also be formed of wet resist. 
     After forming the pattern RP 2  of the resist film on the reverse surface  42   f   2  of the actuator plate  42 , the grinding work is performed from the reverse surface  42   f   2  of the actuator plate  42  using a dicing blade or the like not shown. Thus, the non-ejection channels C 1   d , C 2   d  are formed. The reverse surface  42   f   2  of the actuator plate  42  is provided with the openings h 6  (or the openings h 7 ) of the non-ejection channels C 1   d , C 2   d , and the obverse surface  42   f   1  is provided with the openings h 2  (or the openings h 3 ). In the grinding work when forming the non-ejection channels C 1   d , C 2   d , it is also possible to penetrate the actuator plate  42  in the thickness direction, and at the same time, grind a part in the thickness direction of the cover plate  43 . 
     After providing the actuator plate  42  with the plurality of non-ejection channels C 1   d , C 2   d , the active electrodes Eda are formed on the inner side surfaces of each of the non-ejection channels C 1   d , C 2   d , and at the same time, the second evaporation parts Edc- 2  are formed on the inner side surfaces of each of the plurality of ejection channels C 1   e , C 2   e  (step S 10  in  FIG. 9B ). 
       FIG. 10G  schematically shows a configuration of the step S 10 . The second evaporation part Edc- 2  is formed of a metal coating MF 2  formed on the inner side surfaces of each of the ejection channels C 1   e , C 2   e , and the active electrode Eda is formed of the metal coating MF 2  formed on the inner side surfaces of each of the non-ejection channels C 1   d , C 2   d . The metal coating MF 2  is formed by evaporating a conductive material on the inner side surfaces of the plurality of ejection channels C 1   e , C 2   e  and the plurality of non-ejection channels C 1   d , C 2   d , and the resist pattern RP 2  from, for example, the opening h 5 , h 6 , h 7 , and h 8  side (the reverse surface  42   f   2  side). On this occasion, it is preferable to arrange that the metal coating MF 2  (the second evaporation part Edc- 2 ) has contact with the first evaporation part Edc- 1 , or a part of the metal coating MF 2  overlap a part of the first evaporation part Edc- 1 . The second evaporation part Edc- 2  mainly constitutes the reverse surface side part Edc-d of the common electrode Edc. It is also possible for a part of the reverse surface side part Edc-d to be formed of the first evaporation part Edc- 1 , or it is also possible for a part of the obverse surface side part Edc-u to be formed of the second evaporation part Edc- 2 . By forming the second evaporation part Edc- 2  after forming the first evaporation part Edc- 1 , the common electrodes Edc are formed on the inner side surfaces of each of the ejection channels C 1   e , C 2   e.    
     After forming the metal coating MF 2 , the resist pattern RP 2  is removed (step S 11  in  FIG. 9B ). By removing the resist pattern RP 2  here (the liftoff method), as shown in  FIG. 10H , a part (the second evaporation part Edc- 2 ) covering the inner side surfaces of each of the ejection channels C 1   e , C 2   e  out of the metal coating MF 2  and a part (the active electrode Eda) covering the inner side surfaces of each of the non-ejection channels C 1   d , C 2   d  are separated from each other. 
     As described above, the nozzle plate  41  is bonded to the actuator plate  42  provided with the common electrodes Edc and the active electrodes Eda using the adhesive  46 A (step S 12  in  FIG. 9B ). Further, the flow channel plate  45  is bonded to the cover plate  43 . 
     For example, in such a manner, it is possible to manufacture the inkjet head  4  according to the present embodiment. 
     [Basic Operation of Printer  1 ] 
     In the printer  1 , the recording operation (a printing operation) of images, characters, and so on to the recording paper P is performed in the following manner. It should be noted that as an initial state, it is assumed that the four types of ink tanks  3  ( 3 Y,  3 M,  3 C and  3 B) shown in  FIG. 1  are sufficiently filled with the ink  9  of the corresponding colors (the four colors), respectively. Further, there is achieved the state in which the inkjet heads  4  are filled with the ink  9  in the ink tanks  3  via the circulation mechanism  5 , respectively. 
