Patent Publication Number: US-2023150259-A1

Title: Liquid Ejecting Head and Liquid Ejecting Apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-184537, filed Nov. 12, 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 described in JP-A-2021-130258 includes nozzles from which a liquid is ejected, pressure chambers which communicate with the nozzles, a supply flow channel through which the liquid is supplied to the pressure chambers, and a discharge flow channel through which the liquid discharged from the pressure chambers is discharged. The liquid not ejected from the nozzles is discharged from the pressure chambers and flows through the discharge flow channel. The liquid ejecting head includes a supply-side compliance substrate which absorbs vibrations of the liquid inside the supply flow channel, and a discharge-side compliance substrate which absorbs vibrations of the liquid inside the discharge flow channel. 
     In the liquid ejecting head according to the related art, the supply-side compliance substrate and the discharge-side compliance substrate have the same size. The liquid flowing through the supply flow channel and the liquid flowing through the discharge flow channel differ in flow rate. Thus, for the sizes of the supply-side compliance substrate and the discharge-side compliance substrate, there is still room for consideration. 
     SUMMARY 
     A liquid ejecting head according to an aspect of the present disclosure includes: a nozzle from which a liquid is ejected; a pressure chamber in which a pressure is applied to the liquid; a supply flow channel which is located on one side in a first direction relative to the pressure chamber and through which the liquid is supplied to the pressure chamber; a discharge flow channel which is located on another side in the first direction relative to the pressure chamber and through which the liquid is discharged from the pressure chamber; a supply-side compliance substrate which is provided so as to face the supply flow channel and absorbs a vibration of the liquid in the supply flow channel; and a discharge-side compliance substrate which is provided so as to face the discharge flow channel and absorbs a vibration of the liquid in the discharge flow channel. A length of the discharge-side compliance substrate in the first direction is shorter than a length of the supply-side compliance substrate in the first direction. 
     A liquid ejecting head according to another aspect of the present disclosure includes: a nozzle from which a liquid is ejected; a pressure chamber in which a pressure is applied to the liquid; a supply flow channel which is located on one side in a first direction relative to the pressure chamber and through which the liquid is supplied to the nozzle; a discharge flow channel which is located on another side in the first direction relative to the pressure chamber and through which the liquid is discharged from the nozzle; a supply-side compliance substrate which is provided so as to face the supply flow channel and absorbs a vibration of the liquid in the supply flow channel; and a discharge-side compliance substrate which is provided so as to face the discharge flow channel and absorbs a vibration of the liquid in the discharge flow channel. A length of the discharge-side compliance substrate in the first direction is longer than a length of the supply-side compliance substrate in the first direction. 
     A liquid ejecting apparatus of the present disclosure has one of the above liquid ejecting heads and a control unit which controls an ejection operation of ejecting a liquid 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 cross-sectional view illustrating the liquid ejecting head, and is a view illustrating a cross section taken along the II-II line in  FIG.  1   . 
         FIG.  3    is a plan view illustrating part of a communication plate according to Embodiment 1. 
         FIG.  4    is a plan view illustrating part of a pressure chamber substrate according to Embodiment 1. 
         FIG.  5    is a plan view illustrating part of a vibration plate, some piezoelectric elements, and part of vibration absorbing units. 
         FIG.  6    is a cross-sectional view illustrating a cross section taken along the VI-VI line in  FIG.  5   , and is a view illustrating the supply-side vibration absorbing unit. 
         FIG.  7    is a cross-sectional view illustrating part of the vibration plate and a piezoelectric element according to Embodiment 1. 
         FIG.  8    is a cross-sectional view illustrating a cross section taken along the VIII-VIII line in  FIG.  5   , and is a view illustrating the discharge-side vibration absorbing unit. 
         FIG.  9    is a plan view illustrating the length and width of the opening of a damper chamber formed under a compliance substrate. 
         FIG.  10    is a cross-sectional view illustrating the thickness of the compliance substrate. 
         FIG.  11    is a cross-sectional view illustrating a liquid ejecting head according to Embodiment 2. 
         FIG.  12    is a plan view illustrating part of a communication plate according to Embodiment 2. 
         FIG.  13    is a plan view illustrating part of a pressure chamber substrate according to Embodiment 2. 
         FIG.  14    is a cross-sectional view illustrating a liquid ejecting head according to Embodiment 3. 
         FIG.  15    is a cross-sectional view illustrating part of a supply-side vibration absorbing unit according to Embodiment 3. 
         FIG.  16    is a cross-sectional view illustrating part of a discharge-side vibration absorbing unit according to Embodiment 3. 
         FIG.  17    is a plan view illustrating part of a communication plate according to Embodiment 5. 
         FIG.  18    is a plan view illustrating part of a pressure chamber substrate according to Embodiment 5. 
         FIG.  19    is a cross-sectional view illustrating a liquid ejecting head according to Embodiment 8. 
         FIG.  20    is a schematic diagram illustrating a liquid ejecting apparatus according to an embodiment. 
         FIG.  21    is a block diagram illustrating the liquid ejecting apparatus according to the embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Embodiments of the present disclosure will be described below with reference to the drawings. It is to be noted that the dimensions and scales of portions in each drawing are made different from the actual ones as appropriate. Also, the embodiments to be discussed below are preferred specific examples of the present disclosure and thus involve various preferred technical limitations, but the scope of the present disclosure is not limited to these embodiments unless there is a particular statement indicating a limitation on the present disclosure in the following description. 
     In the following description, three directions crossing one another may be described as an X-axis direction, a Y-axis direction, and a Z-axis direction. The X-axis direction includes an X 1  direction and an X 2   direction which are opposite directions. The X-axis direction is an example of a first direction. The Y-axis direction includes a Y 1  direction and a Y 2  direction which are opposite directions. The Y-axis direction is an example of a second direction. The Z-axis direction includes a Z 1  direction and a Z 2  direction which are opposite directions. The Z direction is an example of a third direction. The X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to one another. The Z-axis direction is usually a direction along an up-down direction, but does not have to be a 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 Embodiment 1.  FIG.  2    is a cross-sectional view illustrating the liquid ejecting head  10 , and is a view illustrating a cross section taken along the II-II line in  FIG.  1   .  FIG.  3    is a partial plan view illustrating part of a communication plate  24 .  FIG.  4    is a partial plan view illustrating part of a pressure chamber substrate  25  according to Embodiment 1.  FIG.  5    is a plan view illustrating part of a vibration plate, some piezoelectric elements, and part of vibration absorbing units according to Embodiment 1. The liquid ejecting head  10  employs a circulation method in which a liquid having flowed through later-described common liquid chambers RA and RB and pressure chambers C is circulated. 
     Meanwhile, terms “supply side” and “discharge side” are sometimes used herein. “Supply side” refers to the side of a liquid flow channel upstream of the pressure chambers C. Also, things associated with the side upstream of the pressure chambers C may be referred to as “supply side”. For example, as will be seen later, terms such as “supply-side compliance substrate” may be used. “Discharge side” refers to the side of a liquid flow channel downstream of the pressure chambers C. “Discharge side” does not include nozzles N to be described later. Also, things associated with the side downstream of the pressure chambers C may be referred to as “discharge side”. For example, as will be seen later, terms such as “discharge-side compliance substrate” may be used. 
     The liquid ejecting head  10  includes a nozzle substrate  21 , the communication plate  24 , the pressure chamber substrate  25 , a vibration plate  26 , a sealing plate  27 , and piezoelectric elements  50 . The liquid ejecting head  10  also includes a case  28  and a COF  60 . COF stands for Chip on Film. The liquid ejecting head  10  has compliance substrates  23 A and  23 B and damper chambers DA and DB. In the present embodiment, a liquid ejecting head  10  that ejects an ink as an example of a liquid will be described. The liquid is not limited to an ink, and the liquid ejecting head  10  is capable of ejecting other kinds of liquids. 
     The thickness directions of the nozzle substrate  21 , the communication plate  24 , the pressure chamber substrate  25 , the vibration plate  26 , the sealing plate  27 , and the case  28  are oriented along the Z-axis direction. The nozzle substrate  21  is disposed at the bottom of the liquid ejecting head  10 . The communication plate  24  is disposed on the Z2-direction side of the nozzle substrate  21 . The pressure chamber substrate  25  is disposed on the Z2-direction side of the communication plate  24 . In other words, the communication plate  24  is provided between the pressure chamber substrate  25  and the nozzle substrate  21 . The vibration plate  26  and the compliance substrates  23 A and  23 B are formed on the Z2-direction side of the pressure chamber substrate  25 . 
     The sealing plate  27  is disposed on the Z2-direction side of the vibration plate  26  and the compliance substrates  23 A and  23 B. The sealing plate  27  includes portions situated outward of the compliance substrates  23 A and  23 B in the X-axis direction. These outer portions of the sealing plate  27  in the X-axis direction are located on the Z2-direction side of the pressure chamber substrate  25 . The sealing plate  27  cover the vibration plate  26 , the compliance substrates  23 A and  23 B, the plurality of piezoelectric elements  50 , and the pressure chamber substrate  25 . The case  28  is disposed on the sealing plate  27 . The piezoelectric elements  50  are provided respectively for the pressure chambers C. 
     Next, a flow channel  40  through which the ink flows will be described. In the liquid ejecting head  10 , the flow channel  40 , through which the ink flows, is formed. The flow channel  40  includes a supply port  42 A, a discharge port  42 B, the common liquid chambers RA and RB, the damper chambers DA and DB, the pressure chambers C, communication flow channels  47 A to  47 C, and the nozzles N. 
     The flow channel  40  has a supply flow channel  41 A and a discharge flow channel  41 B. The supply flow channel  41 A is a flow channel upstream of the pressure chambers C, and is a flow channel inside the communication plate  24  and the pressure chamber substrate  25 . The supply flow channel  41 A includes a flow channel  45 A, a communication flow channel  46 A, and the damper chambers DA. The discharge flow channel  41 B is a flow channel downstream of the pressure chambers C, and is a flow channel inside the communication plate  24  and the pressure chamber substrate  25 . The discharge flow channel  41 B includes the communication flow channels  47 C, the communication flow channels  47 B, the damper chambers DB, a flow channel  46 B, and a flow channel  45 B. The supply flow channel  41 A does not include the flow channel  44 A in the sealing plate  27  or a flow channel  43 A in the case  28 . The discharge flow channel  41 B does not include a flow channel  44 B in the sealing plate  27  or a flow channel  43 B in the case  28 . 
     The common liquid chamber RA is provided in common for the plurality of pressure chambers C. The common liquid chamber RA is continuous in the Y-axis direction. The common liquid chamber RA includes the flow channel  43 A provided in the case  28 , the flow channel  44 A provided in the sealing plate  27 , the flow channel  45 A provided in the pressure chamber substrate  25 , and the flow channel  46 A provided in the communication plate  24 . These flow channels  43 A,  44 A,  45 A, and  46 A are continuous with one another in the Z-axis direction. The flow channel  45 A and the flow channel  46 A are an example of a common supply flow channel. The flow channels  43 A and  44 A of the common liquid chamber RA are not included in the common supply flow channel. 
