JP4915381B2 - Droplet discharge device and droplet discharge head - Google Patents

Description

  The present invention relates to a droplet discharge device such as an inkjet printer and a droplet discharge head such as an inkjet head.

  Conventionally, as one of the droplet discharge devices, an inkjet head in which a piezoelectric actuator for selectively discharging ink in each pressure chamber is joined to a cavity unit in which a plurality of pressure chambers are regularly formed; There is known an ink jet printer provided with a voltage applying means for applying a voltage to the piezoelectric actuator. As piezoelectric actuators as described above, there are known ones using a stacked vertical effect actuator (for example, see Patent Document 1) and those using a unimorph actuator (for example, see Patent Document 2).

  In the ink jet head of such an ink jet printer, there is a demand for high density pressure chambers in order to increase the number of nozzles and ensure high image quality and high quality of recording. When the pressure chambers are arranged in high density, the distance between the adjacent pressure chambers is shortened, so that an influence on the adjacent pressure chambers, that is, a so-called crosstalk problem occurs during driving.

  That is, in the inkjet head, for example, as shown in FIGS. 39 and 40, the piezoelectric actuator 112 including three piezoelectric material layers 112a, 112b, and 112c is disposed above the cavity unit 114 in which the pressure chambers 114a are regularly formed. It is joined via a restraining plate 115. An individual electrode 121 is provided on the upper surface side of the piezoelectric material layer 112a corresponding to each pressure chamber 114a, a constant potential electrode 122 (ground potential) is provided on the lower surface side, and an upper surface side of the piezoelectric material layer 112c. The individual electrode 121 is provided on the lower surface side, and the constant potential electrode 122 is provided on the lower surface side. With such a configuration, a region (piezoelectric material layer) sandwiched between the individual electrode 121 and the constant potential electrode 122 selectively applies a positive potential to the individual electrode 121, thereby increasing the volume of the pressure chamber 114a. It functions as an active portion S that changes and ejects ink from the nozzle hole 114b. Such deformation for ink ejection is not only applied to the pressure chamber for ejecting ink, but also to the pressure chamber 114a adjacent to the pressure chamber 114a due to the deformation of the piezoelectric material layers 112a to 112c as shown in FIG. Affect.

  For this reason, there is a problem that the discharge characteristics fluctuate between adjacent pressure chambers 114 (for example, a problem that unintended ink is discharged from the nozzle hole 114b), that is, a problem of crosstalk.

  Various measures have been proposed to solve such a crosstalk problem. For example, in Patent Document 3, the rigidity of the partition wall 11 is improved by providing the beam portions 100 between the partition walls 11 on both sides in the width direction of the pressure generation chamber 12, and crosstalk occurs between the adjacent pressure generation chambers. What has been prevented from occurring is described.

Further, in Patent Document 4, an elastic body 7 having a predetermined depth and a predetermined width from the nozzle plate 3 is disposed on the side wall 5 that separates the pressurized liquid chambers 4 so as to reduce mechanical crosstalk. What is made is described.
JP 2005-59551 A JP 2005-317952 A JP 2002-254640 A (FIG. 2) Japanese Patent Laid-Open No. 2002-19113 (FIG. 1)

  However, these measures are not perfect as the pressure chambers (ink ejection channels) are increased in density.

  An object of the present invention is to provide a droplet discharge device and a droplet discharge head that can suppress crosstalk without increasing the number of individual electrodes, that is, the number of signal lines, even if the density is increased. .

  According to a first aspect of the present invention, there is provided a droplet discharge head in which a piezoelectric actuator for selectively discharging a liquid in each pressure chamber is joined to a cavity unit in which a plurality of pressure chambers are regularly formed, and the piezoelectric actuator And a voltage applying means for applying a voltage to the piezoelectric actuator, wherein the piezoelectric actuator includes a first active portion corresponding to a central portion of the pressure chamber and a central portion of the pressure chamber. A second active portion corresponding to a portion on the outer peripheral side, and each of the first active portion and the second active portion is provided in the pressure chamber when a voltage is applied by the voltage applying means. The voltage applying means applies a voltage to the first active portion. The voltage applying means applies a voltage to the first active portion. when While not applied serial second voltage to the active portion, and wherein the time of not applying voltage to the first active portion is to apply a voltage to the second active portion. Here, the “active part” means a part that becomes a deformed state or a non-deformed state when a voltage is applied or not. In addition to the case where the “second active part” exists across the part corresponding to the pressure chamber and the part corresponding to the girder part between the pressure chambers, The case where it exists only in the corresponding part and the case where it exists only in the part corresponding to the pressure chamber are included. The “first direction” means the direction in which the pressure chamber and the active part are arranged, that is, the stacking direction of the piezoelectric actuator and the cavity unit.

  In this way, the first active portion corresponding to the central portion of the pressure chamber and the second active portion corresponding to the outer peripheral portion of the pressure chamber are applied / non-applied with voltage. Therefore, even if the pressure chambers are densified and the adjacent pressure chambers come closer to each other, the deformation of the first active portion is transmitted to the adjacent pressure chambers. At this time, the so-called crosstalk, which is canceled by the deformation of the second active portion and the deformation of the first active portion propagates to the adjacent pressure chamber, is suppressed.

  In this case, as described in claim 2, in the droplet discharge device of claim 1, it is preferable that the second active portion includes a region inside the outer peripheral edge of the pressure chamber.

  In this way, not only the first active part but also the second active part contributes to the volume change of the pressure chamber, and the volume of the pressure chamber is changed more greatly than in the case of using only the first active part. be able to. Therefore, it is possible to improve the discharge efficiency (discharge amount when the voltage is applied) for selectively discharging the liquid in the pressure chamber by applying a voltage to the piezoelectric actuator.

  According to a third aspect of the present invention, in the liquid droplet ejection apparatus according to the first or second aspect, the first active portion includes an individual electrode to which a first potential and a second potential different from the first potential are selectively applied. And a piezoelectric material sandwiched between the first constant potential electrode to which the first potential is applied, and the second active portion includes the individual electrode and the second potential. Can be configured to include a piezoelectric material sandwiched between the second constant potential electrode to which is applied.

  In this way, the first active portion and the second active portion can be deformed (return to the original state) only by selectively applying the first potential and the second potential to the individual electrode. ) At the same time. Therefore, the deformation of the first active part that is about to propagate to the adjacent pressure chamber is canceled by the deformation of the second active part, and crosstalk is suppressed without requiring highly precise timing control.

  5. The liquid droplet ejection apparatus according to claim 1, wherein the individual electrode includes a region corresponding to the first active portion and a region corresponding to the second active portion. The first constant potential electrode is formed so as to occupy a region corresponding to the first active part, and the second constant potential electrode is at least It is desirable to form so as to occupy a region corresponding to the second active portion.

  If it does in this way, the arrangement | positioning without a waste will be attained by arrange | positioning an electrode efficiently for implement | achieving the structure of Claims 1-3.

  According to a fifth aspect of the present invention, in the droplet discharge device according to the third or fourth aspect, the first active portion is configured such that the second potential is applied to the individual electrode and the first constant potential electrode is the first first potential. The second active portion is polarized in the same direction as the voltage applied when the second potential is applied, and the second constant potential electrode is applied with the first potential applied to the individual electrode. The second electrode can be polarized in the same direction as the voltage applied when the second potential is applied.

  In this way, in the first and second active portions, the voltage application direction during driving and the voltage application direction during polarization can all be aligned, and the electrode can be driven (when the active portion is deformed). In addition, it can be used for polarization during manufacturing. In addition, since the voltage application direction during driving is the same as the voltage application direction during polarization (polarization direction), and no reverse electric field is applied to the piezoelectric material layer during driving, deformation of the active portion is prevented from being deteriorated. .

  In the case of the droplet discharge device according to any one of claims 3 to 5, as described in claim 6, the first potential is a positive potential and the second potential is a ground potential. Conversely, as described in claim 7, the first potential may be a ground potential, and the second potential may be a positive potential.

  In this way, drive control can be easily performed by selectively applying two types of potentials, a positive potential and a ground potential, to each individual electrode.

  As described in claim 8, in the droplet discharge device according to claim 7, it is desirable that the second constant potential electrode is shared with the adjacent pressure chamber.

  In this way, the number of second constant potential electrodes can be reduced to simplify the whole electrode.

  9. The droplet discharge device according to claim 7, wherein the piezoelectric actuator has at least one piezoelectric material layer, and the individual electrode is provided on one surface side of the piezoelectric material layer. And forming the first constant potential electrode and the second constant potential electrode on the other surface side so that the first active portion and the second active portion are formed on the same piezoelectric material layer. It can be set as the structure to form. Here, the “piezoelectric material layer” includes not only a piezoelectric sheet manufactured by firing a so-called green sheet but also a material manufactured by a manufacturing method such as a so-called AD method (aerosol deposition method).

In this way, the arrangement of the necessary electrodes can be realized only by having at least one piezoelectric material layer, which is advantageous in terms of material cost.

  11. The droplet discharge device according to claim 9, wherein the first constant potential electrode and the second constant potential electrode formed on the other surface side are the piezoelectric material layer. It can be set as the structure isolated on both sides of the thinner insulating layer.

  In this way, the first constant potential electrode and the second constant potential electrode are separated from each other with the insulating layer interposed therebetween, so that the first constant potential electrode and the second constant potential electrode are formed close to each other. Even so, they do not short. Therefore, the first active part and the second active part can be arranged close to each other, which is advantageous in reducing the size.

  As described in claim 11, in the droplet discharge device according to claim 10, the insulating layer can be made of the same material as the piezoelectric material layer.

  In this case, since the insulating layer uses the same material as the piezoelectric material layer, manufacturing is simple and advantageous in terms of cost.

  According to a twelfth aspect of the present invention, in the droplet discharge device according to the seventh aspect, the first constant potential electrode is formed so as to form a row with the two adjacent pressure chambers. The second constant potential electrode may be formed only on one side of the two pressure chambers.

  In this way, the second active portion is arranged on one side of the pressure chamber, and crosstalk is suppressed only on the one side.

  According to a thirteenth aspect of the present invention, in the droplet discharge device according to any one of the third to fifth aspects, the piezoelectric actuator includes a plurality of piezoelectric material layers, and the first constant potential electrode or the second constant potential electrode. A constant potential electrode is formed on a farthest surface, which is a surface opposite to the pressure chamber, of the farthest layer positioned farthest from the pressure chamber of the plurality of piezoelectric material layers, and the individual electrodes are Each piezoelectric material layer is formed on a surface different from the most distant surface and is formed on a region outside the outer peripheral edge of the pressure chamber of the most distant surface. A surface electrode serving as an input terminal is formed, and the individual electrode may be electrically connected to the surface electrode through a through hole penetrating the piezoelectric material layer.

  In this way, when there are a plurality of piezoelectric material layers, it is possible to achieve a reasonable arrangement of individual electrodes using surface electrodes and through holes.

  The liquid droplet ejection apparatus according to claim 14, wherein the second active portion is formed in a layer other than the most separated layer of the plurality of piezoelectric material layers, The surface electrode can be configured to be formed in a region between the adjacent pressure chambers.

  In this way, since the surface electrode is formed in the region between the adjacent pressure chambers without buffering with the second active portion, the freedom of the position for forming the surface electrode is improved.

According to a fifteenth aspect of the present invention, there is provided a droplet discharge head in which a piezoelectric actuator for selectively discharging a liquid in each pressure chamber is joined to a cavity unit in which a plurality of pressure chambers are regularly formed; A voltage applying means for applying to the actuator, wherein the piezoelectric actuator includes a first portion located corresponding to a central portion of the pressure chamber, and the central portion of the pressure chamber. And a second portion positioned corresponding to the outer peripheral portion, and the voltage application means switches between applying and not applying a voltage to the first portion in order to change the volume of the pressure chamber. together, so as to suppress the propagation of the pressure chamber deformation of the first portion by the switching adjacent switches the application and non-application of a voltage to the second portion It When applying a voltage to the first portion while no voltage is applied to the second portion, when no voltage is applied to said first portion is to apply a voltage to the second portion It is characterized by.

  In this case, in order to change the volume of the pressure chamber, switching between application and non-application of voltage to the first portion is performed, and the deformation of the first portion due to this switching is propagated to the adjacent pressure chamber. Since the application of the voltage to the second portion is switched to the non-application so as to suppress, the crosstalk is suppressed.

The invention according to claim 16 is a droplet discharge head in which a piezoelectric actuator for selectively discharging a liquid in each pressure chamber is joined to a cavity unit in which a plurality of pressure chambers are regularly formed. The piezoelectric actuator includes a first active portion corresponding to a central portion of the pressure chamber, a second active portion corresponding to a portion on the outer peripheral side of the central portion of the pressure chamber, and the first active portion. An individual electrode which is formed so as to occupy the corresponding region and the region corresponding to the second active portion together and is selectively applied with a first potential and a second potential different from the first potential ;
A first constant potential electrode formed to occupy a region corresponding to the first active portion and to which the first potential is applied;
And a second constant potential electrode formed to occupy at least a region corresponding to the second active portion and to which a second potential different from the first potential is applied.

  In this way, the first active portion corresponding to the central portion of the pressure chamber and the second active portion corresponding to the outer peripheral portion of the pressure chamber are applied / non-applied with voltage. Since it can be set as the structure which a deformation | transformation of a reverse direction produces by application, the crosstalk which the deformation | transformation of a 1st active part propagates to the adjacent pressure chamber is suppressed.

  According to the present invention, the first active portion corresponding to the central portion of the pressure chamber and the second active portion corresponding to the outer peripheral side portion of the pressure chamber are applied or not applied with voltage. Since the deformation in the reverse direction occurs, even if the pressure chambers are densified, the crosstalk in which the deformation of the active portion propagates to the adjacent pressure chambers can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Example 1
FIG. 1A is a schematic configuration diagram showing a schematic configuration of an ink jet printer (droplet discharge device) according to the present invention, and FIG. 1B is a diagram of a cavity unit, a piezoelectric actuator and a flexible wiring board (COP) according to the present invention. It is explanatory drawing which shows a relationship.

