Patent Publication Number: US-2023136625-A1

Title: Liquid Ejecting Head And Liquid Ejecting Apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-179518, filed Nov. 2, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a liquid ejecting head and a liquid ejecting apparatus. 
     2. Related Art 
     A liquid ejecting head includes pressure chambers that store a liquid, vibration plates formed above the pressure chambers, actuators that drive the vibration plates, and a wiring member that supplies signals to the actuators (see JP-A-2021-130258, for example). The actuators include individual electrodes provided to the pressure chambers, respectively, a common electrode provided to the individual electrodes in common, and piezoelectric bodies disposed in a space between the individual electrodes and the common electrode. 
     The liquid ejecting head includes a line of nozzles and lines of pressure chambers. The line of nozzles includes nozzles arranged in a predetermined direction. Each nozzle communicates with at least one pressure chamber. The lines of pressure chambers extend in a direction of extension of the line of nozzles. The lines of pressure chambers are located away from each other in a direction intersecting with the direction of extension of the line of nozzles. 
     In the liquid ejecting head, a signal outputted from a driving circuit is supplied to the common electrode through a wiring board and common lines. The common lines extend along a first direction which is the direction of extension of the line of pressure chambers. The wiring board is electrically coupled to the common lines through common line mounting portions. A voltage supplied to the actuator located far from each common line mounting portion is lower than a voltage supplied to the actuator located close to the common line mounting portion. To be more precise, since the common line mounting portions are located at two end portions in the first direction of the common lines, there is a problem that the voltage supplied to an actuator located at a central part is lower than the voltage supplied to an actuator located on an outer side. Accordingly, when there is a large variation in voltage supplied to the actuators arranged in the first direction, it is likely that ejection of a liquid varies among the nozzles arranged in the first direction. 
     SUMMARY 
     A liquid ejecting head according to an aspect of the present disclosure includes: a line of first pressure chambers including a plurality of first pressure chambers arranged in a first direction; a line of second pressure chambers including a plurality of second pressure chambers arranged in the first direction, the line of second pressure chambers being provided at a different position from the first pressure chambers in a second direction intersecting with the first direction; a line of nozzles including a plurality of nozzles arranged in the first direction and communicating with the first pressure chambers and the second pressure chambers in common, respectively; first piezoelectric bodies provided corresponding to the plurality of first pressure chambers; first individual electrodes individually provided to the plurality of first pressure chambers and being electrically coupled to the first piezoelectric bodies; a first common electrode provided in common to the plurality of first pressure chambers and electrically coupled to the first piezoelectric bodies; second piezoelectric bodies provided corresponding to the plurality of second pressure chambers; second individual electrodes individually provided to the plurality of second pressure chambers and being electrically coupled to the second piezoelectric bodies; a second common electrode provided in common to the plurality of second pressure chambers and electrically coupled to the second piezoelectric bodies; a wiring member that supplies a voltage to the first individual electrodes, the first common electrode, the second individual electrodes, and the second common electrode; a first individual line that electrically couples the first individual electrode to the wiring member; a first common line that electrically couples the first common electrode to the wiring member; a second individual line that electrically couples the second individual electrode to the wiring member; and a second common line that electrically couples the second common electrode to the wiring member. The wiring member is electrically coupled to the first common line at a position shifted to one side in the first direction relative to a center in the first direction of the lines of first and second pressure chambers, and the wiring member is electrically coupled to the second common line at a position shifted to another side in the first direction relative to the center in the first direction of the lines of first and second pressure chambers. 
     A liquid ejecting head according to another aspect of the present disclosure includes: a line of first pressure chambers including a plurality of first pressure chambers arranged in a first direction; a line of second pressure chambers including a plurality of second pressure chambers arranged in the first direction, the line of second pressure chambers being provided at a different position from the first pressure chambers in a second direction intersecting with the first direction; a line of first nozzles including a plurality of first nozzles arranged in the first direction and communicating with the plurality of first pressure chambers, respectively; a line of second nozzles including a plurality of second nozzles arranged in the first direction and communicating with the plurality of second pressure chambers, respectively; first piezoelectric bodies provided corresponding to the plurality of first pressure chambers; first individual electrodes individually provided to the plurality of first pressure chambers and being electrically coupled to the first piezoelectric bodies; a first common electrode provided in common to the plurality of first pressure chambers and electrically coupled to the first piezoelectric bodies; second piezoelectric bodies provided corresponding to the plurality of second pressure chambers; second individual electrodes individually provided to the plurality of second pressure chambers and being electrically coupled to the second piezoelectric bodies; a second common electrode provided in common to the plurality of second pressure chambers and electrically coupled to the second piezoelectric bodies; a wiring member that supplies a voltage to the first individual electrodes, the first common electrode, the second individual electrodes, and the second common electrode; a first individual line that electrically couples the first individual electrode to the wiring member; a first common line that electrically couples the first common electrode to the wiring member; a second individual line that electrically couples the second individual electrode to the wiring member; and a second common line that electrically couples the second common electrode to the wiring member. The wiring member is electrically coupled to the first common line at a position shifted to one side in the first direction relative to a center in the first direction of the lines of first and second pressure chambers, and the wiring member is electrically coupled to the second common line at a position shifted to another side in the first direction relative to the center in the first direction of the lines of first and second pressure chambers. 
     A liquid ejecting apparatus according to still another aspect of the present disclosure includes the above-described liquid ejecting head, and a control unit that controls an operation of ejection from the liquid ejecting head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exploded perspective view illustrating a liquid ejecting head according to Embodiment 1. 
         FIG.  2    is a sectional view illustrating the liquid ejecting head, which is a diagram illustrating a section taken along the II-II line in  FIG.  1   . 
         FIG.  3    is a plan view illustrating the liquid ejecting head. 
         FIG.  4    is a sectional view illustrating a section taken along the IV-IV line in  FIG.  3   . 
         FIG.  5    is a plan view illustrating pressure chambers, individual electrodes, and COM lines. 
         FIG.  6    is a plan view illustrating a common electrode and a VBS line. 
         FIG.  7    is a sectional view illustrating a section taken along the VII-VII line in  FIG.  6   . 
         FIG.  8    is an enlarged plan view illustrating a principal part of the liquid ejecting head according to the Embodiment 1. 
         FIG.  9    is a sectional view illustrating a section taken along the IX-IX line in  FIG.  8   . 
         FIG.  10    is a sectional view illustrating part of a liquid ejecting head according to Embodiment 2. 
         FIG.  11    is an enlarged plan view illustrating a principal part of the liquid ejecting head according to the Embodiment 2. 
         FIG.  12    is an enlarged plan view illustrating a principal part of a liquid ejecting head according to Embodiment 3. 
         FIG.  13    is an enlarged plan view illustrating a principal part of a liquid ejecting head according to Embodiment 4. 
         FIG.  14    is an enlarged plan view illustrating a principal part of a liquid ejecting head according to Embodiment 5. 
         FIG.  15    is a sectional view illustrating pressure chambers on a line A side of a liquid ejecting head according to Embodiment 6. 
         FIG.  16    is a sectional view illustrating pressure chambers on a line B side of the liquid ejecting head according to the Embodiment 6. 
         FIG.  17    is a sectional view illustrating a liquid ejecting head according to Embodiment 7. 
         FIG.  18    is a schematic diagram illustrating a liquid ejecting apparatus including a liquid ejecting head. 
         FIG.  19    is a block diagram illustrating the liquid ejecting apparatus including the liquid ejecting head. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Embodiments of the present disclosure will be described below with reference to the drawings. It is to be noted, however, that dimensions and scales of components in the drawings are different from those of actual ones as needed. The embodiments described below represent specific preferred examples of the present disclosure and are therefore provided with various technically desirable limitations. Nevertheless, the scope of the present disclosure is not limited to these embodiments unless the following description expressly states the specific limitations of the present disclosure. 
     In the following description, three directions intersecting with one another may be explained as x-axis direction, y-axis direction, and z-axis direction, respectively. The x-axis direction includes x1 direction and x2 direction which are mutually opposite directions. The x-axis direction represents an example of a second direction. The y-axis direction includes y1 direction and y2 direction which are mutually opposite directions. The y-axis direction represents an example of a first direction. The z-axis direction includes z1 direction and z2 direction which are mutually opposite directions. The z1 direction represents an example of a third direction. The x-axis direction, the y-axis direction, and the z-axis direction are orthogonal to one another. Although the z-axis direction is usually a direction along an up-down direction, the z-axis direction does not always have to be the direction along the up-down direction. 
     Embodiment 1 
     A liquid ejecting head  10  according to Embodiment 1 will be described with reference to  FIGS.  1  to  8   .  FIG.  1    is an exploded perspective view illustrating the liquid ejecting head  10  according to the Embodiment 1.  FIG.  2    is a sectional view illustrating the liquid ejecting head  10 , which is a diagram illustrating a section taken along the II-II line in  FIG.  1   .  FIG.  3    is a plan view illustrating the liquid ejecting head  10 .  FIG.  4    is a sectional view illustrating a section taken along the IV-IV line in  FIG.  3   .  FIG.  5    is a plan view illustrating pressure chambers CA, individual electrodes  51 A, and COM lines  54 A.  FIG.  6    is a plan view illustrating a common electrode  52 A and a VBS line  55 A. The liquid ejecting head  10  adopts a circulation system that circulates a liquid flowing in common liquid chambers RA and RB and pressure chambers CA and CB. 
     As illustrated in  FIG.  1   , the liquid ejecting head  10  includes a line of pressure chambers CAL and a line of pressure chambers CBL. The line of pressure chambers CAL includes the pressure chambers CA arranged in the y-axis direction. The line of pressure chambers CBL includes the pressure chambers CB arranged in the y-axis direction. Each pressure chamber CA represents an example of a “first pressure chamber”. Each pressure chamber CB represents an example of a “second pressure chamber”. The line of pressure chambers CAL represents an example of a “line of first pressure chambers” and the line of pressure chambers CBL represents an example of a “line of second pressure chambers”. As illustrated in  FIGS.  1  and  3   , the line of pressure chambers CAL and the line of pressure chambers CBL are located away from each other in the x-axis direction. Although the line of pressure chambers CAL is illustrated in  FIGS.  4  to  6   , the line of pressure chambers CBL is supposed to be the same and the illustration thereof will be omitted.  FIG.  3    illustrates part of the pressure chambers CA and CB. 
     Terms “line A side” and “line B side” will be used in the present specification. The term “line A side” will be used when indicating something related to the “line of pressure chambers CAL” while the term “line B side” will indicate something related to the “line of pressure chambers CBL”. For example, a description “a piezoelectric element  50 A on the line A side” represents a piezoelectric element  50 A that changes a pressure of a liquid inside a pressure chamber CA in the line of pressure chambers CAL. A description “a VBS line  55 A on the line A side” represents a VBS line  55 A that supplies a voltage to a common electrode  52 A of the piezoelectric element  50 A. 
