Actuator, element substrate and liquid discharge head

Abstract

To provide an actuator configured so that a piezoelectric element can be suppressed from being broken.SOLUTION: An actuator 121 comprises: a vibration plate 109 vibratably provided; a first electrode layer 202 contacting a first surface 109a of the vibration plate 109; a piezoelectric element 108 having a second electrode layer 111 and a piezoelectric layer 110 having a first end 110a disposed in a first direction parallel to the first surface 109a and a second end 110b at an opposite side of the first end 110a, which is installed on the first surface 109a to pile up on the first surface 109a in a second direction perpendicular to the first surface; an electrode member 114 connected to an end part at the first end 110a side of the second electrode layer 111; and a sealing film 211 covering at least a portion of the piezoelectric element 108, in which a recessed part 211a recessed to the second direction is formed between the first end 110a and the second end 110b. A distance d2 from the second end 110b of the piezoelectric layer 108 in the first direction to the second end 110b of the recessed part 211a is longer than a distance d1 from the first end of the piezoelectric layer to the first end 110a of the recessed part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an actuator, an element substrate having the actuator, and a liquid ejection head having the element substrate. [Background technology]

[0002] Actuators that use piezoelectric bodies, whose shape changes when an electric field is applied, are used as a means for minutely and accurately moving or vibrating objects in small speakers, hard disk drives, printers (liquid ejection devices), etc. For example, a liquid ejection device having a configuration in which a liquid ejection head that ejects liquid by an actuator having a piezoelectric film is provided is known.

[0003] Patent Document 1 discloses the configuration of a liquid ejection head equipped with an actuator that is made up of a piezoelectric element that is made up of a piezoelectric film and an electrode, and a sealing film that protects the piezoelectric element. In order to ensure a sufficient amount of displacement of the piezoelectric element, a recess is formed in the sealing film of the actuator along the longitudinal direction of the piezoelectric element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-281033 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned configuration, an electrode pad (lead electrode) is formed above the piezoelectric film at one end in the longitudinal direction of the piezoelectric film, and the electrode pad is not formed overlapping the piezoelectric film at the other end opposite to the one end. An electrode member such as an electrode pad can suppress the displacement of the piezoelectric element in the same way as a sealing film. Therefore, when the distance from one end of the piezoelectric film to one end of the recess and the distance from the other end of the piezoelectric film to the other end of the recess are set to be approximately equal in the longitudinal direction of the piezoelectric film, a difference occurs in the amount of displacement at both ends in the longitudinal direction of the piezoelectric element. Then, at the end on the side where the amount of displacement is large, i.e., the end on the side where the electrode pad is not formed overlapping the piezoelectric film, the electrode may peel off from the piezoelectric film or the piezoelectric film may be destroyed, which may damage the actuator.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide an actuator that suppresses damage to a piezoelectric element. [Means for solving the problem]

[0007] In order to achieve the above object, the actuator of the present invention comprises: A vibrating plate provided so as to be vibrated; a piezoelectric element including a first electrode layer in contact with a first surface of the vibration plate, a second electrode layer, and a piezoelectric layer having a first end in a first direction parallel to the first surface and a second end opposite to the first end, the piezoelectric element being placed on the first surface with the first electrode layer, the piezoelectric layer, and the second electrode layer stacked in this order in a second direction perpendicular to the first surface; an electrode member connected to the second electrode layer at a position overlapping an end portion of the piezoelectric layer on the first end side when viewed in the second direction; a sealing film covering at least a portion of the piezoelectric element, the sealing film having a recess formed between the first end and the second end and recessed in the second direction; Equipped with In the first direction, from the second end of the piezoelectric layer to an end of the recess on the second end side. The distance is longer than the distance from the first end of the piezoelectric layer to the end of the recess on the first end side. Effect of the Invention

[0008] According to the present invention, it is possible to provide an actuator that suppresses damage to a piezoelectric element. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic diagram illustrating a configuration of an element substrate according to the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing a configuration of an actuator according to the first embodiment. [Diagram 3] FIG. 13 is a schematic diagram showing a configuration of an actuator of a comparative example. [Figure 4] 11A and 11B are diagrams illustrating the operation of an actuator of a comparative example. [Diagram 5] 5A to 5C are explanatory diagrams of the operation of the actuator of the first embodiment. [Figure 6] 5A to 5C are schematic diagrams illustrating a method for manufacturing the second flow path substrate of the first embodiment. [Figure 7] 3A to 3C are schematic diagrams illustrating a method for manufacturing the element substrate according to the first embodiment. [Figure 8] FIG. 11 is a schematic diagram showing a configuration of an actuator according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Note that the dimensions, materials, shapes, and relative positions of the components described in the embodiment may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiment.

[0011] The present invention is particularly suitable for a liquid ejection head provided in a liquid ejection device that ejects liquid onto a medium such as paper. Below, an embodiment will be described in which the present invention is applied to a liquid ejection head that is an inkjet head that ejects ink onto a recording medium by driving an actuator provided on an element substrate, thereby recording an image on the recording medium. However, the present invention can also be applied to inkjet heads that eject liquids other than ink, and to other devices.

[0012] In the following description, the piezoelectric element refers to a portion including the piezoelectric film and the lower and upper electrodes formed in the direction perpendicular to the film surface. In addition, for simplicity, a piezoelectric element may also be referred to as a piezoelectric element having an insulating film, an upper electrode pad, and a sealing film with a recess formed therein.

[0013] First Embodiment (element substrate) First, the configuration of the element substrate 10 according to the first embodiment of the present invention will be described. The element substrate 10 is an element substrate in which a plurality of ejection ports 101 for ejecting ink and flow paths communicating with the ejection ports 101 are formed, and is provided in an inkjet head. The plurality of ejection ports 101 are arranged in an arrangement direction, and each ejection port 101 is formed on the same plane. In the following description, the arrangement direction of the ejection ports 101 is referred to as the Y direction, the ejection direction of ink from the ejection ports 101 is referred to as the Z direction, and the in-plane direction of the ejection port surface in which the ejection ports 101 are formed and intersects with the Y direction is referred to as the X direction. In the first embodiment, the X direction, the Y direction, and the Z direction are mutually orthogonal.

[0014] 1(a) and (b) are schematic diagrams showing the configuration of an element substrate 10 according to a first embodiment. The element substrate 10 is an element substrate configured by combining three types of substrates (a first flow path substrate 105, a second flow path substrate 106, and a third flow path substrate 107). The element substrate 10 is provided in a liquid ejection head provided in a liquid ejection device such as a printer, and ejects liquid (droplets) from ejection ports 101 by driving an actuator 121 provided inside.

[0015] A plurality of flow path blocks 100 each including an ejection port 101 are formed on one element substrate 10. Fig. 1(a) is a perspective view of a plurality of flow path blocks 100, as viewed from the side opposite to an ejection port surface including ejection ports 101. Fig. 1(b) is a cross-sectional view taken along line AA in Fig. 1(a).