     The plurality of communication flow channels  47 A are provided respectively for the plurality of pressure chambers C. The plurality of communication flow channels  47 A are disposed downstream of the common liquid chamber RA. The communication flow channels  47 A communicate with the flow channel  46 A. 
     The plurality of damper chambers DA are provided respectively for the plurality of pressure chambers C. The plurality of damper chambers DA are provided respectively between the plurality of communication flow channels  47 A and the plurality of pressure chambers C. The damper chambers DA are located on the Z2-direction side of the communication flow channels  47 A. The damper chambers DA communicate with the side downstream of the communication flow channels  47 A. The damper chambers DA are located on the X1-direction side of the pressure chambers C. The damper chambers DA communicate with the side upstream of the pressure chambers C. The communication flow channels  47 A and the damper chambers DA are an example of “individual supply flow channels”. The damper chambers DA are supply-side damper chambers. 
     The plurality of nozzles N communicate with the plurality of pressure chambers C, respectively. The nozzles N are located on the Z1-direction side of the pressure chambers C. 
     The plurality of communication flow channels  47 C are provided respectively for the plurality of pressure chambers C. The plurality of communication flow channels  47 C communicate with the side downstream of the pressure chambers C. End portions of the pressure chambers C in the X 2  direction, which are downstream end portions, and end portions of the communication flow channels  47 C in the X 1  direction, which are upstream end portions, overlap each other as viewed from the Z-axis direction. 
     The plurality of communication flow channels  47 B are provided respectively for the plurality of communication flow channels  47 C. The communication flow channels  47 B are disposed downstream of the communication flow channels  47 C. 
     The plurality of damper chambers DB are provided respectively for the plurality of pressure chambers C. The damper chambers DB are located on the Z2-direction side of the communication flow channels  47 B. The plurality of damper chambers DB communicate respectively with the plurality of communication flow channels  47 B. The damper chambers DB communicate with the pressure chambers C through the communication flow channels  47 B and  47 C. The communication flow channels  47 B and  47 C and the damper chambers DB are an example of “individual discharge flow channels”. The damper chambers DB are discharge-side damper chambers. 
     The common liquid chamber RB is provided in common for the plurality of pressure chambers C. The common liquid chamber RB communicates in common with the plurality of communication flow channels  47 B. The common liquid chamber RB communicates with the pressure chambers C through the communication flow channels  47 B and  47 C. The common liquid chamber RB is disposed downstream of the communication flow channels  47 B. 
     The common liquid chamber RB is continuous in the Y-axis direction. The common liquid chamber RB includes the flow channel  43 B provided in the case  28 , the flow channel  44 B provided in the sealing plate  27 , the flow channel  45 B provided in the pressure chamber substrate  25 , and the flow channel  46 B provided in the communication plate  24 . These flow channels  43 B,  44 B,  45 B, and  46 B are continuous with one another in the Z-axis direction. The flow channel  45 B and the flow channel  46 B are an example of a common discharge flow channel. The flow channels  43 B and  44 B of the common liquid chamber RB are not included in the common discharge flow channel. 
     As mentioned above, the liquid ejecting head  10  employs a circulation method in which the ink having flowed through the pressure chambers C is circulated. As illustrated in  FIG.  20   , a circulating mechanism  8  that circulates the ink is coupled to the liquid ejecting head  10 . A liquid container  2  is coupled to the circulating mechanism  8 . The circulating mechanism  8  includes a supply flow channel  81  through which the ink is supplied to the liquid ejecting head  10 , a collection flow channel  82  through which the ink discharged from the liquid ejecting head  10  is collected, and a pump  83  which sends the ink. The supply flow channel  81  and the collection flow channel  82  may be flow channels inside tubes, for example. The supply flow channel  81  and the collection flow channel  82  include flow channels formed by openings, grooves, recesses, etc. 
     The ink in the liquid container  2  is sent by the pump  83  to flow through the supply flow channel  81  and pass through the supply port  42 A illustrated in  FIG.  2    to thereby flow into the common liquid chamber RA. The ink in the common liquid chamber RA passes through the communication flow channels  47 A and the damper chambers DA to thereby be supplied to the pressure chambers C. Part of the ink in the pressure chambers C is ejected from the nozzles N. 
     The ink not ejected from the nozzles N passes through the communication flow channels  47 C and the communication flow channels  47 B to thereby flow into the common liquid chamber RB. Part of the ink having flowed through the communication flow channels  47 C flows into the damper chambers DB. The ink in the common liquid chamber RB flows into the collection flow channel  82  through the discharge port  42 B and is collected into the liquid container  2 . The ink is circulated through the liquid ejecting head  10  in this manner. 
     Next, a structure of the liquid ejecting head  10  will be described. In the nozzle substrate  21  illustrated in  FIGS.  1  and  2   , the plurality of nozzles N are formed. The plurality of nozzles N form a nozzle array N 1 . The nozzle array N 1  includes the plurality of nozzles N arrayed in the Y-axis direction. The nozzles N are through-holes penetrating through the nozzle substrate  21  in the Z-axis direction. 
     As illustrated in  FIGS.  2  and  3   , in the communication plate  24 , there are formed the flow channel  46 A, which is a part of the common liquid chamber RA, the communication flow channels  47 A, the communication flow channels  47 C, the communication flow channels  47 B, and the flow channel  46 B, which is a part of the common liquid chamber RB. That is, part of the supply flow channels and part of the discharge flow channel are provided in the communication plate  24 . Through-holes, grooves, recesses, and the like are formed in the communication plate  24 . These through-holes, grooves, recesses, and the like form part of the common liquid chambers RA and RB and the communication flow channels  47 A,  47 B, and  47 C. 
     Part of the plurality of nozzles N is formed in the communication plate  24 . As illustrated in  FIG.  2   , the nozzles N penetrate through the communication plate  24  and the nozzle substrate  21  in the Z-axis direction. In the communication plate  24 , portions of the nozzles N closer to the pressure chambers C are formed. 
     As illustrated in  FIGS.  2  and  4   , in the pressure chamber substrate  25 , there are formed the flow channel  45 A, which is a part of the common liquid chamber RA, the plurality of damper chambers DA, the plurality of pressure chambers C, the plurality of damper chambers DB, and the flow channel  45 B, which is a part of the common liquid chamber RB. The plurality of nozzles N are illustrated with dashed lines in  FIG.  4   . The pressure chamber substrate  25  can be manufactured from a single-crystal substrate of silicon, for example. The pressure chamber substrate  25  may be manufactured from another material. 
     As illustrated in  FIG.  4   , the plurality of damper chambers DA extend in the X-axis direction. The damper chambers DA and the common liquid chamber RA are separated from each other in the X-axis direction. The damper chambers DA and the pressure chambers C are formed as common spaces continuous with each other in the X-axis direction. The damper chambers DA penetrate through the pressure chamber substrate  25  in the Z-axis direction. The damper chambers DA each have a predetermined volume. The plurality of damper chambers DA are disposed at predetermined intervals in the Y-axis direction. Incidentally, link flow channels may be formed between the damper chambers DA and the pressure chambers C. 
     The pressure chambers C extend in the X-axis direction. The pressure chambers C penetrate through the pressure chamber substrate  25  in the Z-axis direction. The pressure chambers C each have a predetermined volume. The plurality of pressure chambers C are disposed at predetermined intervals in the Y-axis direction. The plurality of pressure chambers C are disposed at the same positions as the plurality of damper chambers DA in the Y-axis direction. The plurality of pressure chambers C form a pressure chamber array CL arrayed in the Y-axis direction. The pressure chamber array CL includes the plurality of pressure chambers C. The long dashed double-short dashed lines in  FIG.  4    are phantom lines L 1  and L 2  indicating boundaries of the pressure chambers C. The phantom line L 1  indicates the ends of the pressure chambers C in the X 1  direction. The phantom line L 2  indicates the ends of the pressure chambers C in the X 2  direction. 
     The plurality of damper chambers DB extend in the X-axis direction. The damper chambers DB and the pressure chambers C are separated from each other in the X-axis direction. As illustrated in  FIG.  2   , the communication flow channels  47 C are formed between the damper chambers DB and the pressure chambers C. The damper chambers DB and the common liquid chamber RB are separated from each other in the X-axis direction. The damper chambers DB are formed so as to overlap the communication flow channels  47 B as viewed from the Z-axis direction. The damper chambers DB penetrate through the pressure chamber substrate  25  in the Z-axis direction. The damper chambers DB and the communication flow channels  47 B communicate with each other in the Z-axis direction. The damper chambers DB each have a predetermined volume. The plurality of damper chambers DB are disposed at predetermined intervals in the Y-axis direction. 
     As illustrated in  FIG.  4   , a width LX3 of the supply-side damper chambers DA in the X-axis direction is different from a length LX4 of the discharge-side damper chambers DB in the X-axis direction. The length LX3 of the supply-side damper chambers DA in the X-axis direction is longer than the length LX4 of the discharge-side damper chambers DB in the X-axis direction. The width of the damper chambers DA in the Y-axis direction is equal to the width of the damper chambers DB in the Y-axis direction. 
       FIG.  6    is a cross-sectional view illustrating a cross section taken along the VI-VI line in  FIG.  5   .  FIG.  7    is an enlarged cross-sectional view of part of the vibration plate  26 , a piezoelectric element  50 , and a COM wiring  54 . As illustrated in  FIGS.  6  and  7   , the vibration plate  26  is disposed on the upper surface of the pressure chamber substrate  25 . The vibration plate  26  covers openings in the pressure chamber substrate  25 . The portion of the vibration plate  26  covering the openings in the pressure chamber substrate  25  forms the upper wall surfaces of the pressure chambers C. 
     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 . 
     As illustrated in  FIGS.  5  to  7   , the plurality of piezoelectric elements  50  are formed on the vibration plate  26 . The piezoelectric elements  50  are disposed at positions overlapping the pressure chambers C as viewed from the Z-axis direction. The piezoelectric elements  50  are provided respectively for the plurality of pressure chambers C. 
     The vibration plate  26  vibrates in the Z-axis direction by being driven by the piezoelectric elements  50 . The portions of the vibration plate  26  forming the upper wall surfaces of the pressure chambers C are driven by the piezoelectric elements  50  above the pressure chambers C. The total thickness of the vibration plate  26  is 2 µm or less, for example. The total thickness of the vibration plate  26  may be 15 µm or less, 40 µm or less, or 100 µm or less. When the total thickness of the vibration plate  26  is, for example, 15 µm or less, it may include a resin layer. The vibration plate  26  may be formed from a metal. Examples of the metal include stainless steel, nickel, and so on. When the vibration plate  26  is formed from such a metal, the plate thickness of the vibration plate  26  may be 15 µm or more and 100 µm or less. 
     The piezoelectric element  50  illustrated in  FIGS.  6  and  7    has an individual electrode  51 , a common electrode  52 , and a piezoelectric layer  53 . The individual electrode  51 , the piezoelectric layer  53 , and the common electrode  52  are laminated in this order on the vibration plate  26 . The piezoelectric layer  53  is sandwiched between the individual electrode  51  and the common electrode  52 . The individual electrode  51  has an elongated shape along the X-axis direction. A plurality of the individual electrodes  51  are arrayed with a gap given therebetween in the Y-axis direction. The plurality of individual electrodes  51  are disposed respectively for the plurality of pressure chambers C. The individual electrodes  51  are disposed respectively at positions overlapping the plurality of pressure chambers C as viewed from the Z-axis direction. The common electrode  52  has a strip shape and extends in the Y-axis direction. The common electrode  52  is so continuous as to cover the plurality of individual electrodes  51 . 
