JP2016185601A - Inkjet head and inkjet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head capable of suppressing cracks or the like in piezoelectric layers, and further to provide an ink jet printer.SOLUTION: An ink jet head comprises: a pressure chamber formation substrate 29 where a plurality of pressure chambers 30 is formed; diaphragms 31 partitioning surfaces of one sides of the plurality of pressure chambers 30 and allowing deformation of partitioned regions 35; piezoelectric elements constituted by sequentially laminating lower electrode layers 37, piezoelectric layers 38 and an upper electrode layer 39 from surfaces of opposite sides of the diaphragms 31 to pressure chamber 30 sides; and a sealing plate 33 disposed so as to be spaced from the diaphragms 31 in a state where a plurality of bump electrodes 42 is interposed between the diaphragms 31 and the sealing plate 33. Ends of the upper electrode layer 39 are extended outside of ends of the partitioned regions 35, and ends of the lower electrode layers 37 and ends of the piezoelectric layers 38 are extended outside of the ends of the upper electrode layer 39. The bump electrodes 42 electrically connected to the upper electrode layer 39 are formed across from positions overlapping with the upper electrode layer 39 to positions facing the piezoelectric layers 38 outside of the ends of the upper electrode layer 39.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an inkjet head including a piezoelectric element that is deformed by application of a voltage, and an inkjet printer including the inkjet head.

  An ink jet printer is a device that includes a permanent head and ejects (discharges) various liquids from the permanent head. An ink jet printer is a non-impact printing apparatus in which characters are formed on a paper by jetting ink particles or droplets (JIS X0012-1990). This is a form of a dot printer that is a printer that prints characters and images expressed by a plurality of points, and prints characters and images expressed by a plurality of points formed by jetting ink particles or droplets. A permanent head is a mechanical part or an electrical part of a printer body that generates ink droplets continuously or intermittently (hereinafter referred to as “inkjet head”). JIS Z8123-1: 2013). In addition to being used as an image recording apparatus, this ink jet printer is also applied to various manufacturing apparatuses taking advantage of the fact that a very small amount of liquid can be landed accurately at a predetermined position. For example, a display manufacturing apparatus for manufacturing a color filter such as a liquid crystal display, an electrode forming apparatus for forming an electrode such as an organic EL (Electro Luminescence) display or FED (surface emitting display), a chip for manufacturing a biochip (biochemical element) Applied to manufacturing equipment.

  The ink jet head is configured to cause a pressure fluctuation in the liquid in the pressure chamber by driving the piezoelectric element, and to eject the liquid from the nozzle using the pressure fluctuation. As this piezoelectric element, for example, in order from the side closer to the pressure chamber, a lower electrode layer that functions as a common electrode common to a plurality of pressure chambers, a piezoelectric layer such as lead zirconate titanate (PZT), and a pressure chamber An upper electrode layer functioning as an individual electrode provided for each layer is formed by being laminated by a film forming technique (for example, Patent Document 1). The lower electrode layer and the upper electrode layer are routed outward from the piezoelectric layer on the substrate and connected to a flexible cable, a drive circuit (also referred to as a driver circuit), or the like. When a voltage is applied to the lower electrode layer and the upper electrode layer via these flexible cables, the piezoelectric layer sandwiched between both electrode layers is deformed. That is, both electrode layers and the portion sandwiched between them function as a piezoelectric element that causes pressure fluctuation in the pressure chamber.

Japanese Patent Laid-Open No. 2002-292781

  By the way, when the piezoelectric element is deformed, the stress accompanying the deformation is present at the boundary between the portion of the piezoelectric layer not sandwiched between the electrode layers and the portion sandwiched between the electrode layers and functioning as the piezoelectric element. Occur. This stress may cause cracks or the like in the piezoelectric layer.

  This invention is made | formed in view of such a situation, The objective is to provide the inkjet head which can suppress the crack of a piezoelectric material layer, etc., and an inkjet printer.

An inkjet head of the present invention has been proposed to achieve the above-described object, and a pressure chamber forming substrate in which a plurality of pressure chambers communicating with a nozzle are formed along a first direction;
A diaphragm that divides a surface on one side of the pressure chamber, and allows deformation of the partitioned region;
In a region corresponding to the pressure chamber, a piezoelectric element in which a first electrode layer, a piezoelectric layer, and a second electrode layer are stacked in order from the surface opposite to the pressure chamber side of the diaphragm;
A circuit board that outputs a signal that drives the piezoelectric element, and is arranged with a gap to the diaphragm in a state where a plurality of bump electrodes are interposed between the diaphragm and the diaphragm,
In a second direction orthogonal to the first direction, one end of the second electrode layer is extended to the outside from one end of the partition region, and one end of the first electrode layer An end on one side and an end on one side of the piezoelectric layer are extended to the outside from an end on one side of the second electrode layer,
The bump electrode that is electrically connected to the second electrode layer extends from a position that overlaps the second electrode layer to a position that faces the piezoelectric layer outside the one end of the second electrode layer. It is characterized by being formed.

  According to this configuration, a part of the bump electrode that is electrically connected to the second electrode layer faces the piezoelectric layer, so that when the piezoelectric layer is deformed, the end of the second electrode layer is Concentration of stress on the piezoelectric layer at the position can be suppressed. That is, the electric field generated in the piezoelectric layer sandwiched between the first electrode layer and the second electrode layer is weaker than the electric field generated in the piezoelectric layer sandwiched between the first electrode layer and the bump electrode. Since an electric field is generated, it is possible to suppress the occurrence of stress accompanying rapid deformation in the piezoelectric layer at the end of the second electrode layer. Thereby, a boundary (second second) between a portion not sandwiched between the first electrode layer and the second electrode layer and a portion sandwiched between the first electrode layer and the second electrode layer. It is possible to suppress the occurrence of cracks or the like in the piezoelectric layer at the end of the electrode layer.

  In the above structure, the dimension of the bump electrode electrically connected to the second electrode layer in the first direction is in a region overlapping the bump electrode electrically connected to the second electrode layer. It is desirable that the dimension of the first electrode layer is larger than the dimension in the first direction.

  According to this configuration, even when the bump electrode is displaced in the first direction due to a manufacturing error or the like, the area of the region where the bump electrode and the first electrode layer overlap is hardly changed. Thereby, an electric field can be more reliably generated between the first electrode layer and the bump electrode. As a result, it is possible to more reliably suppress the occurrence of cracks or the like in the piezoelectric layer at the end position of the second electrode layer.

