JP2019181963A - Liquid emission device and manufacturing method for liquid emission device - Google Patents

Abstract

To restrict occurrence of crack in a piezoelectric film in the case of deformation of an active part, by providing an end of the active part of the piezoelectric film with a configuration for making discontinuous crystalline of piezoelectric material unlikely to occur.SOLUTION: A head unit comprises: a plurality of pressure chambers 26; an insulation films 30 for covering the plurality of pressure chambers 26; and a plurality of piezoelectric elements 31 arranged on the insulation film 30 and provided in correspondence with the plurality of pressure chambers 26, respectively. Each of the plurality of piezoelectric elements 31 has: a lower electrode 32 disposed on the insulation film 30; a piezoelectric film 33 disposed on the lower electrode 32; and an upper electrode 34 disposed on the piezoelectric film 33. The plurality of upper electrodes 34 conducts with each other via common wiring 42. In a short-side direction of the pressure chambers 26, both ends of the upper electrode 34 are located further on a central side of the pressure chamber 26 from both ends of the lower electrode 32.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a liquid ejection apparatus and a method for manufacturing the liquid ejection apparatus.

  Patent Document 1 discloses an ink jet head that ejects ink from a nozzle as a liquid ejecting apparatus. The ink jet head of Patent Document 1 includes a flow path forming substrate in which a plurality of pressure chambers communicating with nozzles are formed, and a piezoelectric actuator provided on the flow path forming substrate. Each pressure chamber of the flow path forming substrate has a rectangular shape, and the plurality of pressure chambers are arranged along the short direction of each pressure chamber.

  The piezoelectric actuator includes a diaphragm made of silicon dioxide or the like that covers the plurality of pressure chambers, and a plurality of piezoelectric elements provided on the diaphragm corresponding to the plurality of pressure chambers. Each piezoelectric element has a piezoelectric film, a lower electrode located below the piezoelectric film, and an upper electrode located above the piezoelectric film.

  The lower electrode is an individual electrode provided individually for the pressure chamber. The lower electrode is disposed on the diaphragm so as to overlap the central portion of the pressure chamber. On the other hand, the upper electrode is arranged so as to overlap almost the entire pressure chamber. Further, the upper electrodes are electrically connected to each other between the plurality of piezoelectric elements, and the same potential is applied to the plurality of upper electrodes. That is, a common electrode of a plurality of piezoelectric elements is constituted by a plurality of upper electrodes.

  A portion of the piezoelectric film sandwiched between the lower electrode and the upper electrode becomes an active portion (active portion) that is deformed when a voltage is applied between the two electrodes. As described above, since the upper electrode overlaps the entire pressure chamber in the short direction of the pressure chamber, the positions of both ends of the active part are defined by the lower electrode on the lower side.

JP 2014-184603 A

  In Patent Document 1, the lower electrode is disposed on the upper surface of the diaphragm so as to overlap the central portion of the pressure chamber. That is, in the short direction of the pressure chamber, the lower electrode is disposed only in the central region and the lower electrode is not disposed in the end region of the region overlapping the pressure chamber on the upper surface of the diaphragm. Therefore, the piezoelectric film is formed on the lower electrode in the central region of the diaphragm, whereas it is directly formed on the diaphragm in the end region.

  Here, when the piezoelectric film is directly formed on the diaphragm such as silicon dioxide, that is, on the amorphous layer, and when the piezoelectric film is formed on the lower electrode, that is, on the crystal layer. The crystal growth of the piezoelectric material is different. For this reason, the crystal orientation direction is different between the portion formed in the central region and the portion formed in the end region of the piezoelectric film, and the crystallinity tends to be discontinuous between the two. Further, in Patent Document 1, since the position of the end of the active portion is defined by the lower electrode, the portion where the crystallinity is discontinuous matches the position of the end portion of the active portion. Therefore, when a voltage is applied to the piezoelectric element and the active part is deformed, non-uniform distortion occurs at the end of the active part where the crystallinity becomes discontinuous, resulting in cracks, and the element is destroyed. There is a fear.

  An object of the present invention is to realize a configuration in which a portion where the crystallinity of the piezoelectric material is not discontinuous is hardly generated at the end of the active portion, and to suppress the occurrence of cracks in the piezoelectric film when the active portion is deformed.

According to a first aspect of the present invention, there is provided the liquid ejection device, wherein the plurality of pressure chambers having a shape elongated in the first direction, the first insulating film covering the plurality of pressure chambers, the first insulating film, the plurality of the pressure chambers, A plurality of piezoelectric elements respectively corresponding to the pressure chambers,
Each of the plurality of piezoelectric elements includes a lower electrode disposed on the first insulating film, a piezoelectric film disposed on the lower electrode, an upper electrode disposed on the piezoelectric film, The plurality of upper electrodes are electrically connected to each other through a common wiring, and in the second direction orthogonal to the first direction, both ends of the upper electrode are more than the ends of the lower electrode. It is located in the center side of a pressure chamber.

  In the present invention, the lower electrode formed on the first insulating film is an individual electrode provided for each pressure chamber, and a drive signal can be individually supplied to each lower electrode. On the other hand, with respect to the upper electrode, the upper electrodes of the plurality of piezoelectric elements are conducted through the common wiring, and the same potential is applied to the plurality of upper electrodes.

  In the present invention, in the second direction, which is the short direction of the pressure chamber, both ends of the upper electrode are closer to the center of the pressure chamber than both ends of the lower electrode. For this reason, the positions of both ends of the active portion sandwiched between the lower electrode and the upper electrode of the piezoelectric film are defined by the upper electrode. That is, the end position of the lower electrode is not related to the end position of the active part. Therefore, even if a portion where the crystallinity is discontinuous occurs in the piezoelectric film with the end position of the lower electrode as a boundary, the discontinuous portion does not coincide with the end portion of the active portion. Therefore, the occurrence of cracks in the piezoelectric film during the deformation of the active portion is suppressed.

  According to a second aspect of the present invention, there is provided the liquid ejection device according to the first aspect, wherein an inner portion and an end side of the piezoelectric film located on the center side of the pressure chamber with respect to the end of the upper electrode in the second direction. The crystal of the piezoelectric material is preferentially oriented in a predetermined plane orientation in both of the outer portions located in the region.

  According to a third aspect of the present invention, there is provided the liquid ejection device according to the second aspect, wherein an inner portion of the piezoelectric film is located on the center side of the pressure chamber with respect to the end of the upper electrode in the second direction. The crystal of the piezoelectric material is oriented in the (100) plane in both of the outer portions located on the end side.

  In the present invention, the inner part than the end of the upper electrode is included in the active part, and the outer part is a part outside the active part. The crystal of the piezoelectric material is preferentially oriented in a predetermined plane orientation in both the inner part included in the active part and the outer part outside the active part. That is, the crystallinity is continuous at the end of the active part. Therefore, cracks are unlikely to occur in the piezoelectric film when the active part is deformed.

  In the second or third invention, it is preferable that the upper electrode includes a platinum layer (fourth invention). Furthermore, a seed layer may be disposed between the platinum layer and the piezoelectric film of the upper electrode (fifth invention).

  In the liquid ejection device according to a sixth aspect of the present invention, in any one of the first to fifth aspects, in the second direction, both ends of the lower electrode are positioned outside both ends of the pressure chamber. It is characterized by.

  In the present invention, since the lower electrode is formed in the entire area of the pressure chamber in the second direction, a crystalline discontinuous portion is unlikely to occur in the piezoelectric film in the entire area overlapping the pressure chamber.