     The individual electrodes  51  each include a foundation layer and an electrode layer. The foundation layer contains titanium (Ti), for example. The electrode layer contains an electrically conductive material with low resistance, such as platinum (Pt) or iridium (Ir), for example. This electrode layer may be formed of an oxide such as strontium ruthenate (SrRuO 3 ) or lanthanum nickelate (LaNiO 3 ), for example. The piezoelectric layer  53  is formed of a publicly known piezoelectric material such as lead zirconate titanate (Pb(Zr, Ti)O 3 ) or a ceramic, for example. 
     The common electrode  52  includes a foundation layer and an electrode layer. The foundation layer contains titanium, for example. The electrode layer contains an electrically conductive material with low resistance, such as platinum or iridium, for example. This electrode layer may be formed of an oxide such as strontium ruthenate or lanthanum nickelate, for example. The regions of the piezoelectric layer  53  between the individual electrodes  51  and the common electrode  52  serve as driving regions. The driving regions are formed respectively above the plurality of pressure chambers C. 
     A predetermined reference voltage is applied to the common electrode  52 . The reference voltage is a constant voltage and is set to be a voltage higher than a ground voltage, for example. A retention signal with a constant voltage, for example, is applied to the common electrode  52 . A driving signal with a variable voltage is applied to each individual electrode  51 . A voltage corresponding to the difference between the reference voltage applied to the common electrode  52  and the driving signal supplied to the individual electrode  51  is applied to the piezoelectric layer  53 . The driving signal corresponds to the ejection amount of the liquid to be ejected from the nozzle N. 
     Applying a voltage between the individual electrode  51  and the common electrode  52  deforms the piezoelectric layer  53 . As a result, the piezoelectric element  50  generates an energy that flexurally deforms the vibration plate  26 . 
     The energy generated by the piezoelectric element  50  vibrates the vibration plate  26 , so that the pressure on the liquid inside the pressure chamber C changes and the liquid inside the pressure chamber C gets ejected from the nozzle N. 
     As illustrated in  FIGS.  1  and  2   , the COF  60  includes a flexible wiring substrate  61  and a driving circuit  62 . The flexible wiring substrate  61  is a wiring substrate having flexibility. The flexible wiring substrate  61  is an FPC, for example. The flexible wiring substrate  61  may be an FFC, for example. FPC stands for Flexible Printed Circuit. FFC stands for Flexible Flat Cable. 
     As illustrated in  FIG.  2   , the flexible wiring substrate  61  is electrically coupled to the individual electrode  51  of each piezoelectric element  50  via the COM wiring  54  to be described later. The COM wiring  54  is illustrated in  FIGS.  2 ,  5 , and  7   . 
     Also, the flexible wiring substrate  61  is electrically coupled to the common electrode  52  of the piezoelectric elements  50  via a VBS wiring  55  to be described later. The flexible wiring substrate  61  is electrically coupled to a circuit substrate not illustrated. The circuit substrate includes a driving signal generating circuit  32  illustrated in  FIG.  21   . 
     The driving circuit  62  is mounted on the flexible wiring substrate  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.  21    through the flexible wiring substrate  61  and the circuit substrate. The driving circuit  62  receives a driving signal Com output from the driving signal generating circuit  32 . The switching element of the driving circuit  62  switches to supplying or not supplying the driving signal Com generated by the driving signal generating circuit  32  to the piezoelectric elements  50 . The driving circuit  62  supplies a driving voltage or current to the piezoelectric elements  50  to thereby vibrate the vibration plate  26 . 
     As illustrated in  FIGS.  5  and  7   , the liquid ejecting head  10  includes the COM wirings  54 . The plurality of COM wirings  54  are coupled respectively to the plurality of individual electrodes  51 . The plurality of COM wirings  54  run in the X-axis direction and are extended to the inside of an opening portion  27   a  of the sealing plate  27 . The opening portion  27   a  is illustrated in  FIGS.  1  and  2   . Illustration of the COM wirings  54  is omitted in  FIG.  1   . The opening portion  27   a  penetrates through the sealing plate  27  in the Z-axis direction. The COM wirings  54  are electrically coupled to the COF  60  at a position corresponding to the opening portion  27   a  as viewed from the Z-axis direction. The COM wirings  54  are formed of an electrically conductive material lower in resistance than the individual electrodes  51 . For example, the COM wirings  54  are electrically conductive patterns with a structure including an electrically conductive film formed of nichrome (NiCr) and an electrically conductive film of gold (Au) laminated on its surface. 
     As illustrated in  FIG.  7   , the COM wirings  54  each have an electrode layer  54   a , a first adhesion layer  54   b , and a first wiring layer  54   c . The electrode layer  54   a  covers the end surface of the piezoelectric layer  53  in the X 2  direction. The end surface in the X 2  direction is a surface crossing the X-axis direction. The first adhesion layer  54   b  covers the electrode layer  54   a  and the individual electrode  51 . The first adhesion layer  54   b  adheres to the electrode layer  54   a  and the individual electrode  51 . The first wiring layer  54   c  covers the first adhesion layer  54   b . The first wiring layer  54   c  is electrically coupled to the individual electrode  51  through the first adhesion layer  54   b . 
     The liquid ejecting head  10  includes the VBS wiring  55  electrically coupled to the COF  60  and the common electrode  52 . The VBS wiring  55  is disposed on the common electrode  52  and extends in the Y-axis direction. The VBS wiring has a strip shape as viewed from the Z-axis direction and is formed so as to cover the common electrode  52 . The VBS wiring  55  is electrically coupled to the COF  60  at an end portion of the liquid ejecting head  10  in the Y-axis direction. 
     Next, vibration absorbing units  70 A and  70 B will be described with reference to  FIGS.  2 ,  5 ,  6 , and  8   . The liquid ejecting head  10  includes a supply-side vibration absorbing unit  70 A and a discharge-side vibration absorbing unit  70 B. As illustrated in  FIGS.  2 ,  5 , and  6   , the supply-side vibration absorbing unit  70 A is provided for the supply-side damper chambers DA. As illustrated in  FIGS.  2 ,  5 , and  8   , the discharge-side vibration absorbing unit  70 B is provided for the discharge-side damper chambers DB. 
     As illustrated in  FIG.  6   , the vibration absorbing unit  70 A includes compliance substrates  23 A and piezoelectric elements  71 A. The compliance substrates  23 A are located on the X1-direction side of the vibration plate  26 . The compliance substrates  23 A are disposed on the upper surface of the pressure chamber substrate  25 . The compliance substrates  23 A cover the portions of the openings in the pressure chamber substrate  25  corresponding to the damper chambers DA. The compliance substrates  23 A form the upper wall surfaces of the damper chambers DA. As viewed from the Z-axis direction, the compliance substrates  23 A are disposed at positions corresponding to a sealing space S 2  formed in the sealing plate  27 . 
     The compliance substrates  23 A each include a flexible film. The compliance substrates  23 A each include an elastic layer  23   a  and an insulating layer  23   b . The elastic layer  23   a  is made of silicon dioxide (SiO 2 ), for example. The insulating layer  23   b  is made of zirconium dioxide (ZrO 2 ), for example. The elastic layer  23   a  is formed on the pressure chamber substrate  25 , and the insulating layer  23   b  is formed on the elastic layer  23   a . The elastic layer  23   a  is formed so as to be continuous with the elastic layer  26   a  of the vibration plate  26  covering the pressure chambers C. The insulating layer  23   b  is formed so as to be continuous with the insulating layer  26   b  of the vibration plate  26 . 
     The plurality of compliance substrates  23 A are provided respectively for the plurality of damper chambers DA arrayed in the Y-axis direction. The compliance substrates  23 A are deformable under a pressure from the ink. The compliance substrates  23 A can absorb variations in the pressure on the ink in the damper chambers DA by deforming under the pressure from the ink. The plurality of compliance substrates  23 A individually deform for the plurality of damper chambers DA. 
     As illustrated in  FIGS.  5  and  6   , the plurality of piezoelectric elements  71 A are formed on the compliance substrates  23 A. The piezoelectric elements  71 A are disposed at positions overlapping the damper chambers DA as viewed from the Z-axis direction. The piezoelectric elements  71 A are provided respectively for the plurality of damper chambers DA. 
     The piezoelectric elements  71 A each have an individual electrode layer  71   a , a common electrode layer  71   b , and a piezoelectric layer  71   c . The individual electrode layer  71   a , the common electrode layer  71   b , and the piezoelectric layer  71   c  are laminated in this order on the compliance substrate  23 A. The piezoelectric layer  71   c  is sandwiched between the individual electrode layer  71   a  and the common electrode layer  71   b . The individual electrode layer  71   a  has an elongated shape along the X-axis direction. A plurality of the individual electrode layers  71   a  are arrayed with a gap given therebetween in the Y-axis direction. The plurality of individual electrode layers  71   a  are disposed respectively for the plurality of damper chambers DA. The individual electrode layers  71   a  are disposed respectively at positions overlapping the plurality of damper chambers DA as viewed from the Z-axis direction. The common electrode layer  71   b  has a strip shape and extends in the Y-axis direction. The common electrode layer  71   b  is so continuous as to cover the plurality of individual electrode layers  71   a . 
     The structure and material of each individual electrode layer  71   a  are similar to those of the individual electrode  51  of each piezoelectric element  50 . The structure and material of the common electrode layer  71   b  are similar to those of the common electrode  52  of the piezoelectric element  50 . The structure and material of the piezoelectric layer  71   c  are similar to those of the piezoelectric layer  53  of the piezoelectric element  50 . The piezoelectric element  71 A can be formed in the film form similarly to the piezoelectric element  50 . 
     As illustrated in  FIGS.  2  and  5   , the compliance substrates  23 B are located on the X2-direction side of the vibration plate  26 . The compliance substrates  23 B are located on the opposite side of the vibration plate  26  from the compliance substrates  23 A in the X-axis direction. As illustrated in  FIG.  8   , the compliance substrates  23 B are disposed on the upper surface of the pressure chamber substrate  25 . The compliance substrates  23 B cover the portions of the openings in the pressure chamber substrate  25  corresponding to the damper chambers DB. The compliance substrates  23 B form the upper wall surfaces of the damper chambers DB. As viewed from the Z-axis direction, the compliance substrates  23 B are disposed at positions corresponding to a sealing space S 3  formed in the sealing plate  27 . 
     The compliance substrates  23 B each include a flexible film. The compliance substrates  23 B each include an elastic layer  23   c  and an insulating layer  23   d . The elastic layer  23   c  is made of silicon dioxide (SiO 2 ), for example. The insulating layer  23   d  is made of zirconium dioxide (ZrO 2 ), for example. The elastic layer  23   c  is formed on the pressure chamber substrate  25 , and the insulating layer  23   d  is formed on the elastic layer  23   c . The elastic layer  23   c  is formed so as to be continuous with the elastic layer  26   a  of the vibration plate  26 . The insulating layer  23   d  is formed so as to be continuous with the insulating layer  26   b  of the vibration plate  26 . 
     The plurality of compliance substrates  23 B are provided respectively for the plurality of damper chambers DB arrayed in the Y-axis direction. The compliance substrates  23 B are deformable under a pressure from the ink. The compliance substrates  23 B can absorb variations in the pressure on the ink in the damper chambers DB by deforming under the pressure from the ink. The plurality of compliance substrates  23 B individually deform for the plurality of damper chambers DB. 