[0016] The flow path block 100 includes ejection ports 101, pressure chambers 102 communicating with the ejection ports 101, and supply flow paths 103 connected to the pressure chambers 102. A common liquid chamber 104 is connected to the supply flow paths 103 of the element substrate 10, and ink is supplied from the common liquid chamber 104 to each pressure chamber 102 through each supply flow path 103. In Figures 1(a) and (b), the flow direction of the ink is indicated by an arrow.

[0017] As shown in FIG. 1(b), the element substrate 10 of the first embodiment is configured by stacking a first flow path substrate 105, a second flow path substrate 106, and a third flow path substrate 107 in the Z direction. The first flow path substrate 105 is a substrate on which a flow path for supplying ink from a common liquid chamber 104 to a pressure chamber 102 is formed. The second flow path substrate 106 is a substrate having an actuator 121 including a piezoelectric element 108 and a pressure chamber 102. The third flow path substrate 107 is a substrate including an ejection port surface on which an ejection port 101 is formed. In the case where the element substrate 10 is mounted on a liquid ejection head and ink is ejected vertically downward, the element substrate 10 is configured by arranging the first flow path substrate 105, the second flow path substrate 106, and the third flow path substrate 107 in this order from the top.

[0018] The element substrate 10 is provided with piezoelectric elements 108 corresponding to each ejection port 101. In other words, a supply flow path 103, a pressure chamber 102, and an ejection port 101 are formed corresponding to each piezoelectric element 108. The pressure chamber 102 is separated from the adjacent pressure chamber 102 in the Y direction by a partition wall, and the corresponding piezoelectric element 108 is not directly affected by the adjacent piezoelectric element 108. The piezoelectric element 108 is disposed on a mounting surface 109a of a vibration plate 109 provided in the element substrate 10. The piezoelectric element 108 and the vibration plate 109 constitute an actuator 121 that generates energy to eject liquid such as ink from the ejection port 101.

[0019] The diaphragm 109 is configured to be vibrable, and its periphery is fixed (constrained). For example, a first constraint region 118 which is one end of the diaphragm 109 in the X direction, and a second constraint region 119 which is the other end in the X direction are fixed so as not to vibrate. A part of the unconstrained region of the diaphragm 109 functions as a mounting surface (first surface) 109a on which the piezoelectric element 108 is mounted. In the first embodiment, the mounting surface 109a is approximately parallel to the X direction and the Y direction.

[0020] The first constraining region 118 is a region where the mounting surface 109a of the diaphragm 109 is joined to the third flow path substrate 107, and the diaphragm 109 is constrained such that vibration is suppressed by the third flow path substrate 107. The second constraining region 119 is a region where the back surface 109b (second surface) of the mounting surface 109a of the diaphragm 109 is joined to the base layer 122 of the second flow path substrate 106, and the diaphragm 109 is constrained such that vibration is suppressed by the base layer 122. The diaphragm 109 is constrained in the first constraining region 118 and the second constraining region 119 as described above, and therefore vibration of the diaphragm 109 is suppressed in each region.

[0021] Ink contained in the pressure chamber 102 forms a meniscus at the ejection port 101 in a stable state. When a voltage waveform is applied to the piezoelectric element 108 in accordance with an ejection signal, the piezoelectric element 108 deforms, causing the pressure chamber 102 to expand or contract. By combining the expansion and contraction actions, a droplet 113 is generated from the meniscus, and the ink droplet is ejected toward the outside air (downward in FIG. 1(b)).

[0022] In the first embodiment, the actuator 121 composed of the piezoelectric element 108 and the vibration plate 109 is regarded as a part of the second flow path substrate 106, but the actuator 121 may be regarded as a device provided between the second flow path substrate 106 and the third flow path substrate 107. The diaphragm 109 may also be considered as one of the components of the piezoelectric element 108.

[0023] (Actuator) Next, the detailed configuration of the actuator 121 will be described. Figures 2(a) and (b) are schematic diagrams showing the configuration of the actuator 121. Figure 2(a) is a top view of the second flow path substrate 106 having a piezoelectric element 108 formed on its upper surface, as viewed from the Z direction. Figure 2(b) is a BB cross-sectional view of Figure 2(a), showing the state of the actuator 121 as viewed from the Y direction. Note that in Figure 2(a), in order to show the arrangement of the films and electrodes constituting the piezoelectric element 108, the sealing film 211 covering the piezoelectric element 108 and some of the films of the piezoelectric element 108 are omitted from illustration.

[0024] The periphery of the vibration plate 109 constituting the outer wall of the pressure chamber 102 is surrounded by a restraining region including a first restraining region 118 and a second restraining region 119. On the opposite side of the vibration plate 109 to the pressure chamber 102, a piezoelectric element 108 having a membrane structure that can change the volume of the pressure chamber 102 by expanding and contracting it is provided. The piezoelectric element 108 is composed of a piezoelectric film 110, an upper electrode 111, and a lower electrode 112 formed on the vibration plate 109. The actuator 121 includes an upper electrode pad 114 and a lower electrode pad 115 in addition to the piezoelectric element 108 and the vibration plate 109, and the piezoelectric element 108 is covered with an insulating film 210 and a sealing film 211.

[0025] 2(b), the piezoelectric element 108 is composed of a piezoelectric film 110, and an upper electrode 111 and a lower electrode 112 formed so as to sandwich the piezoelectric film 110 from above and below. When a voltage is applied to the upper electrode 111 and the lower electrode 112 of the piezoelectric element 108, the piezoelectric element 108 is driven and a droplet 113 is ejected from the ejection port 101. A voltage of several tens of volts is required to obtain a sufficient amount of displacement of the piezoelectric element 108 for ejecting droplets. In order to protect the electrodes of the piezoelectric element 108 and the wiring connected to the electrodes, the various electrodes and wiring are covered with an insulating film 210 and a sealing film 211 having insulating properties.

[0026] The membrane-structured piezoelectric element 108 constitutes an actuator 121, which is a unimorph type piezoelectric actuator. A piezoelectric film 110 constituting the piezoelectric element 108 is formed on the installation surface 109a side of the vibration plate 109. The piezoelectric element 108 is formed on the opposite side of the vibration plate 109 to the pressure chamber 102, and is sealed by the vibration plate 109 and the third flow path substrate 107, etc. With this arrangement, the piezoelectric element 108 is arranged so as not to come into contact with the ink. In the first embodiment, the longitudinal direction of the piezoelectric element 108 and the vibration plate 109 is parallel to the X direction, and the lateral direction intersecting the longitudinal direction is parallel to the Y direction.

[0027] The lower electrode 112 is a first electrode layer in contact with the installation surface 109a, and the piezoelectric film 110 is laminated on the lower electrode 112 as a piezoelectric layer. The X-direction length of the lower electrode 112 is longer than the X-direction length of the piezoelectric film 110. In the X-direction (first direction), one end of the lower electrode 112 is located at approximately the same position as a first end 110a which is one end of the piezoelectric film 110, and the other end of the lower electrode 112 is located beyond a second end 110b which is the other end of the piezoelectric film 110. In other words, the other end of the lower electrode 112 extends in the X-direction relative to the second end 110b of the piezoelectric film 110.