     In such an initial state, when operating the printer  1 , the grit rollers  21  in the carrying mechanisms  2   a ,  2   b  each rotate to thereby carry the recording paper P along the carrying direction d (the X-axis direction) between the grit rollers  21  and the pinch rollers  22 . Further, at the same time as such a carrying operation, the drive motor  633  in the drive mechanism  63  rotates each of the pulleys  631   a ,  631   b  to thereby operate the endless belt  632 . Thus, the carriage  62  reciprocates along the width direction (the Y-axis direction) of the recording paper P while being guided by the guide rails  61   a ,  61   b . Then, on this occasion, the four colors of ink  9  are appropriately ejected on the recording paper P by the respective inkjet heads  4  ( 4 Y,  4 M,  4 C and  4 B) to thereby perform the recording operation of images, characters, and so on to the recording paper P. 
     [Detailed Operation in Inkjet Head  4 ] 
     Then, the detailed operation (the jet operation of the ink  9 ) in the inkjet head  4  will be described with reference to  FIG. 1  through  FIG. 8 , Specifically, in the inkjet heads  4  (the side-shoot type, the circulation type inkjet heads) according to the present embodiment, the jet operation of the ink  9  using a shear mode is performed in the following manner. 
     Firstly, when the reciprocation of the carriage  62  (see  FIG. 1 ) described above is started, a control section  40  applies the drive voltages to the drive electrodes Ed (the common electrodes Edc and the active electrodes Eda) in the inkjet head  4  via the flexible printed circuit boards  44 . Specifically, the control section  40  applies the drive voltage to the drive electrodes Ed disposed on the pair of drive walls Wd forming the ejection channel C 1   e , C 2   e . Thus, the pair of drive walls Wd each deform (see  FIG. 5 ,  FIG. 6  and  FIG. 8 ) so as to protrude toward the non-ejection channel C 1   d , C 2   d  adjacent to the ejection channel C 1   e , C 2   e.    
     As described above, due to the flexion deformation of the pair of drive walls Wd, the capacity of the ejection channel C 1   e , C 2   e  increases. Further, due to the increase in the capacity of the ejection channel C 1   e , C 2   e , it results in that the ink  9  retained in the exit side common ink chamber  431  is induced into the ejection channel C 1   e , C 2   e  (see  FIG. 3 ). 
     Subsequently, the ink  9  having been induced into the ejection channel C 1   e , C 2   e  in such a manner turns to a pressure wave to propagate to the inside of the ejection channel C 1   e , C 2   e . Then, the drive voltage to be applied to the drive electrodes Ed becomes 0 (zero) V at the timing at which the pressure wave has reached the nozzle hole H 1 , H 2  of the nozzle plate  41 . Thus, the drive walls Wd are restored from the state of the flexion deformation described above, and as a result, the capacity of the ejection channel C 1   e , C 2   e  having once increased is restored again (see  FIG. 5 ). 
     When the capacity of the ejection channel C 1   e , C 2   e  is restored in such a manner, the internal pressure of the ejection channel C 1   e , C 2   e  increases, and the ink  9  in the ejection channel C 1   e , C 2   e  is pressurized. As a result, the ink  9  having a droplet shape is ejected (see  FIG. 5 ,  FIG. 6  and  FIG. 8 ) toward the outside (toward the recording paper P) through the nozzle hole H 1 , H 2 . The jet operation (the ejection operation) of the ink  9  in the inkjet head  4  is performed in such a manner, and as a result, the recording operation of images, characters, and so on to the recording paper P is performed. In particular, the nozzle holes H 1 , H 2  of the present embodiment each have the tapered shape gradually decreasing in diameter in the downward direction (see  FIG. 5 ) as described above, and can therefore eject the ink  9  straight (good in straightness) at high speed. Therefore, it becomes possible to perform recording high in image quality. 
     [Functions and Advantages] 
     Then, the functions and the advantages of the head chip  4   c , the inkjet head  4 , and the printer  1  according to the embodiment of the present disclosure will be described. 
     In the head chip  4   c  according to the present embodiment, the common electrodes Edc each include the obverse surface side part Edc-u on the opening h 1 , h 4  side, and the reverse surface side part Edc-d on the opening h 5 , h 8  side, and the size in the Y-axis direction of the obverse surface side part Edc-u is made equal to the size in the Y-axis direction of the reverse surface side part Edc-d, or smaller than the size in the Y-axis direction of the reverse surface side part Edc-d. Thus, the increase in electrode area of the common electrode Edc can be suppressed compared to a head chip  104   c  ( FIG. 13 ) according to the following comparative example. 
