JP6633852B2 - Piezoelectric element and inkjet head - Google Patents

Description

This specification discloses a piezoelectric film, a piezoelectric element having the piezoelectric film, and an inkjet head having the piezoelectric element. The piezoelectric element can be a piezoelectric actuator or a piezoelectric sensor.

  An example of an ink jet head having a piezoelectric element is disclosed in Japanese Patent Application Laid-Open No. H11-163,837. The inkjet head of Patent Document 1 includes a silicon substrate in which a cavity (pressure chamber) as an ink reservoir is formed, a vibration film forming a top wall of the cavity, and a piezoelectric element arranged on the surface of the vibration film. The piezoelectric element includes a lower electrode, an upper electrode, and a piezoelectric film sandwiched therebetween. When a driving voltage is applied between the upper electrode and the lower electrode, the piezoelectric film is deformed by the inverse piezoelectric effect, and accordingly, the vibrating film is deformed together with the piezoelectric element. The deformation of the vibrating membrane causes a change in the volume of the cavity, whereby the ink in the cavity is pressurized and ejected.

The lower electrode, the upper electrode, and the piezoelectric film are each formed in a substantially rectangular shape on the cavity, and are formed so as to have a substantially uniform film thickness. As the piezoelectric film, a PZT (lead zirconate titanate) film formed by a sol-gel method or a sputtering method is used.
In the cut surface crossing the cavity, the side wall of the cavity and the lower surface of the vibrating membrane each present a straight line, and the straight lines form an angle. That is, the side wall of the cavity and the lower surface of the vibrating membrane are flat surfaces, and a corner is formed where they intersect.

JP 2013-215930 A

One embodiment of the present invention provides a piezoelectric film having excellent orientation and withstand voltage.
One embodiment of the present invention provides a piezoelectric element having a piezoelectric film having excellent orientation and withstand voltage.
One embodiment of the present invention provides an ink jet head including a piezoelectric element having a piezoelectric film having excellent orientation and pressure resistance.

One embodiment of the present invention provides a piezoelectric film including a columnar tissue layer and an amorphous tissue layer of a piezoelectric material laminated in contact with the columnar tissue layer.
The columnar texture layer has a uniform crystal orientation. The amorphous structure layer has a dense film quality and excellent pressure resistance. Since the amorphous structure layer is laminated in contact with the columnar structure layer, it follows the orientation of the columnar structure layer. Therefore, the piezoelectric film in which the columnar texture layer and the amorphous texture layer are stacked has excellent orientation and pressure resistance.

  In one embodiment of the present invention, the columnar tissue layer has a <100> orientation or a <111> orientation. When the columnar texture layer has a <100> orientation, the amorphous texture layer also has a strong tendency to the orientation. In this case, the piezoelectric film has such a property that displacement due to the inverse piezoelectric effect upon application of a voltage is large and electromotive force due to the piezoelectric effect upon deformation is large. On the other hand, when the columnar texture layer has the <111> orientation, the amorphous texture layer also has a strong tendency to the orientation. In this case, the piezoelectric film has a property that the magnitude of displacement due to the piezoelectric effect when applying a voltage is easily controlled, and that the electromotive force due to the piezoelectric effect during deformation is stable.

The columnar tissue layer can be formed by, for example, a sputtering method, and thereby, a columnar tissue layer having high orientation controllability can be formed.
In one embodiment of the present invention, the columnar tissue layer is a layer formed by depositing a piezoelectric material in a polarized state. By forming the piezoelectric material in a polarized state, a columnar tissue layer having high orientation controllability can be formed. More specifically, a columnar tissue layer can be formed by depositing a piezoelectric material by a sputtering method in a state where an electric field is applied.

The amorphous structure layer can be formed by, for example, a sol-gel method, whereby a dense and high withstand pressure amorphous structure layer can be formed.
In one embodiment of the present invention, the columnar texture layer and the amorphous texture layer are layers of the same type of piezoelectric material. By forming the columnar structure layer and the amorphous structure layer with the same type of piezoelectric material, the orientation of the amorphous structure layer can be more strictly controlled, thereby providing a piezoelectric film having excellent orientation and pressure resistance. it can.

One embodiment of the present invention includes a lower electrode, a piezoelectric film provided on the lower electrode and having the above-described characteristics, and a lower film provided on the piezoelectric film and sandwiching the piezoelectric film. A piezoelectric element is provided that includes an upper electrode facing the electrode.
With this configuration, it is possible to provide a piezoelectric element having a configuration in which a piezoelectric film having excellent orientation and withstand voltage is sandwiched between an upper electrode and a lower electrode. By applying a drive voltage between the upper electrode and the lower electrode, the piezoelectric film can be deformed by the inverse piezoelectric effect. Further, by deforming the piezoelectric film by an external force, a voltage can be generated between the upper electrode and the lower electrode by the piezoelectric effect. By controlling the orientation of the columnar tissue layer according to the required characteristics, a piezoelectric actuator or a piezoelectric sensor having excellent characteristics can be realized. For example, when the columnar tissue layer has a <100> orientation, the piezoelectric film has a property that displacement due to the inverse piezoelectric effect when voltage is applied is large and electromotive force due to the piezoelectric effect when deformed is large. Therefore, a piezoelectric actuator having excellent driving performance and a piezoelectric sensor having high sensitivity can be realized. Further, when the columnar tissue layer has the <111> orientation, the piezoelectric film has a property that the magnitude of displacement due to the piezoelectric effect at the time of applying a voltage is easily controlled and the electromotive force at the time of deformation is stabilized. . Therefore, a piezoelectric actuator with excellent controllability and a piezoelectric sensor with stable output can be realized.
In one embodiment of the present invention, the piezoelectric film or the upper electrode includes a starting point of displacement of the piezoelectric film.

In one embodiment of the present invention, a substrate that partitions a cavity in which ink is stored, a vibration film that is supported by the substrate and partitions the cavity, and that is disposed on the vibration film and displaces the vibration film And a piezoelectric element that changes the volume of the cavity by using the above-described piezoelectric element.
With this configuration, it is possible to provide an ink jet head driven by a piezoelectric element having a piezoelectric film having excellent orientation and withstand voltage. By controlling the orientation of the columnar structure layer according to the required characteristics, an ink jet head having excellent characteristics can be realized. For example, when the columnar tissue layer has a <100> orientation, the displacement of the piezoelectric film due to the inverse piezoelectric effect when a voltage is applied is large. Therefore, an ink jet head having excellent driving performance can be provided. In addition, when the columnar tissue layer has the <111> orientation, the magnitude of displacement of the piezoelectric film due to the piezoelectric effect when a voltage is applied is easily controlled. Therefore, an inkjet head having excellent controllability can be provided.

FIG. 1 is an illustrative sectional view for explaining a configuration of an ink jet head according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view (a cross-sectional view taken along the line II-II in FIG. 3) illustrating a configuration of a main part of the inkjet head. FIG. 3 is a schematic plan view of the inkjet head. FIG. 4 is a schematic enlarged sectional view taken along line IV-IV in FIG. FIG. 5 is a schematic perspective view of the inkjet head. FIG. 6 is an enlarged plan view illustrating a configuration example of an operation monitoring electrode provided on a piezoelectric element that drives the inkjet head. FIG. 7 is a schematic sectional view for explaining an operation state of the ink jet head. FIG. 8 is a schematic sectional view showing a configuration example of a piezoelectric film provided in the piezoelectric element. 9A and 9B are schematic plan views showing examples of patterns of a seed layer for forming a piezoelectric film. FIG. 10A to FIG. 10D show modified examples relating to the arrangement of the weights provided in the piezoelectric element. FIGS. 11A to 11I show modified examples relating to the starting point of the displacement of the piezoelectric film. FIG. 12A and FIG. 12B show a modified example relating to a feature of providing a piezoelectric element with a third electrode in addition to an upper electrode (first electrode) and a lower electrode (second electrode). FIGS. 13A to 13D are schematic sectional views showing modified examples related to the shape of the cavity provided in the inkjet head. FIG. 14A and FIG. 14B show modified examples relating to separation of the vibrating membrane for each cavity. FIG. 15A to FIG. 15C show modified examples relating to the arrangement of a drive IC for driving the piezoelectric element.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an illustrative cross-sectional view for explaining a configuration of an inkjet head 1 according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing a configuration of a main part of the inkjet head 1 in an enlarged manner.
The inkjet head 1 includes an actuator substrate 2, a nozzle substrate 3, a protection substrate 4, and a driving IC 5.

  The actuator substrate 2 is made of, for example, a silicon substrate and partitions a plurality of cavities 6. The plurality of cavities 6 are arranged, for example, in a direction perpendicular to each paper surface of FIGS. 1 and 2. The actuator substrate 2 supports the vibration film 10 on the surface 2a. The vibration film 10 forms the top wall of the cavity 6 and partitions the cavity 6. The piezoelectric element 20 is arranged on the vibration film 10.

  The nozzle substrate 3 is joined to the back surface 2b of the actuator substrate 2. The nozzle substrate 3 is made of, for example, a silicon substrate, is adhered to the back surface 2 b of the actuator substrate 2, and defines a cavity 6 together with the actuator substrate 2 and the vibration film 10. The nozzle substrate 3 has a concave portion 33 facing the cavity 6, and the ink discharge passage 31 is formed on the bottom surface of the concave portion 33. The ink discharge passage 31 penetrates the nozzle substrate 3 and has a discharge port 32 on the side opposite to the cavity 6. Therefore, when the volume of the cavity 6 changes, the ink stored in the cavity 6 is discharged from the discharge port 32 through the ink discharge passage 31.

  The protection substrate 4 is made of, for example, a silicon substrate. The protection substrate 4 is arranged so as to cover the piezoelectric element 20, and is joined to the front surface 2 a of the actuator substrate 2. The protection substrate 4 has a housing recess 42 on a facing surface 41 facing the surface 2 a of the actuator substrate 2. The plurality of piezoelectric elements 20 respectively corresponding to the plurality of cavities 6 are accommodated in the accommodation recess 42.

The drive IC 5 is mounted on the front surface 2a of the actuator substrate 2. The wiring 15 for connecting the piezoelectric element 20 and the driving IC 5 is formed on the actuator substrate 2. The wiring 15 is drawn out of the protection substrate 4. The drive IC 5 is bonded onto the land 16 of the wiring 15, whereby the drive IC 5 is mounted on the actuator substrate 2.
The drive IC 5 is a semiconductor integrated circuit, and may have, for example, a form of a chip size package. The drive IC 5 specifically includes a semiconductor substrate 51, an active region 52 disposed on the front surface 51a side of the semiconductor substrate 51, and a bump 53 serving as an output terminal disposed on the back surface 51b of the semiconductor substrate 51. Transistors and other semiconductor devices are formed in the active region 52. A protective resin layer 54 and the like are arranged on the surface of the semiconductor substrate 51 so as to protect the active region 52. A through via 55 is formed in the semiconductor substrate 51. The through via 55 may be made of a through-silicon via (TSV). The through via 55 connects the active region 52 and the bump 53, and leads an output terminal of an electronic circuit formed in the active region 52 to the back surface 51 b of the semiconductor substrate 51. The back surface 51b of the semiconductor substrate 51 is the first surface 5a of the drive IC 5. The first surface 5a faces the actuator substrate 2, and a plurality of bumps 53 constituting output terminals of the driving IC 5 are arranged in a concentrated manner. The number of the bumps 53 substantially corresponds to the number of the piezoelectric elements 20 provided on the actuator substrate 2. For example, if about 300 piezoelectric elements 20 are provided on the actuator substrate 2, the number of the bumps 53 as output terminals is about 300. These bumps 53 are joined on the lands 16 of the wiring 15 corresponding to the plurality of piezoelectric elements 20. As a result, the electrical connection between the drive IC 5 and the piezoelectric element 20 is achieved without using wire bonding or FPC (flexible printed circuit board).

  On the second surface 5b of the drive IC 5 located on the active region 52 side of the semiconductor substrate 51, input terminals 56 connected to the active region 52 are arranged in a concentrated manner. The input terminal 56 may have a form of a pad exposed from the protective resin layer 54. On the other hand, one end of the FPC 57 is fixed to the actuator substrate 2 near the drive IC 5. A plurality of input terminals 56 are connected to a plurality of core wires of the FPC 57 via bonding wires 58, respectively. The number of input terminals 56 is, for example, about 20, and accordingly, the number of core wires of FPC 57 is also about 20. The FPC 57 is connected to, for example, a control IC (not shown).

  An ink tank 8 storing ink is disposed on the protection substrate 4. An ink supply path 43 is formed so as to penetrate the protection substrate 4. The ink supply port 8 a of the ink tank 8 is connected to the ink supply path 43. The ink supply path 43 of the protection substrate 4 communicates with an ink supply path 44 in the actuator substrate 2. The ink supply path 44 communicates with the cavity 6. Therefore, the ink in the ink tank 8 as the ink supply source is supplied to the cavity 6 through the ink supply paths 43 and 44.