       FIG.  3    illustrates a center line OX that passes through the centers in the y-axis direction of the lines of pressure chambers CAL and CBL and extends in the x-axis direction. The line of pressure chambers CAL includes pressure chambers CA0, CA1, and CA2. The pressure chamber CA0 is one of the pressure chambers CA which is located at the center in the y-axis direction. The pressure chamber CA0 is the pressure chamber CA located closest to the center line OX in the y-axis direction. When the center line OX is located between two pressure chambers CA, then these pressure chambers CA are the pressure chambers CA0. 
     The pressure chamber CA1 is the pressure chamber CA among the pressure chambers CA, which is located at one end in the y-axis direction. The pressure chamber CA1 is located farthest in the y1 direction from the center line OX in the y-axis direction. The pressure chamber CA2 is the pressure chamber CA among the pressure chambers CA, which is located at another end in the y-axis direction. The pressure chamber CA2 is located farthest in the y2 direction from the center line OX in the y-axis direction. 
     The line of pressure chambers CBL includes pressure chambers CB0, CB1, and CB2. The pressure chamber CB0 is one of the pressure chambers CB which is located at the center in the y-axis direction. The pressure chamber CB0 is the pressure chamber CB located closest to the center line OX in the y-axis direction. 
     The pressure chamber CB1 is the pressure chamber CB among the pressure chambers CB, which is located at one end in the y-axis direction. The pressure chamber CB1 is located farthest in the y1 direction from the center line OX in the y-axis direction. The pressure chamber CB2 is the pressure chamber CB among the pressure chambers CB, which is located at another end in the y-axis direction. The pressure chamber CB2 is located farthest in the y2 direction from the center line OX in the y-axis direction. 
     The liquid ejecting head  10  includes a nozzle plate  21 , compliance substrates  23 , a communication plate  24 , a pressure chamber substrate  25 , a vibration plate  26 , a sealing plate  27 , and piezoelectric elements  50 A and  50 B. The liquid ejecting head  10  includes a casing  28  and a COF  60 . The COF stands for chip on film. The present embodiment will describe the liquid ejecting head  10  that ejects an ink representing an example of a liquid. However, the liquid is not limited only to the ink, so that the liquid ejecting head  10  can eject other liquids. 
     A thickness direction of each of the nozzle plate  21 , the compliance substrates  23 , the communication plate  24 , the pressure chamber substrate  25 , the vibration plate  26 , the sealing plate  27 , and the casing  28  extends in the z-axis direction. The nozzle plate  21  and the compliance substrates  23  are disposed at a bottom portion of the liquid ejecting head  10 . The communication plate  24  is disposed in the z2 direction relative to the nozzle plate  21  and the compliance substrates  23 . The pressure chamber substrate  25  is disposed in the z2 direction relative to the communication plate  24 . The vibration plate  26  is disposed in the z2 direction relative to the pressure chamber substrate  25 . The piezoelectric elements  50 A and  50 B are formed on the vibration plate  26 . The sealing plate  27  is disposed in the z2 direction relative to the vibration plate  26 . The sealing plate  27  covers the piezoelectric elements  50 . The casing  28  is disposed above the communication plate  24 . The piezoelectric elements  50 A are provided corresponding to the pressure chambers CA. The piezoelectric elements  50 B are provided corresponding to the pressure chambers CB. Each piezoelectric element  50 A may also be referred to as a “first piezoelectric element”. Each piezoelectric element  50 B may also be referred to as a “second piezoelectric element”. The “piezoelectric element  50 A” and the “piezoelectric element  50 B” may collectively be referred to as the “piezoelectric elements  50 ” when the “piezoelectric element  50 A” and the “piezoelectric element  50 B” need not be distinguished from each other. 
     Next, a description will be given of a flow channel  40  in which the ink flows. The liquid ejecting head  10  is provided with the flow channel  40  in which the ink flows. The flow channel  40  includes a supply port  42 A, a discharge port  42 B, the common liquid chambers RA and RB, relay flow channels  43 A and  43 B, the pressure chambers CA and CB, communication flow channels  45 A to  45 C, and nozzles N. 
     The flow channel  40  includes individual flow channels  41 . The individual flow channels  41  are provided corresponding to the nozzles N, respectively. The individual flow channels  41  include individual flow channels  41 A and individual flow channels  41 B. Each individual flow channel  41 A includes the relay flow channel  43 A, the pressure chamber CA, the communication flow channel  45 A, and part of the communication flow channel  45 C. The common liquid chamber RA communicates with the individual flow channels  41 A in common, and supplies the ink to the individual flow channels  41 A. The common liquid chamber RA represents an example of a common supply flow channel. Each individual flow channel  41 A is a portion of the individual flow channel  41  located upstream of the corresponding nozzle N. 
     Each individual flow channel  41 B includes the relay flow channel  43 B, the pressure chamber CB, the communication flow channel  45 B, and part of the communication flow channel  45 C. The common liquid chamber RB communicates with the individual flow channels  41 B in common. The ink is discharged from the individual flow channels  41 B to the common liquid chamber RB. The common liquid chamber RB discharges the ink from the individual flow channels  41 B. The common liquid chamber RB represents an example of a common discharge flow channel. 
     The liquid ejecting head  10  adopts a circulation system designed to circulate the ink that flows in the pressure chambers CA and CB. As illustrated in  FIG.  18   , a circulation mechanism  8  to circulate the ink is coupled to the liquid ejecting head  10 . A liquid container  2  is coupled to the circulation mechanism  8 . The circulation mechanism  8  includes a supply flow channel  81  that supplies the ink to the liquid ejecting head  10 , a collection flow channel  82  that collects the ink discharged from the liquid ejecting head  10 , and a pump  83  that transfers the ink. Each of the supply flow channel  81  and the collection flow channel  82  may be a flow channel inside a tube, for example. Each of the supply flow channel  81  and the collection flow channel  82  includes a flow channel formed from an opening, a groove, a recess, and the like. 
     The ink in the liquid container  2  is transferred by the pump  83 . The ink flows in the supply flow channel  81 , passes through the supply port  42 A, and flows into the common liquid chamber RA. A portion of the common liquid chamber RA is formed in the communication plate  24  and another portion of the common liquid chamber RA is formed in the casing  28 . The ink in the common liquid chamber RA passes through the relay flow channel  43 A, and is supplied to the pressure chamber CA. The ink in the pressure chamber CA passes through the communication flow channel  45 A and the communication flow channel  45 C, and is ejected from the nozzle N. 
     The ink not ejected from the nozzle N passes through the communication flow channel  45 C and the communication flow channel  45 B, and flows into the pressure chamber CB. The ink in the pressure chamber CB passes through the relay flow channel  43 B, and is discharged to the common liquid chamber RB. The ink in the common liquid chamber RB flows into the collection flow channel  82  through the discharge port  42 B, and is collected by the liquid container  2 . In the liquid ejecting head  10 , the ink is circulated as described above. 
     Next, a structure of the liquid ejecting head  10  will be described. The nozzle plate  21  illustrated in  FIGS.  1  and  2    is provided with the nozzles N. The nozzles N form a line of nozzles N1. The line of nozzles N1 includes the nozzles N arranged in the y-axis direction. Each nozzle N is a through hole that penetrates the nozzle plate  21  in the z-axis direction. 
     The compliance substrates  23  are disposed on two sides in the x-axis direction of the nozzle plate  21 . Each compliance substrate  23  includes a flexible film. The compliance substrates  23  constitute bottom surfaces of the common liquid chambers RA and RB. The compliance substrates  23  are deformable by receiving a pressure of the ink. The compliance substrates  23  are deformed by the pressure of the ink, so that the compliance substrates  23  can absorb a variation in pressure of the ink in the liquid ejecting head  10 . 
     The communication plate  24  is provided with portions of the common liquid chambers RA and RB, the relay flow channels  43 A and  43 B, and the communication flow channels  45 A to  45 C. The communication plate  24  is provided with through holes, grooves or recesses, and so forth. The portions of the common liquid chambers RA and RB, the relay flow channels  43 , and the communication flow channels  45  are formed by these through holes, grooves or recesses, and so forth. 
     The common liquid chambers RA and RB are elongate in the y-axis direction. The common liquid chambers RA and RB correspond to the layout of the nozzles N in the y-axis direction. As illustrated in  FIG.  2   , upper portions of the common liquid chambers RA and RB are formed in the casing  28  while lower portions of the common liquid chambers RA and RB are formed in the communication plate  24 . The lower portions of the common liquid chambers RA and RB formed in the communication plate  24  penetrate the communication plate  24  in the z-axis direction. A portion of the common liquid chamber RA close to the nozzles N is formed to a position overlapping the pressure chamber CA when viewed in the z-axis direction. Likewise, a portion of the common liquid chamber RB close to the nozzles N is formed to a position overlapping the pressure chamber CB when viewed in the z-axis direction. 
     The relay flow channel  43 A establishes communication between the pressure chamber CA and the common liquid chamber RA. The relay flow channel  43 A is provided to each of the pressure chambers CA. The relay flow channels  43 A are disposed at given intervals in the y-axis direction. The relay flow channel  43 B establishes communication between the pressure chamber CB and the common liquid chamber RB. The relay flow channel  43 B is provided to each of the pressure chambers CB. The relay flow channels  43 B are disposed at given intervals in the y-axis direction. 
     The communication flow channel  45 A communicates with the pressure chamber CA and extends in the z-axis direction. The communication flow channel  45 A is provided to each of the pressure chambers CA. The communication flow channel  45 B communicates with the pressure chamber CB and extends in the z-axis direction. The communication flow channel  45 B is provided to each of the pressure chambers CB. 
     The communication flow channels  45 A and  45 B penetrate the communication plate  24  in the z-axis direction. The communication flow channels  45 A and  45 B are located away from one another in the x-axis direction. Each communication flow channel  45 A is disposed at a position overlapping the pressure chamber CA when viewed in the z-axis direction. Each communication flow channel  45 B is disposed at a position overlapping the pressure chamber CB when viewed in the z-axis direction. Each communication flow channel  45 C extends in the x-axis direction and establishes communication between the communication flow channel  45 A and the communication flow channel  45 B. The communication flow channel  45 C is a groove which is recessed from a bottom surface of the communication plate  24 . The communication flow channel  45 C communicates with the corresponding nozzle N. The communication flow channels  45 A to  45 C are disposed at given intervals in the y-axis direction. The nozzle plate  21  is disposed in such a way as to cover the communication flow channels  45 A to  45 C from below. Each pressure chamber CA and the corresponding pressure chamber CB communicate with each other by using the communication flow channels  45 A to  45 C. 