  According to a seventh aspect of the present invention, there is provided the liquid ejection apparatus according to the sixth aspect, wherein the piezoelectric film has two side surfaces in the second direction.

  When the side surface is formed by patterning the piezoelectric film by etching, the portion of the first insulating film located under the piezoelectric film covering the pressure chamber is also etched in the vicinity of the side surface of the piezoelectric film so that the film thickness is thin. It may become. In this respect, in the present invention, since the lower electrode is formed to the outside of the end of the pressure chamber, the lower electrode can prevent the film loss of the portion covering the pressure chamber of the first insulating film.

  According to an eighth aspect of the invention, in the seventh aspect of the invention, the upper surface of the piezoelectric film exposed from the upper electrode, the two side surfaces of the piezoelectric film in the second direction, and the piezoelectric film of the lower electrode. It has the 2nd insulating film which covers two edge parts exposed from the side surface of a film | membrane, It is characterized by the above-mentioned.

  Since the second insulating film covers from the upper surface to the side surface of the piezoelectric film and further to the end portion of the lower electrode protruding from the piezoelectric film, the insulation between the lower electrodes is improved in addition to the protection of the piezoelectric film.

  According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the liquid ejection apparatus includes a third insulating film that covers a region of the surface of the piezoelectric film where the upper electrode is not disposed. It is a feature.

  In the present invention, in the second direction, the width of the upper electrode is smaller than that of the lower electrode, and a region not covered by the upper electrode exists on the surface of the piezoelectric film. Therefore, a third insulating film is provided in a region of the piezoelectric film that is not covered by the upper electrode. The third insulating film prevents moisture from entering the piezoelectric film from the outside.

  According to a tenth aspect of the present invention, in the ninth aspect, the third insulating film includes an end portion on one side of the first direction of the upper electrode and the first direction of the piezoelectric film. One side surface is covered, and the other end of the third insulating film in the first direction is located closer to the center than the edge of the pressure chamber.

  In the portion overlapping with the edge of the pressure chamber, the deformation shape of the piezoelectric film when the active portion is deformed becomes steep, and cracks are likely to occur in the piezoelectric film. In this regard, in the present invention, the end of the upper electrode in the first direction and the end of the third insulating film covering the side surface of the piezoelectric film are located on the center side of the edge of the pressure chamber. That is, since a part of the third insulating film overlaps with the edge of the pressure chamber, the deformation shape of the piezoelectric film at the edge of the pressure chamber becomes gentle, and cracks are prevented.

  According to an eleventh aspect of the present invention, in the tenth aspect of the invention, the one end of the lower electrode in the first direction is on the one side in the first direction with respect to the side surface of the piezoelectric film. And a first exposed portion in which the lower electrode is exposed from the piezoelectric film, and an individual wiring electrically connected to the lower electrode through the first exposed portion. Is.

  In the present invention, the end of the lower electrode extends in the second direction and is exposed from the piezoelectric film. The individual wiring is electrically connected to the lower electrode through the first exposed portion of the lower electrode.

  In a liquid ejection apparatus according to a twelfth aspect according to the eleventh aspect, the lower electrode is disposed at a wide portion overlapping a central portion of the pressure chamber, and on the one side in the first direction with respect to the wide portion. And a narrow portion having a width in the second direction smaller than the wide portion, and the other end of the third insulating film is connected to the wide portion of the lower electrode and the upper electrode. It is located in the center side of the said pressure chamber rather than the edge of the area | region which opposes.

  In the present invention, the end of the third insulating film is located closer to the center of the pressure chamber than the end of the region where the wide portion of the lower electrode and the upper electrode face each other. That is, the third insulating film overlaps with the main part of the active part of the piezoelectric film.

  According to a thirteenth aspect of the present invention, in the eleventh or twelfth aspect, the liquid ejection device is disposed between the third insulating film and the piezoelectric film, and is formed of the same material as the upper electrode. A conductive film disposed over an upper surface of the piezoelectric film, a side surface of the piezoelectric film, and an upper surface of the first exposed portion; and the conductive film is formed on the third insulating film on the first exposed portion. And the individual wiring is overlapped with the second exposed portion and the first exposed portion.

  In the present invention, the conductive film is formed from the side surface of the piezoelectric film to the first exposed portion of the lower electrode. By leaving the conductive film covering the first exposed portion during the patterning of the upper electrode, the first exposed portion is prevented from being removed together by the etching during the patterning.

  The conductive film is covered with a third insulating film. However, if the conductive film is entirely covered by the third insulating film up to the tip, a part of the first exposed portion located at the tip of the conductive film is directly covered by the third insulating film. In this case, when the individual wiring is superimposed on the first exposed portion, a part of the first exposed portion does not come into contact with the conductive film and the individual wiring. In particular, when the lower electrode is thin, there is a possibility that disconnection may occur in a part of the first exposed portion. In this regard, in the present invention, the conductive film is not entirely covered with the third insulating film, but the end portion of the conductive film is exposed from the third insulating film to become the second exposed portion. The reliability of the electrical connection is improved by overlapping the individual wiring from the second exposed portion of the conductive film to the first exposed portion of the lower electrode.

  According to a fourteenth aspect of the present invention, in any one of the first to thirteenth aspects, the common wiring is electrically connected in common to the plurality of upper electrodes and is thicker than the upper electrode. It has one common wiring.

  Since the plurality of upper electrodes are connected by the thick first common wiring, the electric resistance of the common wiring is lowered. Therefore, potential variations among the plurality of upper electrodes can be suppressed.

  According to a fifteenth aspect of the invention, in any one of the first to fourteenth aspects, the common wiring is formed of the same material as the plurality of upper electrodes in the same layer as the plurality of upper electrodes. In addition, the second common wiring is electrically connected in common to the plurality of upper electrodes.

  Since the second common wiring connecting the plurality of upper electrodes is arranged in the same layer as the upper electrode, the second common wiring can be formed by the same process as the upper electrode.

  According to a sixteenth aspect of the present invention, in the fourteenth or fifteenth aspect, the common wiring has an overlapping portion that overlaps an end portion of the pressure chamber in the first direction. .

  Since the common wiring overlaps the end portion of the pressure chamber in the first direction at the overlapping portion, the device size in the first direction can be reduced.

  According to a seventeenth aspect of the present invention, in the sixteenth aspect, the plurality of pressure chambers are arranged in the second direction, the common wiring extends in the second direction, and the plurality of upper electrodes Conductive wiring is provided, and at least a part of the conductive wiring overlaps the plurality of pressure chambers to form the overlapping portion.

  In the present invention, the plurality of upper electrodes are electrically connected by the conductive wiring extending in the second direction of the common wiring. Moreover, this conduction | electrical_connection wiring becomes the duplication part which overlaps with the edge part of a some pressure chamber.

  According to an eighteenth aspect of the invention, in the sixteenth or seventeenth aspect of the invention, the overlapping portion overlaps the end portion of the lower electrode in the first direction. is there.

  In the present invention, the overlapping portion of the common wiring that overlaps the end of the pressure chamber further overlaps the end of the lower electrode.

  A liquid ejection device according to a nineteenth aspect of the present invention includes the fourth insulating film according to any one of the sixteenth to eighteenth aspects, wherein the fourth insulating film covers a region of the surface of the piezoelectric film where the upper electrode is not disposed. The fourth insulating film is also disposed between the overlapping portion and the piezoelectric film.