  Furthermore, in each of the above configurations, it is desirable that an adhesive be provided between a portion of the bump electrode facing the piezoelectric layer and the piezoelectric layer.

  According to this configuration, the voltage applied between the bump electrode and the first electrode layer can be divided into the adhesive and the piezoelectric layer. Therefore, an electric field weaker than that of the piezoelectric layer sandwiched between the first electrode layer and the second electrode layer is more reliably generated in the piezoelectric layer facing the bump electrode via the adhesive. Can do. The piezoelectric layer at the boundary between the portion not sandwiched between the first electrode layer and the second electrode layer and the portion sandwiched between the first electrode layer and the second electrode layer Can be suppressed by an adhesive. By this. It is possible to further suppress the occurrence of cracks or the like in the piezoelectric layer at this boundary.

  An ink jet printer according to the present invention includes the ink jet head having the above-described configuration.

FIG. 3 is a perspective view illustrating a configuration of a printer. FIG. 3 is a cross-sectional view illustrating a configuration of a recording head. It is sectional drawing explaining the structure of an actuator unit. It is a top view explaining the structure of an actuator unit. It is sectional drawing to which the principal part of the actuator unit was expanded. It is sectional drawing explaining the structure of the actuator unit in 2nd Embodiment. It is sectional drawing explaining the structure of the actuator unit in 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following description, as an ink jet printer of the present invention, a printer 1 equipped with a recording head 3 which is a kind of ink jet head will be described as an example.

  The configuration of the printer 1 will be described with reference to FIG. The printer 1 is an apparatus that records an image or the like by ejecting ink (a type of liquid) onto the surface of a recording medium 2 (a type of landing target) such as a recording paper. The printer 1 includes a recording head 3, a carriage 4 to which the recording head 3 is attached, a carriage moving mechanism 5 that moves the carriage 4 in the main scanning direction, a conveyance mechanism 6 that transfers the recording medium 2 in the sub scanning direction, and the like. Yes. Here, the ink is stored in an ink cartridge 7 as a liquid supply source. The ink cartridge 7 is detachably attached to the recording head 3. It is also possible to employ a configuration in which the ink cartridge is disposed on the main body side of the printer and supplied from the ink cartridge to the recording head through the ink supply tube.

  The carriage moving mechanism 5 includes a timing belt 8. The timing belt 8 is driven by a pulse motor 9 such as a DC motor. Therefore, when the pulse motor 9 operates, the carriage 4 is guided by the guide rod 10 installed on the printer 1 and reciprocates in the main scanning direction (width direction of the recording medium 2). The position of the carriage 4 in the main scanning direction is detected by a linear encoder (not shown) which is a kind of position information detecting means. The linear encoder transmits the detection signal, that is, the encoder pulse (a kind of position information) to the control unit of the printer 1.

  In addition, a home position serving as a base point for scanning of the carriage 4 is set in an end area outside the recording area within the movement range of the carriage 4. In this home position, a cap 11 for sealing the nozzle 22 formed on the nozzle surface (nozzle plate 21) of the recording head 3 and a wiping unit 12 for wiping the nozzle surface are arranged in this order from the end side. Has been.

  Next, the recording head 3 will be described. FIG. 2 is a cross-sectional view illustrating the configuration of the recording head 3. FIG. 3 is an enlarged cross-sectional view of the main part of the recording head 3, that is, a cross-sectional view of the actuator unit 14. FIG. 4 is an enlarged plan view of a main part (left end part in FIG. 3) of the actuator unit 14. FIG. 5 is an enlarged cross-sectional view of a main part of the actuator unit 14. As shown in FIG. 2, the recording head 3 in this embodiment is attached to the head case 16 in a state where the actuator unit 14 and the flow path unit 15 are stacked. In FIG. 4, other components are omitted in order to facilitate understanding of the positional relationship among the piezoelectric element 32, the pressure chamber 30, the bump electrode 42, and the like. For convenience, the stacking direction of each member constituting the actuator unit 14 will be described as the vertical direction.

  The head case 16 is a box-shaped member made of synthetic resin, and a reservoir 18 for supplying ink to each pressure chamber 30 is formed therein. The reservoir 18 is a space for storing ink common to a plurality of formed pressure chambers 30, and two reservoirs 18 are formed corresponding to the rows of the pressure chambers 30 arranged in parallel (rows). . An ink introduction path (not shown) for introducing ink from the ink cartridge 7 side into the reservoir 18 is formed above the head case 16. An accommodation space 17 that is recessed in a rectangular parallelepiped shape from the lower surface to the middle of the height direction of the head case 16 is formed on the lower surface side of the head case 16. When a flow path unit 15 to be described later is joined in a state of being positioned on the lower surface of the head case 16, the actuator unit 14 (the pressure chamber forming substrate 29, the sealing plate 33, etc.) stacked on the communication substrate 24 is accommodated in the accommodation space. 17 is configured to be accommodated in the interior.

  The flow path unit 15 joined to the lower surface of the head case 16 has a communication substrate 24 and a nozzle plate 21. The communication substrate 24 is a plate made of silicon, and in this embodiment, is formed from a silicon single crystal substrate whose surface (upper surface and lower surface) is a (110) surface. As shown in FIG. 2, the communication substrate 24 communicates with the reservoir 18 and stores a common liquid chamber 25 in which ink common to the pressure chambers 30 is stored, and the reservoir 18 through the common liquid chamber 25. Individual communication passages 26 for individually supplying ink to the pressure chambers 30 are formed by etching. The common liquid chambers 25 are long empty portions along the direction in which the pressure chambers 30 are arranged side by side (first direction x, see FIG. 4), and are formed in two rows corresponding to the two reservoirs 18. The common liquid chamber 25 is depressed halfway in the thickness direction of the communication substrate 24 from the first liquid chamber 25a penetrating the thickness direction of the communication substrate 24 and from the lower surface side to the upper surface side of the communication substrate 24. And a second liquid chamber 25b formed with the thin plate portion left on the upper surface side. A plurality of individual communication passages 26 are formed along the direction in which the pressure chambers 30 are arranged in correspondence with the pressure chambers 30 in the thin plate portion of the second liquid chamber 25b. The individual communication passage 26 communicates with an end portion on one side in the longitudinal direction of the corresponding pressure chamber 30 in a state where the communication substrate 24 and the pressure chamber forming substrate 29 are positioned and joined.