     The pressure chamber substrate  25  is provided with the pressure chambers CA and CB. The pressure chambers CA and CB penetrate the pressure chamber substrate  25  in the z-axis direction. Each of the pressure chambers CA and CB has a predetermined volume. The pressure chambers CA and CB are located away from each other in the x-axis direction. The pressure chambers CA are provided corresponding to the nozzles N, respectively. The pressure chambers CA are disposed at given intervals in the y-axis direction. The pressure chambers CB are provided corresponding to the nozzles N, respectively. The pressure chambers CB are disposed at given intervals in the y-axis direction. As described above, the line of pressure chambers CAL includes the pressure chambers CA. The pressure chamber substrate  25  can be produced from a single-crystalline substrate of silicon, for example. The pressure chamber substrate  25  may be produced from other materials. 
       FIG.  7    is a sectional view illustrating a section taken along the VII-VII line in  FIG.  6   . As shown in  FIGS.  4  and  7   , the vibration plate  26  is disposed at an upper surface of the pressure chamber substrate  25 . The vibration plate  26  covers openings of the pressure chamber substrate  25 . Of the vibration plate  26 , portions covering the openings of the pressure chamber substrate  25  constitute upper wall surfaces of the pressure chambers CA and CB. 
     As illustrated in  FIG.  7   , the vibration plate  26  includes an elastic layer  26   a  and an insulating layer  26   b . The elastic layer  26   a  is made of silicon dioxide (SiO 2 ), for example. The insulating layer  26   b  is made of zirconium dioxide (ZrO 2 ), for example. The elastic layer  26   a  is formed on the pressure chamber substrate  25  and the insulating layer  26   b  is formed on the elastic layer  26   a.    
     The piezoelectric elements  50 A and  50 B are formed on the vibration plate  26 . The piezoelectric elements  50 A illustrated in  FIG.  6    are disposed at positions overlapping the pressure chambers CA when viewed in the z-axis direction. The piezoelectric elements  50 B are disposed at positions overlapping the pressure chambers CB when viewed in the z-axis direction. The piezoelectric elements  50 A are provided corresponding to the pressure chambers CA, respectively. The piezoelectric elements  50 B are provided corresponding to the pressure chambers CB, respectively. 
     The vibration plate  26  is driven by the piezoelectric elements  50 A and  50 B and vibrates in the z-axis direction. A portion of the vibration plate  26  constituting the upper wall surface of each pressure chamber CA is driven by the piezoelectric element  50 A above the pressure chamber CA. A portion of the vibration plate  26  constituting the upper wall surface of each pressure chamber CB is driven by the piezoelectric element  50 B above the pressure chamber CB. A total thickness of the vibration plate  26  is equal to or below 2 μm, for example. The total thickness of the vibration plate  26  may be equal to or below 15 μm, or equal to or below 40 μm, or equal to or below 100 μm. When the total thickness of the vibration plate  26  is equal to or below 15 μm, for example, the vibration plate  26  may include a resin layer. The vibration plate  26  may be formed from a metal. Examples of the metal include stainless steel, nickel, and the like. When the vibration plate  26  is made of the metal, a plate thickness of the vibration plate  26  may be equal to or above 15 μm and equal to or below 100 μm. 
     As illustrated in  FIGS.  4  and  7   , each piezoelectric element  50 A includes the individual electrode  51 A, the common electrode  52 A, and a piezoelectric layer  53 A. Each piezoelectric element  50 B includes an individual electrode  51 B, a common electrode  52 B, and a piezoelectric layer  53 B. Since the piezoelectric elements  50 A and  50 B have the same structure, the piezoelectric element  50 A will be mainly described below. Explanations of the piezoelectric element  50 B may be omitted as appropriate. 
     The individual electrode  51 A, the piezoelectric layer  53 A, and the common electrode  52 A are stacked in this order on the vibration plate  26 . The piezoelectric layer  53 A is interposed between the individual electrode  51 A and the common electrode  52 A. The individual electrode  51 A is formed into an elongate shape that extends in the x-axis direction. The individual electrodes  51 A are arranged in the y-axis direction at intervals in between. The individual electrodes  51 A are disposed corresponding to the pressure chambers CA, respectively. As illustrated in  FIGS.  5  and  6   , the pressure chambers CA are provided with the individual electrodes  51 A, respectively. Likewise, the pressure chambers CB are provided with the individual electrodes  51 B, respectively. The individual electrodes  51 A are disposed at positions overlapping the pressure chambers CA when viewed in the z-axis direction, respectively. The individual electrodes  51 B are disposed at positions overlapping the pressure chambers CB when viewed in the z-axis direction, respectively. 
     Each of the common electrodes  52 A and  52 B takes on a strip shape and extends in the y-axis direction. The common electrode  52 A is continuously provided in such a way as to cover the individual electrodes  51 A. The common electrode  52 B is continuously provided in such a way as to cover the individual electrodes  51 B. 
     Each of the individual electrodes  51 A and  51 B includes a foundation layer and an electrode layer. The foundation layer includes titanium (Ti), for example. The electrode layer includes a low-resistance conductive material such as platinum (Pt) and iridium (Ir). The electrode layer may be formed from an oxide such as strontium ruthenate (SrRuO 3 ) and lanthanum nickel oxide (LaNiO 3 ). Each of the piezoelectric layers  53 A and  53 B is formed from a publicly known piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O 3 ) and ceramics. 
     Each of the common electrodes  52 A and the  52 B includes a foundation layer and an electrode layer. The foundation layer includes titanium, for example. The electrode layer includes a low-resistance conductive material such as platinum and Iridium. The electrode layer may be formed from an oxide such as strontium ruthenate and lanthanum nickel oxide. A region of the piezoelectric layer  53 A located between the individual electrode  51 A and the common electrode  52 A serves as a driving region. A region of the piezoelectric layer  53 B located between the individual electrode  51 B and the common electrode  52 B serves as a driving region. The driving regions are formed on the pressure chambers CA and CB, respectively. 
     A prescribed reference voltage is applied to the common electrodes  52 A and  52 B. The reference voltage is a constant voltage which is set to a voltage higher than a ground voltage, for example. A retention signal at a constant voltage is applied to the common electrodes  52 A and  52 B, for example. Driving signals at variable voltages are applied to the individual electrodes  51 A and  51 B. A voltage corresponding to a difference between the reference voltage to be applied to the common electrode  52 A and the driving signal to be applied to the individual electrode  51 A is applied to the piezoelectric layer  53 A. Likewise, a voltage corresponding to a difference between the reference voltage to be applied to the common electrode  52 B and the driving signal to be applied to the individual electrode  51 B is applied to the piezoelectric layer  53 B. The driving signal corresponds to an amount of ejection of the liquid to be ejected from the nozzle N. 
     As a consequence of deformation of the piezoelectric layer  53 A along with the application of the voltage between the individual electrode  51 A and the common electrode  52 A, the piezoelectric element  50 A creates energy for flexurally deforming the vibration plate  26 . Likewise, as a consequence of deformation of the piezoelectric layer  53 B along with the application of the voltage between the individual electrode  51 B and the common electrode  52 B, the piezoelectric element  50 B creates energy for flexurally deforming the vibration plate  26 . 
     The vibration of the vibration plate  26  with the energy generated by the piezoelectric element  50 A changes the pressure of the liquid in the pressure chamber CA, whereby the liquid in the pressure chamber CA is ejected from the nozzle N. The vibration of the vibration plate  26  with the energy generated by the piezoelectric element  50 B changes the pressure of the liquid in the pressure chamber CB, whereby the liquid in the pressure chamber CB is ejected from the nozzle N. 
     The sealing plate  27  is formed into a rectangular shape when viewed in the z-axis direction. The sealing plate  27  protects the piezoelectric elements  50 A and  50 B and reinforces mechanical strengths of the pressure chamber substrate  25  and the vibration plate  26 . The sealing plate  27  is attached to the vibration plate  26  by using an adhesive, for example. The sealing plate  27  is fixed to the pressure chamber substrate  25  through the vibration plate  26 . 
     As illustrated in  FIGS.  1  and  2   , the COF  60  includes a flexible wiring board  61  and a driving circuit  62 . The flexible wiring board  61  is a wiring board having flexibility. The flexible wiring board  61  is an FPC, for example. The flexible wiring board  61  may be an FFC, for instance. The FPC stands for flexible printed circuit. The FFC stands for flexible flat cable. 
     As illustrated in  FIG.  2   , the flexible wiring board  61  is electrically coupled to the individual electrodes  51 A and  51 B of the piezoelectric elements  50 A and  50 B through COM lines  54 A and  54 B to be described later. In the meantime, the flexible wiring board  61  is electrically coupled to the common electrodes  52 A and  52 B of the piezoelectric elements  50 A and  50 B through VBS lines  55 A and  55 B to be described later. The flexible wiring board  61  is electrically coupled to a not-illustrated circuit board. The circuit board includes a driving signal generation circuit  32  illustrated in  FIG.  19   . 
     The driving circuit  62  is mounted on the flexible wiring board  61 . The driving circuit  62  includes a switching element for driving the piezoelectric elements  50 . The driving circuit  62  is electrically coupled to a control unit  30  illustrated in  FIG.  19    through the flexible wiring board  61  and the circuit board. The driving circuit  62  receives a driving signal Com outputted from the driving signal generation circuit  32 . The switching element of the driving circuit  62  switches whether or not to supply the driving signal Com generated by the driving signal generation circuit  32  to the piezoelectric elements  50 A and  50 B. The driving circuit  62  causes the vibration plate  26  to vibrate by supplying a driving voltage or a current to the piezoelectric elements  50 A and  50 B. 
     As illustrated in  FIGS.  6  and  7   , the liquid ejecting head  10  includes the COM lines  54 A and  54 B. The COM lines  54 A are electrically coupled to the piezoelectric elements  50 A. The COM lines  54 B are electrically coupled to the piezoelectric elements  50 B. The COM lines  54 A are coupled to the individual electrodes  51 A, respectively. The COM lines  54 B are coupled to the individual electrodes  51 B, respectively. The individual electrodes  51 A are disposed in a region where the line of pressure chambers CAL is formed when viewed in the z-axis direction. The individual electrodes  51 B are disposed in a region where the line of pressure chambers CBL is formed when viewed in the z-axis direction. Since the COM lines  54 A and  54 B have the same structure, the COM lines  54 A will be mainly described below and explanations of the COM lines  54 B may be omitted as appropriate. 