FIG. 3 is a schematic plan view of the inkjet head 1 (particularly, the actuator substrate 2). FIG. 4 is a schematic enlarged sectional view taken along line IV-IV in FIG. FIG. 5 is a schematic perspective view of the inkjet head 1 (particularly, the actuator substrate 2). FIG. 2 is a cross-sectional view taken along the line II-II of FIG.
The vibration film forming layer 11 is formed on the surface 2a of the actuator substrate 2. In the vibration film forming layer 11, the portion constituting the bottom wall of the cavity 6, that is, the portion defining the cavity 6 is the vibration film 10.

  The cavity 6 is formed through the actuator substrate 2 in this embodiment. The actuator substrate 2 is further provided with an ink passage 50 communicating with the cavity 6. The ink passage 50 communicates with the cavity 6 and is formed so as to guide the ink supplied from the ink tank 8 via the ink supply path 43 of the protection substrate 4 and the ink supply path 44 of the actuator substrate to the cavity 6. I have. The ink introduced into the cavity 6 from the ink passage 50 moves along the ink flow direction 45 parallel to the longitudinal direction of the cavity 6 and reaches the ink discharge passage 31.

  In the actuator substrate 2, a plurality of cavities 6 extend in parallel with each other and are formed in a stripe shape. The plurality of cavities 6 are formed at equal intervals with a minute interval (for example, about 30 μm to 350 μm) in their width direction. Each of the cavities 6 has a rectangular shape elongated in the ink flowing direction 45 from the ink passage 50 to the ink discharge passage 31 in a plan view. The top surface of the cavity 6 has two side edges 6 a and 6 b along the ink flow direction 45 and two end edges 6 c and 6 d along a direction orthogonal to the ink flow direction 45. The ink passage 50 is formed at one end of the cavity 6 so as to be divided into two passages, and communicates with the common ink passage 49. The common ink passage 49 communicates with an ink passage 50 corresponding to the plurality of cavities 6. The ink supply path 44 through which the ink from the ink tank 8 is guided communicates with a common ink path 49. As shown in FIGS. 3 and 5, a plurality of ink supply paths 44 are arranged at intervals along a common ink path 49. The ink supply path 44 is formed so as to penetrate the vibration film 10 (further, the wiring 15 where the wiring 15 is arranged) and further penetrate the actuator substrate 2 to the common ink passage 49.

  Each cavity 6 is defined by the vibration film 10, the actuator substrate 2, and the nozzle substrate 3, and in this embodiment, is formed in a substantially rectangular parallelepiped shape. The length of the cavity 6 may be, for example, about 800 μm and its width may be about 55 μm. The ink passage 50 is formed so as to communicate with one end in the longitudinal direction of the cavity 6 (in this embodiment, an end located on the side opposite to the ejection port 32). In this embodiment, the discharge port 32 of the nozzle substrate 3 is arranged near the other end of the cavity 6 in the longitudinal direction.

  The vibration film 10 may be a single film of a silicon oxide film or a stacked film in which a silicon nitride film is stacked on a silicon oxide film. The cavity 6 does not need to penetrate the actuator substrate 2 and may be a recess dug from the lower surface side so as to leave a part on the piezoelectric element 20 side. In this case, the rest of the actuator substrate 2 forms a part of the vibration film 10. In this specification, the vibration film 10 means a top wall portion of the vibration film forming layer 11 that partitions the cavity 6.

  Vibrating film 10 has a thickness of, for example, 0.4 μm to 2 μm. When the vibration film 10 is made of a silicon oxide film, the thickness of the silicon oxide film may be about 1.2 μm. When the vibration film 10 is composed of a laminate of a silicon layer, a silicon oxide layer, and a silicon nitride layer, the thickness of each of the silicon layer, the silicon oxide layer, and the silicon nitride layer is about 0.4 μm. Is also good.

  The piezoelectric element 20 is arranged on the vibration film 10. The vibration film 10 and the piezoelectric element 20 constitute a piezoelectric actuator (an example of a piezoelectric device). The piezoelectric element 20 includes a lower electrode 22 formed on the vibration film forming layer 11, a piezoelectric film 24 formed on the lower electrode 22, and an upper electrode 21 formed on the piezoelectric film 24. I have. In other words, the piezoelectric element 20 is configured by sandwiching the piezoelectric film 24 between the upper electrode 21 and the lower electrode 22.

  The lower electrode 22 may have, for example, a two-layer structure in which a Ti (titanium) layer and a Pt (platinum) layer are sequentially stacked from the vibration film 10 side. In addition, the lower electrode 22 can be formed of a single film such as an Au (gold) film, a Cr (chromium) layer, and a Ni (nickel) layer. The lower electrode 22 has a main electrode portion 22A in contact with the lower surface of the piezoelectric film 24, and an extension 22B (see FIG. 4) extending to a region outside the piezoelectric film 24.

The piezoelectric film 24, for example, _PZT formed by a sol-gel method or a sputtering method _{(PbZr x Ti 1-x O} 3: lead zirconate titanate) can be applied membrane. Such a piezoelectric film 24 is formed of a sintered body of a metal oxide crystal. The thickness of the piezoelectric film 24 is preferably 1 μm to 5 μm. It is preferable that the entire thickness of the vibration film 10 be approximately the same as the thickness of the piezoelectric film 24 or approximately ／ of the thickness of the piezoelectric film 24.

The upper electrode 21 is formed in substantially the same shape as the piezoelectric film 24 in plan view. The upper electrode 21 may have a stacked structure in which, for example, a conductive oxide film (for example, IrO ₂ (iridium oxide) film) and a metal film (for example, Ir (iridium) film) are stacked.
The surface of the vibration film forming layer 11, the surface of the piezoelectric element 20, and the surface of the extension 22B of the lower electrode 22 are covered with the hydrogen barrier film 12. The hydrogen barrier film 12 is made of, for example, Al ₂ O ₃ (alumina). As a result, characteristic deterioration of the piezoelectric film 24 due to hydrogen reduction can be prevented. An insulating film 13 is stacked on the hydrogen barrier film 12. The insulating film 13 is made of, for example, SiO ₂ . The wiring 15 is formed on the insulating film 13. The wiring 15 may be made of a metal material containing Al (aluminum).

  One end of the wiring 15 is disposed above one end of the upper electrode 21. Between the wiring 15 and the upper electrode 21, a through-hole (contact hole) 14 that continuously penetrates the hydrogen barrier film 12 and the insulating film 13 is formed. One end of the wiring 15 enters the through hole 14 and is connected to the upper electrode 21 in the through hole 14. One end of the wiring 15 is connected to one end of the upper electrode 21 (the end on one edge side of the piezoelectric element 20), and extends in the direction opposite to the ink circulation direction in a plan view and is drawn out. The land 16 is disposed at the tip of the wiring 15 and is integrated with the wiring 15. An opening 17 (see FIG. 2) is formed in the hydrogen barrier film 12 and the insulating film 13 in a region corresponding to a central portion of the surface of the upper electrode 21 (a portion surrounded by a peripheral portion on the surface of the upper electrode 21). I have. The opening 17 is a rectangle that is long in the longitudinal direction of the upper electrode 21.

  As shown in FIG. 2, the extension 22 </ b> B of the lower electrode 22 is routed on the actuator substrate 2 and reaches the mounting area of the drive IC 5. In this mounting area, a land 22C for connecting the lower electrode 22 to the outside is arranged. The bumps 53 of the drive IC 5 are joined to the lands 22C. Thus, the connection between the lower electrode 22 and the driving IC 5 is achieved.

  The piezoelectric element 20 is formed at a position facing the cavity 6 with the vibration film 10 interposed therebetween. That is, the piezoelectric element 20 is formed so as to be in contact with the surface of the vibration film 10 on the side opposite to the cavity 6. A vibration film forming layer 11 is formed on the actuator substrate 2, and the vibration film 10 is supported by a portion around the cavity 6 in the vibration film forming layer 11. Thus, the vibration film 10 is supported by the actuator substrate 2. The vibrating film 10 has flexibility that can be deformed in a direction facing the cavity 6 (in other words, a thickness direction of the vibrating film 10).

  The driving IC 5 is connected to the respective upper electrodes 21 of the plurality of piezoelectric elements 20 via the bumps 53 and the wirings 15, and is connected to the lower electrode 22 common to the plurality of piezoelectric elements 20 via another bump 53. ing. Thus, the drive IC 5 can apply a drive voltage between the upper electrode 21 and the lower electrode 22 of each piezoelectric element 20. When a drive voltage is applied from the drive IC 5 to the piezoelectric element 20, the piezoelectric film 24 is deformed by the inverse piezoelectric effect. As a result, the vibration film 10 is deformed together with the piezoelectric element 20, whereby the volume of the cavity 6 is changed, and the ink in the cavity 6 is pressurized. The pressurized ink is discharged as fine droplets from the discharge port 32 through the ink discharge passage 31.

  The length of the piezoelectric element 20 in the ink flow direction 45 (the same direction as the longitudinal direction of the vibration film 10) is shorter than the length of the vibration film 10 in the longitudinal direction, and has a rectangular shape in plan view. . Then, as shown in FIG. 3, both ends 20 d and 20 c in the longitudinal direction of the piezoelectric element 20 are aligned with corresponding ends (corresponding to both ends 6 c and 6 d of the cavity 6 in plan view) of the vibration film 10. They are arranged inside at a predetermined interval d1 (for example, 5 μm). The width of the piezoelectric element 20 in the short direction perpendicular to the longitudinal direction of the vibration film 10 (the direction parallel to the main surface of the actuator substrate 2) is the width of the vibration film 10 (the top surface of the cavity 6). Is formed to be narrower than the width. Then, both side edges 20a and 20b along the longitudinal direction of the piezoelectric element 20 are spaced apart from the corresponding side edges of the vibrating membrane 10 by a predetermined distance d2 (for example, coincide with the side edges 6a and 6b of the cavity 6 in a plan view). (5 μm).

  As shown in FIG. 3, the lower electrode 22 has a predetermined width in the ink circulation direction 45 in a plan view and extends across the plurality of cavities 6 in a direction orthogonal to the ink circulation direction 45. This is a common electrode shared by the piezoelectric elements 20. The first side 22a of the lower electrode 22 along a direction orthogonal to the ink circulation direction 45 is aligned with a line connecting one end of the plurality of piezoelectric elements 20 in a plan view. The second side 22b of the lower electrode 22 facing the first side 22a is located outside the edge 6d (the edge of the vibration film 10) of the cavity 6 corresponding to the other edge of the plurality of piezoelectric elements 20 (the edge thereof). (Downstream side in the ink circulation direction 45).

  The lower electrode 22 is drawn out in a direction along the surface of the vibrating film forming layer 11 from the main electrode portion 22A, which is a rectangular shape in a plan view, constituting the piezoelectric element 20 and the main electrode portion 22A. ) And an extension 22 </ b> B extending outward from the periphery of the top surface of the cavity 6. The shape, size, and arrangement of the main electrode portion 22A in plan view are the same as those of the piezoelectric element 20.

  The extension portion 22B extends outward from the side edge of the top surface portion of the cavity 6 across each side edge of the main electrode portion 22A from the corresponding side edge of the top surface portion of the cavity 6 in plan view. The extension portion 22B is a region excluding the main electrode portion 22A in the entire region of the lower electrode 22. On the extension portion 22B, a rectangular cutout portion 22D in a plan view penetrating the lower electrode 22 is formed on the downstream side of each piezoelectric element 20 in the ink circulation direction 45. Each cutout 22D has two side edges (short sides) along the ink circulation direction 45 and two edges (long sides) along a direction orthogonal to the ink circulation direction in plan view. One edge of the cutout portion 22D is arranged at a position matching the edge of the piezoelectric element 20 (the edge on the downstream side of the main electrode portion 22A) in the ink flowing direction, and the other edge is the edge of the vibration film 10. Outside (downstream side in the ink flow direction 45). One side edge of the cutout portion 22D is disposed outside one side edge of the diaphragm 10, and the other side edge of the cutout portion 22D is disposed outside the other side edge of the diaphragm 10. Therefore, in plan view, the end on the edge side of the diaphragm 10 is disposed inside the cutout 22D.

The upper electrode 21 is formed in a rectangular shape in the same pattern as the main electrode portion 22A of the lower electrode 22 in plan view. That is, the shape, size, and arrangement of the upper electrode 21 in plan view are the same as those of the piezoelectric element 20.
The piezoelectric film 24 is formed in a rectangular shape having the same pattern as the upper electrode 21, that is, the same pattern as the piezoelectric element 20 in a plan view. The lower surface of the piezoelectric film 24 is in contact with the upper surface of the main electrode portion 22A of the lower electrode 22, and the upper surface of the piezoelectric film 24 is in contact with the lower surface of the upper electrode 21.