  In addition, nozzle communication passages 27 that penetrate the thickness direction of the communication substrate 24 are formed at positions corresponding to the respective nozzles 22 of the communication substrate 24. That is, a plurality of nozzle communication paths 27 are formed along the nozzle row direction corresponding to the nozzle rows. The pressure chamber 30 and the nozzle 22 communicate with each other through the nozzle communication path 27. The nozzle communication path 27 of the present embodiment is a state in which the communication substrate 24 and the pressure chamber forming substrate 29 are positioned and joined, and the corresponding pressure chamber 30 is moved in the longitudinal direction (second direction orthogonal to the first direction x). It communicates with the end portion on the other side (the side opposite to the individual communication path 26) in the direction y (see FIG. 4).

  The nozzle plate 21 is a silicon substrate (for example, a silicon single crystal substrate) bonded to the lower surface of the communication substrate 24 (the surface opposite to the pressure chamber forming substrate 29). In this embodiment, the nozzle plate 21 seals the opening on the lower surface side of the space serving as the common liquid chamber 25. The nozzle plate 21 has a plurality of nozzles 22 arranged in a straight line (row shape). In the present embodiment, two rows of nozzle rows are formed corresponding to the rows of pressure chambers 30 formed in two rows. The plurality of nozzles 22 (nozzle rows) arranged side by side have a pitch (for example, 600 dpi) corresponding to the dot formation density from the nozzle 22 on one end side to the nozzle 22 on the other end side, and in the sub-scanning direction orthogonal to the main scanning direction. Are provided at regular intervals. In addition, the nozzle plate may be joined to a region of the communication substrate that is inward from the common liquid chamber, and the opening on the lower surface side of the space that becomes the common liquid chamber may be sealed with a member such as a flexible compliance sheet. it can. In this way, the nozzle plate can be made as small as possible.

  As shown in FIGS. 2 and 3, the actuator unit 14 is unitized by stacking a pressure chamber forming substrate 29, a vibration plate 31, a piezoelectric element 32, and a sealing plate 33. The actuator unit 14 is formed smaller than the accommodation space 17 so as to be accommodated in the accommodation space 17.

  The pressure chamber forming substrate 29 is a hard plate material made of silicon, and in this embodiment, the pressure chamber forming substrate 29 is made of a silicon single crystal substrate whose surface (upper surface and lower surface) is a (110) surface. A part of the pressure chamber forming substrate 29 is completely removed in the plate thickness direction by etching, and a plurality of spaces to be the pressure chambers 30 are formed along the first direction x. This space is partitioned by the communication substrate 24 on the lower side and partitioned by the diaphragm 31 to constitute the pressure chamber 30. In addition, this space, that is, the pressure chamber 30 is formed in two rows corresponding to the nozzle rows formed in two rows. Each pressure chamber 30 is a hollow portion that is long in a second direction y orthogonal to the first direction x (that is, the nozzle row direction), and the second direction y (that is, the longitudinal direction of the pressure chamber 30). The individual communication passage 26 communicates with one end of the nozzle), and the nozzle communication passage 27 communicates with the other end. Note that both side walls in the second direction y of the pressure chamber 30 of this embodiment are inclined with respect to the upper surface or the lower surface of the pressure chamber forming substrate 29 due to the crystallinity of the silicon single crystal substrate.

The diaphragm 31 is a thin film member having elasticity, and is laminated on the upper surface of the pressure chamber forming substrate 29 (surface opposite to the communication substrate 24). The diaphragm 31 seals the upper opening of the space to be the pressure chamber 30. In other words, the upper surface of the pressure chamber 30 is partitioned by the diaphragm 31. A partition region 35 that partitions the upper surface of the pressure chamber 30 in the diaphragm 31 functions as a displacement portion that deforms (displaces) in a direction away from or in the direction of approaching the nozzle 22 as the piezoelectric element 32 is bent and deformed. That is, the partition area 35 in the diaphragm 31 is an area where bending deformation is allowed, and the area outside the partition area 35 in the diaphragm 31 is an area where bending deformation is inhibited. The diaphragm 31 is, for example, an elastic film made of silicon dioxide (SiO ₂ ) formed on the upper surface of the pressure chamber forming substrate 29 and an insulator made of zirconium oxide (ZrO ₂ ) formed on the elastic film. And a membrane. And the piezoelectric element 32 is laminated | stacked in the position corresponding to the division area | region 35 on this insulating film (surface on the opposite side to the pressure chamber 30 side of the diaphragm 31), respectively.

  The piezoelectric element 32 of the present embodiment is a so-called flexure mode piezoelectric element. The piezoelectric elements 32 are arranged in two rows corresponding to the rows of pressure chambers 30 arranged in two rows. As shown in FIG. 3, each piezoelectric element 32 has a lower electrode layer 37 (corresponding to the first electrode layer in the present invention), a piezoelectric layer 38, and an upper electrode layer 39 (first electrode in the present invention) on the diaphragm 31. 2 and the metal layer 40 are sequentially laminated. In this embodiment, the lower electrode layer 37 is an individual electrode formed independently for each piezoelectric element 32, and the upper electrode layer 39 is a common electrode formed continuously across the plurality of piezoelectric elements 32. It has become. That is, as shown in FIG. 4, the lower electrode layer 37 and the piezoelectric layer 38 are formed for each pressure chamber 30. On the other hand, the upper electrode layer 39 is formed across the plurality of pressure chambers 30.

  Specifically, as shown in FIG. 4, the piezoelectric layer 38 in the present embodiment has a width narrower than the width of the partition region 35 (pressure chamber 30) (the dimension in the first direction x). It extends along the direction y. The piezoelectric layers 38 are arranged in two rows corresponding to the rows of pressure chambers 30 arranged in two rows. As shown in FIG. 3, both ends of the piezoelectric layer 38 in the second direction y are extended from a position overlapping the pressure chamber 30 to a position deviating from the position. That is, the end on one side (the outer side in the actuator unit 14) in the second direction y of the piezoelectric layer 38 extends to the outer side than the end of the partition region 35 on the same side. Further, the end of the piezoelectric layer 38 on the other side (inner side in the actuator unit 14) in the second direction y extends to the outside of the end of the partition region 35 on the same side.