  As shown in FIG. 1A, an inkjet printer 1 according to the present invention has an inkjet head for recording on a recording sheet P (recording medium) on a lower surface of a carriage 2 on which an ink cartridge (not shown) is mounted. 3 (droplet discharge head) is provided. The carriage 2 is supported by a carriage shaft 5 and a guide plate (not shown) provided in the printer frame 4, and is configured to reciprocate in a direction B perpendicular to the conveyance direction A of the recording paper P. The recording paper P conveyed in the A direction from a paper supply unit (not shown) is introduced between a platen roller (not shown) and the ink jet head 3 and is ejected from the ink jet head 3 toward the recording paper P. As a result, predetermined recording is performed, and then the paper is discharged by the paper discharge roller 6.

  As shown in FIG. 1B, the inkjet head 3 includes a cavity unit 11 and a piezoelectric actuator 12 in order from the lower side, and a flexible wiring board 13 (signal) that supplies a drive signal to the upper surface of the piezoelectric actuator 12. Line).

  As shown in FIG. 2, the cavity unit 11 includes a laminate 14 composed of a plurality of plate members. A top plate 15 is provided on the upper side of the laminate 14, and a nozzle plate 16 having a nozzle hole 16 a and a spacer plate 17 having a through hole 17 a corresponding to the nozzle hole 16 a are bonded to the lower side. A plate assembly 18 is integrally attached. A piezoelectric actuator 12 for selectively discharging ink (liquid) in each pressure chamber 14Aa is joined to the upper side of the top plate 15. Further, a filter 19 for capturing dust contained in the ink is provided in the opening 11 a of the cavity unit 11. The nozzle plate 16 is a synthetic resin (for example, polyimide resin) plate in which one nozzle hole 16a is provided for each pressure chamber 14Aa of the cavity plate 14A (which constitutes the laminate 14). The nozzle plate 16 may be a metal plate.

  As shown in FIG. 3, the laminated body 14 is formed by metal diffusion bonding by overlapping a cavity plate 14A, a base plate 14B, an aperture plate 14C, two manifold plates 14D and 14E, and a damper plate 14F in order from the upper side. It is. The six plates 14A to 14F are stacked in alignment with each other so that an ink flow path is individually formed for each nozzle hole 16a. Here, the cavity plate 14A is a metal plate in which openings functioning as a plurality of pressure chambers 14Aa are regularly formed corresponding to the nozzle rows. The base plate 14B is a metal plate provided with communication holes 14Ba from the manifolds 14Da and 14Ea (common ink chambers) to the pressure chambers 14Aa and communication holes 14Bb from the pressure chambers 14Aa to the nozzle holes 16a. On the upper surface of the aperture plate 14C, a communication passage 21 that communicates each pressure chamber 14Aa and the manifolds 14Da, 14Ea is formed as a recessed passage, and from the manifolds 14Da, 14Ea (common ink chamber) to each pressure chamber 14Aa. This is a metal plate provided with a communication hole 14Ca and a communication hole 14Cb from each pressure chamber 14Aa to the nozzle hole 16a. The manifold plates 14D and 14E are metal plates provided with communication holes 14Db and 14Eb from the pressure chambers 14Aa to the nozzle holes 16a in addition to the manifolds 14Da and 14Ea. The damper plate 14F is a metal plate provided with a communication hole 14Fb for communicating each pressure chamber 14Aa with each nozzle hole 16a in addition to a damper chamber 14Fa formed as a recess on the lower surface.

  As described above, the cavity unit 11 includes the plurality of nozzle holes 16a, the plurality of pressure chambers 14Aa communicating with each of the plurality of nozzle holes 16a, and the manifolds 14Da and 14Ea for temporarily storing ink supplied to the pressure chambers 14Aa. It is set as the composition including.

  As shown in FIG. 4, the piezoelectric actuator 12 is formed by laminating a plurality of piezoelectric material layers 12a, 12b, and 12c. The piezoelectric material layers 12a to 12c are made of a lead zirconate titanate (PZT) ceramic material (piezoelectric sheet) having ferroelectricity, and are polarized in the thickness direction thereof (see FIGS. 6A and 6B). ).

  The piezoelectric actuator 12 has the first active portions S11 and S12 corresponding to the central portion of the pressure chamber 14Aa when the pressure chamber 14Aa is viewed in plan (when viewed from the stacking direction of the cavity unit 11 and the piezoelectric actuator 12). , S13 (first portion) and second active portions S21, S22 (second portion) corresponding to the left and right portions on the outer peripheral side of the central portion of the pressure chamber 14Aa. Here, the central portion of the pressure chamber 14Aa is a central portion in the nozzle row direction X in which the nozzle holes 16a are arranged.

  2nd active part S21, S22 respond | corresponds not only to the area | region corresponding to girder part 14Ab which is a wall which partitions adjacent pressure chamber 14Aa, but to an inner side part (center part side) rather than outer periphery 14Aaa of pressure chamber 14Aa. It is set as the structure containing an area | region.

  The first active portions S11 to S13 have a portion in which the piezoelectric material layers 12a and 12c are sandwiched between the individual electrode 21 provided for each pressure chamber 14Aa and the first constant potential electrodes 22A and 22B. On the other hand, the second active portions S21 and S22 have portions where the piezoelectric material layers 12a and 12b are sandwiched between the individual electrode 21 and the second constant potential electrode 23. The electrodes 21, 22A, 22B are made of a metal material such as Ag—Pd.

  A driver IC 90 (see FIG. 1B) that supplies a drive signal is electrically connected to each individual electrode 21 through the flexible wiring board 13 (signal line). The driver IC 90 and the flexible wiring board 13 constitute voltage applying means for applying a driving voltage to the first and second active portions S11 to S13, S21, and S22 of the piezoelectric actuator 12.

  That is, in order to change the volume of the pressure chamber 14 </ b> Aa, the individual electrode 21 is selectively applied with a first potential (ground potential) and a different second potential (for example, 20 V) through the flexible wiring board 13. The The first constant potential electrodes 22A and 22B are always applied with the first potential (ground potential), and the second constant potential electrode 23 is always applied with the second potential (for example, 20V).

  As described above, the piezoelectric actuator 12 has the individual electrodes 21 corresponding to the respective pressure chambers 14Aa, and the first potential (ground potential) and the second potential (positive potential) as drive signals to the individual electrodes 21. Is selectively applied to change the volume of the pressure chamber 14Aa and eject ink from the nozzle hole 16a.

  More specifically, the individual electrode 21 is shorter than the pressure chamber 14Aa in the direction Y orthogonal to the nozzle row direction X (see FIG. 6B), longer than the pressure chamber 14Aa in the nozzle row direction X, and has the first activity. It is formed so as to occupy both these regions across the region corresponding to the portions S11 to S13 and the region corresponding to the second active portions S21 and S22. The first constant potential electrodes 22A and 22B are formed so as to be shorter than the pressure chamber 14Aa in the nozzle row direction X and occupy a region corresponding to the first active portions S11 to S13. The first constant potential electrode 22B located on the pressure chamber 14Aa side is formed longer in the nozzle row direction X than the first constant potential electrode 22A located far from the pressure chamber 14Aa. That is, each individual electrode 21 is shared by the first and second constant potential electrodes 22A, 22B, and 23.

  The second constant potential electrode 23 is formed so as to occupy a region corresponding to the second active portions S21 and S22 and a region corresponding to the beam portion 14Ab between the pressure chambers 14Aa adjacent in the direction orthogonal to the nozzle row direction. Has been. That is, the second constant potential electrode 23 extends to a region corresponding to the side in the nozzle row direction of the pressure chamber 14Aa including the region corresponding to the beam portion 14Ab, and is adjacent to the two pressures in the nozzle row direction of the pressure chamber 14Aa. The chambers 14Aa and 14Aa are shared.

  Specifically, in the piezoelectric material layer 12a farthest from the pressure chamber 14Aa, the individual electrode 21 is formed on one surface (the upper surface in FIG. 4), and the second electrode (the lower surface in FIG. 4) is the second. By alternately forming one constant potential electrode 22A and the second constant potential electrode 23, the first active portion S11 and the second active portion S21 are formed side by side in the same piezoelectric material layer 12a. Further, in the piezoelectric material layer 12b, the first constant potential electrode 22A and the second constant potential electrode 23 are alternately formed on one surface (the upper surface in FIG. 4), and the other surface (the lower surface in FIG. 4). By forming the individual electrode 21 on the side), the first active portion S12 and the second active portion S22 corresponding to the first active portion S11 and the second active portion S21 of the piezoelectric material layer 12a. Are formed side by side. Further, in the piezoelectric material layer 12c closest to the pressure chamber 14Aa, the individual electrode 21 is formed on one surface (the upper surface in FIG. 4), and the first surface is formed on the other surface (the lower surface in FIG. 4). The first active portion S13 is formed by forming the constant potential electrode 22B. The first active portion S13 is longer in the nozzle row direction than the first active portions S11 and S12 because the constant potential electrode 22B is longer in the nozzle row direction X than the constant potential electrode 22A. .

  Further, the electrodes 21, 22A, 22B, and 23 of the piezoelectric material layers 12a to 12c are arranged as shown in FIG. That is, on the upper surface side (first layer, third layer) of the piezoelectric material layers 12a and 12c, the individual electrodes 21 are formed at a constant pitch in the nozzle row direction corresponding to each pressure chamber 14Aa. Adjacent individual electrodes 21 are formed with a half-pitch shift in the nozzle row direction, and between these rows, the individual electrodes 21 are connected to the connection terminals (not shown) of the flexible wiring board 13. Terminal portions 21a are formed in a staggered pattern.

  On the lower surface side (second layer) of the piezoelectric material layer 12a, first constant potential electrodes 22A corresponding to the pressure chambers 14Aa are formed at a constant pitch in the nozzle row direction, and one end thereof is connected to the ground potential. And connected to the first common electrode 22Aa extending in the nozzle row direction. Further, second constant potential electrodes 23 are formed between the first constant potential electrodes 22A, respectively, and one end portion thereof is also set to a positive potential (for example, 20V: constant), and extends in the nozzle row direction X. Are connected to the common electrode 23a. Between the adjacent pressure chambers 14Aa, the individual electrode 21 on the upper surface side of the piezoelectric material layer 12a is connected to the individual electrode 21 on the upper surface side of the piezoelectric material layer 12c located below the through hole 24 (inside Intermediate electrodes 25 for electrical connection using a conductive material filling) are formed in a staggered pattern (see FIG. 6B).

  On the lower surface side of the piezoelectric material layer 12c, the first constant potential electrodes 22B corresponding to the pressure chambers 14Aa are formed at a constant pitch in the nozzle row direction X, and one end thereof is set to the ground potential and the nozzle row direction. The first common electrode 22Ba extending to X is connected to the first common electrode 22Ba. The first constant potential electrode 22B located on the pressure chamber 14Aa side is formed to have a longer length in the nozzle row direction X than the first constant potential electrode 22A that is separated from the pressure chamber 14Aa.

  As shown in FIGS. 6A and 6B, in the first active portions S11 to S13, a second potential is applied to the individual electrode 21, and a first potential is applied to the first constant potential electrodes 22A and 22B. Is polarized in the same direction (polarization direction) as the direction of the voltage applied when deformed. On the other hand, the second active portions S21 and S22 have a direction of a voltage applied when the first electrode is applied to the individual electrode 21 and the second electric potential is applied to the second constant potential electrode 23 to be deformed. Polarized in the same direction. That is, the direction in which the voltage is applied and the polarization direction are the same. Here, in FIGS. 6A and 6B, the “valid when ON” portion is a portion to which the voltage (20 V) is applied when the second potential is applied to the individual electrode 21. The “effective when OFF” portion corresponds to the second active portion to which a voltage (20 V) is applied when the first potential is applied to the individual electrode 21.

The first constant potential electrodes 22A and 22B are always set to the first potential (ground potential), and the second constant potential electrode 23 is always set to the second potential (positive potential). The individual electrode 21 is selectively given a first potential (ground potential) and a second potential (positive potential) in order to change the volume of the pressure chamber 14Aa. That is, as shown in the following Table 1, the voltage application direction is the same during polarization and during driving, but the first constant potential electrodes 22A and 22B are always set to the ground potential (0 V), and the second The constant potential electrode 23 is always set to a positive potential (20V: constant), and the individual electrode 21 is applied with a positive potential (20V: constant), or the application is canceled (see FIG. 27A). ). Therefore, when a positive potential is applied to the individual electrode 21, a voltage is applied to the first active portions S11 to S13, but no voltage is applied to the second active portions S21 and S22. When a positive potential is not applied to the electrode 21 and the individual electrode 21 is set to the ground potential, no voltage is applied to the first active portions S11 to S13, and a voltage is applied to the second active portions S21 and S22. It will be. Here, as shown in Table 1, the voltage applied between the electrodes at the time of driving is smaller than the voltage applied at the time of polarization, and suppresses deterioration due to repeated application of voltage between the electrodes. Yes.