       FIG. 13  shows a schematic cross-sectional configuration of a principal part of the head chip  104   c  according to the comparative example. In the head chip  104   c , although the common electrode Edc includes the obverse surface side part Edc-u on the opening h 1  side, and the reverse surface side part Edc-d on the opening h 5  side, the size in the Y-axis direction of the obverse surface side part Edc-u is made larger than the size in the Y-axis direction of the reverse surface side part Edc-d. Such an obverse surface side part Edc-u is formed by, for example, evaporating the conductive material from the opening h 1  side without providing the evaporation mask (e.g., the evaporation mask DM in  FIG. 11A  and  FIG. 11B ), and the size in the Y-axis direction of the obverse surface side part Edc-u is roughly the same as the size in the Y-axis direction of the opening h 1 . 
     Since such a common electrode Edc is large in the electrode area, the current amount and the power consumption are higher. In addition, since the amount of heat generation is also high, a failure of an electronic component such as the control section  40  is apt to be incurred. Further, the size in the Y-axis direction of the obverse surface side part Edc-u is made larger than the size in the Y-axis direction of the opening h 5  on the nozzle hole H 1  side. In other words, the common electrode Edc (the obverse surface side part Edc-u) is formed on the drive wall Wd of a part which does not make a contribution to the ejection, There is a possibility that the stray capacitance occurs due to the common electrode Edc in this part to generate an unintended drive of the drive wall Wd, namely a noise. The generation of the noise incurs a variation in ejection speed. Further, the cost increases due to gold (Au) constituting the common electrodes Edc. 
     In contrast, in the present embodiment, by disposing the evaporation mask DM in the both end parts in the Y-axis direction of the opening h 1  when evaporating the conductive material on the inner side surfaces of each of the ejection channels C 1   e , C 2   e  from, for example, the opening h 1 , h 4  side, the size in the Y-axis direction of the obverse surface side part Edc-u is made equal to the size in the Y-axis direction of the reverse surface side part Edc-d, or smaller than the size in the Y-axis direction of the reverse surface side part Edc-d. Thus, the electrode area becomes smaller compared to the head chip  104   c . Therefore, it becomes possible to suppress the increase in the current amount to suppress the power consumption. In addition, it becomes possible to reduce the amount of heat generation to keep the electronic component such as the control section  40  in good condition. Further, since the size in the Y-axis direction of the obverse surface side part Edc-u is equal to or smaller than the size in the Y-axis direction of the openings h 5 , h 8 , it is possible to suppress the generation of the noise caused by the stray capacitance. Therefore, the variation in ejection speed is reduced, and it becomes possible to improve the image quality. Further, it becomes possible to suppress the cost required for the common electrodes Edc. 
     Further, as described above, since the first evaporation part Edc- 1  is not formed in the both end parts in the Y-axis direction of each of the openings h 1 , h 4 , it becomes difficult for the burrs to occur on the reverse surface  42   f   2  of the actuator plate  42  when forming (see  FIG. 10E ) the openings h 5 , h 8  of the reverse surface  42   f   2  of the actuator plate  42 . Therefore, it becomes possible to omit the removal process of the burrs to suppress the number of processes. 
     In particular, by covering the part where the depth Di of the first evaporation part Edc- 1  becomes larger than the depth D of the ejection channels C 1   e , C 2   e , the burrs on the reverse surface  42   f   2  of the actuator plate  42  can more effectively be suppressed. 
     Further, in the head chip  4   c  according to the present embodiment, the common electrode Edc includes the first evaporation part Edc- 1  formed by the evaporation from the opening h 1 , h 4  side of the obverse surface  42   f   1 , and the second evaporation part Edc- 2  formed by the evaporation from the opening h 5 , h 8  side of the reverse surface  42   f   2 . Thus, compared to the case of forming the common electrode  42  from only either one of the obverse surface  42   f   1  side and the reverse surface  42   f   2  side, it is possible to cover the inner side surfaces (the drive walls Wd) continuously from the obverse surface  42   f   1  to the reverse surface  42   f   2  even in the case in which the plurality of ejection channels C 1   e , C 2   e  each has a high aspect ratio. Therefore, the variation in the area of the common electrode Edc to be provided to the plurality of ejection channels C 1   e , C 2   e  is reduced, and thus, it is possible to reduce the variation in ejection amount of the ink  9  and the ejection speed of the ink  9  from each of the ejection channels C 1   e , C 2   e.    