  In the extension 22B of the lower electrode 22, a separation groove 60 is formed between the adjacent cavities 6. In this embodiment, the separation groove 60 extends linearly along the longitudinal direction of the cavity 6, and separates the lower electrode 22 into a portion corresponding to each cavity 6. In this embodiment, both ends of the separation groove 60 are located outside the both ends of the cavity 6 in the longitudinal direction. Therefore, the separation groove 60 is formed over a range from one end to the other end of the partition wall 61 (see FIG. 4) that partitions the adjacent cavity 6. As shown in FIG. 4, the separation groove 60 penetrates through the lower electrode 22 and the vibration film 10 and reaches a partition wall 61 that partitions between adjacent cavities 6. The portion formed in the partition wall 61 of the separation groove 60 has a depth exceeding one half of the height of the partition wall 61 (equal to the height of the cavity 6).

  As described above, the separation groove 60 separates the vibration film 10 and the lower electrode 22 corresponding to the adjacent cavities 6 from each other. Thereby, the vibration film 10 of each cavity 6 can be displaced independently from the vibration film 10 of the adjacent cavity 6. Further, since the separation groove 60 is formed at a depth reaching the partition wall 61 between the adjacent cavities 6, the partition wall 61 can be displaced with the displacement of the diaphragm 10.

  As shown in FIG. 4, the piezoelectric film 24 has a thick film portion 25 at a central portion in the transverse direction and a thin film portion 26 at both side portions in the transverse direction in a transverse cross section along the transverse direction. . The thick film portion 25 and the thin film portion 26 each extend in a straight band along the longitudinal direction of the cavity 6. The width of the thick film portion 25 is, for example, half or less of the length of the cavity 6 in the short direction. As shown in FIGS. 2 and 3, in the thick film portion 25, the length of the cavity 6 in the longitudinal direction is shorter than the length of the piezoelectric film 24 in the same direction. The thin film portions 26 are formed at both ends of the piezoelectric film 24. That is, the thin film portion 26 is formed in a band shape along the periphery of the piezoelectric film 24 so as to surround the thick film portion 25 in a ring shape. The thick film portion 25 functions as a weight that contributes to an increase in inertial mass near the center of the movable portion including the piezoelectric element 20 and the vibrating film 10. The upper electrode 21 is in contact with the thick film portion 25 and the thin film portion 26.

  At the boundary between the thick film portion 25 and the thin film portion 26, a step surface 28 (see FIGS. 2 and 4) corresponding to the difference in film thickness between the thick film portion 25 and the thin film portion 26 is formed. The surface of the thick film portion 25 and the step surface 28 intersect at a substantially right angle, whereby a bent portion 27 is formed. As described above, since the thin film portion 26 is formed in a ring shape, the bent portion 27 is also formed in a ring shape. That is, the bent portion 27 has both sides extending along the longitudinal direction of the cavity 6, and both ends connecting the both sides at both ends in the longitudinal direction of the cavity 6. The bent portion 27 functions as a starting point at which the displacement starts when a driving voltage is applied between the upper electrode 21 and the lower electrode 22 and the vibration film 10 is displaced together with the piezoelectric element 20.

  As shown in FIGS. 2 and 4, the inner wall surface 62 of the cavity 6 has a curved surface portion 62 </ b> A at a position in contact with the vibration film 10. It is preferable that the curved surface portion 62A extends over the entire periphery of the peripheral edge where the diaphragm 10 and the inner wall surface 62 are in contact. The curved surface portion 62A is in contact with the vibration film 10 at the upper edge thereof, and is connected to the flat surface portion 62B at the lower edge thereof. The curved surface portion 62 </ b> A forms a concave curved surface that recedes from the edge in contact with the vibration film 10 toward the outside of the cavity 6 and toward the nozzle substrate 3. The flat surface portion 62B is a part of the inner wall surface 62 of the cavity 6. The lower edge of the flat surface portion 62 </ b> B is in contact with the nozzle substrate 3. The flat surface portion 62B may be along the normal direction of the vibration film 10 or may be inclined with respect to the normal direction of the vibration film 10. For example, it is preferable that the flat surface portion 62B is inclined toward the outside of the cavity 6 and the nozzle substrate 3 with respect to the normal direction of the vibration film 10 from the edge portion continuous with the curved surface portion 62A.

  As shown in an enlarged plan view in FIG. 6, the upper electrode 21 is formed with a notch portion 35 which is hollowed inward from the periphery. In this embodiment, the notch 35 is disposed at one corner of the upper electrode 21, and extends linearly by a predetermined length from one end of the upper electrode 21 along the longitudinal direction of the cavity 6. The operation monitoring electrode 23 is arranged in the notch portion 35. The operation monitoring electrode 23 is in contact with the upper surface of the piezoelectric film 24. The operation monitoring electrode 23 is arranged in a region (in the notch 35) overlapping the cavity 6 in plan view. Therefore, the operation monitoring electrode 23 is opposed to the main electrode portion 22A of the lower electrode 22 with the piezoelectric film 24 interposed therebetween. The operation monitoring electrode 23 is formed in a U-shape in the notch portion 35. At both ends of the operation monitoring electrode 23, a pair of terminals 23a and 23b are provided. The pair of terminal portions 23 a and 23 b are outside the notch portion 35. In this embodiment, the pair of terminal portions 23 a and 23 b are arranged on the actuator substrate 2 in a region outside the cavity 6, more specifically, in a region outside the protection substrate 4.

  The pair of terminals 23a and 23b are connected to a drive state monitoring circuit 36. The driving state monitoring circuit 36 includes a temperature detection circuit that measures the electric resistance between the terminal portions 23a and 23b, that is, the electric resistance of the operation monitoring electrode 23, and thereby detects the temperature of the piezoelectric film 24. When the piezoelectric film 24 expands and contracts due to the inverse piezoelectric effect, the temperature of the piezoelectric film 24 increases accordingly. The driving state monitoring circuit 36 detects the operating state of the piezoelectric element 20 by measuring the temperature of the piezoelectric film 24. If the temperature rise of the piezoelectric film 24 is not detected even though the driving voltage is applied to the piezoelectric element 20, there is a possibility that the piezoelectric element 20 is abnormal. As described above, in this embodiment, the operation monitoring electrode 23 is a temperature detection electrode used to detect the temperature of the piezoelectric film 24.

  The drive IC 5 applies a drive voltage between the upper electrode 21 and the lower electrode 22 to drive the piezoelectric element 20. Thereby, the piezoelectric film 24 is deformed by the inverse piezoelectric effect, and the vibration film 10 is displaced accordingly. As a result, the volume of the cavity 6 changes and the pressure inside the cavity 6 increases, so that ink droplets are ejected from the ejection ports 32 formed in the nozzle substrate 3. On the other hand, ink from the ink tank 8 is supplied to the cavity 6 through the ink supply paths 43 and 44, the common ink path 49, and the ink path 50.

  In this embodiment, the piezoelectric film 24 has a thick film portion 25 arranged near the center of the vibration film 10. The thick film portion 25 has a function as a weight that locally increases the inertial mass near the center of the vibration film 10. The thick film portion 25 as a weight amplifies the displacement of the vibration film 10 by its inertial mass when the driving voltage is applied and the vibration film 10 is displaced. Thereby, the volume of the cavity 6 can be largely changed, so that the inkjet head 1 having excellent driving performance can be realized.

Since the weight is configured using the thick film portion 25 of the piezoelectric film 24, the piezoelectric element 20 having the weight built therein can be configured with a simple configuration.
The thick film portion 25 as a weight extends along the longitudinal direction of the cavity 6 having a rectangular shape in a plan view, and is formed in a belt shape having a half or less of the length of the cavity 6 in the transverse direction. It is located near the center. As a result, a sufficient interval from the side edge of the cavity 6 to the edge of the thick film portion 25 is secured. Thereby, the displacement of the vibrating film 10 can be effectively increased by the inertial mass of the thick film portion 25 as a weight, so that the driving performance of the inkjet head 1 can be improved.

  In this embodiment, a bent portion 27 is formed at the boundary between the thick film portion 25 and the thin film portion 26 of the piezoelectric film 24. The bent portion 27 is a peculiar shape portion in the piezoelectric film 24, and provides a starting portion that becomes a starting point of displacement of the piezoelectric film 24. Therefore, when the piezoelectric film 24 is deformed (displaced), it can be guaranteed that the deformation (displacement) starts from the bent portion 27 as the starting point. Therefore, the deformation (displacement) of the piezoelectric film 24 similarly occurs in the plurality of piezoelectric elements 20 and the plurality of driving operations. Thereby, operation control is easy and highly accurate operation is possible. Therefore, the piezoelectric element 20 with high operation controllability can be realized, and the inkjet head 1 with high operation controllability can be provided accordingly. That is, it is possible to provide the inkjet head 1 capable of performing stable and accurate operation control.

  The bent portion 27 is formed by providing a convex portion (thick film portion 25) and a concave portion (thin film portion 26) projecting in the laminating direction of the upper electrode 21, the piezoelectric film 24 and the lower electrode 22 on the surface of the piezoelectric film 24. , Formed between them. More specifically, assuming a rectangular outline that covers the transverse section of the piezoelectric film 24, a step is interposed at an intermediate position on the upper side of the rectangular outline. Thereby, a bent portion 27 is formed as a peculiar shape point, and the bent portion 27 causes interruption of the outer contour line in the middle. Thereby, the displacement of the piezoelectric film 24 can be generated with the bent portion 27 as a starting point.

The bent portion 27 is a kind of a concave shape that is concave along the laminating direction. The bent portion 27 is a fragile portion that is fragile compared to other portions in the piezoelectric element 20. Therefore, the bent portion 27 can reliably provide a starting point of the displacement of the piezoelectric film 24.
Further, the bent portion 27 is in contact with the peripheral edge of the piezoelectric element 20 and reaches a region inside the peripheral edge of the piezoelectric element 20. Accordingly, the displacement of the piezoelectric film 24 easily starts, and the displacement of the piezoelectric film 24 easily propagates to the whole. Therefore, it is possible to provide the piezoelectric element 20 with high responsiveness, and accordingly, it is possible to realize the ink jet head 1 including the piezoelectric element 20 with high operation control.

Further, since the bent portion 27 is continuous with the peripheral edge of the piezoelectric film 24, it can be formed simultaneously when the peripheral edge of the piezoelectric film 24 is processed. Therefore, the inkjet head 1 including the piezoelectric element 20 having high operation controllability can be realized without increasing the number of manufacturing steps.
In addition, since the bending portion 27 serving as the starting point of the displacement is provided in the piezoelectric film 24, the displacement of the piezoelectric film 24 can be surely generated from the bending portion 27, thereby improving the operation controllability. The inkjet head 1 including the high piezoelectric element 20 can be realized.

Further, since the bent portion 27 has a shape extending along the peripheral edge of the piezoelectric element 20, the displacement of the piezoelectric film 24 can be reliably started in a wide range. Inkjet head 1 including the piezoelectric element 20 having a high height can be realized.
Further, since the bent portions 27 are also located near both ends in the longitudinal direction of the cavity 6, the displacement of the piezoelectric film 24 can be started from near both ends of the cavity 6. This makes it possible to provide the ink jet head 1 that is excellent not only in operation controllability but also in response to a drive voltage.

Further, since the bent portion 27 extends along the side along the longitudinal direction of the cavity 6, the displacement of the piezoelectric film 24 starts in a wide range in response to the application of the driving voltage. This makes it possible to provide the ink jet head 1 that is excellent not only in operation controllability but also in response to a drive voltage.
In this embodiment, the piezoelectric element 20 includes an operation monitoring electrode 23 as a third electrode in addition to an upper electrode 21 as a first electrode and a lower electrode 22 as a second electrode. Are in contact with the piezoelectric film 24. The state of the piezoelectric film 24 can be detected by the operation monitoring electrode 23. In this embodiment, the operation monitoring electrode 23 is a temperature detection electrode that detects the temperature of the piezoelectric film 24. That is, by applying a drive voltage from the drive IC 5 to the upper electrode 21 and the lower electrode 22 to operate the piezoelectric element 20, the temperature of the piezoelectric film 24 increases. Therefore, the operation of the piezoelectric element 20 can be confirmed by detecting the temperature of the piezoelectric film 24 by the operation monitoring electrode 23.