  In addition, the lower electrode layer 37 in the present embodiment extends along the second direction y with a width narrower than the width of the partition region 35, similarly to the piezoelectric layer 38. In the present embodiment, as shown in FIG. 4, the width of the lower electrode layer 37 extending outward from the position overlapping the end of the partition region 35 is smaller than that of the other portion of the lower electrode layer 37 overlapping the partition region 35. Is also narrowly formed. In other words, the width at the end of the lower electrode layer 37 is narrower than the width at the center. The width He at the end of the lower electrode layer 37 is narrower than the width Hb of the common bump electrode 42a described later. Furthermore, the lower electrode layers 37 are arranged in two rows corresponding to the rows of pressure chambers 30 arranged in two rows. One end of the lower electrode layer 37 in the second direction y (outside of the actuator unit 14) extends to the outside of the end of the piezoelectric layer 38 on the same side as shown in FIGS. Individual metal layers 40c described later are laminated. Further, the end of the lower electrode layer 37 on the other side (inner side in the actuator unit 14) in the second direction y is a region overlapping with the piezoelectric layer 38 as shown in FIG. It extends to the outside from the end. That is, the other end of the lower electrode layer 37 in the second direction y extends to a region between the end of the partition region 35 and the end of the piezoelectric layer 38.

  Furthermore, the upper electrode layer 39 in the present embodiment extends in the first direction x to the outside of the region overlapping with the group of pressure chambers 30 arranged at both ends. That is, the upper electrode layer 39 is formed across the plurality of piezoelectric layers 38 arranged in parallel in the first direction x. Further, as shown in FIG. 3, the upper electrode layer 39 is formed across the piezoelectric layers 38 on both sides in the second direction y. Specifically, one end (the left side in FIG. 3) of the upper electrode layer 39 in the second direction y is one of the piezoelectric layers 38 arranged in two rows (the left side in FIG. 3). The region overlaps the body layer 38 and extends to the outside of the region overlapping one partition region 35. That is, one end of the upper electrode layer 39 in the second direction y extends to a region between the outer end of one partition region 35 and the outer end of one piezoelectric layer 38. . Further, the other end (right side in FIG. 3) of the upper electrode layer 39 in the second direction y is the other (right side in FIG. 3) piezoelectric layer 38 of the piezoelectric layers 38 arranged in two rows. That extends to the outside of the region that overlaps the other partition region 35. In other words, the other end of the upper electrode layer 39 in the second direction y extends to a region between the outer end of the other partition region 35 and the outer end of the other piezoelectric layer 38. .

  A region where all of the lower electrode layer 37, the piezoelectric layer 38 and the upper electrode layer 39 are laminated, in other words, a region where the piezoelectric layer 38 is sandwiched between the lower electrode layer 37 and the upper electrode layer 39, It functions as the piezoelectric element 32. That is, when an electric field corresponding to the potential difference between the two electrodes is applied between the lower electrode layer 37 and the upper electrode layer 39, the piezoelectric layer 38 bends and deforms in a direction away from or close to the nozzle 22, and the partition region The 35 diaphragms 31 are deformed. As described above, in the second direction y, one end of the upper electrode layer 39 extends to the outside from one end of the partition region 35, and one end of the lower electrode layer 37 and the piezoelectric layer. Since one end of 38 extends outward from one end of the upper electrode layer 39, the position of the element end 34 a on one side of the piezoelectric element 32 is defined by the upper electrode layer 39. That is, the piezoelectric layer 38 extends to the outside of the upper electrode layer 39 in a region deviated from the position overlapping the partition region 35 to one side in the second direction y (outside of the actuator unit 14), and the lower electrode layer 37. Is extended further to the outside of the piezoelectric layer 38, so that the position of the end of the upper electrode layer 39 is the position of the element end 34a on one side of the piezoelectric element 32. On the other hand, the piezoelectric layer 38 extends to the outside of the lower electrode layer 37 in the region deviated from the position overlapping the partition region 35 to the other side in the second direction y (inside in the actuator unit 14), and the upper electrode layer 39. Is extended to the outer side of the piezoelectric layer 38, so that the position of the other end of the lower electrode layer 37 is the position of the element end 34b on the other side of the piezoelectric element 32. Thus, the element ends 34 on both sides of the piezoelectric element 32 in the present embodiment are formed outside the partition region 35 in the second direction y. A portion of the piezoelectric element 32 extending to the outside of the partition region 35 is inhibited from being deformed (displaced) by the pressure chamber forming substrate 29.

  Further, the piezoelectric element 32 in the present embodiment is provided with the metal layers 40 at both ends in the longitudinal direction (second direction y). The metal layer 40 formed at the other end of the piezoelectric element 32 is a first common metal layer 40 a that is stacked on the upper electrode layer 39 and serves as a common electrode. In the second direction y, the first common metal layer 40 a extends from a region overlapping the other end of the partition region 35 to the outside of the region overlapping the piezoelectric layer 38. Further, both ends of the first common metal layer 40a in the first direction x are extended to the outside of a region overlapping with the group of pressure chambers 30 arranged in parallel, as with the upper electrode layer 39. By the first common metal layer 40a, deformation of the element end 34b on the other side of the piezoelectric element 32 and the end on the other side of the partition region 35 is suppressed.

  The metal layer 40 formed on one end of the piezoelectric element 32 is laminated on the upper electrode layer 39, and is a second common metal layer 40b that serves as a common electrode, like the first common metal layer 40a. is there. In the second direction y, the second common metal layer 40b extends from a region overlapping with one end of the partition region 35 to the same end of the upper electrode layer 39 (that is, the element end 34a). ing. Further, both ends of the second common metal layer 40b in the first direction x are extended to the outside of a region overlapping with the group of pressure chambers 30 arranged side by side, like the first common metal layer 40a. . By the second common metal layer 40b, deformation of the element end 34a on one side of the piezoelectric element 32 and the end on one side of the partition region 35 is suppressed. A common bump electrode 42a, which will be described later, is connected on the first common metal layer 40a.

  Further, an individual metal layer 40c that is partially laminated on the lower electrode layer 37 and serves as an individual electrode is formed outside the one end of the piezoelectric element 32 in the second direction y. As shown in FIG. 4, the individual metal layer 40 c is formed to have a width wider than the width at the end of the lower electrode layer 37, and a plurality of the individual metal layers 40 c are formed along the first direction x. In the second direction y, the individual metal layer 40c in this embodiment is a region that is out of the one end of the upper electrode layer 39 and overlaps the one end of the piezoelectric layer 38. It extends to a region that overlaps with one end of the lower electrode layer 37 beyond. An individual bump electrode 42b described later is connected on the individual metal layer 40c.