     The COM lines  54 A and  54 B extend in the x-axis direction and are drawn into an opening  27   a  in the sealing plate  27 . The opening  27   a  is illustrated in  FIGS.  1  and  2   . Illustration of the COM lines  54 A and  54 B is omitted in  FIG.  1   . The opening  27   a  penetrates the sealing plate  27  in the z-axis direction. The COM lines  54 A and  54 B are electrically coupled to the COF  60  at a position corresponding to the opening  27   a  when viewed in the z-axis direction. The COM lines  54 A and  54 B are made of a conductive material having lower resistance than that of the individual electrodes  51 A and  51 B. For example, the COM lines  54 A and  54 B are conductive patterns having a structure of laminating a gold (Au) conductive film on a surface of a conductive film made of nichrome (NiCr). 
     Each of the COM lines  54 A and  54 B includes an electrode layer  54   a , a first close contact layer  54   b , and a first wiring layer  54   c . The electrode layer  54   a  covers an end surface in the x2 direction of the piezoelectric layer  53 A. The end surface in the x2 direction forms a surface intersecting with the x-axis direction. The first close contact layer  54   b  covers the electrode layer  54   a  and the individual electrode  51 . The first close contact layer  54   b  comes into close contact with the electrode layer  54   a  and the individual electrode  51 . The first wiring layer  54   c  covers the first close contact layer  54   b . The first wiring layer  54   c  is electrically coupled to the individual electrode  51  through the first close contact layer  54   b.    
       FIG.  8    is an enlarged plan view illustrating a principal part of the liquid ejecting head  10  according to the Embodiment 1. The COM lines  54 A and  54 B are electrically coupled to the flexible wiring board  61  through a COF mounting portion  64  illustrated in  FIGS.  3  and  8   . The COF mounting portion  64  includes a conductive layer that electrically couples the first wiring layer  54   c  to a wiring portion of the flexible wiring board  61 . Each individual electrode  51 A is electrically coupled to the driving circuit  62  through the COM line  54 A, the COF mounting portion  64 , and the flexible wiring board  61 . Each individual electrode  51 B is electrically coupled to the driving circuit  62  through the COM line  54 B, the COF mounting portion  64 , and the flexible wiring board  61 . 
     As illustrated in  FIGS.  3  and  8   , the liquid ejecting head  10  includes the VBS lines  55 A and  55 B as well as VBS line mounting portions  56 A and  56 B. The VBS line  55 A is electrically coupled to the common electrode  52 A. The VBS line  55 B is electrically coupled to the common electrode  52 B. The VBS line  55 A is electrically coupled to the COF  60  through the VBS line mounting portion  56 A. The VBS line  55 B is electrically coupled to the COF  60  through the VBS line mounting portion  56 B. The VBS line  55 A represents an example of a “first common line”. The VBS line  55 B represents an example of a “second common line”. 
     As illustrated in  FIG.  7   , the VBS line  55 A is located away from the COM line  54 A in the x-axis direction. An insulative adhesive  59  is provided between the VBS line  55 A and the COM line  54 A. The sealing plate  27  is attached to the VBS lines  55 A and  55 B, the piezoelectric layers  53 A and  53 B, the COM lines  54 A, and the like by using the adhesive  59 . 
     As illustrated in  FIG.  8   , the VBS line  55 A includes a first portion  57 A that extends in the y-axis direction, and a second portion  58 A that protrudes in the x-axis direction from a first end portion  57   c  of the first portion  57 A. The first portion  57 A is provided in such a way as to cover the line of pressure chambers CAL when viewed in the z-axis direction. The first portion  57 A extends to outside of the line of pressure chambers CAL in the y-axis direction. A length of the first portion  57 A is longer than a length of the line of pressure chambers CAL in the y-axis direction. 
     The first portion  57 A includes the first end portion  57   c  and a second end portion  57   d . The first end portion  57   c  is an end portion in the y1 direction and the second end portion  57   d  is an end portion in the y2 direction. The first end portion  57   c  is located in the y1 direction relative to the line of pressure chambers CAL. The second end portion  57   d  is located in the y2 direction relative to the line of pressure chambers CAL. The common electrode  52 A is formed below the first portion  57 A in the z-axis direction. The VBS line  55 A is disposed in such a way as to cover the common electrode  52 A in the y-axis direction. The VBS line  55 A is longer than the common electrode  52 A in the y-axis direction. The VBS line  55 A may be shorter than the common electrode  52 A in the y-axis direction. 
     The second portion  58 A extends in the x2 direction from the first end portion  57   c  of the first portion  57 A. The second portion  58 A is located in the y1 direction relative to the COF mounting portion  64  when viewed in the z-axis direction. The VBS line  55 A is not electrically coupled to the COF mounting portion  64 . 
       FIG.  9    is a sectional view illustrating a section taken along the IX-IX line in  FIG.  8   .  FIG.  9    is a sectional view illustrating the second portion  58 A of the VBS line  55 A, the VBS line mounting portion  56 A, and the COF  60 . As illustrated in  FIGS.  8  and  9   , the VBS line mounting portion  56 A is formed on the second portion  58 A of the VBS line  55 A. The VBS line mounting portion  56 A includes a conductive layer. The flexible wiring board  61  is electrically coupled to the VBS line mounting portion  56 A. 
     As illustrated in  FIG.  8   , the VBS line  55 B includes a first portion  57 B that extends in the y-axis direction, and a second portion  58 B that protrudes in the x-axis direction from a second end portion  57   f  of the first portion  57 B. The first portion  57 B is provided in such a way as to cover the line of pressure chambers CBL when viewed in the z-axis direction. The first portion  57 B extends to outside of the line of pressure chambers CBL in the y-axis direction. A length of the first portion  57 B is longer than a length of the line of pressure chambers CBL in the y-axis direction. 
     The first portion  57 B includes a first end portion  57   e  and the second end portion  57   f . The first end portion  57   e  is an end portion in the y1 direction and the second end portion  57   f  is an end portion in the y2 direction. The first end portion  57   e  is located in the y1 direction relative to the line of pressure chambers CBL. The second end portion  57   f  is located in the y2 direction relative to the line of pressure chambers CBL. The common electrode  52 B is formed below the first portion  57 B in the z-axis direction. The VBS line  55 B is disposed in such a way as to cover the common electrode  52 B in the y-axis direction. The VBS line  55 B is longer than the common electrode  52 B in the y-axis direction. The VBS line  55 B may be shorter than the common electrode  52 B in the y-axis direction. 
     The second portion  58 B extends in the x1 direction from the second end portion  57   f  of the first portion  57 B. The second portion  58 B is disposed in the y2 direction relative to the COF mounting portion  64  when viewed in the z-axis direction. The VBS line  55 B is not electrically coupled to the COF mounting portion  64 . 
     As illustrated in  FIG.  8   , the VBS line mounting portion  56 B is formed on the second portion  58 B of the VBS line  55 B. The VBS line mounting portion  56 B includes a conductive layer. The flexible wiring board  61  is electrically coupled to the VBS line mounting portion  56 B. 
     According to the above-described liquid ejecting head  10 , the VBS line  55 A electrically coupled to the common electrode  52 A of the line of pressure chambers CAL is electrically coupled to the COF  60  through the VBS line mounting portion  56 A. The VBS line  55 B electrically coupled to the common electrode  52 B of the line of pressure chambers CBL is electrically coupled to the COF  60  through the VBS line mounting portion  56 B. The VBS line mounting portion  56 A is disposed in the y1 direction relative to the lines of pressure chambers CAL and CBL in the y-axis direction, and the VBS line mounting portion  56 B is disposed in the y2 direction relative to the lines of pressure chambers CAL and CBL in the y-axis direction. 
     In the liquid ejecting head  10 , the VBS line mounting portions  56 A and  56 B are disposed on mutually opposite sides in the y-axis direction. Of the piezoelectric elements  50 A corresponding to the line of pressure chambers CAL, the voltage to be supplied to the common electrode  52 A of a piezoelectric element  50 A 1  located closest to the VBS line mounting portion  56 A is the highest while the voltage to be supplied to the common electrode  52 A of a piezoelectric element  50 A 2  located farthest from the VBS line mounting portion  56 A is the lowest. This phenomenon is attributed to an effect of a voltage drop due to electric resistance of the VBS line  55 A. The piezoelectric element  50 A 1  and the piezoelectric element  50 A 2  are included in the piezoelectric elements  50 A. 
     Of the piezoelectric elements  50 B corresponding to the line of pressure chambers CBL, the voltage to be supplied to the common electrode  52 B of a piezoelectric element  50 B 2  located closest to the VBS line mounting portion  56 B is the highest while the voltage to be supplied to the common electrode  52 B of a piezoelectric element  50 B 1  located farthest from the VBS line mounting portion  56 B is the lowest. This phenomenon is attributed to an effect of a voltage drop due to electric resistance of the VBS line  55 B. The piezoelectric element  50 B 1  and the piezoelectric element  50 B 2  are included in the piezoelectric elements  50 B. 
     A pressure chamber CA1 out of the pressure chambers CA which is located at the farthest end in the y1 direction and a pressure chamber CB1 out of the pressure chambers CB which is located at the farthest end in the y1 direction communicate with a common nozzle N. The liquids in the pressure chambers CA1 and CB1 are ejected from the same nozzle N. 
     A pressure chamber CA2 out of the pressure chambers CA which is located at the farthest end in the y2 direction and a pressure chamber CB2 out of the pressure chambers CB which is located at the farthest end in the y2 direction communicate with a common nozzle N. The liquids in the pressure chambers CA2 and CB2 are ejected from the same nozzle N. The liquids in the pressure chambers CA and CB which is present at the same position in the Y-axis direction are ejected from the same nozzle N. 
     Problem of Related Art 
     Next, a problem of the related art will be discussed. In the related art, the VBS line mounting portions are disposed at two end portions in the y-axis direction. In the related art, the voltage is supplied to the VBS lines coupled to the piezoelectric elements  50 A of the line of pressure chambers CAL and the VBS lines coupled to the piezoelectric elements  50 B of the line of pressure chambers CBL through the common VBS line mounting portion. As a consequence, the voltage supplied to the piezoelectric element  50  on an outer side in the y-axis direction being close to the VBS line mounting portion is higher and the voltage supplied to the piezoelectric element  50  at a central part being far from the VBS line mounting portion is lower. 
     The above-described related art is cumulatively affected by the voltage drops, thereby causing a problem of a large variation between ejection of the liquid from the nozzle N communicating with the pressure chambers CA and CB located on the outer side in the y-axis direction being close to the VBS line mounting portion and ejection of the liquid from the nozzle N communicating with the pressure chambers CA and CB located at the central part being far from the VBS line mounting portion. 