[0028] The upper electrode 111 is a second electrode layer laminated on the piezoelectric film 110. The X-direction length of the upper electrode 111 is approximately equal to the X-direction length of the piezoelectric film 110. That is, in the X-direction, one end of the upper electrode 111 is located at approximately the same position as the first end 110a of the piezoelectric film 110, and the other end of the upper electrode 111 is located at approximately the same position as the second end 110b of the piezoelectric film 110. In this manner, the piezoelectric element 108 is configured by stacking the lower electrode 112, the piezoelectric film 110, and the upper electrode 111 in this order in the Z direction (second direction) perpendicular to the installation surface 109a. The widths of the lower electrode 112, the piezoelectric film 110, and the upper electrode 111 in the Y direction (third direction) are approximately equal to each other.

[0029] An upper electrode pad 114 is provided as a first electrode member at the end of the piezoelectric element 108 on the first end 110a side. is disposed on the upper electrode 111, and a lower electrode pad 115 is disposed on the end on the second end 110b side as a second electrode member. The upper electrode pad 114 is connected to the end on the first end 110a side of the upper electrode 111. The lower electrode pad 115 is the end on the second end 110b side of the lower electrode 112, and is connected to an extension region extending in the X direction from the piezoelectric film 110. In the first embodiment, electrode members such as the upper electrode pad 114 and the lower electrode pad 115 are described as being distinguished from the piezoelectric element 108, but these electrode members may be regarded as components of the piezoelectric element 108.

[0030] A signal wiring 200 for supplying an operating signal and a common wiring 201 for applying a common potential are connected to the piezoelectric elements 108. The signal wiring 200 is connected to the upper electrode pad 114 and extends from the upper electrode pad 114 in the X direction. That is, the upper electrode pad 114 electrically connects the upper electrode 111 and the signal wiring 200. The common wiring 201 is electrically connected to the lower electrode pad 115 and extends from the lower electrode pad 115 in the X direction. The common wiring 201 applies a common potential to the plurality of piezoelectric elements 108. That is, the lower electrode pad 115 electrically connects the lower electrode 112 and the common wiring 201.

[0031] The diaphragm 109 can be selected from silicon nitride film, silicon, metal, heat-resistant glass, etc., as long as it satisfies necessary mechanical properties, reliability, etc. In the first embodiment, as an example of the configuration of the diaphragm 109, an SOI (Silicon On Insulator) wafer is used for the diaphragm 109. The diaphragm 109 is formed of a silicon oxide film (BOX layer) 207, a silicon film (device layer) 208, and a silicon oxide film 209. These films are laminated in the order of silicon oxide film 207, silicon film 208, and silicon oxide film 209 from the side farthest from the piezoelectric element 108.

[0032] Lead zirconate titanate, which is easy to obtain a large amount of displacement, is mainly used for the piezoelectric film 110, but other piezoelectric materials such as barium titanate, lead titanate, lead metaniobate, bismuth titanate, zinc oxide, aluminum nitride, potassium sodium niobate, etc. Also, the piezoelectric film 110 may be composed of multiple layers.

[0033] The lower electrode 112 may be exposed to high temperatures of several hundred degrees Celsius in the subsequent process, so it is preferable to use a material with a high melting temperature. Examples of such materials include copper, platinum, gold, chromium, cobalt, titanium, and alloys thereof. In addition, when the piezoelectric film 110 is formed in contact with the upper surface of the lower electrode 112, the lower electrode 112 may be configured as a film that controls the crystal orientation of the piezoelectric film 110. In this case, a material having an appropriate crystal structure is appropriately selected. For example, when the material of the piezoelectric film 110 is lead zirconate titanate, it is preferable to use platinum as the crystal orientation control film.

[0034] The upper electrode 111 may be any material that is conductive, and may be made of materials generally used as electrodes, such as aluminum, copper, tungsten, titanium, chromium, gold, platinum, etc. However, if the internal stress of the lower electrode 112 or the like is large and the piezoelectric film 110 is bent, the upper electrode 111 may be given an opposite internal stress to offset the stress of the entire element. An example of such a material is an alloy of titanium and tungsten.

[0035] The signal wiring 200 and the common wiring 201 can be made of materials used for general electric wiring. Examples of materials that can be used include aluminum, copper, gold, and alloys of these. A titanium or chromium film may be inserted to improve adhesion to the underlayer. The piezoelectric element 108 is generally driven by applying a high voltage of 30 V or more at a high frequency of several hundred to several thousand Hz. Therefore, the wiring needs to have a high slew rate, and measures such as making the wiring film relatively thick are required.

[0036] The insulating film 210 is formed on the upper electrode 111 and the extending region of the lower electrode 112. The insulating film 210 has openings for the upper contact portion 210a and the lower contact portion 204. The insulating film 210 may be regarded as a component of the piezoelectric element .

[0037] The upper contact portion 210a opens in the vicinity of the first end 110a of the piezoelectric element 108, and an upper electrode pad 114 communicating with the signal wiring 200 is formed on the upper layer thereof. The upper electrode pad 114 and the upper electrode 111 are electrically connected via the upper contact portion 210a.

[0038] The lower contact portion 210b is located near the second end 110b of the piezoelectric element 108 and opens above the extending region of the lower electrode 112. A lower electrode pad 115 communicating with the common wiring 201 is formed on the upper layer of the lower contact portion 210b. The lower electrode pad 115 and the lower electrode 112 are electrically connected via the lower contact portion 210b.

[0039] The sealing film 211 is formed on the upper electrode pads 114, the signal wiring 200, the lower electrode pads 115, and the common wiring 201. These electrical connection members are electrically protected by being covered with the sealing film 211. The sealing film 211 is also formed on the insulating film 210 on which the upper electrode pads 114 and the lower electrode pads 115 are not provided. The sealing film 211 may be regarded as a component of the piezoelectric element 108.

[0040] For the insulating film 210, general insulating materials such as silica, silicon nitride, oxynitride, alumina, etc. can be used. However, as described above, a high voltage of 30 V or more is generally applied to drive the piezoelectric element 108, so the material and film thickness must be selected taking into consideration the breakdown electric field strength.

[0041] The upper electrode pad 114 may be integrally formed with the same material as the signal wiring 200. Similarly, the lower electrode pad 115 may be integrally formed with the same material as the common wiring 201. That is, an electrode member in which an electrode pad and a wiring are integrally formed may be configured to be connected to each electrode of the piezoelectric element 108. Here, as described above, the film thickness of the signal wiring 200 and the common wiring 201 is generally set to be thick. Furthermore, for example, when an aluminum alloy is used as the material of the wiring member, its Young's modulus is approximately 60 to 100 GPa, which is equivalent to that of a general piezoelectric film. That is, when the wiring and the electrode pad are integrally formed, in the configuration of the first embodiment, a relatively thick and highly rigid metal film is covered near the first end 110a of the piezoelectric element 108. As a result, the displacement near the first end 110a of the piezoelectric element 108 is suppressed by the upper electrode pad 114.