     Further, since it is arranged that the first evaporation part Edc- 1  is evaporated from the obverse surface  42   f   1  (the opening h 1 , h 4 ) side, and the second evaporation part Edc- 2  is evaporated from the reverse surface  42   f   2  (the opening h 5 , h 8 ) side, it is possible to homogenize each of the film quality of the first evaporation part Edc- 1  and the film quality of the second evaporation part Edc- 2 , and it is possible to suppress the degradation of the film quality as a whole in the common electrode Edc. 
     Further, since the variation in the area of the common electrode Edc to be formed in the plurality of ejection channels C 1   e , C 2   e  is reduced, the variation in the capacitance in the head chip  4   c  is reduced, and thus, the variation in temperature in the head chip  4   c  when ejecting the ink is reduced. As a result, the controllability by the temperature sensor is improved, and it is possible to reduce the variation in ejection amount of the ink  9  and ejection speed of the ink  9  from the ejection channels C 1   e , C 2   e.    
     As described above, in the head chip  4   c , the inkjet head  4 , and the printer  1  according to the present embodiment, since the size in the Y-axis direction of the obverse surface side part Edc-u of the common electrode Edc is made equal to the size in the Y-axis direction of the reverse surface side part Edc-d, or smaller than the size in the Y-axis direction of the reverse surface side part Edc-d, it is possible to suppress the increase in electrode area of the common electrode Edc. Therefore, it becomes possible to suppress the stray capacitance to improve the image quality. Further, it becomes possible to suppress the increase in the current amount to suppress the power consumption. Further, it becomes possible to suppress the cost required for the drive electrode Ed (the common electrodes Edc). 
     &lt;2. Modified Example&gt; 
     Then, a modified example of the embodiment described above will be described. It should be noted that substantially the same constituents as those in the embodiment are denoted by the same reference symbols, and the description thereof will arbitrarily be omitted. 
       FIG. 14  shows a schematic cross-sectional configuration of a principal part of an inkjet head  4 A according to the modified example of the embodiment described above. The inkjet head  4 A includes the nozzle plate  41 , the actuator plate  42 , the cover plate  43 , the flow channel plate  45 , and a sealing plate  48 . The inkjet head  4 A is a so-called edge-shoot type inkjet head for ejecting the ink from a tip part in the extending direction (the Z-axis direction in  FIG. 14 ) of the ejection channel C 1   e . Except this point, the configuration of the inkjet head  4 A according to the modified example is substantially the same as the configuration of the inkjet head  4  described in the above embodiment, and can exert substantially the same advantages as those of the inkjet head  4  described in the above embodiment. 
     In the inkjet head  4 A, the flow channel plate  45 , the cover plate  43 , the actuator plate  42 , and the sealing plate  48  are disposed so as to be stacked on one another in this order, and the nozzle plate  41  is disposed roughly perpendicularly to these plates. 
     On the opposed surface of the flow channel plate  45  to the cover plate  43 , there is disposed a supply side flow channel  451  to be communicated with a common ink chamber  431 . The cover plate  43  has slits  430  communicated with the common ink chamber  431  and opening on the actuator plate  42  side. The plurality of slits  430  is provided to the cover plate  43 , and is disposed at positions corresponding to the plurality of ejection channels C 1   e . The common ink chamber  431  is disposed commonly to the plurality of slits  430 , and is communicated with the ejection channels C 1   e  through the plurality of slits  430 . 
     The sealing plate  48  is opposed to the cover plate  43  across the actuator plate  42 . In other words, it is arranged that the plurality of ejection channels C 1   e  and the plurality of dummy channels C 1   d  are closed by the sealing plate  48  and the cover plate  43 . The sealing plate  48  is not required to have an opening, a cutout, a groove, or the like. In other words, since it is sufficient for the sealing plate  53  to be a simple rectangular solid, it is possible to use a functional material difficult to fabricate, or a low-price material difficult to obtain high processing accuracy as the constituent material thereof. Therefore, the degree of freedom of selection of a material type is enhanced. 
