JP2011110897A - Liquid discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress destruction of a piezoelectric actuator by acting external force on an ink jet head. <P>SOLUTION: In the ink jet head 1, a flow channel unit 2, the piezoelectric actuator 3 and a flexible cable 4 are laminated and joined, a pressure chamber 10 is formed in a position opposite to a first surface electrode 20 connected to an individual electrode 22 of the flow channel unit 2, and a recessed part 12 is formed in a position opposite to a second surface electrode 21 connected to a common electrode 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejection device that ejects liquid.

  2. Description of the Related Art Conventionally, as a liquid ejection device that ejects liquid, for example, there is an inkjet head mounted on an inkjet printer. Such an ink jet head includes a flow path unit and an actuator, and the actuator applies pressure to the ink in the pressure chamber formed in the flow path unit, thereby ejecting ink from the nozzles.

  The actuator described in Patent Document 1 is a piezoelectric actuator formed by laminating a piezoelectric sheet, individual electrodes to which a drive voltage is applied, and a common electrode held at a ground voltage. The individual electrodes of the piezoelectric actuator are arranged at positions facing the pressure chambers of the flow path unit, and the common electrode is arranged facing the plurality of individual electrodes.

  When ink is ejected from the inkjet head, a drive voltage is applied to the individual electrode from the control substrate connected to the piezoelectric actuator via the flexible cable, and an electric field is generated between the individual electrode and the common electrode. The piezoelectric sheet sandwiched between these electrodes is piezoelectrically deformed. Along with this piezoelectric deformation, the volume of the pressure chamber changes, pressure is applied to the ink in the pressure chamber, and ink is ejected.

JP 2003-80709 A

  Since the piezoelectric actuator is formed by stacking the piezoelectric sheet and the electrode as described above, the piezoelectric actuator is thicker in the region where the individual electrode is disposed than in the region where the individual electrode is not disposed. . In addition, since the individual electrode and the common electrode are connected to the flexible flat cable via the surface electrode disposed on the surface of the piezoelectric actuator, the surface electrode is disposed on the surface orthogonal to the piezoelectric sheet and electrode stacking direction of the piezoelectric actuator. In the case where the surface electrode is disposed, the thickness of the piezoelectric actuator also increases.

  When an external force acts on the piezoelectric actuator, the external force is concentrated in a region where the piezoelectric actuator is thick. At this time, in the flow path unit, a pressure chamber is formed at a position facing the individual electrode of the piezoelectric actuator, but a pressure chamber is formed at a position facing the surface electrode connected to the common electrode. Absent. Therefore, the region where the surface electrode connected to the individual electrode of the piezoelectric actuator is deformed to the pressure chamber side, but the region where the surface electrode connected to the common electrode is not deformable, so external force is applied to this region. You will concentrate. When external force concentrates on the piezoelectric sheet, which is a brittle material, the piezoelectric sheet may crack and the piezoelectric actuator may be destroyed.

  Therefore, an object of the present invention is to provide a liquid ejection device that does not break a piezoelectric actuator even when an external force is applied to the piezoelectric actuator.

  A liquid ejection apparatus according to a first aspect of the present invention is a liquid ejection apparatus comprising a nozzle, a flow path unit having a pressure chamber communicating with the nozzle, and a piezoelectric actuator that covers the pressure chamber and is joined to the flow path unit. The piezoelectric actuator is formed by laminating a piezoelectric sheet and a plurality of types of electrodes, and at least one of the plurality of types of electrodes is disposed in a partial region of the piezoelectric sheet. The piezoelectric actuator has regions with different thicknesses in the surface direction of the piezoelectric actuator, and the pressure chamber or the recess is in a region facing the region of the flow path unit where the thickness of the piezoelectric actuator is thick. It is characterized by being formed.

  According to this, since the pressure chamber or the recess is formed in the region facing the region where the thickness of the piezoelectric actuator of the flow path unit is thick, the region where the thickness of the piezoelectric actuator is thick even if an external force is applied to the piezoelectric actuator. It can be deformed so as to bend toward the flow path unit. Therefore, it is possible to reduce the external force acting on the region where the thickness of the piezoelectric actuator is thick, and to suppress the destruction of the piezoelectric actuator.