     As illustrated in  FIGS.  5  and  8   , a plurality of piezoelectric elements  71 B are formed on the compliance substrates  23 B. The piezoelectric elements  71 B are disposed at positions overlapping the damper chambers DB as viewed from the Z-axis direction. The piezoelectric elements  71 B are provided respectively for the plurality of damper chambers DB. 
     The piezoelectric elements  71 B each have an individual electrode layer  71   d , a common electrode layer  71   e , and a piezoelectric layer  71   f . The individual electrode layer  71   d , the common electrode layer  71   e , and the piezoelectric layer  71   f  are laminated in this order on the compliance substrate  23 B. The piezoelectric layer  71   f  is sandwiched between the individual electrode layer  71   d  and the common electrode layer  71   e . The individual electrode layer  71   d  has an elongated shape along the X-axis direction. A plurality of the individual electrode layers  71   d  are arrayed with a gap given therebetween in the Y-axis direction. The plurality of individual electrode layers  71   d   are disposed respectively for the plurality of damper chambers DB. The individual electrode layers  71   d  are disposed respectively at positions overlapping the plurality of damper chambers DB as viewed from the Z-axis direction. The common electrode layer  71   e  has a strip shape and extends in the Y-axis direction. The common electrode layer  71   e  is so continuous as to cover the plurality of individual electrode layers  71   d . 
     The structure and material of each individual electrode layer  71   d  are similar to those of the individual electrode  51  of each piezoelectric element  50 . The structure and material of the common electrode layer  71   e  are similar to those of the common electrode  52  of the piezoelectric element  50 . The structure and material of the piezoelectric layer  71   f  are similar to those of the piezoelectric layer  53  of the piezoelectric element  50 . The piezoelectric element  71 B can be formed in the film form similarly to the piezoelectric elements  50  and  71 A. 
     The sealing plate  27  has a rectangular shape as viewed from the Z-axis direction. The sealing plate  27  protects the plurality of piezoelectric elements  50 ,  71 A, and  71 B and also reinforces the mechanical strength of the pressure chamber substrate  25 , the vibration plate  26 , and the compliance substrates  23 A and  23 B. The sealing plate  27  is bonded to the vibration plate  26  with an adhesive, for example. The sealing plate  27  is fixed to the pressure chamber substrate  25  via the vibration plate  26  and the compliance substrates  23 A and  23 B. 
     The sealing spaces S 1  to S 3  are formed in the sealing plate  27 . Recesses are formed in the lower surface of the sealing plate  27 . The spaces formed by these recesses are the sealing spaces S 1  to S 3 . The sealing spaces S 1  to S 3  are each formed so as to be continuous in the Y-axis direction. The sealing space S 1  is formed so as to overlap the plurality of pressure chambers C as viewed from the Z-axis direction. The sealing space S 1  houses the plurality of piezoelectric elements  50 . The sealing space S 2  is formed so as to overlap the plurality of damper chambers DA as viewed from the Z-axis direction. The sealing space S 2  houses the plurality of piezoelectric elements  71 A. The sealing space S 3  is formed so as to overlap the plurality of damper chambers DB as viewed from the Z-axis direction. The sealing space S 3  houses the plurality of piezoelectric elements  71 B. 
     In the sealing plate  27 , there are formed the flow channel  44 A included in the common liquid chamber RA and the flow channel  44 B included in the common liquid chamber RB. The flow channels  44 A and  44 B are formed so as to penetrate through the sealing plate  27  in the Z-axis direction. The flow channel  44 A is located on the X1-direction side of the sealing space S 2 . The flow channel  44 B is located on the X2-direction side of the sealing space S 3 . 
     The case  28  is located on the Z2-direction side of the sealing plate  27 . In the case  28 , the supply port  42 A, the discharge port  42 B, and the flow channels  43 A and  43 B are formed. The flow channel  43 A is included in the common liquid chamber RA. The flow channel  43 A is formed so as to overlap the flow channel  44 A in the sealing plate  27  as viewed from the Z-axis direction. The supply port  42 A communicates with the flow channel  43 A. The flow channel  43 B is included in the common liquid chamber RB. The flow channel  43 B is formed so as to overlap the flow channel  44 B in the sealing plate  27  as viewed from the Z-axis direction. The discharge port  42 B communicates with the flow channel  43 B. 
     Next, compliance substrates  77 A and  77 B provided in the common liquid chambers RA and RB will be described with reference to  FIG.  2   . As illustrated in  FIG.  2   , the liquid ejecting head  10  includes the compliance substrates  77 A and  77 B. The compliance substrates  77 A and  77 B are different from the compliance substrates  23 A and  23 B provided respectively for the damper chambers DA and DB. In  FIG.  2   , the configuration of the compliance substrates  77 A and  77 B is such that they are not exposed to the outside of the liquid ejecting head  10 . However, the configuration of the compliance substrates  77 A and  77 B may be such that they are exposed to the outside of the liquid ejecting head  10 . 
     The compliance substrate  77 A is provided for the flow channel  43 A of the common liquid chamber RA. The compliance substrate  77 A is located on the X1-direction side of the flow channel  43 A. The compliance substrate  77 A is disposed so as to cover an opening forming the flow channel  43 A. The thickness direction of the compliance substrate  77 A is oriented along the X-axis direction. The compliance substrate  77 A extends in the Y-axis direction. The compliance substrate  77 A is fixed to the case  28 . 
     The compliance substrate  77 B is provided for the flow channel  43 B of the common liquid chamber RB. The compliance substrate  77 B is located on the X2-direction side of the flow channel  43 B. The compliance substrate  77 B is disposed so as to cover an opening forming the flow channel  43 B. The thickness direction of the compliance substrate  77 B is oriented along the X-axis direction. The compliance substrate  77 B extends in the Y-axis direction. The compliance substrate  77 B is fixed to the case  28 . 
     The configurations of the compliance substrates  77 A and  77 B may be similar to those of the compliance substrates  23 A and  23 B, for example. The compliance substrates  77 A and  77 B each include an elastic layer and an insulating layer. The elastic layer is made of silicon dioxide (SiO 2 ), for example. The insulating layer is made of zirconium dioxide (ZrO 2 ), for example. 
     The compliance substrate  77 A is deformable under a pressure from the ink in the flow channel  43 A of the common liquid chamber RA. The compliance substrate  77 A can absorb variations in the pressure on the ink in the flow channel  43 A of the common liquid chamber RA by deforming under the pressure from the ink. 
     The compliance substrate  77 B is deformable under a pressure from the ink in the flow channel  43 B of the common liquid chamber RB. The compliance substrate  77 B can absorb variations in the pressure on the ink in the flow channel  43 B of the common liquid chamber RB by deforming under the pressure from the ink. 
     In the liquid ejecting head  10  according to Embodiment  1 , a length LX1 of the supply-side compliance substrates  23 A in the X-axis direction is longer than a length LX2 of the discharge-side compliance substrates  23 B in the X-axis direction. In the liquid ejecting head  10 , the ink is ejected from the nozzles N and therefore the flow rate of the liquid flowing through the discharge flow channel  41 B is lower than the flow rate of the liquid flowing through the supply flow channel  41 A. Crosstalk or the like has a less impact on the discharge flow channel  41 B than on the supply flow channel  41 A. Accordingly, the compliability required for the discharge flow channel  41 B is lower than that for the supply flow channel  41 A. The crosstalk here refers to a phenomenon in which vibrations resulting from the flow of a liquid through one individual flow channel (a flow channel including an individual supply flow channel and an individual discharge flow channel) affects a liquid flowing through another individual flow channel adjacent to the one individual flow channel and deteriorates ejection characteristics of the liquid in the other individual flow channel. As mentioned above, the flow rate in the discharge flow channel  41 B is lower than that in the supply flow channel  41 A. Thus, the length of the discharge-side compliance substrates  23 B in the X-axis direction does not need to be longer than that of the supply-side compliance substrates  23 A. In the liquid ejecting head  10 , the length LX2 of the discharge-side compliance substrates  23 B is made shorter than the length LX1 of the supply-side compliance substrates  23 A. In this way, the length of the liquid ejecting head  10  in the X-axis direction is shortened. This enables downsizing of the liquid ejecting head  10 . 
     In the liquid ejecting head  10  according to Embodiment  1 , the supply-side compliance substrates  23 A are made larger to ensure compliability on the supply side, while the discharge-side compliance substrates  23 B are made smaller to shorten the length of the liquid ejecting head  10  in the Y-axis direction, which enables space saving. With the liquid ejecting head  10 , it is possible to both ensure compliability and achieve space saving. 
     In the liquid ejecting head  10 , a length LX6 of the discharge flow channel  41 B is longer than a length LX5 of the supply flow channel  41 A. Here, the liquid ejecting head  10  is not limited to one in which the length LX6 of the discharge flow channel  41 B is longer than the length LX5 of the supply flow channel  41 A. When the length LX6 of the discharge flow channel  41 B is longer than the length LX5 of the supply flow channel  41 A and both have an equal cross-sectional area, the inertance of the discharge flow channel  41 B is greater than the inertance of the supply flow channel  41 A. Accordingly, the impact of crosstalk attenuates more easily in the discharge flow channel  41 B than in the supply flow channel  41 A. Considering that the inertance of the discharge flow channel  41 B is greater than that of the supply flow channel  41 A, it can be understood that the discharge-side compliance substrates  23 B may be shorter than the supply-side compliance substrates  23 A in the X-axis direction, even without taking into account the fact that the flow rate in the discharge flow channel  41 B is lower than the flow rate in the supply flow channel  41 A. 
     Also, in the liquid ejecting head  10 , the piezoelectric elements  71 A are provided on the compliance substrates  23 A. Thus, by deforming the piezoelectric elements  71 A with deformation of the compliance substrates  23 A, vibrations of the ink inside the damper chambers DA can be absorbed. Providing the piezoelectric elements  71 A on the compliance substrates  23 A reinforces the compliance substrates  23 A. The above applies also to the piezoelectric elements  71 B. 
     In the liquid ejecting head  10 , the vibration plate  26  and the compliance substrates  23 A and  23 B are formed integrally with each other, and the configurations of the piezoelectric elements  71 A and  71 B on the compliance substrates  23 A and  23 B are the same as the configuration of the piezoelectric elements  50  on the vibration plate  26 . This enables easy manufacture of the piezoelectric elements  71 A and  71 B. 
     In the liquid ejecting head  10 , a compliance amount CR of the discharge-side compliance substrates  23 B is smaller than a compliance amount CS of the supply-side compliance substrates  23 A. The compliance amounts CS and CR will be described later. When the compliance substrates  23 A and  23 B are the same in material, width in the Y-axis direction, and thickness in the Z-axis direction as in Embodiment  1 , the compliance amounts CS and CR are proportional to the lengths of the compliance substrates  23 A  and  23 B in the X-axis direction. In the liquid ejecting head  10 , the discharge-side compliance amount CR can be made smaller than the supply-side compliance amount CS. Compliance Amounts 
     Next, the compliance amounts CS and CR in the liquid ejecting head  10  will be described.  FIG.  9    is a plan view illustrating a length  1  and width w of the opening of the damper chamber DA formed under a compliance substrate  23 A.  FIG.  10    is a cross-sectional view illustrating a thickness t of the compliance substrate  23 A. 
     The compliance amount CS is a compliance amount in the supply flow channel  41 A. The compliance amount CR is a compliance amount in the discharge flow channel  41 B. The compliance amounts CS and CR satisfy Equation (1) below. The supply-side compliance amount CS is larger than the discharge-side compliance amount CR. The supply-side compliance amount CS is an example of the supply-side compliability. The discharge-side compliance amount CR is an example of the discharge-side compliability. 
     