By arranging the electrodes 21, 22 </ b> A, 22 </ b> B, and 23 in this way, the voltage applied to the first active portions S <b> 11 to S <b> 13 that applies the second potential (ground potential) to the individual electrode 21 by the voltage applying unit. When the voltage is not applied (standby time), the first active portions S11 to S13 are not expanded or contracted in the first and second directions Z and X and are not deformed. At this time, the second active portions S21 and S22 are in a voltage application state, extend in the stacking direction Z (first direction) toward the pressure chamber 14Aa, and extend in the nozzle row direction X (second) orthogonal to the stacking direction Z. The second active portions S21 and S22 located on the side in the nozzle row direction are warped in the direction away from the pressure chamber 14Aa by the action of the top plate 15 as a restraining plate. Deform. The deformation of the second active portions S21 and S22 contributes to increasing the volume change of the pressure chamber 14Aa as shown in FIG. 7A, and a large amount of ink is sucked into the pressure chamber 14Aa from the manifolds 14Da and 14Ea. Contribute to

  On the other hand, when a voltage is applied to the first active portions S11 to S13, which applies a first potential (positive potential: 20V) to the individual electrode 21 (during driving), the first active portions S11 to S13 are applied. Is applied with a voltage in the same direction as the polarization direction, expands in the stacking direction Z toward the pressure chamber 14Aa by the piezoelectric lateral effect, and contracts in the nozzle row direction X perpendicular to the stacking direction Z, thereby causing a pressure in the pressure chamber 14Aa. It will be in the state of projecting and deforming in the direction of. On the other hand, since the top plate 15 is not affected by the electric field and does not spontaneously shrink, the top plate 15 is perpendicular to the polarization direction between the upper piezoelectric material layer 12 c and the lower top plate 15. A difference is produced in the distortion. With this fact and the fact that the top plate 15 is fixed to the cavity plate 14A, the piezoelectric material layer 12c and the top plate 15 try to deform so as to protrude toward the pressure chamber 14Aa (unimorph deformation). ). For this reason, the volume of the pressure chamber 14Aa decreases, the ink pressure increases, and ink is ejected from the nozzle holes 16a.

  When the voltage is applied to the first active portions S11 to S13, the second active portions S21 and S22 are not applied with a voltage, so that they do not expand and contract in the first and second directions Z and X. It will return to the state that does not. Therefore, when the first active portions S11 to S13 project and deform in the direction of the pressure chamber 14Aa, the second active portions S21 and S22 return to the undeformed state, as shown in FIG. 7B. In addition, the influence of the deformation of the first active portions S11 to S13 is canceled by the second active portions S21 and S22, hardly reaching the adjacent pressure chamber 14Aa, and crosstalk is suppressed. That is, the second active portion S11 to S13 by switching between application and non-application of a voltage to the first active portion S11 to S13 is prevented from propagating to the adjacent pressure chamber 14Aa. Application and non-application of voltage to the active portions S21 and S22 are switched.

  Thereafter, when the individual electrode 21 is returned to the same potential (ground potential) as the first constant potential electrodes 22A and 22B, as described above, the first active portions S11 to S13 are not deformed, and the second active portion The portions S21 and S22 are deformed so as to warp away from the pressure chamber 14Aa, and the volume of the pressure chamber 14Aa returns to the original volume, so that ink is sucked into the pressure chamber 14Aa from the manifolds 14Da and 14Ea.

  Due to the deformation of the first active portions S11 to S13 and the second active portions S21 and S22, the ink discharge operation is repeated. In each discharge operation, the volume change of the pressure chamber 14Aa is increased to increase the discharge efficiency. In addition, the crosstalk is suppressed.

  For Example 1 and the conventional example (see FIG. 40), the ratio of the change in the cross-sectional area of the adjacent pressure chamber was determined. As shown in Table 2, it was 24% in the case of the conventional example. On the other hand, in the case of Example 1, it is 11%, and in the case of Example 1, the change rate is almost halved as compared with the conventional example, and it can be seen that the effect of suppressing crosstalk is exhibited.

In the first embodiment, the second active portions S21 and S22 are located between the region corresponding to the outer peripheral side of the central portion of the pressure chamber 14Aa in the nozzle row direction X and the region corresponding to the beam portion 14Ab. Although arranged across, it is also possible to configure as shown in FIG. That is, the second constant potential electrode 23A is provided only in the region corresponding to the digit portion 14Ab regardless of the region corresponding to the pressure chamber 14Aa, and the second active portions S21a and S22a are regions corresponding to the digit portion 14Ab. It can be configured to exist only in In this case, even if a voltage is applied to the second active portions S21a and S22a and the second active portions S21a and S22a are deformed, it does not contribute to the expansion of the volume of the pressure chamber 14Aa, but crosstalk is not caused. The inhibitory effect is exhibited.

  Conversely, as shown in FIG. 9, the second active portions S <b> 21 b and S <b> 22 b can be configured to exist only in a region corresponding to the outer peripheral portion of the pressure chamber 14 </ b> Aa. That is, the second constant potential electrode 23B can be provided only in a region corresponding to a portion on the outer peripheral side of the central portion of the pressure chamber 14Aa regardless of a region corresponding to the beam portion 14Ab. In this case, the second active portions S21 and S22 described above are arranged between the region corresponding to the outer peripheral portion of the pressure chamber 14Aa and the region corresponding to the beam portion 14Ab. The nozzle row direction lengths of the second active portions S21b and S22b are shorter than those (see FIG. 4). Therefore, although the degree of the effect of suppressing the crosstalk and the effect of contributing to the volume change is inferior, the point of exhibiting these effects is the same as described above.

  Further, as shown in FIG. 10, a piezoelectric material layer 12d is provided on the upper side of the cavity plate 14A via an insulating layer 12e having a thin layer thickness without providing a top plate. It is also possible to form the second active portion. In this case, similarly to the piezoelectric material layer 12b, the first and second constant potential electrodes 22A and 23 are alternately formed on one surface (upper surface) of the piezoelectric material layer 12d, and the other surface ( Individual electrodes 21 are formed on the lower surface. As a result, the first active portions S11, S12, S13a, S14 corresponding to the central portion of each pressure chamber 14Aa and the second active portions S21, S22, S23, S24 corresponding to the outer peripheral portion thereof, respectively. It is formed.

  FIG. 11 shows the relationship between the polarization direction, the effective portion when ON (first active portion) when a voltage is applied, and the effective portion when OFF (second active portion) when no voltage is applied. (A) Shown in (b).

  In this way, the first active part S11, S12, S13a, S14 and the second active part S21, S22, S23, S24 are not unimorph deformed but deformed by the longitudinal effect, The active portions S21 to S24 cannot be deformed to warp away from the pressure chamber 14Aa (that is, deformation in the direction in which the pressure chamber 14Aa is expanded) like unimorph deformation. Therefore, the effect of suppressing the crosstalk can be obtained, but the effect of increasing the volume change of the pressure chamber 14Aa cannot be obtained.

  Similarly, in the structure (see FIG. 8) in which the second constant potential electrode 23A is provided only in the region corresponding to the beam portion 14Ab, a piezoelectric layer is formed on the pressure chamber 14Aa side through the insulating layer 12e having a thin layer thickness. Needless to say, the material layer 12d may be provided. In this case, as shown in FIG. 12, the piezoelectric material layer 12d has the first and second constant potential electrodes 22A and 23A alternately arranged on one surface (upper surface) as in the piezoelectric material layer 12b. The individual electrode 21 is disposed on the other surface (lower surface). As a result, the first active portions S11, S12, S13a, S14 corresponding to the central portion of each pressure chamber 14Aa and the second active portions S21, S22, S23, S24 corresponding to the outer peripheral portion thereof, respectively. It is formed.

  FIG. 13 shows the relationship between the polarization direction, the effective portion at the time of ON when the voltage is applied (first active portion), and the effective portion at the time of OFF when the voltage is not applied (second active portion). (A) Shown in (b).

When the first and second constant potential electrodes 22A and 23 are alternately formed in the nozzle row direction X on the same surface as in the first embodiment, the distance between the electrodes cannot be increased. Therefore, the length of these electrodes in the nozzle row direction cannot be increased. However, as shown in Example 2 below, it is possible to increase the length of the insulating layer by using a thin insulating layer.
(Example 2)
In this example, as shown in FIG. 14, the piezoelectric actuator has a laminated structure in which an insulating layer 12f having a smaller thickness than the piezoelectric material layers 12a and 12b is sandwiched between the piezoelectric material layer 12a and the piezoelectric material layer 12b. It is said. The insulating layer 12f can be formed from the same material as the piezoelectric material layers 12a to 12d.

Only the first constant potential electrode 22B is formed on one surface (upper surface) side of the insulating layer 12f, and only the second constant potential electrode 23 is formed on the other surface (lower surface) side with a constant interval. Yes. As a result, the first constant potential electrode 22B and the second constant potential electrode 23 are electrically isolated via the insulating layer 12f. However, as in the first embodiment, the piezoelectric material layer 12a and the piezoelectric material layer 12a are electrically isolated from each other. It is formed between the material layer 12b. Thereby, the first active portions S11a, S12a, S13 corresponding to the central portion of each pressure chamber 14Aa and the second active portions S21c, S22 corresponding to the outer peripheral portion thereof are formed, respectively.

  As described above, the first constant potential electrode 22B and the second constant potential electrode 23 are separated from each other with the insulating layer 12f interposed therebetween, so that the piezoelectric material layer 12a and the piezoelectric material layer 12b are interposed. The length of the formed first constant potential electrode 22B in the nozzle row direction can be increased, and an advantageous electrode arrangement can be realized in increasing the volume change of the pressure chamber 14Aa. Also in the case of Example 2, as shown in Table 2, the rate of change in the cross-sectional area of the adjacent pressure chamber is 11%, and the rate of change is almost halved compared to the conventional example as in Example 1, It can be seen that the effect of suppressing crosstalk is exhibited.

By using an insulating layer having such a thin layer thickness, a structure as shown in Example 3 below can be formed.
(Example 3)
In this example, as shown in FIG. 15, the uppermost piezoelectric material layer 12a in the second embodiment is omitted, and instead, a layer similar to the insulating layer 12f is provided between the piezoelectric material layer 12c and the top plate 15. Another insulating layer 12g having a small thickness is disposed, and the second constant potential electrode 23 is formed on the upper surface side of the insulating layer 12g, and the first constant potential electrode 22B is formed on the lower surface side. In this case, the first and second constant potential electrodes 22B and 23 are formed symmetrically with the individual electrode 21 disposed on the lower surface side of the piezoelectric material layer 12b interposed therebetween. Thereby, the first active portions S12a and S13a corresponding to the central portion of each pressure chamber 14Aa and the second active portions S22 and S23 corresponding to the outer peripheral portion thereof are formed.

Further, the piezoelectric material layer as described above may be at least one layer, and may be configured as shown in the following Example 4.
Example 4
In this example, as shown in FIG. 16, the individual electrode 21 is formed on one surface (upper surface) side of the piezoelectric material layer 12a, and the first and second constant potential electrodes 22B, 23 are alternately formed in the nozzle row direction. Thus, the first active portion S11a corresponding to the central portion of each pressure chamber 14Aa and the second active portions S21, S21 corresponding to both sides of the outer peripheral portion thereof are formed.

  In this way, the top fret 15 functions as a restraint plate, and although the number of piezoelectric material layers is smaller than that of the first to third embodiments and the amount of deformation is small, the piezoelectric material layer 12a is one layer. Excellent discharge efficiency due to unimorph deformation can be realized.

Even when such a piezoelectric material layer is a single layer, as shown in Example 5 below, a structure using an insulating layer with a thin layer thickness can be used.
(Example 5)
In this example, as shown in FIG. 17, an insulating layer 12 h is sandwiched between the piezoelectric material layer 12 a and the top plate 15. An individual electrode 21 is formed on the upper surface side of the piezoelectric material layer 12a, and a second constant potential electrode 23 is formed on the lower surface side. The first constant potential electrode 22B is formed on the lower surface side of the insulating layer 12h. Thereby, the first active portion S11b corresponding to the central portion of each pressure chamber 14Aa and the second active portion S21 corresponding to the outer peripheral portion thereof are formed.

  Also in this case, it can be seen that the effect of suppressing crosstalk is exhibited by applying and not applying voltage, as shown in FIGS. 18 (a) and 18 (b). In the case of this Example 5, as shown in Table 2, the rate of change in the cross-sectional area of the adjacent pressure chamber is 2%, the rate of change is greatly reduced compared to the conventional example, and the effect of suppressing crosstalk is It can be seen that it is particularly large.

It is not necessary to provide the second active part on both sides of the first active part as in the above-described embodiment, and it is only necessary to exert a crosstalk suppressing effect only on one side of the first active part. As shown in the sixth embodiment, it is possible to provide the second active part only on one side of the first active part.
(Example 6)
In this example, as shown in FIG. 19, the individual electrodes 21A are arranged in a part of the region corresponding to the pressure chamber 14Aa and the region corresponding to the beam portion 14Ab.

  The individual electrode 21A is provided on one surface (upper surface) side of the piezoelectric material layer 12a, and the first and second constant potential electrodes 22A are provided on the other surface (lower surface) side corresponding to the respective side portions of the individual electrode 21A. , 23A are formed. The individual electrode 21A is formed on the upper surface side of the piezoelectric material layer 12c, and the first constant potential electrode 22A is formed on the lower surface side. Thereby, the first active portions S11, S12, S13a corresponding to the central portion of each pressure chamber 14Aa and the second active portions S21c, S22c corresponding to the outer peripheral portion thereof are formed, respectively.

  In this way, the crosstalk suppressing effect is exhibited only on the side where the second active portions S21c and S22c are arranged.

Further, as in Example 7 below, the first constant potential electrode is formed so as to extend along the nozzle row direction, and is common to each pressure chamber formed in a row in the nozzle row direction. Is also possible.
(Example 7)
In this example, as shown in FIG. 20, there are four piezoelectric material layers 12a to 12d, and the individual electrode 21 is provided on one surface (upper surface) side of the piezoelectric material layer 12a farthest from the pressure chamber 14Aa. Second constant potential electrodes 23 are respectively formed on the surface (lower surface) side. Then, the first constant potential electrode 22C is formed on one surface side of the third piezoelectric material layer 12c and the individual electrode 21B is formed on the other surface side near the pressure chamber 14Aa from the piezoelectric material layer 12a. A first constant potential electrode 22C is formed on the pressure chamber 14Aa side of the fourth piezoelectric material layer 12d closer to the pressure chamber 14Aa from the piezoelectric material layer 12a. Thus, the first active portions S11 ′, S13, S14 corresponding to the central portion of each pressure chamber 14Aa and the second active portion S21 ′ corresponding to the outer peripheral portion thereof are formed.