[0042] In the first embodiment, the signal wiring 200 is disposed at a position that does not overlap the piezoelectric element 108 when viewed in the Z direction, but the signal wiring 200 may be disposed so as to overlap an end portion of the piezoelectric element 108 on the side of the first end 110a. In such a configuration, the signal wiring 200 functions as a part of an electrode member that suppresses displacement in the vicinity of the first end 110a of the piezoelectric element 108. Furthermore, when the signal wiring 200 is directly connected to the upper electrode 111 without passing through the upper electrode pad 114, the signal wiring 200 functions as an electrode member and wiring member, and suppresses displacement in the vicinity of the first end 110a of the piezoelectric element 108.

[0043] The sealing film 211 is required to have a function of preventing failures caused by current flowing through the device surface in a high humidity environment. For this reason, the sealing film 211 has high insulating properties and high coverage, and covers the signal wiring 200, the common wiring 201, the upper electrode pad 114, and the lower electrode pad 115. As a material used for the sealing film 211, silica, silicon nitride, alumina, etc., which have high insulating properties, are preferably used.

[0044] Generally, a material with high rigidity is suitable for use in the sealing film 211. For example, silicon The Young's moduli of alumina and silicon nitride are approximately 120 to 300 GPa and 170 to 360 GPa, respectively, which are much higher than the 60 to 100 GPa of lead zirconate titanate. Therefore, if the entire surface of the piezoelectric element 108 is covered with the sealing film 211, the displacement of the piezoelectric element 108 is significantly reduced, and there is a risk that the ink ejection operation will not be performed normally. Therefore, in the first embodiment, the sealing film 211 is removed from the region of the piezoelectric element 108 that does not need to be covered with the sealing film 211. In other words, in order to prevent the displacement of the piezoelectric element 108 from being excessively suppressed, a recess 211a is formed in the sealing film 211 on the piezoelectric element 108 as a film-removed region where at least a part of the film is removed.

[0045] The recess 211a is formed at a position between the first end 110a and the second end 110b in the X direction and at a position overlapping with the piezoelectric film 110, the upper electrode 111, and the lower electrode 112 when viewed in the Z direction. The Y-direction width of the recess 211a is smaller than the Y-direction width of the piezoelectric element 108. The recess 211a in the first embodiment is substantially rectangular when viewed in the Z direction, and its outline is shown by a dotted line in FIG. 2(a). Note that the recess 211a may be a region where the film has been completely removed, or may be a region where a portion of the film has been removed and a film with a relatively thin thickness remains compared to other regions.

[0046] In Fig. 2(b), the X-direction distance from the first end 110a of the piezoelectric film 110 to the end 211b of the recess 211a on the first end 110a side is shown as distance d1. In addition, in Fig. 2(b), the X-direction distance from the second end 110b of the piezoelectric film 110 to the end 211c of the recess 211a on the second end 110b side is shown as distance d2. In the first embodiment, the recess 211a of the sealing film 211 is formed so that the distance d2 is greater than the distance d1 in the longitudinal direction (X direction, first direction) of the piezoelectric element 108. To explain the reason for configuring the sealing film 211 in this way, the displacement suppression effect of the sealing film 211 will first be explained.

[0047] (Comparative Example) Prior to the description of the displacement suppression effect by the configuration of the first embodiment, a comparative example will be described in which a sealing film 211 configured so that the distance d1 and the distance d2 are equal is formed. The configuration of the comparative example is different from that of the first embodiment in the end position of the second end 110b side of the recess 211a of the sealing film 211. FIGS. 3(a) and (b) are schematic diagrams showing the configuration of an actuator 121 according to the comparative example. FIG. 3(a) is a top view of a second flow path substrate 106 having a piezoelectric element 108 formed on its upper surface, as viewed from the Z direction. FIG. 3(b) is a CC cross-sectional view of FIG. 3(a), showing the state of the actuator 121 as viewed from the Y direction. Note that in FIG. 3(a), the sealing film 211 covering the piezoelectric element 108 and a part of the film of the piezoelectric element 108 are omitted from illustration in order to show the arrangement of the film and electrodes constituting the piezoelectric element 108.

[0048] As described above, the distance d2 in the comparative example is equal to the distance d1 and is smaller than the distance d2 in the first embodiment. Therefore, in the comparative example, the effect of the sealing film 211 in suppressing the displacement of the piezoelectric element 108 is the same at both ends in the X direction.

[0049] An upper electrode pad 114 is disposed so as to overlap an end portion of the piezoelectric film 110 on the first end 110a side. Meanwhile, the lower electrode pad 115 is connected to an extending region of the lower electrode 112 where the piezoelectric film 110 does not overlap, and no electrode member (electrode film) overlaps an end portion of the piezoelectric film 110 on the second end 110b side. As described above, the electrode members such as the upper electrode pad 114 can suppress the displacement of the piezoelectric element 108 in the same manner as the sealing film 211. Therefore, in the comparative example, the effect of the electrode members in suppressing the displacement of the piezoelectric element 108 is greater at the end portion on the first end 110a side than at the end portion on the second end 110b side.

[0050] 4 is a diagram showing a state in which the actuator 121 according to the comparative example is operated and the piezoelectric element 108 and the vibration plate 109 are displaced. As described above, the vicinity of the first end 110a of the piezoelectric element 108 is The electrode pad 114 suppresses the displacement. On the other hand, there is no electrode member such as an electrode pad on the upper layer of the second end 110b of the piezoelectric element 108, and the displacement is not suppressed. As a result, as shown in FIG. 4, the amount of displacement on the second end 110b side of the piezoelectric element 108 becomes larger than the amount of displacement on the first end 110a side, and the maximum displacement point of the piezoelectric element 108 moves closer to the second end 110b side, and the amount of displacement on the second end 110b side may become excessive. If the amount of displacement on the second end 110b side becomes excessive and the piezoelectric element 108 deforms more rapidly on the second end 110b side, stress is concentrated at the boundary between the piezoelectric film 110 and the lower electrode 112 at the second end 110b of the piezoelectric element 108, and the piezoelectric film 110 and the lower electrode 112 may be damaged or the interface may peel off.

[0051] Therefore, in the first embodiment, in order to reduce the difference between the amount of displacement (degree of displacement) on the first end 110a side and the amount of displacement (degree of displacement) on the second end 110b side, the recess 211a is configured so that the deformation on the second end 110b side of the piezoelectric element 108 can be largely suppressed by the sealing film 211. More specifically, the distance d2 is made larger than the distance d1. With this configuration, the end of the piezoelectric film 110 on the second end 110b side is covered more by the thicker part of the sealing film 211 (the part excluding the recess 211a) than the end on the first end 110a side.