In this embodiment, since the operation monitoring electrode 23 is arranged on the same layer as the upper electrode 21, it can be formed in the same process as the upper electrode 21 when manufacturing the piezoelectric element 20. Therefore, it is possible to provide the inkjet head 1 including the piezoelectric element 20 having the state monitoring function without increasing the number of steps.
Further, in this embodiment, the upper electrode 21 has a notch portion 35 which is inwardly recessed from the periphery, and the operation monitoring electrode 23 is arranged so as to enter the notch portion 35. That is, the operation monitoring electrode 23 is disposed so as to enter a region where the upper electrode 21 and the piezoelectric film 24 are in contact with each other. Therefore, since the operation monitoring electrode 23 is in contact with the piezoelectric film 24 in a region where deformation for operation occurs, the state of the piezoelectric film 24 can be monitored more accurately. More specifically, the temperature in the operation region (deformation region) of the piezoelectric film 24 can be detected.

In this embodiment, the operation monitoring electrode 23 faces the lower electrode 22 with the piezoelectric film 24 interposed therebetween. Therefore, the operation monitoring electrode 23 is in contact with the piezoelectric film 24 in the operation region when the drive voltage is applied. Thereby, the state of the piezoelectric film 24 can be monitored more accurately. More specifically, the temperature in the operation region of the piezoelectric film 24 can be detected.
In this embodiment, the operation monitoring electrode 23 is arranged at a position facing the cavity 6. Therefore, it is possible to detect the state of the piezoelectric film 24 in the operation region that is deformed for ink ejection. Thereby, the state of the piezoelectric film 24 can be detected more accurately.

  In this embodiment, the operation monitoring electrode 23 has two terminal portions 23a and 23b arranged at both ends. The driving state monitoring circuit 36 detects an electric resistance between the two terminal portions 23a and 23b. The electric resistance detected by the driving state monitoring circuit 36 corresponds to the temperature of the piezoelectric film 24. That is, in this embodiment, the drive state monitoring circuit 36 includes a temperature detection circuit that detects the temperature of the piezoelectric film 24. The operating state of the piezoelectric film 24 can be monitored by detecting the temperature of the piezoelectric film 24, particularly, the temperature of the operating region. Thus, the operation state of the inkjet head 1 can be monitored.

When the piezoelectric film 24 is deformed when a drive voltage is applied between the upper electrode 21 and the lower electrode 22, an electromotive force generated by the deformation is generated between the operation monitoring electrode 23 and the lower electrode 22. Therefore, by providing a detection circuit for detecting a potential difference between the operation monitoring electrode 23 and the lower electrode 22, the operation state of the piezoelectric film 24 can be monitored.
Further, in this embodiment, the inner wall surface 62 that partitions the cavity 6 of the actuator substrate 2 has a curved surface portion 62A that is continuous with the surface of the vibration film 10 on the cavity 6 side. Therefore, even if bubbles are contained in the ink supplied from the ink tank 8, the bubbles are difficult to be captured in the cavity 6, and are quickly discharged from the ejection port 32 together with the ink before the bubble pool is formed. . Thereby, generation of air bubbles in the cavity 6 can be suppressed or prevented. As a result, the change in the volume of the cavity 6 can be suppressed or prevented from being absorbed by the shrinkage of the bubbles, so that the ink ejection amount corresponding to the drive voltage applied to the piezoelectric element 20 can be accurately realized. Thus, it is possible to provide the ink jet head 1 with improved ink discharge controllability.

  Further, in this embodiment, the curved surface portion 62 </ b> A formed on the inner wall surface 62 of the actuator substrate 2 is connected to the contact point with the vibration film 10 in a cross section that intersects the surface of the vibration film 10, and It forms a curved part toward the contact point. In other words, the curved surface portion 62 </ b> A has a shape that recedes from the position in contact with the vibration film 10 to the outside of the cavity 6. As a result, no corners are formed between the inner wall surface 62 of the actuator substrate 2 and the vibrating film 10, so that the accumulation of bubbles is less likely to occur. Thereby, it is possible to provide the ink jet head 1 with improved ink discharge controllability.

Further, in this embodiment, the inner wall surface 62 of the actuator substrate 2 has a flat surface portion 62B continuous below the curved surface portion 62A (on the nozzle substrate 3 side). Therefore, it is possible to suppress or prevent bubbles in the ink from being captured on the inner wall surface 62 of the actuator substrate 2.
Further, in this embodiment, the curved surface portion 62 </ b> A extends over the entire circumference of the boundary between the inner wall surface 62 defining the cavity 6 of the actuator substrate 2 and the vibration film 10. Thus, the accumulation of bubbles at the intersection between the inner wall surface 62 and the vibration film 10 can be more effectively suppressed or prevented, and the ink ejection control performance can be improved accordingly.

  In this embodiment, a separation groove 60 is formed between the adjacent cavities 6, and the separation groove 60 penetrates through the vibration film 10 and reaches a partition wall 61 that partitions between the adjacent cavities 6. ing. As a result, the vibration film 10 of each cavity 6 is released from the restriction with the other parts of the vibration film 10 at the separation groove 60, so that the displacement amount increases. Further, since the separation groove 60 reaches the partition wall 61, the partition wall 61 is also displaced in accordance with the displacement of the diaphragm 10. That is, as shown in FIG. 7, when the vibration film 10 is deformed so as to protrude toward the ink cavity 6, the upper end of the partition wall 61 is pulled inside the cavity 6 by the vibration film 10 and deformed. As a result, the volume of the cavity 6 greatly changes between the state before the deformation indicated by the two-dot chain line and the state after the deformation indicated by the solid line. The ink ejection amount can be increased accordingly. From another point of view, since the volume change rate of the cavity 6 can be increased, the size of the cavity 6 for realizing a constant ink discharge amount can be reduced, and the size of the inkjet head 1 can be reduced accordingly. Can be planned.

  Further, in this embodiment, the separation groove 60 is formed continuously over a range from one end to the other end of the partition wall 61 that partitions the pair of adjacent cavities 6 (see FIG. 3). That is, a continuous separation groove 60 is formed over the entire boundary between the adjacent cavities 6. Therefore, the vibration film 10 corresponding to each cavity 6 is less restricted from the surroundings. Further, a wide range of the partition wall 61 can be largely displaced with the displacement of the diaphragm 10. Thereby, it is possible to increase the ink discharge amount or to reduce the size of the inkjet head 1.

Further, in this embodiment, since the separation groove 60 penetrates through the lower electrode 22, the restraint by the lower electrode 22 is small. Accordingly, the displacement amount of the vibration film 10 is increased and the displacement amount of the partition wall 61 is also increased, so that the ink ejection amount can be increased or the inkjet head 1 can be downsized.
Further, in this embodiment, the lower end of the separation groove 60 is located at a position lower than half the height of the partition wall 61, and the depth of the separation groove 60 is smaller than half the height of the partition wall 61. Deep. Thereby, the partition wall 61 can be greatly deformed in accordance with the deformation of the diaphragm 10, and accordingly, the volume of the cavity 6 can be largely changed. Thereby, it is possible to increase the ink ejection amount or downsize the inkjet head 1.

  In this embodiment, a drive IC 5 for driving the piezoelectric element 20 is mounted on the actuator substrate 2, and a bump 53 as an output terminal of the drive IC is provided on the first surface 5 a (opposite surface) facing the actuator substrate 2. ). These bumps 53 are joined to lands 16 and 22C provided on the wiring on the actuator substrate 2. This eliminates the need for a cable (for example, FPC) or a bonding wire for connecting the actuator substrate 2 and the output terminal of the drive IC 5. Thereby, the size of the inkjet head 1 can be reduced.

The drive IC 5 for driving the inkjet head 1 generally has more output terminals than input terminals. Therefore, significant space saving can be achieved by eliminating the cable and the bonding wire connected to the output terminal.
The concentrated arrangement means that most of the output terminals (preferably, all the output terminals) of the drive IC 5 are arranged on the first surface 5a. However, this does not prevent the input terminals from being arranged on the first surface 5a.

  Further, in this embodiment, the active region 52 is arranged on the semiconductor substrate 51 of the drive IC 5 on the side opposite to the actuator substrate 2, and the active region 52 and the output terminal (bump 53) are connected to the through via 55 (TSV). ). Thus, the output terminals can be concentrated on the first surface 5a of the drive IC 5 on the actuator substrate 2 side. The drive IC 5 having the through via 55 does not need to route the wiring from the active region 52 to the non-active surface side outside the semiconductor substrate 51, so that the drive IC 5 itself can be configured to be small. This can contribute to downsizing of the inkjet head 1.

  Further, the drive IC 5 includes a plurality of input terminals 56 arranged on the second surface 5b opposite to the first surface 5a. The plurality of input terminals 56 are connected to the FPC 57 via the bonding wires 58. The FPC 57 is connected to, for example, a control IC. Since the number of the input terminals 56 of the drive IC 5 is not so large, even if the connection between the input terminals 56 and the FPC 57 is performed by wire bonding, the size of the ink jet head 1 is not so large.

FIG. 8 is a schematic sectional view illustrating a configuration example of the piezoelectric film 24. A lower electrode 22 is formed on the vibration film 10, a piezoelectric film 24 is formed on the lower electrode 22, and an upper electrode 21 is formed on the piezoelectric film 24. The lower electrode 22 is made of, for example, a Pt / Ti laminated film having a Ti film as a lower layer and a Pt film as an upper layer. The upper electrode 21 is made of, for example, an Ir / IrO ₂ laminated film having an IrO ₂ film as a lower layer and an Ir film as an upper layer.

The piezoelectric film 24 includes an adhesion layer 71 formed on the surface of the lower electrode 22, a seed layer 72 formed on the adhesion layer 71, and a plurality of PZT layers of the firing unit stacked on the seed layer 72. 73.
The “PZT layer of the main baking unit” refers to a main baking step in which one or a plurality of gelling films formed by gelling a coating film of a precursor solution containing PZT are heat-treated and then subjected to a main baking. This is a PZT layer formed by the following method. The gelling film forming step of forming a gelling film includes a coating step of forming a coating film by applying a precursor solution containing PZT, a drying step of drying the coating film, and gelling the coating film after the drying step. And a calcination step. By performing the main baking after performing the gelling film forming step one or more times, the PZT layer 73 of the main baking unit is formed. That is, the PZT layer 73 of the main firing unit is formed by the sol-gel method.

  The precursor solution contains a solvent in addition to PZT. In the application step, for example, a precursor solution is spin-coated. The drying step is performed, for example, under a temperature environment of 140 ° C. The drying step may be natural drying. In the calcination step, the coating film after the drying step may be subjected to, for example, a heat treatment at a temperature (for example, 300 ° C.) lower than the melting point of lead (327.5 ° C.). In the main baking step, for example, a heat treatment at 700 ° C. is performed on the gelled coating film. This firing step may be performed by RTA (Rapid Thermal Annealing).

The adhesion layer 71 is a layer provided for improving the adhesion between the piezoelectric film 24 and the lower electrode 22. The adhesion layer 71 is made of, for example, a TiO layer. The TiO layer can be formed by, for example, a sol-gel method, a sputtering method, or the like.
The seed layer 72 is a layer provided to improve the crystallinity and adhesion of PZT, and is formed of, for example, a PZT seed layer made of PZT or a TiO seed layer made of TiO. The seed layer 72 is preferably formed by a sputtering method, but may be formed by a sol-gel method. When formed by the sputtering method, since an electric field is generated near the lower electrode 22 during the formation, crystals grow in a polarized state, and the seed layer 72 in which the alignment directions are aligned is obtained. In this case, the seed layer 72 becomes a columnar texture layer composed of crystal grains grown in a columnar shape in the normal direction of the lower electrode 22. When the sol-gel method is used, application of the precursor solution, drying of the coating film, and gelling by heating the dried coating film are sequentially performed to form a single gelled coating film, and the coating film is fully baked. A seed layer 72 is formed. The thickness of the seed layer 72 is, for example, about 5 nm to 500 nm.

In this embodiment, a seed layer 72 (for example, a PZT seed layer) is formed by a sputtering method, and a PZT layer 73 of a plurality of firing units is sequentially stacked on the seed layer 72 by repeating the sol-gel method a plurality of times. Is done. The seed layer formed by the sputtering method forms a columnar texture layer 75, and the PZT layer 73 of the firing unit formed by the sol-gel method forms an amorphous texture layer 76.
The piezoelectric film 24 thus formed is laminated with a seed layer 72 composed of a columnar texture layer 75 and a plurality of final firing layers that are stacked in contact with the seed layer 72 to form an amorphous texture layer 76 of a piezoelectric material. And a unit PZT layer 73. The columnar texture layer 75 has a uniform crystal orientation. The amorphous structure layer 76 has dense film quality and is excellent in withstand voltage. Since the amorphous structure layer 76 is stacked in contact with the columnar structure layer 75, it follows the orientation of the columnar structure layer 75. Therefore, the piezoelectric film 24 in which the columnar texture layer 75 and the amorphous texture layer 76 are laminated has excellent orientation and pressure resistance. Thereby, the inkjet head 1 driven by the piezoelectric element 20 having the piezoelectric film 24 having excellent orientation and withstand voltage can be provided.

