JP2017147356A - Piezoelectric device and liquid ejecting head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device and a liquid ejecting head which are improved in reliability by suppressing destruction of a piezoelectric layer.SOLUTION: The piezoelectric device includes a piezoelectric element 300 in which a first electrode 60, a piezoelectric layer 70, and a second electrode 80 are stacked. The piezoelectric layer 70 is provided with a conductive electric field alleviating portion 130 connected to one end portion 80a of the second electrode 80 and a spaced electrode 140 connected to the second electrode 80 via the electric field alleviating portion 130. The electric field alleviating portion 130 has higher electric resistance than the second electrode 80. Furthermore, an insulating portion 150 is provided between the spaced electrode 140 and a first lead electrode 91 connected to the first electrode 60.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a piezoelectric device including a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode provided on a substrate via a vibration plate, and a liquid ejecting head.

  A typical example of a liquid ejecting head that ejects droplets is an ink jet recording head that ejects ink droplets. The ink jet recording head includes, for example, a flow path forming substrate in which a pressure generation chamber communicating with a nozzle opening is formed, and a piezoelectric actuator that is a piezoelectric element provided on one surface side of the flow path forming substrate. In addition, there is known a technique in which an ink droplet is ejected from a nozzle opening by causing a pressure change in ink in a pressure generating chamber by a piezoelectric actuator.

  The piezoelectric actuator includes a first electrode, a piezoelectric layer, and a second electrode provided on the flow path forming substrate. A piezoelectric actuator is known in which a first electrode is an individual electrode for each active part and a second electrode is a common electrode common to a plurality of active parts (see Patent Documents 1 and 2, etc.).

JP 2009-172878 A JP 2009-078439 A

  When the end of the active part is defined by the end of the second electrode, the electric field concentrates on the piezoelectric layer at the end of the second electrode, and reliability such as destruction of the piezoelectric layer due to the electric field concentration decreases. There is a problem that it ends up.

  Such a problem is not limited to a liquid jet head typified by an ink jet recording head, and similarly exists in other piezoelectric devices.

  In view of such circumstances, it is an object of the present invention to provide a piezoelectric device and a liquid ejecting head that have improved reliability by suppressing destruction of a piezoelectric layer.

An aspect of the present invention that solves the above problem includes a piezoelectric element that is provided above a substrate and includes a first electrode, a piezoelectric layer, and a second electrode laminated from the substrate side. A conductive electric field relaxation part connected to one end of the second electrode, and a separation electrode connected to the second electrode through the electric field relaxation part are provided, and the electric field relaxation part is more than the second electrode. The piezoelectric device is characterized by high electrical resistance.
In this aspect, the change in electric field strength can be mitigated at the boundary between the active part and the inactive part defined by the separation electrode. Thereby, it can suppress that stress concentrates on the said boundary, can suppress destruction by stress concentration, and can improve the reliability of a piezoelectric device. Further, the electric field of the second electrode occupying the main part of the active part is not reduced only by reducing the electric field strength of the separation electrode. Thereby, the piezoelectric device can obtain a sufficient piezoelectric characteristic, that is, a displacement characteristic that causes a large displacement with a small voltage by applying a sufficient electric field to the main part of the active part.

  In addition, it is preferable that an insulating part having an insulating property connected to the separation electrode is provided, and the first electrode is connected to the insulating part. According to this, it is possible to suppress a short circuit between the first electrode and the second electrode.

  Moreover, it is preferable that the said insulation part is formed with the electroconductive material whose electrical resistance value is higher than the said separation electrode. According to this, an insulating part can be formed in the same process as an electric field relaxation part, and a manufacturing process can be simplified.

  A protective substrate bonded to the piezoelectric element side of the substrate; wherein the insulating portion is formed of an insulating resin; and the protective substrate is bonded to the insulating portion by the resin. preferable. According to this, since the insulating part can be formed when the protective substrate is bonded to the substrate, the manufacturing process can be simplified. Since the resin for bonding the protective substrate is integrated with the insulating portion, the protective substrate can be made difficult to peel off.

According to another aspect of the invention for solving the above problem, a liquid ejecting head includes the piezoelectric device described in the above aspect.
In this aspect, a liquid ejecting head in which destruction of the piezoelectric layer is suppressed and reliability is improved is provided.