     The actuator plate  42  has the obverse surface  42   f   1  opposed to the cover plate  43 , and the reverse surface  42   f   2  opposed to the sealing plate  48 . Similarly to the embodiment described above, the size in the extending direction (the Z-axis direction) of the ejection channel C 1   e  of the opening h 1  of the obverse surface  42   f   1  is made larger than the size in the Z-axis direction of the opening h 5  of the reverse surface  42   f   2 . In the common electrode Edc disposed on the inner side surface of the ejection channel C 1   e , the size in the Z-axis direction of the obverse surface side part Edc-u on the opening h 1  side is made equal to the size in the Z-axis direction of the reverse surface side part Edc-d on the opening h 5  side, or smaller than the size in the Z-axis direction of the reverse surface side part Edc-d. For example, the obverse surface side part Edc-u and the reverse surface side part Edc-d both extend in the Z-axis direction from an end part of the ejection channel C 1   e  on the nozzle plate  41  side. In other words, the positions of the one end parts of the obverse surface side part Edc-u and the reverse surface side part Edc-d are roughly the same in the Z-axis direction. For example, the position of the other end part of the obverse surface side part Edc-u is disposed closer to the nozzle plate  41  than the position of the other end part of the reverse surface side part Edc-d in the Z-axis direction. 
     Such an edge-shoot type inkjet head  4 A can also suppress the increase in the electrode area of the common electrode Edc by making the size in the Z-axis direction of the obverse surface side part Edc-u equal to the size in the Z-axis direction of the reverse surface side part Edc-d, or smaller than the size in the Z-axis direction of the reverse surface side part Edc-d. 
     &lt;3. Other Modified Examples&gt; 
     The disclosure is described hereinabove citing the embodiment, but the disclosure is not limited to the embodiment, and a variety of modifications can be adopted. 
     For example, in the embodiment described above, the description is presented specifically citing the configuration examples (the shapes, the arrangements, the number and so on) of each of the members in the printer  1  and the inkjet heads  4 ,  4 A, but what is described in the above embodiment is not a limitation, and it is possible to adopt other shapes, arrangements, numbers and so on. Further, the values or the ranges, the magnitude relation and so on of a variety of parameters described in the above embodiment are not limited to those described in the above embodiment, but can also be other values or ranges, other magnitude relation and so on. 
     Specifically, for example, in the embodiment described above, the description is presented citing the inkjet head  4  of the two-column type (having the two nozzle columns  411 ,  412 ), but the example is not a limitation. Specifically, for example, it is also possible to adopt an inkjet head of a single-column type (having a single nozzle column), or an inkjet head of a multi-column type (having three or more nozzle columns) with three or more columns. 
     Further, for example, in the embodiment described above, there is described the case in which the nozzle columns  411 ,  412  each extend linearly along the X-axis direction, but this example is not a limitation. It is also possible to arrange that, for example, the nozzle columns  411 ,  412  each extend in an oblique direction. Further, the shape of each of the nozzle holes H 1 , H 2  is not limited to the circular shape as described in the above embodiment, but can also be, for example, a polygonal shape such as a triangular shape, an elliptical shape, or a start shape. 
     Further, for example, although the case in which the circulation type is adopted in the inkjet heads  4  is described in the above embodiment, this example is not a limitation, and it is also possible to, for example, adopt other types without the circulation in the inkjet heads  4 . 
     Further, in the above embodiment, the description is presented citing the printer  1  (the inkjet printer) as a specific example of the “liquid jet recording device” in the present disclosure, but this example is not a limitation, and it is also possible to apply the present disclosure to other devices than the inkjet printer. In other words, it is also possible to arrange to apply the “liquid jet head” (the inkjet head  4 ) and the “head chip” (the head chip  4   c ) of the present disclosure to other devices than the inkjet printer. Specifically, for example, it is also possible to arrange that the “liquid jet head” or the “head chip” of the present disclosure is applied to a device such as a facsimile or an on-demand printer. 