  When the columnar texture layer 75 has the <100> orientation, the amorphous texture layer 76 also has a strong tendency to the orientation. In this case, the piezoelectric film 24 has such a property that the displacement due to the inverse piezoelectric effect when applying a voltage is large and the electromotive force due to the piezoelectric effect when deforming is large. On the other hand, when the columnar texture layer 75 has the <111> orientation, the amorphous texture layer 76 also has a strong tendency to the orientation. In this case, the piezoelectric film 24 has such properties that the magnitude of displacement due to the piezoelectric effect when applying a voltage is easily controlled, and that the electromotive force due to the piezoelectric effect when deformed is stable.

  Therefore, by controlling the orientation of the columnar tissue layer 75 according to the required characteristics, the ink jet head 1 having excellent characteristics can be realized. For example, when the columnar tissue layer 75 has the <100> orientation, the displacement of the vibration film 10 can be increased, so that the inkjet head 1 having excellent driving performance can be provided. In addition, when the columnar tissue layer has the <111> orientation, the magnitude of the displacement due to the piezoelectric effect at the time of applying a voltage is easily controlled, so that the inkjet head 1 with excellent controllability can be provided.

  As described above, the columnar tissue layer 75 can be formed by a sputtering method, and thereby, the columnar tissue layer 75 having high orientation controllability can be formed. Then, by forming the piezoelectric material in a polarized state, the columnar tissue layer 75 having high controllability of the orientation can be formed. More specifically, by depositing a piezoelectric material by a sputtering method in a state where an electric field is applied, a columnar tissue layer 75 with a uniform orientation can be formed. As described above, the amorphous structure layer 76 can be formed by the sol-gel method, whereby the dense and high withstand pressure amorphous structure layer 76 can be formed.

If the columnar texture layer 75 and the amorphous texture layer 76 are made of the same type of piezoelectric material (for example, PZT), the orientation of the amorphous texture layer 76 can be more strictly controlled, so that the orientation and the breakdown voltage are excellent. The piezoelectric film 24 can be provided.
Such a piezoelectric film 24 can be applied to a piezoelectric actuator other than the inkjet head 1 and a piezoelectric sensor represented by a microphone and an ultrasonic sensor. That is, in the piezoelectric actuator, by applying a driving voltage between the upper electrode 21 and the lower electrode 22, the piezoelectric film 24 can be deformed by the inverse piezoelectric effect. In the piezoelectric sensor, a voltage can be generated between the upper electrode 21 and the lower electrode 22 by a piezoelectric effect by deforming the piezoelectric film 24 by an external force. By controlling the orientation of the columnar tissue layer 75 according to the required characteristics, a piezoelectric actuator or a piezoelectric sensor having excellent characteristics can be realized. For example, when the columnar tissue layer 75 is in the <100> orientation, the piezoelectric film 24 has a property that the displacement due to the inverse piezoelectric effect at the time of applying a voltage is large and the electromotive force at the time of deformation is large. Therefore, a piezoelectric actuator having excellent driving performance and a piezoelectric sensor having high sensitivity can be realized. When the columnar tissue layer 75 is in the <111> orientation, the piezoelectric film 24 can easily control the magnitude of displacement due to the piezoelectric effect when applying a voltage, and can stabilize the electromotive force due to the piezoelectric effect when deformed. Having. Therefore, a piezoelectric actuator with excellent controllability and a piezoelectric sensor with stable output can be realized.

  FIGS. 9A and 9B are schematic plan views for explaining features of the pattern of the seed layer 72. FIG. The seed layer 72 may be formed on the entire surface of the lower electrode 22, but as shown in FIGS. 9A and 9B, the seed layer 72 is locally formed (hatched for clarity). May be formed. That is, the seed layer 72 is formed in the seed formation region 81 set on the lower electrode 22 (especially the main electrode portion 22A) as a base layer, and the seed layer 72 is formed in the seed non-formation region 82 set on the lower electrode 22. It may not be formed. Then, the piezoelectric material layer may be formed over the seed formation region 81 and the seed non-formation region 82.

  The piezoelectric material formed in contact with the seed layer 72 and the piezoelectric material formed in contact with the underlying layer (lower electrode 22) without contacting the seed layer 72 have different orientations and different characteristics accordingly. Therefore, if a seed forming region 81 in which the seed layer 72 is formed and a non-seed forming region 82 in which the seed layer 72 is not formed and the piezoelectric material layer is formed so as to extend over these regions, an intermediate It is possible to obtain the piezoelectric film 24 having such properties. Therefore, the piezoelectric film 24 having various properties can be obtained by variously determining the area ratio between the seed formation region 81 and the seed non-formation region 82 and the arrangement pattern. Therefore, it is possible to provide the piezoelectric film 24 whose characteristics are controlled according to the application.

  The piezoelectric film 24 includes a first orientation region formed in the seed formation region 81 and oriented in the first direction, and a second orientation region formed in the seed non-formation region 82 and oriented in the second direction. The first alignment region and the second alignment region have different properties according to their alignment directions. Therefore, the piezoelectric film 24 having various properties can be provided according to the area ratio, the arrangement pattern, and the like of the seed formation region 81 and the seed non-formation region 82.

  The orientation direction (first direction) of the piezoelectric material layer in the seed formation region 81 is, for example, <100>. The orientation direction (second direction) of the piezoelectric material layer in the seed non-formation region 82 is, for example, <111>. More specifically, if there is a Pt layer on the surface of the lower electrode 22, a piezoelectric material layer having a <111> orientation is formed under the influence of the orientation. A <100> oriented piezoelectric material layer has a large inverse piezoelectric effect. Therefore, when applied to the piezoelectric element 20, a large displacement characteristic can be obtained, and the discharge amount of the inkjet head 1 can be increased. On the other hand, the piezoelectric performance of the <111> oriented piezoelectric material layer is stable. Therefore, when applied to the piezoelectric element 20, stable driving performance can be obtained, so that the ejection amount of the inkjet head 1 can be accurately and stably controlled. Therefore, by mixing the regions of the piezoelectric material layers having these orientations, it is possible to achieve both stability and strength of the piezoelectric performance according to the required characteristics. That is, by setting the area ratio and the arrangement pattern of the first alignment region and the second alignment region in accordance with the required control accuracy and the required displacement, it is possible to provide the inkjet head 1 having the required drive performance.

  9A and 9B, the seed formation region 81 and the seed non-formation region 82 include a total of three or more separated regions. The seed forming regions 81 and the non-seed forming regions 82 are alternately arranged on the lower electrode 22 (main electrode portion 22A). As described above, since the seed forming regions 81 and the non-seed forming regions 82 are alternately arranged, the piezoelectric material layer easily has intermediate properties. Thereby, the piezoelectric film 24 having high property controllability can be provided.

In the example of FIG. 9A, seed formation regions 81 and non-seed formation regions 82 are alternately arranged in a stripe shape. Accordingly, the degree of orientation mixture increases, so that it is possible to provide the piezoelectric film 24 with higher property controllability.
More specifically, in the example of FIG. 9A, the seed formation region 81 and the seed non-formation region 82 are each formed in a rectangular shape, and one side of an adjacent rectangular shape is overlapped and arranged alternately. The plurality of seed formation regions 81 and the plurality of non-seed formation regions 82 form a rectangular region corresponding to the main electrode portion 22A of the lower electrode 22 as a whole. As described above, the rectangular seed formation regions 81 and the rectangular seed non-formation regions 82 are alternately arranged, so that the rectangular piezoelectric film 24 with high property controllability can be provided.

  In the example of FIG. 9B, an annular seed formation region 81 and an annular seed non-formation region 82 arranged inside or outside the annular seed formation region 81 are provided. By disposing the annular seed forming region 81 and the annular non-seed forming region 82 inside or outside each other, it becomes easy to obtain intermediate characteristics between the characteristics according to the respective orientations. Thereby, the piezoelectric film 24 having high property controllability can be provided.

In addition, by having the annular seed formation region 81, the influence of the characteristics according to the orientation affected by the seed layer 72 can be exerted on a wide range of the piezoelectric film 24, and thereby the characteristic controllability is high. The piezoelectric film 24 can be provided.
Similarly, the presence of the annular non-seed formation region 82 allows the characteristics of the orientation directly influenced by the underlayer (lower electrode 22) to be affected over a wide range of the piezoelectric film 24. Thereby, the piezoelectric film 24 having high property controllability can be provided.

9A and 9B may be formed by a sputtering method or a sol-gel method. The seed layer 72 is preferably formed of a piezoelectric material (for example, PZT).
FIGS. 10A, 10B, 10C, and 10D show modifications of the arrangement of the weights.
In the configuration of FIG. 10A, the upper electrode 21 is covered with the protective film 19, and the weight 65 is disposed on the protective film 19. In this example, the protective film 19 is a laminated film of the hydrogen barrier film 12 and the insulating film 13. The weight 65 may be made of a metal film. The weight 65 is arranged at a position near the center in the short direction of the cavity 6 and extends along the longitudinal direction of the cavity 6. The weight 65 is formed in a band shape having a width shorter than the width of the cavity 6 in the short direction (preferably, about half the width of the cavity 6). Therefore, a sufficient space is secured between the weight 65 and the side edge of the vibration film 10 so as not to hinder the displacement of the vibration film 10. The weight 65 is shorter than the length of the cavity 6 in the longitudinal direction of the cavity 6, and a sufficient space is secured between both ends of the weight 65 and both ends of the cavity 6 so as not to hinder the displacement of the diaphragm 10. Have been. Therefore, there is no possibility that the displacement of the vibration film 10 is greatly restricted by the weight 65.

  In this configuration, since the weight 65 is disposed on the upper electrode 21, the arrangement of the upper electrode 21 and the weight 65 can be determined independently. As a result, a drive voltage can be effectively applied to the piezoelectric film 24, and the arrangement of the weight 65 for realizing excellent drive performance can be determined. Thereby, the inkjet head 1 having excellent driving performance can be realized. Further, since the protective film 19 is disposed between the upper electrode 21 and the weight 65, the weight 65 can be disposed thereon while protecting the upper electrode 21 with the protective film 19.

  In the configuration of FIG. 10B, the weight 65 is arranged on the same layer as the upper electrode 21. The weight 65 is made of the same material (metal material) as the upper electrode 21 and is formed of a film thicker than the upper electrode 21. The weight 65 is arranged near the center of the cavity 6 in a plan view, and the upper electrode 21 has an annular (square annular) shape surrounding the weight 65. A gap is provided between the upper electrode 21 and the weight 65, and they are separated from each other.

In this configuration, since the weight 65 is disposed on the same layer as the upper electrode 21, the same material can be used for the upper electrode 21 and the weight 65, and at least some of them can be formed simultaneously. By making the thickness of the weight 65 larger than that of the upper electrode 21, the inertial mass near the center of the vibration film 10 is locally increased. Thereby, the ink jet head 1 having excellent driving performance can be realized without largely changing the manufacturing process. Further, since the annular upper electrode 21 surrounds the weight 65, the weight 65 can be easily arranged near the center of the diaphragm 10. Thereby, the displacement of the vibration film 10 can be increased. In addition, since the upper electrode 21 has an annular shape surrounding the center of the vibration film 10, the piezoelectric element 20 can be efficiently driven. In this manner, the inkjet head 1 having excellent driving performance can be realized. FIG. 10B shows a structure in which the upper electrode 21 and the weight 65 are separated from each other, but as shown in FIG. They may be connected and integrated. In this case, the upper electrode 21 and the weight 65 have the same potential, and a driving voltage can be applied to the piezoelectric film 24 via the weight 65. That is, the weight 65 also has a function as the upper electrode 21. Thereby, a driving voltage can be applied to a wide range of the piezoelectric film 24 and the displacement of the vibration film 10 by the weight 65 can be increased, so that the inkjet head 1 having excellent driving performance can be realized.

  In the configuration shown in FIG. 10D, a lead electrode 66 crossing the upper electrode 21 is formed from the weight 65 formed on the same layer as the upper electrode 21. The upper electrode 21 is formed in a horseshoe shape having both ends separated with the extraction electrode 66 interposed therebetween. Gaps are formed between the upper electrode 21 and the weight 65 and between the upper electrode 21 and the extraction electrode 66, and they are separated from each other.

  With this configuration, the weight 65 can be easily arranged near the center of the vibration film 10 and the upper electrode 21 can effectively apply a drive voltage to the piezoelectric film 24, so that the inkjet head 1 with excellent drive performance is realized. it can. In addition, since the extraction electrode 66 extracted from the weight 65 is not in contact with the upper electrode 21, a voltage can be independently applied to the weight 65 and the upper electrode 21. Thereby, a driving method that further improves the driving performance can be adopted.