1 is a schematic diagram illustrating an example of an ink jet recording apparatus. FIG. 3 is an exploded perspective view of the recording head according to the first embodiment. FIG. 3 is a plan view of the recording head according to the first embodiment. FIG. 4 is a cross-sectional view taken along line AA ′ in FIG. 3. It is sectional drawing to which the principal part of FIG. 4 was expanded. 6 is a plan view of a modification of the recording head according to Embodiment 1. FIG. It is a graph which shows the strength of an electric field. FIG. 6 is a cross-sectional view illustrating a main part of a recording head according to Embodiment 2. FIG. 6 is a cross-sectional view illustrating a main part of a recording head according to a third embodiment.

<Embodiment 1>
FIG. 1 shows a schematic configuration of an ink jet recording apparatus which is an example of a liquid ejecting apparatus according to the present embodiment.

  In the ink jet recording apparatus I, the recording head 1 is provided with a cartridge 2 constituting an ink supply means in a detachable manner, and the carriage 3 on which the recording head 1 is mounted is axially directed to a carriage shaft 5 attached to the apparatus body 4. It is provided to be movable.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head 1 is mounted is moved along the carriage shaft 5. On the other hand, the apparatus main body 4 is provided with a conveyance roller 8 as a conveyance means, and a recording sheet S which is a recording medium such as paper is conveyed by the conveyance roller 8. Note that the conveyance means for conveying the recording sheet S is not limited to the conveyance roller, and may be a belt, a drum, or the like.

  In addition, as the ink jet recording apparatus I, an example in which the recording head 1 is mounted on the carriage 3 and moves in the main scanning direction is illustrated, but the configuration is not particularly limited. The ink jet recording apparatus I may be, for example, a so-called line recording apparatus that performs printing by fixing the recording head 1 and moving a recording sheet S such as paper in the sub-scanning direction.

  Further, the ink jet recording apparatus I has a configuration in which the cartridge 2 which is a liquid storage means is mounted on the carriage 3, but is not particularly limited thereto. For example, liquid storage means such as an ink tank may be fixed to the apparatus main body 4 and the liquid storage means and the recording head 1 may be connected via a supply pipe such as a tube. Further, the liquid storage means may not be mounted on the ink jet recording apparatus I.

  An ink jet recording head (hereinafter also referred to as a recording head) will be described with reference to FIGS. FIG. 2 is an exploded perspective view of the ink jet recording head of this embodiment, and FIG. 3 is a plan view of FIG. 4 is a cross-sectional view taken along the line AA ′ of FIG.

  A pressure generating chamber 12 is formed in a flow path forming substrate 10 that is an example of a substrate, and a plurality of nozzle openings 21 that discharge ink of the same color are arranged in parallel in the pressure generating chamber 12 partitioned by a plurality of partition walls 11. Are arranged along the direction. Hereinafter, this direction is referred to as a direction in which the pressure generating chambers 12 are arranged side by side or a first direction X. A direction orthogonal to the first direction X is referred to as a second direction Y. Furthermore, a direction that intersects both the first direction X and the second direction Y is referred to as a third direction Z. The coordinate axes shown in each figure represent a first direction X, a second direction Y, and a third direction Z. The direction of the arrow is also referred to as a positive (+) direction, and the opposite direction is also referred to as a negative (-) direction. . In the present embodiment, the relationship in each direction (X, Y, Z) is orthogonal, but the arrangement relationship of each component is not necessarily limited to being orthogonal.

  An ink supply path 13 having an opening area reduced by narrowing one side of the pressure generation chamber 12 from the first direction X on one end side in the second direction Y of the pressure generation chamber 12 of the flow path forming substrate 10; A communication passage 14 having substantially the same width as the pressure generation chamber 12 in the first direction X is partitioned by a plurality of partition walls 11. On the outside of the communication path 14 (on the side opposite to the pressure generation chamber 12 in the second direction Y), a communication portion 15 that forms a part of the manifold 100 serving as a common ink chamber for each pressure generation chamber 12 is formed. ing. That is, the flow path forming substrate 10 is formed with a liquid flow path including a pressure generation chamber 12, an ink supply path 13, and a communication portion 15.

  On one side of the flow path forming substrate 10, that is, the surface where the liquid flow path such as the pressure generation chamber 12 opens, a nozzle plate 20 having a nozzle opening 21 communicating with each pressure generation chamber 12 is provided with an adhesive. Or a heat-welded film or the like. Nozzle openings 21 are arranged in the nozzle plate 20 in the first direction X.