  In the present invention, the fourth insulating film is disposed between the overlapping portion and the piezoelectric film. That is, the fourth insulating film overlaps the end portion of the pressure chamber in the first direction. Thereby, the deformation | transformation shape of a piezoelectric film in the edge part of a pressure chamber becomes loose, and a crack is suppressed.

  According to a twentieth aspect of the invention, in the nineteenth aspect of the invention, an end of the lower electrode on the overlapping portion side in the first direction overlaps the fourth insulating film. Is.

  In the present invention, the fourth insulating film that overlaps the end portion of the pressure chamber in the first direction may further overlap the end portion of the lower electrode.

  According to a twenty-first aspect of the present invention, there is provided a method for manufacturing a liquid ejection apparatus comprising: an insulating film forming step for forming an insulating film on a substrate on which a plurality of pressure chambers having a long shape in the first direction is formed; A lower electrode forming step for forming an electrode, a piezoelectric film forming step for forming a piezoelectric film on the lower electrode, an upper electrode forming step for forming an upper electrode on the piezoelectric film, and a plurality of upper electrodes in conduction A common wiring forming step for forming a common wiring to be formed, wherein, in the lower electrode forming step and the upper electrode forming step, both ends of the upper electrode are in the lower direction in a second direction orthogonal to the first direction. The lower electrode and the upper electrode are formed so as to be located closer to the center side of the pressure chamber than both ends of the electrode.

  In the present invention, the lower electrode and the upper electrode are formed so that both ends of the upper electrode are positioned more centrally than both ends of the lower electrode in the second direction, which is the short direction of the pressure chamber. For this reason, the positions of both ends of the active portion sandwiched between the lower electrode and the upper electrode of the piezoelectric film are defined by the upper electrode. That is, the end position of the lower electrode is not related to the end position of the active part. Therefore, when the piezoelectric film is formed on the lower electrode, even if the crystallinity of the piezoelectric film becomes discontinuous with the end position of the lower electrode as a boundary, the discontinuous portion is separated from the end of the active portion. Does not match. Therefore, the occurrence of cracks in the piezoelectric film during the deformation of the active portion is suppressed.

1 is a schematic plan view of a printer according to an embodiment. It is a top view of a head unit. It is the A section enlarged view of FIG. It is the figure which abbreviate | omitted illustration of the insulating film, the separate wiring, and the thick film wiring in FIG. It is the VV sectional view taken on the line of FIG. It is the VI-VI sectional view taken on the line of FIG. It is a figure which shows the manufacturing process of a head unit, (a) is insulating film formation, (b) is lower electrode formation, (c) is piezoelectric film formation, (d) is upper electrode formation, (e) is piezoelectricity The formation of an insulating film for film protection is shown. It is a figure which shows the manufacturing process of a head unit, (a) shows pressure chamber formation, (b) shows nozzle plate joining. It is sectional drawing equivalent to FIG. 6 of the head unit of a change form. It is sectional drawing equivalent to FIG. 6 of the head unit of another modification. It is sectional drawing equivalent to FIG. 5 of the head unit of another modification. It is sectional drawing equivalent to FIG. 5 of the head unit of another modification. It is sectional drawing equivalent to FIG. 5 of the head unit of another modification.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic plan view of a printer according to the present embodiment. First, a schematic configuration of the inkjet printer 1 will be described with reference to FIG. 1 are defined as “front”, “rear”, “left”, and “right” of the printer. Also, the front side of the page is defined as “up”, and the other side of the page is defined as “down”. Below, it demonstrates using each direction word of front, back, left, right, up and down suitably.

(Schematic configuration of the printer)
As shown in FIG. 1, the inkjet printer 1 includes a platen 2, a carriage 3, an inkjet head 4, a transport mechanism 5, a control device 6, and the like.

  On the upper surface of the platen 2, a recording sheet 100 as a recording medium is placed. The carriage 3 is configured to be capable of reciprocating in the left-right direction (hereinafter also referred to as the scanning direction) along the two guide rails 10 and 11 in a region facing the platen 2. An endless belt 14 is connected to the carriage 3, and the endless belt 14 is driven by a carriage drive motor 15, whereby the carriage 3 moves in the scanning direction.

  The inkjet head 4 is attached to the carriage 3 and moves in the scanning direction together with the carriage 3. The ink jet head 4 includes four head units 16 arranged in the scanning direction. The four head units 16 are respectively connected to a cartridge holder 7 to which ink cartridges 17 of four colors (black, yellow, cyan, magenta) are mounted by tubes (not shown). Each head unit 16 has a plurality of nozzles 24 (see FIGS. 2 to 6) formed on the lower surface thereof (the surface on the opposite side of the paper surface of FIG. 1). The nozzles 24 of each head unit 16 discharge the ink supplied from the ink cartridge 17 toward the recording paper 100 placed on the platen 2.

  The transport mechanism 5 includes two transport rollers 18 and 19 disposed so as to sandwich the platen 2 in the front-rear direction. The transport mechanism 5 transports the recording paper 100 placed on the platen 2 forward (hereinafter also referred to as a transport direction) by two transport rollers 18 and 19.

The control device 6 includes a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit) including various control circuits, and the like. The control device 6 executes various processes such as printing on the recording paper 100 by the ASIC according to the program stored in the ROM. For example, in the printing process, the control device 6 controls the inkjet head 4, the carriage drive motor 15, and the like based on a print command input from an external device such as a PC, and prints an image or the like on the recording paper 100. . Specifically, an ink discharge operation for discharging ink while moving the inkjet head 4 in the scanning direction together with the carriage 3 and a transport operation for transporting the recording paper 100 in the transport direction by the transport rollers 18 and 19 alternately. Let me do it.

(Details of inkjet head)
Next, the configuration of the head unit 16 of the inkjet head 4 will be described in detail. Since the four head units 16 have the same configuration, only one of the four head units 16 will be described below.

  FIG. 2 is a plan view of the head unit 16. FIG. 3 is an enlarged view of a portion A in FIG. FIG. 4 is a diagram in which the insulating film 40, the individual wiring 41, and the thick film wiring 44 are not shown in FIG. 5 is a cross-sectional view taken along line VV in FIG. 3, and FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. As shown in FIGS. 2 to 6, the head unit 16 includes a nozzle plate 20, a flow path substrate 21, a piezoelectric actuator 22, a COF 50 (Chip On Film), a cover member 23, and the like. For simplification of the drawing, FIG. 2 does not show the cover member 23 and the COF 50 arranged on the flow path substrate 21 shown in FIG. In FIG. 3, the COF 50 is schematically shown by a two-dot chain line.

(Nozzle plate)
The nozzle plate 20 is a plate formed of, for example, silicon. A plurality of nozzles 24 are formed on the nozzle plate 20. As shown in FIG. 2, the plurality of nozzles 24 constitutes two nozzle rows 27 arranged in the transport direction and arranged in the scanning direction. Further, when the arrangement pitch of the nozzles 24 in one nozzle row 27 is P, the position of the nozzle 24 is shifted by P / 2 in the transport direction between the two nozzle rows 27.

(Channel substrate)
The flow path substrate 21 is a silicon single crystal substrate. A plurality of pressure chambers 26 communicating with the plurality of nozzles 24 are formed in the flow path substrate 21. Each pressure chamber 26 has a rectangular planar shape that is long in the scanning direction. The plurality of pressure chambers 26 are arranged according to the arrangement of the plurality of nozzles 24 described above, and constitute two pressure chamber rows 28 arranged in the scanning direction. The lower surface of the flow path substrate 21 is covered with the nozzle plate 20, and the inner end in the scanning direction of each pressure chamber 26 overlaps the nozzle 24 when viewed from the vertical direction.