  In the liquid ejection device according to a second aspect of the present invention, in the first aspect, the pressure chamber and the concave portion are formed on a surface that contacts the piezoelectric actuator of the flow path unit, and the surface is perpendicular to the surface. The cross-sectional area of the recess is smaller than the cross-sectional area of the pressure chamber.

  According to this, it is possible to provide a liquid ejection device that can guide the adhesive that bonds the piezoelectric actuator and the flow path unit to the concave portion by capillary action, and can suppress the protrusion of the adhesive.

  In the liquid ejection device according to a third aspect of the present invention, in the first or second aspect, the piezoelectric actuator is formed by stacking a piezoelectric sheet, an individual electrode, and a common electrode, and the individual electrode is formed on a surface of the piezoelectric actuator. The pressure chamber is formed in a region facing the first surface electrode of the flow path unit, the first surface electrode connected to the common electrode and the second surface electrode connected to the common electrode. The concave portion is formed in a region facing the second surface electrode of the path unit.

  According to this, in the region where the first surface electrode and the second surface electrode are arranged, the thickness of the piezoelectric actuator is increased, but a pressure chamber or a recess is formed in the region facing the surface electrode of the flow path unit. Therefore, it is possible to suppress the destruction of the region where the surface electrode of the piezoelectric actuator is disposed.

  According to a fourth aspect of the present invention, there is provided the liquid ejection device according to the third aspect, wherein the second surface electrode and a plurality of the concave portions facing the second surface electrode are provided, and the piezoelectric actuator of the flow path unit is provided. A connection groove for communicating the plurality of recesses with each other is formed on a surface that contacts the surface.

  According to this, there is a bias in the distribution of the adhesive that bonds the piezoelectric actuator and the flow path unit, and even if the adhesive is concentrated in any one of the plurality of recesses, the recesses communicate with each other by the connection grooves. Therefore, it is possible to provide a liquid ejection device that can effectively suppress the protrusion of the adhesive.

  According to a fifth aspect of the present invention, in the liquid ejecting apparatus according to the fourth aspect, the second electrode is disposed on a surface opposite to a surface of the piezoelectric actuator that contacts the flow path unit. It is arranged in a region on the outer peripheral side of the region, and the recess is formed across the region where the piezoelectric actuator abuts and the region outside the region on the surface abutting the piezoelectric actuator of the flow path unit. The connection groove is formed in a region outside the region where the piezoelectric actuator abuts on the surface of the channel unit that abuts on the piezoelectric actuator.

  According to this, since the adhesive for bonding the piezoelectric actuator and the flow path unit can be captured by the concave portion and the connection groove on the outer peripheral side of the piezoelectric actuator, it is possible to provide a liquid ejection device that can effectively suppress the protrusion of the adhesive. Can do.

  In the liquid ejection device according to a sixth aspect of the present invention, in any one of the third to fifth aspects, the region where the second surface electrode of the piezoelectric actuator is disposed is between the common electrode and the second surface electrode. A plurality of the piezoelectric sheets are laminated on each other, and through holes are formed in each of the plurality of piezoelectric sheets. The second surface electrode is electrically connected to the common electrode by a conductive material filled in the through holes. In addition, an auxiliary electrode is formed between the piezoelectric sheets of the plurality of piezoelectric sheets so that the through holes are electrically connected to each other.

  According to this, since the auxiliary electrode is formed, the piezoelectric actuator is thick in the region where the auxiliary electrode is formed, and the necessity of forming a recess in the region facing this region of the flow path unit is increased.

  According to a seventh aspect of the present invention, in the sixth aspect, the auxiliary electrode is formed over the entire outer peripheral region of the piezoelectric actuator.

  According to this, since the auxiliary electrode also reinforces the outer peripheral region of the piezoelectric actuator, the thickness of the outer peripheral region of the piezoelectric actuator is increased, and there is a need to form a recess in the region facing this region of the flow path unit. In addition, since the adhesive can be captured on the outer peripheral side of the piezoelectric actuator, it is possible to provide a liquid ejection device that can effectively suppress the protrusion of the adhesive.