  As a material of the nozzle plate 20, for example, a metal such as stainless steel (SUS), an organic substance such as a polyimide resin, a silicon single crystal substrate, or the like can be used. In addition, by using a silicon single crystal substrate as the nozzle plate 20, the linear expansion coefficients of the nozzle plate 20 and the flow path forming substrate 10 are made equal, and warpage due to heating or cooling, generation of cracks due to heat, peeling, etc. Can be suppressed.

  A vibration plate 50 is formed on the surface of the flow path forming substrate 10 opposite to the nozzle plate 20 (+ Z direction side). In the present embodiment, an elastic film 51 made of silicon oxide provided on the flow path forming substrate 10 side and an insulator film 52 made of zirconium oxide provided on the elastic film 51 are provided as the diaphragm 50. I made it. The liquid flow path such as the pressure generation chamber 12 is formed by anisotropically etching the flow path forming substrate 10 from one side, and the other side of the liquid flow path such as the pressure generation chamber 12 is elastic. It is defined by the film 51. Of course, the diaphragm 50 is not particularly limited to this, and either the elastic film 51 or the insulator film 52 may be provided, or another film may be provided.

  On the vibration plate 50, a piezoelectric element 300 that causes a pressure change in the ink in the pressure generation chamber 12 is provided. The piezoelectric element 300 includes a first electrode 60 that is a conductive electrode, a piezoelectric layer 70, and a second electrode 80 that is a conductive electrode, which are sequentially stacked from the flow path forming substrate 10 side. Such a piezoelectric element 300 is displaced by applying a voltage between the first electrode 60 and the second electrode 80. That is, by applying a voltage between both electrodes, a piezoelectric strain is generated in the piezoelectric layer 70 sandwiched between the first electrode 60 and the second electrode 80. A portion where piezoelectric distortion occurs in the piezoelectric layer 70 when a voltage is applied to both electrodes is referred to as an active portion 310.

  The first electrode 60 is separated for each pressure generation chamber 12 and constitutes an individual electrode independent for each active part 310 that is a substantial drive part of the piezoelectric element 300. The first electrode 60 is formed with a width narrower than the width of the pressure generation chamber 12 in the first direction X. Further, both ends of the first electrode 60 are formed to the outside of the pressure generating chamber 12 in the second direction Y, respectively, and one end thereof (on the side opposite to the communication path 14 in the second direction Y ( The lead electrode 90 made of gold (Au) or the like is connected to the −Y direction side) The material of the first electrode 60 is not particularly limited as long as it is a metal material, and for example, platinum (Pt), iridium (Ir) or the like is preferably used.

  The piezoelectric layer 70 is continuously provided in the first direction X. Further, the width of the piezoelectric layer 70 in the second direction Y is wider than the length of the pressure generation chamber 12 in the second direction Y and is provided to the outside of the pressure generation chamber 12. In the second direction Y, the end of the piezoelectric layer 70 on the ink supply path 13 side (+ Y direction side) is located outside the end of the first electrode 60, and the end of the first electrode 60 is Covered by the piezoelectric layer 70. On the other hand, the nozzle opening 21 side (−Y direction side) of the piezoelectric layer 70 is located inside the end portion of the first electrode 60, and the end portion of the first electrode 60 is covered with the piezoelectric layer 70. Not.

The piezoelectric layer 70 is made of a piezoelectric material of the oxide having a polarization structure formed on the first electrode 60, for example, it may consist of a perovskite-type oxide represented by the general formula ABO _3. As the perovskite oxide used for the piezoelectric layer 70, for example, a lead-based piezoelectric material containing lead or a lead-free piezoelectric material containing no lead can be used.

  In the piezoelectric layer 70, recesses 71 are formed at positions corresponding to the partition walls between the pressure generation chambers 12. Thus, by providing the recess 71 in the piezoelectric layer 70, the piezoelectric element 300 can be favorably displaced.

  The second electrode 80 is provided on the opposite surface side (+ Z direction side) of the piezoelectric layer 70 from the first electrode 60 and constitutes a common electrode common to the plurality of active portions 310. The second electrode 80 is also provided in the recess 71 of the piezoelectric layer 70, but is not particularly limited thereto, and the second electrode 80 may not be provided in the recess 71.

  The material of the second electrode 80 is not particularly limited as long as it is a conductive material. For example, metal materials such as iridium (Ir), platinum (Pt), palladium (Pd), gold (Au), tungsten (W), titanium (Ti), and conductivity represented by lanthanum nickel oxide (LNO) An oxide can be used. Further, the second electrode 80 may be formed of a plurality of layers instead of a single layer.