  Then, the electrodes 21, 21B, 22C, and 23 of the piezoelectric material layers 12a to 12d are arranged as shown in FIG. 21 when viewed in a plan view. That is, on the upper surface side (first layer) of the piezoelectric material layer 12a and the lower surface side (third layer) of the piezoelectric material layer 12c, the individual electrodes 21 and 21B correspond to the pressure chambers 14Aa in the nozzle row direction at a constant pitch. X is formed. The adjacent individual electrodes 21 and 21B are formed so as to be shifted by a half pitch in the nozzle row direction, and the connection terminal portions 21a and 21Ba of the individual electrodes 21 and 21B are formed in a staggered manner between them. And the connection terminal (not shown) of the flexible wiring board 13 is connected to the connection terminal part 21a of the individual electrode 21, and the connection terminal part 21a of each individual electrode 21 is a through hole penetrating the piezoelectric material layers 12a to 12c. 24 (filled with a conductive material inside), and electrically connected to the connection terminal portion 21Ba of each individual electrode 21B via an intermediate electrode 25 formed on the lower surface side of the piezoelectric material layer 12a and the upper surface side of the piezoelectric material layer 12c. (See FIG. 22B). The individual electrodes 21 on the upper surface side of the piezoelectric material layer 12a are formed longer in the nozzle row direction than the individual electrodes 21B on the lower surface side of the piezoelectric material layer 12c.

Also, on the lower surface side of the piezoelectric material layer 12a, second constant potential electrodes 23 corresponding to the pressure chambers 14Aa are formed at a constant pitch in the nozzle row direction, and one end portions thereof extend in the nozzle row direction. Connected to the common electrode 23a. A first constant potential electrode 22C is formed on the upper surface side of the piezoelectric material layer 12c and the lower surface side of the piezoelectric material layer 12d so as to extend in the nozzle row direction corresponding to the pressure chambers 14Aa.

  Thus, since the first constant potential electrode 22C is formed in the nozzle row direction X and is shared by the pressure chambers 14Aa in the nozzle row direction, the arrangement of the electrodes 21, 21B, 22C, and 23 is simple. Therefore, it is advantageous for downsizing. FIG. 22 shows the relationship between the polarization direction, the effective portion at the time of ON when the voltage is applied (first active portion), and the effective portion at the time of OFF when the voltage is not applied (second active portion). (A) Shown in (b).

In Examples 1, 2, and 4 to 7 described above, the connection portion with the flexible wiring board 13 is arranged on the piezoelectric material layer 12a farthest from the pressure chamber. Since there is a risk of variation in deformation characteristics due to the flow of the solder, an individual electrode is arranged between the piezoelectric material layer 12a and the piezoelectric material layer 12b located inside the piezoelectric material layer 12b as in Example 8 below. Thus, similar to the case of the third embodiment, such a problem can be avoided.
(Example 8)
In this example, among the plurality of piezoelectric material layers constituting the piezoelectric actuator, a surface individual electrode for connection is provided on one surface (the most separated surface) side of the piezoelectric material layer (the most separated layer) farthest from the pressure chamber. Individual electrodes are formed on the other surface side.

  As shown in FIG. 23, the individual electrode 21 and the surface individual electrode 21b are electrically connected by a through hole 24 (filled with a conductive material) penetrating the piezoelectric material layer 12a. The first constant potential electrode 22D is formed on the surface of the piezoelectric material layer 12c closest to the pressure chamber 14Aa on the pressure chamber 14Aa side. On the other hand, the second constant potential electrode 23A is the farthest surface 12aa which is the surface of the plurality of piezoelectric material layers 12a to 12c opposite to the pressure chamber 14Aa of the piezoelectric material layer 12a located farthest from the pressure chamber 14Aa. Formed on top.

  The individual electrode 21 is formed on the surface of the piezoelectric material layer 12a on the pressure chamber 14Aa side. That is, the piezoelectric material layer 12a is formed on the pressure chamber 14Aa side surface of the piezoelectric material layer 12a (the farthest separated layer) which is one of the surfaces of the piezoelectric material layers 12a to 12c and is different from the farthest separated surface 12aa. And the surface individual electrode 21b used as the input terminal to the individual electrode 21 is formed in the area | region (area | region corresponding to beam part 14Ab) outside the outer periphery of pressure chamber 14Aa of the most spaced surface 12aa. The individual surface electrode 21b and the individual electrode 21 are electrically connected through a through hole (conductive material 24) penetrating the piezoelectric material layer 12a. The surface individual electrode 21b is formed in a region between the adjacent pressure chambers 14Aa (a region corresponding to the so-called beam portion 14Ab).

  Thus, the first active portions S11 and S12 are formed corresponding to the central portion of the pressure chamber 14Aa, and the second active portion S22 'is formed on the outer peripheral portion thereof. Therefore, the second active portion S22 ′ is formed in the piezoelectric material layers 12b and 12c on the pressure chamber 14Aa side, which is a layer other than the most separated layer (piezoelectric material layer 12a) among the plurality of piezoelectric material layers 12a to 12c. Will be.

Further, the electrodes 21, 22D, and 23A formed on the surfaces of the piezoelectric material layers 12a to 12c are arranged as shown in FIG. That is, on the upper surface side of the piezoelectric material layers 12a and 12c (the first layer and the third layer), the second constant potential electrodes 23A corresponding to the pressure chambers 14Aa are formed in the nozzle row direction at a constant pitch and adjacent to each other. The matching second constant potential electrode 23A is formed with a half pitch shift in the nozzle row direction. And between the nozzle row direction of the 2nd constant potential electrode 23A of the upper surface side of the piezoelectric material layer 12a, the surface individual electrode 21b is formed corresponding to each individual electrode 21, and the surface individual electrode 21b of the surface individual electrode 21b The opposite end of the second constant potential electrode 23 </ b> A extends to a portion between the adjacent pressure chambers 14 </ b> Aa, and is formed in a staggered manner as a connection terminal portion 21 </ b> Ba connected to the connection terminal of the flexible wiring board 13. .

  On the lower surface side of the piezoelectric material layer 12a, individual electrodes 21 corresponding to the pressure chambers 14Aa are formed at a constant pitch in the nozzle row direction, and the connection terminal portions 21a pass through the piezoelectric material layer 12a. 24 (the inside is filled with a conductive material) is connected to the connection terminal portion 21Ba of the surface individual electrode 21b (see FIG. 25A).

  On the lower surface side of the piezoelectric material layer 12c, a first constant potential electrode 22D that is common to two adjacent rows of piezoelectric chambers 14Aa is formed so as to extend in the nozzle row direction.

  In this way, since the connection terminal portion 21Ba to which the connection terminal of the flexible wiring board 13 is connected is formed on the region corresponding to the girder portion 14Ab that is not deformed during driving, the connection with the connection terminal of the flexible wiring board 13 is performed. Even when solder flows in, sometimes the variation in deformation characteristics of each first active portion is less likely to occur.

  FIG. 25 shows the relationship between the polarization direction, the effective portion at the time of ON when the voltage is applied (first active portion), and the effective portion at the time of OFF when the voltage is not applied (second active portion). (A) Shown in (b). Then, it can be seen that the effect of suppressing the crosstalk is exhibited by the application / non-application of the voltage, as shown in FIGS. In the case of this Example 8, as shown in Table 2, the rate of change in the cross-sectional area of the adjacent pressure chamber is 12%, and the rate of change is almost halved compared to the conventional example as in Example 1, It can be seen that the effect of suppressing crosstalk is exhibited.

  In Embodiments 1 to 7 described above, as shown in FIG. 27A, discharge is performed when a voltage is applied to the first active portion (that is, when a second potential is applied to the individual electrode). However, in the case of the eighth embodiment and the tenth embodiment described later, as shown in FIG. 27B, conversely, when the application of the voltage to the first active portion is released (that is, to the individual electrode). (When the first potential is applied).

Further, even in the case where the surface individual electrode is used as in the case of the eighth embodiment, the voltage to the first active portion can be reduced in the same manner as in the first to seventh embodiments. It is also possible to discharge at the time of application (see FIG. 27A).
Example 9
In this example, as shown in FIG. 28, the piezoelectric actuator has a two-layer structure, and the second constant potential electrode 23C is formed on the upper surface side of the upper piezoelectric material layer 12a, and the individual electrode 21 is formed on the lower surface side. . The first constant potential electrode 22C is formed on the lower surface side of the lower piezoelectric material layer 12b. As a result, the first active portion S12 corresponding to the central portion of each pressure chamber 14Aa and the second active portion S21 corresponding to the outer peripheral portion thereof are formed.

  By doing so, as shown in FIG. 29, the individual surface electrode 21c that becomes a joint with the flexible wiring board 13 (COP) is formed in a region corresponding to the beam portion 14Ab between the pressure chambers 14Aa. In addition, since the time during which a voltage is applied between the second constant potential electrode 23C and the individual electrode 21 is short, unlike the case of the eighth embodiment, a short circuit due to migration is avoided.

Also, the electrodes on the upper and lower surfaces of the piezoelectric material layers 12a and 12b are arranged as shown in FIG. That is, on the upper surface side of the piezoelectric material layer 12a, the second constant potential electrodes 23C corresponding to the pressure chambers 14Aa are formed at a constant pitch in the nozzle row direction, and both side portions in the direction perpendicular to the nozzle row direction. Are connected by common electrodes 23Ca and 23Cb. The adjacent second constant potential electrodes 23C and 23C are formed with a half-pitch shift in the nozzle row direction, and are between the adjacent common electrodes 23Ca and 23Cb and the second constant potential electrode 2 is formed.
On the side opposite to the side on which 3C is formed, the surface individual electrode 21c connected to the connection terminal of the flexible wiring board 13 is formed.

  On the lower surface side of the piezoelectric material layer 12a, individual electrodes 21 are formed at a constant pitch in the nozzle row direction corresponding to each pressure chamber 14Aa, and a part of them is formed on the surface individual electrode 21c on the upper surface of the piezoelectric material layer 12a. The through hole 24 (filled with a conductive material inside) is used to project so as to be a connection terminal portion 21a for electrical connection.

  On the lower surface side of the piezoelectric material layer 12b, first constant potential electrodes 22C corresponding to the pressure chambers 14Aa are formed at a constant pitch in the nozzle row direction, and their end portions are adjacent to the first constant potential. The electrodes 22C and the connection part 22Ca are connected to each other.

  FIG. 30 shows the relationship between the polarization direction, the effective portion at the time of ON when the voltage is applied (first active portion), and the effective portion at the time of OFF when the voltage is not applied (second active portion). (A) Shown in (b). Then, it can be seen that the effect of suppressing crosstalk is exhibited by applying and not applying voltage, as shown in FIGS.

Further, by configuring as in the following Example 10, as in Example 9, a short circuit due to migration is prevented, and as in Example 8, using the surface individual electrode, the first active part is formed. The discharge can be performed when the application of the voltage is canceled (see FIG. 27B).
(Example 10)
In this example, as shown in FIG. 32, the first constant potential electrode 22D is formed on the upper surface side of the piezoelectric material layer 12a, the individual electrode 21 is formed on the lower surface side, and the first constant potential electrode 22D is formed on the upper surface side of the piezoelectric material layer 12c. Two constant potential electrodes 23D and a first constant potential electrode 22E are formed on the lower surface side. The individual electrodes 21 are respectively connected to the surface individual electrodes 21c by using through holes 24 (filled with a conductive material inside) that penetrate the piezoelectric material layer 12a (see FIG. 33B). Thus, the second active portion S22 is formed corresponding to the central portion of the pressure chamber 14Aa, and the first active portions S11 and S12 ′ are formed on the outer peripheral portion thereof.

  In this case, the relationship between the polarization direction, the effective portion at the time of ON when the voltage is applied (first active portion), and the effective portion at the time of OFF when the voltage is not applied (second active portion) is shown in FIG. 33 (a) and (b). Then, it can be seen that the effect of suppressing the crosstalk is exhibited by the application / non-application of the voltage, as shown in FIGS.

  In this case as well, as in the case of the ninth embodiment, it is possible to avoid variations in deformation characteristics due to the flow of solder at the time of connection, and between the first constant potential electrodes 22D and 22E and the individual electrodes 21. The time during which the potential difference occurs is short, and a short circuit due to migration is avoided.

Further, by configuring as in the following Example 11, the number of stacked layers can be reduced without using the surface individual electrodes or through holes, and the first active portion can be formed as in Examples 8 and 10. It is also possible to discharge when the application of voltage is released (see FIG. 27B). (Example 11)
In this example, as shown in FIG. 35, the individual electrode 21 is formed on the upper surface side of the piezoelectric material layer 12a, the second constant potential electrode 23E is formed on the lower surface side, and the first electrode is formed on the lower surface side of the piezoelectric material layer 12b. A constant potential electrode 22F is formed. Thereby, the first active portion S21 is formed corresponding to the central portion of the pressure chamber 14Aa, and the second active portion S11 ′ is formed on the outer peripheral side portion thereof. Note that the ground potential is applied to the individual electrode 21 during standby, as in the eighth and tenth embodiments.

Further, the electrodes on the upper and lower surfaces of each piezoelectric material layer 12a, 12b are shown in FIG.
Are arranged as shown in FIG. That is, on the upper surface side of the piezoelectric material layer 12a, individual electrodes 21 are formed at a constant pitch in the nozzle row direction corresponding to each pressure chamber 14Aa, and a part of the individual electrodes protrudes between them, and the protruding portion Is formed in a staggered pattern so as to be the connection terminal portion 21 a connected to the connection terminal of the flexible wiring board 13.