  The liquid ejection device according to the present invention can reduce the concentration of an external force in a region where the thickness of the piezoelectric actuator is thick even if an external force is applied to the piezoelectric actuator, and suppress the destruction of the piezoelectric actuator. Can do.

It is a disassembled perspective view of the inkjet head which concerns on this embodiment. (A) It is the sectional view on the A-A 'line of FIG. FIG. 2B is a sectional view taken along line B-B ′ in FIG. 1. It is sectional drawing of the inkjet head which concerns on this embodiment. It is a disassembled perspective view of the piezoelectric actuator which concerns on this embodiment. FIG. 5 is a sectional view taken along line C-C ′ of FIG. 4. It is a disassembled perspective view of the piezoelectric actuator which concerns on a 1st modification. It is sectional drawing of the inkjet head which concerns on a 2nd modification. It is sectional drawing of the inkjet head which concerns on a 3rd modification.

  Next, a preferred embodiment of the present invention will be described. In the present embodiment, the present invention is applied to an ink jet head of an ink jet printer that records an image or the like by ejecting ink onto a recording sheet as a liquid ejecting apparatus.

  FIG. 1 is an exploded perspective view of an ink jet head according to the present embodiment. As shown in FIG. 1, the inkjet head 1 is formed by laminating and joining a flow path unit 2, a piezoelectric actuator 3, and a flexible cable 4.

  As shown in FIG. 2, the flow path unit 2 is formed by laminating a cavity plate 6, a base plate 7, a manifold plate 8, and a nozzle plate 9 that are metal plates.

  In the cavity plate 6, a pressure chamber 10, an ink supply port 11, a recess 12, and a connection groove 13 are formed so as to be open to the surface in contact with the piezoelectric actuator 3. The pressure chambers 10 have a substantially oval shape and form a row corresponding to one ink supply port 11, and four rows of pressure chambers 10 are formed corresponding to the four ink supply ports 11. In addition, in a region outside the plurality of pressure chambers 10, a plurality of recesses 12 and connection grooves 13 that allow these recesses 12 to communicate with each other are formed. The connection groove 13 is formed in a region outside the region where the piezoelectric actuator 3 is joined. The recess 12 and the connecting groove 13 are smaller in width and depth than the pressure chamber 10, and the cross-sectional area of the cross section parallel to the width direction and the depth direction is smaller than the cross-sectional area of the pressure chamber 10. If the cross-sectional area of the recess 12 and the connection groove 13 is smaller than the cross-sectional area of the pressure chamber 10, either the width or the depth may be larger than the pressure chamber 10.

  The base plate 7 is formed with communication holes 15 and 16 communicating with both ends of the pressure chamber 10.

  The manifold plate 8 is formed with a common liquid chamber 14 and a communication hole 17. The common liquid chamber 14 communicates with the ink supply port 11 and is formed to extend in the column direction of the pressure chambers 10 arranged corresponding to the one ink supply port 11, and corresponds to the ink supply port 11. Four are formed. The common liquid chamber 14 communicates with the plurality of pressure chambers 10 through the communication holes 15. The communication hole 17 communicates with the communication hole 16 of the base plate 7 and further communicates with a nozzle 18 described later.

  In the nozzle plate 9, nozzles 18 corresponding to the plurality of pressure chambers 10 are formed. Thus, an ink flow path from the ink supply port 11 to the nozzle 18 is formed in the flow path unit 2. Ink is supplied to the flow path unit 2 from an external ink cartridge (not shown) connected to the ink supply port 11. At this time, ink cartridges storing inks of four colors of black, cyan, magenta, and yellow are connected to the respective ink supply ports 11 to supply ink. The ink supplied to the flow path unit 2 may be any type of ink, and all may be supplied with the same type of ink.