  As shown in FIG. 2, two manifolds 25 extending in the transport direction are formed at the left and right ends of the flow path substrate 21 corresponding to the two pressure chamber rows 28, respectively. As shown in FIGS. 3 to 5, each of the pressure chambers 26 constituting one pressure chamber row 28 is connected to a corresponding manifold 25 by a throttle channel 29 extending in the scanning direction.

  The manifold 25 is open on the upper surface of the flow path substrate 21. The opening of the manifold 25 is connected to the cartridge holder 7 by an ink supply member (not shown) including a tube and the like. The ink in the ink cartridge 17 of the cartridge holder 7 flows into the manifold 25 through the ink supply member, and is further supplied from the manifold 25 to the pressure chambers 26 through the throttle channel 29.

(Piezoelectric actuator)
The piezoelectric actuator 22 is a laminated body of a plurality of films including an insulating film 30, a plurality of piezoelectric elements 31, an insulating film 40 for protecting the piezoelectric elements 31, individual wirings 41, and a common wiring 42. The piezoelectric actuator 22 is disposed on the flow path substrate 21 so as to cover the plurality of pressure chambers 26.

<Insulating film 30>
The insulating film 30 is, for example, a silicon dioxide film formed by oxidizing the surface of the silicon flow path substrate 21. The thickness of the insulating film 30 is, for example, 1.0 to 1.5 μm. A plurality of piezoelectric elements 31 are arranged on the upper surface of the insulating film 30 at positions overlapping the plurality of pressure chambers 26, respectively. The piezoelectric element 31 imparts ejection energy for ejecting from the nozzle 24 to the ink in the pressure chamber 26.

<Piezoelectric element 31>
The configuration of the piezoelectric element 31 will be described. Each of the plurality of piezoelectric elements 31 includes a lower electrode 32 disposed on the insulating film 30, a piezoelectric film 33 disposed on the lower electrode 32, and an upper electrode 34 disposed on the piezoelectric film 33. Have.

  The lower electrode 32 is disposed in a region overlapping the pressure chamber 26 on the upper surface of the insulating film 30. The lower electrode 32 is a so-called individual electrode to which a drive signal is individually supplied from a driver IC 51 to be described later via the individual wiring 41. In the configuration in which the lower electrode 32 on the insulating film 30 is an individual electrode, wiring for supplying a drive signal to the lower electrode 32 can be formed on the flat insulating film 30, so that wiring can be easily formed. Thus, there is an advantage that disconnection or the like hardly occurs.

  The lower electrode 32 has a rectangular wide portion 32a that is long in the scanning direction, and a narrow portion 32b that is disposed on the inner side in the scanning direction than the wide portion 32a. As shown in FIGS. 3 and 5, the wide portion 32 a is disposed so as to overlap the central portion of the pressure chamber 26 in the scanning direction that is the longitudinal direction of the pressure chamber 26. As shown in FIGS. 3 and 6, both ends of the wide portion 32 a are located outside the both ends of the pressure chamber 26 in the transport direction, which is the short direction of the pressure chamber 26. That is, the wide portion 32 a partially protrudes outward from the edge of the pressure chamber 26. On the other hand, as shown in FIG. 3, the narrow portion 32b has a smaller width in the transport direction than the wide portion 32a. The narrow portion 32b is drawn from the inner end portion (right end portion in FIG. 3) in the scanning direction of the wide portion 32a and extends to a region between the two pressure chamber rows 28. The lower electrode 32 is made of, for example, platinum (Pt). The thickness of the lower electrode 32 is, for example, 0.1 μm.

  The piezoelectric film 33 is formed of a piezoelectric material such as lead zirconate titanate (PZT). The piezoelectric film 33 may be formed of a lead-free piezoelectric material that does not contain lead in addition to PZT. The thickness of the piezoelectric film 33 is, for example, 1.0 to 2.0 μm. Specifically, as shown in FIGS. 2 and 3, in the present embodiment, the piezoelectric films 33 of the plurality of piezoelectric elements 31 are connected in the transport direction, and a rectangular piezoelectric body 37 that is long in the transport direction is configured. Yes. That is, on the insulating film 30, two piezoelectric bodies 37 made of the piezoelectric films 33 corresponding to the two pressure chamber rows 28 are arranged.

  As shown in FIG. 5, the narrow portion 32 b of the lower electrode 32 is exposed from the side surface 33 a on the inner side (right side in FIG. 5) in the scanning direction of the piezoelectric film 33 and extends further inward. Through the first exposed portion 32c of the narrow portion 32b, the lower electrode 32 is connected to an individual wiring 41 described later.

  As shown in FIGS. 2 to 4 and 6, a slit 38 extending in the scanning direction is formed in a portion of one piezoelectric body 37 between the plurality of pressure chambers 26. The slit 38 divides the piezoelectric film 33 between two pressure chambers 26 adjacent in the transport direction. Thereby, as shown in FIG. 6, the part of the piezoelectric film 33 corresponding to one pressure chamber 26 has two side surfaces 33b in the transport direction. Both ends of the lower electrode 32 in the transport direction are located outside the both ends of the pressure chamber 26 and are outside the two side surfaces 33 b of the piezoelectric film 33.

  The upper electrode 34 is disposed in a region overlapping the pressure chamber 26 on the upper surface of the piezoelectric film 33. Similar to the wide portion 32a of the lower electrode 32, the upper electrode 34 has a rectangular planar shape that is long in the scanning direction. The upper electrode 34 is made of, for example, iridium. The thickness of the upper electrode 34 is, for example, 0.1 μm.

  As shown in FIGS. 3 and 6, the width of the upper electrode 34 is smaller than the width of the lower electrode 32 in the transport direction, which is the short direction of the pressure chamber 26. Further, both ends of the upper electrode 34 are located closer to the center of the pressure chamber 26 than both ends of the lower electrode 32. The upper electrodes 34 of the plurality of piezoelectric elements 31 are electrically connected to each other by a common wiring 42 described later, and a ground potential is applied to the plurality of upper electrodes 34 in common.

  The piezoelectric film 33 of each piezoelectric element 31 is sandwiched between the lower electrode 32 and the upper electrode 34 in a region facing the pressure chamber 26. A portion of the piezoelectric film 33 sandwiched between the lower electrode 32 and the upper electrode 34 is hereinafter referred to as an active portion 36. In each piezoelectric element 31, when a potential difference is generated between the lower electrode 32 and the upper electrode 34 and an electric field in the thickness direction acts on the active portion 36, the active portion 36 is deformed in the surface direction. As the active portion 36 is deformed, the piezoelectric element 31 is deformed so as to be bent as a whole, and the portion facing the pressure chamber 26 is displaced in the vertical direction perpendicular to the surface direction of the insulating film 30.