     Effects of Embodiment 1 
     As described above, in the liquid ejecting head  10  according to the Embodiment 1, the VBS line mounting portion  56 A on the line A side and the VBS line mounting portion  56 B on the line B side are disposed on mutually opposite sides in the y-axis direction. The voltage is supplied in mutually opposite directions to the VBS line  55 A on the line A side and to the VBS line  55 B on the line B side. For example, to the pressure chamber CA1 disposed at the end in the y1 direction, the voltage is supplied from the VBS line mounting portion  56 A on the close side through the VBS line  55 A. To the pressure chamber CB1 disposed at the end in the y1 direction, the voltage is supplied from the VBS line mounting portion  56 B on the far side through the VBS line  55 B. In this case, the voltage drop by the VBS line  55 A is smaller than the voltage drop by the VBS line  55 B. The effects of the voltage drops based on distances from the VBS line mounting portions  56 A and  56 B are cancelled between the piezoelectric element  50 A on the line A side and the piezoelectric element  50 B on the line B side. Accordingly, the variation in ejection of the liquid between the nozzles N is suppressed. As a consequence, reliability of the liquid ejecting head  10  is improved. 
     Embodiment 2 
     Next, a liquid ejecting head  10 B according to Embodiment 2 will be described with reference to  FIGS.  10  and  11   .  FIG.  10    is a sectional view illustrating part of the liquid ejecting head  10 B according to the Embodiment 2.  FIG.  11    is an enlarged plan view illustrating a principal part of the liquid ejecting head  10 B according to the Embodiment 2. The liquid ejecting head  10 B according to the Embodiment 2 is different from the liquid ejecting head  10  according to the Embodiment 1 in that the liquid ejecting head  10 B includes VBS lines  121 A and  122 A instead of the VBS line  55 A on the line A side, includes VBS lines  121 B and  122 B instead of the VBS line  55 B on the line B side, includes VBS line mounting portions  56 A and  127 A as the VBS line mounting portions on the line A side, and includes VBS line mounting portions  56 B and  127 B as the VBS line mounting portions on the line B side. In the description of the Embodiment 2, explanations of the same features as those in the Embodiment 1 may be omitted as appropriate. The VBS line  121 A represents an example of the “first common line”. The VBS line  121 B represents an example of the “second common line”. The VBS line  122 A represents an example of a “third common line”. The VBS line  122 B represents an example of a “fourth common line”. 
     As illustrated in  FIG.  11   , the liquid ejecting head  10 B includes the VBS lines  121 A and  122 A on the line A side, and the VBS lines  121 B and  122 B on the line B side. The VBS lines  121 A and  122 A are electrically coupled to the common electrode  52 A on the line A side. The VBS lines  121 B and  122 B are electrically coupled to the common electrode  52 B on the line B side. 
     The VBS line  121 A includes a first portion  123 A that extends in the y-axis direction, and a second portion  124 A that protrudes in the x-axis direction from an end portion  123   c  of the first portion  123 A. The VBS line  122 A includes a first portion  125 A that extends in the y-axis direction, and a second portion  126 A that protrudes in the x-axis direction from an end portion  125   d  of the first portion  125 A. The end portion  123   c  is an end portion located close to the pressure chamber CA1 in the y-axis direction and the end portion  125   d  is an end portion located close to the pressure chamber CA2 in the y-axis direction. 
     The first portion  123 A of the VBS line  121 A and the first portion  125 A of the VBS line  122 A are located away from each other in the x-axis direction. The first portion  123 A is disposed at a position farther in the x-axis direction from the COF  60  than from the first portion  125 A. In other words, the first portion  125 A is disposed at a position closer in the x-axis direction to the line of pressure chambers CBL than to the first portion  123 A. A close side to the COF  60  in the x-axis direction may be described as an “inner side” while a far side from the COF  60  may be described as an “outer side” as appropriate. The VBS line  121 A may be described as the “VBS line  121 A on the outer side” while the VBS line  122 A may be described as the “VBS line  122 A on the inner side” as appropriate. 
     As illustrated in  FIG.  10   , the first portion  125 A of the VBS line  122 A on the inner side is electrically coupled to the common electrode  52 A at a position closer in the x-axis direction to the COF  60  than to the first portion  123 A of the VBS line  121 A on the outer side. 
     The VBS line  121 B includes a first portion  123 B that extends in the y-axis direction, and a second portion  124 B that protrudes in the x-axis direction from an end portion  123   f  of the first portion  123 B. The VBS line  122 B includes a first portion  125 B that extends in the y-axis direction, and a second portion  126 B that protrudes in the x-axis direction from an end portion  125   e  of the first portion  125 B. The end portion  123   f  is an end portion located close to the pressure chamber CB2 in the y-axis direction and the end portion  125   e  is an end portion located close to the pressure chamber CB1 in the y-axis direction. 
     The first portion  123 B of the VBS line  121 B and the first portion  125 B of the VBS line  122 B are located away from each other in the x-axis direction. The first portion  123 B is disposed at a position farther in the x-axis direction from the COF  60  than from the first portion  125 B. In other words, the first portion  125 B is disposed at a position closer in the x-axis direction to the line of pressure chambers CAL than to the first portion  123 B. The VBS line  121 B may be described as the “VBS line  121 B on the outer side” while the VBS line  122 B may be described as the “VBS line  122 B on the inner side” as appropriate. 
     As illustrated in  FIG.  10   , the first portion  125 B of the VBS line  122 B on the inner side is electrically coupled to the common electrode  52 B at a position closer in the x-axis direction to the COF  60  than to the first portion  123 B of the VBS line  121 B on the outer side. 
     As illustrated in  FIG.  11   , the liquid ejecting head  10 B includes the VBS line mounting portions  56 A and  127 A on the line A side, and the VBS line mounting portions  56 B and  127 B on the line B side. The VBS line mounting portion  56 A is disposed in the y1 direction relative to the line of pressure chambers CAL on the line A side. The VBS line mounting portion  56 A is electrically coupled to the VBS line  121 A on the outer side. The VBS line mounting portion  56 A is provided at the second portion  124 A. The VBS line mounting portion  127 A is disposed in the y2 direction relative to the line of pressure chambers CAL on the line A side. The VBS line mounting portion  127 A is electrically coupled to the VBS line  122 A on the inner side. The VBS line mounting portion  127 A is provided at the second portion  126 A. 
     The VBS line mounting portion  56 B is disposed in the y2 direction relative to the line of pressure chambers CBL on the line B side. The VBS line mounting portion  56 B is electrically coupled to the VBS line  121 B on the outer side. The VBS line mounting portion  56 B is provided at the second portion  124 B. The VBS line mounting portion  127 B is disposed in the y1 direction relative to the line of pressure chambers CBL on the line B side. The VBS line mounting portion  127 B is electrically coupled to the VBS line  122 B on the inner side. The VBS line mounting portion  127 B is provided at the second portion  126 B. 
     In the liquid ejecting head  10 B according to the Embodiment 2, the VBS lines  121 A and  122 A are electrically coupled to the common electrode  52 A on the line A side. The VBS line  121 A is electrically coupled to the COF  60  on one side while the VBS line  122 A is electrically coupled to the COF  60  on another side. The voltage is supplied to the common electrode  52 A through the VBS line mounting portions  56 A and  127 A which are disposed on mutually opposite sides in the y-axis direction. In the liquid ejecting head  10 B, the VBS lines  121 B and  122 B are electrically coupled to the common electrode  52 B on the line B side. The VBS line  121 B is electrically coupled to the COF  60  on one side while the VBS line  122 B is electrically coupled to the COF  60  on another side. The voltage is supplied to the common electrode  52 B through the VBS line mounting portions  56 B and  127 B which are disposed on mutually opposite sides in the y-axis direction. Accordingly, the effects of the voltage drops on the common electrodes  52 A and  52 B are relaxed. Thus, the variation in ejection of the liquid between the nozzles N arranged in the y-axis direction is suppressed. 
     Embodiment 3 
     Next, a liquid ejecting head  10 C according to Embodiment 3 will be described with reference to  FIG.  12   .  FIG.  12    is an enlarged plan view illustrating a principal part of the liquid ejecting head according to the Embodiment 3. The liquid ejecting head  10 C according to the Embodiment 3 is different from the liquid ejecting head  10  according to the Embodiment 1 in that the liquid ejecting head  10 C includes VBS lines  131 A and  132 A instead of the VBS line  55 A on the line A side, includes VBS lines  131 B and  132 B instead of the VBS line  55 B on the line B side, includes a joining portion  133  that joins the VBS line  131 A to the VBS line  131 B, includes a joining portion  134  that joins the VBS line  132 A to the VBS line  132 B, includes a VBS line mounting portion  136  provided to the joining portion  133 , and includes a VBS line mounting portion  137  provided to the joining portion  134 . In the description of the Embodiment 3, the same explanations as those in the Embodiments 1 and 2 may be omitted as appropriate. The VBS line  131 A represents an example of the “first common line”. The VBS line  132 B represents an example of the “second common line”. The VBS line  132 A represents an example of the “third common line”. The VBS line  131 B represents an example of the “fourth common line”. 
     The liquid ejecting head  10 C includes the VBS lines  131 A and  132 A on the line A side, and the VBS lines  131 B and  132 B on the line B side. The VBS lines  131 A and  132 A are electrically coupled to the common electrode  52 A on the line A side. The VBS lines  131 B and  132 B are electrically coupled to the common electrode  52 B on the line B side. 
     The VBS lines  131 A and  132 A extend in the y-axis direction and are located away from each other in the x-axis direction. The VBS line  132 A is disposed at a position closer in the x-axis direction to the COF  60  than to the VBS line  131 A. The VBS line  131 A protrudes in the y1 direction relative to the line of pressure chambers CAL. An end portion  131   c  of the VBS line  131 A is located in the y1 direction relative to the line of pressure chambers CAL. The VBS line  132 A protrudes in the y2 direction relative to the line of pressure chambers CAL. An end portion  132   d  of the VBS line  132 A is located in the y2 direction relative to the line of pressure chambers CAL. 
     The VBS lines  131 B and  132 B extend in the y-axis direction and are located away from each other in the x-axis direction. The VBS line  132 B is disposed at a position closer in the x-axis direction to the COF  60  than to the VBS line  131 B. The VBS line  131 B protrudes in the y1 direction relative to the line of pressure chambers CBL. An end portion  131   e  of the VBS line  131 B is located in the y1 direction relative to the line of pressure chambers CBL. The VBS line  132 B protrudes in the y2 direction relative to the line of pressure chambers CBL. An end portion  132   f  of the VBS line  132 B is located in the y2 direction relative to the line of pressure chambers CBL. 