The lower electrode layer 37 and the upper electrode layer 39 are iridium (Ir), platinum (Pt), titanium (Ti), tungsten (W), nickel (Ni), palladium (Pd), gold (Au). And various metals such as these, alloys thereof, and alloys such as LaNiO ₃ are used. As the piezoelectric layer 38, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), niobium (Nb), nickel (Ni), magnesium (Mg), bismuth (Bi) or yttrium is used. A relaxor ferroelectric or the like to which a metal such as (Y) is added is used. In addition, non-lead materials such as barium titanate can also be used. Further, as the metal layer 40, gold (Au), copper (Cu), etc. on an adhesion layer made of titanium (Ti), nickel (Ni), chromium (Cr), tungsten (W), and alloys thereof. Are used.

  The sealing plate 33 (corresponding to a circuit board in the present invention) is a flat plate-like member disposed with a space from the diaphragm 31 (or the piezoelectric element 32) with a plurality of bump electrodes 42 interposed therebetween. It is. This interval is set to such an extent that the deformation of the piezoelectric element 32 is not hindered. The sealing plate 33 of the present embodiment is composed of a silicon single crystal substrate whose surface (upper surface and lower surface) is a (110) plane, and is aligned with the outer diameter of the pressure chamber forming substrate 29 in plan view. As shown in FIG. 3, a drive circuit 46 (driver circuit) for outputting a signal (drive signal) for individually driving each piezoelectric element 32 is formed in a region of the sealing plate 33 facing the piezoelectric element 32. ing. The drive circuit 46 is formed on the surface of a silicon single crystal substrate (silicon wafer) to be the sealing plate 33 by using a semiconductor process (that is, a film forming process, a photolithography process, an etching process, etc.).

  Further, in the region of the sealing plate 33 that is out of the partition region 35 and that faces the first common metal layer 40a and the individual metal layer 40c formed on the piezoelectric layer 38, a pressure chamber forming substrate is provided. A bump electrode 42 having elasticity and protruding toward the side 29 is formed. The bump electrode 42 includes an elastic internal resin 43 and a conductive film 44 that is electrically connected to a corresponding wiring in the drive circuit 46 and covers the surface of the internal resin 43. In the present embodiment, the individual bump electrodes 42b connected to the individual metal layers 40c of the piezoelectric elements 32 formed in two rows are formed in two rows. In addition, common bump electrodes 42a connected to the second common metal layer 40b of the piezoelectric elements 32 formed in two rows are formed in two rows. As the internal resin 43, for example, a resin such as a polyimide resin is used. The conductive film 44 is made of a metal such as gold (Au), copper (Cu), nickel (Ni), titanium (Ti), tungsten (W), or the like.

  More specifically, the internal resin 43 of the individual bump electrode 42b is formed as a protrusion along the first direction x in a region facing the individual metal layer 40c on the surface of the sealing plate 33. A plurality of the conductive films 44 of the individual bump electrodes 42b are formed along the first direction x corresponding to the piezoelectric elements 32 arranged side by side along the first direction x. That is, a plurality of individual bump electrodes 42b are formed along the first direction x. Each individual bump electrode 42 b is connected to a corresponding individual metal layer 40 c on the piezoelectric layer 38. Thereby, each individual bump electrode 42b is electrically connected to the lower electrode layer 37 via the individual metal layer 40c.

  In addition, the internal resin 43 of the common bump electrode 42 a is formed in a protruding shape along the first direction x in a region facing the second common metal layer 40 b on the surface of the sealing plate 33. As shown in FIG. 5, the internal resin 43 of the common bump electrode 42 a in this embodiment is one end of the second common metal layer 40 b (outside of the actuator unit 14) (that is, one of the upper electrode layers 39). And a position facing the piezoelectric layer 38 outside the one end of the second common metal layer 40b (that is, the element end 34a on the one side of the piezoelectric element 32). Has been. The conductive film 44 of the common bump electrode 42a is formed so as to cover the entire surface of the internal resin 43 in the second direction y. That is, the common bump electrode 42a is formed from the position overlapping the second common metal layer 40b to the position facing the piezoelectric layer 38 outside the one end of the second common metal layer 40b. In other words, a part of the common bump electrode 42a is disposed so as to be shifted outward from one end portion of the second common metal layer 40b. Note that a plurality of the conductive films 44 of the common bump electrode 42a in the present embodiment are formed along the first direction x corresponding to the piezoelectric elements 32 arranged in parallel along the first direction x. . As shown in FIG. 4, the width Hb (the dimension in the first direction x) of each common bump electrode 42a (conductive film 44) is the lower electrode layer 37 (that is, the lower electrode layer) in the region overlapping the common bump electrode 42a. It is formed wider (larger) than the width of the end portion 37). Each common bump electrode 42a is connected to the second common metal layer 40b at a plurality of locations along the first direction x on the piezoelectric layer 38. Thereby, each common bump electrode 42a is electrically connected to the upper electrode layer 39 through the second common metal layer 40b.

  The sealing plate 33 and the pressure chamber forming substrate 29 on which the vibration plate 31 and the piezoelectric element 32 are laminated are joined by an adhesive 48 with each bump electrode 42 interposed therebetween. The adhesive 48 is disposed in a strip shape along the first direction x at a position covering both sides of each bump electrode 42 and the first common metal layer 40a to which the bump electrode 42 is not connected. Specifically, as shown in FIG. 3, the adhesive 48a disposed outside the individual bump electrode 42b (on the side opposite to the common bump electrode 42a side) is applied to the individual metal layer 40c in the second direction y. It extends from above to the diaphragm 31 beyond the end of the individual metal layer 40c. The adhesive 48b disposed between the individual bump electrode 42b and the common bump electrode 42a is applied to the second common metal on the piezoelectric layer 38 between the second common metal layer 40b and the individual metal layer 40c. It is filled between the layer 40b and the individual metal layer 40c and between the individual bump electrode 42b and the common bump electrode 42a. That is, as shown in FIG. 5, the space between the common bump electrode 42a and the piezoelectric layer 38 is filled with the adhesive 48b. In other words, a part of the adhesive 48 b is provided between the portion of the common bump electrode 42 a facing the piezoelectric layer 38 and the piezoelectric layer 38.

  Further, as shown in FIG. 3, the adhesive 48c disposed on the inner side (the side opposite to the individual bump electrode 42b side) than the common bump electrode 42a is applied to the second common metal layer 40b in the second direction y. From the top, it extends beyond the end of the second common metal layer 40b to a position overlapping with one end of the partition region 35. One end of the partition region 35 is covered with the adhesive 48c. For this reason, deformation of the piezoelectric element 32 at one end of the partition region 35 is suppressed. Further, the adhesive 48d that covers the first common metal layer 40a is disposed on the diaphragm 31 from the position overlapping the other end of the partition region 35 in the second direction y beyond the first common metal layer 40a. It is extended to. The adhesive 48d covers the other end of the partition region 35 and the other end 34b of the piezoelectric element 32. For this reason, deformation of the piezoelectric element 32 at the other end of the partition region 35 is suppressed. Further, deformation of the piezoelectric element 32 at the element end 34b on the other side of the piezoelectric element 32 is suppressed.