       
         
           
             CS &gt; CR 
           
         
       
     
     Flow rates QS and QR of the ink flowing through the liquid ejecting head  10  satisfy Equation (2) below. The flow rate QS of the ink on the supply side is higher than the flow rate QR of the ink on the discharge side. The supply-side flow rate QS is the flow rate of the ink flowing through the supply flow channel  41 A. The discharge-side flow rate QR is the flow rate of the ink flowing through the discharge flow channel  41 B. 
     
       
         
           
             QS &gt; QR 
           
         
       
     
     When the supply-side compliance amount CS and the discharge-side compliance amount CR are not distinguished, they will be expressed as the compliance amount C. Likewise, when the compliance substrates  23 A and  23 B are not distinguished, they will be expressed as the compliance substrates  23 . The compliance amount C can be expressed using Equation (3) below. 
     
       
         
           
             C =  
             
               
                 1 
                 − 
                 
                   ν 
                   2 
                 
               
               
                 60 
                 E 
               
             
             • 
             
               
                 
                   w 
                   5 
                 
                   
                 l 
               
               
                 
                   t 
                   3 
                 
               
             
           
         
       
     
     In Equation (3), “V” denotes Poisson’s ratio of the compliance substrates  23 . “V” is a physical property value of the material forming the compliance substrates. “E” denotes Young’s modulus. “E” is a physical property value of the material forming the compliance substrates. 
     “w” denotes the width of the openings covered by the compliance substrates. “w” is the width of the damper chambers DA and DB in the Y-axis direction. “l” denotes the length of the openings covered by the compliance substrates. “t” denotes the thickness of the compliance substrates. 
     Case 1 
     When, for example, an inertance MS of the supply flow channel  41 A is lower than an inertance MR of the discharge flow channel  41 B, variations in the pressure on the ink in the pressure chambers C are transmitted more easily to the ink in the supply flow channel  41 A than to the ink in the discharge flow channel  41 B. In this case, the compliance amounts CS and CR are set to satisfy Equation (4). The supply-side compliance amount CS is larger than the discharge-side compliance amount CR. In Embodiment  1 , the inertance MS of the supply flow channel  41 A is lower than the inertance MR of the discharge flow channel  41 B. 
     
       
         
           
             CS &gt; CR 
           
         
       
     
     Case 2 
     When, for example, an inertance MS of the supply flow channel  41 A is higher than an inertance MR of the discharge flow channel  41 B, variations in the pressure on the ink in the pressure chambers C are transmitted more easily to the ink in the discharge flow channel  41 B than to the ink in the supply flow channel  41 A. In this case, the compliance amounts CS and CR are set to satisfy Equation (5). The supply-side compliance amount CS is larger than the discharge-side compliance amount CR. In later-described Embodiment  8 , the inertance MS of the supply flow channel  41 A is higher than the inertance MR of the discharge flow channel  41 B. 
     
       
         
           
             CS &lt; CR 
           
         
       