  As described above, in the piezoelectric element 300, the first electrode 60 is provided separately for each of the plurality of active portions 310 to form individual electrodes, and the second electrode 80 is provided continuously over the plurality of active portions 310. The common electrode. Of course, the present invention is not limited to such a mode, and the first electrode 60 is provided continuously over the plurality of active portions 310 to be a common electrode, and the second electrode is provided independently for each active portion 310 to be individually provided. It may be an electrode. Further, as the diaphragm 50, the elastic film 51 and the insulator film 52 may not be provided, and only the first electrode 60 may function as the diaphragm. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm.

  The flow path forming substrate 10 includes a first lead electrode 91 and a second lead electrode 92. These are also collectively referred to as lead electrodes 90.

  The first lead electrode 91 is a lead electrode connected to each of the first electrodes 60 of each piezoelectric element 300. The second lead electrode 92 is a lead electrode connected to the second electrode 80 common to each piezoelectric element 300. In this embodiment, the 1st lead electrode 91 and the 2nd lead electrode 92 are wired so that it may be exposed to the through-hole 33 of the protective substrate 30 mentioned later. The first lead electrode 91 is connected to the first electrode 60 via a conductive layer 82 made of the same material as the second electrode 80. Of course, the first lead electrode 91 may be directly connected to the first electrode 60.

  A protective substrate 30 is bonded to the flow path forming substrate 10 via an adhesive 35. The protective substrate 30 has a manifold portion 32. The manifold part 32 penetrates the protective substrate 30 in the thickness direction and is formed across the width direction of the pressure generating chamber 12, and communicates with the communication path 14 of the flow path forming substrate 10 as described above. A manifold 100 serving as an ink chamber common to the pressure generation chamber 12 is configured.

  A piezoelectric element holding portion 31 having a space that does not hinder the movement of the piezoelectric element 300 is provided in a region facing the piezoelectric element 300 of the protective substrate 30. The piezoelectric element holding part 31 should just have the space of the grade which does not inhibit the motion of the piezoelectric element 300, and the said space may be sealed or not sealed. The protective substrate 30 can be made of substantially the same material as the thermal expansion coefficient of the flow path forming substrate 10, for example, glass or ceramic material. In this embodiment, a silicon single crystal made of the same material as the flow path forming substrate 10 is used. It formed using the board | substrate.

  The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end portion of the lead electrode 90 drawn from each piezoelectric element 300 is provided so as to be exposed in the through hole 33. A drive circuit 120 for driving the piezoelectric elements 300 arranged side by side is fixed on the protective substrate 30. As the drive circuit 120, for example, a circuit board, a semiconductor integrated circuit (IC), or the like can be used. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 121 made of a conductive wire such as a bonding wire.

  On the protective substrate 30, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded. The sealing film 41 can be made of a material having low rigidity and flexibility, and one surface of the manifold portion 32 is sealed by the sealing film 41. The fixed plate 42 is made of a relatively hard material. Since the region of the fixing plate 42 facing the manifold 100 is an opening 43 that is completely removed in the thickness direction, one surface of the manifold 100 is sealed only with a flexible sealing film 41. ing.

  In the recording head 1 having such a configuration, when ink is ejected, the ink is taken in from the liquid storage means in which the ink is stored, and the inside of the flow path is filled with the ink from the manifold 100 to the nozzle opening 21. Thereafter, in accordance with a signal from the drive circuit 120, a voltage is applied to each piezoelectric element 300 corresponding to the pressure generating chamber 12, so that the diaphragm 50 is bent together with the piezoelectric element 300. As a result, the pressure in the pressure generating chamber 12 is increased and ink droplets are ejected from the predetermined nozzle openings 21.

  The piezoelectric element 300 will be described in detail with reference to FIG. FIG. 5 is an enlarged cross-sectional view of the main part of FIG.

  In the second direction Y, the piezoelectric layer 70 of the piezoelectric element 300 according to the present embodiment extends beyond the second electrode 80 to the outside in the second direction Y. That is, there is a region where the second electrode 80 is not provided above the piezoelectric layer 70. In the region, an electric field relaxation portion 130, a separation electrode 140, and an insulating portion 150 are provided.

  The electric field relaxation part 130 is formed on the piezoelectric layer 70 with a conductive material, and is connected to one end part 80 a of the second electrode 80 in the second direction Y. Further, the electric resistance of the electric field relaxation unit 130 is higher than the electric resistance of the second electrode 80.