     As described above, the liquid ejecting head  10 C includes the joining portions  133  and  134 , and the VBS line mounting portions  136  and  137 . The joining portion  133  extends in the x-axis direction and joins the end portions  131   c  and  131   e  of the VBS lines  131 A and  131 B to each other. The joining portion  133  joins the VBS lines  131 A and  131 B on the outer side in the x-axis direction to each other. The joining portion  133  is located in the y1 direction relative to the lines of pressure chambers CAL and CBL. The joining portion  133  is provided with the VBS line mounting portion  136 . The VBS lines  131 A and  131 B are electrically coupled to the COF  60  through the VBS line mounting portion  136  and the joining portion  133 . The VBS lines  131 A and  131 B are electrically coupled to the COF  60  at a position on one side relative to the lines of pressure chambers CAL and CBL. The “position on one side” includes a position shifted in the y1 direction from the center line OX in the y-axis direction. A “position on another side” to be described later includes a position shifted in the y2 direction from the center line OX in the y-axis direction. 
     The joining portion  134  extends in the x-axis direction and joins the end portions  132   d  and  132   f  of the VBS lines  132 A and  132 B to each other. The joining portion  134  is located in the y2 direction relative to the lines of pressure chambers CAL and CBL. The joining portion  134  is provided with the VBS line mounting portion  137 . The VBS lines  132 A and  132 B are electrically coupled to the COF  60  through the VBS line mounting portion  137  and the joining portion  134 . The VBS lines  132 A and  132 B are electrically coupled to the COF  60  at a position on another side relative to the lines of pressure chambers CAL and CBL. 
     The liquid ejecting head  10 C according to the above-described Embodiment 3 also takes into account the effects of the voltage drops due to the VBS lines  131 A,  131 B,  132 A and  132 B in the y-axis direction. According to the above-described liquid ejecting head  10 C, the variation in ejection of the liquid among the nozzles N arranged in the y-axis direction is suppressed. 
     Embodiment 4 
     Next, a liquid ejecting head  10 D according to Embodiment 4 will be described with reference to  FIG.  13   .  FIG.  13    is an enlarged plan view illustrating a principal part of the liquid ejecting head according to the Embodiment 4. The liquid ejecting head  10 D according to the Embodiment 4 is different from the liquid ejecting head  10 B according to the Embodiment 2 in that the liquid ejecting head  10 D includes a joining portion  141  that joins the VBS line  121 A to the VBS line  122 B, includes a joining portion  142  that joins the VBS line  121 B to the VBS line  122 A, includes a VBS line mounting portion  146  provided to the joining portion  141 , and includes a VBS line mounting portion  147  provided to the joining portion  142 . In the description of the Embodiment 4, the same explanations as those in the Embodiments 1 to 3 may be omitted as appropriate. 
     The liquid ejecting head  10 D includes the VBS lines  121 A and  122 A on the line A side, and the VBS lines  121 B and  122 B on the line B side. The VBS lines  121 A and  122 A are electrically coupled to the common electrode  52 A on the line A side. The VBS lines  121 B and  122 B are electrically coupled to the common electrode  52 B on the line B side. 
     The liquid ejecting head  10 D includes the joining portions  141  and  142 , and the VBS line mounting portions  146  and  147 . The joining portion  141  extends in the x-axis direction and joins end portions  121   c  and  122   e  of the VBS lines  121 A and  122 B to each other. The end portion  121   c  of the VBS line  121 A is located in the y1 direction relative to the line of pressure chambers CAL. The end portion  122   e  of the VBS line  122 B is located in the y1 direction relative to the line of pressure chambers CBL. The joining portion  141  joins the VBS line  121 A on the outer side and on the line A side to the VBS line  122 B on the inner side and on the line B side. The joining portion  141  is located in the y1 direction relative to the lines of pressure chambers CAL and CBL. The joining portion  141  is provided with the VBS line mounting portion  146 . The VBS lines  121 A and  122 B are electrically coupled to the COF  60  through the VBS line mounting portion  146  and the joining portion  141 . The VBS lines  121 A and  122 B are electrically coupled to the COF  60  at a position on one side relative to the lines of pressure chambers CAL and CBL. 
     The joining portion  142  extends in the x-axis direction and joins end portions  122   d  and  121   f  of the VBS lines  122 A and  121 B to each other. The end portion  122   d  of the VBS line  122 A is located in the y2 direction relative to the line of pressure chambers CAL. The end portion  121   f  of the VBS line  121 B is located in the y2 direction relative to the line of pressure chambers CBL. The joining portion  142  joins the VBS line  122 A on the inner side and on the line A side to the VBS line  121 B on the outer side and on the line B side. The joining portion  142  is located in the y2 direction relative to the lines of pressure chambers CAL and CBL. The joining portion  142  is provided with the VBS line mounting portion  147 . The VBS lines  122 A and  121 B are electrically coupled to the COF  60  through the VBS line mounting portion  147  and the joining portion  142 . The VBS lines  122 A and  121 B are electrically coupled to the COF  60  at a position on another side relative to the lines of pressure chambers CAL and CBL. 
     The liquid ejecting head  10 D according to the above-described Embodiment 4 also takes into account the effects of the voltage drops due to the VBS lines  121 A,  121 B,  122 A and  122 B in the y-axis direction. According to the above-described liquid ejecting head  10 D, the variation in ejection of the liquid among the nozzles N arranged in the y-axis direction is suppressed. 
     Embodiment 5 
     Next, a liquid ejecting head  10 E according to Embodiment 5 will be described with reference to  FIG.  14   .  FIG.  14    is an enlarged plan view illustrating a principal part of the liquid ejecting head according to the Embodiment 5. The liquid ejecting head  10 E according to the Embodiment 5 is different from the liquid ejecting head  10  according to the Embodiment 1 in that the liquid ejecting head  10 E includes a VBS line  151 A instead of the VBS line  55 A, and includes a VBS line  151 B instead of the VBS line  55 B. In the description of the Embodiment 5, the same explanations as those in the Embodiments 1 to 4 may be omitted as appropriate. The VBS line  151 A represents an example of the “first common line”. The VBS line  151 B represents an example of the “second common line”. 
     The liquid ejecting head  10 E includes the VBS line  151 A on the line A side and the VBS line  151 B on the line B side. The VBS line  151 A is electrically coupled to the common electrode  52 A on the line A side. The VBS line  151 B is electrically coupled to the common electrode  52 B on the line B side. 
     The VBS line  151 A includes a first portion  157 A that extends in the y-axis direction, a second portion  158 A that protrudes in the y1 direction from the first portion  157 A, and a third portion  159 A that protrudes in the x2 direction from the second portion  158 A. The first portion  157 A is provided in such a way as to cover the line of pressure chambers CAL when viewed in the z-axis direction. The first portion  157 A has such a length in the y-axis direction that faces the line of pressure chambers CAL. The length of the first portion  157 A in the y-axis direction is substantially equal to a length of the line of pressure chambers CAL. 
     The third portion  159 A is provided with the VBS line mounting portion  56 A. The VBS line  151 A is electrically coupled to the COF  60  through the VBS line mounting portion  56 A. 
     The first portion  157 A includes a first end portion  157   c  and a second end portion  157   d . The first end portion  157   c  is an end portion in the y1 direction and the second end portion  157   d  is an end portion in the y2 direction. The first end portion  157   c  is located in the y1 direction relative to the line of pressure chambers CAL. The second end portion  157   d  is located in the y2 direction relative to the line of pressure chambers CAL. A width W1 in the x-axis direction of the first end portion  157   c  is larger than a width W2 in the x-axis direction of the second end portion  157   d . In the y-axis direction, the width W1 of the first end portion  157   c  close to the VBS line mounting portion  56 A is larger than the width W2 of the second end portion  157   d  far from the VBS line mounting portion  56 A. The width of the first portion  157 A becomes larger as it is closer to the VBS line mounting portion  56 A and becomes smaller as it is farther from the VBS line mounting portion  56 A. 
     The VBS line  151 B includes a first portion  157 B that extends in the y-axis direction, a second portion  158 B that protrudes in the y2 direction from the first portion  157 B, and a third portion  159 B that protrudes in the x1 direction from the second portion  158 B. The first portion  157 B is provided in such a way as to cover the line of pressure chambers CBL when viewed in the z-axis direction. The first portion  157 B has such a length in the y-axis direction that faces the line of pressure chambers CBL. The length in the first portion  157 B in the y-axis direction is substantially equal to a length of the line of pressure chambers CBL. 
     The third portion  159 B is provided with the VBS line mounting portion  56 B. The VBS line  151 B is electrically coupled to the COF  60  through the VBS line mounting portion  56 B. 
     The first portion  157 B includes a first end portion  157   e  and a second end portion  157   f . The first end portion  157   e  is an end portion in the y1 direction and the second end portion  157   f  is an end portion in the y2 direction. The first end portion  157   e  is located in the y1 direction relative to the line of pressure chambers CBL. The second end portion  157   f  is located in the y2 direction relative to the line of pressure chambers CBL. A width W3 in the x-axis direction of the first end portion  157   e  is smaller than a width W4 in the x-axis direction of the second end portion  157   f . In the y-axis direction, the width W4 of the second end portion  157   f  close to the VBS line mounting portion  56 B is larger than the width W3 of the first end portion  157   e  far from the VBS line mounting portion  56 B. The width of the first portion  157 B becomes larger as it is closer to the VBS line mounting portion  56 B and becomes smaller as it is farther from the VBS line mounting portion  56 B. The width W1 and the width W4 are substantially equal. The width W2 and the width W3 are substantially equal. 
     According to the liquid ejecting head  10 E of the above-described Embodiment 5, the width of the first portion  157 A of the VBS line  151 A on the line A side becomes larger as it is away in the y1 direction from the center line OX and becomes smaller as it is away in the y2 direction from the center line OX. On the other hand, the width of the first portion  157 B of the VBS line  151 B on the line B side becomes smaller as it is away in the y1 direction from the center line OX and becomes larger as it is away in the y2 direction from the center line OX. 
     The liquid ejecting head  10 E according to the above-described Embodiment 5 also takes into account the effects of the voltage drops due to the VBS lines  151 A and  151 B in the y-axis direction. According to the above-described liquid ejecting head  10 E, the variation in ejection of the liquid among the nozzles N arranged in the y-axis direction is suppressed. 
     Embodiment 6 
     Next, a liquid ejecting head  10 F according to Embodiment 6 will be described with reference to  FIGS.  15  and  16   .  FIG.  15    is a sectional view illustrating the pressure chambers CA1 and CA2 on the line A side of the liquid ejecting head  10 F according to the Embodiment 6. The liquid ejecting head  10 F according to the Embodiment 6 is different from the liquid ejecting head  10  according to the Embodiment 1 in that thicknesses T1 to T4 of the VBS lines  55 A and  55 B vary depending on the positions in the y-axis direction. In the description of the Embodiment 6, the same explanations as those in the Embodiments 1 to 5 may be omitted as appropriate. The thicknesses T1 to T4 represent thicknesses in the z-axis direction. 