     
     Embodiment 2 
     Next, a liquid ejecting head  10 B according to Embodiment  2  will be described.  FIG.  11    is a cross-sectional view illustrating the liquid ejecting head  10 B according to Embodiment  2 .  FIG.  12    is a plan view illustrating part of a communication plate  24 B.  FIG.  13    is a plan view illustrating part of a pressure chamber substrate  25 B. The liquid ejecting head  10 B according to Embodiment  2  differs from the liquid ejecting head  10  according to Embodiment  1  illustrated in  FIG.  2    in that the former includes the communication plate  24 B in place of the communication plate  24 , the pressure chamber substrate  25 B in place of the pressure chamber substrate  25 , and vibration absorbing units  70 C and  70 D in place of the vibration absorbing units  70 A and  70 B. The description of Embodiment  2  may omit descriptions similar to those in Embodiment  1 . 
     As illustrated in  FIG.  11   , the liquid ejecting head  10 B includes a nozzle substrate  21 , the communication plate  24 B, the pressure chamber substrate  25 B, a vibration plate  26 , compliance substrates  23 C and  23 D, a sealing plate  27 , a case  28 , and a COF  60 . The liquid ejecting head  10 B includes the vibration absorbing units  70 C and  70 D. The supply-side vibration absorbing unit  70 C has the compliance substrate  23 C and piezoelectric elements  71 C. The discharge-side vibration absorbing unit  70 D has the compliance substrate  23 D and piezoelectric elements  71 D. 
     The liquid ejecting head  10 B has an ink flow channel  40 B. The ink flow channel  40 B has a supply flow channel  41 C and a discharge flow channel  41 D. The supply flow channel  41 C includes a flow channel  45 A, a flow channel  46 A, a communication flow channel  47 D, and a damper chamber DC. The supply flow channel  41 C includes a common supply flow channel provided in common for a plurality of pressure chambers C. The common supply flow channel includes the flow channel  45 A, the flow channel  46 A, the communication flow channel  47 D, and the damper chamber DC. 
     The discharge flow channel  41 D includes communication flow channels  47 C, a communication flow channel  47 E, a damper chamber DD, a flow channel  46 B, and a flow channel  45 B. The discharge flow channel  41 D includes individual discharge flow channels provided respectively for the plurality of pressure chambers C. The individual discharge flow channels include the plurality of communication flow channels  47 C. The discharge flow channel  41 D includes a common discharge flow channel provided in common for the plurality of pressure chambers C. The common discharge flow channel includes the flow channel  45 B, the flow channel  46 B, the communication flow channels  47 C, the communication flow channel  47 E, and the damper chamber DD. 
     As illustrated in  FIG.  12   , in the communication plate  24 B, there are formed the flow channel  46 A, which is a part of a common liquid chamber RA, the communication flow channel  47 D, the plurality of communication flow channels  47 C, the communication flow channels  47 E, and the flow channel  46 B, which is a part of a common liquid chamber RB. Through-holes, grooves, recesses, and the like are formed in the communication plate  24 . These through-holes, grooves, recesses, and the like form part of the common liquid chambers RA and RB and the communication flow channels  47 D,  47 C, and  47 E. 
     As illustrated in  FIG.  13   , in the pressure chamber substrate  25 B, there are formed the flow channel  45 A, which is a part of the common liquid chamber RA, the damper chamber DC, the plurality of pressure chambers C, the damper chamber DD, and the flow channel  45 B, which is a part of the common liquid chamber RB. A plurality of nozzles N are illustrated with dashed lines in  FIG.  13   . 
     The supply-side damper chamber DC is provided in common for the plurality of pressure chambers C. The damper chamber DC extends in the Y-axis direction. The damper chamber DC communicates with the plurality of pressure chambers C. The discharge-side damper chamber DD is provided in common for the plurality of pressure chambers C. The damper chamber DD extends in the Y-axis direction. The damper chamber DD communicates with the plurality of pressure chambers C through the plurality of communication flow channels  47 C. 
     A length LX3 of the supply-side damper chamber DC in the X-axis direction is different from a length LX4 of the discharge-side damper chamber DB in the X-axis direction. The length LX3 of the supply-side damper chamber DC in the X-axis direction is longer than the length LX4 of the discharge-side damper chamber DD in the X-axis direction. The width of the damper chamber DC in the Y-axis direction is equal to the width of the damper chamber DD in the Y-axis direction. 
     In the liquid ejecting head  10 B according to Embodiment  2 , the supply-side compliance substrate  23 C is provided in common for the plurality of pressure chambers C. In the liquid ejecting head  10 B, the discharge-side compliance substrate  23 D is provided in common for the plurality of pressure chambers C. The configuration of the liquid ejecting head  10 B may be such that it includes such compliance substrates  23 C and  23 D. 
     Embodiment 3 
     Next, a liquid ejecting head  10 C according to Embodiment  3  will be described.  FIG.  14    is a cross-sectional view illustrating the liquid ejecting head  10 C  according to Embodiment  3 .  FIG.  15    is a cross-sectional view illustrating part of a supply-side vibration absorbing unit  70 E according to Embodiment  3 .  FIG.  16    is a cross-sectional view illustrating part of a discharge-side vibration absorbing unit  70 F according to Embodiment  3 . The liquid ejecting head  10 C according to Embodiment  3  differs from the liquid ejecting head  10  according to Embodiment  1  illustrated in  FIG.  2    in that the former includes the vibration absorbing unit  70 E in place of the vibration absorbing unit  70 A and the vibration absorbing unit  70 F in place of the vibration absorbing unit  70 B. The description of Embodiment  3  may omit descriptions similar to those in Embodiments  1  and  2 . 
     As illustrated in  FIG.  15   , the supply-side vibration absorbing unit  70 E includes compliance substrates  23 E and a thin gold film  71 E. The compliance substrates  23 E each include a flexible film. The compliance substrates  23 E each include an elastic layer  23   e  and an insulating layer  23   f . The elastic layer  23   e  is made of silicon dioxide (SiO 2 ), for example. The insulating layer  23   f  is made of zirconium dioxide (ZrO 2 ), for example. The elastic layer  23   e  is formed on a pressure chamber substrate  25 , and the insulating layer  23   f  is formed on the elastic layer  23   e . The elastic layer  23   e  is formed so as to be continuous with an elastic layer  26   a  of a vibration plate  26  covering pressure chambers C. The insulating layer  23   f  is formed so as to be continuous with an insulating layer  26   b  of the vibration plate  26 . 
     The plurality of compliance substrates  23 E are provided respectively for a plurality of damper chambers DA arrayed in the Y-axis direction. The compliance substrates  23 E are deformable under a pressure from the ink. The compliance substrates  23 E can absorb variations in the pressure on the ink in the damper chambers DA by deforming under the pressure from the ink. The plurality of compliance substrates  23 E individually deform for the plurality of damper chambers DA. 
     The thin gold film  71 E is formed on the compliance substrates  23 E. The thin gold film  71 E has a predetermined length in the X-axis direction. The length of the thin gold film  71 E in the X-axis direction is shorter than the length of the damper chambers DA in the X-axis direction. The thin gold film  71 E has a predetermined length in the Y-axis direction. The thin gold film  71 E is formed so as to cover the plurality of compliance substrates  23 E, which are arrayed in the Y-axis direction. The thin gold film  71 E may be provided individually for the plurality of compliance substrates  23 E. The thin gold film  71 E is formed from gold. It is preferable that the thickness of the thin gold film  71 E be large to a certain extent in order to reinforce the strength of the compliance substrates  23 E but be small to a certain extent in order to efficiently absorb variations in the pressure on the ink in the damper chambers DA. Experiments showed that the above two advantageous effects could be suitably achieved when the thickness was 0.7 to 1.3 µm. The vibration absorbing unit  70 E may include a thin metal film formed from a metal other than gold, e.g., tin, copper, or aluminum, in place of the thin gold film  71 E. 
     As illustrated in  FIG.  16   , the discharge-side vibration absorbing unit  70 F includes compliance substrates  23 F and a thin gold film  71 F. The compliance substrates  23 F each include a flexible film. The compliance substrates  23 F each include an elastic layer  23   g  and an insulating layer  23   h . The elastic layer  23   g  is made of silicon dioxide (SiO 2 ), for example. The insulating layer  23   h  is made of zirconium dioxide (ZrO 2 ), for example. The elastic layer  23   g  is formed on the pressure chamber substrate  25 , and the insulating layer  23   h  is formed on the elastic layer  23   g . The elastic layer  23   g  is formed so as to be continuous with the elastic layer  26   a  of the vibration plate  26  covering the pressure chambers C. The insulating layer  23   h  is formed so as to be continuous with the insulating layer  26   b  of the vibration plate  26 . 
     The plurality of compliance substrates  23 F are provided respectively for a plurality of damper chambers DB arrayed in the Y-axis direction. The compliance substrates  23 F are deformable under a pressure from the ink. The compliance substrates  23 F can absorb variations in the pressure on the ink in the damper chambers DB by deforming under the pressure from the ink. The plurality of compliance substrates  23 F individually deform for the plurality of damper chambers DB. 
     The thin gold film  71 F is formed on the compliance substrates  23 F. The thin gold film  71 F has a predetermined length in the X-axis direction. The length of the thin gold film  71 F in the X-axis direction is shorter than the length of the damper chambers DB in the X-axis direction. The thin gold film  71 F has a predetermined length in the Y-axis direction. The thin gold film  71 F is formed so as to cover the plurality of compliance substrates  23 F, which are arrayed in the Y-axis direction. The thin gold film  71 F may be provided individually for the plurality of compliance substrates  23 F. The thin gold film  71 F is formed from gold. It is preferable that the thickness of the thin gold film  71 F be large to a certain extent in order to reinforce the strength of the compliance substrates  23 F but be small to a certain extent in order to efficiently absorb variations in the pressure on the ink in the damper chambers DB. Experiments showed that the above two advantageous effects could be suitably achieved when the thickness was 0.7 to 1.3 µm. The vibration absorbing unit  70 F may include a thin metal film formed from a metal other than gold, e.g., tin, copper, or aluminum, in place of the thin gold film  71 F. 
     As described above, the liquid ejecting head  10 C may include the thin gold film  71 E formed on the compliance substrates  23 E. The liquid ejecting head  10 C may include the thin gold film  71 F formed on the compliance substrates  23 F. Since the thin gold films  71 E and  71 F are formed on the compliance substrates  23 E and  23 F in the liquid ejecting head  10 C, the strength of the compliance substrates  23 E and  23 F is reinforced. This improves the reliability of the compliance substrates  23 E and  23 F. 
     Here, the ease of deformation of the compliance substrates  23 E and  23 F can be changed by changing the thickness of the thin gold films  71 E and  71 F. The efficiency of vibration absorption by the vibration absorbing units  70 E and  70 F may be changed by changing the thickness of the thin gold films  71 E and  71 F. The ease of deformation of the compliance substrates  23 E and  23 F may be changed by changing the material of the thin metal films on the compliance substrates  23 E and  23 F. 
     Embodiment 4 