  2 to 5, the piezoelectric actuator 3 is formed by laminating a plurality of piezoelectric sheets 25 made of a piezoelectric material. An individual electrode 22, a common electrode 23, and an auxiliary electrode 24 are disposed between the piezoelectric sheets 25. A common electrode 23 is formed on the surface of the piezoelectric actuator 3 that contacts the flow path unit 2, and the first surface electrode 20 and the second surface electrode are formed on the surface of the piezoelectric actuator 3 that contacts the flexible cable 4. 21 is formed. When viewed from the thickness direction of the piezoelectric actuator 3, the piezoelectric sheet 25 in a region where the individual electrode 22 and the common electrode 23 overlap is polarized in the thickness direction.

  The first surface electrode 20 is electrically connected to the individual electrode 22 through an electrode material filled in a through hole (not shown). Further, as shown in FIG. 5, the second surface electrode 21 is electrically connected to the common electrode 23 through an electrode material filled in the through hole 26. At this time, if the through holes are created at the same position of the piezoelectric sheets 25 adjacent to each other, when the piezoelectric actuators 3 are manufactured, if the piezoelectric sheets 25 are misaligned, the through holes may not be conducted. Therefore, the auxiliary electrode 24 is disposed between the adjacent piezoelectric sheets 25, and the through holes are electrically connected to each other via the auxiliary electrode 24, thereby improving the reliability of the electrical connection between the through holes.

  In the piezoelectric actuator 3, the thickness of the region where the first surface electrode 20 and the individual electrode 22 are arranged is substantially the same as the thickness of the region where the second surface electrode 21 and the auxiliary electrode 24 are arranged. The area is thinner than the above area.

  In the flexible cable 4, a driver IC 30, connection terminals 31, and a plurality of wirings (not shown) are arranged on a resin substrate. The connection terminal 31 is a terminal for connecting to a power supply that supplies power to the driver IC 30. Wiring is arranged from the connection terminal 31 toward the driver IC 30, and the connection terminal 31 and the driver IC 30 are electrically connected. In addition, wiring for connecting to the surface electrodes 20 and 21 of the piezoelectric actuator 3 is arranged from the driver IC 30 toward the end of the flexible cable 4 opposite to the connection terminal 31.

  As shown in FIG. 3, the flow path unit 2, the piezoelectric actuator 3, and the flexible cable 4 are stacked and joined to form the ink jet head 1. At this time, in the flow path unit 2, the pressure chamber 10 is formed at a position facing the first surface electrode 20 and the individual electrode 22 of the piezoelectric actuator 4, and the second surface electrode 21 and the auxiliary electrode of the piezoelectric actuator 4 are formed. A recess 12 is formed at a position facing 24. A plurality of wirings of the flexible cable 4 are electrically connected to the surface electrodes 20 and 21, respectively.

  In this ink jet head 1, when an external force acts on the piezoelectric actuator 3, the external force concentrates on a region where the thickness of the piezoelectric actuator 3 is thick, but faces the first surface electrode 20 and the individual electrode 22 of the flow path unit 2. The pressure chamber 10 is formed in the region to be formed, and the concave portion 12 is formed in the region facing the second surface electrode 21 and the auxiliary electrode 24, so that the piezoelectric actuator 3 has a thick region. It is deformed so as to bend toward the flow path unit 2. Therefore, the external force acts uniformly on the surface where the surface electrodes 20 and 21 of the piezoelectric actuator 3 are arranged, and it is possible to suppress the concentration of the external force in a region where the thickness of the piezoelectric actuator 3 is thick. .

  Further, the common electrode 23 on the surface of the piezoelectric actuator 3 that contacts the flow path unit 2 not only serves as an electrode for piezoelectrically deforming the piezoelectric actuator 3, but also functions to isolate the ink in the pressure chamber 10 from the piezoelectric sheet 25. Have.

  Next, a method for manufacturing the inkjet head 1 will be described.

  The flow path unit 2 forms holes serving as ink flow paths such as the pressure chambers 10 in the respective plates 6 to 9 by etching or laser processing. Then, these plates 6-9 are laminated | stacked and it joins with an adhesive agent, and the flow-path unit 2 is formed. In joining the plates 6 to 9, other joining methods such as metal diffusion joining may be used in addition to the adhesive.