     The pressure chamber CA1 illustrated in  FIG.  15    is the pressure chamber CA out of the pressure chambers CA, which is located at one end in the y-axis direction. The pressure chamber CA2 is the pressure chamber CA out of the pressure chambers CA, which is located at another end in the y-axis direction. The pressure chamber CA1 is located closest in the y-axis direction to the VBS line mounting portion  56 A out of the pressure chambers CA. The pressure chamber CA2 is located farthest in the y-axis direction from the VBS line mounting portion  56 A out of the pressure chambers CA. 
     The thickness T1 of the VBS line  55 A close to the pressure chamber CA1 is larger than the thickness T2 of the VBS line  55 A close to the pressure chamber CA2. The thickness of the VBS line  55 A becomes larger as it is located away in the y1 direction from the center line OX illustrated in  FIG.  8    and becomes smaller as it is located away in the y2 direction from the center line OX. 
     The pressure chamber CB1 illustrated in  FIG.  16    is the pressure chamber CB out of the pressure chambers CB, which is located at one end in the y-axis direction. The pressure chamber CB2 is the pressure chamber CB out of the pressure chambers CB, which is located at another end in the y-axis direction. The pressure chamber CB1 is located farthest in the y-axis direction from the VBS line mounting portion  56 B out of the pressure chambers CB. The pressure chamber CB2 is located closest in the y-axis direction to the VBS line mounting portion  56 B out of the pressure chambers CB. 
     The thickness T3 of the VBS line  55 B close to the pressure chamber CB1 is smaller than the thickness T4 of the VBS line  55 B close to the pressure chamber CB2. The thickness of the VBS line  55 B becomes smaller as it is located away in the y1 direction from the center line OX illustrated in  FIG.  8    and becomes larger as it is located away in the y2 direction from the center line OX. 
     In the liquid ejecting head  10 F according to the above-described Embodiment 6, the thickness of the VBS line  55 A on the line A side becomes larger as it is located away in the y1 direction from the center line OX and becomes smaller as it is located away in the y2 direction from the center line OX. On the other hand, the thickness of the VBS line  55 B on the line B side becomes smaller as it is located away in the y1 direction from the center line OX and becomes larger as it is located away in the y2 direction from the center line OX. 
     The liquid ejecting head  10 F according to the above-described Embodiment 6 also takes into account the effects of the voltage drops due to the VBS lines  55 A and  55 B in the y-axis direction. According to the above-described liquid ejecting head  10 F, the variation in ejection of the liquid among the nozzles N arranged in the y-axis direction is suppressed. 
     Embodiment 7 
     Next, a liquid ejecting head  10 G according to Embodiment 7 will be described with reference to  FIGS.  11  and  17   .  FIG.  17    is a sectional view illustrating the liquid ejecting head  10 G according to the Embodiment 7. The liquid ejecting head  10 G according to the Embodiment 7 is different from the liquid ejecting head  10  according to the Embodiment 1 illustrated in  FIG.  2    in that the liquid ejecting head  10 G includes nozzles NA communicating with the pressure chambers CA on the line A side and nozzles NB communicating with the pressure chambers CB on the line B side separately instead of the structure including the nozzles N communicating with the pressure chambers CA on the line A side and the pressure chambers CB on the line B side in common, and includes the VBS lines  121 A,  121 B,  122 A, and  122 B instead of the VBS lines  55 A and  55 B. The VBS lines  121 A,  121 B,  122 A, and  122 B of the liquid ejecting head  10 G according to the Embodiment 7 are the same as the VBS lines  121 A,  121 B,  122 A, and  122 B of the liquid ejecting head  10 B according to the Embodiment 2 illustrated in  FIG.  11   . In the description of the Embodiment 7, the same explanations as those in the Embodiment 1 to 6 may be omitted as appropriate. 
     The liquid ejecting head  10 G illustrated in  FIG.  17    includes the pressure chambers CA and CB. Each pressure chamber CA communicates with the common liquid chamber RA, the relay flow channel  43 A, the communication flow channel  45 A, and the nozzle NA. Each pressure chamber CB communicates with the common liquid chamber RB, the relay flow channel  43 B, the communication flow channel  45 B, and the nozzle NB. 
     The liquid ejecting head  10 G according to the above-described Embodiment 7 also takes into account the effects of the voltage drops due to the VBS lines  121 A,  121 B,  122 A, and  122 B in the y-axis direction. As illustrated in  FIG.  11   , the pressure chamber CA1 disposed at the one end in the y-axis direction is close to the VBS line mounting portion  56 A and is far from the VBS line mounting portion  127 A. The common electrode  52 A above the pressure chamber CA1 is electrically coupled to the close VBS line mounting portion  56 A through the VBS line  121 A, and is electrically coupled to the far VBS line mounting portion  127 A through the VBS line  122 A. 
     The pressure chamber CA2 disposed at the other end in the y-axis direction is far from the VBS line mounting portion  56 A and is close to the VBS line mounting portion  127 A. The common electrode  52 A above the pressure chamber CA2 is electrically coupled to the far VBS line mounting portion  56 A through the VBS line  121 A, and is electrically coupled to the close VBS line mounting portion  127 A through the VBS line  122 A. The common electrode  52 B to the pressure chambers CB, CB1, and CB2 on the line B side is also electrically coupled to the VBS line mounting portions  56 B and  176 B located on mutually opposite sides, respectively. 
     According to the liquid ejecting head  10 G of the above-described Embodiment 7, the effects of the voltage drops due to the VBS lines  121 A,  121 B,  122 A, and  122 B in the y-axis direction are taken into account. Thus, the variation in ejection of the liquid among the nozzles NA and NB arranged in the y-axis direction is suppressed. 
     The liquid ejecting head  10 G according to the Embodiment 7 includes the VBS lines  121 A,  121 B,  122 A, and  122 B as well as the VBS line mounting portions  56 A,  56 B,  127 A, and  127 B, which are the same as those of the Embodiment 2 illustrated in  FIG.  11   . However, the layout of the VBS lines  121 A,  121 B,  122 A, and  122 B as well as the VBS line mounting portions  56 A,  56 B,  127 A, and  127 B is not limited only to the foregoing. The liquid ejecting head  10 G may be configured to include the VBS lines  121 A,  121 B,  122 A,  122 B,  131 A,  131 B,  132 A, and  132 B as illustrated in  FIG.  12  or  13   . The VBS lines  121 A,  121 B,  122 A, and  122 B of the liquid ejecting head  10 G may have the thicknesses T1 to T4 that vary depending on the positions in the y-axis direction as with the Embodiment 6. 
     Liquid Ejecting Apparatus 
     Next, a liquid ejecting apparatus  1  including the liquid ejecting head  10  will be described with reference to  FIGS.  18  and  19   .  FIG.  18    is a schematic diagram illustrating the liquid ejecting apparatus  1  including the liquid ejecting head  10 . The liquid ejecting apparatus  1  includes the liquid ejecting head  10  according to the above-described Embodiment 1.  FIG.  19    is a block diagram illustrating the liquid ejecting apparatus  1 . The liquid ejecting apparatus  1  is not limited to the structure that includes the liquid ejecting head  10  according to the Embodiment 1. The liquid ejecting apparatus  1  may include any of the liquid ejecting heads  10 B to  10 G according to the Embodiments 2 to 7 instead of the liquid ejecting head  10  according to the Embodiment 1. 
     The liquid ejecting apparatus  1  is an ink jet type printing apparatus that ejects an ink in the form of droplets, which represents an example of a “liquid”, onto a medium PA. The liquid ejecting apparatus  1  is a serial type printing apparatus. The medium PA is typically a sheet of printing paper. The medium PA is not limited only to the printing paper, and may be a printing target of a desired material such as a resin film and a cloth. 
     The liquid ejecting apparatus  1  includes the liquid ejecting head  10  that ejects inks, the liquid containers  2  that store inks, a carriage  3  that mounts the liquid ejecting head  10 , a carriage transportation mechanism  4  that transports the carriage  3 , a medium transportation mechanism  5  that transports the medium PA, and the control unit  30 . The control unit  30  is a control unit that controls ejection of the liquids. 
     Examples of specific aspects of the liquid container  2  include a cartridge attachable to and detachable from the liquid ejecting apparatus  1 , an ink pack in the form of a bag formed from a flexible film, and an ink-refillable ink tank. An arbitrary type of the ink may be stored in the liquid container  2 . The liquid ejecting apparatus  1  includes multiple liquid containers  2  corresponding to inks of four colors, for instance. Examples of the inks of four colors include cyan, magenta, yellow, and black inks. The liquid containers  2  may be mounted on the carriage  3 . 
     The liquid ejecting apparatus  1  includes the circulation mechanism  8  that circulates the inks. The circulation mechanism  8  includes the supply flow channels  81  that supply the inks to the liquid ejecting head  10 , the collection flow channels  82  that collect the inks discharged from the liquid ejecting head  10 , and the pumps  83  that transfer the inks. 
     The carriage transportation mechanism  4  includes a transportation belt  4   a  for transporting the carriage  3 , and a motor. The medium transportation mechanism  5  includes a transportation roller  5   a  for transporting the medium PA, and a motor. The carriage transportation mechanism  4  and the medium transportation mechanism  5  are controlled by the control unit  30 . The liquid ejecting apparatus  1  causes the carriage transportation mechanism  4  to transport the carriage  3  while causing the medium transportation mechanism  5  to transport the medium PA, and performs printing by ejecting the ink droplets onto the medium PA. 
     As illustrated in  FIG.  19   , the liquid ejecting apparatus  1  includes a linear encoder  6 . The linear encoder  6  is provided at a position where it is possible to detect a position of the carriage  3 . The linear encoder  6  obtains information concerning the position of the carriage  3 . The linear encoder  6  outputs an encoder signal to the control unit  30  along with a movement of the carriage  3 . 
     The control unit  30  includes one or more CPUs  31 . The control unit  30  may include an FPGA instead of or in addition to the CPUs  31 . The control unit  30  includes a storage unit  35 . The storage unit  35  includes a ROM  36  and a RAM  37 , for example. The storage unit  35  may include an EEPROM or a PROM. The storage unit  35  can store print data Img supplied from a host computer. The storage unit  35  stores a control program for the liquid ejecting apparatus  1 . 
     The CPU stands for central processing unit. The FPGA stands for field-programmable gate array. The RAM stands for random access memory. The ROM stands for read only memory. the EEPROM stands for electrically erasable programmable read only memory. The PROM stands for programmable ROM. 