  As the adhesive 48, a coating type and thermosetting resin is preferably used. By using a coating-type resin, the resin can easily rotate below the common bump electrode 42a, and the adhesive 48 can be easily formed at the position. In addition, a photosensitive and thermosetting resin can also be used. In the case of a resin having photosensitivity, a resin having a slight fluidity is desirable when the substrate to be the pressure chamber forming substrate 29 and the substrate to be the sealing plate 33 are bonded and the resin is fully cured. That is, it is desirable that the resin wraps around the common bump electrode 42a. If a material having photosensitivity is used as the adhesive 48, the adhesive 48 can be accurately placed at a predetermined position by exposure and development after the adhesive 48 is applied. Thereby, the protrusion of the adhesive 48 can be suppressed, and the recording head 3 can be downsized. In other words, the adhesive 48 can be prevented from interfering with other parts constituting the actuator unit 14 by protruding from the planned position, and the adhesive 48 can be brought as close as possible to the part. As a result, the actuator unit 14 can be reduced in size, and consequently the recording head 3 can be reduced in size. In addition, as such resin, resin which has an epoxy resin, an acrylic resin, a phenol resin, a polyimide resin, a silicone resin, a styrene resin etc. as a main component is desirable, for example.

  The recording head 3 formed as described above introduces ink from the ink cartridge 7 into the pressure chamber 30 via the ink introduction path, the reservoir 18, the common liquid chamber 25, and the individual communication path 26. In this state, when a signal from the drive circuit 46 is supplied to the piezoelectric element 32 via each bump electrode 42, the piezoelectric element 32 is driven and pressure fluctuation occurs in the pressure chamber 30. The recording head 3 uses this pressure fluctuation to eject ink droplets from the nozzles 22 via the nozzle communication path 27.

  Thus, in the recording head 3 according to the present embodiment, as shown in FIG. 5, a part of the common bump electrode 42a faces the piezoelectric layer 38 via the adhesive 48b. When the element 32) is deformed, the stress can be prevented from concentrating on the piezoelectric layer 38 at the end of the upper electrode layer 39. That is, the electric field generated in the piezoelectric layer 38 sandwiched between the lower electrode layer 37 and the upper electrode layer 39 is larger than the electric field generated in the piezoelectric layer 38 sandwiched between the lower electrode layer 37 and the common bump electrode 42a. Since a weak electric field is generated, it is possible to suppress the occurrence of stress accompanying rapid deformation in the piezoelectric layer 38 at the end of the upper electrode layer 39. Accordingly, a boundary (one side of the piezoelectric element 32) between a portion not sandwiched between the lower electrode layer 37 and the upper electrode layer 39 and a portion sandwiched between the lower electrode layer 37 and the upper electrode layer 39 is obtained. It is possible to suppress the occurrence of cracks or the like in the piezoelectric layer 38 at the element end 34a). As a result, the reliability of the piezoelectric element 32 is improved, and as a result, the reliability of the recording head 3 is improved.

  Further, since the adhesive 48b is provided between the piezoelectric layer 38 and the portion of the common bump electrode 42a facing the piezoelectric layer 38, the voltage applied between the common bump electrode 42a and the lower electrode layer 37. Can be divided into the adhesive 48 b and the piezoelectric layer 38. Therefore, an electric field weaker than that of the piezoelectric layer 38 sandwiched between the lower electrode layer 37 and the upper electrode layer 39 is more reliably applied to the piezoelectric layer 38 facing the common bump electrode 42a via the adhesive 48b. Can be generated. In particular, in the present embodiment, since the second common metal layer 40b is laminated on the upper electrode layer 39, the distance between the common bump electrode 42a and the piezoelectric layer 38 can be further increased. Thereby, a weak electric field can be generated by the piezoelectric layer 38 facing the common bump electrode 42a. As a result, the stress applied to the boundary between the portion of the piezoelectric layer 38 that is about to deform and the portion that is not deformed can be relaxed. In addition, a boundary between a portion not sandwiched between the lower electrode layer 37 and the upper electrode layer 39 and a portion sandwiched between the lower electrode layer 37 and the upper electrode layer 39 (on one side of the piezoelectric element 32). The deformation of the piezoelectric layer 38 at the element end 34a) can be suppressed by the adhesive 48b. By this. It is possible to further suppress the occurrence of cracks or the like in the piezoelectric layer 38 at this boundary.

  Further, since the width Hb of the common bump electrode 42a is wider than the width He of the lower electrode layer 37 in the region overlapping with the common bump electrode 42a, the common bump electrode 42a is shifted in the first direction x due to a manufacturing error or the like. However, the area of the region where the common bump electrode 42a and the lower electrode layer 37 overlap is difficult to change. Thereby, an electric field can be generated more reliably between the lower electrode layer 37 and the common bump electrode 42a. As a result, the occurrence of cracks or the like in the piezoelectric layer at the element end 34a on one side of the piezoelectric element 32 can be more reliably suppressed.

  In this embodiment, since the bump electrode 42 includes the elastic internal resin 43 and the conductive film 44 covering the surface of the internal resin 43, the pressure chamber forming substrate 29 and the sealing plate 33 are provided. When joining, it is possible to suppress the pressure applied between the pressure chamber forming substrate 29 and the sealing plate 33 in order to ensure conduction between the bump electrode 42 and each electrode layer. As a result, damage to the pressure chamber forming substrate 29 or the sealing plate 33 can be suppressed. In addition, each bump electrode 42 is electrically connected to the lower electrode layer 37 and the upper electrode layer 39 on the piezoelectric layer 38 formed in a region outside the partition region 35. The space | interval with the board 33 can be ensured more reliably. That is, since the bump electrode 42 is disposed at a position where the dimension (height) from the surface of the vibration plate 31 is relatively large (high), the interval between the piezoelectric element 32 and the sealing plate 33 can be more reliably ensured. Can do. In particular, in the present embodiment, since the bump electrode 42 is disposed on the metal layer 40, the interval between the piezoelectric element 32 and the sealing plate 33 can be more reliably ensured. Thereby, it is possible to suppress the deformation of the piezoelectric element 32 from being hindered by the sealing plate 33.