  The piezoelectric actuator 3 is formed by printing patterns of surface electrodes 20, 21, individual electrodes 22, common electrodes 23, and reinforcing electrodes 24 on a plurality of green sheets made of a piezoelectric material, and laminating and firing these green sheets. Thus, the piezoelectric sheet 25 is used to form the piezoelectric actuator 3. The surface electrodes 20 and 21 and the common electrode 23 on the surface in contact with the flow path unit 2 may be formed on the piezoelectric sheet 25 by printing after firing the green sheet. The method for forming the electrodes is not limited to printing, and any method such as sputtering may be used. Furthermore, the method for forming the piezoelectric actuator 3 is not limited to firing the green sheet, and any method such as an AD method, a sol-gel method, or vapor deposition may be used.

  Thereafter, the flow path unit 2 and the piezoelectric actuator 3 are joined. First, an adhesive is applied to the surface of the piezoelectric actuator 3 that contacts the flow path unit 2, and then the first surface electrode 20 faces the pressure chamber 10 and the second surface electrode 21 faces the recess 12. The flow path unit 2 and the piezoelectric actuator 3 are aligned and pressed together to join. When pressing is started, the pressing force concentrates on the thick region of the piezoelectric actuator 3, but the pressure chamber 10 and the recess 12 are formed at a position facing the region of the flow path unit 2. The region is deformed so as to bend toward the flow path unit 2. As a result, the surface of the piezoelectric actuator 3 on which the surface electrodes 20 and 21 are formed is uniformly pressed over the entire surface, and the pressing force is not concentrated on the thick region of the piezoelectric actuator 3. The piezoelectric actuator 3 can be prevented from being destroyed.

  Furthermore, since the recess 12 and the connection groove 13 are smaller in width and depth than the pressure chamber 10 and the cross-sectional area of the cross section parallel to the width direction and the depth direction is smaller than the cross-sectional area of the pressure chamber 10, Of the adhesive applied to the piezoelectric actuator 3, the surplus that is not used for bonding flows into the recess 12 and the connection groove 13 by capillary action. That is, the recess 12 and the connection groove 13 also have a function as an adhesive escape groove. Thereby, it is possible to suppress the adhesive from flowing into the pressure chamber 10.

  Furthermore, even if the adhesive applied to the piezoelectric actuator 3 is not uniform and excessive adhesive is concentrated in any of the recesses 12, the plurality of recesses 12 communicate with each other through the connection grooves 13. The adhesive can be reliably captured.

  Also, if the surplus adhesive reaches the upper surface of the piezoelectric actuator 3, the first surface electrode 20 and the second surface electrode 21, or the plurality of first surface electrodes 20 are electrically connected via the adhesive. As a result, the piezoelectric actuator 3 is destroyed. However, since the recess 12 and the connection groove 13 are formed in a region outside the outer shape of the piezoelectric actuator 3 when the flow path unit 2 and the piezoelectric actuator 3 are joined, they protrude outside the piezoelectric actuator 3. The adhesive does not reach the upper surface along the side surface of the piezoelectric actuator 3, and the piezoelectric actuator 3 can be prevented from being broken.

  Thereafter, the piezoelectric actuator 3 and the flexible cable 4 are joined. Solder bumps are formed on the surface electrodes 20, 21, and the piezoelectric actuator 3 and the flexible cable 4 bonded to the flow path unit 2 are stacked and pressed against each other while being heated, thereby wiring the surface electrodes 20, 21 and the flexible cable 4. And the piezoelectric actuator 3 and the flexible cable 4 are joined. This pressing also applies a pressing force to the surface electrodes 20 and 21 as described above, but in the flow path unit 2, the pressure chamber 10 and the groove 12 are formed at a position facing the surface electrodes 20 and 21. The region where the surface electrodes 20 and 21 are formed is deformed so as to bend toward the flow path unit 2. Thereby, pressing force does not concentrate on the said area | region, but it can suppress that the piezoelectric actuator 3 is destroyed. The solder bumps may be formed on the wiring of the flexible cable 4.