  In the present embodiment, the electric field relaxation unit 130 includes a first electric field relaxation unit 83 and a second electric field relaxation unit 93. The first electric field relaxation part 83 is formed to have substantially the same thickness as the second electrode 80, and the second electric field relaxation part 93 has substantially the same thickness as the second lead electrode 92, and is more than the first electric field relaxation part 83. The width in the second direction Y is narrow. The first electric field relaxation portion 83 and the second electric field relaxation portion 93 are both formed of the same material, but may be formed of different materials.

  The material of the electric field relaxation part 130 is not particularly limited as long as it has an electric resistance value higher than that of the second electrode 80 and has conductivity. For example, resin, silver, copper, and carbon paste can be mentioned. The electric field relaxation unit 130 may be formed by implanting ions of a substance (impurity) different from the electrode layer formed of the same material as the second electrode 80 and the material. That is, the electric field relaxation unit 130 is an impurity that is a substance different from the substance that constitutes the second electrode 80 and can have an electric resistance higher than that of the second electrode 80, for example, oxygen (O), nitrogen ( N), boron (B), carbon (C), fluorine (F), phosphorus (P), and at least one ion selected from the group consisting of sulfur (S) is formed of the same material as the second electrode 80 Can be formed.

  The separation electrode 140 is connected to the second electrode 80 via the electric field relaxation unit 130. As described above, since the electric field relaxation part 130 has conductivity, the separation electrode 140 is electrically connected to the second electrode 80 through the electric field relaxation part 130. Such a separation electrode 140 defines the end of the active part 310. That is, in the piezoelectric layer 70, a region sandwiched between the separation electrode 140 and the first electrode 60 is a part of the active portion 310 that is deformed and deformed by a voltage applied between the separation electrode 140 and the first electrode 60. .

  In the present embodiment, the separation electrode 140 includes a first separation electrode 84 and a second separation electrode 94. The first separation electrode 84 is formed to have substantially the same thickness as the second electrode 80. The second separation electrode 94 has substantially the same thickness as the second lead electrode 92, and is formed wider in the second direction Y than the first separation electrode 84.

  The material of the separation electrode 140 is not particularly limited as long as it is a conductive material. The separation electrode 140 is preferably formed of the same material as the second electrode 80, but may be formed of a different material.

  The insulating part 150 is formed on the piezoelectric layer 70 with an insulating material connected to the separation electrode 140. Accordingly, a part of the piezoelectric layer 70 sandwiched between the insulating part 150 and the first electrode 60 becomes an inactive part 320 that does not undergo deformation.

  In the present embodiment, the insulating unit 150 includes a first insulating unit 85 and a second insulating unit 95. The first insulating portion 85 is formed with substantially the same thickness as the second electrode 80. The second insulating portion 95 has substantially the same thickness as the second lead electrode 92 and is formed to have a width in the second direction Y narrower than that of the first insulating portion 85. The first insulating portion 85 and the second insulating portion 95 are both formed of the same material, but may be formed of different materials. The material of the insulating part 150 is not particularly limited as long as it is an insulating material, but here the insulating part 150 is formed of a metal oxide film such as silicon dioxide.

  The first electrode 60 is connected to the insulating portion 150 (second insulating portion 95) via the first lead electrode 91. As described above, since the insulating part 150 has an insulating property, the first lead electrode 91, that is, the first electrode 60 is connected to the second lead electrode 92 via the electric field relaxation part 130, the separation electrode 140, and the second lead electrode 92. The electrode 80 is not short-circuited. Since the conductive layer 82 is also connected to the insulating portion 150 (first insulating portion 85), the first electrode 60 (first lead electrode 91) is connected to the second electrode 80 (second lead) via the conductive layer 82. There is no short circuit to the electrode 92). Although the first electrode 60 is connected to the insulating unit 150 via the first lead electrode 91, the first electrode 60 may be connected to the insulating unit 150 not via the first lead electrode 91.

  The electric field relaxation unit 130, the separation electrode 140, and the insulating unit 150 that are continuous from the one end portion 80 a of the second electrode 80 described above correspond to each first electrode 60, and a plurality of the electric field relaxation units 130, 140 (See FIGS. 2 and 3).

  Note that the electric field relaxation unit 130, the separation electrode 140, and the insulating unit 150 may not be provided in a plurality corresponding to the first electrode 60. For example, as shown in FIG. 6, the electric field relaxation unit 130, the separation electrode 140, and the insulating unit 150 may be common to the plurality of first electrodes 60. In such a configuration, at least each of the first electrodes 60 and the first lead electrode 91 connected thereto are not short-circuited to the second electrode 80 and the second lead electrode 92 connected thereto. What is necessary is just to be insulated by 150. The first lead electrodes 91 connected to the first electrodes 60 may be separated so as not to be short-circuited.