  On the lower surface side of the piezoelectric material layer 12a, second constant voltage electrodes 23E are formed at a constant pitch in the nozzle row direction corresponding to the pressure chambers 14Aa, and one end portion of the second constant voltage electrodes 23E is located between them. 23Ea is electrically connected. A first constant potential electrode 22E extending in the nozzle row direction is formed on the lower surface side of the piezoelectric material layer 12b so as to be a common electrode for the pressure chambers 14Aa in the nozzle row direction.

  The relationship between the polarization direction, the effective portion when ON (first active portion) when a voltage is applied, and the effective portion when OFF (second active portion) when no voltage is applied is shown in FIG. (A) As shown in (b). Then, it can be seen that the effect of suppressing crosstalk is exhibited by applying and not applying voltage, as shown in FIGS. 38 (a) and 38 (b). In the case of Example 11, as shown in Table 2, the rate of change in the cross-sectional area of the adjacent pressure chamber is 3%, which is greatly reduced compared to the conventional example, and is excellent in the effect of suppressing crosstalk. You can see that

  In this way, since there is no bonding by through holes and the number of stacked layers is small, it can be manufactured at low cost. Moreover, although the cross-sectional area change becomes large, the crosstalk suppression effect is excellent.

Further, by configuring as in the following Examples 12 and 13, in addition to preventing in-row crosstalk between adjacent pressure chambers in the pressure chamber row direction, the compression chamber row belongs to the adjacent compression chamber row. Inter-column crosstalk between adjacent pressure chambers in a direction orthogonal to the direction can also be suppressed.
(Example 12)
In this example, as shown in FIG. 39, the piezoelectric actuator 12 corresponds to the central portion of the pressure chamber 14Aa when viewed in plan (that is, when viewed from the stacking direction of the cavity unit 11 and the piezoelectric actuator 12). A second active portion S32 (second portion) provided corresponding to both sides of the first active portion S31 (first portion) and the central portion of the pressure chamber 14Aa in the predetermined direction, that is, the pressure chamber row direction X. And a third active portion S33 (third portion) provided corresponding to one side portion in a direction Y (crossing direction) orthogonal to (crossing) the pressure chamber row direction X with respect to the central portion of the pressure chamber 14Aa. Part). Here, the central portion of the pressure chamber 14Aa is a central portion in the pressure chamber row direction X in which the pressure chambers 14Aa are arranged (also in the nozzle row direction in which the nozzle holes 16a are arranged).

  The second active portion S32 includes not only a region corresponding to the spar 14Ab that is a wall that partitions adjacent pressure chambers 14Aa, but also a region corresponding to an inner portion (center portion side) of the outer peripheral edge 14Aaa of the pressure chamber 14Aa. Contains. The third active portion S33 includes a region corresponding to the beam portion 14Ac, which is a region outside the outer peripheral edge of the pressure chamber 14Aa, that is, a wall that belongs to the adjacent pressure chamber row and separates the adjacent pressure chambers 14Aa. It is out.

  The first active part S31 includes a piezoelectric material (piezoelectric material layer 12a) sandwiched between the individual electrode 21 and the second constant potential electrode 23F provided for each pressure chamber 14Aa. The second active portion S32 and the third active portion S33 include a piezoelectric material (piezoelectric material layers 12a and 12b) sandwiched between the individual electrode 21 and the first constant potential electrode 23G.

  The piezoelectric actuator 12 changes the volume of the pressure chamber 14Aa by selectively applying a positive potential (first potential) and a ground potential (second potential) as drive signals to the individual electrodes 21. Ink is ejected from the nozzle hole 16a.

  More specifically, as shown in FIGS. 39 and 40, the individual electrode 21 is longer than the pressure chamber 14Aa in the pressure chamber row direction X and shorter than the pressure chamber 14Aa in the direction Y orthogonal to the pressure chamber row direction X. The region corresponding to the first active portion S31, the region corresponding to the second active portion S32, and the region corresponding to the third active portion S33 are formed so as to occupy these regions. The second constant potential electrode 23F is formed to be shorter than the pressure chamber 14Aa in the pressure chamber row direction X and occupy a region corresponding to the first active portion S31. The first constant potential electrode 22G located on the pressure chamber 14Aa side is formed longer in the pressure chamber row direction X than the second constant potential electrode 23F located far from the pressure chamber 14Aa. That is, each individual electrode 21 is shared for the first and second constant potential electrodes 22G and 23F.

  The individual electrode 21 has a portion that is longer than the second constant potential electrode 23F on one side of the orthogonal direction Y. The first constant potential electrode 22G has the individual electrode 21 that is a second constant potential electrode. The part formed longer than 23F has a part formed in a length equal to or longer than that of the individual electrode 21 in the orthogonal direction Y.

  The first constant potential electrode 22G extends to a region corresponding to the second active portion S32 and is formed so as to occupy a region corresponding to the beam portion 14Ab between adjacent pressure chambers 14Aa in the pressure chamber row direction X. . That is, the first constant potential electrode 22G extends to a region corresponding to the side portion in the pressure chamber row direction X including a region corresponding to the beam portion 14Ab, and is adjacent to the two pressure chambers 14Aa, Shared about 14Aa. The first constant potential electrode 22G extends to a region corresponding to the third active portion S33, and also has a region corresponding to the beam portion 14Ac between the pressure chambers 14Aa adjacent in the direction Y orthogonal to the pressure chamber row direction X. It is formed to occupy. That is, the first constant potential electrode 22G extends to the region corresponding to the side portion in the orthogonal direction Y including the region corresponding to the beam portion 14Ac, and is adjacent to the two pressure chambers 14Aa and 14Aa adjacent in the orthogonal direction Y. Are also shared.

  Specifically, the individual electrode 21 is formed on the upper surface side of the upper piezoelectric material layer 12a away from the pressure chamber 14Aa, and the second constant potential electrode 23F is formed on the lower surface side, whereby the first active portion S31. Is formed. In addition, the second and third active portions S32 and S33 are formed by forming the first constant potential electrode 22G on the lower surface side of the piezoelectric material layer 12b on the pressure chamber 14Aa side.

  In addition, the electrodes 21, 23F, 22G of the piezoelectric material layers 12a, 12b are arranged in each layer as shown in FIG. That is, on the upper surface side (first layer) of the piezoelectric material layer 12a, the individual electrodes 21 are formed at a constant pitch in the pressure chamber row direction X corresponding to each pressure chamber 14Aa. The individual electrodes 21 adjacent in the direction Y orthogonal to the pressure chamber row direction X are formed with a half-pitch shift in the pressure chamber row direction X, and the flexible wiring board 13 of each individual electrode 21 is between these rows. The connection terminal portions 21a connected to the connection terminals (not shown) are formed in a staggered pattern.

  On the lower surface side (second layer) of the piezoelectric material layer 12a, second constant potential electrodes 23F corresponding to each pressure chamber 14Aa are formed at a constant pitch in the pressure chamber row direction X, and adjacent second constant potentials. The electrodes 23F are formed with a half-pitch shift in the pressure chamber row direction X, and one end portions thereof are connected to a connection electrode 23Fa extending in the pressure chamber row direction X. The first constant potential electrode 22G is formed so that the connection terminal portion 21a is shared by the two rows of individual electrodes 21 and 21 positioned on the opposite side.

  As shown in FIGS. 41 to 43, the first active portion S31 is applied when the individual electrode 21 is deformed by being applied with the ground potential and the second constant potential electrode 23F is applied with the positive potential. It is polarized in the same direction (polarization direction) as the voltage direction. On the other hand, the second and third active portions S32 and S33 have a direction of a voltage applied when a positive potential is applied to the individual electrode 21 and a ground potential is applied to the first constant potential electrode 22G, and the direction is applied. Polarized in the same direction. That is, during the ink ejection operation, the direction in which the voltage is applied and the polarization direction are the same.

  The second constant potential electrode 23F is always a positive potential, and the first constant potential electrode 22G is always a ground potential. A positive potential and a ground potential are selectively applied to the individual electrode 21 in order to change the volume of the pressure chamber 14Aa. That is, the voltage application direction is the same during polarization and during driving, but the second constant potential electrode 23F is always a positive potential, and the first constant potential electrode 22G is always a ground potential. The positive potential is applied to the electrode 21, or the application is released to a ground potential. Therefore, when the individual electrode 21 is set to the ground potential, a voltage is applied to the first active part S31, but no voltage is applied to the second and third active parts S32 and S33, whereas the individual electrode 21 When a positive potential is applied to 21, no voltage is applied to the first active part S 31, and a voltage is applied to the second and third active parts S 32 and S 33. Here, the voltage applied between the electrodes at the time of driving is smaller than the voltage applied at the time of polarization, so that deterioration due to repeated application of voltage between the electrodes is suppressed.

  In the case where ink is ejected by arranging the electrodes 21, 23F, and 22G in this manner, first, a ground potential is applied to the individual electrode 21 by the voltage applying means. As a result, a voltage is applied to the first active portion S31 in the same direction as the polarization direction, and the first active portion S31 expands in the stacking direction Z (first direction) toward the pressure chamber 14Aa by the piezoelectric lateral effect. It contracts in the orthogonal directions X and Y (second direction) and enters a standby state in which it projects and deforms in the direction within the pressure chamber 14Aa.

  Subsequently, when a positive potential (for example, 20 V) is applied to the individual electrode 21, the first active portion S31 is not expanded or contracted in the stacking direction Z and the direction X orthogonal thereto. At this time, the second and third active portions S32 and S33 are in a voltage application state, extend in the stacking direction Z (first direction) toward the pressure chamber 14Aa, and extend in the two directions X and X orthogonal to the stacking direction Z. Since the top plate 15 serving as a restraining plate tends to shrink in the Y (second direction), the second active portions S32 and S32 located on both sides of the pressure chamber row direction X and the pressure chamber row direction X 3rd active part S33 located in the one side part of the direction Y orthogonal to is deform | transformed so that it may warp in the direction away from pressure chamber 14Aa. The deformation of the second and third active portions S32 and S33 contributes to increasing the volume change of the pressure chamber 14Aa, and contributes to sucking a large amount of ink from the manifolds 14Da and 14Ea into the pressure chamber 14Aa.

  Then, when a ground potential is applied to the individual electrode 21 again, the first active portion S31 expands in the stacking direction Z toward the pressure chamber 14Aa and contracts in the directions X and Y orthogonal to the stacking direction Z. It projects and deforms in the direction inside the pressure chamber 14Aa. For this reason, the volume of the pressure chamber 14Aa decreases, the ink pressure increases, and ink is ejected from the nozzle holes 16a.

  When a ground potential is applied to the individual electrode 21 and the first active portion S31 is driven to discharge ink, both the individual electrode 21 and the first constant potential electrode 22G are at the ground potential, The third active portions S32 and S33 are in a voltage non-application state. Therefore, the second and third active portions S32, S33 return to a state where they do not expand and contract in any direction Z, X, Y. Therefore, when the first active portion S31 projects and deforms in the direction of the pressure chamber 14Aa (stacking direction Z), the second and third active portions S32 and S33 return to a state where they do not deform ( This is equivalent to contracting in the stacking direction Z and extending in two directions X and Y perpendicular to the stacking direction Z), so that the deformation of the first active part S31 is affected by the deformation of the second and third active parts S32. (See portions P1 and P2 in FIG. 4), and hardly reaches the pressure chamber 14Aa adjacent in the pressure chamber row direction X or the direction Y orthogonal thereto, and crosstalk is suppressed. That is, the deformation of the first active portion S31 (first portion) due to the switching between the application and non-application of the voltage to the first active portion S31 causes both sides of the pressure chamber 14Aa in the pressure chamber row direction X and the direction X thereof. Application and non-application of voltage to the second and third active portions S32 and S33 (second and third portions) so as to suppress propagation to the adjacent pressure chamber 14Aa on one side in the direction Y orthogonal to The application is switched.

  Thereafter, when the individual electrode 21 is returned to the same potential (positive potential) as that of the second constant potential electrode 23F, as described above, the first active portion S31 is not deformed, and the second and third active portions Since the portions S32 and S33 are deformed so as to warp away from the pressure chamber 14Aa, ink is sucked into the pressure chamber 14Aa from the manifolds 14Da and 14Ea.

  Due to such deformation of the first to third active portions S31 to S33, the ink ejection operation is repeated, and in each ejection operation, the volume change of the pressure chamber 14Aa is increased to increase the ejection efficiency, and in three directions. Crosstalk is suppressed.

  In the embodiment, since propagation to the adjacent pressure chamber 14Aa cannot be suppressed on the other side in the direction Y orthogonal to the pressure chamber row direction X (see the portion P3 in FIG. 39), the individual electrode 21 is The pressure chambers 14Aa adjacent to either side of the orthogonal direction Y are provided so as to have portions longer than the second constant potential electrode 23F on both sides as well as on one side of the orthogonal direction Y. It is also possible to suppress the propagation to.

  In this case, for example, as shown in FIGS. 44 to 47, the piezoelectric actuator 12 ′ has the orthogonal direction Y with respect to the central portion of the pressure chamber 14Aa in addition to the first to third active portions S31 to S33. 4 further includes a fourth active portion S34 corresponding to the other side portion. By forming the connection electrode 23Fa that connects each second constant potential electrode 23F closer to the central portion of the pressure chamber 14Aa in the direction Y than in the above-described embodiment, the individual electrode 21 can move in the direction Y. Not only on one side but also on the other side, it has a portion formed longer than the second constant potential electrode 23F (portions P12 and P13 in FIG. 44). This fourth active portion S34 (corresponding to the portion P13 in FIG. 44) is, similarly to the second and third active portions, a piezoelectric material sandwiched between the individual electrode 21 and the first constant potential electrode 22G. (Piezoelectric material layers 12a and 12b). Further, the first constant potential electrode 22G is formed on the entire surface.