  As described above, in the present embodiment, as shown in FIG. 6, both ends of the upper electrode 34 in the transport direction are located closer to the center of the pressure chamber 26 than both ends of the lower electrode 32. That is, the positions of both ends of the active portion 36 in the transport direction are defined by the positions of both ends of the upper electrode 34. Therefore, both the inner portion 33 x located on the center side of the pressure chamber 26 and the outer portion 33 y located on the end side of the piezoelectric film 33 are formed on the lower electrode 32 with respect to the end of the upper electrode 34. The Thereby, the crystal of the piezoelectric material is preferentially oriented in a predetermined plane orientation, specifically, the (100) plane in both the inner portion 33x included in the active portion 36 and the outer portion 33y outside the active portion 36. That is, there is no portion where the crystallinity is discontinuous at the end of the active portion 36. Therefore, the occurrence of cracks in the piezoelectric film 33 during the deformation of the active portion 36 is suppressed. Here, the preferential orientation in the (100) plane is not only the form in which all the crystals of the piezoelectric film 33 are oriented in the (100) plane, but 90% or more of the crystals are oriented in the (100) plane. The form is also included.

  In order to preferentially orient the piezoelectric film 33 in a predetermined plane orientation, the lower electrode 32 is preferably formed of platinum (Pt). Platinum is a material with strong self-orientation and self-orientates into a face-centered cubic lattice (FCC) structure, which is a close-packed structure. Therefore, the platinum layer of the lower electrode 32 exhibits strong orientation regardless of the state of the base. For example, even if the platinum layer is formed on the insulating film 30 that is an amorphous silicon dioxide layer, the platinum layer is oriented in a predetermined plane orientation. Accordingly, the piezoelectric film 33 formed on the lower electrode 32 having the aligned crystal directions also exhibits a strong orientation. A seed layer for crystal control of the piezoelectric film 33 may be provided between the lower electrode 32 and the piezoelectric film 33. As the seed layer, an appropriate material can be selected from known materials such as titanium oxide, lead titanate, PZT, and the like.

  In particular, in this embodiment, both ends of the lower electrode 32 are positioned outside both ends of the pressure chamber 26 in the transport direction, and the lower electrode 32 is formed over the entire region of the pressure chamber 26 in the transport direction. Accordingly, a discontinuous portion of crystallinity hardly occurs in the entire region of the piezoelectric film 33 that overlaps the pressure chamber 26.

  In addition, as will be described later, in this embodiment, after the piezoelectric film 33 is formed over the entire upper surface of the insulating film 30, the film 33 is patterned by etching. Here, when the side surface 33b of the piezoelectric film 33 is formed by etching, the portion of the insulating film 30 located under the piezoelectric film 33 and covering the pressure chamber 26 is slightly etched in the vicinity of the side surface 33b. The film thickness may become thin. In this regard, when the lower electrode 32 is formed to the outside of both ends of the pressure chamber 26, the lower electrode 32 can prevent the film from being reduced in the portion of the insulating film 30 that covers the pressure chamber 26.

  Further, both ends of the lower electrode 32 protrude from the two side surfaces 33b of the piezoelectric film 33, respectively. In other words, the entire piezoelectric film 33 is disposed on the lower electrode 32 in the transport direction, and it can be said that the discontinuous portion is hardly generated in the piezoelectric film 33 in the first place.

  As shown in FIG. 5, a conductive film 39 made of the same material (for example, iridium) as the upper electrode 34 is provided at the end of the piezoelectric film 33 on the first exposed portion 32 c side of the lower electrode 32. Yes. The conductive film 39 is disposed from the upper surface of the piezoelectric film 33 to the side surface 33a of the piezoelectric film 33 and the upper surface of the first exposed portion 32c. The conductive film 39 is formed when the upper electrode 34 is patterned. As will be described later, the upper electrode 34 is formed by forming a conductive film over the entire surface of the piezoelectric film 33 and then patterning the film by etching. During this patterning, the conductive film 39 covering the first exposed portion 32c is intentionally left, thereby preventing the underlying first exposed portion 32c from being etched.

<Insulating film 40>
Incidentally, as described above, in the present embodiment, the width of the upper electrode 34 is smaller than the width of the lower electrode 32. Therefore, a region that is not covered with the upper electrode 34 exists on the surface of the piezoelectric film 33. Therefore, an insulating film 40 for protecting the piezoelectric film 33 is provided in a region of the surface of the piezoelectric film 33 that is not covered by the upper electrode 34. The insulating film 40 prevents moisture from entering the piezoelectric film 33 from the outside.

  Specifically, first, as shown in FIGS. 3 and 5, the insulating film 40 is slightly overlapped with the peripheral edge of the upper electrode 34 on the upper surface of the piezoelectric film 33 of each piezoelectric element 31. It is arranged in the surrounding area. In other words, the central portion of the upper electrode 34 is exposed from the insulating film 40 on the upper surface of the piezoelectric film 33. As a result, the deformation of the active portion 36 is not easily inhibited by the insulating film 40. The insulating film 40 covers the side surface 33 a in the scanning direction and the side surface 33 b in the transport direction from the upper surface of the piezoelectric film 33.

  Further, as shown in FIG. 5, the insulating film 40 also covers the conductive film 39 at the inner end portion (right end portion in FIG. 5) of the piezoelectric film 33 in the scanning direction. However, on the first exposed portion 32 c, the leading end portion of the conductive film 39 is not covered with the insulating film 40, and is a second exposed portion 39 a exposed from the insulating film 40.

  Further, in the portion overlapping the edge of the pressure chamber 26, the deformed shape of the piezoelectric film 33 when the active portion 36 is deformed becomes steep, and the piezoelectric film 33 is likely to crack. In this regard, in the present embodiment, as shown in FIG. 5, the insulating film 40 is formed on the inner end (right side in FIG. 5) of the piezoelectric film 33 in the scanning direction. In addition, the end E1 (left end in FIG. 5) of the insulating film 40 is located closer to the center than the edge of the pressure chamber 26. That is, when the insulating film 40 overlaps the edge of the pressure chamber 26, the deformed shape of the piezoelectric film 33 at the edge becomes gentle, and cracks are prevented. Further, the end E1 of the insulating film 40 is located closer to the center of the pressure chamber 26 than the end of the region B where the wide portion 32a of the lower electrode 32 and the upper electrode 34 face each other. That is, since the insulating film 40 also overlaps with the main part of the active part 36, cracks in the piezoelectric film 33 are further suppressed.

  Further, as shown in FIG. 6, in the transport direction, the insulating film 40 extends from the upper surface of the piezoelectric film 33 to the upper surface of the insulating film 40 via the side surface 33b. That is, the insulating film 40 covers the two end portions of the lower electrode 32 exposed from the two side surfaces 33 b of the piezoelectric film 33. Thus, since the insulating film 40 covers from the upper surface of the piezoelectric film 33 to the side surface 33b and further to the end portion of the lower electrode 32 protruding from the piezoelectric film 33, in addition to protecting the piezoelectric film 33, the lower electrode The insulation between 32 is also improved.

<Individual wiring 41>
As shown in FIG. 5, the individual wiring 41 is disposed so as to overlap the first exposed portion 32c of the lower electrode 32, and is electrically connected to the lower electrode 32 via the first exposed portion 32c. The individual wiring 41 is made of, for example, gold (Au). The individual wiring 41 is thicker than the lower electrode 32 and is, for example, 1.0 μm.

  As described above, the leading end portion of the conductive film 39 is the second exposed portion 39 a exposed from the insulating film 40. The end portion of the individual wiring 41 is overlapped with the first exposed portion 32 c of the lower electrode 32 and the second exposed portion 39 a of the conductive film 39 exposed from the insulating film 40.