  As described above, the separation electrode 140 is provided on the one end portion 80a of the second electrode 80 via the electric field relaxation portion 130 having conductivity. That is, the second electrode 80 to the electric field relaxation unit 130 and the separation electrode 140 act as an integrated electrode that applies an electric field to the piezoelectric layer 70. Therefore, the active portion 310 of the piezoelectric layer 70 is a portion sandwiched between the second electrode 80, the electric field relaxation portion 130, the separation electrode 140, and the first electrode 60.

  The electric field relaxation unit 130 has a higher electrical resistance than the second electrode 80. Thereby, the strength of the electric field applied between the separation electrode 140 and the first electrode 60 becomes weaker than the strength of the electric field applied between the second electrode 80 and the first electrode 60.

FIG. 7 is a graph showing the electric field strength. The horizontal axis indicates the position in the second direction Y, and the vertical axis indicates the strength of the electric field. The intensity of the electric field in the second electrode 80 and the electric field intensity E _0. In the electric field relaxation unit 130 connected to the second electrode 80, the electric field gradually weakens as the distance from the second electrode 80 in the second direction Y increases. The electric field strength E ₁ of the separation electrode 140 is relaxed by the electric field relaxation unit 130 and is weaker than the electric field strength E ₀ of the second electrode 80.

By providing the electric field relaxation part 130, the electric field is reduced in the separation electrode 140 that is an end part of the active part 310. As a result, the change in electric field strength is mitigated at the boundary between the active part 310 and the inactive part 320. In the example shown in the figure, the electric field strength changes from E ₁ to 0 at the boundary.

If the electric field relaxation unit 130 and the separation electrode 140 are not provided, the second electrode 80 defines the end of the active unit 310. In this case, the electric field strength changes more rapidly at the boundary between the active part 310 and the inactive part 320 than when the electric field relaxation part 130 and the separation electrode 140 are provided. In the example shown in the figure, the electric field strength changes from E ₀ to 0 at the boundary.

  In the recording head 1 of the present embodiment, the change in electric field strength is mitigated at the boundary between the active part 310 and the inactive part 320. Thereby, it is possible to suppress the concentration of stress on the boundary, to suppress the breakage due to the stress concentration, and to improve the reliability of the recording head 1. Moreover, the electric field of the second electrode 80 occupying the main part of the active part 310 is not reduced only by reducing the electric field strength of the separation electrode 140. Thereby, the recording head 1 can obtain a sufficient piezoelectric characteristic, that is, a displacement characteristic that causes a large displacement with a small voltage by applying a sufficient electric field to the main part of the active part 310.

  In the recording head 1 of this embodiment, the insulating part 150 is connected to the separation electrode 140, and the first electrode 60 is connected to the insulating part 150 via the first lead electrode 91. Thereby, a short circuit between the second electrode 80 (and the separation electrode 140 connected thereto) and the first electrode 60 (and the first lead electrode 91 connected thereto) can be suppressed.

  Such a piezoelectric element 300 is not limited to a manufacturing method, but can be formed as follows, for example. Although not particularly illustrated, first, the plurality of first electrodes 60 are formed to face the pressure generation chamber 12, and the piezoelectric layer 70 is formed. A second electrode layer made of a material for forming the second electrode 80 is formed so as to cover the first electrode 60 and the piezoelectric layer 70.

  Next, the second electrode layer is patterned to form the first removal portion 86 and the second removal portion 87. Each of the first removal portion 86 and the second removal portion 87 is a portion where a part of the second electrode layer is removed and the piezoelectric layer 70 is exposed. The second electrode layer is cut by the first removal portion 86 and the second removal portion 87, and the second electrode 80, the first separation electrode 84, and the conductive layer 82 are formed. Thus, since the second electrode 80, the first separation electrode 84, and the conductive layer 82 are formed from the second electrode layer made of the same material, man-hours can be reduced as compared with the case where they are formed of different different materials. Cost can be reduced.

  Next, the first electric field relaxation unit 83 is formed in the first removal unit 86. Specifically, the first electric field relaxation portion 83 is formed in the first removal portion 86 by depositing and patterning a material for forming the first electric field relaxation portion 83. Next, the first insulating portion 85 is formed in the second removal portion 87. Specifically, the first insulating portion 85 is formed in the second removal portion 87 by depositing and patterning a material for forming the first insulating portion 85.