  Next, a method for manufacturing the recording head 3, particularly the actuator unit 14, will be described. The actuator unit 14 according to this embodiment includes a silicon single crystal substrate (silicon wafer) in which a plurality of regions to be the sealing plate 33 are formed, a region in which the vibration plate 31 and the piezoelectric element 32 are stacked to form the pressure chamber forming substrate 29. Is obtained by cutting into pieces in a state where a plurality of silicon single crystal substrates (silicon wafers) formed by bonding are bonded together with an adhesive 48.

  More specifically, in the silicon single crystal substrate on the sealing plate 33 side, first, the drive circuit 46 and the like are formed on the lower surface (the surface on the side facing the pressure chamber forming substrate 29) by a semiconductor process. Next, after a resin film is formed on the lower surface of the silicon single crystal substrate and the internal resin 43 is formed by a photolithography process and an etching process, the internal resin 43 is melted by heating to round its corners. Thereafter, a metal film is formed on the surface by vapor deposition or sputtering, and the conductive film 44 is formed by a photolithography process and an etching process. Thereby, a plurality of regions to be the sealing plates 33 corresponding to the individual recording heads 3 are formed on the silicon single crystal substrate.

  On the other hand, in the silicon single crystal substrate on the pressure chamber forming substrate 29 side, first, the vibration plate 31 is laminated on the upper surface (the surface on the side facing the sealing plate 33). Next, the lower electrode layer 37, the piezoelectric layer 38, the upper electrode layer 39, and the like are sequentially patterned by a semiconductor process to form the piezoelectric element 32 and the like. Thereby, a plurality of regions to be pressure chamber forming substrates 29 corresponding to the individual recording heads 3 are formed on the silicon single crystal substrate. Thereafter, an adhesive layer is formed on the surface, and an adhesive 48 is formed at a predetermined position by a photolithography process. Specifically, when a coating type resin is used as the adhesive 48, a method of coating the resin with a despacer, a method of coating a printing plate on a silicon single crystal substrate and coating a resin with a squeegee, once applied to a film, etc. The shape of the adhesive 48 is patterned at a predetermined position using various printing methods such as a method of transferring the resin to the silicon single crystal substrate. Further, when a resin having photosensitivity and thermosetting is used as the adhesive 48, an adhesive layer having elasticity by applying a liquid resin on the diaphragm 31 using a spin coater or the like and heating. Form. Then, the shape of the adhesive 48 is patterned at a predetermined position by exposure and development. As described above, when the adhesive 48 has photosensitivity, the adhesive 48 can be patterned with high accuracy by the photolithography process.

  If the adhesive 48 is formed, both silicon single crystal substrates are joined. Specifically, one of the silicon single crystal substrates is relatively moved toward the other silicon single crystal substrate, and the adhesive 48 is sandwiched between the two silicon single crystal substrates. In this state, both silicon single crystal substrates are pressed from above and below against the elastic restoring force of the bump electrode 42. Thereby, the bump electrode 42 is crushed and conduction can be ensured. Further, the adhesive 48b provided between the common bump electrode 42a and the individual bump electrode 42b goes around below the common bump electrode 42a. And it heats to the hardening temperature of the adhesive agent 48, pressurizing. As a result, in a state where the bump electrode 42 is crushed, the adhesive 48 is cured and the two silicon single crystal substrates are bonded. The adhesive 48b provided between the piezoelectric layer 38 and the common bump electrode 42a can be injected later. That is, the other adhesive is cured by the above method, and then the adhesive is injected into the gap between the common bump electrode and the individual bump electrode with a despacer or the like, so that the piezoelectric layer and the common bump electrode It may be filled between. In this case, a liquid adhesive having no photosensitivity can be used as an adhesive to be injected later.

  When both silicon single crystal substrates are bonded, the silicon single crystal substrate on the pressure chamber forming substrate 29 side is polished from the lower surface side (the side opposite to the silicon single crystal substrate side on the sealing plate 33 side), and the pressure chamber The silicon single crystal substrate on the formation substrate 29 side is thinned. Thereafter, the pressure chamber 30 is formed on the thin silicon single crystal substrate on the pressure chamber forming substrate 29 side by a photolithography process and an etching process. Finally, scribing is performed along a predetermined scribe line and cut into individual actuator units 14.

  The actuator unit 14 manufactured by the above process is positioned and fixed to the flow path unit 15 (communication substrate 24) using an adhesive or the like. The recording head 3 is manufactured by joining the head case 16 and the flow path unit 15 in a state where the actuator unit 14 is housed in the housing space 17 of the head case 16.

  By the way, in above-mentioned 1st Embodiment, although arrange | positioned so that a part of each adhesive agent 48 might overlap with the edge part of the pressure chamber 30 (partition area | region 35), it is not restricted to this. In the actuator unit 14 ′ in the second embodiment shown in FIG. 6, the adhesives 48 ′ are arranged so as to avoid the area overlapping with the pressure chamber 30. In other words, each adhesive 48 ′ is disposed at a position that does not overlap the partition region 35. Specifically, the adhesive 48a ′ disposed on the outer side of the individual bump electrode 42b (the side opposite to the common bump electrode 42a side) is similar to the adhesive 48a of the first embodiment in the second direction y. Further, it extends from above the individual metal layer 40c to the diaphragm 31 beyond the end of the individual metal layer 40c. The adhesive 48b 'disposed between the individual bump electrode 42b and the common bump electrode 42a is formed between the second common metal layer 40b and the individual metal layer 40c, like the adhesive 48b of the first embodiment. On the piezoelectric layer 38, it is filled between the second common metal layer 40b and the individual metal layer 40c and between the individual bump electrode 42b and the common bump electrode 42a. The adhesive 48 c ′ disposed inside the common bump electrode 42 a (on the side opposite to the individual bump electrode 42 b side) is formed on the second common metal layer 40 b in a region outside the partition region 35. The adhesive 48d ′ that covers a part of the first common metal layer 40a is applied to the first common metal layer from the first common metal layer 40a in the region outside the partition region 35 in the second direction y. It extends beyond the end of 40a to a region corresponding to between the piezoelectric elements 32. Since other configurations are the same as those of the first embodiment described above, description thereof is omitted.