[0052] 5 is a diagram showing a state in which the actuator 121 according to the first embodiment operates and the piezoelectric element 108 and the vibration plate 109 are displaced. In the first embodiment, the sealing film 211 has a higher effect of suppressing the displacement on the second end 110b side than in the comparative example. As shown in FIG. 5, the difference between the amount of displacement on the first end 110a side and the amount of displacement on the second end 110b side is reduced, and the maximum displacement point of the piezoelectric element 108 is located approximately halfway between the first end 110a and the second end 110b in the X direction. As a result, the stress concentration on the second end 110b of the piezoelectric element 108 is alleviated, and damage to the piezoelectric element 108 is suppressed.

[0053] As described above, in the configuration of the first embodiment, in order to suppress deviation in the X direction of deformation of the piezoelectric element 108 when the actuator 121 is operated, the recess 211a is formed in the sealing film 211 so that the distance d2 is greater than the distance d1. With such a configuration, damage to the piezoelectric film 110 or the lower electrode 112 and the occurrence of interfacial peeling between the piezoelectric film 110 and the lower electrode 112 are suppressed, and damage to the piezoelectric element 108 is suppressed.

[0054] (Method of Manufacturing Element Substrate) Next, an example of a method for manufacturing the element substrate 10 according to the first embodiment will be described. First, a method for manufacturing the second flow path substrate 106 including the actuators 121 will be described with reference to Figs. 6(a) to (i), and a method for manufacturing the element substrate 10 using the second flow path substrate 106 will be described with reference to Figs. 7(a) to (c). Figs. 6(a) to (i) are diagrams showing a method for manufacturing the actuators 121 of the second flow path substrate 106. Figs. 7(a) to (c) are diagrams showing a method for manufacturing the element substrate 10.

[0055] 6(a) shows a state in which a silicon oxide film 207, a silicon film 208, and a silicon oxide film 209 constituting the diaphragm 109 are formed on a base layer 122 of a second flow path substrate 106. The base layer 122 is an SOI wafer. A silicon thermal oxide film of about 500 nm is formed by a wet oxidation method using oxygen and hydrogen gas, and a silicon oxide film 209 serving as an insulating film is formed.

[0056] 6(b) shows a state in which the lower electrode 112, the piezoelectric film 110, and the upper electrode 111 are formed on the diaphragm 109. The lower electrode 112, the piezoelectric film 110, and the upper electrode 111 are formed in this order so as to be stacked on top of each other on the diaphragm 109.

[0057] First, a platinum film having a thickness of 90 to 110 nm was formed by sputtering as the lower electrode 112. In order to obtain a strong adhesive force between the lower electrode 112 and the silicon oxide film 209, Then, a titanium layer with a thickness of 5 to 15 nm was formed as an adhesive layer (not shown). Next, a sol-gel method was used to form a piezoelectric film 110 with a thickness of 1.9 to 2.1 μm on the lower electrode 112 so as to be oriented in the (100) direction. The Young's modulus of the piezoelectric film 110 was 70 to 100 GPa. Then, the upper electrode 111 was formed by a sputtering method. An alloy of titanium and tungsten was used as the material for the upper electrode 111, and the thickness was 90 to 110 nm.

[0058] 6(c) shows a state in which the piezoelectric film 110 and the upper electrode 111 are etched. The upper electrode 111 and the piezoelectric film 110 are etched after a resist pattern (not shown) is formed by photolithography so as to have a desired pattern.

[0059] FIG. 6(d) shows the state where the lower electrode 112 has been etched. A resist pattern is formed again by photolithography so as to have a desired pattern on the lower electrode 112, and then the lower electrode 112 is etched. At this time, in the longitudinal direction of the piezoelectric element 108, one end of the lower electrode 112 is at approximately the same position as one end of the piezoelectric film 110, and the other end of the lower electrode 112 protrudes from the other end of the piezoelectric film 110. In other words, the lower electrode 112 is etched so that its longitudinal length is longer than that of the piezoelectric film 110. Through these procedures, the piezoelectric element 108 consisting of the lower electrode 112, the piezoelectric film 110, and the upper electrode 111 is formed.

[0060] 6(e) shows a state where the insulating film 210 has been formed. The insulating film 210 according to the first embodiment is a silicon oxide film having a thickness of 350 to 450 nm, and is formed by a CVD method. The insulating film 210 is formed so as to cover the entire surface of the piezoelectric element 108.

[0061] 6(f) shows a state in which the upper contact portion 210a and the lower contact portion 210b are formed in the insulating film 210. The upper contact portion 210a is an opening (through hole) for connecting the upper electrode pad 114 to the upper electrode 111, and is formed by etching the insulating film 210 after a resist pattern (not shown) is formed by photolithography. Similarly, the lower contact portion 210b is an opening (through hole) for connecting the lower electrode pad 115 to the lower electrode 112, and is formed by etching.

[0062] The upper contact portion 210a, which is a first opening, is formed at a position overlapping with the piezoelectric film 110 when viewed in the stacking direction of the piezoelectric element 108. On the other hand, the lower contact portion 210b, which is a second opening, is formed at a position not overlapping with the piezoelectric film 110 when viewed in the stacking direction of the piezoelectric element 108, but at a position overlapping with a portion of the lower electrode 112 protruding from the piezoelectric film 110.

[0063] FIG. 6(g) shows the state where wiring composed of the signal wiring 200, the common wiring 201, the upper electrode pad 114, the lower electrode pad 115, etc. is formed. In forming these wiring members (electrode members), first, a film is formed on the insulating film 210 by a sputtering method. In the first embodiment, an alloy material of aluminum and copper is used as the material of each wiring member, and each thickness is set to 500 to 700 nm. The Young's modulus of each wiring member is 60 to 80 GPa. After the film formation, a resist pattern (not shown) is formed by a photolithography method so as to have a desired pattern, and then the signal wiring 200, the common wiring 201, the upper electrode pad 114, and the lower electrode pad 115 are formed by etching.

[0064] Through the above-mentioned steps, in this manufacturing example, the signal wiring 200 and the upper electrode pad 114 are integrally formed of the same material, and the upper electrode pad 114 is connected to the upper electrode 111 via the upper contact portion 210a. Similarly, the common wiring 201 and the lower electrode pad 115 are integrally formed of the same material, and the lower electrode pad 115 is connected to the lower electrode 112 via the lower contact portion 210b. Then, each electrode member and each wiring member are formed so that the signal wiring 200 and the upper electrode pad 114 have the same thickness in the Z direction, and the common wiring 201 and the lower electrode pad 115 have the same thickness in the Z direction.

[0065] 6(h) shows a state where the sealing film 211 has been formed. The sealing film 211 is formed so as to cover the piezoelectric elements 108, the signal wiring 200, the common wiring 201, the upper electrode pads 114, and the lower electrode pads 115. The sealing film 211 is a highly moisture-proof silicon nitride film formed by a CVD method to a film thickness of 150 to 250 nm. The Young's modulus of the sealing film 211 is 120 to 150 GPa, which is larger than the Young's modulus of the various wiring members and the piezoelectric film 110.