  Next, modified embodiments in which various changes are made to the present embodiment will be described. However, the same reference numerals are given to those having the same configuration as in the above embodiment, and the description thereof is omitted as appropriate. 7 and 8, the illustration of the flexible cable 4 is omitted.

  As shown in FIG. 6, the first variation is that the auxiliary electrode 24 for increasing the reliability of electrical connection between through-holes (not shown) for conducting the second surface electrode 21 and the common electrode 23 is provided on the piezoelectric actuator 3. It is arrange | positioned in the outer peripheral region whole region.

  When the piezoelectric actuator 3 is manufactured, a plurality of green sheets are laminated and fired, but in order to form the plurality of piezoelectric actuators 3 at the same time, the green sheets are fired and then the piezoelectric sheet 25 is cut. Thus, a plurality of piezoelectric actuators 3 are formed. At this time, since the piezoelectric material is a brittle material, when the piezoelectric actuator 3 is cut out, the piezoelectric sheet 25 in the outer peripheral region of the piezoelectric actuator 3 may be chipped. However, since the auxiliary electrode 24 is disposed over the entire outer peripheral region of the piezoelectric actuator 3, the outer peripheral region of the piezoelectric actuator 3 is reinforced by the auxiliary electrode 24 made of a metal material that is a ductile material. It is possible to suppress chipping.

  In the second modification, as shown in FIG. 7, the second surface electrode 21 and the auxiliary electrode 24 are arranged in a region where the individual electrode 21 of the piezoelectric actuator 3 is formed. Also in the second modification, a plurality of recesses 12 may be communicated with each other through the connection grooves 13 as in the present embodiment.

  In the third modified embodiment, as shown in FIG. 8, the individual electrode 22 and the common electrode 23 are arranged in a region where they do not overlap when viewed from the thickness direction of the piezoelectric actuator 3. In this case, the region between the individual electrode 22 and the common electrode 23 as viewed from the thickness direction of the piezoelectric actuator 3 of the piezoelectric sheet 25 is polarized in the thickness direction, and this embodiment and the first and second modifications Unlike the form, the electric field direction from the individual electrode 22 toward the common electrode 23 and the polarization direction of the piezoelectric sheet 25 are not parallel. The piezoelectric actuator 3 is arranged in a region where the first surface electrode 20 overlaps the individual electrode 22 as viewed from the thickness direction of the piezoelectric actuator 3, and the second surface electrode 21 is arranged in a region where the common electrode 23 overlaps. For this reason, the thickness of the region in the piezoelectric actuator 3 is increased.

  In any of the variations, as in the present embodiment, the recess 12 is formed at a position facing the second surface electrode 21 on the surface of the flow path unit 2 that contacts the piezoelectric actuator 3. Therefore, when the piezoelectric actuator 3 is pressed, the region where the second surface electrode 21 is disposed is also deformed to the flow path unit 2 side in the same manner as the region where the first surface electrode 20 is disposed. It is possible to suppress the pressing force from being concentrated on the region where the surface electrode 21 is disposed. The recess 12 also functions as an adhesive relief groove when the flow path unit 2 and the piezoelectric actuator 3 are joined with an adhesive.

  Further, in the present embodiment and the first and second modifications, the common electrode 23 is formed on the surface of the piezoelectric actuator 3 that contacts the flow path unit 2. In order to separate the ink and the piezoelectric sheet 25, an ink separation film made of a metal material or a resin material may be formed. Furthermore, in the third modification, an ink isolation film may be formed on the surface of the piezoelectric actuator 3 that contacts the flow path unit 2. The ink separation film may be bonded to the piezoelectric actuator 3 first, and then the piezoelectric actuator 3 and the flow path unit 2 may be bonded. Alternatively, the ink separation film may be bonded to the flow path unit 2 first, and then the piezoelectric actuator 3 and the flow path. The road unit 2 may be joined.

  Further, in the present embodiment, and in the first and second modifications, the piezoelectric actuator 3 includes the region where the first surface electrode 20 and the individual electrode 22 are disposed, the second surface electrode 21 and the auxiliary electrode 24. However, the thickness of the regions is not limited to this, and the thicknesses of these regions may be different. In this case, if the thickness of the region where the second surface electrode 21 and the auxiliary electrode 24 of the piezoelectric actuator 3 are disposed is thicker than the region where neither the first surface electrode 20 nor the individual electrode 22 is disposed, the present invention. Can be applied.