  As described above, in the present embodiment, since the adhesive 48 ′ is formed in a region that is out of the partition region 35, the deformation of the diaphragm 31 in the partition region 35 is not easily inhibited. Thereby, the pressure fluctuation due to the driving of the piezoelectric element 32 can be efficiently transmitted to the ink in the pressure chamber 30. In addition, it is possible to suppress a decrease in bonding ability due to the vibration of the piezoelectric element 32 being transmitted to the adhesive 48 ′. As a result, the reliability of the recording head 3 can be improved. Furthermore, since the adhesive 48 ′ and the partition region 35 do not overlap, it is possible to suppress variation in the amount of deformation of the diaphragm 31 due to variations in the position of the adhesive 48 ′. Accordingly, even when an adhesive having no photosensitivity, that is, an adhesive that easily varies in the bonding position, is used as the adhesive 48 ′, it is possible to suppress variation in ink ejection characteristics.

  In each of the above-described embodiments, the piezoelectric layer 38 and the first common metal layer 40a are formed in two rows corresponding to the rows of the pressure chambers 30 formed in two rows. 38 and the first common metal layer 40a are separately formed for each row of the pressure chambers 30, but the present invention is not limited thereto. For example, in the actuator unit 14 ′ in the third embodiment shown in FIG. 7, the piezoelectric layer 38 ′ and the first common metal layer 40 a ′ that are common to the rows of the pressure chambers 30 formed in two rows, It is formed in one row.

Specifically, the piezoelectric layer 38 ′ is formed across the piezoelectric elements 32 on both sides in the second direction y. That is, the end of one side (left side in FIG. 7) in the second direction y of the piezoelectric layer 38 ′ is one (left side in FIG. 7) of individual metal layers 40c arranged in parallel in two rows. It extends to a region overlapping with 40c. The other end (right side in FIG. 7) of the piezoelectric layer 38 ′ in the second direction y is the other (right side in FIG. 6) individual metal layer of the individual metal layers 40c arranged in two rows. It extends to a region overlapping with 40c. Further, the first common metal layer 40a ′ is arranged in the second direction y with the end on one side (left side in FIG. 7) on the other side (the inner side in the actuator unit 14 ′) of the partition region 35 (pressure chamber 30). It is formed from the overlapping region to a region overlapping with the end portion on the other side (inside in the actuator unit 14 ′) of the other (right side in FIG. 7) partition region 35 (pressure chamber 30). Then, the adhesive 48d ′ covering a part of the first common metal layer 40a ′ has one end of the first common metal layer 40a ′ in a region away from the one partition region 35 in the second direction y. The first common metal layer 40 a ′ is disposed across the other end of the first common metal layer 40 a ′ in a region away from the other partition region 35. That is, the adhesive 48 d ′ in the present embodiment is formed in one row on the first common metal layer 40 a ′ in the region outside the partition region 35. Since other configurations are the same as those of the second embodiment described above, description thereof is omitted.

  Furthermore, in each of the above-described embodiments, the sealing plate 33 provided with the drive circuit 46 is illustrated as the circuit board of the present invention, but the present invention is not limited to this. For example, the driving circuit may be provided on another member (such as a driving IC) different from the sealing plate, and only the wiring for relaying a signal from the driving circuit may be formed on the sealing plate 33. That is, the circuit board in the present invention is not limited to a sealing plate provided with a drive circuit, but includes a sealing plate in which only wiring is formed.

  In the above-described embodiment, the lower electrode layer 37 and the upper electrode layer 39 and the corresponding bump electrodes 42 are connected to the metal layer 40 laminated on the piezoelectric layer 38, respectively. Not limited. On the piezoelectric layer, at least some of the plurality of bump electrodes may be electrically connected to either the lower electrode layer or the upper electrode layer. Furthermore, in the above-described embodiment, the bump electrode 42 is provided on the sealing plate 33 side, but the present invention is not limited to this. For example, the bump electrode can be provided on the pressure chamber substrate side. In the manufacturing method described above, the adhesive 48 is applied to the silicon single crystal substrate on the pressure chamber forming substrate 29 side, but the present invention is not limited to this. For example, the adhesive can be applied to the silicon single crystal substrate on the sealing plate side.

  In the embodiment described above, the ink jet recording head mounted on the ink jet printer is exemplified as the ink jet head, but the present invention can also be applied to a liquid ejecting liquid other than ink. For example, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, FED (surface emitting display), a biochip (biochemical element) The inkjet head of the present invention can also be used for a bio-organic matter ejecting head or the like used for the production of ().

  DESCRIPTION OF SYMBOLS 1 ... Printer, 3 ... Recording head, 14 ... Actuator unit, 15 ... Flow path unit, 16 ... Head case, 17 ... Storage space, 18 ... Reservoir, 21 ... Nozzle plate, 22 ... Nozzle, 24 ... Communication board | substrate, 25 ... Common liquid chamber, 26 ... Individual communication passage, 29 ... Pressure chamber forming substrate, 30 ... Pressure chamber, 31 ... Vibration plate, 32 ... Piezoelectric element, 33 ... Sealing plate, 35 ... Partition area, 37 ... Lower electrode layer, 38 ... Piezoelectric layer, 39 ... Upper electrode layer, 40 ... Metal layer, 42 ... Bump electrode, 43 ... Internal resin, 44 ... Conductive film, 46 ... Drive circuit, 48 ... Adhesive

Claims (4)

A pressure chamber forming substrate in which a plurality of pressure chambers communicating with the nozzle are formed along the first direction;
A diaphragm that divides a surface on one side of the pressure chamber, and allows deformation of the partitioned region;
In a region corresponding to the pressure chamber, a piezoelectric element in which a first electrode layer, a piezoelectric layer, and a second electrode layer are stacked in order from the surface opposite to the pressure chamber side of the diaphragm;
A circuit board that outputs a signal that drives the piezoelectric element, and is arranged with a gap to the diaphragm in a state where a plurality of bump electrodes are interposed between the diaphragm and the diaphragm,
In a second direction orthogonal to the first direction, one end of the second electrode layer is extended to the outside from one end of the partition region, and one end of the first electrode layer An end on one side and an end on one side of the piezoelectric layer are extended to the outside from an end on one side of the second electrode layer,
The bump electrode that is electrically connected to the second electrode layer extends from a position that overlaps the second electrode layer to a position that faces the piezoelectric layer outside the one end of the second electrode layer. An inkjet head characterized by being formed.   The size of the bump electrode electrically connected to the second electrode layer in the first direction is such that the first electrode layer in a region overlapping the bump electrode electrically connected to the second electrode layer. The inkjet head according to claim 1, wherein the size is larger than the dimension in the first direction.   The inkjet head according to claim 1, wherein an adhesive is provided between a portion of the bump electrode facing the piezoelectric layer and the piezoelectric layer.   An ink jet printer comprising the ink jet head according to any one of claims 1 to 3.

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