  Here, suppose that the conductive film 39 is entirely covered by the insulating film 40 up to the tip thereof, as shown by the phantom line in FIG. 5, the first exposed portion 32 c positioned before the conductive film 39. A part is directly covered by the insulating film 40. In this case, when the individual wiring 41 is superimposed on the first exposed portion 32 c, a part of the first exposed portion 32 c directly covered with the insulating film 40 does not come into contact with the conductive film 39 and the individual wiring 41. . In particular, when the lower electrode 32 is thin, there is a possibility that disconnection may occur in a part of the first exposed portion 32c. However, in this embodiment, the tip of the conductive film 39 is exposed from the insulating film 40. Therefore, the individual wiring 41 is overlapped from the second exposed portion 39a of the conductive film 39 to the first exposed portion 32c of the lower electrode 32, and the reliability of electrical connection is improved.

  The individual wiring 41 extends to the region between the two pressure chamber rows 28 along the first exposed portion 32 c of the lower electrode 32. A driving contact 46 is formed at the end of the individual wiring 41 opposite to the lower electrode 32. Between the two pressure chamber rows 28, the drive contact 46 of the individual wiring 41 extending from the left piezoelectric element 31 and the drive contact 46 of the individual wiring 41 extending from the right piezoelectric element 31 are alternately arranged in the transport direction. It has been.

<Common wiring 42>
The common wiring 42 includes a thin film wiring 43 and a thick film wiring 44 which are arranged in different layers and are both electrically connected to the plurality of upper electrodes 34 in common.

  As shown in FIGS. 3 and 5, the thin film wiring 43 extends in the transport direction in an outer region in the scanning direction of the upper surface of the piezoelectric body 37. By this thin film wiring 43, the outer end portions (left end portions in FIG. 5) of the plurality of upper electrodes 34 arranged in the transport direction are electrically connected to each other. The thin film wiring 43 is formed in the same layer as the upper electrode 34 by using the same material (for example, iridium) as the plurality of upper electrodes 34. Therefore, as will be described later, the thin film wiring 43 can be simultaneously formed by the patterning process of the upper electrode 34.

  The thick film wiring 44 is formed on the insulating film 40. As shown in FIG. 2, the thick film wiring 44 is disposed on the upper surface of the piezoelectric body 37 so as to surround the plurality of upper electrodes 34 arranged in the transport direction. The outer end portions (left end portions in FIG. 5) of the plurality of upper electrodes 34 are electrically connected to each other by the outer portion of the thick film wiring 44 in the scanning direction, and the inner end portions (see FIG. 5 are connected to each other. The thick film wiring 44 is formed of the same material (for example, gold) as the individual wiring 41. The thickness of the thick film wiring 44 is thicker than that of the upper electrode 34, for example, 1.0 μm. Since the plurality of upper electrodes 34 are conducted by the thick film wiring 44, the electric resistance of the common wiring 42 is lowered. Therefore, potential variations among the plurality of upper electrodes 34 can be suppressed.

  The thick film wiring 44 of the individual wiring 41 and the common wiring 42 may be formed of a material other than gold such as aluminum. However, when the wiring is formed of aluminum, it is preferably covered with a wiring protective film formed of SiN or the like.

  As shown in FIGS. 2 and 3, the first conductive wiring 45 a that connects the outer end portions of the plurality of upper electrodes 34 to each other is constituted by the thin film wiring 43 and the outer portion of the thick film wiring 44 in the scanning direction. Has been. In addition, the inner portion of the thick film wiring 44 in the scanning direction constitutes a second conductive wiring 45 b that connects the inner ends of the plurality of upper electrodes 34 to each other.

  Furthermore, the common wiring 42 has an overlapping portion that overlaps the end portions of the plurality of pressure chambers 26 in the scanning direction. Specifically, as shown in FIGS. 3 and 5, a part of the first conductive wiring 45a on the outer side in the scanning direction overlaps with the outer end portions of the plurality of pressure chambers 26, and the second conductive wiring 45b on the inner side in the scanning direction. Is overlapped with the inner ends of the plurality of pressure chambers 26. In addition, the first conductive wiring 45 a and the second conductive wiring 45 b as overlapping portions also overlap with the end portion of the lower electrode 32 in the scanning direction. As described above, since the common wiring 42 overlaps the end of the pressure chamber 26 in the scanning direction, the size of the head unit 16 in the scanning direction can be reduced.

  The insulating film 40 is disposed between the first conductive wiring 45 a and the second conductive wiring 45 b as overlapping portions and the piezoelectric film 33. That is, the insulating film 40 overlaps the edge of the pressure chamber 26 in the scanning direction. Therefore, the deformed shape of the piezoelectric film 33 at the edge of the pressure chamber 26 becomes gentle, and cracks in the piezoelectric film 33 are suppressed. Furthermore, since the insulating film 40 also overlaps with the end portion of the lower electrode 32, cracks are further suppressed.

  As shown in FIG. 2, the common wiring 42 has two lead wirings 48 that conduct the second conductive wiring 45 b on the upper surfaces of the two left and right piezoelectric bodies 37. The two lead wires 48 are respectively arranged on the front side and the rear side of the plurality of drive contacts 46 in the region between the two pressure chamber rows 28. A central portion in the scanning direction of each lead-out wiring 48 is a ground contact 47 to which a COF 50 described later is joined.

(COF)
As shown in FIGS. 2 to 5, one end of the COF 50 is joined to the central portion in the scanning direction of the flow path substrate 21 where the plurality of drive contacts 46 and the two ground contacts 47 are arranged. A driver IC 51 is mounted in the middle of the COF 50. The other end of the COF 50 is connected to the control device 6 (see FIG. 1) of the printer 1. In the COF 50, a plurality of input lines 53, a plurality of output lines 52, and ground lines (not shown) connected to the driver IC are formed. The driver IC 51 is electrically connected to the control device 6 via the input wiring 53. Further, when the COF 50 is bonded to the flow path substrate 21, the ends of the plurality of output wirings 52 are electrically connected to the plurality of driving contacts 46, respectively. The ground wiring of the COF 50 is electrically connected to the ground contact 47.

  The driver IC 51 generates a drive signal based on the control signal from the control device 6 and outputs it to each piezoelectric element 31. The drive signal is input to the drive contact 46 via the output wiring 52 and further supplied to the corresponding lower electrode 32 via the individual wiring 41. At this time, the potential of the lower electrode 32 changes between a predetermined drive potential and the ground potential. On the other hand, the ground potential is commonly applied to the plurality of upper electrodes 34 connected to the ground contact 47 by the common wiring 42.

  The operation of each piezoelectric element 31 when a drive signal is supplied from the driver IC 51 will be described. When no drive signal is input, the potential of the lower electrode 32 is the ground potential and the same potential as the upper electrode 34. When a drive signal is input to the lower electrode 32 from this state, an electric field in the thickness direction acts on the active portion 36 of the piezoelectric film 33 due to a potential difference with the upper electrode 34. At this time, the active part 36 on the insulating film 30 is deformed and bent so that one whole piezoelectric element 31 is convex toward the pressure chamber 26 side. As a result, the volume of the pressure chamber 26 is reduced, a pressure wave is generated in the pressure chamber 26, and ink droplets are ejected from the nozzles 24 communicating with the pressure chamber 26.