  The piezoelectric device using the weight is not limited to the inkjet head. That is, the piezoelectric device may include a vibration film, a piezoelectric element disposed on the vibration film, and a weight disposed so as to locally increase the inertial mass near the center of the vibration film. Such a piezoelectric device may be a piezoelectric actuator or a piezoelectric sensor. An ink jet head is a type of piezoelectric actuator.

In a piezoelectric actuator, when a driving voltage is applied to a piezoelectric element, the piezoelectric element is deformed by an inverse piezoelectric effect, and the vibrating membrane is displaced accordingly. Since the weight is arranged to locally increase the inertial mass at the center of the diaphragm, the displacement of the diaphragm can be increased. Thus, a piezoelectric actuator having excellent driving performance can be realized.
In the piezoelectric sensor, when the vibrating membrane is displaced, a voltage is generated in the piezoelectric element by a piezoelectric effect. Since the weight is arranged to locally increase the inertial mass at the center of the diaphragm, the displacement of the diaphragm can be increased. As a result, a large voltage is generated in the piezoelectric element, so that a piezoelectric sensor having excellent detection performance (especially, sensitivity) can be realized. Examples of the piezoelectric sensor include a microphone and an ultrasonic sensor.

FIGS. 11A to 11I show modifications of the starting point of the displacement of the piezoelectric film 24.
In the configuration of FIG. 11A, a pair of dot-shaped concave portions 85 as starting points are formed near both ends of the upper electrode 21. The recess 85 may or may not penetrate the upper electrode 21. The concave portion 85 is an example of a bent portion, and has a concave shape in the stacking direction of the upper electrode 21, the lower electrode 22, and the piezoelectric film 24. Further, since at least a part of the upper electrode 21 is removed in the concave portion 85, the concave portion 85 is a fragile portion that is more fragile than other portions of the piezoelectric element 20. The recess 85 is arranged in a region inside the periphery of the piezoelectric element 20 and is separated from the periphery of the piezoelectric element 20. In this example, the concave portion 85 has a rectangular dot shape, but may have another shape such as a polygon, a circle, and an ellipse.

  According to this configuration, the concave portion 85 as the starting point is disposed in a region inside the peripheral edge of the piezoelectric element 20 and is separated from the peripheral edge of the piezoelectric element 20, so that the displacement of the piezoelectric film 24 is reduced as a whole. Easy to propagate. Therefore, the inkjet head 1 with high responsiveness can be provided, and accordingly, the inkjet head 1 with high operation control can be realized. In addition, since the concave portion 85 as a starting point can be provided by processing the upper electrode 21, the inkjet head 1 with high operation controllability can be realized with a simple manufacturing process. Since the displacement of the piezoelectric film 24 starts from the concave portion 85 as the starting point, a stable response and a stable displacement corresponding to the driving voltage can be obtained. Thereby, it is possible to provide the inkjet head 1 capable of performing stable and accurate operation control. Further, since the displacement of the piezoelectric film 24 can be started from the vicinity of both ends of the cavity 6, it is possible to provide the ink jet head 1 which is excellent not only in operation controllability but also in response to driving voltage.

  In the configuration of FIG. 11B, the starting point is formed by a groove 86 that is a recess formed in the upper electrode 21. The groove 86 may or may not penetrate the upper electrode 21 in the film thickness direction. The groove 86 is provided near both ends in the longitudinal direction of the cavity 6, has a concave shape in the stacking direction, and provides a fragile portion that is more fragile than other portions of the piezoelectric element 20. The groove 86 extends along the short direction of the cavity 6, that is, along the periphery of the piezoelectric element 20, and extends over the entire width of the upper electrode 21. Thereby, the groove 86 extends from the region inside the piezoelectric element 20 toward the peripheral edge of the piezoelectric element 20 and is in contact with the peripheral edge of the piezoelectric element 20. Therefore, the groove 86 is formed by processing a region continuous with the peripheral edge of the piezoelectric element 20. In this example, the groove 86 is formed in a straight line, but may be a broken line or a curved line.

  According to this configuration, the groove 86 as a starting point extends from a region inside the periphery of the piezoelectric element 20 toward the periphery of the piezoelectric element 20 and is in contact with the periphery of the piezoelectric element 20. Since the groove 86 as the starting point is in contact with the peripheral edge of the piezoelectric element 20, the displacement of the piezoelectric film 24 easily starts. Accordingly, the piezoelectric element 20 with high responsiveness can be provided, and accordingly, the inkjet head 1 with high operation control can be realized. Further, since the groove 86 as the starting point extends along the peripheral edge of the piezoelectric element 20, the displacement of the piezoelectric film 24 can be reliably started in a wide range, and accordingly, the inkjet having high operation controllability is correspondingly provided. The head 1 can be realized.

  In the configuration in FIG. 11C, notches 87 are formed at positions near both ends of the cavity 6 on both side edges along the longitudinal direction of the upper electrode 21. The notch 87 has a bent shape in a plan view, and is an example of a concave shape that is depressed inward of the upper electrode 21. Specifically, the notch 87 has a recessed shape along a direction intersecting (orthogonal to) the laminating direction of the upper electrode 21 and the piezoelectric film 24. Notch 87 may or may not penetrate upper electrode 21 in the film thickness direction. The notch 87 provides a fragile portion that is fragile compared to other portions of the piezoelectric element 20. The notch 87 is in contact with the peripheral edge of the piezoelectric element 20 and is formed by processing a region continuous with the peripheral edge of the piezoelectric element 20.

  The notch 87 provides a starting point from which the displacement starts when a driving voltage is applied to the piezoelectric element 20. Therefore, it is possible to provide the ink jet head 1 in which the operation control is easy and the operation can be performed with high accuracy. Further, since the notch 87 as the starting point is in contact with the peripheral edge of the piezoelectric element 20, the displacement of the piezoelectric film 24 easily starts. Thereby, the piezoelectric element 20 with high responsiveness can be provided, and accordingly, the inkjet head 1 with high operation control can be provided. Since the notch 87 can be formed at the same time when the periphery of the piezoelectric element 20 (more specifically, the periphery of the upper electrode 21) is processed, the piezoelectric element 20 with high operation control can be realized without increasing the number of manufacturing steps. . Further, since the displacement of the piezoelectric film 24 can be started from the vicinity of both ends of the cavity 6, it is possible to provide the ink jet head 1 which is excellent not only in operation controllability but also in response to driving voltage.

  In the configuration of FIG. 11D, the starting point is formed by a pair of grooves 88 that are recesses formed in the upper electrode 21. The groove 88 may or may not penetrate the upper electrode 21 in the film thickness direction. The grooves 88 are provided along both sides along the longitudinal direction of the cavity 6, that is, along the periphery of the piezoelectric element 20, in the vicinity of the both sides. The groove 88 has a concave shape in the laminating direction of the upper electrode 21 and the piezoelectric film 24, and provides a fragile portion that is more fragile than other portions of the piezoelectric element 20. The groove 88 is arranged at a distance from the side edge of the upper electrode 21 along the short direction of the cavity 6. The groove 88 extends linearly and continuously from near one end of the upper electrode 21 in the longitudinal direction to near the other end. Both ends thereof are arranged at an interval from both ends of the upper electrode 21. Therefore, the groove 88 is separated from the peripheral edge of the piezoelectric element 20. Since the groove 88 extends along the longitudinal direction of the cavity 6, the displacement of the piezoelectric film 24 starts in a wide range in response to the application of the driving voltage. This makes it possible to provide the ink jet head 1 that is excellent not only in operation controllability but also in response to a drive voltage. The groove 88 may have a polygonal line shape or a curved shape other than the linear shape.

The configuration of FIG. 11E is similar to the configuration of FIG. 11D, except that the grooves 89 linearly extending along the longitudinal direction of the cavity 6 are discontinuous. With this configuration, the same effect as the configuration in FIG. 11D can be obtained.
11D and 11E, the grooves 88 and 89 may extend from one end to the other end of the upper electrode 21 and may be in contact with the periphery of the piezoelectric element 20. However, in this case, it is preferable that the upper electrode 21 be left at least partially at the bottom of the continuous groove 88 shown in FIG. 11D so that the upper electrode 21 is not separated between the inside and the outside of the groove 88.

  In the configuration shown in FIG. 11F, an annular groove 90 extending along the periphery of the piezoelectric element 20 is formed in the upper electrode 21. In this example, since the upper electrode 21 has a rectangular shape, a rectangular annular groove 90 is formed. The groove 90 includes a pair of long sides 91 extending along the longitudinal direction of the cavity 6 and a pair of short sides 92 extending along the short direction of the cavity 6. The long side portion 91 is arranged near the side edge of the upper electrode 21 (that is, the periphery of the piezoelectric element 20) with an interval from the side edge. The short sides 92 are arranged near both ends of the upper electrode 21 (that is, the periphery of the piezoelectric element 20) with a space from the ends. Therefore, the annular groove 90 does not contact the peripheral edge of the piezoelectric element 20. It is preferable that the upper electrode 21 be left at least partially at the bottom of the groove 90 so that the upper electrode 21 is not separated inside and outside the annular groove 90.

The configuration in FIG. 11G is similar to the configuration in FIG. 11F, except that the annular groove 93 is discontinuous. In the case of this configuration, the groove 93 may penetrate the upper electrode 21 in all parts.
In the configuration of FIG. 11H, substantially arc-shaped concave portions 94 are formed at four corners of the rectangular upper electrode 21. The concave portion may or may not penetrate the upper electrode 21. The concave portion has an arc shape bulging toward a corner of the upper electrode 21. The recesses are located near both ends in the longitudinal direction of the cavity 6, and are respectively located near both ends in the short direction of the cavity 6. The recess is formed separately from the periphery of the piezoelectric element 20. Also according to this configuration, when a driving voltage is applied to the piezoelectric element 20, deformation of the piezoelectric film 24 and the vibration film 10 starts with the concave portion as a starting point of displacement. Thereby, a stable and highly responsive ink jet head 1 can be realized.

  The configuration of FIG. 11I is similar to the configurations shown in FIGS. In the configuration shown in FIGS. 2 to 5, an annular thin film portion 26 is provided on the periphery of the piezoelectric film 24. On the other hand, in the configuration of FIG. 11I, a pair of thin film portions 96 are provided along both sides along the longitudinal direction of the piezoelectric film 24. The thin film portion 96 is formed over the entire length from one end to the other end in the longitudinal direction of the piezoelectric film 24. The thin film portions 96 are formed only at the both ends in the short direction at both ends in the longitudinal direction of the piezoelectric film 24, and the thick film portion 95 exists between them. The thin film portion 96 is in contact with the peripheral edge of the piezoelectric element 20.

  The feature that the piezoelectric element is provided with a starting point of a peculiar shape (for example, a bent shape) serving as a starting point of displacement can be applied not only to the ink jet head 1 but also to other types of piezoelectric actuators such as a piezoelectric speaker. Can also be applied. In the piezoelectric sensor, when an external force is applied to the piezoelectric film, a voltage is generated between the upper electrode and the lower electrode by a piezoelectric effect. When an external force is applied, the deformation (displacement) of the piezoelectric film can be guaranteed to start from the starting point, so that the deformation (displacement) of the piezoelectric film similarly occurs for a plurality of piezoelectric elements and a plurality of external forces. . Thereby, the detection sensitivity is stabilized, and a highly accurate operation can be performed. Examples of the piezoelectric sensor include a microphone and an ultrasonic sensor.

FIGS. 12A and 12B show a modified example relating to the feature of providing a third electrode in addition to the upper electrode 21 (first electrode) and the lower electrode 22 (second electrode).
In the configuration of FIG. 12A, the operation monitoring electrode 100 is disposed on the same layer as the upper electrode 21. The operation monitoring electrode 100 enters the notch 101 formed on the upper electrode 21 and faces the lower electrode 22 via the piezoelectric film 24. The operation monitoring electrode 100 faces the cavity 6. The operation monitoring electrode 100 is formed linearly, and has only one terminal portion 102. The terminal part 102 is arranged outside the notch part 101. In this example, the notch portion 101 has a shape that is elongated linearly in the longitudinal direction of the cavity 6 from an intermediate position of the edge of the upper electrode 21. The operation monitoring electrode 100 extends linearly at least in the notch 101 so as to correspond to the shape of the notch 101. The operation monitoring electrode 100 is arranged at an interval from the periphery of the notch 101, and is therefore electrically separated from the upper electrode 21.