  When a voltage is applied to the first active part S31, no voltage is applied to the fourth active part S34. On the other hand, when a voltage is not applied to the first active part S31, a voltage is applied to the fourth active part S34. When the voltage is applied by the voltage applying means, as in the second and third active portions S32 and S33, the layer extends in the stacking direction Z and in the directions X and Y orthogonal thereto. It is in a deformed state that contracts.

  Therefore, due to the fourth active portion S34, as in the second and third active portions S32 and S33, the influence of the deformation of the first active portion S31 causes cross-column crosstalk that propagates to the adjacent pressure chamber 14Aa. It is suppressed. Note that the area occupied by the fourth active part S34 is smaller than the area occupied by the third active part S33 in plan view, and therefore the fourth active part is slightly inferior to the third active part S33. The effect of suppressing inter-column crosstalk is also exhibited by S34.

  In this case, in the pressure chamber row direction X, two connection electrodes for connecting the second constant potential electrode 23F to the adjacent second constant potential electrode 23F in the pressure chamber row direction X are arranged on the same side. However, as shown in FIGS. 48 to 51, one connection electrode 23Faa can be arranged on one side of the direction Y, and the other connection electrode 23Fab can be arranged on the other side of the direction Y. is there. In this way, the active portion (corresponding to the portions P21 to P24 in FIG. 47) that cancels the influence of the deformation of the pressure chamber 14Aa can be formed in a well-balanced manner around the pressure chamber 14Aa in plan view. Thus, it is possible to more effectively form a portion that suppresses crosstalk. The portions P25 and P26 where the connection electrodes 23Faa and 23Fab are provided cannot exhibit the suppressing effect. Also in this embodiment, the inter-column crosstalk suppression effect by the fourth active portion S34 is slightly inferior to that of the third active portion S33, but the inter-column crosstalk is also increased by the fourth active portion S34. The suppression effect is exhibited.

In the twelfth embodiment, the third active portion is provided corresponding to one side in the direction orthogonal to the predetermined direction with respect to the central portion of the pressure chamber. For example, as shown in FIG. In the case where 14Aa ′ is provided to be inclined with respect to a direction orthogonal to the pressure chamber row direction X (predetermined direction), the third active portion is located on one side in the cross direction V corresponding to the inclination direction. Or third and fourth active portions on both sides.
(Example 13)
In this example, as shown in FIGS. 53 to 55, the piezoelectric material layers 12a and 12b are laminated in a vertical direction, and correspond to each pressure chamber 14Aa in plan view. Between the plurality of individual electrodes 21 provided, the first common constant potential electrode 22H sandwiching the piezoelectric material layers 12a and 12b between the individual electrodes 21, and the individual electrodes 21 having a plurality of openings 23Ga. And a second common constant potential electrode 23G sandwiching the piezoelectric material layer 12a. Then, a second common constant potential electrode 23G is formed between the two piezoelectric material layers 12a and 12b constituting the multilayer body, and one surface of the multilayer body (piezoelectric material layers 12a and 12b), that is, the upper side The individual electrode 21 is formed on the upper surface side of the piezoelectric material layer 12a, and the first common constant potential electrode 22H is formed on the other surface, that is, the lower surface side of the lower piezoelectric material layer 12b.

  Further, a plurality of first active portions are formed by a portion corresponding to the central portion of each individual electrode 21 in the piezoelectric material (piezoelectric material layers 12a and 12b) sandwiched between each individual electrode 21 and the first common constant potential electrode 22H. S41 is formed, and the second active portion S42 is formed by the piezoelectric material (piezoelectric material layer 12a) sandwiched between each individual electrode 21 and the second common constant potential electrode 23G.

  As shown in FIG. 55C, the piezoelectric actuator 12 corresponds to the pressure chamber 14Aa when the pressure chamber 14Aa is viewed in plan (when viewed from the stacking direction of the cavity unit 11 and the piezoelectric actuator 12). The first active part S41 (first part) provided and the second active part S42 (second part) corresponding to the outer peripheral side of the central part of the pressure chamber 14Aa are provided. Here, the central portion of the pressure chamber 14Aa is a portion located substantially in the center both in the pressure chamber row direction X in which the pressure chambers 14Aa are arranged and in the direction Y orthogonal thereto. That is, the second active portion S42 is formed around the first active portion S41. Further, the second active portion S42 is adjacent not only to the region corresponding to the inner portion (center portion side) of the outer peripheral edge 14Aaa of the pressure chamber 14Aa in the pressure chamber row direction X and the direction Y orthogonal thereto. It is set as the structure containing the area | region corresponding to beam part 14Ab and 14Ac which are the walls which partition pressure chamber 14Aa to fit.

  Further, the individual electrode 21 has a connection terminal portion 21a for applying a voltage by the voltage applying means disposed outside the region corresponding to the pressure chamber 14Aa when viewed in a plan view. Since the second common constant potential electrode 23G also has a portion that overlaps with the connection terminal portion 21a of the individual electrode 21 in plan view, the piezoelectric material layer 12a sandwiched between the overlapped portion and the connection terminal portion 21a. As a result, a part of the second active portion S42 is formed. In the adjacent pressure chamber rows, the individual electrodes 21 are formed by being shifted by a half pitch in the pressure chamber row direction X. Between these rows, the connection terminals ( The connection terminal portions 21a connected to (not shown) are formed in a staggered pattern.

  The opening 23Ga of the second common constant potential electrode 23G has a shape that is smaller than the pressure chamber 14Aa and follows the shape of the 14Aa pressure chamber in a plan view. In the chamber row direction X, they are shifted by a half pitch.

  In addition, a driver IC 90 that supplies a drive signal is electrically connected to each individual electrode 21 through the flexible wiring board 13 (signal line). The driver IC 90 and the flexible wiring board 13 constitute voltage applying means for applying a driving voltage to the first and second active portions S41 and S42 of the piezoelectric actuator 12.

  Specifically, in order to change the volume of the pressure chamber 14Aa, the individual electrode 21 is connected to the ground potential (first potential) and a positive potential (second potential: 20 V, for example) through the flexible wiring board 13. ) Is selectively given. The first common constant potential electrode 22H is always applied with a ground potential, and the second common constant potential electrode 23G is always applied with a positive potential.

  As described above, the piezoelectric actuator 12 has the individual electrodes 21 corresponding to the respective pressure chambers 14Aa, and a pressure potential is obtained by selectively applying a ground potential and a positive potential as drive signals to the individual electrodes 21. The configuration is such that ink is ejected from the nozzle holes 16a by changing the volume of 14Aa.

  More specifically, the individual electrode 21 is longer than the pressure chamber 14Aa in the pressure chamber row direction X and in the direction Y orthogonal thereto, as viewed in a plan view, and a region corresponding to the first active portion S41 and the second electrode. These regions are formed so as to occupy both the regions corresponding to the active portion S42. The first common constant potential electrode 22H is formed so as to occupy a region corresponding to the first active portion S41. The second common constant potential electrode 23G includes a region corresponding to the second active portion S42 in the plan view and a beam between adjacent pressure chambers 14Aa in the pressure chamber row direction X and the direction Y orthogonal thereto. It is formed so as to occupy a region corresponding to the portions 14Ab and 14Ac. That is, the second common constant potential electrode 23G extends to the region corresponding to the side of the pressure chamber row direction of the pressure chamber 14Aa including the region corresponding to the beam portion 14Ab, and is adjacent in the pressure chamber row direction X of the pressure chamber 14Aa. The two matching pressure chambers 14Aa and 14Aa are shared.

  As shown in FIGS. 55A and 55B, the first active portion S41 is deformed by applying a positive potential to the individual electrode 21 and applying a ground potential to the first common constant potential electrode 22H. Sometimes it is polarized in the same direction (polarization direction) as the direction of the voltage applied. On the other hand, the second active portion S42 is polarized in the same direction as the direction of the voltage applied when the individual electrode 21 is deformed by applying a ground potential and applying a positive potential to the second common constant potential electrode 23G. Has been. That is, the direction in which the voltage is applied and the polarization direction are the same. Here, in FIGS. 55A to 55C, the “effective when ON” portion is a portion to which a voltage (20 V) is applied when a positive potential is applied to the individual electrode 21. The portion “effective when OFF” corresponds to the second active portion to which a voltage (20 V) is applied when a ground potential is applied to the individual electrode 21.

  The first common constant potential electrode 22H is always a ground potential, and the second common constant potential electrode 23G is always a positive potential. A ground potential and a positive potential are selectively applied to the individual electrode 21 in order to change the volume of the pressure chamber 14Aa. Although the direction of voltage application is the same during polarization and during driving, the first common constant potential electrode 22H is always set to the ground potential (0V), and the second common constant potential electrode 23G is always set to a positive potential ( 20V: constant), and a positive potential (20V: constant) is applied to the individual electrode 21 or the application is canceled (see FIG. 56). Therefore, when a positive potential is applied to the individual electrode 21, a voltage is applied to the first active part S 41, but no voltage is applied to the second active part S 42, while a positive voltage is applied to the individual electrode 21. When the individual electrode 21 is set to the ground potential without being applied with the potential, the voltage is not applied to the first active portion S41 but the voltage is applied to the second active portion S42. Here, the voltage applied between the electrodes at the time of driving is smaller than the voltage applied at the time of polarization, so that deterioration due to repeated application of voltage between the electrodes is suppressed.

  By arranging the electrodes 21, 22 </ b> H, and 23 </ b> G in this manner, in the standby state, the individual electrode 21 is set to the ground potential by the voltage applying unit, so that the first active portion S <b> 411 has the same polarization direction. A voltage is applied in the direction, and the piezoelectric lateral effect expands in the stacking direction Z toward the pressure chamber 14Aa, contracts in the directions X and Y perpendicular to the stacking direction Z, and protrudes and deforms in the direction in the pressure chamber 14Aa. And On the other hand, since the top plate 15 is not affected by the electric field and does not spontaneously shrink, the top plate 15 is not perpendicular to the polarization direction between the piezoelectric material layer 12b located on the upper side and the top plate 15 located on the lower side. A difference is produced in the distortion. Combined with this, the top plate 15 is fixed to the cavity plate 14A, and as shown in FIG. 57 (b), the piezoelectric material layer 12b and the top plate 15 are convex toward the pressure chamber 14Aa. It will be in the state transformed so that (unimorph deformation).

  At the time of ink ejection, first, a positive potential is applied to the individual electrode 21 by the voltage applying means, and the first active portion S41 is not deformed in the pressure chamber row direction and the directions X and Y orthogonal thereto. It will be in a state that does not. At this time, the second active portion S42 is in a voltage application state, extends in the stacking direction Z (first direction) toward the pressure chamber 14Aa, and extends in the directions X and Y (second direction) orthogonal to the stacking direction Z. ), The second active portion S42 located on the side in the pressure chamber row direction is deformed so as to warp away from the pressure chamber 14Aa by the action of the top plate 15 as a restraining plate. As shown in FIG. 57A, the deformation of the second active portion S42 contributes to increasing the volume change of the pressure chamber 14Aa and sucks a large amount of ink from the manifolds 14Da and 14Ea into the pressure chamber 14Aa. To contribute.

  Then, the individual electrode 21 is set to the ground potential again, and a voltage is applied to the first active portion S41 in the same direction as the polarization direction, thereby projecting and deforming in the direction of the pressure chamber 14Aa as described above. It becomes a state to do. For this reason, the volume of the pressure chamber 14Aa decreases, the ink pressure increases, and ink is ejected from the nozzle holes 16a.

  When the voltage is applied to the first active portion S41, the second active portion S42 is in a voltage non-applied state, and therefore does not expand or contract in the stacking direction Z and the directions X and Y perpendicular to the stacking direction Z. Will return. Therefore, when the first active part S41 projects and deforms in the direction of the pressure chamber 14Aa (stacking direction Z), the second active part S42 returns to a state where it does not deform (this contracts in the stacking direction Z). (This is equivalent to extending in two directions X and Y orthogonal to the stacking direction Z), and as shown in FIG. 57 (a), the deformation of the first active portion S41 is affected by the second active portion S42. The pressure chambers 14Aa adjacent to each other (ie, the pressure chambers 14Aa adjacent to each other in the pressure chamber row direction X and the pressure chambers 14Aa adjacent to each other in the direction orthogonal to the pressure chamber row direction X) However, crosstalk is suppressed. That is, the second active portion S42 is configured to suppress the deformation of the first active portion S41 due to the switching between the application and non-application of the voltage to the first active portion S41 from propagating to the adjacent pressure chamber 14Aa. Switching between application and non-application of a voltage is performed.

  Thereafter, when the ink is ejected again, the individual electrode 21 is returned to the same potential (ground potential) as the first common constant potential electrode 22H, and as described above, the first active portion S41 is not deformed. Thus, the second active portion S42 is deformed so as to warp away from the pressure chamber 14Aa, and the volume of the pressure chamber 14Aa returns to the original volume, so that ink is sucked into the pressure chamber 14Aa from the manifolds 14Da and 14Ea. It will be.

  Thus, the deformation of the first active portion S41 and the second active portion S42 is repeated, and in each discharge operation, the volume change of the pressure chamber 14Aa is increased to increase the discharge efficiency and the crosstalk is suppressed. .

  In the above-described embodiment, the piezoelectric material layers 12a and 12b and the top plate 15 (restraining plate) have the same thickness. Therefore, when the piezoelectric actuator 12 including the top plate 15 is deformed, the neutral is not deformed. The surface is positioned at the intermediate portion in the thickness direction of the lower piezoelectric material layer 12b. Therefore, the deformation of the piezoelectric actuator 12 cannot be effectively used to deform the pressure chamber 14Aa and eject ink.