(Cover member)
The cover member 23 protects the plurality of piezoelectric elements 31 and is bonded to the upper surface of the insulating film 30 with an adhesive. As shown in FIGS. 2 and 5, the cover member 23 includes an opening 23 a formed at the center in the scanning direction and two covers 23 b provided on both the left and right sides of the opening 23 a. The COF 50 joined to the drive contacts 46 and the two ground contacts 47 is passed through the opening 23a. The two left and right cover portions 23b cover the two piezoelectric bodies 37, respectively. Note that the openings of the manifolds 25 respectively formed at the left and right ends of the flow path substrate 21 are exposed from the cover member 23 so as to be connectable to an ink supply member (not shown).

  Next, the manufacturing process of the head unit 16 described above will be described. First, FIG. 7 is a diagram showing a manufacturing process of the piezoelectric actuator 22, FIG. 7A is the formation of the insulating film 30, (b) is the formation of the lower electrode 32, and (c) is the formation of the piezoelectric film 33. (D) shows the formation of the upper electrode 34, and (e) shows the formation of the insulating film 40 for protecting the piezoelectric film.

  First, as shown in FIG. 7A, a silicon dioxide insulating film 30 is formed on the surface of a silicon flow path substrate 21 by thermal oxidation or the like.

  Next, as shown in FIG. 7B, a film of platinum (Pt) or the like is formed on the insulating film 30 by sputtering or the like, and is patterned to form a plurality of lower electrodes 32. At this time, patterning of the lower electrode 32 is performed so that both ends of the lower electrode 32 in the transport direction protrude beyond the region C where the pressure chambers 26 of the flow path substrate 21 are formed.

  Next, as shown in FIG. 7C, a piezoelectric film 33 is formed on the plurality of lower electrodes 32 by a sol-gel method, sputtering, or the like by a piezoelectric material such as PZT over the entire upper surface of the insulating film 30. The film 33 is patterned by etching to form a piezoelectric body 37.

  Here, in the transport direction, both ends of the lower electrode 32 are located outside the two side surfaces of the piezoelectric film 33. That is, the entire piezoelectric film 33 is disposed on the lower electrode 32, and the conditions of the surface on which the piezoelectric film 33 is formed are equal in the transport direction. Therefore, in the transport direction, the crystal orientation direction of the piezoelectric material constituting the piezoelectric film 33 is made uniform, and a portion where the crystallinity is discontinuous does not occur.

  Further, since the lower electrode 32 is formed to the outside of the end of the pressure chamber forming region C of the insulating film 30, when the piezoelectric film 33 is patterned, the lower electrode 32 causes the pressure of the insulating film 30 to be increased. It is possible to prevent the film from being reduced in the portion covering the chamber 26.

  Next, as shown in FIG. 7D, a film of iridium (Ir) or the like is formed on the upper surface of the piezoelectric film 33 by sputtering or the like, and this film is patterned to form a plurality of upper electrodes 34. . At this time, the upper electrode 34 is formed so that both ends of the upper electrode 34 in the transport direction are located closer to the center of the pressure chamber 26 than both ends of the lower electrode 32. Thereby, the positions of both ends of the active portion 36 are defined by the positions of the upper electrode 34 in the transport direction. Further, as described above, the crystal orientation of the piezoelectric film 33 disposed on the lower electrode 32 is uniform. Therefore, a portion where the crystallinity is discontinuous does not occur at the end of the active portion 36.

  In the patterning of the upper electrode 34, by leaving the conductive film 39 (see FIG. 5) covering from the upper surface of the piezoelectric film 33 to the first exposed portion 32c of the lower electrode 32 through the side surface 33a, The first exposed portion 32c of the lower electrode 32 is prevented from being etched. In addition, a thin film wiring 43 (see FIGS. 3 and 5) of the common wiring 42 for conducting the plurality of upper electrodes 34 is formed at the same time as the above patterning.

  Next, as shown in FIG. 7E, an insulating film 40 is formed on the upper electrode 34, and the insulating film 40 is patterned. Although not shown in FIG. 7, the individual wiring 41 and the thick film wiring 44 (see FIG. 5) of the common wiring 42 are formed on the insulating film 40 with gold (Au) or the like.

  8A shows the formation of the pressure chamber 26, and FIG. 8B shows the joining of the nozzle plate 20. FIG. After the piezoelectric actuator 22 is formed, a cover member 23 (see FIG. 5) is joined to the flow path substrate 21, and then a process such as polishing of the flow path substrate 21 is performed. Thereafter, as shown in FIG. 8A, etching is performed from the lower surface of the flow path substrate 21 opposite to the piezoelectric actuator 22 to form a plurality of pressure chambers 26 in the flow path substrate 21. Further, as shown in FIG. 8B, the nozzle plate 20 is joined to the lower surface of the flow path substrate 21 opposite to the piezoelectric actuator 22.

  In the embodiment described above, the scanning direction which is the longitudinal direction of the pressure chamber 26 corresponds to the “first direction” of the present invention, and the transport direction which is the short direction of the pressure chamber 26 is the “second direction” of the present invention. Corresponds to "direction". The head unit 16 corresponds to the “liquid ejecting apparatus” of the invention. The insulating film 30 corresponds to the “first insulating film” of the present invention. The insulating film 40 corresponds to the “second insulating film”, “third insulating film”, and “fourth insulating film” of the present invention. The thick film wiring 44 corresponds to the “first common wiring” of the present invention, and the thin film wiring 43 corresponds to the “second common wiring” of the present invention.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

1] On the assumption that the positions of both ends of the upper electrode 34 in the transport direction are closer to the center side of the pressure chamber 26 than both ends of the lower electrode 32, the following changes may be made.

  For example, as shown in FIG. 9A, the positions of both ends of the lower electrode 32 may be positioned closer to the center of the pressure chamber 26 than both ends of the piezoelectric film 33. Alternatively, as shown in FIG. 9B, the positions of both ends of the lower electrode 32 may be positioned closer to the center of the pressure chamber 26 than both ends of the pressure chamber 26.

  9A and 9B, since both ends of the lower electrode 32 are closer to the center side than both ends of the piezoelectric film 33, a portion of the piezoelectric film 33 above the lower electrode 32 and In some cases, the crystallinity may be discontinuous between the outer portion and the outer portion. However, since both ends of the upper electrode 34 are located closer to the center than both ends of the lower electrode 32, the end position of the active portion 36 is defined by the end position of the upper electrode 34. Does not matter. That is, even if the crystallinity of the piezoelectric film 33 becomes discontinuous with the end position of the lower electrode 32 as a boundary, the discontinuous portion does not coincide with the end portion of the active portion 36. Therefore, the occurrence of cracks in the piezoelectric film 33 during the deformation of the active portion 36 is suppressed.

2] In the above embodiment, as shown in FIG. 6, the piezoelectric film 33 is divided by the slit 38 between the two pressure chambers 26 arranged in the transport direction. On the other hand, as shown in FIG. 10, the slits 38 are not formed, and the piezoelectric film 33 may be continuous between the pressure chambers 26 adjacent to each other in the transport direction.

3] In the above embodiment, the conductive film 39 is disposed on the side surface 33b of the piezoelectric film 33 where the lower electrode 32 is exposed. However, the conductive film 39 may be omitted.

4] The formation position of the insulating film 40 covering the piezoelectric film 33 can be changed as appropriate. For example, in the embodiment, as shown in FIG. 5, the insulating film 40 overlaps with the edge of the pressure chamber 26 and further overlaps with the active portion 36 in the scanning direction. On the other hand, the insulating film 40 may not overlap with the active portion 36. Further, the insulating film 40 may be formed only in a region outside the edge of the pressure chamber 26 and may not overlap the edge of the pressure chamber 26.