When the piezoelectric film 24 is deformed when a driving voltage is applied between the upper electrode 21 and the lower electrode 22, an electromotive force generated by the deformation is generated between the operation monitoring electrode 100 and the lower electrode 22. Therefore, by providing a detection circuit for detecting a potential difference between the operation monitoring electrode 100 and the lower electrode 22, the operation state of the piezoelectric film 24 can be monitored.
In the configuration of FIG. 12B, an intermediate electrode 103 as a third electrode is in contact with the piezoelectric film 24 between the upper electrode 21 and the lower electrode 22. More specifically, the intermediate electrode 103 is disposed at a position intermediate the film thickness of the piezoelectric film 24. The intermediate electrode 103 is parallel to the upper electrode 21 and the lower electrode 22 and faces the upper electrode 21 and the lower electrode 22 with the piezoelectric film 24 interposed therebetween. Since the intermediate electrode 103 is thus embedded in the piezoelectric film 24, the state of the piezoelectric film 24 can be monitored more accurately by using the intermediate electrode 103.

  Further, since the piezoelectric film 24 is interposed between the intermediate electrode 103 and the lower electrode 22 and between the intermediate electrode 103 and the upper electrode 21, respectively, between the intermediate electrode 103 and the upper electrode 21, By applying a drive voltage between the intermediate electrode 103 and the lower electrode 22, the deformation of the piezoelectric film 24 can be caused. Therefore, it is possible to provide the inkjet head 1 that can operate in a number of operation modes. For example, the piezoelectric element 20 may be driven by setting the upper electrode 21 and the lower electrode 22 to the ground potential and applying a drive voltage to the intermediate electrode 103.

  The feature of having a third electrode in addition to the upper electrode (first electrode) and the lower electrode (second electrode) applies not only to piezoelectric actuators such as ink jet heads but also to piezoelectric sensors such as microphones and ultrasonic sensors. it can. For example, if the configuration shown in FIG. 6 or FIG. 12A is applied to a piezoelectric sensor, when an external force is applied to the piezoelectric film 24, the third electrode is added to the detection output signals from the upper electrode 21 and the lower electrode 22. By detecting a detection signal from 23 (operation monitoring electrode), the external force applied to the piezoelectric film 24 can be detected in more detail. In other words, a piezoelectric sensor having a number of detection modes can be provided. Also. If the configuration shown in FIG. 12B is applied to a piezoelectric sensor, when an external force is applied to the piezoelectric film 24, an electromotive force is generated between the upper electrode 21 or the lower electrode 22 and the intermediate electrode 103. A piezoelectric sensor having a mode can be provided.

FIGS. 13A to 13D show modifications related to the shape of the cavity 6.
In the configuration shown in FIG. 13A, the inner wall surface 62 of the actuator substrate 2 has a recess 62C that is recessed outside the cavity 6. The concave portion 62C forms a valley portion that forms an obtuse angle in a cross section that intersects the surface of the vibration film 10 on the cavity 6 side. The lower edge of the first flat surface portion 62D is continuous with the upper side (the actuator substrate 2 side) of the concave portion 62C. The first flat surface portion 62D is inclined with respect to both the direction parallel to the vibration film 10 and the normal direction of the vibration film 10. The upper edge of the first flat surface portion 62D is continuous with the curved surface portion 62A. Below the concave portion 62C (on the nozzle substrate 3 side), a second flat surface portion 62E is continuous with the concave portion 62C. The second flat surface portion 62E is inclined with respect to both the direction parallel to the vibration film 10 and the normal direction of the vibration film 10. The first flat surface portion 62D is inclined outward from the cavity 6 from the curved surface portion 62A toward the recessed portion 62C. The second flat surface portion 62E is inclined outward from the cavity 6 from the nozzle substrate 3 toward the recessed portion 62C. A plane including the first flat surface portion 62D and a plane including the second flat surface portion 62E form an obtuse angle in a cross section intersecting the surface of the vibration film 10 on the cavity 6 side. That is, the recess 62C forms an obtuse angle in the cross section.

  In this configuration, since the depression 62C forms an obtuse valley, trapping of bubbles in the depression 62C can be suppressed or prevented. Thereby, the ink ejection control performance can be improved. Further, it is easy to form the inner wall surface 62 having the first flat surface portion 62D and the second flat surface portion 62E, and since the intersections (recesses) form an obtuse angle, the air bubbles at the intersections are formed. The accumulation can be suppressed or prevented. This makes it possible to provide the inkjet head 1 in which the manufacturing process is easy and the ink ejection control performance is improved.

The configuration shown in FIG. 13B is similar to the configuration of FIG. 13A, except that the recess 62C has no corner and the inner surface is a curved surface. Since the concave portion 62C forms a curved surface, trapping of bubbles in the concave portion 62C can be more effectively suppressed or prevented. Thereby, the ink ejection control performance can be improved.
In the configuration shown in FIG. 13C, the curved surface portion 62A that is in contact with the lower surface of the vibration film 10 is continuous from one surface of the actuator substrate 2 to the other surface. Accordingly, it is possible to suppress or prevent the generation of air bubbles on the inner wall surface of the cavity 6. Moreover, since the curved surface portion 62 </ b> A is also in contact with the nozzle substrate 3, it is difficult for air bubbles to be captured at the boundary between the inner wall surface 62 of the cavity 6 and the nozzle substrate 3. Therefore, the ink jet head 1 with further improved ink discharge control performance can be realized. The curved surface portion 62 </ b> A preferably extends over the entire circumference of the boundary between the inner wall surface 62 of the cavity 6 and the nozzle substrate 3. This makes it possible to more reliably suppress the accumulation of bubbles.

  In the configuration shown in FIG. 13D, the inner wall surface 62 of the cavity 6 has a curved surface portion 62F that is curved outward and spreads out on the nozzle substrate 3 side. The lower edge of the curved surface portion 62F is in contact with the nozzle substrate 3. According to this configuration, since the inner wall surface 62 of the cavity 6 also has the curved surface portion 62F on the nozzle substrate 3 side, it is possible to suppress or prevent the accumulation of bubbles at the intersection between the nozzle substrate 3 and the inner wall surface 62. Thereby, it is possible to provide the ink jet head 1 with improved ink discharge control performance. The curved surface portion 62F preferably extends over the entire periphery of the boundary between the inner wall surface 62 of the cavity 6 and the nozzle substrate 3. This makes it possible to more effectively suppress or prevent the accumulation of air bubbles at the intersection between the inner wall surface of the cavity 6 and the nozzle substrate 3, and to improve the ink discharge control performance accordingly. When the vibrating film 10 is disposed above the nozzle substrate 3, the trapping of bubbles on the nozzle substrate 3 side does not need to be considered so much because air bubbles accumulate on the vibrating film 10 side.

FIG. 14A and FIG. 14B show modified examples relating to the feature of separation of the vibration film 10 for each cavity 6.
As shown in FIG. 14A, the separation groove 60 for separating the vibration film 10 between the cavities 6 may be a groove having a discontinuous pattern. Even in the case of such a discontinuous pattern groove, it is possible to reduce the constraint on the vibration film 10 corresponding to each cavity 6 from the surroundings.

  As shown in FIG. 14B, the separation groove 60 may further extend from a partition wall 61 that partitions the pair of adjacent cavities 6 and may be formed in a pattern surrounding the cavities 6. Thereby, the restraint from the surroundings on the vibration film 10 can be further reduced, so that the displacement of the vibration film 10 and the partition wall can be further increased. In the example of FIG. 14B, the separation groove 60 includes a side edge separation groove 60a extending along the side edge of the cavity 6, and an edge separation groove 60b extending along the edge of the cavity 6. Edge separation grooves 60b are respectively connected to both ends of the side edge separation groove 60a. The side edge separation groove 60a and / or the edge separation groove 60b may be a groove having a discontinuous pattern.

FIGS. 15A, 15B, and 15C show modified examples relating to the characteristics of the arrangement of the driving ICs 5. FIG.
In the configuration of FIG. 15A, the drive IC 5 is mounted on the surface of the actuator substrate 2 so as to cover the piezoelectric element 20. Therefore, the drive IC 5 also serves as a protection substrate for protecting the piezoelectric element 20. Thus, there is no need to separately provide a protection substrate for protecting the piezoelectric element 20. In addition, since the driving IC 5 can be mounted on the actuator substrate 2 so as to overlap the piezoelectric element 20, the size of the inkjet head 1 can be further reduced.

  The drive IC 5 has a concave portion 5c formed on a first surface 5a (opposing surface) facing the surface of the actuator substrate 2. The piezoelectric element 20 is accommodated in the recess 5c. Thereby, an operation space for operating the piezoelectric element 20 can be secured, and the height of the upper surface (the second surface 5b; the surface opposite to the actuator substrate 2) of the drive IC 5 can be reduced. Thereby, a small-sized inkjet head 1 can be realized while securing an operation space for the piezoelectric element 20.

  The configuration shown in FIG. 15B is similar to the configuration of FIG. 15A, except that the FPC 57 is directly joined to the input terminal 56 disposed on the upper surface (second surface 5b) of the drive IC 5. This eliminates the need for wire bonding between the input terminal 56 of the drive IC 5 and the FPC 57, so that there is no need to provide a space for wire bonding on the actuator substrate 2. Thereby, the size of the inkjet head 1 can be further reduced.

In the configuration shown in FIG. 15C, the drive IC 5 has a flat opposing surface opposing the surface of the actuator substrate 2 as a first surface 5a, and a bump 53 forming an output terminal is formed on the first surface 5a. ing. The drive IC 5 is mounted on the actuator substrate 2 so as to cover the piezoelectric element 20.
A gap 7 is formed between the surface of the actuator substrate 2 and the first surface 5 a of the drive IC 5 by the bump 53, and the piezoelectric element 20 is disposed in the gap 7, and is formed on the flat first surface 5 a of the drive IC 5. Are facing each other. Thus, the space formed by the bumps 53 is used as a space for arranging and operating the piezoelectric element 20. Thus, there is no need to form a recess in the first surface 5a of the driving IC 5, so that the manufacturing process is simplified.

Although the embodiments of the present invention have been described above, the present invention can be embodied in other forms. For example, features related to piezoelectric elements can be applied not only to ink-jet heads but also to microphones, pressure sensors, acceleration sensors, angular velocity sensors, ultrasonic sensors, speakers, IR sensors (thermal sensors), etc. Can be.
In addition, various design changes can be made within the scope of the matters described in the claims.

From the description of this specification and the accompanying drawings, the following features can be extracted in addition to the features described in the claims.
A1. A substrate having an inner wall surface that defines a cavity for storing ink,
A vibrating membrane supported by the substrate and defining the cavity;
A piezoelectric element provided on the vibration film to displace the vibration film to cause a change in volume of the cavity,
An ink jet head, wherein an inner wall surface of the substrate has a curved surface portion continuous with a surface of the vibration film on the cavity side.

  At the corner formed by the side wall of the cavity and the lower surface of the vibrating membrane, bubbles in the ink are likely to be trapped, causing the accumulation of bubbles. If there is a bubble pool in the cavity, when the volume of the cavity changes due to deformation of the vibrating membrane, a part of the volume change may be absorbed by the shrinkage of the bubble. Therefore, there is a possibility that an amount of ink corresponding to the driving voltage is not ejected.

Thus, the configuration of item A1 provides an ink jet head with improved ink discharge controllability.
In the configuration of the term A1, the ink in the cavity is ejected by driving the piezoelectric element to change the volume of the cavity. The inner wall surface of the substrate that defines the cavity has a curved surface portion that continues to the cavity-side surface of the vibration film. Therefore, even if bubbles are included in the ink, the bubbles are hardly captured in the cavity, and are quickly discharged together with the ink. As a result, it is possible to suppress or prevent the formation of air bubbles in the cavity. As a result, it is possible to suppress or prevent the change in the volume of the cavity from being absorbed by the contraction of the bubbles, so that it is possible to accurately achieve the ink ejection amount corresponding to the drive voltage applied to the piezoelectric element. Thus, an ink jet head with improved ink discharge controllability can be provided.

A2. The curved surface portion is connected to a contact point with the vibration film in a cross section intersecting the surface of the vibration film on the cavity side, and has a curved portion extending from the outside of the cavity to the contact point. Inkjet head.
According to this configuration, the curved surface portion formed on the inner wall surface of the substrate has a shape that recedes from the position in contact with the vibration film to the outside of the cavity. Thus, no corners are formed between the inner wall surface of the substrate and the vibrating membrane, and thus, the accumulation of bubbles hardly occurs. Thus, an ink jet head with improved ink discharge controllability can be provided.

A3. The ink jet head according to item A1 or A2, wherein the curved surface portion is continuous from one surface to the other surface of the substrate.
With this configuration, it is possible to realize an ink jet head with improved ink ejection control performance.
A4. The ink jet head according to item A1 or A2, wherein the inner wall surface of the substrate has a flat surface portion connected to the curved surface portion.