  Next, the first lead electrode 91 and the second lead electrode so as to cover the piezoelectric layer 70, the second electrode 80, the first electric field relaxation portion 83, the first separation electrode 84, the first insulating portion 85, and the conductive layer 82. A lead electrode layer made of a material for forming 92 is formed.

  Next, the lead electrode layer is patterned to form the third removal portion 96 and the fourth removal portion 97. The third removal portion 96 is a through-hole from which a part of the lead electrode layer has been removed, and is a portion that communicates with the first removal portion 86. The fourth removal portion 97 is a through-hole from which a part of the lead electrode layer has been removed, and is a portion that communicates with the second removal portion 87. The lead electrode layer is separated by the third removal portion 96 and the fourth removal portion 97, and the second lead electrode 92, the second separation electrode 94, and the first lead electrode 91 are formed. In this way, since the first lead electrode 91, the second separation electrode 94, and the second lead electrode 92 are formed from the lead electrode layer made of the same material, man-hours can be reduced as compared with the case where they are formed from different materials. And cost can be reduced.

  Next, the second electric field relaxation unit 93 is formed in the third removal unit 96. Specifically, the second electric field relaxation unit 93 is formed in the third removal unit 96 by depositing and patterning a material for forming the second electric field relaxation unit 93. In the present embodiment, the first electric field relaxation portion 83 and the second electric field relaxation portion 93 are made of the same material. Next, the second insulating portion 95 is formed in the fourth removal portion 97. Specifically, the second insulating portion 95 is formed in the fourth removal portion 97 by forming and patterning a material for forming the second insulating portion 95.

  Thereafter, the recording head 1 according to this embodiment can be manufactured by forming a liquid flow path such as the pressure generating chamber 12 on the flow path forming substrate 10 and bonding the protective substrate 30 and the nozzle plate 20 together.

<Embodiment 2>
In the recording head 1 according to the first embodiment, the insulating unit 150 uses an insulating metal oxide film, but is not limited to such a mode. The insulating portion may have conductivity or may be formed of a conductive material having a higher electric resistance value than that of the separation electrode 140.

  FIG. 8 is a cross-sectional view illustrating a main part of the recording head 1 according to the second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the recording head 1 of the present embodiment, a conductive material is used as the material of the insulating part 150A, and the electric resistance of the insulating part 150A is higher than that of the separation electrode 140.

  As a material of such an insulating part 150A, a material applicable to the electric field relaxation part 130 can be used. Then, the electric resistance of the insulating part 150A is made higher than that of the electric field relaxation part 130. The insulating portion 150A is formed so that the first electrode 60 (first lead electrode 91) and the second electrode 80 (second lead electrode 92) have at least an electrical resistance through the insulating portion 150A.

  For example, like the electric field relaxation unit 130 of the first embodiment, the insulating unit 150A may be formed by implanting ions of another substance (impurity) into a conductive material. Alternatively, the insulating portion 150A may be formed by reducing the cross-sectional area of the insulating portion 150A and increasing the electrical resistance by increasing the length in the XY plane.

  In the recording head 1 according to the present embodiment, the electric field relaxation part 130 and the insulating part 150A can be formed of the same material, and the manufacturing process can be simplified.

<Embodiment 3>
FIG. 9 is a cross-sectional view illustrating a main part of the recording head 1 according to the third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the recording head 1 of the present embodiment, the insulating portion 150B is formed of an insulating resin. The resin is the same as the adhesive 35 for bonding the protective substrate 30 to the insulating portion 150B. As such a resin, for example, an epoxy resin can be used.

  As described above, the recording head 1 of the present embodiment includes the insulating portion 150B for insulating the first electrode 60 and the second electrode 80, and the adhesive 35 for bonding the protective substrate 30 to the insulating portion 150B. It is made of the same material.

  For example, when the protective substrate 30 is bonded to the flow path forming substrate 10, the insulating portion 150 </ b> B can be formed by filling the second removing portion 87 and the fourth removing portion 97 with the adhesive 35.

  In the recording head 1 according to the present embodiment, when the protective substrate 30 is bonded to the flow path forming substrate 10, the insulating portion 150B can be formed, so that the manufacturing process can be simplified. Further, since the adhesive 35 is integral with the insulating portion 150B, the adhesive strength of the adhesive 35 is improved, and the protective substrate 30 can be made difficult to peel off.

<Other embodiments>
As mentioned above, although each embodiment of this invention was described, the structure of this invention is not limited to what was mentioned above.