  Further, as shown in FIG. 11, the right end portion of the insulating film 40 may not cover the conductive film 39. Alternatively, as illustrated in FIG. 12, the insulating film 40 between the conductive film 39 and the thick film wiring 44 may be removed after the insulating film 40 covers the conductive film 39.

5] The configuration of the common wiring 42 can be changed as appropriate. For example, as shown in FIG. 13, the left portion of the thick film wiring 44 in FIG. 13 is in contact with the plurality of upper electrodes 34 or the thin film wirings 43 in the region outside the plurality of pressure chambers 26 in the scanning direction. Also good. In addition, the common wiring 42 does not need to be composed of two types of wirings 43 and 44 located in different layers, and the wiring of one of the layers may be omitted. Further, it is not essential that the common wiring 42 overlaps the end portions in the scanning direction of the plurality of pressure chambers 26, and the common wiring 42 may not overlap the pressure chamber 26.

  In the embodiment described above, the present invention is applied to an ink jet head that prints an image or the like by ejecting ink onto a recording sheet. However, the liquid ejecting apparatus is used for various purposes other than printing an image or the like. The present invention can also be applied. For example, the present invention can also be applied to a liquid ejection apparatus that ejects a conductive liquid onto a substrate to form a conductive pattern on the surface of the substrate.

16 Head unit 21 Channel substrate 26 Pressure chamber 30 Insulating film 31 Piezoelectric element 32 Lower electrode 32a Wide portion 32b Narrow portion 32c First exposed portion 33 Piezoelectric film 33a Side surface 33b Side surface 33x Inner portion 33y Outer portion 34 Upper electrode 36 Active portion 39 Conductive film 39a Second exposed portion 40 Insulating film 41 Individual wiring 42 Common wiring 43 Thin film wiring 44 Thick film wiring 45a First conductive wiring 45b Second conductive wiring

Claims (21)

A plurality of pressure chambers arranged in a first direction;
A first insulating film covering the plurality of pressure chambers;
A plurality of piezoelectric elements disposed on the first insulating film and provided respectively corresponding to the plurality of pressure chambers;
Each of the plurality of piezoelectric elements is
A lower electrode disposed on the first insulating film;
A piezoelectric film disposed on the lower electrode;
An upper electrode disposed on the piezoelectric film,
The plurality of upper electrodes are electrically connected to each other through a common wiring,
In the second direction orthogonal to the first direction, both ends of the upper electrode are located closer to the center of the pressure chamber than both ends of the lower electrode.   With respect to the end of the upper electrode in the second direction of the piezoelectric film, the crystal of the piezoelectric material has a predetermined surface in both the inner portion located on the center side of the pressure chamber and the outer portion located on the end side. The liquid discharge apparatus according to claim 1, wherein the liquid discharge apparatus is preferentially oriented in the direction.   With respect to the end of the upper electrode in the second direction of the piezoelectric film, crystals of the piezoelectric material are (100) in both the inner part located on the center side of the pressure chamber and the outer part located on the end side. The liquid ejection device according to claim 2, wherein the liquid ejection device is oriented in a plane.   The liquid ejecting apparatus according to claim 2, wherein the upper electrode includes a platinum layer.   The liquid ejection apparatus according to claim 4, wherein a seed layer is disposed between the platinum layer of the upper electrode and the piezoelectric film.   6. The liquid ejection apparatus according to claim 1, wherein in the second direction, both ends of the lower electrode are positioned outside both ends of the pressure chamber.   The liquid ejection apparatus according to claim 6, wherein the piezoelectric film has two side surfaces in the second direction.   A second insulation covering an upper surface of the piezoelectric film exposed from the upper electrode, two side surfaces of the piezoelectric film in the second direction, and two ends exposed from the side surfaces of the piezoelectric film of the lower electrode; The liquid ejection apparatus according to claim 7, further comprising a film.   The liquid ejection apparatus according to claim 1, further comprising a third insulating film that covers a region of the surface of the piezoelectric film where the upper electrode is not disposed. The third insulating film covers an end of the upper electrode on one side in the first direction and a side surface of the piezoelectric film on the one side in the first direction;
The liquid ejecting apparatus according to claim 9, wherein an end of the third insulating film on the other side in the first direction is located closer to a center side than an edge of the pressure chamber. An end of the lower electrode on the one side in the first direction is drawn to the one side in the first direction from a side surface of the piezoelectric film, and the first electrode is exposed from the piezoelectric film. An exposed portion;
The liquid ejecting apparatus according to claim 10, further comprising: an individual wiring electrically connected to the lower electrode through the first exposed portion. The lower electrode has a wide portion that overlaps a central portion of the pressure chamber, a width that is disposed on the one side in the first direction with respect to the wide portion, and has a width that is smaller in the second direction than the wide portion. With a narrow portion,
The other end of the third insulating film is located closer to the center of the pressure chamber than an end of a region where the wide portion of the lower electrode and the upper electrode are opposed to each other. The liquid ejection apparatus according to claim 11. It is disposed between the third insulating film and the piezoelectric film and is formed of the same material as the upper electrode, and further includes an upper surface of the piezoelectric film, a side surface of the piezoelectric film, and the first exposed portion. Having a conductive film disposed over the top surface;
The conductive film has a second exposed portion exposed from the third insulating film on the first exposed portion,
The liquid ejecting apparatus according to claim 11, wherein the individual wiring is overlapped with the second exposed portion and the first exposed portion.   The liquid ejection according to claim 1, wherein the common wiring includes a first common wiring that is electrically connected in common to the plurality of upper electrodes and is thicker than the upper electrode. apparatus.   The common wiring includes a second common wiring that is formed of the same material as the plurality of upper electrodes in the same layer as the plurality of upper electrodes and is electrically connected to the plurality of upper electrodes in common. The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is a liquid ejection apparatus.   The liquid ejecting apparatus according to claim 14, wherein the common wiring has an overlapping portion that overlaps an end portion of the pressure chamber in the first direction. The plurality of pressure chambers are arranged in the second direction,
The common wiring extends in the second direction and includes a conductive wiring that is electrically connected to the plurality of upper electrodes,
The liquid ejecting apparatus according to claim 16, wherein at least a part of the conductive wiring overlaps the plurality of pressure chambers to form the overlapping portion.   18. The liquid ejection apparatus according to claim 16, wherein the overlapping portion overlaps with an end portion of the lower electrode in the first direction. A fourth insulating film covering a region of the surface of the piezoelectric film where the upper electrode is not disposed;
The liquid ejecting apparatus according to claim 16, wherein the fourth insulating film is also disposed between the overlapping portion and the piezoelectric film.   20. The liquid ejection apparatus according to claim 19, wherein an end of the lower electrode on the overlapping portion side in the first direction and the fourth insulating film overlap each other. An insulating film forming step of forming an insulating film on a substrate on which a plurality of pressure chambers arranged in the first direction are formed;
A lower electrode forming step of forming a lower electrode on the insulating film;
A piezoelectric film forming step of forming a piezoelectric film on the lower electrode;
An upper electrode forming step of forming an upper electrode on the piezoelectric film;
A common wiring forming step of forming a common wiring for conducting a plurality of upper electrodes,
In the lower electrode forming step and the upper electrode forming step,
In the second direction orthogonal to the first direction, the lower electrode and the upper electrode are formed so that both ends of the upper electrode are located closer to the center side of the pressure chamber than both ends of the lower electrode. A method for manufacturing a liquid ejection device.

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