     The control unit  30  generates signals for controlling operations of the respective units in the liquid ejecting apparatus  1 . The control unit  30  can generate a print signal SI and a waveform designation signal dCom. The print signal SI is a digital signal for defining a type of an operation of the liquid ejecting head  10 . The print signal SI can designate whether or not to supply the driving signal Com to each piezoelectric element  50 . The waveform designation signal dCom is a digital signal that defines a waveform of the driving signal Com. The driving signal Com is an analog signal for driving the piezoelectric element  50 . 
     The liquid ejecting apparatus  1  includes the driving signal generation circuit  32 . The driving signal generation circuit  32  is electrically coupled to the control unit  30 . The driving signal generation circuit  32  includes a DA converter circuit. The driving signal generation circuit  32  generates the driving signal Com having the waveform defined by the waveform designation signal dCom. When the control unit  30  receives the encoder signal from the linear encoder  6 , the control unit  30  outputs a timing signal PTS to the driving signal generation circuit  32 . The timing signal PTS defines timing to generate the driving signal Com. The driving signal generation circuit  32  outputs the driving signal Com every time the driving signal generation circuit  32  receives the timing signal PTS. 
     The driving circuit  62  is electrically coupled to the control unit  30  and to the driving signal generation circuit  32 . The driving circuit  62  switches whether or not to supply the driving signal Com to the piezoelectric element  50  based on the print signal SI. The driving circuit  62  can select the piezoelectric element  50 , to which the driving signal Com is supplied, based on the print signal SI, a latch signal LAT, and a change signal CH that are supplied from the control unit  30 . The latch signal LAT defines timing to latch the print data Img. The change signal CH defines timing to select a driving pulse included in the driving signal Com. 
     The control unit  30  controls an ink ejection operation by the liquid ejecting head  10 . As described above, the control unit  30  drives the piezoelectric element  50  so as to change the pressure of the ink inside the pressure chamber C, thereby ejecting the ink from the nozzle N. The control unit  30  controls the ejection operation when performing a printing operation. 
     This liquid ejecting apparatus  1  can apply the above-described liquid ejecting head  10 . In the liquid ejecting apparatus  1  including the liquid ejecting head  10 , the VBS line mounting portion  56 A on the line A side and the VBS line mounting portion  56 B on the line B side are disposed on mutually opposite sides in the y-axis direction. The voltage is supplied in mutually opposite directions to the VBS line  55 A on the line A side and to the VBS line  55 B on the line B side. Thus, the effects of the voltage drops based on the distances from the VBS line mounting portions  56 A and  56 B are cancelled between the piezoelectric elements  50 A on the line A side and the piezoelectric elements  50 B on the line B side. Accordingly, the variation in ejection of the liquid between the nozzles N is suppressed. As a consequence, reliability of the liquid ejecting apparatus  1  including the liquid ejecting head  10  is improved. 
     Modified Example 1 
     Next, a liquid ejecting head  10  according to Modified Example 1 will be described. The liquid ejecting head  10  according to the Modified Example 1 is different from the liquid ejecting head  10  according to the Embodiments in that widths in the x-axis direction of the VBS lines  55 A and  55 B are different depending on positions in the y-axis direction. The same explanations as the explanations in the above-described Embodiments 1 to 7 may be omitted as appropriate. 
     In the liquid ejecting head  10  according to the Modified Example 1, the VBS line mounting portion  56 A is disposed on an end on one side while the VBS line mounting portion  56 B is disposed on an end on another side. The VBS line  55 A is electrically coupled to the VBS line mounting portion  56 A and the VBS line  55 B is electrically coupled to the VBS line mounting portion  56 B. 
     In the liquid ejecting head  10  according to the Modified Example 1, the VBS line  55 A on the line A side is formed such that electric resistance of the VBS line  55 A is gradually reduced from the one side to the other side in the y-axis direction. To be more precise, a width W11 at the end on the one side of the VBS line  55 A is smaller than a width W12 at the end on the other side of the VBS line  55 A. The width W11 and the width W1 indicated in  FIG.  14    are measured at the same position in the y-axis direction, and the width W12 and the width W2 are measured at the same position in the y-axis direction. 
     In the liquid ejecting head  10  according to the Modified Example 1, the VBS line  55 B on the line B side is formed such that electric resistance of the VBS line  55 B is gradually reduced from the other side to the one side in the y-axis direction. To be more precise, a width W13 at the end on the one side of the VBS line  55 B is larger than a width W14 at the end on the other side of the VBS line  55 B. The width W13 and the width W3 indicated in  FIG.  14    are measured at the same position in the y-axis direction, and the width W14 and the width W4 are measured at the same position in the y-axis direction. 
     The liquid ejecting head  10  according to the above-described Modified Example 1 also takes into account the effects of the voltage drops due to the VBS lines  55 A and  55 B in the y-axis direction. Accordingly, the variation in ejection of the liquid among the nozzles NA and NB arranged in the y-axis direction is suppressed. 
     Modified Example 2 
     Next, a liquid ejecting head  10  according to Modified Example 2 will be described. The liquid ejecting head  10  according to the Modified Example 2 is different from the liquid ejecting head  10  according to the Embodiments in that thicknesses in the z-axis direction of the VBS lines  55 A and  55 B vary depending on positions in the y-axis direction. The same explanations as the explanations in the above-described Embodiments 1 to 7 and Modified Example 1 may be omitted as appropriate. 
     In the liquid ejecting head  10  according to the Modified Example 2, the VBS line  55 A on the line A side is formed such that electric resistance of the VBS line  55 A is gradually reduced from the one side to the other side in the y-axis direction. To be more precise, a thickness T11 at the end on the one side of the VBS line  55 A is smaller than a thickness T12 at the end on the other side of the VBS line  55 A (T11&lt;T12). 
     In the liquid ejecting head  10  according to the Modified Example 2, the VBS line  55 B on the line B side is formed such that electric resistance of the VBS line  55 B is gradually decreased from the other side to the one side in the y-axis direction. To be more precise, a thickness T13 at the end on the one side of the VBS line  55 B is larger than a thickness T14 at the end on the other side of the VBS line  55 B (T13&gt;T14). 
     The liquid ejecting head  10  according to the above-described Modified Example 2 also takes into account the effects of the voltage drops due to the VBS lines  55 A and  55 B in the y-axis direction. Accordingly, the variation in ejection of the liquid among the nozzles NA and NB arranged in the y-axis direction is suppressed. 
     The above-described Embodiments merely demonstrate representative examples of the present disclosure. The present disclosure is not limited only to the above-described Embodiments, and various modifications and additions are possible within the range not departing from the gist of the present disclosure. 
     The above-described Embodiments exemplify the case in which the VBS lines  55 A and  55 B are electrically coupled to the COF  60  on the outer sides of the lines of pressure chambers CAL and CBL in the y-axis direction. However, the positions where the VBS lines  55 A and  55 B are electrically coupled to the COF  60  are not limited only to this configuration. For example, the position where the VBS line  55 A is electrically coupled to the COF  60  may be a position shifted in the y1 direction from the center line OX. The position where the VBS line  55 B is electrically coupled to the COF  60  may be a position shifted in the y2 direction from the center line OX. For example, the position where the VBS line  55 A is electrically coupled to the COF  60  may be a position overlapping the line of pressure chambers CAL when viewed in the z-axis direction and being shifted in the y1 direction from the center line OX. The position where the VBS line  55 B is electrically coupled to the COF  60  may be a position overlapping the line of pressure chambers CBL when viewed in the z-axis direction and being shifted in the y2 direction from the center line OX. The “one side” is not limited to the position shifted in the y1 direction from the center line OX and may be position shifted in the y2 direction. Likewise, the “other side” is not limited to the position shifted in the y2 direction from the center line OX and may be position shifted in the y1 direction. The “one side” and the “other side” are mutually opposite sides based on the center line OX. 
     In the above-described Embodiment 1, the VBS line  55 A is electrically coupled to the COF  60  at the position on the one side, but is not electrically coupled to the COF  60  at a position on the other side. Likewise, in the Embodiment 1, the VBS line  55 B is electrically coupled to the COF  60  at the position on the other side, but is not electrically coupled to the COF  60  at a position on the one side. 
     The COM line  54 A, the COM line  54 B, the VBS line  55 A, and the VBS line  55 B are electrically coupled to the COF  60 , respectively. Nonetheless, the COM line  54 A, the COM line  54 B, the VBS line  55 A, and the VBS line  55 B are coupled to different wiring portions of the COF  60  and are not coupled to a common wiring portion. 
     The VBS line  55 A is provided such that its wiring resistance varies gradually from the one side to the other side in the y-axis direction, and the VBS line  55 B is provided such that its wiring resistance varies gradually from the other side to the one side in the y-axis direction. As described above, the wiring resistance can be made variable by changing the width of each VBS line or changing the thickness of the VBS line. 
     For example, the VBS line on the line A side may be provided such that its wiring resistance is gradually increased from the one side to the other side in the y-axis direction, and the VBS line on the line B side may be provided such that its wiring resistance is gradually increased from the other side to the one side in the y-axis direction. 
     For example, the VBS line on the line A side may be provided such that its wiring resistance is gradually decreased from the one side to the other side in the y-axis direction, and the VBS line on the line B side may be provided such that its wiring resistance is gradually decreased from the other side to the one side in the y-axis direction. 
     The above-described Embodiment 1 shows the example of the liquid ejecting head  10  configured to circulate the liquid. However, the present disclosure is also applicable to a liquid ejecting head  10  not configured to circulate the liquid. 
     The above-described Embodiment 1 exemplifies the case where two pressure chambers in total, namely, one first pressure chamber CA and one second pressure chamber CB communicate with one nozzle N. Instead, four pressure chambers in total, namely, two pressure first chambers CA adjacent to each other in the y-axis direction and two second pressure chambers CB adjacent to each other in the y-axis direction may communicate with one nozzle N. 
     The above-described Embodiments shows the example of the serial type liquid ejecting apparatus that reciprocates the carriage mounting the liquid ejecting head  10  in the width direction of the medium PA. Instead, the present disclosure is also applicable to a line type liquid ejecting apparatus  1  provided with a line head that mounts multiple liquid ejecting heads  10 . 
     The liquid ejecting apparatus  1  shown as the example in any of the above-described Embodiments can be adopted to various apparatuses such as a facsimile apparatus and a copier besides the apparatus dedicated for printing. After all, the use of the liquid ejecting apparatus of the present disclosure is not limited only to the printing. For example, a liquid ejecting apparatus configured to eject a solution of a coloring material is used as a manufacturing apparatus for forming color filters of display devices such as liquid crystal display panels. A liquid ejecting apparatus configured to eject a solution of a conductive material is used as a manufacturing apparatus for forming wiring and electrodes on wiring boards. A liquid ejecting apparatus configured to eject a solution of a biological organic substance is used as a manufacturing apparatus for manufacturing biochips, for example.