  In the recording head 1 according to the first to third embodiments, the first electrode 60 is an individual electrode for each piezoelectric element 300, and the second electrode 80 is a common electrode common to the piezoelectric element 300. However, the present invention is not limited to this. Not.

  The first electrode 60 may be a common electrode common to the piezoelectric elements 300, and the second electrode 80 may be an individual electrode for each piezoelectric element. In such a case, an electric field relaxation part may be connected to one end of each second electrode, and a separate electrode may be connected to each electric field relaxation part. Even in such an aspect, the same operational effects as the recording head 1 of the first embodiment can be obtained.

  The recording head 1 according to the first to third embodiments includes the insulating unit 150, but the insulating unit 150 may not be provided. For example, the insulating part 150 may not be provided between the separation electrode 140, the first lead electrode 91, and the conductive layer 82, and they may be insulated by being separated by the second removing part 87 and the fourth removing part 97. .

  In the recording head 1 according to the first to third embodiments, a part of the first lead electrode 91 is provided on the piezoelectric layer 70, but the present invention is not limited to such a mode. The first lead electrode 91 may be provided on the conductive layer 82 or the first electrode 60 instead of on the piezoelectric layer 70.

  In the recording head 1 according to the first to third embodiments, the electric field relaxation unit 130 includes a plurality of layers of the first electric field relaxation unit 83 and the second electric field relaxation unit 93. Similarly, the separation electrode 140 is composed of a plurality of layers of the first separation electrode 84 and the second separation electrode 94, and the insulating portion 150 is composed of a plurality of layers of the first insulation portion 85 and the second insulation portion 95. However, the electric field relaxation unit 130, the separation electrode 140, and the insulating unit 150 are not limited to such a configuration including a plurality of layers.

  For example, the second electric field relaxation portion 93, the second separation electrode 94, and the second insulating portion 95 that are the same layer as the first lead electrode 91 and the second lead electrode 92 may not be provided. That is, the first electric field relaxation part 83, the first separation electrode 84, and the first insulation part 85 may be an electric field relaxation part, a separation electrode, and an insulation part, respectively.

  In the above embodiment, an ink jet recording head has been described as an example of a liquid ejecting head, and an ink jet recording apparatus has been described as an example of a liquid ejecting apparatus. Of course, the present invention is intended for the whole, and can be applied to a liquid ejecting head or a liquid ejecting apparatus that ejects liquid other than ink. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bio-organic matter ejection head used for biochip production, and the like, and can also be applied to a liquid ejection apparatus including such a liquid ejection head.

  The present invention is applicable not only to a liquid jet head typified by an ink jet recording head but also to other piezoelectric devices such as an ultrasonic device such as an ultrasonic transmitter, an ultrasonic motor, a pressure sensor, and a pyroelectric sensor. be able to. Even in such a piezoelectric element device, the reliability can be improved.

DESCRIPTION OF SYMBOLS I ... Inkjet recording apparatus (liquid ejecting apparatus), 1 ... Recording head (liquid ejecting head), 10 ... Flow path forming substrate (substrate), 50 ... Vibrating plate, 60 ... First electrode, 70 ... Piezoelectric layer, 80 ... second electrode, 80a ... one end, 90 ... lead electrode, 91 ... first lead electrode, 92 ... second lead electrode, 130 ... electric field relaxation part, 140 ... remote electrode, 150, 150A, 150B ... insulating part, 300 ... Piezoelectric element, 310 ... Active part, 320 ... Inactive part

Claims (5)

A piezoelectric element provided above the substrate and laminated with a first electrode, a piezoelectric layer and a second electrode from the substrate side;
The piezoelectric layer is provided with a conductive electric field relaxation part connected to one end of the second electrode, and a separation electrode connected to the second electrode through the electric field relaxation part,
The electric field relaxation portion has an electric resistance higher than that of the second electrode. The piezoelectric device according to claim 1,
An insulating portion having an insulating property connected to the separation electrode;
The piezoelectric device, wherein the first electrode is connected to the insulating portion. The piezoelectric device according to claim 2, wherein
The said insulating part is formed with the electroconductive material whose electrical resistance value is higher than the said separation electrode. The piezoelectric device characterized by the above-mentioned. The piezoelectric device according to claim 2, wherein
A protective substrate bonded to the piezoelectric element side of the substrate;
The insulating part is formed of an insulating resin,
The piezoelectric device, wherein the protective substrate is bonded to the insulating portion with the resin. A liquid ejecting head comprising the piezoelectric device according to claim 1.

Images