  Therefore, since the piezoelectric actuator 12 is laminated on the upper side of the cavity unit 11 via the top plate 15, as shown in FIGS. 58 and 59 (a) and 59 (b), the thickness of the top fret (restraint plate), If the thickness of the piezoelectric actuator 12 ′ (piezoelectric material layers 12a ′, 12b ′) is the same, the lower surface of the piezoelectric actuator 12 ′ (lower piezoelectric material layer 12b ′) is the first and second active portions S41. , S42 is transformed into a neutral surface that does not deform (a neutral surface that does not expand and contract in the plane), and the deformation of the piezoelectric actuator 12 '(first and second active portions S41, S42) is effectively utilized. Can do.

  Further, as in the above-described embodiment, it is not necessary to provide an individual electrode on the upper surface side of the upper piezoelectric material layer and a second common constant potential electrode on the lower surface side, and FIG. 60, FIG. 61, FIG. ) To (c), the second common constant potential electrode 23G may be formed on the upper surface side of the upper piezoelectric material layer 12a ′, and the individual electrode 21 may be formed on the lower surface side. . In this case, for wiring to the individual electrodes 21, through holes 24 filled with a conductive material are formed on the connection terminals 21a in the individual electrodes 21, and the connection terminals 21a of the individual electrodes 21 are connected to the connection terminals 21a. It is necessary to lead to the upper surface side of the upper piezoelectric material layer 12a ′. The first common constant potential electrode 22H is formed corresponding to the central portion of the individual electrode 21, and is connected to the connection electrode portion 22Ha extending in the pressure chamber row direction X. The connection electrode portion 22Ha is the first of them. The common constant potential electrode 22H is a common electrode.

  In this embodiment, the pressure chamber 14Aa has an oval shape and the individual electrode 21 has a rectangular shape in plan view. However, in the present invention, the shape of the pressure chamber and the individual electrode having the corresponding shape is the same. However, the present invention is not limited to this, and it can be formed as shown in FIGS. 63 (a) and 63 (b). The case shown in FIG. 63 (a) is a case where both the pressure chamber 14Aa ′ and the individual electrode are elliptical in plan view, and the pressure chamber 14Aa ′ is elliptical in the case shown in FIG. 63 (b). However, the individual electrode has an octagonal shape that is long in the longitudinal direction of the pressure chamber, and shows the relationship between the first active portion S41 and the second active portion S42.

In the above-described embodiment, a positive potential is applied to the second constant potential electrode. Therefore, as shown in the following embodiment 14, the second constant potential electrode is configured to reduce the impedance thereof. By reducing the voltage drop, it is possible to obtain the same discharge performance with respect to the nozzle communicating with any pressure chamber 14Aa.
(Example 14)
In the case of this example, as shown in FIGS. 64 to 67, when viewed in a plan view (that is, viewed from the stacking direction of the cavity unit 11 and the piezoelectric actuator 12), a plurality of pressure chambers corresponding to each pressure chamber 14Aa. A first common constant potential electrode 22K formed between the individual electrodes 21 and corresponding to the outer peripheral portion of each pressure chamber 14Aa and sandwiching the piezoelectric material layers 12a and 12b between the individual electrodes 21, and the individual electrodes 21. And a second common constant potential electrode 23K formed between the individual electrodes 21 and sandwiching the piezoelectric material layer 12a. That is, the second common constant potential electrode 23K is formed between the piezoelectric material layers 12a and 12b constituting the laminate, and the individual electrode 21 is formed on the upper surface (one surface) of the laminate (piezoelectric material layers 12a and 12b). Is formed so as to sandwich the piezoelectric material layer 12a together with the second common constant potential electrode 23K, and the first common constant potential electrode 22K and the piezoelectric material layer 12b together with the second common constant potential electrode 23K are formed on the lower surface (the other surface). Are formed so as to sandwich each other. Here, the central portion of the individual electrode 21 is a central portion in the pressure chamber row direction X in which the pressure chambers 14Aa are arranged (also in the nozzle row direction in which the nozzle holes 16a are arranged).

  The individual electrode 21 has a connection terminal portion 21a disposed outside the pressure chamber 14Aa, and a voltage is applied to the connection terminal portion 21a by the voltage applying means.

  The second common constant potential electrode 23K includes a plurality of first portions 23Ka extending in the pressure chamber row direction between adjacent pressure chamber rows, and these two adjacent first portions 23Ka are provided between the two adjacent first chamber portions 23Ka. A plurality of second portions 23Kb provided corresponding to the respective pressure chambers 14Aa, and these second portions 23Kb extend in a direction orthogonal to (intersect) the pressure chamber row direction. ing. Thus, the second common constant potential electrode 23K is formed in a net shape. The impedance is reduced. Therefore, the voltage drop is suppressed by reducing the impedance, and the same discharge performance can be obtained for the nozzles communicating with any of the pressure chambers 14Aa.

  The first common constant potential electrode 22K includes a plurality of third portions 22Ka extending in the pressure chamber row direction so as to overlap the plurality of pressure chambers 14Aa constituting the pressure chamber row. It has the 4th part 22Kb which connects the edge part of 3rd part 22Ka. The third portion 22Ka is provided not to overlap with the first portion 23Ka of the second common constant potential electrode 23K.

  A plurality of first active portions S51 formed of a piezoelectric material layer sandwiched between each individual electrode 21 and the second common constant potential electrode 23K (second portion 23Kb), each individual electrode 21 and each second electrode And a second active portion S52 formed by a piezoelectric material layer sandwiched between one common constant potential electrode 22K (third portion 22Ka). Here, since the second common constant potential electrode 23K involved in the formation of the first active portion S51 is formed in a net shape to reduce impedance, a voltage drop is suppressed in the second common constant potential electrode 23K. Thus, the same discharge performance can be obtained for the nozzles communicating with any of the pressure chambers 14Aa.

  A driver IC 90 for supplying a drive signal is electrically connected to each individual electrode 21 through the flexible wiring board 13 (signal line). The driver IC 90 and the flexible wiring board 13 constitute voltage applying means for applying a voltage to the first and second active portions S51 and S52 of the piezoelectric actuator 12.

  The piezoelectric actuator 12 changes the volume of the pressure chamber 14Aa by selectively applying a positive potential (first potential) and a ground potential (second potential) as drive signals to the individual electrodes 21. Ink is ejected from the nozzle hole 16a.

  More specifically, as shown in FIGS. 65 and 66, the individual electrode 21 has a rectangular shape in plan view, is longer than the pressure chamber 14Aa in the pressure chamber row direction X, and is orthogonal to the pressure chamber row direction X. In the direction Y, it is shorter than the pressure chamber 14Aa and is formed so as to occupy both of these regions across the region corresponding to the first active portion S51 and the region corresponding to the second active portion S52. The second common constant potential electrode 23K is formed so as to be shorter than the pressure chamber 14Aa in the pressure chamber row direction X and to occupy a region corresponding to the first active portion S51. The first common constant potential electrode 22K located on the pressure chamber 14Aa side is formed longer in the pressure chamber row direction X than the second common constant potential electrode 23K. That is, each individual electrode 21 is shared by the first and second common constant potential electrodes 22K and 23K.

  The first common constant potential electrode 22K is formed so as to occupy a region corresponding to the second active portion S52 and a region corresponding to the beam portion 14Ab between the adjacent pressure chambers 14Aa in the pressure chamber row direction X. . That is, the first common constant potential electrode 22K extends to a region corresponding to the side portion in the pressure chamber row direction X including the region corresponding to the beam portion 14Ab, and is shared by the pressure chambers 14Aa adjacent in the pressure chamber row direction X. Is done.

  Specifically, the first active portion S51 is formed by forming the individual electrode 21 on the upper surface side of the upper piezoelectric material layer 12a and forming the second common constant potential electrode 23K on the lower surface side. The second active portion S52 is formed by forming the first common constant potential electrode 22K on the lower surface side of the lower piezoelectric material layer 12b.

  Further, the electrodes 21, 22K, and 23K of the piezoelectric material layers 12a and 12b are arranged in the respective layers as shown in FIG. 66 when viewed in plan. That is, on the upper surface side (first layer) of the piezoelectric material layer 12a, the individual electrodes 21 are formed at a constant pitch in the pressure chamber row direction X corresponding to each pressure chamber 14Aa. The adjacent individual electrodes 21 are formed with a half-pitch shift in the pressure chamber row direction X, and are connected to connection terminals (not shown) of the flexible wiring board 13 of the individual electrodes 21 between these rows. The connecting terminal portions 21a are formed in a staggered pattern.

  On the lower surface side (second layer) of the piezoelectric material layer 12a, the second portion 23Kb of the second common constant potential electrode 23K is formed so as to correspond to each pressure chamber 14Aa. Both ends of the portion 23Kb are connected to the first portion 23Ka extending in the pressure chamber row direction between the pressure chamber rows adjacent to each other. Further, since the third portion 22Ka of the first common constant potential electrode 22K extends in the pressure chamber row direction between the two adjacent first portions 23Ka, the second common constant potential electrode The first portion 23Ka of 23K is not overlapped.

  In addition, as shown in FIG. 67, the first common common potential electrode 22K, 23K is connected to the first common potential electrode 22K, 23K, the first common at the center of the end of the actuator on the upper surface side of the piezoelectric material layer 12a. A connection terminal 26A is formed which is connected to the constant potential electrode 22K and is made conductive through a through hole filled with a conductive material. Both ends of the end portion are connected to the second common constant potential electrode 23K and filled with the conductive material. A connection terminal 26B that is conducted through the through-hole is formed.

  As shown in FIG. 64, in the first active part S51, the second potential (ground potential) is applied to the individual electrode 21, and the first potential (positive potential) is applied to the second common constant potential electrode 23K. Is polarized in the same direction (polarization direction) as the direction of the voltage applied when deformed. On the other hand, the second active portion S52 has the same voltage direction as that applied when the individual electrode 21 is deformed by applying the first electric potential to the individual common electrode 21 and applying the second electric potential to the first common constant potential electrode 22K. Polarized in the direction. That is, during the ink ejection operation, the direction in which the voltage is applied and the polarization direction are the same.

  The second common constant potential electrode 23K is always a positive potential, and the first common constant potential electrode 22K is always a ground potential. A positive potential and a ground potential are selectively applied to the individual electrode 21 in order to change the volume of the pressure chamber 14Aa. That is, the voltage application direction is the same during polarization and during driving, but the second common constant potential electrode 23K is always a positive potential, and the first common constant potential electrode 22K is always a ground potential. The positive potential is applied to the individual electrode 21 or the application of the positive potential is released to the ground potential. Therefore, when the individual electrode 21 is set to the ground potential, a voltage is applied to the first active portion S51, but no voltage is applied to the second active portion S52, while a positive potential is applied to the individual electrode 21. Is applied, no voltage is applied to the first active part S51, and a voltage is applied to the second active part S52. Here, the voltage applied between the electrodes at the time of driving is smaller than the voltage applied at the time of polarization, so that deterioration due to repeated application of voltage between the electrodes is suppressed.

  In the case where ink is ejected by arranging the electrodes 21, 22 </ b> K, and 23 </ b> K as described above, first, a ground potential is applied to the individual electrode 21 by the voltage applying unit. As a result, the first active portion S51 is applied with a voltage in the same direction as the polarization direction, and expands in the stacking direction Z (first direction) toward the pressure chamber 14Aa by the piezoelectric lateral effect. It contracts in the orthogonal directions X and Y (second direction), and enters a standby state in which it protrudes and deforms in the direction in the pressure chamber 14Aa (stacking direction Z).

  Subsequently, when the first potential (positive potential: 20 V) is applied to the individual electrode 21, the first active portion S51 does not expand or contract in the stacking direction Z and the directions X and Y orthogonal thereto, and does not deform. . At this time, the second active portion S52 is in a voltage application state, extends in the stacking direction Z (first direction) toward the pressure chamber 14Aa, and extends in the two directions X and Y (the second direction orthogonal to the stacking direction Z). The second active portions S52 and S52 located on both sides in the pressure chamber row direction X warp in the direction away from the pressure chamber 14Aa by the action of the top plate 15 as a restraining plate. It deforms as follows. The deformation of the second active portion S52 contributes to increasing the volume change of the pressure chamber 14Aa, and contributes to sucking a large amount of ink from the manifolds 14Da and 14Ea into the pressure chamber 14Aa.

  Then, when a ground potential is applied to the individual electrode 21 again, the first active portion S51 expands in the stacking direction Z toward the pressure chamber 14Aa and contracts in the directions X and Y perpendicular to the stacking direction Z. It projects and deforms in the direction in the pressure chamber 14Aa (stacking direction Z). For this reason, the volume of the pressure chamber 14Aa decreases, the ink pressure increases, and ink is ejected from the nozzle holes 16a.

  When a ground potential is applied to the individual electrode 21 and the first active portion S51 is driven and ink is ejected, both the individual electrode 21 and the first common constant potential electrode 22K are at the second potential, The second active portion S52 is in a voltage non-application state. Therefore, the second active portion S52 returns to a state in which it does not expand and contract in any direction Z, X, Y. Therefore, when the first active portion S51 projects and deforms in the direction of the pressure chamber 14Aa, the second active portion S52 returns to a state where it does not deform (this contracts in the stacking direction Z and This is equivalent to extending in two orthogonal directions X and Y), so that the influence of the deformation of the first active part S51 is suppressed by the deformation of the second active part S52, and the pressure chamber row direction Crosstalk is suppressed almost without reaching the adjacent pressure chamber 14Aa in X or the direction Y orthogonal thereto. That is, the deformation of the first active portion S51 (first portion) due to the switching between the application and non-application of the voltage to the first active portion S51 is caused by the pressure adjacent to both sides in the pressure chamber row direction X of the pressure chamber 14Aa. Application or non-application of voltage to the second active part S52 (second part) is switched so as to suppress propagation to the chamber 14Aa.

  Thereafter, when the individual electrode 21 is returned to the same potential (positive potential) as that of the second common constant potential electrode 23K, as described above, the first active portion S51 is not deformed, and the second active portion S52. Is deformed so as to warp away from the pressure chamber 14Aa, so that ink is sucked into the pressure chamber 14Aa from the manifolds 14Da and 14Ea.