     Further, although the recording object of the printer  1  is the recording paper P in the embodiment and the modified example described above, the recording object of the “liquid jet recording device” according to the present disclosure is not limited to the recording paper P. It is possible to form characters and patterns by jetting the ink to a variety of materials such as cardboard, cloth, plastic or metal. Further, the recording object is not required to have a flat shape, and it is also possible to perform painting or decoration of a variety of 3D objects such as food, architectural materials such as a tile, furniture, or a vehicle. Further, it is possible to print fabric with the “liquid jet recording device” according to the present disclosure, or it is also possible to perform 3D shaping by solidifying the ink after jetted (a so-called a 3D printer). 
     Further, it is also possible to apply the variety of examples described hereinabove in arbitrary combination. 
     It should be noted that the advantages described in the specification are illustrative only but are not a limitation, and other advantages can also be provided. 
     Further, the present disclosure can also take the following configurations. 
     &lt;1&gt; 
     A head chip adapted to jet liquid comprising an actuator plate adapted to apply pressure to the liquid, wherein the actuator plate includes an obverse surface and a reverse surface; a channel extending in a predetermined direction, and having a first opening provided to the obverse surface and a second opening which is provided to the reverse surface and is shorter in length in the predetermined direction than the first opening; and an electrode having an obverse surface side part disposed on a sidewall of the channel on the first opening side, and a reverse surface side part which is disposed on the sidewall closer to the second opening than the obverse surface side part and is one of equal to and larger than the obverse surface side part in size in the predetermined direction. 
     &lt;2&gt; 
     The head chip according to &lt;1&gt;, wherein a size in the predetermined direction of the reverse surface side part is equal to a length in the predetermined direction of the second opening. 
     &lt;3&gt; 
     The head chip according to &lt;1&gt; or &lt;2&gt;, wherein a size in the predetermined direction of the obverse surface side part is smaller than the length in the predetermined direction of the second opening. 
     &lt;4&gt; 
     The head chip according to any one of &lt;1&gt; to &lt;3&gt;, further comprising a nozzle plate provided with a nozzle hole communicated with the channel. 
     &lt;5&gt; 
     A liquid jet head comprising the head chip according to any one of &lt;1&gt; to &lt;4&gt;; and a supply mechanism adapted to supply the liquid to the head chip. 
     &lt;6&gt; 
     A liquid jet recording device comprising the liquid jet head according to &lt;5&gt;; and a containing section adapted to contain the liquid. 
     &lt;7&gt; 
     A method of manufacturing a head chip having an actuator plate adapted to apply pressure to liquid so as to jet the liquid, the method comprising forming the actuator plate, the forming the actuator plate including providing a piezoelectric substrate having an obverse surface and a reverse surface with a channel which extends in a predetermined direction and has a first opening on the obverse surface; covering both end parts of the first opening in the predetermined direction with a mask; evaporating a conductive material on a sidewall of the channel from the first opening provided with the mask so as to form a first evaporation part; grinding the reverse surface of the piezoelectric substrate so as to reach the channel, to thereby form a second opening shorter in length in the predetermined direction than the first opening on the reverse surface side of the piezoelectric substrate; and evaporating the conductive material on the sidewall of the channel from the second opening so as to form a second evaporation part, to thereby form an electrode including the first evaporation part and the second evaporation part. 
     &lt;8&gt; 
     The method of manufacturing the head chip according to &lt;7&gt;, wherein the forming the actuator plate further includes forming a resist film on the obverse surface of the piezoelectric substrate after forming the channel, and the first evaporation part is formed after forming the resist film. 
     &lt;9&gt; 
     The method of manufacturing the head chip according to &lt;8&gt;, wherein the both end parts include a part where a depth Di of the first evaporation part expressed by a following formula (1) is larger than a depth D of the channel.
 
 Di=s /tan(β−θ)− r   (1)
 
     where s: a width of the channel
         β: an incident angle of the evaporation when forming the first evaporation part   θ: a tilt angle of the piezoelectric substrate   r: a thickness of the resist film
 
&lt;10&gt;
       

     The method of manufacturing the head chip according to any one of &lt;7&gt; to &lt;9&gt;, further comprising bonding a cover plate to the obverse surface of the piezoelectric substrate after forming the first evaporation part, wherein after bonding the cover plate to the obverse surface of the piezoelectric substrate, the reverse surface of the piezoelectric substrate is ground so as to form the second opening.