[0066] 6(i) shows a state in which a recess 211a is formed in the sealing film 211. The recess 211a is formed by forming a resist pattern (not shown) by photolithography, and then etching the sealing film 211. In the first embodiment, the recess 211a is formed in a rectangular shape at a position overlapping with the piezoelectric film 110 when viewed in the stacking direction of the piezoelectric element 108.

[0067] The recess 211a is formed so that the distance d2 from the second end 110b of the piezoelectric film 110 to the end 211b on the second end 110b side of the recess 211a is larger than the distance d1 from the first end 110a of the piezoelectric film 110 to the end 211b on the first end 110a side of the recess 211a. More specifically, the recess 211a is formed so that the distance d2 is 1.5 times or more and 2.0 times or less than the distance d1. In the first embodiment, the sealing film 211 is completely removed in the recess 211a, but whether or not a film is left in the recess 211a, and the film thickness of the recess 211a when the film is left, can be appropriately determined in consideration of the displacement amount of the piezoelectric element 108, etc. In addition, although not shown in the drawing, the sealing film 211 on the voltage application electrode terminal for driving the actuator present at the wiring ends of the signal wiring 200 and the common wiring 201 is also opened by the etching for forming the recess 211a.

[0068] 7(a) shows a state in which the first flow path substrate 105 and the second flow path substrate 106 are bonded together. After the recess 211a is formed in the sealing film 211, the second flow path substrate 106 is bonded to the first flow path substrate 105 via the adhesive layer 212. In the first embodiment, the bonded portion in the vicinity of the first end 110a of the piezoelectric element 108 becomes the first constraint region 118 and functions as a constraint region.

[0069] The first flow path substrate 105 is fabricated by processing a Si substrate. Before bonding, the first flow path substrate 105 has a cavity portion 205 at a position facing the piezoelectric element 108 and a supply flow path 103 that will later communicate with the pressure chamber 102. When the first flow path substrate 105 and the second flow path substrate 106 are bonded together, the piezoelectric element 108 is accommodated inside the cavity portion 205 and is located between the first flow path substrate 105 and the vibration plate 109.

[0070] FIG. 7(b) shows a state where the pressure chamber 102 is formed in the second flow path substrate 106. In this manufacturing example, the second flow path substrate 106 is ground from the rear side of the surface on which the piezoelectric element 108 is formed until the thickness becomes 60 to 80 μm, and then the pressure chamber 102 is formed. The pressure chamber 102 is a space on the opposite side of the vibration plate 109 to the piezoelectric element 108 (cavity portion 205), and is communicated with the supply flow path 103. Then, by forming the pressure chamber 102, the vibration plate 109 is configured to be vibrable, and the actuator 121 is completed. In the first embodiment, the non-machined portion in the vicinity of the second end 110b of the piezoelectric element 108 becomes the second constraint region 119 and functions as the constraint region.

[0071] In the first embodiment, in the longitudinal direction of the piezoelectric element 108, a distance L1 from an end of the first constraint region 118 to a first end 110a of the piezoelectric element 108 and a distance L2 from an end of the second constraint region 119 to a second end 110b of the piezoelectric element 108 are set to be substantially equal. In other words, the piezoelectric element 108 is placed on the longitudinal center of the unconstrained region of the vibration plate 109.

[0072] FIG. 7C shows a state where the second flow path substrate 106 and the third flow path substrate 107 are bonded together. The second flow path substrate 106 in which the pressure chambers 102 are formed is bonded to the third flow path substrate 107 by an adhesive layer 2. The third flow path substrate 107 is bonded via a piezoelectric element 108. The third flow path substrate 107 is fabricated by processing a Si substrate, and the ejection port 101 is formed on the surface opposite to the bonding surface of the second flow path substrate 106. The ejection port 101 is provided at a position overlapping with the piezoelectric element 108 when viewed in the ink ejection direction when the second flow path substrate 106 and the third flow path substrate 107 are bonded.

[0073] The element substrate 10 produced through the above-mentioned steps is mounted and assembled on electrical components and support members, etc., to complete a liquid ejection head unit. A high-temperature, high-pressure bias test was conducted on this liquid ejection head unit in order to evaluate its durability. Specifically, a DC voltage of 60 V was applied to the actuator 121 in an environment of 85°C temperature and 85% humidity for 200 hours while driving the actuator 121. After that, when the state of the piezoelectric element 108 was checked, no damage or peeling of the piezoelectric element 108 was observed, and it was confirmed that the piezoelectric element 108 was maintained in a normal state.

[0074] As described above, according to the configuration of the first embodiment, the sealing film 211 for preventing dielectric breakdown suppresses damage to the piezoelectric element 108 at the end on the side where the upper electrode pad 114 is not arranged. Specifically, the region on the piezoelectric element 108 where the sealing film 211 is formed is provided broader in the end region of the piezoelectric element 108 where the upper electrode pad 114 is not arranged than in the end region of the piezoelectric element 108 where the upper electrode pad 114 is arranged, thereby suppressing damage to the piezoelectric element 108.

[0075] <Second embodiment> Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the shape of the recess 211a formed in the sealing film 211. Only the differences between the configuration of the second embodiment and the configuration of the first embodiment will be described below. The same reference numerals will be used to designate the same parts of the configuration of the second embodiment as those of the first embodiment, and the description will be omitted.

[0076] 8(a) and (b) are schematic diagrams showing the configuration of an actuator 121 according to the second embodiment. FIG. 8(a) is a top view of a second flow path substrate 106 having a piezoelectric element 108 formed on its upper surface, as viewed from the Z direction. FIG. 8(b) is a DD cross-sectional view of FIG. 8(a), showing the state of the actuator 121 as viewed from the Y direction. Note that in FIG. 8(a), the sealing film 211 covering the piezoelectric element 108 and some of the films of the piezoelectric element 108 are omitted from illustration in order to show the arrangement of the films and electrodes that constitute the piezoelectric element 108.

[0077] The recess 211a of the second embodiment is formed in a convex shape such that the center in the Y direction of the end 211c on the second end 110b side is convex toward the second end 110b when viewed in the Z direction. That is, the Y direction width of the end of the recess 211a on the second end 110b side gradually decreases toward the second end 110b. With this configuration, the amount of displacement of the piezoelectric element 108 is made uniform on the first end 110a side and the second end 110b side, and the effect of suppressing damage to the piezoelectric element 108 is enhanced.

[0078] Since both ends of the vibration plate 109 in the Y direction are also constrained, the central portion of the piezoelectric element 108 in the Y direction is displaced the most when the actuator 121 is driven. Therefore, in order to adjust the amount of displacement of the piezoelectric element 108 evenly on the first end 110a side and the second end 110b side, the amount of sealing film 211 at the position corresponding to the central portion of the piezoelectric element 108 in the Y direction is particularly important. Therefore, in the second embodiment, the X-direction length of the recess 211a is made large at the central portion in the Y direction to prevent the displacement of the piezoelectric element 108 from being excessively suppressed and to ensure the amount of displacement of the piezoelectric element 108.