     Next, a liquid ejecting head  10  according to Embodiment  4  will be described. Illustration of the liquid ejecting head  10  according to Embodiment  4  is omitted. Cross-sectional views of the liquid ejecting head  10  according to Embodiment  4  are substantially the same as the cross-sectional views of the liquid ejecting head  10 C according to Embodiment  3  illustrated in  FIGS.  14  to  16   . The liquid ejecting head  10  according to Embodiment  4  differs from the liquid ejecting head  10 C according to Embodiment  3  illustrated in  FIG.  14    in that the former includes damper chambers DC and DD in place of the damper chambers DA and DB and communication flow channels  47 D and  47 E in place of the communication flow channels  47 A and  47 B. The damper chambers DC and DD and the communication flow channels  47 D and  47 E are the same as the damper chambers DC and DD and the communication flow channels  47 D and  47 E in Embodiment  2  illustrated in  FIG.  11   . 
     In the liquid ejecting head  10  according to Embodiment  4 , a thin gold film  71 E is formed on a compliance substrate  23 C covering the damper chamber DC, which is a common supply flow channel. In the liquid ejecting head  10  according to Embodiment  4 , a thin gold film  71 F is formed on a compliance substrate  23 D covering the damper chamber DD, which is a common discharge flow channel. The thin gold films  71 E and  71 F can be formed similarly to the thin gold films  71 E and  71 F in Embodiment  3  described above. 
     Embodiment 5 
     Next, a liquid ejecting head  10 E according to Embodiment  5  will be described. A cross-sectional view of the liquid ejecting head  10 E according to Embodiment  5  is substantially the same as the cross-sectional view of the liquid ejecting head  10  according to Embodiment  1  illustrated in  FIG.  2   . The liquid ejecting head  10 E according to Embodiment  5  differs from the liquid ejecting head  10  according to Embodiment  1  illustrated in  FIG.  2    in that the former includes a damper chamber DC in place of the damper chambers DA, a communication flow channel  47 D in place of the communication flow channels  47 A, and a vibration absorbing unit  70 C in place of the vibration absorbing unit  70 A. The damper chamber DC, the communication flow channel  47 D, and the vibration absorbing unit  70 C are the same as the damper chamber DC, the communication flow channel  47 D, and the vibration absorbing unit  70 C in Embodiment  2  illustrated in  FIG.  11   . 
       FIG.  17    is a plan view illustrating part of a communication plate  24 E of the liquid ejecting head  10 E according to Embodiment  5 . The liquid ejecting head  10 E includes the communication plate  24 E in place of the communication plate  24  in Embodiment  1 . In the communication plate  24 E, there are formed the communication flow channel  47 D included in a common supply flow channel and communication flow channels  47 B included in individual discharge flow channels. 
       FIG.  18    is a plan view illustrating part of a pressure chamber substrate  25 E of the liquid ejecting head  10 E according to Embodiment  5 . The liquid ejecting head  10 E includes the pressure chamber substrate  25 E in place of the pressure chamber substrate  25  in Embodiment  1 . In the pressure chamber substrate  25 E, there are formed the damper chamber DC included in the common supply flow channel and damper chambers DB included in the individual discharge flow channels. 
     As described above, in the liquid ejecting head  10 E, the supply-side damper chamber DC is provided in common for a plurality of pressure chambers C, and the discharge-side damper chambers DB are provided individually and respectively for the plurality of pressure chambers C. In the liquid ejecting head  10 E, a compliance substrate  23 C is provided in common for the plurality of pressure chambers C. In the liquid ejecting head  10 E, compliance substrates  23 B are provided respectively for the plurality of pressure chambers C. In the liquid ejecting head  10 E, the compliance substrates  23 B are provided individually for the plurality of pressure chambers C. 
     Embodiment 6 
     Next, a liquid ejecting head  10  according to Embodiment  6  will be described. Illustration of the liquid ejecting head  10  according to Embodiment  6  is omitted. A cross-sectional view of the liquid ejecting head  10  according to Embodiment  6  is substantially the same as the cross-sectional view of the liquid ejecting head  10 C according to Embodiment  3  illustrated in  FIG.  14   . The liquid ejecting head  10  according to Embodiment  6  differs from the liquid ejecting head  10 C according to Embodiment  3  illustrated in  FIG.  14    in that the former includes a damper chamber DC in place of the damper chambers DA and a communication flow channel  47 D in place of the communication flow channels  47 A. The damper chamber DC, the communication flow channel  47 D, and a vibration absorbing unit  70 C are the same as the damper chamber DC, the communication flow channel  47 D, and the vibration absorbing unit  70 C in Embodiment  2  illustrated in  FIG.  11   . 
     The communication plate in Embodiment  6  is the same as the communication plate  24 E in Embodiment  5  illustrated in  FIG.  17   . The pressure chamber substrate in Embodiment  6  is the same as the pressure chamber substrate  25 E in Embodiment  5  illustrated in  FIG.  18   . 
     The liquid ejecting head  10  according to Embodiment  6  includes a supply-side vibration absorbing unit  70 E and a discharge-side vibration absorbing unit  70 F. A cross-sectional view of the supply-side vibration absorbing unit  70 E is substantially the same as that of the vibration absorbing unit  70 E illustrated in  FIG.  15   . In Embodiment  6 , compliance substrates  23 E are provided. The compliance substrates  23 E are provided for the damper chamber DC, which is a common supply flow channel. The supply-side vibration absorbing unit  70 E includes the compliance substrates  23 E provided for the common damper chamber DC, and a thin gold film  71 E provided on these compliance substrates  23 E. 
     A cross-sectional view of the supply-side vibration absorbing unit  70 F is the same as that of the vibration absorbing unit  70 F illustrated in  FIG.  16   . In Embodiment  6 , compliance substrates  23 F are provided. The compliance substrates  23 F are provided for damper chambers DB, which are individual discharge flow channels. The discharge-side vibration absorbing unit  70 F includes a plurality of compliance substrates  23 F provided respectively for the plurality of damper chambers DB, and a thin gold film  71 F provided on these compliance substrates  23 F. 
     In the liquid ejecting head  10  according to Embodiment  6 , the thin gold films  71 E and  71 F are provided on the compliance substrates  23 E and  23 F. 
     Embodiment 7 
     Next, a liquid ejecting head  10  according to Embodiment  7  will be described. Illustration of the liquid ejecting head  10  according to Embodiment  7  is omitted. A cross-sectional view of the liquid ejecting head  10  according to Embodiment  7  is substantially the same as the cross-sectional view of the liquid ejecting head  10 B according to Embodiment  2  illustrated in  FIG.  11   . The liquid ejecting head  10  according to Embodiment  7  differs from the liquid ejecting head  10 B according to Embodiment  2  illustrated in  FIG.  11    in that the former includes a vibration absorbing unit  70 E in place of the vibration absorbing unit  70 C. In Embodiment  7 , the supply-side vibration absorbing unit  70 E has a thin gold film  71 E, and a discharge-side vibration absorbing unit  70 D has piezoelectric elements  71 D. 
     In Embodiment  7 , the structure provided on a supply-side compliance substrate  23 C and the structure provided on a discharge-side compliance substrate  23 D are different. Making the structures on the compliance substrates  23 C and  23 D different as above can provide a difference between the vibration absorption performance on the supply side and the vibration absorption performance on the discharge side. 
     For example, as a modification of Embodiment  7 , piezoelectric elements  71 A may be provided on the supply-side compliance substrate  23 C, and a thin gold film  71 F may be provided on the discharge-side compliance substrate  23 D. In the liquid ejecting heads  10  according to the other embodiments too, the structures on the supply-side and discharge-side compliance substrates may be different. 
     Embodiment 8 
     Next, a liquid ejecting head  10 H according to Embodiment  8  will be described.  FIG.  19    is a cross-sectional view illustrating the liquid ejecting head  10 H according to Embodiment  8 . The liquid ejecting head  10 H according to Embodiment  8  illustrated in  FIG.  19    differs from the liquid ejecting head  10  according to Embodiment  1  illustrated in  FIG.  2    in that the flow direction of the liquid is different. The flow direction of the liquid in the liquid ejecting head  10 H according to Embodiment  8  is the reverse of the flow direction of the liquid in the liquid ejecting head  10  according to Embodiment  1 . In  FIG.  19   , the flow direction of the liquid is indicated by arrows. In  FIG.  19   , most of the reference signs shown are the same as those in  FIG.  1   , but the flow direction of the liquid is the reverse of that in  FIG.  1   . The description of the liquid ejecting head  10 H according to Embodiment  8  may omit descriptions similar to those of the liquid ejecting heads  10  according to Embodiments  1  to  7  given above. 
     In the liquid ejecting head  10 H, a flow channel  40 H through which the ink flows is formed. The flow channel  40 H includes a supply port  42 C, a discharge port  42 D, common liquid chambers RA and RB, damper chambers DA and DB, pressure chambers C, communication flow channels  47 A to  47 C, and nozzles N. 
     The flow channel  40 H has a supply flow channel  41 E and a discharge flow channel  41 F. The supply flow channel  41 E is a flow channel upstream of the pressure chambers C, and is a flow channel inside a communication plate  24  and a pressure chamber substrate  25 . The supply flow channel  41 E includes a flow channel  45 B, a flow channel  46 B, communication flow channels  47 B, damper chambers DB, and communication flow channels  47 C. The discharge flow channel  41 F is a flow channel downstream of the pressure chambers C, and is a flow channel inside the communication plate  24  and the pressure chamber substrate  25 . The discharge flow channel  41 F includes damper chambers DA, communication flow channels  47 A, a flow channel  46 A, and a flow channel  45 A. 
     The liquid ejecting head  10 H includes the supply-side damper chambers DB and the discharge-side damper chambers DA. The liquid ejecting head  10 H includes a supply-side vibration absorbing unit  70 B and a discharge-side vibration absorbing unit  70 A. In this case, compliance substrates  23 B are supply-side compliance substrates. The compliance substrates  23 A are discharge-side compliance substrates. 
     In Embodiment  8 , a length LX12 of the discharge-side compliance substrates  23 A in the X-axis direction is longer than a length LX11 of the supply-side compliance substrates  23 B in the X-axis direction. 
     As mentioned above, a length LX12 of the discharge-side compliance substrates  23 A in the X-axis direction may be longer than a length LX11 of the supply-side compliance substrates  23 B in the X-axis direction. 
     In Embodiment  8 , the compliability of the discharge-side compliance substrates  23 A is higher than the compliability of the supply-side compliance substrates  23 B. The compliance substrates  23 A and  23 B are made of the same material and have the same thickness. The compliability of the compliance substrates  23 A is higher than the compliability of the compliance substrates  23 B since the length LX12 of the compliance substrates  23 A in the X-axis direction is longer than the length LX11 of the compliance substrates  23 B in the X-axis direction. 
     In Embodiment  8 , the inertance of the discharge flow channel  41 F is higher than the inertance of the supply flow channel  41 E. In Embodiment  8 , the compliability of each of the compliance substrates  23 A and  23 B is set according to the magnitude of its inertance. 
     Liquid Ejecting Apparatus 
     Next, a liquid ejecting apparatus  1  including a liquid ejecting head  10  will be described with reference to  FIGS.  20  and  21   .  FIG.  20    is a schematic diagram illustrating the liquid ejecting apparatus  1  including a liquid ejecting head  10 . The liquid ejecting apparatus  1   includes the liquid ejecting head  10  according to Embodiment  1  described above.  FIG.  21    is a block diagram illustrating the liquid ejecting apparatus  1 . The liquid ejecting apparatus  1  is not limited to the configuration including the liquid ejecting head  10  according to Embodiment  1 . The liquid ejecting apparatus  1  may include any of the liquid ejecting heads  10 B to  10 G according to Embodiments  2  to  7  in place of the liquid ejecting head  10  according to Embodiment  1 . 