With this configuration, since the inner wall surface of the substrate extends from the curved surface portion to the flat surface portion, it is possible to suppress or prevent bubbles in the ink from being captured by the inner wall surface of the substrate.
A5. The ink jet head according to item A4, wherein the inner wall surface of the substrate has a concave portion that is depressed outside the cavity.
A6. The ink jet head according to item A5, wherein the depression forms a valley that forms an obtuse angle in a cross section that intersects the surface of the vibration film on the cavity side.

Since the depressions form obtuse valleys, trapping of bubbles in the depressions can be suppressed or prevented. Thereby, the ink ejection control performance can be improved.
A7. The ink jet head according to item A5, wherein the recessed portion forms a curved surface.
With this configuration, it is possible to more effectively suppress or prevent trapping of air bubbles in the depression. Thereby, the ink ejection control performance can be improved.

A8. A first flat surface portion, which is the flat surface portion connected to the curved surface portion, is connected to the depression,
The inner wall surface of the substrate further includes a second flat surface portion connected to the recess on a side opposite to the first flat surface portion,
Any of the terms A5 to A7, wherein a plane including the first flat surface portion and a plane including the second flat surface portion form an obtuse angle in a cross section that intersects with the cavity-side surface of the vibration film. The inkjet head according to claim 1.

It is easy to form the inner wall surface of the substrate having the first flat surface and the second flat surface. And the intersection of the planes containing them respectively forms an obtuse angle. Therefore, it is possible to suppress or prevent the accumulation of bubbles in the depression. This makes it possible to provide an ink jet head whose manufacturing process is easy and ink ejection control performance is improved.
A9. A nozzle substrate coupled to an opposite side of the vibration film of the substrate and having an ink discharge passage communicating with the cavity;
The inkjet head according to any one of Items A1 to A8, wherein the inner wall surface of the substrate has a second curved surface portion that is continuous with the surface of the nozzle substrate on the cavity side.

According to this configuration, since the inner wall surface of the substrate also has a curved surface portion on the nozzle substrate side, it is possible to suppress or prevent the accumulation of bubbles at the intersection between the nozzle substrate and the inner wall surface of the substrate. Thus, an ink jet head with improved ink ejection control performance can be provided.
A10. The ink jet head according to item A9, wherein the second curved surface portion extends over the entire circumference of a boundary between the inner wall surface of the substrate and the nozzle substrate.
With this configuration, it is possible to more effectively suppress or prevent the accumulation of bubbles at the intersection between the inner wall surface of the substrate and the nozzle substrate, and to improve the ink discharge control performance accordingly.

A11. The inkjet head according to any one of Items A1 to A10, wherein the curved surface portion extends over the entire circumference of a boundary between the inner wall surface of the substrate and the vibration film.
With this configuration, the accumulation of bubbles at the intersection between the inner wall surface of the substrate and the vibration film can be more effectively suppressed or prevented, and accordingly, the ink discharge control performance can be improved.
B1. An actuator substrate that defines a cavity in which ink is stored;
A vibrating membrane supported by the actuator substrate and defining the cavity;
A piezoelectric element provided on the vibration film to change the volume of the cavity by displacing the vibration film,
A drive IC mounted on the actuator substrate and driving the piezoelectric element,
The driving IC is
A plurality of output terminals that are centrally arranged on the first surface facing the actuator substrate and are joined to the actuator substrate;
A plurality of input terminals disposed on a second surface opposite to the first surface;
Ink jet head.

  In the related art, a drive IC for driving a piezoelectric element is disposed on, for example, a substrate different from an actuator substrate on which the piezoelectric element is formed. For example, about 300 cavities and corresponding piezoelectric elements are mounted on the actuator substrate. These piezoelectric elements and the driving IC are connected via an FPC (flexible printed circuit board). More specifically, one end of the FPC is fixed on the actuator substrate, and the electrodes of the piezoelectric element and the plurality of core wires of the FPC are wire-bonded. On the other hand, the other end of the FPC is fixed on a substrate on which the drive IC is mounted, and the drive IC and a plurality of core wires of the FPC are wire-bonded.

  The drive IC has, for example, about 300 output pins and about 20 input pins. Of these, about 300 output pins are connected to the piezoelectric elements on the actuator substrate via the FPC. About 20 input pins are connected to a control IC via another FPC or the like. Therefore, it is necessary to secure, on the actuator substrate, a place for fixing an FPC having about 300 core wires and a space for wire bonding for connecting those core wires to electrodes of about 300 piezoelectric elements. is there. Further, an FPC having about 300 core wires occupies a large space. For these reasons, there is a problem that the size of the ink jet head is increased.

Therefore, the configuration of item B1 provides an inkjet head having a structure advantageous for miniaturization.
According to the configuration of Item B1, when the drive IC applies a drive voltage to the piezoelectric element, the vibration film is displaced together with the piezoelectric element, causing a change in the volume of the cavity. Thereby, the ink in the cavity is ejected. The drive IC includes a plurality of output terminals concentrated on a first surface facing the actuator substrate, and the plurality of output terminals are joined to the actuator substrate. That is, the drive IC is mounted on the actuator substrate. In addition, the drive IC includes a plurality of input terminals arranged on a second surface opposite to the first surface. The plurality of input terminals may be connected to, for example, a control IC.

Since the output terminals of the drive IC are concentrated on the first surface on the actuator substrate side and are bonded to the actuator substrate, a cable (for example, FPC) for connecting the actuator substrate to the output terminal of the drive IC Is unnecessary. As a result, the size of the inkjet head can be reduced.
In general, a drive IC for driving an ink jet head has more output terminals than input terminals. Therefore, significant space saving can be achieved by eliminating a cable connected to the output terminal.

The concentrated arrangement of the output terminals means that most of the output terminals (preferably all the output terminals) of the driving IC are arranged on the first surface. However, this does not prevent the input terminals from being arranged on the first surface.
A plurality of input terminals may be centrally arranged on the second surface. That is, most input terminals (for example, all input terminals) of the drive IC may be arranged on the second surface.

B2. The drive IC connects a semiconductor substrate, an active region on a side of the semiconductor substrate opposite to the actuator substrate, on which a semiconductor device is formed, and the active region and the output terminal through the semiconductor substrate. The ink-jet head according to item B1, which includes a through via.
In this configuration, in the semiconductor substrate of the drive IC, an active region is arranged on the side opposite to the actuator substrate, and the active region and the output terminal are connected by a through via (for example, TSV: Through Silicon Via). Thus, the output terminals can be centrally arranged on the first surface of the drive IC on the actuator substrate side. The drive IC having the through via does not need to route the wiring from the active region to the non-active surface side outside the semiconductor substrate, so that the drive IC itself can be made small. This can contribute to downsizing of the ink jet head.

B3. The ink-jet head according to paragraph B1 or B2, wherein a flexible printed circuit board is connected to the plurality of input terminals via bonding wires.
Since the number of input terminals of the drive IC is not so large, even if connection between the input terminals and the flexible printed circuit board is performed by wire bonding, the size of the ink jet head is not so large.
B4. The ink-jet head according to paragraph B1 or B2, wherein a flexible printed board is directly connected to the plurality of input terminals.

In this configuration, since the wire bonding between the input terminal of the drive IC and the flexible printed board is unnecessary, a space for wire bonding does not need to be provided. Thereby, the size of the inkjet head can be further reduced.
B5. The inkjet head according to any one of Items B1 to B4, wherein the drive IC is mounted on a surface of the actuator substrate so as to cover the piezoelectric element.

  In this configuration, the drive IC is disposed so as to cover the piezoelectric element, and also serves as a protection substrate for protecting the piezoelectric element. Thus, there is no need to separately provide a protection substrate for protecting the piezoelectric element. In addition, since the drive IC can be mounted on the actuator substrate so as to overlap the piezoelectric element, the size of the ink jet head can be further reduced.

B6. The ink jet head according to paragraph B5, wherein the drive IC is formed on a surface facing the surface of the actuator substrate, and has a recess for housing the piezoelectric element.
Thereby, an operation space for operating the piezoelectric element can be secured, and the height of the upper surface of the drive IC (the surface opposite to the actuator substrate) can be reduced. This makes it possible to realize a small-sized inkjet head while securing an operation space for the piezoelectric element.

B7. The drive IC has a flat facing surface facing the surface of the actuator substrate,
A bump constituting the output terminal is formed on the facing surface,
A gap is formed between the surface of the actuator substrate and the opposing surface by the bump,
The ink jet head according to paragraph B5, wherein the piezoelectric element is arranged in the gap and faces the flat opposing surface.

In this configuration, the output terminal has the form of a bump, thereby securing a space between the opposing surface of the drive IC and the actuator substrate. This space is used as a space for arranging the piezoelectric element and operating the piezoelectric element. This simplifies the manufacturing process because it is not necessary to form a recess on the opposing surface of the drive IC.
B8. An inkjet head driving IC mounted on an actuator substrate having a piezoelectric element for discharging ink, and for driving the piezoelectric element,
A plurality of output terminals, which are centrally arranged on the first surface facing the actuator substrate and are joined to the substrate;
And a plurality of input terminals disposed on a second surface opposite to the first surface.

With this configuration, a drive IC advantageous for downsizing the ink jet head is provided.
B9. A semiconductor substrate, an active region disposed on a side of the semiconductor substrate opposite to the actuator substrate, on which a semiconductor device is formed, and a through via connecting the active region and the output terminal through the semiconductor substrate. The inkjet head drive IC according to item B8.

B10. The ink jet head driving IC according to any one of Items B8 and B9, further including a concave portion formed on a surface facing the surface of the actuator substrate and accommodating the piezoelectric element.
B11. Having a flat opposing surface opposing the surface of the actuator substrate,
A bump constituting the output terminal is formed on the facing surface,
The ink jet head driving IC according to any one of Items B8 and B9, wherein the bump has a height such that a gap capable of accommodating the piezoelectric element is secured between the surface of the actuator substrate and the opposing surface.

Reference Signs List 1 inkjet head 2 actuator substrate 3 nozzle substrate 4 protective substrate 6 cavity 8 ink tank 10 vibration film 11 vibration film formation layer 12 hydrogen barrier film 13 insulating film 15 wiring 16 land 19 protection film 20 piezoelectric element 21 upper electrode 22 lower electrode 22A main Electrode part 22B Extension part 22C Land 23 Operation monitoring electrodes 23a, 23b Terminal part 24 Piezoelectric film 25 Thick film part 26 Thin film part 27 Bend part 28 Step surface 31 Ink discharge passage 32 Discharge port 35 Notch part 36 Drive state monitoring circuit 41 Surface 42 Storage recess 43 Ink supply path 44 Ink supply path 45 Ink flow direction 49 Common ink path 50 Ink path 51 Semiconductor substrate 52 Active area 53 Bump (output terminal)
54 Protective resin layer 55 Through via 56 Input terminal 57 FPC
58 Bonding wire 60 Separation groove 60a Side edge separation groove 60b Edge separation groove 61 Partition wall 62 Inner wall surface 62A Curved surface portion 62B Flat surface portion 62C Depressed portion 62D First flat surface portion 62E Second flat surface portion 62F Curved surface portion 65 Weight 66 Pull-out Electrode 71 Adhesion layer 72 Seed layer 73 PZT layer 75 of main firing unit Columnar texture layer 76 Amorphous texture layer 81 Seed formation area 82 No seed formation area 85 Depression 86 Groove 87 Notch 88 Groove 89 Groove 90 Groove 93 Groove 94 Groove 95 Thick film part 96 Thin film part 100 Operation monitoring electrode 101 Notch part 102 Terminal part 103 Intermediate electrode

Claims (4)

A lower electrode;
A piezoelectric film provided on the lower electrode,
An upper electrode provided on the piezoelectric film and facing the lower electrode with the piezoelectric film interposed therebetween;
Including
The piezoelectric film,
A columnar tissue layer formed by depositing a piezoelectric material by a sputtering method and having a <100> orientation or a <111>orientation;
Is formed by depositing a piezoelectric material of the columnar texture and the same kind by a sol-gel method, are stacked in contact with the columnar texture, it viewed including the amorphous structure layer of a piezoelectric material,
The piezoelectric film or the upper electrode comprises a starting portion of the displacement of the piezoelectric film, a piezoelectric element. The piezoelectric element according to claim 1, wherein the columnar tissue layer is a layer formed by depositing the piezoelectric material in a polarized state. A seed formation region and a seed non-formation region are set on the surface of the lower electrode,
The columnar tissue layer is formed in the seed formation region, and the columnar tissue layer is not formed in the seed non-formation region,
The amorphous structure layer is formed straddling the seed formation region and the seed non-forming region, the piezoelectric element according to claim 1 or 2. A substrate defining a cavity in which the ink is stored;
A vibrating membrane supported by the substrate and defining the cavity;
Wherein disposed vibrating film, wherein changing the volume of the cavity by displacing the vibrating membrane, and a piezoelectric element according to any one of claims 1 to 3, the ink jet head.

Images