[0079] On the other hand, the presence or absence of sealing film 211 and the thickness of the film in the region corresponding to the Y-direction end of piezoelectric element 108 do not have a large effect on the amount of displacement of piezoelectric element 108, compared to the region corresponding to the Y-direction center. Also, peeling of piezoelectric film 110 from lower electrode 112 in the vicinity of second end 110b can occur not only in the Y-direction center or end of piezoelectric element 108. Therefore, in the second embodiment, In this embodiment, the area of ​​the recess 211a on the second end 110b side is reduced compared to the first embodiment, thereby improving the strength of the piezoelectric element 108 at the Y-direction end portion and enhancing the effect of suppressing damage to the piezoelectric element 108. Specifically, the end portion of the recess 211a on the second end 110b side is formed in a convex shape toward the second end 110b, thereby increasing the area where the sealing film 211 with a large thickness exists at both ends in the Y direction.

[0080] Moreover, in the second embodiment, the Y-direction width of the recess 211a is larger than the Y-direction width of the piezoelectric element 108. Compared to the end portion on the second end 110b side of the piezoelectric element 108, the piezoelectric film 110 and the lower electrode 112 are less likely to be damaged or peeled off in other regions. Therefore, in the second embodiment, the sealing film 211 is removed as much as possible from positions corresponding to regions where the piezoelectric element 108 is less likely to be damaged, thereby suppressing a decrease in the displacement amount of the piezoelectric element 108 due to the sealing film 211 and ensuring the displacement amount of the piezoelectric element 108 necessary for droplet ejection.

[0081] In the second embodiment, the distance d2 from the second end 110b of the piezoelectric element 108 to the end 211c of the recess 211a is set to be 2.0 times or more and 2.5 times or less than the distance d1 in the X direction from the first end 110a of the piezoelectric element 108 to the end 211b of the recess 211a. In this way, the size of the distance d2 relative to the distance d1 can be appropriately changed depending on the shape of the recess 211a and other factors, and it is particularly preferable that the distance d2 is set within a range of 1.5 times or more and 2.5 times or less than the distance d1. The distances d1 and d2 are defined as the shortest distances from the end of the piezoelectric film 110 to the end of the recess 211a. Specifically, the distance d2 from the second end 110b of the piezoelectric element 108 to the end 211c of the recess 211a is the distance from the second end 110b of the piezoelectric element 108 to the tip of the convex portion of the recess 211a.

[0082] In the second embodiment, the joint between the second flow path substrate 106 and the first flow path substrate 105 constitutes the first constrained region 118 and the second constrained region 119. In the second embodiment, wiring members and electrode members such as wiring and electrode pads are not arranged at the joint. The reason is that the wiring members have a film thickness of 500 to 700 nm, and if the wiring members have unevenness at the joint, the joint reliability may deteriorate. That is, when viewed in the Z direction, the signal wiring 200 and the common wiring 201 are arranged at positions that do not overlap with the first constrained region 118 and the second constrained region 119, so that the deterioration of the joint reliability can be suppressed. In the second embodiment, the signal wiring 200 connected to the upper electrode pad 114 extends from the upper electrode pad 114 in the Y direction, and the common wiring 201 connected to the lower electrode pad 115 extends from the lower electrode pad 115 in the Y direction.

[0083] However, when the wiring member is not disposed at the joint, the amount of displacement near the second end 110b of the piezoelectric element 108 can be much larger than the amount of displacement near the first end 110a. This is because the second constraint region 119 must be disposed at least as far away as the lower electrode pad 115 from the piezoelectric element 108. Then, in the X direction, the distance L2 from the end of the second constraint region 119 closer to the second end 110b to the second end 110b of the piezoelectric element 108 is longer than the distance L1 from the end of the first constraint region 118 closer to the first end 110a to the first end 110a of the piezoelectric element 108. In FIG. 8(a), the distance L1 and the distance L2 are respectively shown.

[0084] The area of ​​the piezoelectric element 108 indicated by distance L1 and distance L2 is an area where the piezoelectric film 110 is not formed, and is the area with the lowest rigidity and the easiest to displace among the unconstrained areas. Since the area near the second end 110b of the piezoelectric element 108 that is most susceptible to displacement corresponding to distance L2 is occupied by the area, the amount of displacement on the second end 110b side of the piezoelectric element 108 is much larger than the amount of displacement on the first end 110a side. As a result, a large stress concentration occurs at the end of the piezoelectric element 108 on the second end 110b side, further increasing the risk of damage and peeling of the piezoelectric element 108. Even with this configuration, according to the second embodiment, Since the sealing film 211 is provided over a large area, the effect of suppressing damage to the piezoelectric element 108 is effectively obtained, and the risk of damage to the piezoelectric element 108 is reduced. That is, in a configuration in which the distance L2 is equal to or greater than the distance L1, setting the distance d1 to equal to or greater than the distance d2 and forming the recess 211a in the shape shown in Fig. 8(a) is particularly effective in reducing the risk of damage to the piezoelectric element 108. In addition, such a configuration is also effective in the case where the restraint region of the vibration plate 109 is formed by something other than bonding with the first flow path substrate 105 or the second flow path substrate 106.

[0085] In order to confirm the effect of the configuration of the second embodiment, a high-temperature, high-pressure bias test was performed on a liquid ejection head unit including the element substrate 10 according to the second embodiment to evaluate its durability. Specifically, a DC voltage of 60 V was applied to drive the actuator 121 for 200 hours in an environment of 85° C. and 85% humidity. After that, the state of the piezoelectric element 108 was checked, and it was confirmed that the piezoelectric element 108 was not broken or peeled off and maintained a normal state, despite the increased risk of breakage and peeling. As described above, according to the configuration of the second embodiment, the effect of suppressing damage to the piezoelectric element 108 can be further improved compared to the configuration of the first embodiment.

[0086] In the above embodiment, one recess 211a is formed corresponding to each piezoelectric element 108, but the recess 211a may be divided into a plurality of regions. The shape of the recess 211a is not limited to a rectangle, and may be, for example, an ellipse or an oval. In other words, the configuration of the recess 211a, such as the shape and film thickness, may be appropriately changed according to the configuration of other members.