     The liquid ejecting apparatus  1  is an ink jet printing apparatus that ejects an ink, which is an example of “liquid”, in the form of droplets onto a medium PA. The liquid ejecting apparatus  1  is a serial-type printing apparatus. The medium PA is typically print paper. The medium PA is not limited to print paper and may be a printing target of any material such as a resin film or a woven fabric, for example. 
     The liquid ejecting apparatus  1  includes the liquid ejecting head  10 , which ejects the ink, a liquid container  2  which stores the ink, a carriage  3  which carries the liquid ejecting head  10 , a carriage transporting mechanism  4  which transports the carriage  3 , a medium transporting mechanism  5  which transports the medium PA, and a control unit  30 . The control unit  30  is a control unit which controls the liquid ejection. 
     Examples of specific forms of the liquid container  2  include a cartridge detachably attachable to the liquid ejecting apparatus  1 , a bag-shaped ink pack formed from a flexible film, and an ink tank that can be filled with an ink. The liquid container  2  may store any type of ink. In an example, the liquid ejecting apparatus  1  includes a plurality of liquid containers  2  for inks of four colors. Examples of the inks of the 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 a circulating mechanism  8  which circulates the ink. The circulating mechanism  8  includes a supply flow channel  81  through which the ink is supplied to the liquid ejecting head  10 , a collection flow channel  82  through which the ink discharged from the liquid ejecting head  10  is collected, and a pump  83  which sends the ink. 
     The carriage transporting mechanism  4  has a transporting belt  4   a  and a motor for transporting the carriage  3 . The medium transporting mechanism  5  has a transporting roller  5   a  and a motor for transporting the medium PA. The carriage transporting mechanism  4  and the medium transporting mechanism  5  are controlled by the control unit  30 . While transporting the medium PA with the medium transporting mechanism  5  and at the same time transporting the carriage  3  with the carriage transporting mechanism  4 , the liquid ejecting apparatus  1  ejects ink droplets onto the medium PA to perform printing. 
     As illustrated in  FIG.  21   , the liquid ejecting apparatus  1  includes a linear encoder  6 . The linear encoder  6  is provided at such a position as to be capable of detecting the position of the carriage  3 . The linear encoder  6  obtains information on the position of the carriage  3 . As the carriage  3  moves, the linear encoder  6  outputs an encoder signal to the control unit  30 . 
     The control unit  30  includes one or more CPUs  31 . The control unit  30  may include an FPGA in place of the CPUs  31  or in addition to the CPUs  31 . The control unit  30  includes a storage unit  35 . The storage unit  35  includes, for example, a ROM  36  and a RAM  37 . The storage unit  35  may include an EEPROM or a PROM. The storage unit  35  is capable of storing print data Img supplied from a host computer. The storage unit  35  stores a program for controlling the liquid ejecting apparatus  1 . 
     CPU stands for Central Processing Unit. FPGA stands for Field-Programmable Gate Array. RAM stands for Random Access Memory. ROM stands for Read Only Memory. EEPROM stands for Electrically Erasable Programmable Read-Only Memory. PROM stands for Programmable ROM. 
     The control unit  30  generates signals for controlling the operations of components of the liquid ejecting apparatus  1 . The control unit  30  is capable of generating a print signal SI and a waveform designating signal dCom. The print signal SI is a digital signal for designating the type of operation of the liquid ejecting head  10 . The print signal SI can designate whether to supply a driving signal Com to the piezoelectric elements  50 . The waveform designating signal dCom is a digital signal that specifies the waveform of the driving signal Com. The driving signal Com is an analog signal for driving the piezoelectric elements  50 . 
     The liquid ejecting apparatus  1  includes a driving signal generating circuit  32 . The driving signal generating circuit  32  is electrically coupled to the control unit  30 . The driving signal generating circuit  32  includes a DA conversion circuit. The driving signal generating circuit  32  generates the driving signal Com having the waveform specified by the waveform designating signal dCom. In response to receiving an encoder signal from the linear encoder  6 , the control unit  30  outputs a timing signal PTS to the driving signal generating circuit  32 . The timing signal PTS specifies a timing to generate the driving signal Com. The driving signal generating circuit  32  generates the driving signal Com each time it receives the timing signal PTS. 
     The driving circuit  62  is electrically coupled to the control unit  30  and the driving signal generating circuit  32 . Based on the print signal SI, the driving circuit  62  switches to supplying or not supplying the driving signal Com to the piezoelectric elements  50 . The driving circuit  62  is capable of selecting the piezoelectric elements  50  to supply the driving signal Com based on the print signal SI, a latch signal LAT, and, a change signal CH supplied from the control unit  30 . The latch signal LAT specifies a latch timing for the print data Img. The change signal CH specifies timings to select driving pulses to be included in the driving signal Com. 
     The control unit  30  controls the ink ejection operation of liquid ejecting head  10 . By driving the piezoelectric elements  50  as described above, the control unit  30  changes the pressure on the ink in the pressure chambers C to eject the ink from the nozzles N. The control unit  30  controls the ejection operation when performing a printing operation. 
     In such a liquid ejecting apparatus  1 , the liquid ejecting head  10  described above can be used. In the liquid ejecting apparatus  1  including the liquid ejecting head  10 , the length LX1 of the supply-side compliance substrates  23 A in the X-axis direction is longer than the length LX2 of the discharge-side compliance substrates  23 B in the X-axis direction. Making the length LX2 of the discharge-side compliance substrates  23 B shorter than the length LX1 of the supply-side compliance substrates  23 A enables downsizing of the liquid ejecting head  10 . 
     The above-described embodiments merely illustrate representative forms of the present disclosure. The present disclosure is not limited to the above-described embodiments, and various changes and additions can be made without departing from the gist of the present disclosure. Modification  1   
     In the liquid ejecting head  10  according to Embodiment  1  described above, the compliance substrates  23 A and  23 B are provided at the same position in the Z-axis direction as the vibration plate  26 . However, the compliance substrates  23 A and  23 B may be provided at a different position in the Z-axis direction from the vibration plate  26 . For example, the supply-side compliance substrates  23 A may be provided on the Z1-direction side of the communication flow channels  47 A. The discharge-side compliance substrates  23 B may be provided on the Z1-direction side of the communication flow channels  47 B. The compliance substrates  23 A and  23 B may be provided at the nozzle substrate  21 . 
     Modification 2 
     The liquid ejecting head  10  according to Embodiment  1  described above has a configuration with the compliance substrates  77 A and  77 B provided in the common liquid chambers RA and RB. However, the liquid ejecting head  10  may have a configuration without the compliance substrates  77 A and  77 B. The compliance amount of the supply-side compliance substrate  77 A and the compliance amount of the discharge-side compliance substrate  77 B may be different. The compliance substrates  77 A and  77 B may have different sizes. 
     Modification 3 
     In the liquid ejecting head  10  according to Embodiment  1  described above, the COF  60  is disposed between the piezoelectric elements  50  and the discharge-side compliance substrates  23 B in the X-axis direction. However, the arrangement of the COF  60  is not limited to this one. For example, the COF  60  may be disposed between the piezoelectric elements  50  and the supply-side compliance substrates  23 A in the X-axis direction. 
     Modification 4 
     In the liquid ejecting head  10  according to Embodiment  1  described above, the nozzles N are disposed at positions overlapping the pressure chambers C as viewed from the Z-axis direction. However, the nozzles N may be disposed at positions not overlapping the pressure chambers C. Also, the configuration of the liquid ejecting head  10   may be such that a plurality of pressure chambers C communicate with a single nozzle N. 
     Modification 5 
     In the liquid ejecting head  10  according to Embodiment  1  described above, the vibration absorbing unit  70 A has a configuration in which it includes the individual electrode layers  71   a , the common electrode layer  71   b , and the piezoelectric layers  71   c  on the compliance substrates  23 A. However, the vibration absorbing unit  70 A is not limited to one including the individual electrode layers  71   a , the common electrode layer  71   b , and the piezoelectric layers  71   c . For example, the configuration of the vibration absorbing unit  70 A may be such that it includes the piezoelectric layers  71   c  and the common electrode layer  71   b  and does not include the individual electrode layers  71   a . A different thing may be disposed on the compliance substrates  23 A. When the things to be laminated onto the compliance substrates  23 A have the same configuration as the piezoelectric elements  50  on the vibration plate  26 , the individual electrode layers  71   a , the common electrode layer  71   b , and the piezoelectric layers  71   c  can be laminated onto the compliance substrates  23 A simultaneously with the lamination of the piezoelectric elements  50 . This enables easy manufacture of the piezoelectric elements  71 A on the compliance substrates  23 A. The same applies also to the piezoelectric elements  71 B on the compliance substrates  77 B. Modification  6   
     The rigidity of the supply-side compliance substrates  23 A may be lower than the rigidity of the discharge-side compliance substrates  23 B. For example, the compliance substrates  23 A and  23 B can be made different in rigidity by making their thicknesses, materials, lengths in the X-axis direction, lengths in the Y-axis direction, etc different. Also, the compliance substrates  23 A and  23 B can be made different in rigidity by making the configurations of the laminates on the compliance substrates  23 A and  23 B different. The laminates on the compliance substrates  23 A and  23 B include the piezoelectric elements  71 A and  71 B and the thin gold film  71 E described above, for example. 
     In one of the above-described embodiments, the serial-type liquid ejecting apparatus  1 , which moves the carriage  3  carrying a liquid ejecting head  10  back and forth in the width direction of the medium PA, has been exemplarily described. The present disclosure may be applied to a line-type liquid ejecting apparatus including a line head being a plurality of liquid ejecting heads  10  arrayed in a predetermined direction. 
     The liquid ejecting apparatus  1  exemplarily described in one of the above-described embodiments can be employed in various machines such as facsimiles and photocopiers as well as machines dedicated for printing. Nonetheless, the application of the liquid ejecting apparatus of the present disclosure is not limited to printing. For example, a liquid ejecting apparatus that ejects a solution of a colorant may be utilized as a manufacturing apparatus that forms a color filter of a display apparatus, such as a liquid crystal display panel. A liquid ejecting apparatus that ejects a solution of an electrically conductive material may be utilized as a manufacturing apparatus that forms wirings or electrodes of a wiring substrate. A liquid ejecting apparatus that ejects a solution of a biological organic substance may be utilized as a manufacturing apparatus that manufactures a biochip, for example.