  Furthermore, the auxiliary electrode 24 is not necessarily arranged in the region where the second surface electrode 21 is arranged, and the auxiliary electrode 24 may not be arranged. Even in this case, if the thickness of the region where the second surface electrode 21 of the piezoelectric actuator 3 is disposed is thicker than the region where neither the first surface electrode 20 nor the individual electrode 22 is disposed, the present invention is applied. be able to.

  In the above description, the flow path unit 2 is formed by laminating metal plates, but is not limited thereto, and may be formed by a resin plate or the like. Furthermore, a part of the plates constituting the flow path unit 2 (for example, only the nozzle plate 9) may be formed of a resin plate. Further, the flow path unit 2 may be formed of a silicon substrate or the like.

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Flow path unit 3 Piezoelectric actuator 4 Flexible cable 10 Pressure chamber 12 Recess 13 Connection groove 20 First surface electrode 21 Second surface electrode 22 Individual electrode 23 Common electrode 24 Auxiliary electrode 25 Piezoelectric sheet

Claims (7)

A nozzle and a flow path unit having a pressure chamber communicating with the nozzle;
In a liquid ejection apparatus including a piezoelectric actuator that covers the pressure chamber and is joined to the flow path unit,
The piezoelectric actuator is formed by laminating a piezoelectric sheet and a plurality of types of electrodes, and at least one of the plurality of types of electrodes is disposed in a partial region of the piezoelectric sheet. The piezoelectric actuator has regions having different thicknesses in the surface direction of the piezoelectric actuator,
The liquid ejecting apparatus according to claim 1, wherein the pressure chamber or the recess is formed in a region of the flow path unit facing a region where the piezoelectric actuator is thick.   The pressure chamber and the recess are formed on a surface of the flow path unit that contacts the piezoelectric actuator, and a cross-sectional area of the recess on a surface orthogonal to the surface is smaller than a cross-sectional area of the pressure chamber. The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is a liquid ejection device. The piezoelectric actuator is formed by laminating a piezoelectric sheet, individual electrodes, and a common electrode, a first surface electrode connected to the individual electrode on a surface of the piezoelectric actuator, and a second surface electrode connected to the common electrode Have
The pressure chamber is formed in a region facing the first surface electrode of the flow channel unit, and the concave portion is formed in a region facing the second surface electrode of the flow channel unit. The liquid ejection apparatus according to claim 1 or 2. A plurality of the concave portions facing the second surface electrode and the second surface electrode, respectively,
The liquid ejection apparatus according to claim 3, wherein a connection groove that communicates the plurality of recesses with each other is formed on a surface of the flow path unit that contacts the piezoelectric actuator. The second surface electrode is disposed in a region on the outer peripheral side of a region where the individual electrode is disposed on a surface opposite to a surface of the piezoelectric actuator that is in contact with the flow path unit.
The recess is formed across a region where the piezoelectric actuator contacts and a region outside the region on the surface of the flow path unit that contacts the piezoelectric actuator,
5. The liquid ejection device according to claim 4, wherein the connection groove is formed in a region outside the region where the piezoelectric actuator abuts on a surface of the flow path unit that abuts on the piezoelectric actuator. In the region where the second surface electrode of the piezoelectric actuator is disposed, a plurality of the piezoelectric sheets are laminated between the common electrode and the second surface electrode, and a through hole is formed in each of the plurality of piezoelectric sheets. And
The second surface electrode is electrically connected to the common electrode by a conductive material filled in the through hole,
6. The liquid ejection apparatus according to claim 3, wherein auxiliary electrodes are formed between the piezoelectric sheets of the plurality of piezoelectric sheets so that the through holes are electrically connected to each other.   The liquid ejecting apparatus according to claim 6, wherein the auxiliary electrode is formed over the entire outer peripheral region of the piezoelectric actuator.

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