[0087] The disclosure of this embodiment includes the following configuration. (Configuration 1) A vibrating plate provided so as to be vibrated; a piezoelectric element including a first electrode layer in contact with a first surface of the vibration plate, a second electrode layer, and a piezoelectric layer having a first end in a first direction parallel to the first surface and a second end opposite to the first end, the piezoelectric element being placed on the first surface with the first electrode layer, the piezoelectric layer, and the second electrode layer stacked in this order in a second direction perpendicular to the first surface; an electrode member connected to the second electrode layer at a position overlapping an end portion of the piezoelectric layer on the first end side when viewed in the second direction; a sealing film covering at least a portion of the piezoelectric element, the sealing film having a recess formed between the first end and the second end and recessed in the second direction; Equipped with An actuator in which the distance in the first direction from the second end of the piezoelectric layer to the end of the recess on the second end side is longer than the distance from the first end of the piezoelectric layer to the end of the recess on the first end side. (Configuration 2) 2. The actuator according to claim 1, wherein the first direction is parallel to a longitudinal direction of the piezoelectric element. (Configuration 3) 3. The actuator according to claim 1 or 2, further comprising a wiring member connected to the electrode member and positioned so as to overlap an end portion of the piezoelectric layer on the first end side when viewed in the second direction. (Configuration 4) 4. The actuator according to configuration 3, wherein the electrode members and the wiring members are made of the same material and have the same thickness in the second direction. (Configuration 5) An actuator described in any one of configurations 1 to 4, wherein the distance from the second end of the piezoelectric layer to the end of the recess on the second end side is 1.5 to 2.5 times the distance from the first end of the piezoelectric layer to the end of the recess on the first end side. (Configuration 6) The electrode member is a first electrode member, and a second electrode member is connected to the first electrode layer. the second electrode layer has an extension region that extends from the second end of the piezoelectric layer in the first direction, 6. The actuator according to any one of configurations 1 to 5, wherein the second electrode member is connected to the first electrode layer in the extending region. (Configuration 7) Both ends of the diaphragm in the first direction are constrained regions that are constrained so as to suppress vibration, 7. The actuator according to configuration 6, wherein a wiring member connected to the first electrode member or the second electrode member is disposed at a position that does not overlap with the restraint region when viewed in the second direction. (Configuration 8) an end portion of the diaphragm on the first end side in the first direction is a first constraint region that is constrained so as to suppress vibration, and an end portion of the diaphragm on the second end side in the first direction is a second constraint region that is constrained so as to suppress vibration, An actuator described in any one of configurations 1 to 7, wherein in the first direction, the distance from the end of the second constraint region closer to the second end to the second end of the piezoelectric layer is longer than the distance from the end of the first constraint region closer to the first end to the first end of the piezoelectric layer. (Configuration 9) The actuator according to any one of configurations 1 to 8, wherein the recess has a rectangular shape when viewed in the second direction. (Configuration 10) The actuator according to any one of configurations 1 to 8, wherein an end portion of the recess on the second end side in the first direction is formed in a convex shape with a central portion that is convex toward the second end side. (Configuration 11) 11. The actuator according to any one of configurations 1 to 10, wherein the recessed portion is a portion having a smaller thickness than other portions. (Configuration 12) 11. The actuator according to any one of configurations 1 to 10, wherein the recess is a portion where the sealing film has been completely removed. (Configuration 13) 13. The actuator according to any one of configurations 1 to 12, wherein the Young's modulus of the sealing film is greater than the Young's modulus of the electrode member. (Configuration 14) a first flow path substrate in which a discharge port for discharging a liquid is formed; a second flow path substrate having the actuator according to any one of claims 1 to 13, the actuator being arranged at a position overlapping with the ejection port when viewed in the second direction; An element substrate comprising: (Configuration 15) A device comprising the element substrate according to configuration 14, The liquid ejection head ejects liquid from the ejection port by applying a voltage to the first electrode layer and the second electrode layer to drive the actuator. [Explanation of symbols]

[0088] 108...piezoelectric element, 109...diaphragm, 109a...mounting surface (first surface), 110...piezoelectric film (piezoelectric layer), 110a...first end, 110b...second end, 111...upper electrode (second electrode layer), 114...upper electrode pad (electrode member), 121...actuator, 202...lower electrode (first electrode layer), 211...sealing film, 211a...recess

Claims

1. A vibrating plate provided so as to be vibrated; a piezoelectric element including a first electrode layer in contact with a first surface of the vibration plate, a second electrode layer, and a piezoelectric layer having a first end in a first direction parallel to the first surface and a second end opposite to the first end, the piezoelectric element being placed on the first surface by being stacked in a second direction perpendicular to the first surface in the order of the first electrode layer, the piezoelectric layer, and the second electrode layer; an electrode member connected to the second electrode layer at a position overlapping an end portion of the piezoelectric layer on the first end side when viewed in the second direction; a sealing film covering at least a portion of the piezoelectric element, the sealing film having a recess formed between the first end and the second end and recessed in the second direction; Equipped with An actuator in which the distance from the second end of the piezoelectric layer to the end of the recess on the second end side in the first direction is longer than the distance from the first end of the piezoelectric layer to the end of the recess on the first end side.

2. The actuator according to claim 1 , wherein the first direction is parallel to a longitudinal direction of the piezoelectric element.

3. The actuator according to claim 1 , further comprising a wiring member connected to the electrode member and disposed at a position overlapping an end portion of the piezoelectric layer on the first end side when viewed in the second direction.

4. The actuator according to claim 3 , wherein the electrode members and the wiring members are made of the same material and have the same thickness in the second direction.

5. 2. The actuator of claim 1, wherein a distance from the second end of the piezoelectric layer to an end of the recess on the second end side is greater than or equal to 1.5 times and less than or equal to 2.5 times a distance from the first end of the piezoelectric layer to an end of the recess on the first end side.

6. The electrode member is a first electrode member, and a second electrode member is connected to the first electrode layer. the second electrode layer has an extension region that extends from the second end of the piezoelectric layer in the first direction, The actuator according to claim 1 , wherein the second electrode member is connected to the first electrode layer in the extending region.

7. Both ends of the diaphragm in the first direction are constrained regions that are constrained so as to suppress vibration, The actuator according to claim 6 , wherein a wiring member connected to the first electrode member or the second electrode member is disposed at a position that does not overlap the restraint region when viewed in the second direction.

8. an end portion of the diaphragm on the first end side in the first direction is a first constraint region that is constrained so as to suppress vibration, and an end portion of the diaphragm on the second end side in the first direction is a second constraint region that is constrained so as to suppress vibration, 2. The actuator of claim 1, wherein in the first direction, a distance from an end of the second constraint region closer to the second end to the second end of the piezoelectric layer is longer than a distance from an end of the first constraint region closer to the first end to the first end of the piezoelectric layer.

9. The actuator according to claim 1 , wherein the recess has a rectangular shape when viewed in the second direction.

10. The actuator according to claim 1 , wherein an end portion of the recess on the second end side in the first direction is formed in a convex shape with a central portion that is convex toward the second end side.

11. The actuator according to claim 1 , wherein the recessed portion has a thickness smaller than that of other portions.

12. The actuator according to claim 1 , wherein the recess is a portion where the sealing film is completely removed.

13. The actuator according to claim 1 , wherein the Young's modulus of the sealing film is greater than the Young's modulus of the electrode member.

14. a first flow path substrate having a discharge port for discharging liquid formed therein; a second flow path substrate having the actuator according to any one of claims 1 to 13, the actuator being arranged at a position overlapping with the ejection port when viewed in the second direction; An element substrate comprising:

15. The element substrate according to claim 14, The liquid ejection head is configured such that, when a voltage is applied to the first electrode layer and the second electrode layer, the actuator is driven to eject liquid from the ejection port.

Images