  Due to the deformation of the first and second active portions S51 and S52, the ink discharge operation is repeated. In each discharge operation, the volume change of the pressure chamber 14Aa is increased to increase the discharge efficiency, and the crosstalk occurs. It is suppressed.

  In the case of this embodiment, the portion sandwiched between the connection terminal portion 21a of the individual electrode 21 and the second common constant potential electrode 23K arranged outside the pressure chamber 14Aa (girder portion 14Ab) in plan view. Since the (piezoelectric material layer 12a) also functions as the first active portion, the portion may act in a direction that suppresses deformation of the entire first active portion when ink is ejected. As described above, the second common constant potential electrode 23K can also be configured such that the portion overlapping the connection terminal portion 21a of the individual electrode 21 becomes an opening 23Kc (vacant space) in plan view. These openings 23Kc are formed in the first portion 23Ka.

  Further, the second portion 23Kb of the second common constant potential electrode 23K is provided in the direction Y orthogonal to the pressure chamber row direction X. However, the second portion 23Kb only needs to have a portion overlapping with the pressure chamber 14Aa. As shown, the second portion 23Kb ′ may be provided along the direction V inclined with respect to the pressure chamber row direction X. In the case of being inclined with respect to a direction orthogonal to the (predetermined direction), a third active part is provided on one side in the intersecting direction V corresponding to the inclined direction, or third on both sides. And a fourth active portion can be provided.

  In the above embodiment, the case where the droplet discharge device is an ink jet type recording device has been described. However, the present invention is not limited to this, and a colored liquid is applied as fine droplets or a conductive liquid is discharged. The present invention can also be applied to other droplet discharge devices that form wiring patterns.

  Further, not only recording paper but also various materials such as resin and cloth can be used as the recording medium, and not only ink but also various materials such as colored liquid and functional liquid can be applied as the liquid to be ejected.

FIG. 1A is a schematic configuration diagram showing a schematic configuration of an ink jet printer (droplet discharge device) according to the present invention, and FIG. 1B is a diagram of a cavity unit, a piezoelectric actuator, and a flexible wiring board (COP) according to the present invention. It is explanatory drawing which shows a relationship. It is a perspective view which shows the state which affixed the piezoelectric actuator on the upper side of the cavity unit. It is a figure which decomposes | disassembles a cavity unit into each plate which is a component, and shows them with a top plate. 1 is a schematic sectional view of Example 1. FIG. It is explanatory drawing of arrangement | positioning of the electrode in each piezoelectric material layer of a piezoelectric actuator. (A) and (b) respectively show the polarization direction, the effective portion when ON when applying voltage (first active portion), and the effective portion when OFF when no voltage is applied (first active portion). It is explanatory drawing which shows the relationship with 2 active part). (A) (b) is explanatory drawing which shows the volume change of a pressure chamber when a voltage is not applied and applied to a 1st active part, respectively. FIG. 5 is a view similar to FIG. 4 showing a modification of the first embodiment. FIG. 6 is a view similar to FIG. 4 for another modification of the first embodiment. FIG. 6 is a diagram similar to FIG. 4 for another modification of the first embodiment. (A) (b) is a figure similar to FIG. 6 (a) (b) about another modification (refer FIG. 10) of Example 1, respectively. FIG. 10 is a view similar to FIG. 4 for still another modified example of the first embodiment. (A) (b) is a figure similar to FIG. 6 (a) (b) about another modification (refer FIG. 12) of Example 1, respectively. FIG. 5 is a view similar to FIG. 4 for the second embodiment. FIG. 5 is a diagram similar to FIG. 4 for Example 3. FIG. 6 is a diagram similar to FIG. FIG. 10 is a diagram similar to FIG. (A) (b) is a figure similar to FIG. 7 (a) (b) about Example 5, respectively. FIG. 10 is a diagram similar to FIG. FIG. 10 is a view similar to FIG. FIG. 10 is a view similar to FIG. (A) (b) is a figure similar to FIG. 6 (a) (b) about Example 7, respectively. FIG. 10 is a diagram similar to FIG. FIG. 10 is a diagram similar to FIG. 5 for Example 8. FIGS. 6A and 6B are views similar to FIGS. 6A and 6B, respectively, regarding Example 8. FIGS. (A) (b) is a figure similar to FIG. 7 (a) (b) about Example 8, respectively. (A) and (b) are timing charts, respectively. FIG. 10 is a diagram similar to FIG. FIG. 10 is a diagram similar to FIG. 5 for Example 9. FIGS. 6A and 6B are views similar to FIGS. 6A and 6B, respectively, regarding Example 9. FIG. (A) (b) is the same figure as Example 7 (a) and (b) about Example 9, respectively. It is the same figure as FIG. 4 about Example 10. FIG. (A) (b) is the same figure as Example 10 (a) and (b) about Example 10, respectively. (A) (b) is a figure similar to FIG. 7 (a) (b) about Example 10, respectively. It is the same figure as FIG. 4 about Example 11. FIG. FIG. 10 is a diagram similar to FIG. 5 for Example 11. (A) and (b) are the figures similar to FIG. 6 (a) (b) about Example 11, respectively. (A) (b) is the same figure about Example 11 as FIG. 7 (a) (b), respectively. It is explanatory drawing of arrangement | positioning of the electrode in each piezoelectric material layer of the piezoelectric actuator in Example 12. FIG. It is a figure which shows arrangement | positioning of an electrode for every piezoelectric material layer. It is sectional drawing in the AA of FIG. It is sectional drawing in the BB line of FIG. It is sectional drawing in the CC line of FIG. It is a figure similar to FIG. 39 about a modification. It is a figure which shows arrangement | positioning of an electrode for every piezoelectric material layer. It is sectional drawing in the DD line | wire of FIG. It is sectional drawing in the FF line of FIG. It is a figure similar to FIG. 39 about another modification. It is a figure which shows arrangement | positioning of an electrode for every piezoelectric material layer. It is sectional drawing in the GG line of FIG. It is sectional drawing in the HH line of FIG. It is explanatory drawing of a crossing direction. 14 is a schematic sectional view of Example 13. FIG. It is explanatory drawing of arrangement | positioning of the electrode in each piezoelectric material layer of a piezoelectric actuator. (A), (b), and (c) are the polarization direction for Example 13, the effective part when ON (first active part) when applying voltage, and the effective when OFF when applying no voltage. It is explanatory drawing which shows the relationship with a part (2nd active part). It is a timing chart figure. (A) (b) is explanatory drawing which shows the volume change of a pressure chamber when a voltage is not applied and applied to a 1st active part, respectively. FIG. 54 is a view similar to FIG. 53 for a modified example of the thirteenth embodiment. (A) (b) is a figure similar to FIG. 55 (a) (b) about a modification, respectively. FIG. 57 is a view similar to FIG. 53 for still another modification example of the thirteenth embodiment. (A) (b) is a figure similar to FIG. 54 about said another modification, respectively. (A) (b) (c) is a figure similar to FIG. 55 (a) (b) (c) about said another modification, respectively. (A) (b) is explanatory drawing about the modification of the shape of a pressure chamber, respectively. FIG. 16 is a cross-sectional view showing the arrangement of electrodes in each piezoelectric material layer of the piezoelectric actuator of Example 14. It is a figure which shows arrangement | positioning of an electrode for every piezoelectric material layer. It is a figure which shows an electrode for every piezoelectric material layer. It is a figure which shows the electrode pattern for every piezoelectric material layer. It is a figure which shows arrangement | positioning of an electrode for every piezoelectric material layer about the modification of Example 14. FIG. It is a schematic sectional drawing about a prior art example. It is explanatory drawing which shows the relationship between the polarization direction, the effective part at the time of voltage application, and the effective part at the time of voltage non-application about a conventional row | line | column. It is explanatory drawing which shows the volume change of a pressure chamber when a voltage is applied to the active part of a prior art example.

Explanation of symbols

S11, S12, S13 1st active part S21, S22 2nd active part 1 Inkjet printer 3 Inkjet head 12 Piezoelectric actuator 12a-12c Piezoelectric material layer 14Aa Pressure chamber 14Ab Digit part 21 Individual electrode 22, 22A, 22B First Constant potential electrode 23 Second constant potential electrode 24 Through hole

Claims (16)

A droplet discharge head in which a piezoelectric actuator for selectively discharging a liquid in each pressure chamber is bonded to a cavity unit in which a plurality of pressure chambers are regularly formed;
A liquid droplet ejection apparatus comprising a voltage application means for applying a voltage to the piezoelectric actuator,
The piezoelectric actuator includes a first active portion corresponding to a central portion of the pressure chamber, and a second active portion corresponding to a portion on the outer peripheral side of the central portion of the pressure chamber,
Each of the first active portion and the second active portion expands in a first direction toward the pressure chamber and is orthogonal to the first direction when a voltage is applied by the voltage applying means. Configured to be in a deformed state that contracts in the second direction,
The voltage applying means does not apply a voltage to the second active part when a voltage is applied to the first active part, while the second active part does not apply a voltage to the first active part. A liquid droplet ejection apparatus for applying a voltage to a portion.   The liquid droplet ejection apparatus according to claim 1, wherein the second active portion includes a region inside an outer peripheral edge of the pressure chamber. The first active portion is sandwiched between an individual electrode to which a first potential and a second potential different from the first potential are selectively applied, and a first constant potential electrode to which the first potential is applied. A piezoelectric material comprising
The second active portion includes a piezoelectric material sandwiched between the individual electrode and a second constant potential electrode to which the second potential is applied. The droplet discharge device according to 1 or 2. The individual electrode is formed so as to occupy both the region corresponding to the first active portion and the region corresponding to the second active portion,
The first constant potential electrode is formed to occupy a region corresponding to the first active portion,
The liquid droplet ejection apparatus according to claim 1, wherein the second constant potential electrode is formed so as to occupy at least a region corresponding to the second active portion. The first active part is polarized in the same direction as a voltage applied when the second potential is applied to the individual electrode and the first potential is applied to the first constant potential electrode. Has been
The second active part is polarized in the same direction as the voltage applied when the first potential is applied to the individual electrode and the second potential is applied to the second constant potential electrode. The liquid droplet ejection apparatus according to claim 3, wherein the liquid droplet ejection apparatus is provided.   6. The droplet discharge device according to claim 3, wherein the first potential is a positive potential and the second potential is a ground potential.   6. The liquid droplet ejection apparatus according to claim 3, wherein the first potential is a ground potential, and the second potential is a positive potential.   The liquid droplet ejection apparatus according to claim 7, wherein the second constant potential electrode is shared with the adjacent pressure chamber. The piezoelectric actuator has at least one piezoelectric material layer,
By forming the individual electrode on one surface side of the piezoelectric material layer and forming the first constant potential electrode and the second constant potential electrode on the other surface side, the first active portion and 8. The droplet discharge device according to claim 7, wherein the second active portion is formed in the same piezoelectric material layer.   10. The first constant potential electrode and the second constant potential electrode formed on the other surface side are separated with an insulating layer thinner than the piezoelectric material layer interposed therebetween. The droplet discharge device according to 1.   The droplet ejection apparatus according to claim 10, wherein the insulating layer is made of the same material as the piezoelectric material layer. The first constant potential electrode is formed so as to be in a row with two adjacent pressure chambers,
The liquid droplet ejection apparatus according to claim 7, wherein the second constant potential electrode is formed only on one side of the two pressure chambers. The piezoelectric actuator has a plurality of piezoelectric material layers,
The first constant potential electrode or the second constant potential electrode is the farthest distance that is the surface of the plurality of piezoelectric material layers that is farthest from the pressure chamber and that is the surface opposite to the pressure chamber. Formed on the surface,
The individual electrode is formed on any surface of the piezoelectric material layers and on a surface different from the most distant surface,
A surface electrode serving as an input terminal to the individual electrode is formed in a region outside the outer peripheral edge of the pressure chamber of the most spaced surface,
6. The droplet discharge device according to claim 3, wherein the individual electrode is electrically connected to the surface electrode through a through hole penetrating the piezoelectric material layer. The second active portion is formed in a layer other than the most spaced layer of the plurality of piezoelectric material layers,
14. The liquid droplet ejection apparatus according to claim 13, wherein the surface electrode is formed in a region between the adjacent pressure chambers. A droplet discharge head in which a piezoelectric actuator for selectively discharging a liquid in each pressure chamber is joined to a cavity unit in which a plurality of pressure chambers are regularly formed;
A droplet discharge device comprising a voltage applying means for applying to the piezoelectric actuator,
The piezoelectric actuator includes a first portion located corresponding to a central portion of the pressure chamber, and a second portion located corresponding to a portion on the outer peripheral side of the central portion of the pressure chamber,
The voltage application means switches between application and non-application of voltage to the first portion in order to change the volume of the pressure chamber, and the deformation of the first portion due to this change propagates to the adjacent pressure chamber. In order to suppress this, the application of the voltage to the second part is switched between non-application, and when the voltage is applied to the first part, the voltage is not applied to the second part, A droplet discharge apparatus, wherein a voltage is applied to the second portion when no voltage is applied to the first portion . A droplet discharge head in which a piezoelectric actuator for selectively discharging liquid in each pressure chamber is joined to a cavity unit in which a plurality of pressure chambers are regularly formed,
The piezoelectric actuator is
A first active portion corresponding to a central portion of the pressure chamber;
A second active portion corresponding to a portion on the outer peripheral side of the central portion of the pressure chamber;
A first potential and a second potential different from the first potential are selectively applied across the region corresponding to the first active portion and the region corresponding to the second active portion. Individual electrodes to be
A first constant potential electrode formed to occupy a region corresponding to the first active portion and to which the first potential is applied;
A droplet discharge head comprising: a second constant potential electrode formed to occupy at least a region corresponding to the second active portion and to which a second potential different from the first potential is applied. .